assumed they did local vaporisation (part of me still does.), but I admit that was a certain bit of naivete on my parrt. Its way more complex than that. Other 40K weapons are fairly straightforward - plasma guns vaporize and/or cremate, meltaguns melt/vaporize, and even bolters and ballistic weapons are more easily calced (projectile weights and recoil are good indicators.) Hell, even hellguns have been easier to calc.
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.
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:ATomic Rockets wrote: Whether you use lasers or particle beams, you'll need a bit over a kilojoule of output energy to reliably incapacitate a human target. In the case of a laser weapon, that energy would be subdivided into ~1 joule pulses at ~5 microsecond intervals, to achieve penetration in the face of a laser's natural tendency to deposit energy at the target's surface. Particle beams don't have that problem; boost the electrons up to a few hundred MeV, and you can dump the whole kilojoule's worth at once.
The plasma clears away easily in that time frame; debris is the real issue, and the driving force between the 5 microsecond pulse rate. That allows roughly 90% of the debris to clear the beam path, assuming a 1mm beam and instantaneous 1J pulses. 1 joule every 5 microseconds is optimal against soft tissue, other materials will want different pulse trains
atomic rockets again wrote: I assume that since the beam is one millimeter in diameter but the hole in the pirate is four centimeters, little or no wound cauterization will occur.
Nope, the wound would be ragged and messy. It is created by mechanical, not thermal effects.
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.)
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.)
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.
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.
Lotsa links will be following. Like with my last little (ha ha, "little") essay, I'll post the links, with the relevant tidbits. Bear wiht me, this will be MUCH longer...
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.Adventitial tissue temperatures below 80 degrees C were not associated with appreciable welds, while equilibrium temperatures between 95 degrees C and 140 degrees C were consistently associated with effective mean weld strengths, which increased linearly from 25 to 110 g, respectively. Temperatures greater than 150 degrees C were associated with rapid tissue dehydration and charring. These data suggest that the therapeutic range of tissue temperature that provides effective thermal fusion of intima-media separations is broad and that the depth and degree of thermal coagulation can be controlled by manipulation of laser energy delivery.
Again, note that coagulation and cauterization is used interchangably. Also note the references to "charring" and associated thermal damage. Also notice the 110 C - 270 C temps associated with "medical" cauterization. Which, again, hints my use of "boiling point" is grossly conservative (and this is still for medical purpsoes, much less military ones.)There are several disadvantages to the conventional electrosurgical unit, which include tissue adhesion to the electrosurgical unit tip, significant charring of tissue, generation of significant quantities of smoke, and ineffective coagulation of bone and other high-impedance tissues. With argon-enhanced coagulation, the argon beam displaces oxygen and nitrogen, limiting oxidation of tissue and resulting in less combustion and therefore less carbonization (charring) of the tissue, less smoke and odor, and less tissue adhesion to the electrode tip than in standard electrosurgery. This combined with the lower power settings that can be employed with the argon gas surgical unit contributes to decreased tissue destruction and necrosis. The conduction of current by the argon beam allows for effective coagulation of even high-impedance tissues such as bone. When tissue is being cauterized with an argon gas surgical unit, the tissue temperature never exceeds 110?C because of a cooling effect from the argon gas and because no further conduction of rf energy occurs once eschar forms; in contrast, with conventional electrosurgical units, tissue temperature is approximately 270?C. This precise flow of energy allows the user to coagulate tissue in a more efficient and controlled manner.
Note that this does refer to "electrocautery" rather than laser cautery (or laser vaporization, again the terms seem interchangable in that regard), but the effects are still thermal, so the results should be approximately accurate (especially since they dont need to be precise or controlled.)
