Connor's 40K energy weapons discussion - re-re-revised ed.

[Connor MacLeod]

Yes, I'm having yet another change of mind. This represents the third iteration (not including some unfinished stuff I intended in some distant future to post prior to my current change of heart) and at this point, I need to stop thinking I've settled things. I always end up eating my own words (that "battleship recoil" calc still haunts me.) because my research is only as good as the information I can locate - and that means there's a good chance I can be either wrong, or missing information.

In this case, I think it was the latter. I tended to focus more on the purely thermal aspects of laser weaponry, considering it more important, but mostly disregarded the value of the mechanical damage mechanisms. Sufficed to say I've (hopefully) expanded my horizons beyond my previously incomplete viewpoint, and into something that better meshes with the overall picture. (Dont' worry, the chances for the 'megajoules' will still exist to infuriate others, it's simply not the be-all, end-all of lasgun firepower.)


The ultimate goal of the analysis remains unchanged: To provide a hopefully coherent and useful explanation of how I get the crazy numbers I get, how I think they fit into the larger scope, and why this shit happens the way it does. I also hope that providing explanations people can learn to use these numbers on their own footing without resorting to "Connor did it" appeal to authority-esque type BS - I honestly do hate that shit, because if I think I may not always be right, people shouldn't assume I am.

For posterity's sake the old thread can be found here. I'm going to have to go over that with a ifne tooth come at some point and correct/review the data there.


The "new" ideas are mostly pulled in part from Atomic rockets entry on energy-weapon sidearms, but mostly its from the insights of one Luke Campbell whose page I have noted in previous analysis if you haven't followed or noticed. Luke's page can be found here, and of particular interest as far as this little thread goes for the heat rays, which are more along the lines of my original lasgun ideas, blasters which are the 'pulsed explosion' style lasers first mentioned in Atomic Rockets, and the more recent and interesting antipersonnel page. The relevance of all of those as far as 40K weapons go (and whether or not they are actually lasers) will be yet another thing that will need to be discussed, but Luke's ideas actually mesh quite well into aspects of 40K in both 'modes.'


Other potential topics to discuss will be the nature of the lasgun, the various options and variety in the weapon (both deliberate and accidental), discussion why they seem to have so many differeing damage mechanisms (blaster vs heat ray, for example), a re-examination of the cauterization/burning issue (which formed my original calc foundations), other features of the lasgun (recoil, range, etc.), possible benefits of the lasgun over other weapons.


Luke's work has also inspired me to re-examine other energy weapons than lasers as well, so I may do some mention of plasma and meltaguns with regards to the whole "cremation vs other damage mechanisms" issue - while it tends to be more consistent than lasguns are, it's still worth mentioning.

This probably won't follow any consistent or "normal" pattern of updating like I sort of try to keep up with other things. It will basically be done at a whim and when I feel like I have something to add.

[Connor MacLeod]

Some corrections of previous ideas. I just had this lying on my HD for whatever fucking reason I had - I've long forgotten, so I decided I'd use it to show how I've been (HAH) reinventing my ideas (think of it as the sci fi fanboy equivalent of a franchise reboot, only with fewer explosions and less shakeycam)

Part of the reason is that they have multiple damage mechanisms: They have both heat and blast/shockwave effects (thermal and mechanical damage), and as described on the quite useful atomic rockets site, the mechanical damage effects can do alot of damage for very little energy. But lasguns also cause extensive cauterization and charring/burning, so the thermal effect must also be considered (and is in fact the most reliable mechanism I've found for calcing them.) Problem is, its been a bitch to figure out the exact temperatures one can associate with cauterization. Its not as if laser guns exist in this form, after all.

Kinda true, but not completely so. There are cases of lasguns causing purely thermal or purely mechanical damage in novels and fluff. Way back to 1st and 2nd edition lasguns have been alternately described as cauterizing wounds, but also as having the effect of a bullet, which wouldn't cauterize. And of course a number of cases where they may just drill a hole in the target rather than exploding stuff or burning it. So clearly the pulse-train typle lasers drilling holes can be applicable to lasweapons... and it has distinct advantages (increased ammo capacity , possibly increased ROF, etc.)

As I will describe later, I suspect that ultimately the effects we see depend on the design/configuration/settings of the weapon, and may be the result of design compromises, or desired effects, or various.

First, an overview of how they are desribed to work in the various sources. A lasgun fires a beam or bolt of massless energy (although there is some question to this, since some sources describe them as more "bullet" like, and others describe them as radiating heat or possessing kinetic force: it may be some are more akin to particle beams or a hybrid weapon.) The focused beam of energy strikes the target. The energy is delivered in a highly concentrated form, very rapidly, vaporizing the object (be it organic or inorganic) at the point of contact. This sudden, violent vaporization - a steam explosion, really - transmits thermal and blast ("kinetic", "concussive" or "mechanical" - terms I've seen to describe it, but for all intents and purposes it refers to the same effect.) effects into the target's surrounding matter (like with the asteroid vaporized in TESB.) In organic tissue, it is the water content of the body that is rapidly vaporized, causing the explosive shocks that propogate through the body, causing mechanical damage as described on atomic rockets source here

Note that as I mentioned, though, this method allows for little or no cauterization:

Again, I've concluded cauterization is less a criteria than I thought. Its not essential (or even really, desirable) for lasguns to cauterize - burns can carry nasty side effects that sometimes may be beneficial (such as their diffiulty to heal naturally), but in many cases you probably want the target to bleed out.
Also I think its worth noting that less emphasis needs to be or could be placed on "vaporization" - that could equally refer to vapour or plasma as described by the Death Ray page or atomic rockets sidearms. It may even be that scaling "efficiency" thing.. some weapons may merely "vapourize" but cause significant thermal burns as a consequence.

Additionally, the shockwave can induce heating in the surrounding tissue, resulting in cauterization and severe burning. It is worth noting that while this is probably considered to be the "usual" effect, it is by no means the sole mode of operation. Lasguns can and have operated in sustained mode, inflicting piercing or cutting effects, as well as purely thermal damage with minimal to no concussive effects. It is also worth noting that because of inefficiencies as well as the mechanical damage aspect, bleeding can still occur despite cauterization. The wound will just bleed much less in most cases. (one of the major purposes of Flak armor, in fact, is probably to minimize the concussive/shock effects as much as the thermal, since if the wound cauterizes it won't bleed, and suppressing the blast will remove the secondary bleeding.)

I now suspect the 'shockwave' idea was wrong. Not in that the shockwave might transmit energy or heat the surrounding matter, but that it would neccesarily cauterize. Flesh, being mostly water is both highly elastic (I now suspect it would be pushed out of the way or blasted apart before burning occurs ) and taking alot of energy to burn flesh (the specific heat of tissue is like 3/4 that of water.) What I now suspect may occur is more akin to either flash burning via a fireball, or scalding from expanding steam/superheated flesh - both of which are different than what I originally discussed.

As I mentioned, its hard to attach a temperature to cauterization. Specific heat is easy: water is 4185 J/kg*K, and flesh (easily googled) is 3500 J/kg*K - not dramatically different from one another. Melting point and boiling point aren't really relevant in this case, because the human body is 70% water for the most part (blood is higher at 83%, muscle and other tissue is around 75%, and bone is only 22%, but bones make up only 20% of the overall body mass, and blood less, but it works out to roughly 65-70% on average. Source here) Latent heat of vaporization for water is around 2.3-2.5 MJ/kg (depending on source). But we need the temperatures in order to complete the calcs (unless assuming total vaporization. That can be argued in some cases, and a fair amount of vaporisation probably does occur anyhow, but total vaporization is probably an upper limit for lasguns in general - though you could still argue that.)

Now, total vaporization is probably not only an upper limit, but an unlikely event in most cases. It's not totally impossible (as noted by Luke campbell here drilling a 1 cm wide hole through a target that is sustained/continueous rather than pulsed, it would take 40 kj, wich is close to an OoM more than the single digit kjs for pulsed lasers - conservative actually since the 5-10 kj pulse creates a 2 cm hole)

The closest before now (and what I always used) was the boiling point of water. We know from Ghostmaker that water will boil when hit by a lasbeam, and we already knew from numerous sources that vaporization can occur (including hitting snow or flesh), and partial vaporization will occur with boiling. Moreover, boiling point qualifies as a 2nd or 3rd degree burn (the cloeset point that charring can occur. As far as I can tell, cauterization is commonly associated with third degree burns, especially in branding. Technically, the term is referred to as "Scalding" for boiling liquid though.) This conclusion, however, turns out to be dramatically conservative (not that that's bad..) for various reasons. First and foremost, the "scald" temperature I used assumed a one second timeframe - realistically, especially considering the "explosive" effects, the timeframe would be MUCH shorter, which ought to mean the temperature should be considerably higher. Secondly, the images I have seen for scalding do not seem to indicate any real or significant charring, at least at that temperature. Third, the boiling point assumes very little vaporization occurs, which obviously isn't really going to be the case.

Like I said, "scald" injuries from boiling water/flesh, superheated steam, etc. probably are one possible cauterization/thermal damage mechanism. Such a lasgun would have to be deliberately designed to do such (with accompanying tradeoffs) or be a compromise between desired effects and efficiency
The "conservative" bit is sort of true.. but only in context of "purely thermal" damage.. and insofar as temperatures go. There are other factors (as I will outline later) that mean hat while temps can be higher, the overall energy compared to intiial estimates will not neccesarily be so.
Also, further and later research has suggested to me that temps to actually slow or stop bleeding (coagulation) don't need to be nearly that high.. you can, technically do it with as little as 60 degrees celsisus, although this may require longer times than a lasgun would have (surgically you do it to control the excess damage, which isnt a concern with military weapons.)

So a more accurate temperature is needed. Research on medical cauterization was time consuming, but did yield some results. The problem is, just becaue a temperature is stated does not mean its applying to the tissue. The cauters themselves could be very high temperature, but the temperatures applied to tissue need not be the same (energy balances, remember. Specific heat + a given temp over a certain mass for the energy input.) However, looking into medical cauterization, I did manage to find enough on tissue temperatures.

Which I did, but I suspect I was being overly literal again (coagulation can serve in many cases rather than cauterization, and wouldn't require the 100+C temps I mentioned in the past.) Another issue of course is the mass/volume of affected tissues.. my current ideas changed that rather dramatically as well.

*snip link and quote*)
Techncialyl the above refers to coagulation rather than cauterization, but the two I have noticed are sometimes used interchangably (and to mean much the same thing) In any case, as I bolded, temperatures of 150 C minimum are associated with "charring" and "dehydration" (IE damage to the tissues.) In terms of a medical surgery/cauterization, its desirable to limit termperatures to avoid this, but of course in a weapon such is not a consideration. So at a minimum, 150 C can be considered "charring/cauterization" temp.
link 2

As I said, now I consider coagulation and cauterization to be roughly equal for the purposes of calcs, which can mean temps as low as 60-70C suit my purposes fine.
I skip a bunch of quotes that really can be addressed the same way as above, so I will just delete them and move on.

This does indicate that at lower temps the sort of desired destruction we see can START to occur, however, as noted above, much higher temperatures have been used in surgical practices, so its not a absolute thing (indeed, if this were sufficient, they'd have no need for 100+ C temps, would they?) This could be on a highly localized, or a long term scale (alot of the surgical procedures rely on very sustained applications.. many seconds or minutes.)

Ah, as I said I was much more narrow in my thinking back then. I suspect that temperature depends on alot more factors... If the lasgun turns the flesh charred and black (as it does with some) then higher temps might be warranted at least to some depth. But lesser burns coudl serve equally, and may not require as high a temperature. Hell, the depth of tissue damage cna vary.. for all we know the high temp burns may be very shallow, while the lower empreature ones are deeper.

This is precisely a description of what I conclude a lasgun would do (and fits the descriptions in the novels.) "tissue surface temperatures" indicates wide-spread effects (the cauterization occurs on the edges of the wound, remember, so the average volume of the wound needs to be around 300C). Also take note of the "tissue and bone charring", and the "blood plug" that temporarily stops bleeding, but can be broken open again. Cauterization is hardly consistent or perfecT (variable outputs, body armour or lack thereof, glancing or direct hits, etc.) so some owunds could be MORE cauterized than others, or more violently broken open (by motion, jarring, the explosive kinetic effects, etc.) The only real difference is volume (its still a medical procudure we're talking about, so teh damage is much more localized. Lasguns blow out fairly sizeable wounds, relatively speaking.)

I do admit it still sounds alot like some descriptions of lasgun effects, but it doesn't really describe them all. The real flaw though, I think, was in the volume/mass I used in the cacls. Before, I suspected that the energy radiated out from the beam to more or less uniformly affect the entire volume. A normal laser would not do this, but a sufficiently magical "laser" could dpeending on how you envisioned the thing operating (and its not imposisble for lasguns to be "magical" lasers)

More probably though, what I should have been calcing was the surface area of the wound cavity, and an esimated depth. I suspect no more than a few millimetres woudl be sufficient for the purposes of cauterization, esp incomplete cauterization.

This is really just an illustrative sampling. Sooner or later I'll get around to describing in more detail what I think probably will occur.

****
Part 2 - reassessment of some old calcs and quotes - mostly serving as illustrative examples. I might redo other calcs at some point as mood and time permit.

The short duration high energy [lasgun] beam produces such a rapid temperature change on the target's surface that it vapourises in a small explosion.

Only including this to verify the "vaporization" aspect. Doesn't tell us the amount of vaporization occuring, but it ought to occur along the path of the beam and the surrounding area (a diameter of at least several inches, and probably 4-6 inches depth) Given the "300-400 K" temps implied by the quotes I already provided, though, its quite probable that a significant amount of vaporization will occur once the water content in the body reaches boiling point (every degree beyond boiling point will result in vapor forming, just like when a pot of water is brought to the boil.)[/quote]

My intiial assumption is one way to calc it, but this could also descrbie a rapid pulsed laser as Luke Campbell and Dr Schilling described too, although it implires only a single pulse rather than a series of pulses. Single explosions are more "greande like" and would produce bigger holes in order to get any depth penetration.

One interesting possibility is that lasguns are "single pulse" while hellguns (which have considerably better penetration" are multiple pulse trains.

Las weapons work by firing a blast of highly charged light which transforms into heat and kinetic energy upon impact, causing tissue damage and burning.

This confirms that there is both a thermal and 'kinetic" (ie mechanical/concussive) damage element to las weaponry, and that thermal effects (burning) is a significant partt of the damage mechanism.

The charged light bit sounds odd (magicla laser IoW) but this context implies at least some lasguns are more "hybrid".. trading some efficiency in mechanical damage (creating a shocwkave or explosion) for thermla effect.

"Tarok slumped down behind the rock.

...


As the stones pattered to the ground, a Deathlight flashed the stunted bushes itno flame. Tarok sprang up and fired at the Brannath who had just given away his position. The man fell forward out of the bushes with a fist-wide, smoking hole punched through his body from front to back. Strange, thought Tarok, that there is no blood.

That thought almost cost him his life. He almost failed to notice the shadow sliding over the rocks behind and right of him. The rock glowed and began to melt as he dived away from the beam of the Deathlight. The Brannath was not quick enough with his second shot.

Then, on all sides of him, the air was shot through with the deadly bright rods of soldier-lightning.

...

They were watching through their magic, he knew - the same magic that made the Deathlight spit its soldier-lightning.

I'm going to ignore the rock melting since that doesn't change much. But to put a 10 cm diameter hole 20 cm long through a body could eaisly be handled by 10 kj at least, certainly well in the double digit KJ range. But what about cauterization? If we assume 1-2 mm thickness and a 150 C temp it would only take 30-50 kj to achieve the effect. If we go with coagulation temperatures it would be 1/2 to 1/3 that figure, but I suspect coagulation wouldn't be as uniform or reliable, so it might only stop or slow bleeding, but nothing says it has to be 100% perfect either. Partial cauterization has happened with las-weaponry as well.

It [the lasgun] fires an explosive energy blast with a similar effect to a bullet or small shell.

Simple: single digit kj (if efficeintly done) to double digit kj (if not) can cover this easily. Alot of it depends on the actual mechanism to simulate the effect, efficiency, whether or not it inflicts any thermal damage (which may or may not contribute - still up in the air about that), and the kind of bullet/shell is being talked about (it's kinda open ended after all!)

I suppose for example we could use the "autogun" from IA5 as a benchmark something like a 7.62-8.25mm bullet (something akin to this on the high end methinks.) would be 10-15 gram bullet at 820 m/s or so is somewhere between 3-5 kj per shot. Which is actually pretty damn powerful.

Danil Vorens lowered his smoking laspistol and returned his attention to the viewscreen before him. A stunned silance filled the defence control room, the technicians agog at what had just happened. Lutricia Vijeon stared in open mouthed hoor at the corpse lying in the center of the room with a ragged hole where its face had been.

again single or double digit KJ (equal to a 7.62MM nato or .50 BMG) could probably cover this. It's not as great as "megajoules" but as far as bullet-like or explosive damage that's pretty impressive.

The bolt impacted. It tunnelled and exploded. Flesh and bone or a vital organ erupted. It was ever this roudy way. By contrast, laspistols were silent in operation. If the aim was inaccurate, the scalpel-blade of energy soon dispersed. Whener a las-pulse met its target: such lacerating flare-up, such a scream of agony, if the victum still had the breath and lungs and heart to scream. Perhaps ten of the pilgrams had fled. A score more lay dead or dying, almost all thanks to the laspistols."

Double to triple digit kj, depending on how big the hole is - can easily cover this. This might be either a high end laspistol, a high-powered power cell (overcharge or hotshot), or it might simply be a max setting shot. Double digit probably more than suffices to penetrate deep enough and make a big enough hole to destroy the lungs (we're talking a head-sized hole, easily) Hell if its done right it might even be single digit, although I'd still say 10-20 kj at least is more likely. If we get into triple digit kj or even megajoule (possible depending on the variables you input - I've done that before with this one!) it likely set at a high power setting (or maximum power, take your pick.)

A las-blast felled the armsman beside Semper. The captain grabbed the man as he fell, intending to drag him into the bay, but then found himself staring into the excavated crater of the man's skull, where the las-shot had blown half his head away.

Again single digit kj can cover this, as far as explosive damage. If we factor in cauterization it probably would fall into single or double digit kilojoules. In my mind this prorbably represents the lower end of the lasgun scale, or lower settings.

The flickering of the daylight was being caused by bright las-roudns passing over us, almost invisible against the hard glare of the sky. Then a shot stung by against the bricks and I saw it clearly. A dart of seething fire, tinged red, the size of a man's middle finger, so bright it hurt my eyes, so fast it was barely there.

Diameters have varied from several cm (most common, assuming the visible component means anything) to a couple of millimetres.

But Mktag had been shot. Right there in front of me. He fell at my feet, his heels drumming the ground, his hands spasming. A tiny plume of smoke spiraled up from the little black hole a las-round had made in his forehead. There was no blood. The shot had cauterised the entry wound and it didn't have enough power to exit his skull. Its heat and force had been expended getting into his cranium and incinerating his brain.

It was quite simply the most awful thing I have ever seen. His body thrashing, trying to live, the brain extinguished. I think if there had been more blood, more obvious physical damage, I could have coped better.

But it was just such a tiny hole.

Originally I assumed that this was total cremation. It may be, but it would require a fairly exotic/magicla mechanism to pull off, because cremation would mean vaporizing a large amount of water.. which would at least rupture, if not explode, the head.. and we aren't seeing that. PErhaps its a POV thing (the person can't see the back of the head) but erupting gore is not something one would miss.

I should note that it is possible for thsi to happen - codex Eldar and the Blood Angels novels both have described lasguns vaporizing brains, so this interpretation is still technically valid. However, for conservatisms sake it probably is better ot assume "incineratE" means badly burn.

According to this link the human brain has a surface area of ~2500 square cm. ASsuming severe second or mild third degree burns (say 20-50 j/cm^2 - which would yield 50 to 125 kj roughly assuming the entire surface area was burnt - as an order of magnitude calc it works.
Of course if we do it my "traditional" way by temp and weight.. 1.3-1.4 kg brain at say 30-70C temp increase (to say 60-100C) - with that "mild" assessment, it would take "only" 100-300 kilojoules or so to incinerate the brain. Again as a rough ballpark figure it works.

And lastly, the helmets:

I pull off my helmet and look at it, still a bit dazed from the hit. There's a charred gouge just where my right ear would be, almost burnt through. I poke at it with my finger and I'm shocked when my fingertip passes straight through. The las-bolt had been within the thickness of a piece of parchment from actually getting through!"

The laser burst punched through the top of the bandit's bowl-helmet, presneted as it was by his head-down appraoch. The shot probably passed down through his skull, his neck, and his torso, following the line of his spinal column, Merrt thought, as the figure dropped stone dead in a crumpled pile.

[/quote]

I went with 3 cm depths before.. Let's assume 1 cm adn go from there. Using the Death ray page's laser calculator, the closest to carbon is nanotubes (which could be the helmets) is 10 kj per cm of epentration (assuming a 1mm hole diameter. anything up to a few cm might be several times that easily)

The second one is interesting because it not only penetrates the helmet, but moved entirely through his head and upper torso some 50-70 cm of penetration. Now as I noted before Luke Campbell's hypothetical lasers for a 5-10 kj pulsed laser train could penetrate some 50 cm (2 cm diameter hole) whilst a 40 kj CW laser could drill a 1 cm hole through a person's torso (20-30 cm maybe?). That easily means high single digit kj (at least 7-8 kj) if not many tens of km (for either pulse or continuous laser) and this is in addition to the helmets.

note that such insane penetration isn' t unheard of - we saw lasgun shots in "Death World" penetrate multiple torsos quite easily.

Another small addition is temperatures and times associated with scalding. I figured on this as a supplement/altenrative to my cauterization figures - especially since a fair bit of steam or boiling water has been associated with lasguns.



scalding times

This shows how the time to burn increases exponentially with increasing hot water temperatures. Look at 3rd degree burns for adults. Shows 3rd degree injuries occur in about 1 second at 160F, 5 seconds at 140F, 9 minutes at 120, 6.7 hours at 110.

scald chart again

scald 3

At 160 degrees F-------------------------------------------------------1/2 second
At 150 degrees F-------------------------------------------------------1-1/2 seconds
At 140 degrees F-------------------------------------------------------5 seconds
At 130 degrees F-------------------------------------------------------30 seconds
At 120 degrees F-------------------------------------------------------5 minutes

Mainly useful data on scaling. Note that around 160-170 F or so seems to be a good time for rapid burning, as long as the duration isnt too short. I dont think we can predict very much beyond this, although i think inflicting the burns in 1/2 to 1/4 of a second (within the bounds of normal human reaction times) should work, especially if resulting froma a higher temp (at or close to the boiling point should work pretty well for this.)

[Connor MacLeod]

In an attempt to foist off yet more of my "earlier" attempts at silly lasgun analysis, I present more of my past obsession with temperature numbers, surgical cauterization, laser surgy, and suchnot. Also some stuff not even pertaining to medical stuff regarding steam explosions (which actually is probably more relevant and useful.) I actually had a diffrent set written up part way when the power went out in the complex, so I gave up and settled for a shorter one.