Again we have a link dealing with lasers and cautery/coagulation. note that they also use the term laser vaporization in the same arrticle, so the effects are (no surprise) much the same, given the temepratures involved. The quote above, of course, notes that the 80-100C range is considered appropriate for "medical" purposes, but "conventional" laser therapies go with 300+C temps. As I noted before, its clear that my initial beliefs were grossly underestimated.The Indigo® laser treatment system has unique characteristics that define it as a minimally invasive thermal therapy rather than as a conventional laser therapy, even though the name suggests the latter. The temperature in the prostate during Indigo® ILC rises at a steady rate and is in line with other thermal therapies (80°C to 100°C) rather than conventional laser therapies (>300°C).
At temps of "many hundreds of degrees", up to 800 C. This indicates nearly an order of magntidue higher temp than I assumed before (Its close to cremation level temps, I should add.)By modifying the waveform of this current, the physician can use it to coagulate or dehydrate the edges of the severed tissues, thereby arresting bleeding in certain surgical operations. This type of electrosurgery generates tissue temperatures of many hundred degrees Centigrade (up to 800 degrees) most RF generators in common use today are intended to achieve both RF cautery and blood coagulation.
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.)Irreversible damage to tissue (i.e., denaturation of tissue proteins) occurs at temperatures greater than 47 degrees Centigrade.
Again, as above, this tends to suggest lower temperatures can ALSO lead to damage (something I suspected and never denied, because I'm sure someone will point it out), but that its not really changing anything, and as noted, much higher temps are routinely used, (and have been), in medical procedures, so it must not be an absolute. (The fact that its referring to intneisities tends to reinforce the "localized effect" issue.) And also remember that in medicine, lower temps to achieve the results are desirable to limit damage (indeed its the higher temps that result in the damage we need.)Beyond that point, greater current intensities tend to heat up tissue too much, elevating tissue temperature to 100 degrees Centigrade and above and thereby causing carbonization of the tissue in the immediate vicinity of the electrode tip. This carbonization in turn increases tissue resistance to further passage of current (i.e. tissue impedance), which limits the extension of the lesion to a thin tissue shell surrounding the needle tip.
Again note "400-600" C temps, associated with electrocautery.Electrocautery uses high temperatures (400 degrees to 600 degrees Centigrade) to remove tissue, which burns and chars surrounding tissue, and frequently leads to significant post-operative pain and long recovery periods. Coblation applies bipolar radiofrequency (bRF) energy to a conductive solution, such as saline, to create a relatively cool (40 degrees to 70 degrees Centigrade) plasma field, which virtually dissolves tonsil tissue, preserves healthy surrounding tissue and can seal any vessels that bleed.
This seems to indicate cauterization can occur at up to 1000C. Possible, but I admit that this source makes me a tad leery given some of the later statements. This is probably the leastAs the RF energy is applied, frictional heating of tissues results, with cell death occurring at temperatures between 60 and 1000º C.
reliable of the statements. I suspect that they may be off by an order of magnitude temp-wise on some of the temps. (So in this case 1000 C is 100 C)
This is perhaps the MOST reliable of the temps.. note the "60-100C" is accurate, so it is likely the representation of electrocautery might be accurate. (especailly since it is indicating that Electrocautery is much higher-temp and excessive.)The high frequency radio surgery and its results should also not be confused with diathermy, electric cauterization, or spark producer. With radiofrequency, the targeted tissue temperatures stay localized within a 60-100°C range thus limiting heat dissipation and damage to adjacent tissue. In contrast, electrocautery, diathermy, or laser temperatures are significantly higher (750-900°C) which result in a very high heat propagation, which is far in excess of the desired therapeutic need (6).
Sorry, but at 1000C you're way BEYOND boiling point for water (100C). You're well into cremation level temps at that point. Water would have long vaporized at the point of 1000C.he cellular water in the soft tissues gets heated and when the temperature reaches 1000C, it starts boiling and produces steam, which results in cellular molecular dissolution of individual tissue cells. The cells exposed to these waves are destroyed while the surrounding tissues remain unaffected
Still, it *might* be accurate, but I have my doubts.
Again, 1000C and 5000C are WAY too excessive for surgical temps as far as I can tell. I think what they mean is 100C and 500C, which would be more plausible given the overall context. 500C would definitely cause "third degree burns", excecssive smoke, gross scarring, and charring. Its still much higher than the boiling point temp I used before, though.