More laser temp stuff.. google books again

Thre different methods of thermal tissue destruction can be distinguished, depending mainly on the exposure time to an increased tissue temperature:

1. Hyperthermia at temperatures of 42-45C, causing reversible damage to cellular enzymes, that may become irreversible after longer exposure times (25 minutes to several hours).

2. Coagulation and vaporization of tissue water at temperatures of 60-140C, causing protein denaturation, hyalinization of collagen and cell shrinkage, which can be observed macroscopically by tissue blanching.

3. Carbonization and albation at temperatures of 300-1000C, causing charring with increased light absorption and smoke generation.

Which of the above thermal effects will occur depends on the laser treatment parameters applied and the optical properties of the tissue involved. Thermal interstitial laser destruction has mainly been achieved by either hyperthermia or a combination of carbonization/ablation and coagulation.

Now obviously you can see what drew me (rather mindlessly I admit) was the focus on temperatures for calc purposes. The reasons why probably made sense (they fit the effectS), but the volume/mass of tissue I applied it to wwas what was wrong. In most lasgun wounds where significant burning/cauterization occurs you typically have the surfac eof the wound charred/carbonized/cauterized, and the effects may go to varying depths depending on the instance. In some cases you may actually have cauteriztaion/charring/carbonization of more of a volume of material (EG brains from a headshot) - especially with a powerful weapon (EG hellgun or hotshot) but probably assuming that a fist sized chunk of flesh was totally burnt always is not always the case - we get casues of explosive, bloody damage, or perhaps only partial cauterizaton (which could just be third degree burns and coagulatiom or superficial cauterization rather than full volume, deep tissue damage.) - this just shows that context and paying attention to the how, and why, and what - matter as far as calcing a lasgun, and each example has to be judged on a case by case basis. Some may be partyl or mostly thermal, others won't.

Note that if you try calcing a 1mm or so deep, 1 cm x 1 cm square "burn volume" (assuming 700 kg*m/s density for flesh) at the coagulation temps (aruond 140C) and a specific heat of flesh a around 3-3.5 kj per kg*K you get a value approximating 30 J per square cm for "fthird degree lash burns." Even if you reach up into carbonization (300+C) you still stay well within that threshold hell even 1000C won't get you more than 200-250 j Cm^2, which is probably more like severe third/fourth or fifth degree burns, but wouldn't be beyond what we know lasguns can do.


ongoing laser surgery stuff

When laser energy is absorbed by tissue water, the temperature of the tissue increses, which usually results in vaporization, or ablation, of the tissue proteins, with the heat being dispersed as steam and not as thermal trauma to tissues, according to a laser manufactureer....
..

If the tissue is heated without vaporization, tissue temperature increases dramatically to over 600C, and charring can result. When this occurs, thre zones of tissue damage result. The first is composed of carbonized eshcar. Beneath this is an area of coagulative necrosis. And finally, there is a sheath of edema that surrounds the ablated site.

Interesting about this is that the tissue "ablation" or steam does not seem to be dangeorus per se. Of course alot of that depends on how "hot" the gas itself is, and how quickly it dispereses, and suchnot. I believe that "heating without vaporization" or boiling is technically superheating (no phase change occurs to carry off excess heat) and that can be.. explosive (eg superheated water/BLEVEs, etc.) Since some forms of lasgun damage seem to represent tissue steam explosions rather than a pulse-laser train of explosions (EG Luke Campbell's "blaster" death rays) this may represent simply a "kind" of lasgun damage mechanism (maybe it depends in the capabilities of the manufacturer, or the setting or kind of enemy faced.)

This is also somethign that tends to make me more cautious about temps than I was used to - the thing about tissue temperature is that it doesn't really take into account the volume being heated - if it is a steam explosion (for example) you might have a very small volume of tissue very briefly raised to high temps, but that won't last forever for obvious reasons, so the 600K (for example) may represent "before" rather than "after" effects. As I've noted elsewhere, it isnt neccesarily for tissue tmpe to stay nearly that high to cause effects like coagulation (60K suffices for that.)

If one can reduce this area of thermal damage, more rapid heating is seen and less scarring occurs. One way to do this is to use a shorter laser exposure with a very high power density. In this way, the same volume of tissue is vaporized as with a longer exposure, but at a lower power. This means that there is less thermal damage to the tissues. With high-energy gain-switching CO2 lasers surgeons now can achieve very high energy levels in very short periods of time in which each individual pulse of energy never exceeds 600 milliseconds, which is less than the thermal relaxation time fo skin tissue.

In other words, photomechanical effects, akin to what Luke Campbell's "Blaster" death rays describe, although the "explosive" effects seem much more mild than what Luke aims for (since this is for medical rather than military reasons, this makes sense.) Of course it is not just timeframe that matters for creating explosions - volume of material affected and intensity matter greatly too in order to simulate explosive effects with an energy weapon.


you know what I am describing

As heating occurs and the tempreature of instantaneous cell death is reached (65C), coagulative necrosis occurs. At temperatures over 100C boiling of tissue water begins, leading ot drying or desiccation of the tissues. The more the temperature exceeds 100C, the faster the boiling and desiccation occurs. Once desiccation occurs there is a large and dramatic increase in impedance. Charring does not happen until temperatures reach about 200C.

Electrocautery, but applies

Again an approximate "60c" figure (they say 65 here, but remember that the coagulation range has gone as low as 50C.. that it might go higher than 60 C seems a reasonable variance.) and coagulation starts occuring.

This quote also seems to corroborate what I hinted at earlier - temps over 100C seem to reflct a higher initial "input" of energy, rather than a measure of the results after, so one has to be careful to what sort of volumes one is using these temps on (example the "charring at 200C thing" - charring likely occurs because all the water in the tissue has boiled off, and no longer acts to absorb the heat and insulte the tissue, you can boil off the water with lower tempreautres ove ra longer period, within parameters established by the thermal properties of the material. So the 200C "charring" value is very context-sensitive, quite likely in terms of time and possibly volume - eg you heat a certain volume of tissue in a certain length of time to 200C and it boils off the surrounding tissue at a certain rate, or whatever. Besides beyond 200C we're getting into "superheated steam" territory again which means once again a likely steam explosion of some kind.)

. Another reason why perhaps using flash burns (At least as a double check or an alternative) may also work.

The observed thermal effects are temperature-dependent. Temperatures below 40C do not produce significant cell damage. Temperatures above 40C cause reversible cell damage, depending on the duration of exposure. Temperuatres above 49C cause irreversible cell damage, and temperatures higher than about 70C coagulate tissue by the conversion of collagen to glucose. At approximatley 100C, intra- and extracellular water changes from a liquid to vapor state (dehydration). Tissue charring occurs at approximately 200C

A high-frequency electric current divides tissue by eating the cellular fluid to more than 100C so rapidly that there is no time for the tissue water to vaporize slowly. A high vapor pressure is created that "explosively" disrupts the cells and tissue.

The lattter bit mainly confirms what I suspected about steam explosions. The above would seem to confirm my caution about applying temps nowadays due to context. EG I might use "charring" in the context of what happens to the edges of a lasgun wound, but not neccesarily to the volume. It depends on the weapon and how it interacts with the target, basically, and generalizing as I have done in the past is foolish and silly.

more, but with general ablation stuff.

Optimal ablation results are achieved when local temperature is maintained between 60 and 100C, with nearly instantaneous tissue coagulation necrosis. Lower temperatures require longer exposure time to achieve the desired result. For example, at 46C at least 1 hour is required to ensure cell damage. Conversely, a rapid increase in local tissue temperature above 100C causes tissue charring that limits effective coagulation necrosis.

Again the importance of thresholds, and the relationship betwene temperature and duration as far as energy input goes. Again how this applie sto las weapons depends entirely on the kind of weapon and the mechanism used (more applicable to highly-thermal applications of damage, rather than purely mechanical or cases involving bleeding wounds.)

This also reflects the caution in using temps since this is largely medical and not military applications - it is not possible to hold a laser on target for an hour ot burn it. I suppose if I did more in depth reading or analysis I might turn thi sinto something usable, but I'm not sure its something I can or should try to dumb down (either because I fuck it up, or someone doesnt understand it even if I do.)

yet more fun tissue stuff

The various affects of Ultracision in the tissues are achieved at temperatures of no more than 150C. Coaptation leads to fragmentation of proteins and coagulation to denaturing of protein compounds. Cavitation occurs at body temperature, coaptation in the range between body temperature and below 100C, and coagulation at a temperature of up to 150C. In this way there is no burning, carbonization, or smoke formation, as with cautery or the laser when temperatures of up to 400C may be reached.

Temperatures of over 150C, which cause burns and/or carbonization, do not occur when Ultracision is used. Conversely, to gain biologicla effects (e.g., hemostasis, tissue cutting) comparable to Ultracision using HF cautery or a laser can only be achieved at temperatures greatly in excess of 150C

Fig 2.22 Mentions ultracision operating between 50-100C with effects of Dissection, cavitation, coaption and coagulation at 100C. At 150C to 400C (Electorsurgery and lasres) desiccation and charring occur, respectively.

Yet more silly tissue stuff. note they draw distinct differences between kinds of effects.

Coaptation is (more or less) when separated tissue is drawn together in a wound or fracture. In this context I would think of it as "fusing". Cavitation is just as it sounds - the pressure sbuilding from the formation of steam/vapour inside the tissue from the heat. Coagulation I've already described. This seems to suggest a kind of "non burning" cauterization, (as opposed to the sort that has smoke, carbonization, charring, etc.) It's something useful to consider, especially for cases of "partial" cauterization occuring or in no bleeding occuring from more "explosive" damage.

and yes. I was VERY obsessed with temperatures back then trying to figure this all out. Things are so much simpler now!

Temp (C) Visual change Biological change
37- 50 swelling Heating, retraction, reduced enzyme activity
50-65 blanching Coagulation
65-90 white/gray Protein Denaturation
90-100 Puckering Drying of tissue
>100 Drying H2O boils, cell explosion
>150 Charring Carbonization
300-400 Blackening Smoke generation

Useful (sort of) temperature charting stuff. Rather interesting that here they draw differences between boiling/cell explosion, Charring/carbonziation, and actual blackening. This might be useful in context of measuring "edges of wounds" like I did above (assuming say millimetres depth over a certain surface rea) to calc in some way the energy the lasgun bolt might have possessed (although that doesn't neccesarily mean an EFFECTIVE las-weapon - it could be a very inefficient or poorly designed weapon that relies on large inputs of energy to cause explosive damage, for example. Or it may even deliberately be made to create thermal effects to induce burns for some reason -eg to counte regeneration or destroy ork spores that might be released due to injury, for example.)


Tissue laser interaction pdf PDF/url]

Hyperthermia: meaning a moderate rise in temperature of several ºC,
corresponding to temperatures of 41º to 44º for some tens of minutes and
resulting in cell death due to changes in enzymatic processes. This is a difficult
procedure to control and so it is little used in practice.
n Coagulation: refers to an irreversible necrosis without immediate tissue
destruction. The temperature reached (50º to 100º C) for around a second,
produces desiccation, blanching, and a shrinking of the tissues by denaturation
of proteins and collagen.
n Volatilization: means a loss of material. The various constituents of tissue
disappear in smoke at above 100º C, in a relatively short time of around one
tenth of a second. At the edges of the volatilization zone there is a region of
coagulation necrosis: there is a gradual transition between the volatilization and
healthy zones. The haeomstatic effect is due to this region of coagulation
necrosis. If the volatilized zone has a large area of some millimeters in
diameter, it is possible to destroy tumors bigger than those treated by a simple
coagulation. If the volatilized region is narrow, a cutting effect is then obtained.

Useful definitions since they involve some timeframes, especially in terms of coagulation. Note that given the "scalding" figures I tried mentioning before, we might usefully figur that some measure of coagulation could occur with a steam explosion if it produces sufficient high temperature steam 1 sec to .5 second scald burns correspond to a temp around 60-70C for coagulation.

"Volaitilization" (which brings back memories of Lensman stuff I did with teleros) is interesting since it is fraction of a second. Note the refrence to "cutting effect", which might be useful for those particular kinds of calcs (like in First and Only). Otherwise I think we're more or less saying "steam explosion."

The 40-44C figure is not really useful for most part, except maybe as a lower limit calc but no real point to doing that.

[url=http://www.ece.arizona.edu/~BMEoptics/p ... aleval.pdf]a bit more

The following histologic markers of thermal damage were
evaluated: 1) epidermal fragmentation and loss; 2) epidermal
and dermal vacuolization due to tissue water vaporization;
3) cell and nuclear shrinkage, spindling, and hyperchromasia;
and 4) collagen thermal coagulation changes including
hyalinization and birefringence loss (Fig. 3).
Water-vapor vacuoles form in tissues as temperatures approach
100 C. Rapid expansion of superheated steam in
the vacuoles will cause explosive fragmentation and loss of
desiccated tissue (“popcorn” effect). Individual cell desiccation
and thermal coagulation of the cytoskeleton are responsible
for cellular shrinkage, spindling, and hyperchromasia. Hyalinization
(glass-like appearance) is thermally mediated collagen
transformation from distinct fibers to an amorphous sheet of
denatured protein. Thermal collagen denaturation also causes
loss of the bright birefringence image of native collagen when
observed with TPM. All of these histologic changes reflect
thermal injury [27].

All this comes to is really "Steam explosion" although for medical purposes the input of energy is controlled to control the violence of the effect. I like the term "popcorn" effect, since it gives a nice visual about what we might be expecting to see and contrasts the otherwise "high explosive" fffect we might think of in context with "explosion." (popcorn popping "is" a sort of explosion after all.)


Steam explosions:

CANDU reactor article on steam explosions

It is a vapour (steam) explosion, i.e., a rapid boiling process in which steam is formed sufficiently
fast to produce a shock wave. When high temperature fuel material enters the water, it is initially
separated from the water by a thin vapour film. In this state, the hot material breaks into a large
number of small particles. If and when the explosion is initiated, heat can be rapidly transferred
because of the large surface area. However, steam explosions are notoriously inefficient compared to
chemical explosives such as TNT. For example, a typical molten aluminum-water explosion might
produce a shock wave of 100-200 pounds per square inch (psi) as opposed to 100,000-200,000 psi
for a solid chemical explosive. As discussed earlier, this is demonstrated by the fact that casualties in
foundry accidents are generally the result of severe burns from the molten metal that is sprayed by
the explosion and not by concussions from the shock wave, as is the case with chemical explosives.
Such foundry experiences have shown that the "blast" damage is generally confined to sheet metal
walls and roofs, which is also indicative of the comparative weakness of shock waves produced by a
steam explosion.

This isn't really pertaining to tissue per se, but I liked it because it helps explain "steam explosions" as they can occur and how they may compare to more "TNT-like" explosions (which is what a "blaster" lke Death ray is trying to simulate.) This just goes to show why context matters for all this - not every lasgun wound is a steam explosion, but not all of them are going to simulate TNT just BECAUSE vaporization occurs. Indeed "explosion" by definition can be highly variable and not all will produce a nasty, high speed shockwave like HE does.

[Connor MacLeod]

Another bit I had worked on and left unfinished... this was less calcing and more "explaining in a long winded way to hear myself talk" sort of thing. i try explaining why I fixated on certain numbers (badly) and explain the silliness with dallying in cooking numbers (which I have long since gone from) This was back in Sept of '09 btw.. most of this is years old I should say, which shows you how much time has passed for me to reconsider my ideas, and why revising is important.

(PS: Feel free to laugh at the cooking bit. I look back on that and I feel both amusement/laughter and horror/foolishness at even considering it. But hey, noone is perfect, and at least I'm willing to admit to foolish and stupid ideas in figuring this stuff out. That's more than some so called "analysts" I've seen do. Important lesson: If you ever start taking this shit too seriously that you can't laugh at yourself for things that turn out stupid ideas, you've become too damn dogmatic and should stop doing it.)

****

Some more on Cauterization and the baselines used for lasgun calcs. Its messy doing calcs like this, especially for someone who is more of an amateur than someone like, say, Mike. I tend to go for more of the "MythbusterS" approach - I look for creative ways to do the analysis and come up with as close an approximation as I can, and to get the results that are broadly consistent (within an order of magntiude is good, given variables.) This can sometimes mean I look at unusual topics for ways to derive the values for my calculations.

In this case I've looked at cooking. Not all meats really correspond to human flesh (steak for eaxmple) but its known that pigs (or pork) does correspond close enough (for our purposes) and in general the differences aren't significant enough to be a problem for my purposes (plus/minus say ten or twenty degrees) Why I look at cooking is quite simple.. it can provide us (broadly) wth the sorts of temperatures that cook flesh, or sear it, or char it outright or burn it away. For our purposes, searing and grilling and frying are the best approximations (in terms of results, not time.) Searing requires boiling off most of the water content in the meat (or rather the flesh) in question before you can start to burn or char it.

Frying, you ask? Well, human body does contain non-insignificant quantities of fat, and like in cooking you can get flesh to "sizzle" and cook" - this could also account for examples of flesh "melting". Further analysis (to be done in the future.. as soon as I sort out al lthe links) with direct effects of lasers on tissue HAS indicated it is possible to "melt" flesh, but the detaisl behind it remain a bit fuzzy to me even if the tremperature thresholds don't. How that interact siwth cremation, as well as addressing the cauterization issue further ( as well as other terms like charring) will happen later.

As a low end figure, meat is considered cooked when the internal temp reaches something close to K. This really isn't "blackened", but it works well as a lower limit (and in reality you wouldn't get large scale cauterization in the body.. only the surface layers of the wound.. as a rule my calcs tend to only work with the volume "blasted" and not the surrounding material, but these calcs could be used in the surrounding material. They also work well as very conservative calcs in and of themselves.)

As an aside, we can look at scalding-burn temps and those needed to inflict third degree burns on flesh via superheated steam and the times to cause it. Interestingly, this does seem to hint at similar results to above. (inflicting severe burns isnt neccesarily going to cauterize, ,however.)

*****

This next unfinished bit seems to be an attempt at outlining the various advantages of laser weapons (instead of raw power) over other kinds, more than the ones typically outlined for lasguns in the fluff. It also seems to be designed to encompass a broad idea of the variations they can encompass as well. I may come back to this at some future date, time and interest allowing.

You can also see the genesis of my idea of "thermal vs mechanical damage" which I'd been wrangling with since Luke had begun his site (and Nyrath had broughti tup to me, as well as Nyrath's little sidearms page.) Again interesting largely in the way my mind has meandered aimlessly, flailing about until I hit upon an idea that worked. hopefully my "fourth edition" efforts at this analysis will be more lasting and coherent than these previous attempts


*****


Lasguns are very versatile weapons. Much moreso than projectile weapons. With the ability to change fire settings/modes as well as charrge settings, they can perform many different feats. They can fire in single shots, or they can fire a continuous beam that can cut/slice the enemy. They can fire an explosive burst that does mechanical damage like an explosive (blast effects) or they can do thermal damage or somewhere in between. They can fire on varied power settings for different enemies, trading greater damage and range for more shots or vice versa. These are things most projectile weapons cannot match.

Many soures have specified charge settings: various Guard novels (Desert Raiders, Rebel winter, etc.) the 3rd edition codex mentioned charge settings, as did the Uplifting Primer. The Ghosts novels had it, its mentione din the novel "Space Marine", and so on and so forth. "full auto" settings have been mentioned in too many novels, but the "continuous cutting beam" mode has been shown in the Inquisiton War novels, the Gaunt's Ghosts novels, the Grey Knights novels, and so on...

The versatility extends more form there. We also know of lasgun variants- more compact verions for close in fighting/urban warfare (bullpup or carbines) as well as the long-las. We also know that lasguns can incorporate different powerpacks with varying ammo capacity and even power outputs (most notably the overcharged packs and the hotshot packs, which come in different flavors.) This adds further versatility to the lasgun, and the plug and play modular nature of the lasgun can make modification quite easy. Hell, you can probably have backpack mounted power packs (we know that hellguns have them, and older guard codexes, most notably the 3rd edition listed Guard regiments that seemed to use a backpack power source. And plasma and melta weapons have also had backpack sources. And the "Cities of Death" add on mentioned that its possible for lasguns to be plugged into stationary power sourcees rather than use powerpacks..)

This does, I think, carry implications for the composition of Guard units and how they differ from modern ones. With the right settings the lasgun can probably fill the role of full powered rifle or battle rifle, machine gun or SAW, or even marksman rifle (higher settings can correspond to more powerful ammo cartridges, like between 5.56mm, 7.62mm NATO, etc.) and the continuous beam mode would work well for most machine gun type roles. At most, you would maybe need to issue the aformentioned backpack power source, or just a higher capacity power pack (which we know exist) or perhaps a few other modifications (a different barrel for longer range firing, perhaps).

Besides, if (for some reason) the Guard needed to carry a LMG analogue there probably are bolters, large autoguns, autocannon, and stubbers (there are guardsmen who can carry autocannon and stubbers easily, after all).


As an aside, we have varied accounts of lasgun rate of fire, with the uplifting primer being the basic (and slowest). Initially I felt this might have been absurd, as many other novels (Soul Drinkers, Grey Knights, Cain novels, Ghosts novels, Last Chancers novels, etc.) have implied greater Rates of fire are possible (though 13th Legion also mentioned 5 shots/sec too..) Currenlty, I tend to think there probably isnt anything wrong with the slower ROFs, for the following reasons:

- Lasgun shots, generally speaking, are perceptible to the human eye. Disregarding the issue of being seen, the fact they can be seen indicates they persist for fairly long periods of time which will limit rate of fire (1/3 to 1/5th of a second would seem likely.

- variable settings can mitigate the need to get "more shots" on target.

- continuous beam settings make rate of fire pretty irrelevan

given human reactions (even the probably enahnced reactions of some/many 40K humans) You probably don't need more than half a dozen shots a second to "hit" a target" anyhow, so higher ROF is probably academic for most cases.

Mind, ,there probably are some cases or reasons you might want to have a higher ROF for lasguns, so thats probably why versions like that exist (suppressive fire or "spray and pray" where you don't want it focused in a continuous cutting/piercing beam, for example.)

Thermal vs shock damage and energy yields.

It's a not so secret fact that even though I've established some fairly consistent (depending on who you ask, as there are always some who insist I am biased and exaggerating things) calc ranges for lasgun capabilities, there is still some room for variation and even a little differences in energy outputs, and that these variances may seem like inconsistency. At least, I generally assumed that in the beginning. But in truth, the idea of "low" energy (kilojoule range shots) is not inconsistent with megajoule range shots either, and the reasoning is simple and obvious - it comes down to damage mechanisms.

We know that lasguns can produce a wide variety of effects- they can make narrow holes, they can produce sustained cutting or melting beams. They can explode things messily (limb,s heads, etc.) They may cauterize fully, some, or not at all. They may boil, char, sear, melt, or whatever. It seems safe to say that it is possible for lasguns to do purely thermal (burning, melting, boiling or vaporizing), purely mechanical (IE shock effects or simulating bullets or explosives as per Atomic rockets and Mike's site via extremely rapid, explosive vaporization). or a combination of both depending on make and model and the settings and design of th eweapon. The lasgun would be designed to handle both sorts of firing, which we could consider as "pulsed" and "continuous" modes.

From a versatility standpoint, it makes sense. Some enemies may be more vulneralbe to explosive or shock effects as opposed to thermal, while others may need to be thermally damaged, so being able to do both is useful. You may need to conserve ammo, which lower settings that rely more on mechanical effects can allow. Lower settings would also facilitate fully automatic fire more effectively as well. Indeed, there are tradeoff considerations behind such a design - tradeoffs in power versus ammo capacity, firepower vs heating (which could effect rate of fire or overall firepower, etc.) and so on.

We may even go so far as to speculate that different "modes" may also have different values for a given charge setting - a "maximum" power pulsed shot could still carry less energy than the shot in sustained mode (which may laos help explain peculiar phrasing between single shot and full auto apparently consuming more power, if single shot was a pulsed one) Pulse vs beam/sustained may also affect rate of fire (pulsed modes could have greater numbers of shots than sustained for example.)

[Connor MacLeod]

Oh yeah: Someone asked me on SB a bit back about my change in stance on calcs, and seemed to have the impession that I was now saying lasguns were "all" kilojoule range, or something like that. Just to clarify - I'm not saying one set of calcs is automatically the "standard" or the other. I'm saying that there can be advantages and drawbacks to each end of the range, and that it will really depend on the circumstances and variables. A shot more in line with kj range can be quite useful in terms of rate of fire and cooling, number of shots, etc. It may reflect either a low powered laser weapon, or a low power setting.. but it can also mean a very efficient lasgun damage mechanism. Higher outputs could mean more "damage' in other ways (burns, cauterization and steam explosions) but it also has some hefty drawbacks (fewer shots, cooling issues, and less efficient mechanism). It may also mean a very powerful las-shot (EG hotshot round or hellgun round) if the weapon is sophisticated enough. It may even be that they WANT lasers to inflict burns for some reason (ork regeneration or spore production -we know burning the bodies is a requirement after all.)

The short version is, that like everything: it depends, and generalizing is tricky. I favor both the "older" calcs in some cases and with certain kinds of las weapons and las-calcs, whereas In other cases I'll favor the "newer" calcs, even if they are lower. And it can't hurt that I can also say that I'm trying to be more conservative about the calcs - I don't want to come off as being some sort of number-wanking maximalist fanboy, after all

[Connor MacLeod]

A long delayed update in my long string of "looking at surgical lasers to judge laser effects based solely on temperature."More generally silly obsession on my part in the past about temperatures and such and generally overcomplicating the matter because, frankly, I didnt bother to understand it (Not seeing the forest for the trees, and all that.) Thank god for places like Atomic Rockets or the Laser Death Ray site. At best this was overcomplicating the issue and ignoring certain crucial factors, at worst I was completely and utterly wrong. Again it can serve a lesson methinks and it reminds me to never assume I know everything (because I don't.)


link

Each wavelength has a somewhat unique effect on dental structures, due to the specific absorption of that laser energy in the tissue. Some lasers are only absorbed by blood and tissue pigments, while others are only absorbed by water as well as hard tissue, like enamel, dentin, and bone.

This is generally true.. the atomic rockets sidearm entry and comments I've seen by Mr Luke Campbell confirm this. What it comes down to in practical terms is that a real laser would have to be "tailored" to a specific target (color, material type, etc.) for maximized effectiveness. What it means is that a truly defining characteristic of lasweapons may be how efficient it is in using the energy - a high end lasweapon (hellgun, noble or Inquisitor's laspistol) might be computerized/automated enough for it to self-adjust to the target's composition, range coloration, and so on, to maximize damage. A run of the mill Guardsmen's lasgun may not be nearly so efficient, but uses brute force to achieve effects at the cost of inefficiency and other limiting factors (more waste heat, fewer shots per power pack, etc.)

Lasers produce light energy that can be absorbed by a target tissue, and this absorption process produces a thermal reaction in that tissue. Depending on the instrument's parameters and the optical properties of the tissue, the temperature will rise and various effects will occur. In general, most non-sporulating bacteria, including anaerobes, are readily deactivated at temperatures of 50 degrees C. The inflammatory soft tissue present in periodontal disease can be removed at 60 degrees C; moreover, hemostasis can also be achieved within the same heat parameters. Soft tissue excisional or incisional surgery is accomplished at 100 degrees C, where vaporization of intra- and extra cellular water causes ablation, or removal of biological tissue. Likewise, the aqueous component of tooth structure and bone also boils at this temperature; thus cavity preparation, calculus removal, and osseous contouring can proceed.

Effet of lasers on tissue, non pulsed. Note the temperature thresholds.. 60 degrees or so is the threhold (or thereabouts 65-70 degrees seems to be where it starts happening) for not killing tissue. Damaging/removing tisuse requires at least 100C. It leads me to think that the ideal balance between damage and excessive energy usage is at least 60C but less than 100C - boiling enough tissue and causing steam to expand in a localized area (100+ C) would not only probably rupture the tissue (steam explosion) but cuase severe internal scalding (third degree or so burn wounds - 70C is about equivalent to the 160-170F threshold for rapid scalding I've found) Cauterization would probably even happen in some form (although more probably coagulation, which can also serve the purpose.)

This is far less efficient than simply blasting the tissue explosively of course (pulse train laser), and to achieve the desired penetration (and not use the lasgun like a flame thrower Luke Campbell suggests) would require fairly penetrating radiation. But we know some lasguns can penetrate water very well.




link

Photothermic interaction


A part of the emitted energy (electromagnetic radiation) turns into heat (thermic energy) that brings about the evaporation of the tissue.
The absorption of the laser radiation causes a quick warming up of the biologic structures. This heating of thetissue can lead to different results depending on the technical features of the laser as well as on the utilized power output.

Basically "heat ray" damage effects as Luke Campbell terms it. The opposite is photomechanical (explosive damage.)

Temperature: 42 - 60 °C
Protein denaturation: the first observable thermic effect is the dissociation of hydrogen bonds in the proteins and in their compounds.


Temperature up to 43- 45 °C

At such temperature cells and tissue can still endure damage but only for a little while: after some time the damage becomes irretrievable and leads to the death of the cells.



Temperature between 50° and 60°C

At such temperature occur coagulation and vacuolization processes, that means that a reduction of enzimatic activities as well as a remarkable denaturation of macromolecules like: proteins, collagene, lipids and haemoglobin..

The denaturation of molecules, and especially of collagene, is the reason for the "structural shrinking" of the molecules and therefore of the tissue.



Temperature: 100°C
At 100° occurs the evaporation of the water contained in the tissues.
At such tissue temperature occurs the formation of many "vacuoles" that tend to expand, due to the transformation of water from liquid into gas.

These "vacuoles" build up in the hottest areas of the tissue under the irradiated surface and because of their remarkable enlargement in size they exert a pressure on the surrounding tissue. Once the critical pressure has been reached, vacuole walls break up and form bigger agglomerates.

If the breaking up of the vacuole walls occurs on the surface, the damp goes out and the surface is slightly cooled.
After the whole water content has evaporated, the tissue will undergo a remarkable thermic increase.


Temperature over 100°C

After the vaporation of the cells, if one proceeds with the action of the laser ray, temperature increases further, up to the point, where carbonization and evaporation of tissues, the last stage of laser-tissue interaction, take place.
All above described effects can occur even at the same time in different parts: depending on the penetration depth into the target-tissue, the resulting thermic effects will be different.

The effects of various tissue temperatures on tissues.. again it reinforces that specific range I mentioned beofre (I tend to think 70-75C would probably be ideal for a heat ray that didn't rely on flash burning. Double digit kj to the heart would probably cook it pretty thoroughly. Or the lungs or brain.. any of which could be fatal I am sure.

Photomechanical Interaction


Photomechanical effects are generated when laser impulses hitting the target tissue are very short and have a high power output, concentraqted on very small surfaces.

The short emission duration of the laser ray, along with the high energy density that is focused on a tiny point, bring about the transformation of the thermic energy of the laser into a mechanical effect, capable of causing the destruction and evaporation of the hit tissue.

In dentistry the Er-YAG laser operates exactly in such way: by a mechanical effect, it ablates the dental hard tissue.

The achieved destruction of the dental tissue depends on the fact that in the treated area, internal pressure goes up until micro-explosions occur, which entail the destruction of the organic constituent and, subsequently, the fusion of the tissue itself.

Photomechanical damage mechanism, or the "blaster" style effects I believe Luke Campbell believes are ideal, and I am hard pressed to disagree now.

Link - google book example

Photothermal interactions include a large group of interaction types resulting from the transformation of absorbed light energy to heat, leading to a local temperature increase. Thermal effects can be induced by either continuous wave (CW) or pulsed laser radiation.
...
Depending on the duration and peak value of the temperature achieved, different effects like coagulation, vaporization, melting or cabonization ma be distinguished.
..
It is essential to emphasize that thermal interactions in tissue are typically governed by rate processes, i.e. not just the temperature plays a role, but the duration for which the tissue is exposed to a particular temperature is also a parameter of major importance.

More on photothermal effects, and goes to show (I think) why its not terribly efficient for heat ray lasers unless its pretty penetrating.

Generally, below the boiling point of water, thermal interactions are dominated by protein denaturation and tissue coagulation, resulting in many cases in cell apoptosis or necrosis.
...
For example, during interstitial hyperthermia, relatively weakly absorbed wavelengths are used, cobmined with long exposure time (minutes), to slowly coagulate or cook a mass of tissue such as a tumor using fiber-optic delivery of laser light.

Effects below boiling point.

Around 100C, the thermal interactions become dominated by evaporation of water and we typically operate in the regime where physical material removal occurs. In this case, the goal is usually to remove or ablate the target tissue while minimizing the damage to the tissue left behind. Some notable exceptions to this paradigm include those applications where, in addition to cutting with the laser, some coagulation is desirable, for instance, when the target tissue is highly vascularized. The amount of collateral thermal damage is largely determined by the amount of heat that can diffuse out of the irradiated tissue prior to the ejection of this mateiral.

Effects at boiling point. A localized, high temperature increase probably would be more explosive than a slow CW laser heat ray, but it probably wouldn't be nearly as explosive as photomechanical/blaster style effects.

The chronicle of ablation with a continuous-wave laser generally follows the following sequence:
1.) Light interaction with tissue (goverened by tissue optical properties).
2.) Conversion of optical tenergy to thermal energy (heat generation)
3.) Tissue temperature rise (heat source and conducton)
4.) Denaturation and dehydration of the tissue (this may affect the thermal and optical properties of the tissue)
5.) Increase of subsurface pressure
6.) Explosion reuslting in the expulsion of heated tissue fragments - this removes energy.
7.) Exposure of cooler subsurface layers to light energy (then going back to 1).
8.) at some point, all the tissue water has been evaporated and carbonization/pyrolysis of tissue will occur.

More heat ray like effects.

During tissue vaporization, the position of the tissue surface, where tissue and air meet, moves deeper into the tissue. The velocity at which the ablation front moves into the tissue is called the ablation velocity. By using a moderate irradiance and measuring surface temperatures with an IR thermal camera, it is possible to document the initial surface heating and explosive ejection of tissue. The onset of ablation occurs above 100C due to subsurface superheating. As hot tissue is rmoved, a cooler layer is exposed to the laser irradiation. The temperature of the exposed lasyer remains at approximately 100C while continued irradiation dehydrates the tissue. The removal of water decreases the local thermal conductivity, reducing heat conduction to the surrounding area. Continued radiation rapidly increases the tissue temperature until it reaches about 350 to 450C; the tissue burns and carbonizes.

One thing to be certain here is that I think "vaporization" despite being mentioned is used interchangably with ablation.. it may refer to the (sort of) explosive removal of tissue as the water content turns to steam. Note the temperatures at which tissue burns/carbonizes. That's important, but I suspect in lasgun wounds the depth of the carbnization is rather thin (a few mm to a few cm tops?) which limits the raw outputs I used to get by this (EG you don't need to have the whole volume turn out that way, nor would it neccesarily.

At, or just above 100C, water vapor is generated volumetrically, the equilibrium is pushed toward the vapor phase, and, for sufficiently high laser fluence rates (irradiances), more vapor is produced than can escape by simple diffusion. The excess vapor is trapped in the tissue layers, forming vacuoles. The superheated vapor contained in the calvuoles will expand quickly, compressing the surrounding, rapidly drying tissues that form the vacuolar walls. As the vacuoles expand, the wall separating the vapor pockets from each other or the tissue surface become thin. The walls rupture as the force of the increasing pressures of expanding vapor overcomes the mechanical strength of the tissue.

The ablation process again, which seems to be constnat (but prolonged) at 100C. A weapon could not/would not be so prolonged, so I expect the explosive effects would be more pronounced (speed is a major component in the violence of an explosion, after all. - its waht defines high or low explosives, for example.)

Based on the very nature of the interaction of laser radiation with tissue, as we have seen, the damage mechanisms may be thermal or mechanical. In brief, mechanical damage is caused by subsurface explosion of heated tissue material (in particular, in cases where the absorption coefficient is relatively small), whereas thermal damage is caused by two sources: 1.) Thermal diffusion (from heated tissue to surrounding cooler tissue); and 2.) direct deposition of heat in layers beyond the point where the energy density was sufficient for ablation ie below threshold. The irony is that reducing the pulse duration will minimize the amount of heat diffusion that can take place before heated material is ejected. However, this same reduction of the duration of the pulse will cause the ablation process to be even more explosive and violent, thus increasing the collateral mechanical damage to the tissue.

More on the "thermal vs Mechanical" effects which again alludes to stuff already mentioned by Luke Campell.

As we have seen, laser ablation appears to be a trade-off between causing thermal damage with long pulses and mechanical damage with short pulses.
..
For laser pulses shorter than the thermal diffusion time, the distribution of thermal energy is determined by the laser light distribution. This situation is known as thermal confinement. If the laser pulse duration is larger than the thermal diffusion time, the thermal energy propogates into the tissue during the laser pulse.
..
A major photomechanical interaction during most tissue ablation events is tissue water vaporization, resulting in explosive removal of tissue structures, which as beeen described as the popcorn effect for CW lasers. Note that in this scheme, the explosiveness of the process may be severe enough to eject liquid or solid tissue fragments. As such, the energy needed to accomplish a certain crater size may be significantly less than expected based on calculations that assume true vaporization of the tissue. This ejection process is driven by the fact that water when converted to steam has a volumetric expansion of approximtely 1620 at 1 atm.

More of the above. The volumetric expansion (the increase in volume it occupies as its density decreases due to being converted from water to steam, I believe) is certainly interesting.

Summery of Photothermal interactions:
Main idea: achieving a certain temperature that leads to the desired thermal effect.
Observations: either coagulation, vaporization, melting, or carbonization.
Typical pulse durations: 1 ms - minutes [note - symbol in link is for microsecond)]
Typical irradiances: 10-10^6 W/cm^2

Irradiance in watt/cm^2 is one reason I started looking at flash burns intensities when looking over this material.

Photomechanical interaction includes mechanisms associated iwth photoablation, explosive vaporization, plasma-induced ablation, and effects of laser-induced acoustic(shock waves). Note that even though we discuss them separately, photothermal and photomechanical events are closely intertwined. Photomechanical mechanisms can be caused by the thermoelastic expansion of tissue due to extremely rapid heating of the target tissue by the pulsed laser light and recoil caused by ejection of ablated material. These photomechanical interactions cause stress waves, which propogate with the speed of sound or faster. If the laser pulse is shorter than the time it takes the stress wave to propogate out of the irradiated tissue volume, large peak stresses can be reached. These stresses may contribute to the ablation mechanism and may inflict damage to adjacent tissue.

Yet more photomechanical stuff.

link - another google book

When the temperature of the tissue has reached its limiting value, namely, the boiling point of its major constituent (water in soft tissue,or minerals in bone), the rate of thermal abduction reaches its maximum, namely the characteristic power density of thermal conduction.
If the radiant power density being converted to heat in the tisuse is lower than the characteristic power density of thermal conduction, the temperature of all points within the tissue will reach equilibrium values above normal body temperature (37C) but below the minimum boiling point of water (100C for fresh water at atmospheric pressure). Conversely, if the absorbed power density is much greater than tha characteristic power density, the temperature of all points in the irradiated volume will rise rapidly to teh boiling point of cytosol, with consequent destruction of cytological and histological architecture by explosively expanding vapor (steam). For histological temperatures at or below 100C, the time needed to carry away significant quantitites of heat is several seconds. If we assume that the temperatures of all point swithin a given mass of tissue rise quickly to 100C because of irradiation at high power density, then the volume occupied by this tissue acts as an isothermal source, (ie , a source at constant temperature), because its temperature cannot rise until all the water is vaporized. From this source, heat will be conducted away to the vascular heat sink in a quasi-steady-state situation.

More on what happens to tissue at boiling point.

...the vaporization of cytosol will be so rapid that the resulting steam becomes superheated because it cannot expand quickly enough to maintain its pressure at atmospheric value. When this occurs, the pressure within the vapour can rise to very high values in very short times (ie microseconds or less), producing a blast, a shock wave of high pressure that propogates spherically outward from the region of absorption.
..

Absorbed radiant power density below 1x10^W/cm^2 does not cause mechanical effects of sufficient intensity to tear soft tissues into fragments containing still-viable tissue, although the acoustic waves resulting from irradiation at histological power densities between 100,000 and 1 million W/cm^2 can cause cell death by rupture of membranes.

Achieving explosive effects in tissue - again note how time matters to create explosive effects - thats why photomechanical (blaster) style effects are so efficient. Also note they not only have to go fast, but for small surface areas effected, again as predicted before by others.

link

A 4 mm central corneal cut was closed with use of a CO2 laser (600 mw, 0.9 mm spot size), with tissue temperatures ranging from 45-70 degrees C and welding time ranging from 1-30 seconds.
...
The optimal results of wound binding by laser welding in the enucleated bovine eyes were achieved with 55-60 degrees C and at a welding time of 12-20 seconds.

repeitition of tissue times and temperatures.. again higher temps mean less time (same stuff as with scald burns and injuries.

html version of a powerpoint article

Surface evaporation:
Mostly photothermal
Raising skin temperature to over 100oC (with CO2)
Subsurface explosive vaporization:
Vapor trapped under tissue and cannot expand, mechanical pressure builds up and causes tissue to eventually explode
Combination photothermal and photomechanical
Raising temperature of RBCs to 125o C with Pulsed Dye Laser
Raising temperature of melanosomes to 112oC
Explosive expansion of superheated fluid:
Tissue water explosively expands from tissue
Mostly photomechanical
Raising skin temperature over 100oC with 2940nm Erbium:YAG

More photomechanical/photothermal stuff.


yet another google book

Thermal effects are based on a temperature increase in the irradiated tissue due to the deposited (absorbed) light energy. This temperature increase leads to either thermal denaturation (coagulation) or to superficial removal (ablation) of tissue. For tissue coagulation, temperatures between 45 and 150C are necessary depending on the exposure time which is typically in the millisecond to second range. Tissue ablation requires temperatures above 100C and cna go as high as several 1000C.

More for thermal effects and the variations on temperatures. I suspect the variance is due to time, volume/area affected, tissue types and other factors. This probably also means that, despite what I did earlier, it cannot be generalized upon.

Mechanical effects due to short pulsed laser irradiation lead to explosive ablation on tissue surfaces with smaller thermal damage zones and higher ablation efficiency compared to purely thermal (evaporative) tissue removal. In cases where the light-absorbing structures are not evenly distributed but are localized withinthe tissue and in transparent media short laser pulses of less than 100 ns can be used to create tissue disruption associated with cavitation and strong acoustic transients.

Photomechanical again.

linky

There are two types of lasers: continuous-wave and pulsed. An example of a pulsed laser is the pulsed holmium:yttrium-aluminum-garnet laser, which, in the free-running mode, has a pulse duration of 250 µs; it has been suggested as another candidate for performing TMLR

250 microseconds, or 2.5e-4 seconds. Again this echoes some of Luke's comments as well.

Upon absorption of laser radiation by tissue water, rapid heating occurs. As energy is spent on vaporization (latent heat), the temperature ranges from 100° to 150°C. After local desiccation of the tissue, the temperature continues to increase to 350° to 450°C, at which point carbonization and ablation (removal) take place, thus exposing new cooler layers.

More temp related tissue effects, including the carbonization.

The laser emits a single burst of energy with a pulse duration that can be varied from 10 to 99 ms

Pulse duration again.

link
This one I can't quote but the relevant chart is on page five. To summarize as follows:
Temperature (in Celsisus)/effect
<45 - Reversible tissue heating
45-60 Changes in cell metabolism and celluar water distribution
~60-100 Coagulation
~70-100 Shrinkage of collagen matrix
>100 Carbonization, vaporization, ablation.

another link

Recently, however, laser technology has cleared some
hurdles. By applying chirped-pulse amplification to solid-state
lasers, Livermore researchers have built systems producing terawatt (1012 W) pulses with ultrashort durationsÑwell under
a picosecond. (Chirped-pulse amplification is described in
some detail in the article on multilayer dielectric gratings in
the September 1995 issue of Science and Technology Review.)
According to theory, subpicosecond durations are far too short
for appreciable electron energy to be transferred to
surrounding material. As a result, less laser energy is absorbed
by the tissue, so material should be able to be removed by
subpicosecond pulses with essentially no collateral damage.

More photomechanical effects I believe. Useful for precision here. I doubt RL lasers would get to picosecond though.. at least for damage-causing purposes (precision matters in medical stuff. You want to hurt the enemy.)

Indeed, this collateral damage has been a real concern with conventional laser-surgery pulsed systems. For example, laser cutting can significantly heat material some distance from the
area being irradiated, causing either desiccation of the material
or, if there is water below the surface, explosive vaporization
resulting in torn tissue

Damage resulting from prior surgical lasers.


Html version of a pdf... other was damaged

The thermal effects, as a result of vibrational relaxation of the excited molecules and of the internal conversion (IC) are, in their turn, of two types [5]:
1) Localized, when a local heating of the biological medium is produced, followed by one of the phenomena: coagulation (when t 60 °C), vaporization (when t 100 °C), carbonization (when t 150 °C) or melting (when t >> 300 °C, for instance, in the case of dental enamel);
2) Delocalised, when the radiation energy «deposited» as heat, is propagating from the place of the radiation-tissue impact: step by step (i.e., by thermal diffusion), by convection or by a radiative process (via infrared radiation) to regions more or less away, explaining thus the «distance effects » of the incident
laser radiations.

More on thermal effects. I believe it means to read as t=a given value... its just that the html from pdf to conversion was bad.. I'd have takne from the PDF if the initial file wasn't damaged.


another link

The thermal response of tissue may be classified into three categories depending on the degree of temperature rise and its history. They are 1) tissue hyperthermia at 43 to 50C (Cell death occurs); 2) tissue coagulation beginning at about 55C (protein denaturation takes place); and 3) tissue vaporization, charring, and ablation at [Less than or equal to sign ] 100C

yes another link

AT a temperature around 60-70C coagulation effect is dominant, and at 100C cell water boils, resulting in cell rupture. At a temperature in the range of 70-100C, the structural integrity of the cell is lost. This process of thermal denaturation leads to coagulation. Laser-induced vaporisation of tissue is followed by formation of pressure waves that can cause mechanical damage in adjacent tissue.
...
While the cells at the surface are vaporized and removed the bulk temperature stays generally below 100C causing coagulation..