RADIOFREQUENCY ELECTROCAUTERY OR BOVIE
Simultaneous cut and coagulation. Requires different modes and adjustments for different applications.
Minimal smoke production. Produces excessive smoke.
Minimal surrounding tissue damage. Tissue damage like 3rd degree burns.
Heats tissues below 1000 C. Raises tissue temperature above 5000C.
Sterilizes tissues under application. Can cause postoperative sepsis.
Minimal scarring creates soft supple scar. Gross scarring and fibrosis.
Faster healing. Slow healing.
Again, see that 100C is consiervative, temps in Excess of 300C are mentioned for "tissue dessication, char formation, etc."The saline couples radiofrequency electrical
energy into tissue in which it is converted into
thermal energy. The flow of saline provides cooling to
limit peak tissue temperatures to 100°C or less (Fig 1).
This is contrary to conventional electrosurgical devices in
which tissue temperature can easily exceed 300°C, resulting
in tissue desiccation, char formation, smoke generation,
electrodes sticking to tissue, and undesired lateral
I only mention this because it notes that long timeframes (15 minutes) in this case are associated with the lower temps (95C here) This makes sense, after all. You can reach a certain energy threhshold (ie melting something) by prolonged heating at lower levels, or a single large injection of energy, even though the two differe. (depending on the results, the latter is generally more efficient, since it gives less time for energy to radiate away. But its much less precise and more damaging to surroundings.)In our experiment, once the needle
had been inserted and deployed in the liver parenchyma,
the generator was used for 15 min in the
mean-temperature-control mode with a threshold
set at 95°C.
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.)Conventional monopolar electrocautery is also associated
with much higher tissue surface temperatures than with the
Aquamantys System with temperatures reaching in excess
of 300°C. The higher temperature associated with
conventional monopolar electrocautery results in a charring
of the tissue or bone surface, smoking, and the
development of a superficial coagulated blood plug which
temporarily stops bleeding. This plug often cracks or is
dislodged resulting in intraoperative or postoperative
rebleeding from the site.
Same site, essentially a repeat of the previous evidence phrased just a bit differently. 300 C temp vs 100C, mention of charring and scar formation along with cauterization. STill, its useful supplementary data.The saline used as a conductive fluid at the tip of the
BPS5.0-VT device (Figure 2) also cools the tissue surface
and prevents the surface temperature from exceeding 100°C.
The use of standard electrocautery results in the
tissue surface temperature exceeding 300°C. The use of
standard electrocautery also leads to charring of the tissue or
bone surface and scar formation.
Nothing specific on temperature, but this does reinforces the idea that lower temperatures (used in many procedures for cauterization or cutting) deliver much less energy (and lower temps) over a longer period of time (many seconds or even minutes), whereas the other "higher" temperature proceesses like laser or electrocautery (interesting inasfar as they are noted similar) are shorter-term and much higher temp."As tissue begins to heat above 60 degrees C, it begins to desiccate, blanch white and shrink as proteins denature, and flash boil at temperatures somewhere over 100 degrees Centigrade. In tissues with normal blood flow, temperatures below about 45 degrees C are non injurious. Higher temperatures cause irreversible damage, and tissue death and coagulation is time dependent to some degree. One can raise tissue temperature to a higher degree for a very short period of time with no tissue death occurring, while at the same time if one prolongs temperatures in the lower range for many seconds, then tissue death will occur. The generation of heat should occur quickly when using laser or electrosurgery to cut, so that we generally ignore this time variable."
Also of note is that there is a chart attached that indicating at 100C and above is where "vaporization and charring" occur. We can conclude that any vaporization that occur in these calcs will be factored into the overall temp (IE we don't have to really factor vaporization sepaarately)
Tomorrow or in a day or two I'll present a few examples (already mentioned in past debates) to possibly demonstrate how it works. It'll be a bit complicated, and I kinda want to get some feedback and such first.