Yet more thermal effects. Again 70C or so seems to be the "ideal" for a heat ray affecting an entire volume of tissue (from surface to inside) rather than just flame-throwering the outside.

yet another link

The usual target protein [in laser surgery] is collagen, which has a denaturation threshold temperature of 65C in situ (about 60C in vitro). Elastin, another common vascular protein, has a denaturation threshold of around 110C, just above the vaporization threshhold.

More on temperautres.

this is a link that was redirected from the original PDF, so the html version is used

Extracellular matrix (ECM): this is a fibrous scaffold among which the cells nestle, and which gives tissue most of its stiffness and structure. It is made from collagen and elastin and other glycoproteins and proteoglycans. The ratio of the amount of ECM to number of cells varies widely depending on the type of tissue. Liver and muscle, for instance, are low in ECM, whereas bone, tendon and the retina are largely ECM. Fig. 14 shows images of extracellular matrix from artifically engineered tissue and ex vivo tissue. The collagen in ECM is of interest when considering thermal effects because it breaks down at temperatures well below 100 C. (The chef Heston Blumenthal uses light to soften the collagen in steaks before cooking them, to make them more tender.)

More temp silliness.

37 C is normal body temperature, and for the first 5 C or so of heating few irreversible changes occur.
• At 42.5 C a number of effects, covered with the blanket term hyperthermia, begin. Cell proteins - both membrane and cytoplasmic proteins - start to undergo conformational (shape) changes. They change conformation because the hydrogen bonds keeping them in their native state are broken by the increasingly violent vibrations of the molecule as the temperature increases. When a protein molecule changes shape it can often no longer fulfill its function within the cell. For instance, when enzymes, whose catalytic functions depend crucially on their shape, begin to deform, reaction rates within cells slow down. Even at small increases in temperature some cells will die because of these effects. The rate at which cells necrose (or apoptose) increases with the temperature.
From ∼ 45 C the collagen fibres forming the ECM begin to shrink as the collagen’s tri-helical structure breaks apart. The optical scattering in the tissue increases - it whitens (think of frying chicken breast), then the collagen softens and gelatinises. (Gelatin is just tangled, random coils of collagen.) Tissue starts to coagulate, and blood clots form.
At 100 C the water in the cells and extracellular fluid boils. The huge volume expansion as the water changes phase (vapourises) can lead to tissue being expelled from the skin surface.
• Once all the water has boiled off, the remaining organic material may char (carbonise, blacken). At very high temperatures it will eventually evaporate.

More temp silliness.. basically I think telling us what I've already said. I really went for repetition back then


another link

PHOTOTHERMAL
Photohyperthermia
Photothermolysis
Photocoagulation
Photocarbonisation
Photovaporisation Reversible damage of normal tissue (37-42°C)
Loosening of membranes (odema), tissue welding (45–60°C)
Thermal-dynamic effects, micro-scale overheating
Coagulation, necrosis (60-100°C)
Drying out, vaporization of water, carbonization (100-300°C)
Pyrolysis, vaporization of solid tissue matrix (>300°C)

The terms and temperatures.


link - Google html version of document

Photohyperthermia -37 – 43 °C No irreversible damage of normal tissues
44 – 60 °C Cell membranes damage, enzymes denaturation
Photocoagulation 61 – 100 °C Coagulation, necrosis
Photocarbonisation 101 – 300 °C Drying out, vaporizing of water, tissue carbonization
Photovapoisation > 300 °C Pyrolysis, vaporization of solid tissue matrix

More terms and temps. There seems to be an overlap point between coagulation and carbonization as well, on ewould note.

The photomechanical effect is a secondary effect of the photothermal and photochemical effects. High density laser energy causes tissues to melt to ionized plasma or causes tissues to vaporize into very high temperature gases. It also causes volume expansion of the plasma or the gases, and in turn, causes dielectric breakdowns and local mechanical ruptures in tissues. As the tissues breakdown, they are explosively or ablatively removed.

Photomechanical fun.

Hard tissues usually refer to teeth and bone tissues. Hard tissues consist of solid materials that require much higher temperatures to melt or vaporize than soft tissues that consist mainly of water. Laser photothermal effects are a little different with hard tissues since hard tissue mechanical properties are different. Photothermal effects with hard tissues are comprised of evaporation, explosive tissue removal, plasma-mediated ablation, and physical modification.
Evaporation
When the surface temperature of hard tissues rises to its boiling point, usually over 600 °C, direct tissue evaporation results. Either high output power lasers, such as CO2 lasers, or ultrashort pulse lasers can be used to evaporate hard tissues since very high laser power densities are required to raise hard tissue temperatures to their boiling temperatures.

..
Explosive Tissue Removal
Explosive tissue removal processes happen when hard tissue surface temperatures are much lower than the tissue melting point temperature but higher than 100 °C. Water below the hard tissue surface is rapidly heated and vaporized, but the water vapor gas is confined by the hard tissue surface matrix since the hard tissues are not yet melting. As the water gas pressure below the surface rises rapidly and exceeds the strength of the tissue surface matrix, the hard tissue surface ruptures and is explosively removed.

More photomechanical stuff, vs thermal. The interesting stuff here is with the bone, as it hints at that "variable effects" thing depending on the specific tissues (and their properties.) Note you can "melt" bone.


Another google books entry

The goal of laser surgery is to create a temperature gradient or profile in tissue that will result in coagulation or vaporization of tissue. Coagulation provides hemostasis and, if desires, necrosis of tissue. Vaporization (the convesion of solid and liquid phase tissue components into gaseous phase components) provides the ability to cut, incise, excise, resect, or ablate tissue.
Coagulation and vaporization are two different effects created by the same process: heating of tissue. Coagulation generally occurs when the temperature is elevated from 60C to <100C. Obvious changes occur in the tissue at these temperatures resulting form the thermal denaturation of tissue protein, and include blanching and shrinkage as wellas puckering due to dehydration. When the temperature is elevated near and abov the boiling point of water (100C) vaporization of liquid and solid components occur. A frank defect is left that includes a zone of char (carbon, as a result of the combustion of tissue) surrounded by coagulated tissue. The extent of the area of vaporization, char, and coagulation (as well as a heat affected zone surrounding the coagulation, which can cause edema) is defined by the temperature gradient. Thus, by altering the gradient, the surgical effect can be alterred. There are several variables that determine the gradient. They include the laser parametrs such as power density, duration of explosure, wavelength, and method of delivery of laser energy as well as tissue parameters.

more definitions for "vaporization" and coagulation at least as far as tissues go. I suspect, honestly, that lack of bleeding in some lasguns is probably more due to coagulation now than outrigth cauterization/carbonization, although some of that will doubtless happen also.

Table 3-1 Power density and tissue effects:
Power density:
<100w/cm^2 Dessication, denaturation, warming
>100W/cm^2 Photovaporization, carbonization (Carbon appears as target tissue temperature reaches approximately 150C)
600-2500 W/cm^2 Photovaporization(ablation), minimal carbonization, superficial
hemostasis, target tissue temperatures may reach 300C
>10,000w/cm^2 Ultarapid photovaporization, thermal incision
>50,000w/cm^2 incision of tissue, approximately same rate of cutting as for scalpel
>10^6Wcm^2 Plasma formation, acousting shock waves, tissue destruction by mechanical disruption rather than thermal denaturation.

Interesting in that its more power density (surface area effects rather than volume ones.) The one problem with me using this for anything is that "watts" are not joules, and this doenst tell me about timeframes. Still it's useful and telling.

another google book

Assuming a body temperature of 37C, no measurable effects are observed for the next 5C above this. The first mechanism by which tissue is thermally affected can be attributed to conformational changes of molecules. These effects, accompnaied by bond destruction and membrane alterations, are summarized in teh single term hyperthermia ranging from approximately 42-50C. If such a hyperthermia lasts for several minutes, a significant percentage of the tissue will already undergo necrosis as described below by Arrehenius' equation. Beyond 50C, measurable reduction in enzyme activity is observed, resulting in reduced energy transfer within the cell and immobility of the cell. Furthermore, certain repair mechanisms of the cell ar disabled. Thereby the fraction of surviving cells is further reduced.
At 60C, denaturation of proteins and collagen occurs which leads to coagulation of tissue and necrosis of cells. The corresponding macroscopic response is visible paling of the tissue. Several treatment techniques such as laser-induced interstitial thermotherapy (LITT) aim at temperatures just above 60C. At evne higher temperatures (>80C), the membrane permeability is drastically increased, thereby destroying the otherwise maintained equilibrium of chemical concentrations.
At 100C, water molecules contained in most tissues start to vaporize. The large vaporization heat of water (2253 kj/kg) is advantageous, since the vapor generated carries away excess heat and helps to prevent any further increase in the temperature of adjacent tissue. Due to the large increase in volume during this phase transition, gas bubbles are formed inducing mechanical ruptures nad thermal decomposition of tissue fragments.
Only if all water molecules have been vaporized, and laser exposure is still continuing,d oes the increase in temperature proceed. At temperatures exceeding 100C, carbonization takes place which is observable by the blackening of adjacent tissue and the escape of smoke. To avoid carbonization, the tissue is usually cooled with either water or gas. Finally, beyond 300C, melting can occur, depending on the target material.

More temperature stuff.

Table 3.6 Themral effects of laser radiation:
37C - Normal
45C - Hyperthermia
50C - Reduciton in enzyme activity, cell immobility
60C - Denaturation of proteins and collagen, coagulation
80C - Permeabilization of membranes
100C - Vaporization, thermal decomposition (ablation)
>100C - Carbonization
>300C - melting

Yet more temperature stuff. note that this time we have a "melting" temp - it would seem that carbonization/cauterization and melting could be the same thing, at least for certain kinds of tissues.

It is illustrated in Fig 3.21 how the critical temperature and the corresponding temporal duration relate to each other if irreversible damage is meant to occur. The curve is derived from several empirical observations. In the example selected in Fig 3.21, a temperature of 60C lasting for at least 6s will lead to irreversible damage.

ACcording ot the chart, 70C at 1s will be irreversible damage, a fraction of a sec at 80C - which seems to confirm my opinion of the "ideal" heat ray tissue killing temps.

Areas in which the temperature reaches values higher than 60C are coagulated, and irradiated tissue cells become necrotic. Areas with maximum temperatures less than 60C are treated hyperthermically only, and the probability of cells staying alive depends on the duration and temporal evolution of the temperature obtained.

...
Carbonization, vaporization, and coagulation certainly are irreverisble processes, because they induce irrepairable damage.[/quote]

More temp and tissue effects.

PDF file - download only
similar material can be found here

Laser and Tissue - Thermal Processes
- Hyperthermia: meaning a moderate rise in temperature of several ºC,
corresponding to temperatures of 41º to 44º for some tens of minutes and resulting in cell death due to changes in enzymatic processes. This is a difficult procedure to control and so it is little used in practice.

- Coagulation: refers to an irreversible necrosis without immediate tissue
destruction. The temperature reached (50º to 100º C) for around a second, produces desiccation, blanching, and a shrinking of the tissues by denaturation of proteins and collagen.

- Volatilization: means a loss of material. The various constituents of tissue disappear in smoke at above 100º C, in a relatively short time of around one tenth of a second. At the edges of the volatilization zone there is a region of coagulation necrosis: there is a gradual transition between the volatilization and healthy zones. The haeomstatic effect is due to this region of coagulation necrosis. If the volatilized zone has a large area of some millimeters in diameter, it is possible to destroy tumors bigger than those treated by a simple coagulation. If the volatilized region is narrow, a cutting effect is then obtained.

"Volatiization" means vaporization or ablation basically.. might be useful for lensman calcs though

Laser and Tissue - Mechanical -
Producing a Shock Wave
n Mechanical effects can result from either the
creation of a plasma, an explosive vaporization, or
the phenomenon of cavitation, each of which is
associated with the production of a shock wave.
n Creating a Plasma
– With nano- or pico-second pulsed Nd:YAG lasers, a very
high intensity of luminous flux over a small area (between
1010 and 1012 W/cm2) ionizes atoms and creates a
plasma. At the boundary of the ionized region, there is a
very high pressure gradient which causes the
propagation of a shock wave. It is the expansion of this
shock wave which causes the destructive effect.

When the exposure time of the laser is lower than the
characteristic time of thermal diffusion in the tissue, it
produces a thermal containment, with an accumulation of
heat without diffusion and an explosive vaporization of the
target.

Photomechanical effects once again.


Google books link

The most widespread surgical applications of lasers in medicine employ the phenomenon of photocoagulation. In this process, proteins, enzymes and other critical biological molecules in tissue are heated to temperatures well above 50C with a resultant denaturation occuring almost immediately. This type of thermal energy of tissue at a very high rate, a high temperature may result, which produces a more rapid rise in temperature and a more rapid lesion formation, untila tissue temperature of 100C is exceeded. AT a temperature exceeding 100C, photovaporization results. Thus, to obtain optimum photocoagulation, the laser beam delivery rate must achieve a temperature in the coagulation zone of 50-100C. At relatively low temperatures near 45-50C it takes several seconds to achieve photocoagulation, wheras at higher temperatures approaching 100C photocoagulation can occur within fractions of a second.

..

Longer exposure durations are utilized to coagulate (or ablate) larger tissue volumes by making use of heat conduction during exposure. When this technique is employed, the exposure rate must be reduced so as not to exceed the critical temperature of 100C

Photocoagulation... again this is my new idea for lasgun "cauteirzation"


yet more google book results

Ablation is primarily the result of heating and evaporation of tissue water. The abrupt change in thermal behavior at the water-steam phase transition must be taken into account in the energy balance. The ratio of specific heat ot latent heat of vaporization of water (2500 j/cm^3 at 37C) is relatively large.

..

When pulsed lasers are used in tissue ablation, other mechanisms, such as plasma formation and photochemical processes, also play a role. The pulse duration must be less than the thermal relaxation time of the tissue to confine laser-generated heat to a specific region.

Ablation.

Page 23.2.7.2

Approximately 5 to 6 times the amount of heat required to raise water of 37C to 100C and an additional 2.25x10^3J/CM^3 is required to vaporize the water. Thus in concept, the delivery of energy larger than the amount necessary to bring a small volume of blood to a cirtical temperature for vaporization could simply raise a much larger volume to the critical temperature without producing bubbles in the blood.

More temp stuff.

Page 23.3.3

Exposure times longer than a few ms imply that substantial heat conduction occurs from the "hot" structures, such as epidermis and blood vessel, to the "colder" structures, such as dermal collagen which has the lowest absorption coefficient of the skin constituents.)

..

The iron heater effect refers to a hot epidermis that heats the underlying dermis through heat conduction, as if the epidermis were an iron heater.

..

Results for a 100C surface temperature are presented in figure 23.17. In this figure an "epidermis" of 100C temperature heats an equally thick layer of dermis (to a depth of the same thickness as the epidermis, about .06mm) to a temperature of 70C within .023 s.

More surface/tissue temps.

25.2.2
The pulse duration of the laser controls a number of events. First, if the pulse duration is short enough then there will be little diffusion of the thermalized optical energy during the pulse.

..

Niot only does one wish to confine the thermalized optical energy to the site of absorption, but one also wishes to confine the induced pressure to the site of absorption. This requirement is based upon the recognition that short-pulse duration laser ablation of tissue is driven by a thermal explosion: the tissue temperature and pressure both rapidly rise during the laser pulse and tissue removal results because of the high pressures induced. One manifestation of the explosive nature of short-pulse-duration laser ablation is that plume velocities greater than the speed of sound in air have been measured by several investigators. Pressure waves travel at the speed of sound. Thus, the pulse duration should be shorter than the time required for a pressure wave to traverse an optical penetration depth.

..

The speed of sound in tissue is approximately equal to the speed of sound in water, ie approximately 1500 m/s....
..

If a constant energy pulse is shortened to the point where the incident irradiance is approximatley 10^8 W/cm^2, then plasma formation is likely.

Photomechanical stuff again.

25.2.3.3
In general, if the irradiance exceeds approximately 10^8-10^10 w/cm^2 in the presence of local impurities, then a plasma will be initiated in the thermionic process. Irradiances greater than 10^11 W/cm^2 will generally initiate a plasma in the absence of impurities via a multiphoton absorption process.

Plasma formation (for ablation/photomechanical processes).

(chapter 25.2.3.4)
For wavelengths at which the absorption coefficient is not large and therefore one can have thermal confinement of the thermalized optical energy with a relatively long pulse (e.g. greater than a few milliseconds), power may be the more descriptive parameter. That is, if the pulse duration is long compared with the time that it takes to eject tissue from the ablation site, then tissue may exit from the beam path during the pulse and the incident radiation can penetrate more deeply into the tissue than would be predicted form the absorption coefficient.

Yet more photomechanical stuff... again millisecond seems to be the hard boundary (if one exists) where thermal and mechanical effects diverge, although in truth there probably is more overlap than anything (eg a few milliseconds is where most mechanical efects start getting eclipsed by thermal. It doesn't mean that the explosive/mechanical effects suddenly vanish.)


Miore google books hooray

At distances less than 1mm, temperature is near 100C that it could be occured carbonization.

..

In the other side, bubble information, vaporization, and carbonization affect on quality of images near and upper than 100C...

Temperature stuff again.



More google books references

The effect produced on body tissue by elevated temperatures depends on the maximum temperature reached. Most cells will survive temperatures up to about 45C, but 60C cell death begins to occur. At higher temperatures, between about 70C and 80C, the collagen in cells is denatured and tissue contraction takes place. Water is driven out of the cells at 100C. AT 250C carbonization (charring) occurs, whereas at 350C the tissue is vaporized.

Yet more temp stuff.. including the charring/carbonization stuff.

another google book, but with electrosurgery

The extremely high current density delivered by the arc rapidly superheats the cellular water to temperatures greater than 6000C. explosive cellular vaporization ensues seocndary to the production of highly disruptive pressures (steam occupies 6 times th evolume of liquid water) and acoustic forces.

Bit of an outlier, but its not really lasers I think. Along with arc flash analysis electricity/lightning invariably seems to involve higher temps for harming tissues.

As the tissue is slowly heated to temperatures above 50C and maintained, irreversible cellular damage is initiated by deconfiguration of regulatory proteins followed by the denaturation of cellular proteins (white coagulation) Further heating to 100C leads to complete evaporation of cellular water (Dessication), hemostatsis secondary to the contraction of blood vessels and the surrounding tissues, and conversion of collagens to glucouse that has an adhesive effect between the tissue and electrode. Temperatures above 200C cause carbonization and charring. The prudent application of monopolar electrosurgery to tsisue is continuously moderated by monitoring for the terminal evanescence of steam formation and tissue whitening; tissue charring and smoke are indicative of overzealous coagulation.

Until the tissue reaches a temperature of 100C and is completely dessicated, the rise in tissue temperature is directly proportional to the tissue resistance (Degree of dessication), time of current flow, and the square of the current density.

More coagulation and itssue temp stuff, albeit not a laser again.

Although the higher voltage sparks are larger and create broad areas of charring (to >500C) and tissue desturction, current flow is limited to the superficial tissue layers due to rapid dessication and the build up of tissue reisstance.

Charring.


another google book..

Skin will burn at 45C afte rseveral minutes, but at 60C only a few seconds is required.

Time and temperature again.

another pd file

Minimally invasive thermal therapy has been explored as a means of treating small solid tumours.3,4 It involves
heating the target tissue to temperatures between 55oC and 95oC for several minutes which results in coagulative
necrosis. This is differentiated from hyperthermia, which involves lower temperature (40oC to 45oC) and longer,
multiple applications (several tens of minutes) and has been used in conjunction with muti-fractionated radiation or
chemotherapy.

Tissue temps.

In addition, if tissue temperatures exceed 100°C, tissue charring may occur,
which should be avoide

tissue temps. Note some charring can occur close to or at 100C


yes, another google book

Thermal effects mainly.

Depending on the local increase in temperature, four effects can be produced: coagulation, vaporization, carbonization, and melting. Coagulation requires a local temperature in excess of 60C and is associated iwth necrosis. At temperatures above 100C, the vaporization of water induces thermomechanical effects that are responsible for thermal tissue ablation. Carbonization, i.e. the release of carbon, occurs when the tissue temperature exceeds 150C. AT even higher temperatures, tissue melts as a result of the denaturation of tissue protiens (for example, collagen). The latter effect is used in laser tissue welding, in which proteineous or dye-enhanced solder may also be used. Thermal interactions are typically induced with optical power densities of 10-10^6 W/cm^2 and pulse durations of 10^-6 - 10s

Tissue effects (from thermal at least.)

Photoablation refers to the photochemical composition of cellular and extracellular components by direct breaking of molecular bonds by UV photons.

..

Power densities are relatively high, in the range of 10^7-10^10 W/cm^2, and pulse durations range form 10 to 100 ns.

More ablation, and power densities stuff. Photoablation and photomechanical seem to be, for surgical purposes, similar.

At high optical power densities of 10^11-10^13 W/cm^2, which are typically delivered over relatively short times (10^-13 - 10^-10 s), the electrons in the tissue are subject to an electric field that induces forces higher than the atomic attractive forces, thus causing breakdown and the formation of ionized plasma. On the one hand, this plasma of free electrons strongly absorbs optical radiation leading directly to ablation (plasma-induced ablation). On the other hand, at even higher pulse energies, shockw aves and cavitation (formation of microscopic gas bubbles) may also take place leading ot photodisruption.

More wattages and densities. Again blaster-like effects.

[white_rabbit]

This all seems like bullshit to me, you're just assuming the highest yields possible and waving your hands at everything else.

Also, I note you've changed your opinion on one or more things as time has passed.

Ample evidence in my mind that you just change your mind when presented with new information.

Pathetic!

[Connor MacLeod]

Oh drat you figured me out! I'll be undone if my critics find out about this!

[Darth Hoth]

Um, why the backslapping? I would have thought this thread was in fact a tacit admission that some critics of your earlier work did in fact have a point of sorts, at least on some issues.

"Connor now writes down some of his figures" does not equal "Everyone who ever criticised Connor is crazy," after all.

Not that I am accusing you of dishonesty, mind. But it seems you also would agree that your earlier numbers for lasgun firepower were not in fact always so conservative as many people have liked to claim. Although rather because of lack of knowledge than any deliberate obfuscation.

[Connor MacLeod]

No, my numbers weren't as conservative as some people would like, but that is almost beside the point. The point basically is there was a whole nother angle to such weapons that I failed to take account of, and it has a rather BIG impact on conclusions when you do stuff like that. That doesn't mean that "big numbers are suddenly wrong" - it means "it depends on how those numbers are used" - a heat ray that still melts or boils or vaporizes still needs to inject that amount of energy to do the damage it does, but that isn't the only way to do it. Nor is it the most efficient or effective way, but depending on capabilities and desired roles (and how the weapons work) a designer may opt for that.

[white_rabbit]

What the fuck are you talking about Hoth?

Where is this "backslapping" you are burbling about, because it sure as shit isn't in my posts.

[Lord Relvenous]

What the fuck are you talking about Hoth?

Where is this "backslapping" you are burbling about, because it sure as shit isn't in my posts.

Your first post wasn't sarcastic?

[Connor MacLeod]

He always jokes at me like that. It's part of his charm.

[Connor MacLeod]

Since I already answered this one I got bored and decided to dump the last two documents I'd had pertaining to lasweapons. The first one is yet another (revised) intro to lasweapons. This was my "previous" revision and marked the beginning of the "change of heart" so to speak, although I think I've toned that down as well to "its all good".


I swear it seems every year I'm making a resolution to revisit my lasgun methodology. This would be like the third time. First time was silly since I assumed eveything was vaporized (ah, ignorance). Secondly then I fixated on multi-megajoule calcs alone and cauterization. Not neccesarily all bad, but it did ignore some vital possibilities and evidence. Third time is the charm they say.

It's not so much I'm abandoning "vaporization" or "cauterization" per se, either. I'm just diversifying - taking a broader approach to the analysis (or, at least trying too.) Kilojoule range calcs aren't neccesarily inconsistent or unreasonable either. It all depends on setting and application (explained further below.)

Basically we have a number of different examples of lasgun operation. We have sustained beams, we have pulsed bolts. We have cases of mostly thermal effects, where lasguns melt, vaporize, burn, char, sear and cauterize, and we have cases where they messily blow something apart. We also have cases where they just poke holes through a target or slice it apart. We could say lasguns are inconsistent. We could say they make no sense. In a way, the ykinda don't. We can also say they're highly versatile weapons, and can produce a multitude of effects depending on design, modifications, settings, and loadout. We know lasguns come in many different varieties. We know they can be single shot, burst, or fully automatic. We know they can utilize different kinds of powerpacks. We know they can be highly customized or modified even in-field. We know they can have multiple charge settings. We even know from some sources that they can have multiple firing settings even. There is tremendous room for all the variation displayed with a lasgun, and it can fit within existing theories and be made sense of, which is the important part.

In a large part, it comes down to efficiency, and tradeoffs. A given lasgun powerpack will have a certain amount of energy available to it. Several things can apparently affect this. One is "charge" setting - as in low power, high power (or max power, if that is different setting) and mid power shots. An example of this is the Triplex lasgun. Another possibility (mentioned in sources like Ian Watson novels and The Munitorum manual) is that lasgun settings can alter power outputs - a sustained beam taking up more power than single shots, for example.

The tradeoffs inherent in those two factors are obvious - more energy in a shot means fewer shots available. So it makes sense that you might want to minimize the energy expenditure as much as possible without compromising effectiveness. One such way is a pulsed beam with mostly mechanical damage effects - an "explosive" burst. Such a setting would be highly effective while conserving "per shot" power - more shots.

So then why would they need sustained beam weapons? In some caes it could be to blend thermal plus mechanical. Or maybe they need to rely more on thermal damage (reducing something to ash, melting it, etc.) or the "explosive" setting may not do anything. You might think of it as being the energy weapon equivalent of incendiary or thermobaric weapons instead of HE/Fragmentation. Alternately it could be that (at least for some rifles) the two different settings represent two distinct kinds of lasgun. Its certainly not unreasonable, given the aformentioned endless variation.


Explosive/mechanical damage:

Aside from observed examples, the best evidence for this damage mechanism comes from the description in the third edition rules:

tHe Inquisitor novel also specifies mechanical damage as does the uplifting primer, but not as a primary mechniam, whereas the third edition rules specify it almost as certainly a primary mechnaism. Second editon rules (from the Battle Manual before it, and reiterated in the Munitorum manual) suggest that they have an effect "similar to a bullet or small shell" which does imply mechanical damage, but is not guaranteed.

Thermal damage:

This largely comes from the uplifting primer and novels and the Inquisitor game. The uplifting primer describes "boiling" and "cauterization" and "burning" The Inquisitor novel and uplifting primer actually describe it as a "dual effect" of shock and burning. This largely amounts to what we might call a steam explosion - the tissues heated so rapidly that pockets of steam build up inside the flesh, rupturing it.

Thermal effects, while canonical, cannot be said to be terribly efficient as a damage mechanism compared to mechanical damage - its far more energy intensive which carries drawbacks (reduced number of shots and potentially increased cooling issues which may decrease rate of fire or firing endurance.)

If we must include thermal effects, several possibilities occur:

1) - difference in lasgun design/operation. Some lasguns may be more efficient than others for various reasons - different use of materials, different kinds of components (EG focusing elements). There may even be tradeoffs in reliability (more sophisitcated lasguns are more efficient, but also comparatively more fragile.) More efficient lasguns may be of the type that have considerably higher rates of fire and greater ammo capacities from the same powerpack (EG the Munitorum manual and Gaunt's Ghosts depictions typically, as opposed to the Dark Heresy/Inquisitor/Imperial Armour depictions)

2) - tradeoff in capabilities. Higher energy bolts/beams arguably have greater range than lower energy bolts (hotshots in hellguns and long las, for example) Its possible that some armor may necessitate greater energy inputs to penetrate defenses (there is an argument for body armor, particularily that involving ceramite, having superconductive properties. Carbon is also known to be a component of body armor, a material known for having good thermal properties. Support for this is that the aforementioned hellguns and lasguns, as well as max-power lasgun shots, are known to be employed to penetrate armor, including carapace and Marine power armor (Ghosts novels, Guard novels, etc.)

3) - versatility. The possibility exists that a "thermal" damage mode is more effective against some targets than others. As noted in 2.) armor may be one such possibility, but the properties of some organic enemies (Orks or Tyranids perhaps) may require thermal effects to counter certain abilities (rapid healing, for example). It may also allow for incendariy properties (akin to incendiary ammo, flamethrowers, or thermobaric weapons) which may be effective agianst certain targets (IE detonationg ammunition or fuel) or psychological/terror effects.

Possible thermal damage mechanisms may be severe (second/third/fourth degree) burns or scalding (boiling water content in the body), coagulation of tissue due to thermal effects, general cooking of internal organs or fatal increases in internal body temp (most animals have a certain temperature maximum that is fatal) It may even be that also be simply that some lasguns have such plentiful power supplies that they can afford for thermal and mechanical effects simultaneously (steam explosions as well as burns and internal cooking.)

Such performance would arguably be enhanced by some capability of the lasgun to "scatter" shots over a larger area (to facilitate the creation of widespread burns, sort of a shotgun or flamethrower like effect, or just the ability of some machine guns to spread fire over a wide area. The latter would also add a "suppressive fire/area target" capability to lasguns, which has also been depicted.) The fact that at least some lasguns may not be strictly photonic lasers may also help explain this ability, as lasguns have been known to exhibit exceptional penetration through organic tissue (penetrating multiple targets such as in the Ghosts and some of the Guard novels) and significant penetration underwater without loss of cohesion (Gaunt's Ghosts and Eye of Terror), in addition to the abilit yto penetrate through bricks while retaining lethality (Battlezone Cityfight) - such penetration facilitates more efficient internal heating.

It is known that the bodies of some creatures (EG orks) must be burned to prevent the spread of spores or contamination (Chaos creatures or mutants may be under similar requirements, depending on the nature/type of such creature.) Lasguns have been known to have "incinerating" effects or the ability to set things on fire (Blood angels novels, Shira Calpurnia novels, the Ghosts novels and the Necromunda novel Junktion) and it is possible the thermal mode is designed to act as an impromptu flamethrower to allow partial incineration of key components (eg head, heart, lungs, spine, etc.) of crippled or killed enemy. Such modes may also be required for "lethal" hits as well.

Rate of fire:

Lasguns have demonstrated highly variable rates of fire, depending on your source. The 2nd edition Wargear guide specifies a "machine gun like" hail of blasts.

Gaunt's Ghosts varies, but latter books tend to suggest incredibly rapid rates of fire - 20-40 shots a second or more.

The uplifting primer and 13th Legion imply rather slow rates of fire - the former giving the lasgun a 220 RPM rate of fire while the novel mentions a lasgun with a ROF of 5 shots/second.

A number of sources (The Ghosts novels, the Cain novels, etc) specify that power packs discharge rapidly, in a matter of seconds, implying tremendously high rates of fire.

the Gray Knights novel has "hundreds" of guardsmen unleahsing "thousands" of shots each second. Soul Drinkers, the novel Ice Guard, and a few others suggest 10-15 shots a second easily.

Added to this are "continuous beam" references, like from Gaunt's Ghosts, Inquisitiion War, and Gray Knights.

An explanation for this may lie with the notion that rates of fire are variable. There are precedents for this with real life guns, such as the Browning Automatic Rifle which had two rates of fire. Some modern rifles have a "burst" mode ROF which is alot higher than its cyclic as well. We could also infer that some modes are "burst" (a pulsed laser) and others are sustained. The insane (dozens of shots a second) could come from rapid finger pulling coupled with the burst fire mode (often described as "semi automatic" in Inquisitor and Dark Heresy.) The difference in rate of fire may lie in differecnes between "pulsed" (explosive) shots and "sustained" (beam/thermal) shots as well. The latter often involves many shorter duration pulses and coudl also involve a lower overlal energy content "per shot", which allows higher rates of fire, whereas sustained would increase the energy output but also the duration per "shot", which consequently reduces rate of fire.

Two primary sources argue for this method. The first is the munitorum manual, which hints that single shot and "full auto"



Alternately its possibe that there may be cooling, controllability, or power usage issues. "Semi" automatic may bea a more limited for of "rapid fire" compared to a "full auto" mode, again hearkening back to the BAr's tow different fire rates. This would also fit with the difference in power usage hinted at in the Munitorum manual differeing between single shot and "full auto" - single shot providing "more shots" (even though, technicaly, the shots should remain teh same between the two.) This statement would make sense in context of a "sustained" vs "pulsed" shot.

The other example primarily is 13th Legion, which features the "fractrix pattern assault laser". Earlier in the book it is stated that the weapon has a rate of fire of five shots per second. Later, a single trigger pull unleashes half a dozen bolts, and later over a period of several seconds "dozens" of bolts are unleashed. This is an apparent inconsistency, but may be made sense of in light that the former implied a "sustained" output (the 5 shots/sec could be sustained for 15 seconds out of two powerpacks) whereas the latter two often seem to involve "pulsed" shots.

As an aside, the novel "Crimson Tears" features a triplex pattern lasgun which is best known as a "variable setting" weapon - it features a multiple rate of fire as well depending on source (the triplex originally showed up in the Inquisitor RPG, but has since popped up in other cases.)

A low ROF like 220 RPM is slow compared to an assault rifle, but with a "sustained" beam setting it could make perfect sense . We know many lasgun beams persist long enough to be observed. Average human reactions can vary between 1/3 to 1/5th of a second, and that would allow 3-5 shots per second on a "sustained" beam mode. This is not neccesarily super-slow either - the aforementioned BAR had this rate of fire, and many shotguns do as well (and a sustained beam could emulate that effect reasonably well - allowing "raking" type shots.)

Laser, particle beam, or both?

White Rabbit has long held that lasguns are a personnel version of a lance, which according to Andy Chambers is a hybrid laser/particle weapon. Traditional "definition" of las weapons has them as photonic/massless beams in nature, although exceptions occur.

2nd edition mentions "laser shells". The latter Ghosts novels are particularily infamous for a "weird" definition of lasguns suggesting they aren't lightspeed weapons (people seeing and/or dodging laser bolts.)

Lasguns sometimes do have bizarre properties that would be hard to explain with lasers. Many lasguns can fire underwater quite well without scattering. Particle beams would not *neccesairly* fire underwater better, but they have incredible penetration.

Another bizarre property is that lasguns can sometimes make a small entry wound or minimal external damage - inflicting massive damage without explosive effects of any kind. The sort of penetration you might expect from a particle beam weapon.

The visible nature is another obvious one pointing at a hybrid laser/particle or a particle beam nature.y

One possibility (again something suggests by White Rabbit) is that the actual nature may vary according to design and location - some lasguns are photonic, some are particle beam, some may be both.

It is possible that a few lasguns may be "projectile" or "pseudo-projectile" like the abnett novels suggest, but its not a theory I particularily like. In such a case I'd tend to liken them to a variant weapon like a needler or Eldar mandiblasters in effect - another "hybrid" type weapon rather than being an acrtual particle weapon. Perhaps the bolts are comprised of bits of matter or particles that release photonic energy on impact (one interpretation of blasters)

Range and accuracy.

A lasgun beam regarldess of nature is designed to be a highly accuratecompared to projectile weapons. A massless beam (or near-c particle beam, such as it may be) propogates near-instantly over great distances and sufferes zero (or nearly zero) drop in gravity, and suffering zero effects from atmosphere or wind. Lasguns are also often indicated to have little or no recoil. Any recoil if it exists (such as in the ghosts novel) would likely come from other means (explosive interactions inside the gun, ejection of coolant gases, etc.) High rates of fire (especially continuous beams) would also contribute to accuracy, and with the vast ammo supply they can afford extensive barrages. This means that at equal ranges, lasguns would have an advantage over conventional slugthrowers, and quite probably could shoot much farther.

The closest analogue I can think of is flecthette or saboted weapons - extremely high velocity and small/low mass projectiles (like the Steyr ACR). High velocity over a short distance can allow nearly flat trajectory and high accuracy (300-400 meters).

Ranges of a kilometer or more (several kilometers) occur in multiple sources (The Ghosts novels mainly, but many other sources indicate similar such as Space Wolf novels, assault on black reach, inferred from various FFG material sources, etc.) The longest ranges exist for the Long-las by sniper "Mad" Larkin in the Ghosts novels of 4 klicks, although the implication this is merely luck rather than a consistent range.


Combat roles:

Lasguns are the basic firearm of the Guard, but the exact "parallel" to modern weapons is not specified. In truth, given the variable types of regiments, lasguns do ont seem to fit into one particular role - lasguns can duplicate semi-automatic/bolt action rifles, assualt rifles (with intermediate cartridges), or something like the M14 (called a "battle rifle" although I've heard some argue that isn't an appropriate term.) Hotshots would seem to exhibit properites akin to a antimaterial rifle. On the far end of the scale you have "heavy" lasguns (mentioned recently in "Blood Pact" but also hinted at in other sources, such as the "auto lasers" from an anthonlogy short story or the lascannons/multilasers in "Lords of the Night" or the space wolves novels.)

Several novels (13th Legion and Honour Guard, as well as other Ghosts novels) make mention of "assault las", which may be a reference to a close combat lasgun (like an assault rifle). There are also carbines (equivlaent to rifle carbines like the M4 or a submachine gun) and of course the "long-las" sniper rifle. Like modern rifles they can also vary between single shot, full auto, or "burst" modes (2-3 round bursts, possibly like "semi-auto" settings.)

We may also see variations in the Ghosts novels. Prior to VErghast, the ghosts primarily were light infantry/scouts/skirmishers with an emphasis on long range marksmanship. Fewer and more powerful shots seemed to be more common place. Post Verghast, and again Post "Hist Last Command" (Belladon regiments) we see more diversity popping up - the VErghastites are more "urban warfare" troops and are equipped with differing lasguns - a high rate of fire with more shots per pack and lower output (more optimized for mechanical effects) would be consistent with that kind of weapon. The Belladon troopers were also light infantry/scouts as I recall, but they may have had weapons of both kinds (or another kind entirely.) being more akin to "main line" troopers perhaps.

[Connor MacLeod]

Part 2 is something new, and might provide a different (if potentially more conservative) approach to lasguns than what I'd taken before. I'm looking at the power sources and the data ther eis there. There's suprisingly alot in recent times - mainly the FFG material has expanded this but a few sources here and there made mention as well. I've touched on batteries a very little bit in a few early ones (eg the 600 hour flashlight from Gaunt's Ghosts) but not very deeply. I don't know if this can be any more "accuratE" than the measurement of effects, but it can provide a useful way to compare/contrast the two and hopefully establish a happier, more consistent range.

That said there is potential for some crazyness (EG the Inferno entry for lascannons, isotropic fuel rods, and other similar power sources.) and I may even do some exotic speculation (promethium fuelled lasguns, while not existing, would fit in perfectly well with the canon, as would fuel cell or non-rechargable batteries.) It also turns out that the "liquid metal batteries" often mentioned in the fluff may not be total fiction, although they don't quite mesh up with what we know either.




Solar rechargeer (wargear, munitorum manual, IA3)

Powerpacks recharge from heat and light (munitorum manual, core rules 3rd, etc.)

recharge by sticking in fire (Traitor General, Ice Guard, Munitorum Manual, Sabbat World Crusades book)

Solar recharge (Death World)

Autolasers (Abnett short story, gyro stabilized), portable lascannon (Lord of the Night), heavy lasgun (blood Pact).

Backpack power source (hellguns Conquest of armagedon, Siege of Vraks pt 1, IG 3rd - Fornux Lix firedrakes) Hotshot packs (2nd, 5th edition, siege of vraks)

Related: Power generators plugged into for infinite firepower (cities of Death, Planetstrike)


Hellguns

Hellguns became the main weapon of stormtroopers in later 40k games and in a great many novels. They ar baiscally more sophisitcated lasguns, more capable than the infantry version but also requiring more maintenance, leaving them to only "higher end" forces like storm troopers. The actual benefits of the Hellgun have varied form source to source. Some, like the Munitorum manual, suggest hellguns output the same energy "per shot" as a lasgun but fire a higher power, higher intensity beam (basically focusing the energy on a smaller area and delivering it more rapidly.) as well as being better at penetrating armor. This, I suspect is largely based on game mechanic interpretation of the stats (hellguns are the same strength as lasguns, but have an AP value). Other sources, like Dark Heresy and IA5, make it explicit that Hellguns pack more energy per shot (DH in particular specifies hellguns consume 4x more energy than lasguns.) It is not neccesary to assume that one sources is neccesarily "more right" than the other - like with Lasguns, there may be many many variations and types of hellguns, and variations on capability. Some overlap with the "high end" of lasguns may be expected (It must also be noted the Munitorum manual has some inconsistencies with the hellpistol entry, suggesting by number of shots and effects it is considerably more powerful than a laspistol.)

Some sources, like IA5, credit hotshot lasguns and hellguns being the same thing. This isn't true of all sources, but we could consider that hellguns probably can use hotshot packs, and thus be a more "high end" sort of hellgun (an insanely powerful one, to be sure.)

Calcs for hellguns exist, but not as many as lasguns. And they do vary somewhat. And with the Munitorum manual and Dark Heresy hellgun refs, it is failry easy to figure out hellgun firepower from lasguns (or vice versa) anyhow.

Hotshot lasers

Hotshot packs are the high end capability of the lasgun. They provide the highest power, most energetic burst, but also the fewest shots. They basically trade versatility (the ability to easily recharge them, and number of shots) for raw power. They may also possibly influence range, since a more powerful shot ought to be lethal out for a much greater distance and lose more energy. Hotshot packs seem to combine high energy with high intensity/power, making them the "most" explosive. Some sources (conquest of Armageddon, effects against Astartes) also suggest they have an armor pirecing/"anti-materiel" role as well.

Originally Hotshot packs were backpack sources for lasguns, given to the Storm Troopers (see below). Over time they evolved into "hotshot" clip packs as well, and the well knonw single use "hotshot" packs the Ghosts were famous for (and picked up by Dark HEresy). The latter in particular had traits different from "earlier" hotshots - single use (as opposed to 20 shots established in the uplifting primer and other works) but could also be recharged in much the same way regular powerpacks could (EG in a Fire, which is mentione din the Ghosts novel "Traitor General"

While in theory all lasguns can use a hotshot pack, it is implied that the ones storm troopers use (nd sniper rifles) might be specially designed to take advnatage of them, although at the cost of requiring better maintenance, so it may be considered that at least some "hotshot" lasguns are just the high end of the hellgun/sniper rifle range (indead IA5, siege of Vraks, suggests just that.)

As a further aside regarding Dark Heresy, DH introduces "overcharged" power packs, which are an intermediate between hotshot and regular power packs (more power = fewer shots), and showed up in novels like the first Grey Knights novel.

Calcs for hotshot packs exist, although most come from the Ghosts novels and involve the "single use" packs. The Munitorum manual says hotshots are more powerufl than Hellguns, although it also indicates hellguns are the same energy output as regular lasguns. Further complication is that the effects of the hotshot packs in those books most often match up or are exceeded by *other* feats by non-hotshot packs (EG exploding heads), although this may be because of "over-penetration" no source ever makes it clear that hotshot packs expend ALL their energy against a single target. It may also simply be a difference in timeframe, design, or model of lasgun. Another possibility is that hotshot packs also benefit from "variable charge", even though this isn't indicated to be the case with either the "multi shot" hotshots or the ghosts "single use" variety.

Another possibility, and a more likely one is that with like regular lasgun packs there are a variety of makes and ratings for hotshot packs. Some could vary number of shots, the power/intensity of the shot, or the energy, or the other factors. Some hotshots might deliver less energy "per shot" but do so far more rapidly and to a smaller area (and therefore explosively), while others rely on raw energy to achieve their greater effects.

Fires and solar recharging.

Two established means of recharging a lasgun powerpack away from some sort of approved power generator or recharging station. The first is solar recharging. This started from second edition largely, but popped in via other references such as the munitorum manual (which basically lifted it from 1st/2nd editionf luff), and the Imperial armour books (which make a habit of lifting up and modifying earlier material.) It isn't actually clear how solar recharging of lasguns or the powerpack works. Some implication is that the capability is built into the weapon itself, but we never see any power cells. It may be a separate device, or a "flip out" feature on the lasgun (or at least certian kinds of lasguns), or it may be both. It may be not all lsaguns share this feature, since it may detract from other capabilities (rate of fire, for example, or ease of use.)

Solar recharging is not neccesarily efficient or quick, and not always reliable (since alot of variables can infleunce it) but it is a good "last ditch" effort to keep your offensive capability. The possible energy output is low, which suggests it may only be practical with certain settings (IE low energy "explosive" settings.) or designs/modifications.

The other capability is built into the power packs themselves - that you can expose the cells to heat or light and then recharge them. The most extreme method of this is throwing the powerpacks into the fire (mentioned in many sources and novels: Sabbat Worlds crusade book, the ghosts novels, the novel Ice Guard, the uplifting primer Dark Heresy, etc.) although this reduces the effectiveness of the pack - reducing ammo capacity and making it less reliable. The method has the advantage of being faster than solar recharging, and allowing more energy to be stored in the pack although in the long term its probably not the ideal solution given the adverse degradation the pack seems to suffer. (although there are probably ways around this - setting them in the fire would be the most efficient but you could probably rig other ways nearly as so without putting them in said fire.)

At least one instance of power packs recharging (or attempting recharge) by absorbing sunlight pops up in Death World, although it is implied to be far less effective even than either method above.

It must also be noted that some have argued in the past that the above capabilities are proof that the lasgun is a more limited or less effective weapon than other instances indicate. This logic fails to take into account that the above capabilities represent "emergency" measures - they are a relfection on the versatility of the lasgun rather than a limit on its capability. The rationale behind the "variable output" nature of the lasgun and the tradeoffs in "high" vs "low" power apply here - the ability to recharge the lasgun by sunlight or fire is meant to allow the weapon and its user to retain effectiveness under any possible condition. Such always entails tradeoffs of one kind or another, and it does not mean this is standard practice (which is in fact using a power generator of some kind to recharge them, as indicated in sources like the Munitorum manual, and the fact that many instances of guardsmen combat tend to feature them employing fresh packs rather than recharging what they do have on the fly unless no other alternative presents itself. This is rather even a key point of the 5th Ghosts novel, in fact.)


Backpack power sources and generators

Backpack power sources hark back to 2nd edition with the introduciton of Storm Troopers. They were like normal guardsmen but had a hotshot laser power pack plugged into their regular lasgun Around 3rd or 4th edition, hotshots were still there but we also got hellguns popping into use as storm trooper weapons. Hellguns were also backpack powered weapons and in some sources (siege of vraks part 1) were treated as interchnagable with hotshots (while others, like Dark Heresy and Gaunt's Ghosts, treat them as separate types.) 5th Edition resurrected the "hotshot" lasgun as the standard Storm trooper weapon, but they're all backpack power sources (various novels like the Armageddon novels, the Imperial armour sources, etc.)


Generators showed up in 4th edition's Cities of Death as a strategy. Basically the idea was that plugging your lasgun into some power source (either a prefab one, a portable one, or something inside the city) youc ould get ivrtually infinite shots. In a way it makes sense, and it

[Lord Relvenous]

He always jokes at me like that. It's part of his charm.

Oh good. I was afraid my sarcasm meter was broken.

[Cykeisme]

An excellent read.

Not properly relevant, I'd like to say that the 4th ed name was so much better. "Hellgun" sounds kickass for a high-powered lasgun, way better than "hotshot lasgun".

[Connor MacLeod]

An excellent read.

Not properly relevant, I'd like to say that the 4th ed name was so much better. "Hellgun" sounds kickass for a high-powered lasgun, way better than "hotshot lasgun".

Hellgun is generally just ot reference any weapon that requires actual maintenance for its improved performance rather than swapping out components (like a lasgun does.) Lasguns and long-las can use hotshots (or be modified for higher outputs) but have tradeoffs (longer charge time between shots, shorter ranges, increased barrel wear). I'd actually say that while the knowledge investment is higher for hellguns, in the long run they're actually more efficient and effective than a lasgun as far as materials and resources go, but as las weapons still can have ammo and manufacturing/reliability advantages over bolters.

Hot shots are power sources (clip and backpack types) and can be used for either weapon. They just would work better for hellguns because some hellguns are designed to cope with/handle increased power outputs (although some hellguns aren't much better than a lasgun as far as raw power output go - the difference in firepower there comes from the way the energy is used and the rate of fire, which also affects the penetration.)

[Connor MacLeod]

I decided for simplicity's sake to go back and "re do " som ecalcs. I'll probably redo them at a later point as I intend to revisit the Rennie and Ghosts novels I've covered as wlel sa the Cain and others (like 13th Legion) I simply wanted to sort of do an "illustrative example" - well alot of examples of both the old ones and a few "new" ones.

Bear in mind that this is just an alternate "take" on my other calcs - the old ones are not neccesarily "wrong", as a "heat ray" laser will behave differently than a "blaster" type,a nd alot of it ultimately depends on how the weapon works if nothing else. Admittedly some of the calcs (EG the ones involving total vaporization of a specific volume of body) probably are wrong.. with a few exceptions (EG eldar head vaping from the 2nd edition Codex Eldar, or as mentioned in Black Tide)

Also bear in mind that if people use these calcs, note whether it is explosive or heat ray.. or a hybrid. If it is obviously burning shit but the head (or body) is intact, its a heat ray. If its blowing apart, vaporizing, or otherwise blasting off, its at least partly explosive, if not outright blaster. THERE IS A DIFFERENCE, and the tow cannot be easily compared. Hell I think punching 30 or 1-2 cm diameter, non cauterized holes in the human body is more effective than flamethrowering the entire thing (double digit kw vs single digit MW) for example.

lasgun analysis thread (old)

A las-blast felled the armsman beside Semper. The captain grabbed the man as he fell, intending to drag him into the bay, but then found himself staring into the excavated crater of the man's skull, where the las-shot had blown half his head away.

alot easier than when I used to do it. Single digit to double digit KJ could handle it from an efficiently-designed lasweapon (something akin to shotgun, full powered rifle, or at most a .50 BMG). Actual energy might be greater (depends on efficiency, presence or absence of burns and other thermal effects, etc.) but effects wise it's there. I'd guess on at least some third or fourth degree burning, which might double/triple the energy ouptut (but may also reflect a corresponding decrease in "how efficient" it is, especially if there is a speed factor in "flash burns" - something I'm still not totally certain about.)

Skulane's head exploded. He dropped like a sack of vegetables onto the ground...

..

Skulane had been hit from behind by a las-blast to the head

Lasbolt explodes a head again. Whether it was from a pistol or rifle we don't know. Again single to double digit KJ can cover this quite easily.

Seargent Grell was right behind with a dozen men that he had roused out of their panic with oathing taunts. They stood around the lip of the culvert and fired their lasguns down at the twitching skeleton, in a few moments, the sculptural, metallic form of the beast was reduced to shrapnel and slag.

This is, as a rule one of the few calcs I did that remains unchanged. I earlier assumed something akin to a 1 tonne mass of iron being melted in a few seconds (or on one powerpack) which was around 90-100 MJ per pack IIRC, and megajoule range weapons. Is this valid? It might still be, although I'm not sure how convinced I am at MJ range powerpacks being standard. If it was still the same I'd assume either a.) It's a specialty pack (overcharge or hot shot), b.) they used multiple power packs.. although this would only affect the calc by 1/4-1/6 depending on carrying capacity, and it would probably be far less. It also could be they have more shots per pack (hundreds rather than dozens) but that won't affect "per shot" greatly in this case unless they're spitting out dozens of shots a second.

The big thing to remember is that it's not a precise calc.. I'm just doing estimates, so it could be far less than what I figure... It could be only a few hundred kg of iron (hollow bones, it might not precisely conform to dimensions of a humanoid figure like I assumed, etc.)

I'd still assume we're talking double digit KG at least though - man sized mass or thereabouts in context. Even at 20 kg mass (which seems a bit unlikely for something taller and stronge rthan a normal man) we're looking at 20 MJ to melt (not including inefficiencies) so we'd look at 1-2 MJ per powerpack at LEAST (and that still assumes all shots used, etc.) More probably from a few seconds wer'e talking a few dozen shots tops, and we'd get triple digit KW sustained outputs (minimum) from lasweapons.

What I'd probably do is figure it means single or double digit MJ for lasgun powerpacks (which fits roughly with other evidence I've gotten around to looking at better, esp in light of the new take on this shit) with a slight possibility of higher (but in the sense of the Death STar calcs for number of ships or firepower is "reasonable")

Note I still think this shows its quite possible for lasgun outputs to still show at least single digit MW outputs, but it would probably be a maximum power "heat ray" setting.. rarely used because of the power draw it enforces and the lack of explosive effect.

First and Only analysis

A final, powerful las-blast, close range and full-power, took its head off.

Max power shot takes off Space Marine head.. I'd say that its at least several times greater, both because its max power, and because a Space Marine's head is bigger and tougher than a normal humans (both the bone and tissue is tougher, and its larger/more massive.) Probably at least double digit kj to do it (Space Marines have taken stubber or autofire to the head without having skull explode or dying, IIRC.. although the only one ATM I can recall is one of the Space Wolf novels.) 2-4x a normal human head simply for possible mass/volume differences alone.

The wall behind him exploded in a firestorm of light and vaporising bricks. Two fierce blue beams of las fire punched into the room and sliced the man into three distinct sections before he could move.

Alot of it depends on the mechanism. AS atomic rockets and laser death ray mention, it is possible (if you space the shots out in a raking volley) to cut through a person with lasfire in single or double digit kjs (explosive effects, again.) I'd still guess this is happening in a fraction of a second, however, which would suggest a fairly high ROF weapon (double/triple digit kw ROF perhaps). not to mention its overpenetrating like hell.

There's also the apparent lack of bleeding from before. I'd guess at least 3rd/4th degree burns on both halves of the body.. 60-240 kj maybe depending on exact severity (although again this may assume a rather inefficient weapon so it should be treated as an order of magnitude rather than precise figure.)

Two las-shots slammed it sideways. Another tight pair broke it open along the rib cage, venting an incandescent halo fo bright psychic energy. A fifth shot to the head dropped the thing like it had been struck in the ear with a sledghammer.

Colm Corbec, the laspistol in his hand, stalked across the deck of the Glass Bay and stood looking down at the charred and smouldering shape on the floor, a shape that had self-ignited and was spilling vaporous green energies as it ate itself up.

4 lashots to what looks to be blast open torso, at least partly. Again with explosive effects (like headshotting) single digits could cover this easily. The main interesting bit is the "charred/smouldering" bit and the self ignition. Assuming that is from the lasweapon and not the warp effects, that might suggest (if the torso is burning)

His armoured torso pulverised by Zogat's marksmanship, Brochuss toppled into the flecked ica sand of the valley floor...

Hard to calc despite being maximum power.. assuming a single burst, we might figure "pulverizing" is equal to 4th/5th degree, which "flays tissue to the bone". Over a torso area of say 30x30 cm we're talking 360 kj.
This wouldn't be inconsistent with severe burning + a full-auto barrage of fist/head sized shots punching holes through the torso, especially considering the armor (double/triple digit KJ)

Shoudl be accurate to within an Order of magnitude. We dont know how many shots (aside from probably not more than a second, and probably less than that, since the minute any bolt would hit the body would react.. a fraction of a second is not impossible nor unreasonable) We might figure it taking around 1/4 of a second but less than a few seconds, which suggests triple digit kw to several megawatts worth of sustained firepower at maximum setting.

Fulke, Mktea, and Tanhak ran the line. From the back of Fulke's machine, Logris excelled and scored four kills. Mktea's gunner Laymon made one of his own before the upper part of his head was scythed off by a las-shot at the mouth. Tanhak and Grummed made six, maybe seven, good kills before a shorrt-range missile endied their lives and their glory.

Las bolt hits the mouth, "detonates" inside, and blows out the back of the skull. Not uncommon in the ghosts novels. Single digit kj quite probably, probably not more than a few kj since the head is still mostly intact. It might also suggest a highly penetrative bolt (The weapon being designed to deliver its energy forward rather than into the surrounding tissue, much like the lasweapons known for just drilling holes throught he target rather than exploding it.)

The laser burst punched through the top of the bandit's bowl-helmet, presneted as it was by his head-down appraoch. The shot probably passed down through his skull, his neck, and his torso, following the line of his spinal column, Merrt thought, as the figure dropped stone dead in a crumpled pile.

Las bolt penetration the "long way". Alot of the effect depends on how the weapon works, but from head to torso is a good 50-100 cm or so of body. 5-10 kj at least should cover it (not unlike the Battle Laser Luke Campbell conjured up. I'd guess its at least as good, maybe twice that (which itself is 5-10 kj depending on how you interpret his quotes.)

Again this scene (plus the "firing in water" scenes) show extreme penetration of lasfire.. at least for Ghost lasguns.

"Its head was huge, twice the size of a human'

Ork head. not really a lascalc but useful to note simply because some of my weapon calcs involve Ork skulls. Which like Marine heads are bigger and tougher, which makes blowing them apart rather more impressive.

Page 177

"A soldier of chaos, cut down and presumed dead in the ditch, had crawled forward, and now loomed over the inner fence above the scrabbling Volpone. His chest had been blasted open, and blood and tissue dribbled from exposed ribs.

We don't quite know what weapon did this that I recall, but it's possible a lasgun did from what I recall (it was the Ghosts and Volpone against Chaos troops in ghostmaker defending a farmhouse. THey only had lasguns as I recall ) double to triple digit kj at least to blow out torso not quite grenade level because his torso is still partly intact (unliek bolters) but pretty nasty still. not much severe burning either if he's still bleeding out.. third degree or less (20-50 j per sq cm maybe which would seat the calc firmly in the 20-50 kj or so range within an OoM) We also don't know how many shots.

Men were still coming off the ramp-end above, falling on those Ghosts now coming up from below. A boot had hit him. The man it belonged to was inverted in the water behind him, panicking, dying. Caffran kicked away, trying to rise and not breathe in to ease his emptied, screaming lungs. He saw men explode into the grey, dreamy world from above, fighting the water as they hit and sank. But that at least told him the surface was only a few metres away.

The man who had kicked him on his way down had become entangled with another by the slings of their lasguns. One of them fired his lasgun in desperation, twice, three times. The water boiled around each slicing minnow of orange light. Caffran's ears throbbed as they heard the fizzing reportt of the underwater shots. One fo the las rounds punctured a drifting corpse nearby; another punctured through the leg of a desperate swimmer next to Caffran. Blood fogged the water.

One I did before. This probably doesn't change much in this case, although I'd suspect a hundred kj or so as a "blasteR" might achieve the same, playing around with the laser death ray calculator. I'd treat the boiling effect as proof of subsidary effects.

The other difference is diameter of beam effected. Some source hint strongly at finger-wide (sveral cm) effects on tissue, but we know in others (like the latter ghosts novels) it could be like half a cm. That can affect the calcs a bit (but still within an OoM if everything else stayed the same) so it is worth noting. triple digit kj to possible single digit MJ per shot is my take from this, and I would also probably guess it coudl be maximum power settings.


ghostmaker analysis

Also cutting the strap away (or most of it)

He wondered if he had been shot in the head, if his thoughts and motions were simply a nervous reaction carrying him forward past the point of death, his brain cooked backwards out of the exploded cup of his skull.

Mkoll imagining he'd been hit. Suggests explosive and thermal effects, which is corroborated by a few sources (inquisitor RPG, FFG stuff, etc.) single to double digit kj depending on effects or efficiency.

When a man has been shot by an energy weapon the wound will cauterise so little bleeding will occur, damage is caused internally by the energy bolt heating up and boiling the insides. The energy dissipates, causing massive trauma to the internals and severe internal bleeding.

The cauterisation of the entry wound causes problems in treating injuries, as the wound needs to be reopened to get to the affected area. Proper medical attention is required for this.

Effects of energy weapons in general. This could refer to lasers to plasma weapons of any stripe, so its more general and may only reflect a particualr (and not very efficient) kind of heat ray. but it is still valid. I'd take it as proof of "steam explosion" effects.

Hawke fired a hail of las-bolts, ripping the man's chest to bloody ruin and blasting clear the wall-mounted grille behind him.

A series of shots "ripping the chest" to ruin. Figure this is somewhere along the "chest pulverization" scene above from First and Only.

"But you won't be around to see it," snarled Eshara plucking the pistol from Leonid's hand and pulling the trigger. Naicin's head exploded, showering the platform with stinking yellow fluid and scraps of rubbery tentacled flesh.

Its not exactly a "head" per se, but more a head-volume of wormlike things.. but I dont think (density wise and effects wise) that would matter much for a laspistol. Single digit kj can easily cover it.


Bolter firepower thread

I grin to myself, swinging the laser so that it is pointing at the Colonel. One squeeze of the trigger and a storm of las-bolts will tear him into little pieces.

single shot is about 5-6 shots. I'd again figure we're talking "head pulverization/ripping" scene at least from above, possibly grenade level damage like a bolter (hundreds of kj to close to a mj maybe)

I pull off my helmet and look at it, still a bit dazed from the hit. There's a charred gouge just where my right ear would be, almost burnt through. I poke at it with my finger and I'm shocked when my fingertip passes straight through. The las-bolt had been within the thickness of a piece of parchment from actually getting through!"

One of those "finger burning" bits I talked about. Assuming carbon fibre (one marerial used in flak hlemets) and a ~1 cm thickness of helmet.. it could be double even triple digit kj easily for a hole nearly finger-thick I'd guess (not easy to us the claculator for this part )

Loron glances back and smiles, but when he steps out into the main corridor his head explodes, splashing blood across Lorii who's right next to him.

She gives a strangled scream, the droplets of blood on her face so dark against her alabaster skin, her searing blue eyes looking like they'll pop out of their sockets. I grab her and pull her back as more las-bolts slam into the wall nearby

We aren't quite sure what weapon it is, but most sources imply it was either an auto or lasweapon (these are PDF troops after all) so we have yet another lasgun headshotting. Single digit to double digit kj.. probably mor towards single digit because of the blood and stuff.

There were alreaddy four Steelheads guarding the compound, three more were in Spyglass tower and two at the base of the trail. Neither side would back down and nobody could say who drew first. One badly gut-shot steelhead managed to drag himself almost to Wilferra's gates before he died and the other, bleeding, staggered up the trail as his gangmates ran down to meet him. They fired thunderous heavybore autogun bursts after the Firebrand who'd survived the initial exchange but by then he was a disappearing shadow. The other Cawdor was sprawled on the ground with half his head gone and his chest and belly las-burned almost to ash.

One of those "rare" calcs that probably doesnt change. Cremation of a torso is quite significantly in the megajoules range, but as noted before we don't quite know what the weapon is (other than its a las weapon of some kind) - rather unliekly to be a lascannon (none ver shown and they tend to be rare since they're "anti tank" - they usually explode people anyhow) but it might be a Goliath sized lasgun (which would be more like an Astartes weapon than a normal persons weapon).

Jaq aimed his ormolu-inlaid laspistol and squeezed. Hot light leapt out from the damascened chromium steel nozzle in a dazzling silver thread. He drew the sliver of light across that limb of the hydra as if slicing cheese. He sliced and resliced. Several portions writhed. Gobbets semeed ot wink in and out of eixstence. Though chopped every which way, the whole tentacle squirmed towards where they stood as if still joined togehter, glued by some adhesive force from outside the normal universe.

Cutting beam. Not calcable as such, not leastways because its a psychic creature.

Carnelian rounded on Moma Parsheen, laughing. And still laughing, he plucked a laspistol from his belt and shot her through one of her blind eyes ,boiling her brain.

Either a head explosion or boiling the brain. I'm still leaning towards the latter. single digit KJ one way, triple digit kj the other. It might be double digit (midway point) if only partial boiling happened, which could still be lethal.

The Lieutenant snapped a lasgun loose from a thigh-holster on his plasteel cuisse. Silver runes embossed the barrel. After adjusting setting and focus deftly with his power glove, he handed the weapon to Lex to do the honours.

..

A searing needle of coherent light lanced from the gun.

Resin cracked.

Resin burst

Slime sprayed.

Steam billowed, assaulting nostrtils with a sour vinegary whiff.

Probably not canon anymore, but I don't care I still like it Space marines using lasweapons.

Already bursts of laser energy from her other pistol had melted the leering eyes and features of the other two Flowers-
...

Two of its targets were already dead on their feet. The other two might still have some residual life in their scorch-blasted skulls.

I think I did melting calcs for this before.. but a simpler one is of course burning. Assuming 50-100 j per sq cm.. 20-40 kj at least.. probably several time sthat (since it snot one facing alone getting scorched here)

The remaining Zoican bastard switched to full auto and swung wild. His withering close-range shots punched right through a flak board wall partition and blew the guts and thighs out of Machinesmith Vidor, who had been waiting to spring out from behind it.

Again figure this is not much different from the other "chest blowing" calcs. But it is nice to have a degree of consistency in that regard.

Fire walloped back at them and Corbec marvelled at the way the las-rounds kissed and followed the stone walls. Trooper Fanck dropped, his chest gone. Trooper Manik was hit in the groin and his screams echoed around them.

..

An enemy round took off his and at the wrist and Corbec scooped up the autocannon and fired it himself. Genx, his stump instantly cauterised by hte las-fire, got up without comment and began to feed his colonel's weapon.

Another lasbolt punching a hole in the chest. Although in terms of "gone" I'm guessing there's just a bigass hole, since he's not falling to pieces. Figure a head sized hole (double digit kj) could cause that easily.

Other calc is lasround cauterizing and blowing off hand. single digit kj at least, but probably double digit for cauterization (severe flash burns)

Lesp fought with the struggling Feygor, clamping wet dressings around the scorched and melted flesh of his neck and trying to clear an airway.

"His trachea is fused! Feth! Help me hold him down!"

Bragg fired a last burst or two and then dropped from the stub-nest and ran to Feygor and the slender medic. It took all of his gargantuan strength to hold Feygor down as Lesp worked. The las-hit had cauterised the wound, so there was precious little blood, but the heat had melted the larynx and the windpipe into a gristly knot and Feygor was suffocating.

...

Lesp threw the small, plastic-handled scalpel away in disgust and pulled out his long, silver Tanith knife. He stuck it into Feygor's throat under the blackened mass of the scorched wound and opened a slot in the windpipe big enough to feed a chest-tube down.

This one at least is simpler now. A neck sized area (15 cm or so) and 50-100 j per square cm at least (but less than flaying) probably double digit kj.

Calcs like this and others (like the face melting from Harlequin) show that lasguns can vary between exploding and cooking, for whatever reasons or logic (or lack of logic.)

Three Zoican soldiers in full battledress charged up onto the cageway, blasting at him. Gaunt lost his footing and fell, the las-shots screaming over his head. The shots blew apart the torso of the Volpone leaping in behind him and threw his corpse back and outwards so it fell away down the slope of the hull.

Lasgunb arrage of unknown size blasts apart torso of Armored volpone (rpobbly a storm trooper).. so its probably taking alot of abuse to do that. Still at least triple digit kj.. not complete blowing apart since he still has at least something of an intact corpse.

[quote="Necropolis, page 297"
Beside him, Vinya, one of the loom-girls, rebounded off the wall as a brace of las-shots caught her in the belly.

...

The wound itself had self-cauterised in charred, knotty lumps, but the damage had shredded her insides, and she was bleeding out rapidly.[/quote]

I'll assume some level of flaying damage across the belly area 50-400 j per square cm. In this cae I'm thinking its another indication of how penetrative las "particles" are compared to RL lasers.. they go deeper befor doing this damage, with perhaps the surface burns indicative of only initial interactions Assuming 10-15 cm area we're tlaking 100-200 sq cm which could be as low as a few kj per shot, to 40 kj per shot or so/

The flickering of the daylight was being caused by bright las-roudns passing over us, almost invisible against the hard glare of the sky. Then a shot stung by against the bricks and I saw it clearly. A dart of seething fire, tinged red, the size of a man's middle finger, so bright it hurt my eyes, so fast it was barely there.

One of those "finger sized" bolts. Also this is one of those cases where "seeing" the bolt this distinctly makes me think "Abnett has given the ghosts SW blasters"

Then Mktag rose from his prone position like he had been jerked up from behind by his webbing. He twisted and fell over. For a moment, I didn't understand what was happening. It seemed as if Mktag was just behaving stupidly, mucking around, kicking with his legs.

But Mktag had been shot. Right there in front of me. He fell at my feet, his heels drumming the ground, his hands spasming. A tiny plume of smoke spiraled up from the little black hole a las-round had made in his forehead. There was no blood. The shot had cauterised the entry wound and it didn't have enough power to exit his skull. Its heat and force had been expended getting into his cranium and incinerating his brain.

It was quite simply the most awful thing I have ever seen. His body thrashing, trying to live, the brain extinguished. I think if there had been more blood, more obvious physical damage, I could have coped better.

But it was just such a tiny hole.

I used to think it meant cremating... but I was nver completely happy with that because I'm rpetty sure the steam explosion would blow the brain out. Partial cremation maybe, but that's all. Severe burning seems more liekly, which is more towards triple digit kj (like brain boiling) assuming 3rd degree scalding (100-150 kj per kg) we're taling 150-200 kj.. boiling of course is around twice that. If we go with flash burning? Assume 50-100 j per square cm as my "typical".. figur between 30-80 kj for the bolt, depending on severeity of burns and surface area burnt and size of brain.. double to maybe triple digit kj in other words, from an attack closer to the "heat ray" than blaster variety. Remember that not all lasgun attackls behave the same !

The shortt duration high energy [lasgun] beam produces such a rapid temperature change on the target's surface that it vapourises in a small explosion.

"Tarok slumped down behind the rock.

...


As the stones pattered to the ground, a Deathlight flashed the stunted bushes itno flame. Tarok sprang up and fired at the Brannath who had just given away his position. The man fell forward out of the bushes with a fist-wide, smoking hole punched through his body from front to back. Strange, thought Tarok, that there is no blood.

That thought almost cost him his life. He almost failed to notice the shadow sliding over the rocks behind and right of him. The rock glowed and began to melt as he dived away from the beam of the Deathlight. The Brannath was not quick enough with his second shot.

Then, on all sides of him, the air was shot through with the deadly bright rods of soldier-lightning.

...

They were watching through their magic, he knew - the same magic that made the Deathlight spit its soldier-lightning.

An old calc. I think double digit kj could easily cover the effects, but depending on how its done it could be triple digit. It's going to involve at least some "series of pulses" though, simply to drill through like that, but probably not too many. May be indicative of a lasgunon "full auto" all the shots hitting roughly the same point.

Asusming burns, 30-60 kj would cover it for 3rd degree I think too.

It [the lasgun] fires an explosive energy blast with a similar effect to a bullet or small shell.

Within an order of magnitude, I'd guess (assuming a blaster rather than heat ray weapon, shich is consistent iwth many 2nd and 3rd edition depictions of the laswepaons) the lasgun has the same energy of the bullet. single or double digit kj per shot. Depends on kind of bullet and damage mechanism of course.

The bolt impacted. It tunnelled and exploded. Flesh and bone or a vital organ erupted. It was ever this roudy way. By contrast, laspistols were silent in operation. If the aim was inaccurate, the scalpel-blade of energy soon dispersed. Whener a las-pulse met its target: such lacerating flare-up, such a scream of agony, if the victum still had the breath and lungs and heart to scream. Perhaps ten of the pilgrams had fled. A score more lay dead or dying, almost all thanks to the laspistols."

Chest blowing scene. clearly expplosive. Not blowing torso entirely apart.. but taking lungs and heart does suggest roughly a head sized wound area. Double digit kj should easily cover it, but it could be a few hundred kj. Definitely less than grenade/bolter level damage though.
Assuming burns happen? maybe 20-40 kj per shot.

As he watched, two incandescent bolts of las-fire, each shaped like an elongated spearhead the length of an adult human forearm, squealed overhead.

..

There was a bloody hole the size of a bottle top through his thigh. Mulch worms and flies were already invading [/quote]

bolts have not only length but shape.. again more like SW blasters than acutal lasbeams. It also shows that roughly multi-cm diameter I talked about. A few kj should cover this thorugh a thigh though.. hell with overpenetration. if its bleeding a bit burning can't be too severe.

To my right, Topasz screams. The sound echoes shrilly off the walls. There's the sound of a lasblast and parts of bloody matter spatter across my face and arm as she blows her own brains out.

Another head exploding bit. single digit kj.

One of them, a young man in a tattered suit, had begun moaning and feebly clawing at an open laser burn on his chest. Sergeant Fillonova had taken out her laspistol and was adjusting the power setting.

"give me a moment and I'll close that up for you." Sergeant Fillonova gave Verina a steel-eyed smile and shot the traitor. His chest should have exploded; superheated flesh bursting form the opened wound. However, the slash simply sizzled in the low power beam and the young man writhed in agony.

"Sorry," claled the sergeant, "but you've got to keep still. Wriggle around like that and I'll have your eye out." She fired agian and this time cut a line down the cultist's face, across his left eye, and burned a deep gash in his cheek.

Laspistol settings, and adjusted to be sustained beam and a heat ray. Implies a steam explosion rather than pulse train, but

A lasbolt struck him msquare in the chest.
Uriel staggered, but did not fall, the eagle at the centre of his breastplate running molten.

assuming cermaite, and 2-3mm depth melting across oh 15x15 cm area we're talking hundreds of kj easily. I may do the calc more accuratley some other time.

Calliden came out of his mad, erotic trance. He plunged his hand inside his black tunic, noticing for the first time that it was wet through. Out came the laspistol. Calliden was unused to wielding weapons. It took him a moment or two to wrap his fist around the handgrip, release the safety, aim, and press the firing stud.

Steam bubbled all along the length of the laser beam as it hissed through the water. But it failed to reach Aegelica. Instead, it struck a fish, nearly a yard long, which at that moment had glided between them. The fish exploded as the water in its body turned to steam. Fragments of flesh, skin, and bone drifted to the sea bed.

I'm not gonna bother doing this, since I'm already covering the novel at the same time, except to say "its probably kj range, and there's Chaos involved so it may not be accurate." Its another useful example of lasweapons working underwater though so it parallels Ghostmaker rather nicely as far as intention (They arne't surprised the las weapon is firing underwater. If it wouldn't intend to work you'd think they wouldnt have used it.)

Page 400

Ragnar rolled and snatched a lasrifle from the hands of a guard. He brought it to bear on the stranger and pulled the trigger. Lacking anything to gain purchase on, and forced to follow the arc pre­scribed by gravity, the assassin, for once, made an easy target. Not even his reflexes were swift enough to avoid coherent light, and Ragnar hit him. The beam burned cloth and seared flesh, charring it black. Somehow the assassin managed to keep his arm in the way all the way down, and as soon as he hit the ground, he came straight at Ragnar, despite the sizzle of fat and muscle.

severe burns across an arm area.. double digit maybe triple digit kJ depending on arm size and severeity of the burn. Its a short duration shot (no more than a few seconds) or it may be a single sustained beam shot.

She shook her head in disbelief and prodded her finger into the cauterised hole in the man's temple. The wound was clean and crisp, as though the las-shot had carefully parted each molecule of tissue as it had passed through.

..

As Macha withdrew her finger from the man's head...

Single digit kj easily. One of those "drilling thoruhg" quotes I talked about.


[quote="Crucible of War, page 122]
Erhlsen was kneeling, tracking it with the barrel of his lasgun, leisurely, as if he was at a recreational target shoot. I threw myself flat, just as he squeezed the trigger and the thing's head exploded.

IG with lasgun takes down Tyranid gargoyle with headshot. Much like with Orks and humans, I suspect this to be many times more impressive than normal people ('nids are easily 200-300 kilos even for the lesser forms, which means they're at least a good 3-4x heavir than humans at LEAST.) coupled with their toughened chitin and tough hides and the difference in mass we can talk double digit kj easily, if not tirple digit kj.

Page 163

He rose in time to see one of the raiders flopping over on his back, a hole through the chest.

...

The reamining raider turned in time to meet a streaking las-round face on. His head blew apart in a cloud of blood and metal, and his body dropped.

single digit kj maybe for hole in chest, as well as for head exploding. although blowing apart helmet will add to it.

They had, for a second, clean kil-shots on the fallen Maggs.

However, Mach Bonin had reached the carved stone cover of hte stairway. Turning, face set like an angel bringing solemn notice of death, he emptied half of his last power clip in a flurry of shots that blazed across the echoing chamber.

The shots struck- and chopped into- the three troopers like hacking axe blows. One of the enemy troopers was hit in the knee by a shot that severed his leg. Before his toppling body could fall, he had been sliced through the torso twice, and the shoulder, and the neck. The second pitched over as two shots entered his back above the waistline and incinerated his gut and lungs. He fell, foul steam exhaling from his screaming mouth. The third was hit in the ankle and calf of his left leg, the hip and the side of the head, and went over as if run into from the side by a truck.

Incinerat ecould mean MJ, or it could mean kj depending on if its cremation or severe burning.. either way its probably double-triple digit kj at least per bolt, and more possibly single digit MJ.

My hand fell against the lasgun on Penlan's back. Without thinking I twisted it round, find­ing just enough play in the sling, and fired without even aiming properly.

Either luck or the Emperor was with me, because she'd left it on full auto. As my panic-spasmed hand locked on the trigger a hail of las bolts sprayed the chamber, blow­ing chunks of ice from the walls and deafening us with the roar of ionising air and ice flashing into steam. The creature screamed and fled, even more terrified than I was, and as the power cell died and relative silence descended on our ringing ears, Penlan stirred.

..

I took a glance around the chamber. It looked bigger from down here, and the hail of las bolts had melted a number of small pits into the walls. Something seemed to be embedded in one, and I tried to focus on it, to stop my head spinning. Then my brain finally inter­preted what I was seeing, and I regretted my curiosity at once.

..

It was a human hand, severed at the wrist, the stump scored with vicious bite marks.

[/quote]

Probably at least double digit kj per shot considering the melting alone. I'll probably redo it anothr time, but its still neat. Also shows some hybrid thermal.explosive effects.

[Connor MacLeod]

Another small calc fest update, this time mostly the Necromunda stuff.. Plus more Caves of Ice


outlander

Page 110

A bullet wound punctured his thigh. The wound was burnt black at the edges, though not nearly neatly enough to be a las-blast. Scarr had been hit by a solid shell; nothing fancy.

Implies a 5 mm to several cm diameter hole for the wound. A few kj to blow through maybe through a thigh (tops) several times that for burns probably.

Page 112

He lay face down, his hood covering his face, but torn wide open at the back where a fist-sized hole piercecd cloth, flesh and skull alike. Dum-dums: nothing else could have left a hole in his head like that, not without a blast.

Fist sized hoel through skull. a few kj maybe to blow a hole through if it were a las weapon (and a las weapon could do that, I imagine thats what the 'blast' refers to.) a few tens of kj for burns inside probably.

Page 167

Up ahead of him, Berzel dissolved into a mass of smoke and flame. The lascannons mounmted in the windows had grumbled into life, swung about and cut Berzel down at the junction of their scything beams.

Earlier i'd noted it might have vaporized.. but "vaporize" could just mean blown apart. Probably a few hundred kj to several MJ if it was just blowing apart (grenade like damage) - its for both weapons. assuming 400 j per sq cm for the entire body we're talking several MJ

page 250

He had been hit square in the knee by a las-bolt. He couldn't stand on it at all.

Assuming a 10x10 cm burn we're talking 5-10 kj to burn.

Fleshworks
Page 28

The las-beam cooked the arm of one shooter, foring him to drop the weapon.

Depending on diameter of burn (2 cm for a finger-wide lasbeam) to 10 cm (for a bit more than the whole arm) and a 30-50 cm width for the arm (also if the tops/bottoms of arms as well as sides were burnt..) call it anywhere from 60 to 500 sq cm. 3-6 kj at least to 25-50 kj for burns. This is a heat ray note.

Junkition

Page 70
- here Kass notes tha tmost of the rats were "as big as a human baby", with tails longer than his arm.
Page 75

The next rat landed, scrabbled, snarled, and lost its face to a las-round. So did the next..

A few cm diameter hole.. maybe a few kj at least, plus another few kj for burns.

Page 76

The rat on my cuff yowled and scratcehd until I got enough wits back to jam the pistol against the side of its jaw and blow its head off.

Same as above.. a few kj again to blow a head or burn.

Page 220

There were alreaddy four Steelheads guarding the compound, three more were in Spyglass tower and two at the base of the trail. Neither side would back down and nobody could say who drew first. One badly gut-shot steelhead managed to drag himself almost to Wilferra's gates before he died and the other, bleeding, staggered up the trail as his gangmates ran down to meet him. They fired thunderous heavybore autogun bursts after the Firebrand who'd survived the initial exchange but by then he was a disappearing shadow. The other Cawdor was sprawled on the ground with half his head gone and his chest and belly las-burned almost to ash.

I've been trying to figure out a good way to calc this still, but it's occured to me it doesnt have to be total cremation. It even seems to work that way Assuming a 100-1000 W per square cm for burning (torhc like) And a 50-100 cm both for heigth and width (it IS a Goliath after all) of the torso.. 250 kj to 10 MJ depending on diameter (250 to 2.5 MJ for 50x50 cm, 1-10 MJ for 100x100 cm torso) Assume a few MJ, and that it takes the entire output of a lasgun (assume between 40-200 shots) 10-50 kj per shot. This is a heat ray weapon though, note.
IF we assume something like a flamethrower/wide dispersion effect it could be a few hundred kw to several mw for burning the torso in a few shots (Actually I figure a few shots, because the guy would retaliate.)
The interesting thing is.. the Necromunda rules seem to rule out Goliaths using lasweapons (except perhaps a laspistol, but other sources have suggested not), so it can't be some up-scaled Goliath lasweapon (makes sense, why would they bother making huge lasguns if noone but goliaths or Space Marines could use them?) so its probably a regular las weapon.

"Danil Vorens lowered his smoking laspistol and returned his attention to the viewscreen before him. A stunned silance filled the defence control room, the technicians agog at what had just happened. Lutricia Vijeon stared in open mouthed hoor at the corpse lying in the center of the room with a ragged hole where its face had been."

Part of a hole in the face? a kj or two could probably cover it, but it wouldnt be very penetrative. If any burning happened you might get into high single/low double digit kj depending on severeity of burns.

The carcass of our latest victim was lying a few metresfurther on in a wider tunnel that opened out from the one we followed. It was surrounded by chattering troopers and riddled with the cauterised craters of las-bolt impacts.
...
I gathered from the conversations around me that the ambull had just managed to get within arms’ reach of him before he finally succeeded in dropping it.
...
I glanced at the carcass, wondering if it was the one I’d shot before, but Vorhees had made such a mess of it blazing away on full auto that there wasn’t really enough left intact to tell.
....
It seemed that the thing had come at him along the main tunnel almost as soon as he’d entered it. He’d just been able to bring his weapon up before it was on him.
...
The pool of light from our luminators revealed nothing apart from the dismembered ambull.

Lasgun shots that blow off limbs and probably burn most of the body (cauterization). Creatures Anathema is 4 m tall, maybe 1/4 the width of the height (1 m across) 2-4 MJ for the burns (1-2 MJ if 50% of the body was burnt) Assume 1-4 MJ total. We know it was on full auto for a few seconds total (short duration between seeing ambull and dropping it, and we know full auto won't last long anyhow) If the powerpack was drained (40-200 shots) it could be as low as 5 kj to burn up to 100 kj (for 40 shots at 4 MJ) Does not include energy to amputate limbs (maybe single or double digit kj for limbs.. they're probably bigger than human limbs and certainly tougher.) several hundred kw sustained firepower probably.

She squeezed the trigger methodically, placing single shots on the head of the nearest ambull with commendable accuracy. aiming for the eyes and maw. A las bolt burst against the roof of the thing's mouth, blowing a large chunk of brain matter backwards which clung to the frozen wall, solidifying like an obsecne outgrrowth as the creature toppled backwards.

I'd guess maybe a 30 cm diameter head (like an insect).. double to triple digit KJ to blast hole through.. double digit kj for 3rd degree burns probably.

I fired by reflex, finding that my panic-spurred finger was able to tighten on the trigger just fine now that the question was a practical one, blowing a hole through its torso.

Laspistol must be blowing a 30-40 cm hole trhough the torso... assuming a 1-2 cm diameter hole. 5-10 kj (equivalent to Luke Campbell battle laser nearly) for that. not including burns (15-20 kj maybe for 3rd degree burns?)

The greenskin bellowed in triumph, but it was short-lived as Magot and I shot it almost simultaneously, and it dropped, most of its head blown away.

Pistol and rifle round blow away most of Ork skull again.. single/double digit kj apiece quite easily.

[Connor MacLeod]

Yet another thing I found. sometimes it astonishes me how much info I pack-rat away just because I might find it useful.. ugh... anyhow this mostly comes from newsgroups and such pertaining to the hard scifi stuff (or at least the people involved - eg John Schilling and Luke Campbell) who form some of the basis of the 'hard sci fi/atomic rockets' style analysis/research stuff. It's also all pretty old, so it may not be 100% accurate, but ti also shows a bit of the evolution of thought processes from 'magic heat rays that somehow vaporize stuff' to 'plausible laser death ray weapons.' And for me at least a bit humbling. I've attached the links, brief summaries, as well as tidbits from the links I found especially (if narrowly) relevant. There's actually alot of interesting (if differing) viewpoints and stuff and it makes interesting reading even apart from the laser gun stuff. someone even suggested using some sort of microwave weapon to raise intenral body temps (raise the temp on the brain by 20 kj and you might 'kill' it, which is a interesting and potentially unexplored avenue in sci fi - at least if you're going for more magical style energy weapons)



- Luke, energy output for lethal injuries from laser (10-100 kj)

http://groups.google.com/group/rec.arts ... a15261f97b

> energy requirements for effects similar to a rifle bullet;
> necessary resonator/emitter design features, and the likes.

This depends greatly on the nature of the laser beam. For continuous
lasers, forget about using it as a weapon against people by burning
holes in them. If it is too high powered, it will be blocked by its
own smoke and debris, so expect to take a couple seconds to burn a
hole through your enemy to reach his vital organs. Now you just need
to get him to sit absolutely still while the beam is doing its work,
while you hold the beam absolutely steady.
Continuous lasers might work better against people if employed as long
range flame throwers - give third degree burns to exposed skin, second
degree burns under light clothing, and ignite cloth for only about a
megajoule per square meter. Burns over your target's front torso,
arms, and face, plus burning hair and clothing, will likely be
immediately incapacitating (especially since he is now blind) and
ultimately lethal.
A single nanosecond pulse will cause a surface explosion. Pack on the
order of 10 to 100 kilojoules into the pulse for a blast big enough to
cause lethal internal trauma, disable limbs, and the like.
A train of nanosecond or sub-nanosecond pulses delivered about a
microsecond apart and lasting for a total time of around a millisecond
might be able to drill a deep hole into tissue with the subsequent
blasts, with effects similar to that of a modern bullet, all for about
a kilojoule in energy. If it works. No one knows if it does (or if
they do, they're not telling).

This is interesting largely for how it breaks down the nature of 'effect' vs 'efficiency' Heat rays are generally flamethrowers unless your magic raygun can emulate penetrating photons (X-rays/gamma rays) or a particle beam, which would probably behave somewhere between the two kinds of pulsed lasers. There's alsot he possibility of 'steam explosion' explosive damage, which might be more effective than a pure thermal effect but still less efficient than the pulsed weapons.

Given effects and the 'canon' descriptions of las-weapons the 'single nanosecond pulse' probably is the best, although its peentration is absolute shit. It's almost like a shotgun vs an armor piercing rifle - good against unarmored or lightly armoured targets and that's it. Type three would be more penetrative but wouldn't make the big crater-holes in the target - good if you have a high ROF and drill lots of bleeding holes in the target. You might be able to find some happy medium between the two depending on the energy content of the pulses and the number of pulses.

The third kind would probably be either a long las or hellgun type weapon (high penetration) although you might expect hellguns to combine the two ideall (blowing large holes through people.) An interesting variation would be one whose pulses vary.. one to drill a hole through armour (as the needle rifle has been knonw to do) and then the successive pulse or pulses blow the big holes in flesh.

On the second 'page' (25-50) he also says the following:

http://groups.google.com/group/rec.arts ... 5151fb295e

A 100 kilojoule pulse incident on a human torso would have about the
same effect as duct taping 20 grams of TNT to your target's chest and
then detonating it. This would undoubtedly crush much of the chest
and send rib fragments flying through lungs, heart, blood vessels, and
airways. Incident on rigid armor, the shattered peices of the armor
now become fast moving projectiles to perforate your target. If the
armor is thick enough to resist shattering, the shock wave can still
spall a layer off the back of the armor to act as fragments. The
shock wave itself might well be enough to cause ruptured bowels and
hemorrhaged lungs.
There are ways to make armor that resist this kind of damage, however.
Multiple layers of different density will cause multiple reflections
of the shock wave, weakening it as it passes each boundary. A layer
of kevlar under the rigid armor could stop spalled fragments.
10 kilojoule pulses would be about like the detonation of 2 grams of
TNT. Not having performed experiments of detonating various amounts
of high explosives against large mammals, I am not quite sure how
lethal this would be although it would certainly cause nasty injuries.
Hence this is about the lower range of my estimate for the minimum
energy for a single pulse that would reliably dispatch a human target.

The effects of such weapons above as well as means of protecting against it (possible indicators of how Flak armour is meant to work.)

While not technically a laser, page 'three' has this interesting tidbit which can pertain to any other weapons (RL spike/pulse weapons, ACS gravguns, tau pulse or many magnetic accelerator weapons in 40K, etc.)

Interestingly, at these velocities the projectile has enough kinetic
energy to completely vaporize itself upon impact, plus a considerable
amount of the target. The net resut is that you get a flash of plasma
from the collision, which expands violently creating a shockwave -
similar to the explosive effects of pulsed lasers discussed elsewhere
in this thread. Unlike the laser pulses, however, the vaporized
material has momentum in the direction the projectile was moving, and
the superheated gases and, later, recondensed bits of the projectile
and target can still punch through the target by the simple method of
this jet pushing the material of the target aside, similar in some
ways to a thumbtack being driven into drywall. Unlike a thumbtack,
the jet tends to disperse fairly rapidly. The faster the projectile
moves, the greater the ratio of the energy to the momentum, the
quicker the jet disperses, and thus the more the blast from the impact
comes to dominate over the penetrating jet of material. In the limit
of super-high velocities, the effect of the impact of the projectile
will be essentially indistinguishable from the effect of a laser pulse
of the same energy incident upon the target.
One problem is that when I tried to estimate the range of a projectile
moving fast enough to glow through atmospheric shock heating, the
results were rather dismal at earth's atmospheric density for
projectiles packing about a rifle bullet's worth of kinetic energy. I
seem to recall the range was in the high tens of meters at around 5 to
6 km/s. This would be suitable for sidearms, but not for the
applications met by today's rifles.

This echoes sentiments I recall hearing about Andromedaverse kinetic kill missiles hitting the hull (plasma blowtorch as I recall being said.)

Page "four" had this to say

One issue is that bullets from modern rifles are subsonic in tissue
(they are certinaly supersonic in air, however). These hypervelocity
pellets would be supersonic in tissue. Thus, while modern rifle
bullets will not cause a shock wave in tissue (a compression wave and
expanding cavity, certainly, but not a true shock) the pellet would.
It is not clear that this would necessarily lead to increased tissue
destruction, however. Shockwaves from explosions are known to lead to
pulmonary hemmorhaging and ruptured bowels, a shock from a hypersonic
pellet might do the same. The extreme stretching of the tissue in the
vicinity of the projectile's passage could also lead to increased
tearing. On the other hand, shockwaves lose energy to heating as they
propagate - this could lead to less energy being put into mechanical
disruption than with a bullet. Energetically, mechanical disruption
is two to three orders of magnitude more efficient at damaging tissue
than heating, so the development of a shock might well be
counterproductive.

Explaining why mechanical damage (EG making your lasers explode stuff) is generally more efficient than heat rays or steam explosions.. as well as providing an approximate ratio between the two. Do note that as a rule, explosions tend to be less effective than raw fragmentation as well - which is why many modern grenades are frag gremandes I believe - bone shrapnel might be quite effective there.

REally I'm kinda only highlighting relevant and number-y points, but the entire thread is damn fascinating both for the information it gives and the insight it shows on the development of stuff you see in Luke's page or SFConsim or Atomic rockets.

Lastly there's also this bit on velocities vs fragmentation

1.5 km/s is about the speed of sound in tissue. This varies according
to different tissue types, of course, but 1.5 km/s is typical except
for bone (which is about 4 km/s).
At 2 km/s nearly anything will be badly fragmented (tungsten
anti-armor projectiles possibly excepted), but vaporization does not
set in until you get to about 4 km/s.
I don't think there really is any sharp cutoff, more of a gradation
from puncture wound to tissue badly shredded by multiple fragments to
explosive effects.

I'm a bloodthirsty bastard for finding this fascinating.



- Schilling on 600 j pulsed laser pistol wound physics

http://groups.google.com/group/rec.arts ... fle&lnk=ol&

Whatever mechanism you use, though, if you can boil a quarter of a gram
of water in an arbitrarily short period of time, while it is still inside
the target's body, you'll get far more than a "nuisance skin burn". Think
in terms of nasty little steam explosions gouging out chunks of the target's
flesh. And, contrary to the standard SF cliche, the wound won't be neatly
cauterized.

"steam explosion" damage. We're talking ~600 J worth of flesh 'boiled' (rather, vaporized.)

Why do you need to do either? A "laser pistol" ought to be able to focus
its beam to sub-millimeter spot sizes at typical combat ranges, and if you
rapidly pulse the laser you can punch the hole in under a millisecond.
For the 600-Joule case, go with 30 pulses each of 20 Joules, at intervals
of ten microseconds. Each would suffice to vaporize about one cubic
millimeter of soft tissue, and ten microseconds allows enough time for
the debris to clear the beam path for the next pulse. 300 microseconds
later, you've drilled a hole a foot deep into the target.
And while the hole may only be a millimeter in diameter to start, it will
also be filled with steam at about 20,000 psi, which should open things
up a bit.
Or you could get the same effect with a single pulse from a 500 MeV electron
gun, which would deposit its energy along a track roughly thirty centimeters
long and one beam diameter wide.

this is more mild a description and analyiss of such weapons compared to Luke's, but it does show that depending on the mechanism you assume (or handwave) you could get significant damage from bullet levle damages or less. 20,000 psi I believe is also far less energetic than high explosive - you don't need to simulate HE to do damage. To be fair, I'm not sure what sort of wound diameter you're looking here. Probably not alot.





- Schilling on laser pistol energies, diff between thermal and mechanical damage, Luke discusses with Schilling

http://groups.google.com/group/rec.arts ... ser+pistol#

I'm not going to really quote this one, because it's basically the extended edition of the atomic rocket's sidearms energy weapons highlights. The only interesting tidbit was that flashlight batteries were .5 kj per cubic cm and lithium batteries get up to 3 kj per cc.. which offers a nice variation between performance thresholds. The thread also has some interesting stuff about Luke discussing wounding mechanisms.




- Luke, continuous beam laser thermal damage, pulsed laser effects.

http://groups.google.com/group/rec.arts ... 38adfea396

This depends a lot on the characteristics of the beam. With a
continuous laser, you'd have a hard time getting your target to stay
still for long enough to bore a deep hole into it. I have estimated
that for continous beams, you'd need about 500 kilojoules to cause
incapacitation and/or death, with the best option to defocus the beam
to expose much of the frontal area of the target to the beam. This
will cause third degree burns to exposed skin, second degree burns
underneath light clothing (like cotton t-shirts, demin, or typical
summer miliatry uniforms) and will ignite cloth.
Short pulses will tend to be absorbed near the surface, causing an
explosion, and will be obscured by their own debris and smoke. A
single explosion could probably cause rapid incapacitation and/or
death with about 10 to 50 kilojoules delivered to the target. Smaller
energies would probably just maim or injure but not kill.
The best idea seems to be to deliver sub-nanosecond pulses. At these
time scales, most of the energy of the beam is transfered to a shock
wave in the material the beam is incident on, turning light energy
into mechanical energy. It is much easier to damage people or
materials with mechanical damage than thermal damage, by about two or
three orders of magnitude. To cause damage to deep internal organs,
deliver a train of these sub-nanosecond pulses spaced, say, a
microsecond or so apart. Each one will cause an explosion at the
surface where it is incident on the target. This will drive the
expansion of a cavity in the medium upon which the beam is incident.
Comparing this to the cavity caused by the passage of a bullet, this
cavity is likely to stay open for about a millisecond before
recollapsing. This allows subsequent pulses to be incident on the
back of the expanding cavity, each of which explodes and starts a new
cavity expanding. These cavities reinforce each other in the forward
direction, causing enough stress to rip flesh or other whatever
material we are shooting at, allowing the beam to propagate deeply.
Each pulse can thus have an energy of around a joule or so, and the
full train of pulses would carry about a kilojoule. This idea may or
may not actually work, if it does, you could cause damage very similar
to that of a bullet for about the same amount of energy.

Elaboration of the previous themese and theories. you might call it 'laser flamethrower, laser shotgun, and laser rifle' I suppose . Those are how I tend to think of it.

Another interesting thing (and more shotgun like) was this:

To cause more damage than simply driving a hole through your target,
try focusing two beams of femptosecond pulses onto your target, close
enough together that the cavities from their explosions will overlap.
This may cause the flesh (or other material) caught between the
expanding cavities to rip, connecting the cavities. Rather than
driving a hole, it cuts a swath out of your target. This will cause a
greater surface area of the wound from which to bleed from; it gives
you more of a chance of cutting major blood vessels, nerves, tendons,
or the spinal cord; and more chance of damaging vital internal organs.
Use enough closely spaced beams and you will be cutting your target
in half (or nearly so). Again, this idea may or may not work.

The so called 'fanbeam' - I wonder if this would work in a conical effect.



- Luke, wattage to ignite clothes. Prior page is Schilling on 3rd degree burns skin intensity.

http://groups.google.com/group/rec.arts ... pon&lnk=nl&#

If it helps, my colleages that work with lasers all generally have small holes
in various articles of clothing where the 10 watt lasers they were working
with ignited spots on said clothes.
Based on what I'd seen of the J/cm^2 needed to ignite various fabrics, between
about 20 and 80 J/cm^2 would do it if you've got dry vegetation.

Schilling notes the 50 j per sq cm figure often used, which meshes with what I know more or less (there's no hard and fast boundaries ot third degree burns, methinks)



- Schilling, a laser needing 10x more energy than bullet, batteries and the like.

http://groups.google.com/group/rec.arts ... d58326fcad

The best available batteries are good for about 500 kilojoules per kilogram,
or 1000 kJ per liter. However, the *power* density is less impressive; it
is usually not possible to get the energy out in less than a minute or two.
Again, clever tricks at the laboratory stage of development may change this;
I've seen reports of a 400 kJ/kg battery that can discharge in less than
five seconds - but not nearly ready for production, and with the bothersome
limitation that it only works at temperatures above 400 degrees centigrade.
Chemical propellants are typically at about the 5000 kJ/kg level, and have
no trouble with high-rate discharge.

The temperature issue reminds me alot of sodium sulfur batteries, but I think that molten salt batteries have similar issues.. and molten metla ones I've seen have lousy rates of discharg (the power density) But the 400 kj/kg is what might fit better with lasweapons. The idea that lasweapon charge packs can emulate chemical propellants is hardly unreasonable either and might be quite possible given what we know and the comparison of las to chem propelled weapons in genera (EG why we see no lasguns running on combustion)

Note, however, that these numbers cannot be directly compared with a
hypothetical laser weapon. The human body is mostly water, which is
not particularly strong but absorbs heat better than just about anything
else around. So a laser weapon will probably need to deliver an order
of magnitude more energy to produce the same effect as a bullet.

This is older and more tenative than the latter analysis (it precedes the pulse train stuff) so it not strictly true. Rather I think of it as being indicative of what a 'steam explosion' non, pulsed laser might do (Luke has mentioned simliar comparisons 40 kj to drill a 1 cm wide hole through a body without pulse trains, which was about an OOM less than what a bullet or a pulse laser could do.)
At tens of kj you might expect some residual burning, if not cauterization or cauterizaiton like effects.


- Laser sidearms in "the 10-20 kj range" (schilling)

http://groups.google.com/group/rec.arts ... pon&lnk=ol&

So are lasers that make lighting-bolt style ionization trails. Lasers in
the 10-20kJ range, suitable for small-arms use, are still visible but not
nearly so spectactular. In the same range as rifle and machine gun muzzle
flashes, from what I have seen of both.

given the magnitude of energy involved and the comparison I'm guessing we're talking rifles sustained outputs, although it might be per shot (oom more than a bullet)



- More of luke on laser sidearms at 10, 100 kj levels. Also potentail battery stuff.

http://groups.google.com/group/rec.arts ... 0kj&lnk=nl&#

Supposing materials are developed with perhaps 50 times the tensile strength
> of steel (say 2.5x10^10 N/m^2), what figure would you place on the
> superconducting power cell's energy storage capacity, assuming a reasonable
> safety margin?

That is very roughly the tensile strength of single walled carbon nanotubes
(the exact value of which is not known all that well, my sources say about 30
GPa). This would give an energy density of about 30 MJ/liter (for the carbon
nanotubes, 25 MJ/liter for your hypothetical material). With a density of
around 1.3 kg/liter, this gives a specific energy of around 23 MJ/kg.
Engineering safety factors are usually around 2 or 3, depending on what kinds
of shocks you expect the power cell to experience, you get practical specific
energies of 12 Mj/kg to 8 MJ/kg. Figure a little loss due to the variance in
the magnetic field for the torroidal winding geometry (maybe 30%) and then add
in a fudge factor of up to 2 in either direction because the tensile strength
of carbon nanotubes are not all that well known

Again what is proposed here is not out of place given what we know of 40K materials science and weapon performance (or it scomparisons to other weapons.) note of course storage capability is not the same as dischrage.

> Of course, with such ample ammunition, you'll want to increase the
> punch of a single shot to 5 or 10KJ to ensure lethality (still
> 300 shots in a magazine!). I wonder whether the pulse train
> concept would still work? I guess too much plasma and debris, and
> irregular blast effects, could interfere with that.

My guess (and that is all it is, just a guess) is that higher powered pulses would
create a larger cavity, for deeper penetration and a wider wound channel. You
would still need to deliver all the pulses in about the same time (a few
milliseconds), since the time for the cavities to re-collapse is not changed much
with a larger pulse.
> Then again, you could even pump out 100KJ blasts for devastating
> effects. You'd still have 30 rounds, like a comparable assault
> rifle magazine. (8-.

The shock waves from the individual pulses in the pulse train might add together
since shock waves travel faster through already shocked matter and can combine into
a single, stronger shock. If so, once the shocks have combined, you would get the
explosive effect of a single 100 KJ pulse. The question is whether most of the
shocks will combine while still propagating through the person. Also, for
spherical shocks, the shocked matter tends to relax back to close to its unshocked
state after a certain time has passed, so the shock waves might only combine into
one in the forward direction. You might get a cone of disruption blasting anything
anything in the forward direction.
Even if the shocks do not combine into that of an explosion with a similar
detonation energy, a defocused beam could cause severe burns (the "flamethrower"
concept that has been discused before).
Alternately, a very powerful laser might be able to discharge a single 100 kJ
pulse, which would cause severe damage, equivalent to about 25 g of TNT. This is
about the level of inertial confinement fusion laser outputs.

The effects. Honestly this is probably closer to my 'new' visioning of non-thermal (non cauterizing) military lasguns and hellguns. Bear in mind penetration still sucks, so a good lasweapon might have variable 'modes' even still (CW flamethrower, single pulse, and multipulse.)




- More luke campbell, 100 kj laser effects

Page 1: 100 kj laser pulse, explosion.. visual effects, also effects of hypervelocity impacts

http://groups.google.com/group/rec.arts ... wer&lnk=ol&

Once you have enough power to do serious damage to a human, it might be difficult to armor that person. Kevlar vaporizes much more easily than flesh, the beam will burn right through bullet proof vests. Spectra not ony vaporizes easily, it also catches on fire. The difference between the energy needed to varporize steel and that needed to vaporize tissue is much less than the difference in the forces needed to rupture steel compared to that needed to
rupture flesh. A plate of steel that protects against bullets may not offer
significant protection against a focused beam.

'benefits' of a laser weapon over other kinds of weapons. It's dependent upon designa nd thickness, but the 'advantage's are still telling I'd think, especially in how it pertains to 40K armor design (needing to protect against more than just bullets will invariably force compromises that will affect thickness and ability to resist other kinds of attacks.) You also get lots of other advantages of course

Not just an assasination weapon. Expect to see front line infantry using guns
like this. If the power supply can be made compact enough, the ammunition will
weigh much less, so an individual soldier could carry a lot more shots for his
gun. In addition, higher velocity projectiles are better at piercing armor.
At 2 to 4 km/s, you can use tungsten or uranium projectiles that will punch
through steel plate. At 6+ km/s, any material will vaporize, creating an
explosion and an armor piercing jet that can get through even more armor.
Finally, the higher the velocity of the projectile, the lower the recoil for a
given amount of energy of the projectile. With a method of compact energy
storage, these electromagnetic projectile launchers have every advantage of
modern bullets, and some advantages of their own, as well.

Fun HV impacts again. Imagine variable setting projectile guns


Page 2 100 kj laser pulse, one pulse
http://groups.google.com/group/rec.arts ... wer&lnk=ol&

If you can create short duration, high power pulses of light, you can create
explosive vaporization at the surface of the target. This explosion could
create significant interior damage. For example, imagine a 100 kilojoule, 1
microsecond pulse of light focused into a 1 cm spot. This has the approximate
energy of 20 grams of detonating TNT and is delivered over about the same time
scale. Imagine straping 20 grams of TNT to your body and then setting it off.
Current weapons lasers do not do this, they all have continuous beams, but look
at the sorts of things that the high power pulses used by lasers designed for
inertial confinement fusion do.

Ouch!


Page 3: 100 kj train of pulses

http://groups.google.com/group/rec.arts ... wer&lnk=nl&

just found out this morning that a mere 10 joule pulse of light from a ruby laser
can pierce a 2mm slab of steel. Admittedly, this is a highly focused pulse at a
slab that is near the beam optics, but that laser was still able to propagate its
light through 2mm of steel in order to burn a 0.1 mm hole. This is with a pulse
lasting perhaps 10 ns. If the pulse energy were merely absorbed in the first skin
depth or so of the steel (maybe 0.01 mm?), you would expect a minor explosion with
a 10 joule energy, and that is nowhere near enough to penetrate the 2 mm slab.
Somehow that pulse was able to burth through with approximately the same beam
profile as it has in air.
Given this, is there any reason to expect that a highly focused train of pulses
could not penetrate deeply in solids? Imagine a train of one hundred 1 kilojoule,
10 nanosecond pulses spaced 1 microsecond apart. Assume these are made of 500
nanometer green light, focused by a 10 cm aperture beam pointer at a target 100
meters away. This gives a spot size of about 1 mm diameter. It takes slightly
less than a 3 kilojoules to vaporize a cubic centimeter of tissue, so each of those
kilojoule pulses will be evaporating a cylinder about 40 cm deep if the beam
propagates through tissue with the same beam profile it has in air. It may be
difficult to keep a 1 mm wide beam through 40 cm of vaporizing tissue with
turbulent plasma and gasses acting as lenses to disperse the beam, so say each
pulse only vaporizes a 1 cm deep section of tissue (corresponding to an average
diameter of 6.5 mm). Each subsequent pulse in the train will vaporize another 1 mm
deep, assuming the beam does not stray by more than 6.5 mm in the 0.1 millisecond
it takes to deliver all 100 pulses (at 100 meters, this is an angular spread of 65
microradians, so the gun would have to track at 0.65 radians per second or less, or
37 degrees per second or less). This generates a hole from vaporized tissue alone
that is one meter deep - much thicker than most people. The explosive vaporization
of that tissue will casue additional damage, and that will be damage to the deep
vital organs. On top of that, pulses that detonate in the bones can send bone
fragments flying through the body, which can also pierce vital organs. On the
whole, this sounds quite lethal.

Even more "ouch" - this is definitely how I think a hellgun would work.





- Schilling on pulse lasers, pressure for micro explosions, etc. (multi pages - next page and onward)

http://groups.google.com/group/rec.arts ... ude&lnk=ol&

rather doubt you'd be in any condition to - "megajoule pinprick" is
pretty much an oxymoron.
And you seem to be making the implicit assumption that "vaporize" equates
to "disintegrate", and that having determined that since X ammount of energy
delivered in a certain manner will vaporize a hole of diameter Y and depth
Z in a human target, the only effect on the target will be a cylindrical
region of mysteriously vanished flesh of diameter Y and depth Z.
In fact, what you get is a cylindrical region ofi diameter Y and depth Z,
filled with the vaporized flesh. In other words, hot, high-pressure
steam - about twenty thousand pounds per square inch, by rough calculation.
This will rapidly cause far more damage than just a neat hole of diameter
Y and depth Z - I'd guess that a such steam-filled cavity with an initial
diameter of a millimeter or so would be more than enough to incapacitate
(or worse) most any foe.
It also has implications regarding the pulse frequency - for maximum
effect, you probably want each pulse to arrive just as the steam
microexplosion from its predecessor has reached maximum expansion,
to minimize absorbtion by the steam and other debris and so maximize
penetration. And you'd also want to avoid laser wavelengths near
H2O absorbtion bands. On the other hand, maybe you'd *prefer* massive
surface damage to deep penetration, for some applications.

Rather interesting and useful for the discussion of how the 'pulse explosions' work.. as well as explaining why so oftne people react badly to 'megajoule' laser weapons in sci fi vs debates. I suspect they actually do think MJ pinprick, when something like that would be explosive (as opposed to MJ flamethrower, or MJ incendiary, or something else - its how the energy is delivered to the target that influences those things, of course!)



- Page 2 (switches to 'Force fields')
http://groups.google.com/group/rec.arts ... ude&lnk=nl&

But let's be pessimistic, and assume a skin depth of a tenth of a
millimeter. Given a laser spot one millimeter in diameter, we need
a pulse energy of approximately 0.5 joules to vaporize the target
to one skin depth. We then ought to let the vapor cloud expand and
clear the spot before sending the next pulse - with a characteristic
length of about a millimeter and a thermal velocity of about 400 m/s,
this will take 2.5 microseconds.
So we need a laser with a pulse energy of 0.5J and a pulse frequency
of 400 kHz to punch a millimeter-wide hole through flesh with optimum
performance. If we want a total penetration depth of 30cm, we need
a total of 3,000 pulses over a period of 7.5 milliseconds, or a total
energy of 1,500 joules. This is comparable to the muzzle energy of
a 5.56mm NATO rifle bullet, and with the hole being blasted out to
4cm diameter by steam pressure it is probably about as lethal.
There is still the question of focusing the laser spot down to a
millimeter's diameter and holding it on target for the requisite
7.5 milliseconds. Probably you'd want to use an adaptive-optic
beam director with the largest aperture you can fit, coupled to
a gyrostabilizer and a rangeinder. Use the first laser pulse to
get the range, then cut loose with the next 3,000 at proper focal
length.

I also like this response for his argument as to why muskets are superior to modern rifles if one objects to lasers on the basis of compelxity (EG Just using a slugthrower rather than a laser)



Page (dunno) - velocity of steam at 100C, etc

http://groups.google.com/group/rec.arts ... ude&lnk=nl&

The thermal velovity of steam at 100 degrees centigrade is a bit over
400 meters per second, and against zero or negligible resistance (and
to 20,000 psi steam, even human flesh offers negligible resistance),
we can expect the steam to expand at that velocity.
Since the spot size is one millimeter, most of the vapor should clear
the beam path in (0.001 meter)/(400 meters per second) = 2.5 microseconds.
Actually, when I do a rough calculation of the time required to push
the surrounding tissues out of the way, the time goes up to a whopping
four microseconds. So a 250 kHz beam for 12 milliseconds might be more
appropriate.

This page offers an interesting comparison of types of explosions, and the 'steam explosion' above is more akin to a low explosive (still dangerous and effective at creating wounds, but its not turning a body into a bomb, exactly.) The other indicator of course is the expansion velocity. Speed of sound in water is 1500 m/s (which is roughly that for flesh) and HE tends to be multiple km/s routinely.


- Schilling - OOM difference between pulsed and CW lasers

http://groups.google.com/group/rec.arts ... 28eae2fdd2

Mechanical damage by vapor explosion is a *much* more efficient kill mechanisim
than simple heating - cuts the required laser size and energy by about
an order of magnitude.

Its not an exact 'ratio' but its a reasonable approximation for the reasons I outlined above.



- Laser pistol/SMG analogue - Schilling, weapons range, diff between "sidearm" and "rifle"

http://groups.google.com/group/rec.arts ... 681a308948

Unfortunately, the energy requirements for an effective CW laser weapon are
prohibitive even with the sort of storage systems we are talking about here.
Taking the pulsed laser handgun discussed earlier as a baseline, and insisting
on being able to sweep at 5 degrees/second while still cutting at least 5cm
deep in flesh, results in a power requirement of over half a megawatt. Or
maybe a single second's worth of continuous fire from the powerpack.
I'll stick with rapid pulsing - 20, 1000J shots per second should give the
rough equivilant of an Ingram M-11 machine pistol but with zero recoil and
almost thirty seconds of fire without reloading. Or if we get stuck with
energy storage an order of magnitude less than the ~10 kJ/cm^3 materials
limit, 10 pulses per second for 5 seconds. A 50 meter effective range
seems reasonable either way.

CW vs pulsed laser again,a nd this is just for handguns


Also this tidbit

If you've got an order of magnitude more energy storage in
a rifle "magazine" than a pistol, you can get an order of magnitude more
range and penetration, all other things being equal.

This seems to be more for particle beam weapons than lasers, but given some handwaving of lasguns as PB-like weapons is possible it could still apply


Some non laser weapons. The explosives and tank gun stuff was interesting

- Luke, nonlethal damage mechanisms (thermal and such)

http://groups.google.com/group/rec.arts ... ser+weapon#



- schilling on tank guns and such

http://groups.google.com/group/rec.arts ... pon&lnk=ol&#



- Super explosives (chemical improvement)

http://groups.google.com/group/rec.arts ... ude&lnk=ol&