Realistic Plasma Weapons

[Purple]

Everyone who has read the main site will immediately shout to say that plasma weapons can not work as according to the laws of physics. And whilst this is indeed true for the glowing blobs of gas we see flying on screens it is not entirely correct. After all, we today have a form of weapons that do exactly what plasma weapons are supposed to do (penetrate armor) and with about the same damage mechanism (super hot jet of vaporised metal) we call shaped charges. So that got me thinking. For the sake of cool, I want to design a mostly realistic plasma weapon that can work as advertised by the laws of physics. All I want from you is general input on the idea and concept after I lay it out.

What I was thinking off is a weapon that is in essence a scaled up battle rifle firing 25-30mm (maybe even 35mm) shaped charge grenades. Recoil would be mitigated by the fact that the soldier using it would be wearing power amour. Also, becouse the shaped charge projectile would be much lighter than the equivalent solid slug and hence require less propellant that would decrees the kinetic energy of the whole thing this further help mitigate the recoil to something that is sort of controllable in full auto fire (think FN FAL equivalent). All in all, this is a rather low tech solution to any sort of powered armored enemy maybe even up to 40K space marine level.

So, what do you people think? Is it a valid SF concept to use?

[Rabid]

Query : more details requested on the mechanism of the shaped charge.

Is it a shaped charge like those we know today (chemical reactions) ? Or an electromagnetically confined blob of superheated plasma ? Is it some sort of miniaturized Casaba Howitzer ?

[Purple]

I was thinking a normal shaped charge like the ones used in modern RPGs. An explosive triggers the melting of an inverted copper cone, the cone burns through anything in front of it. After all 7-10 times the diameter (25-35mm) yields some 175-350mm RHA penetration. And realistically, short of magical shields that is more than enough to penetrate anything that infantry are reasonably to be expected to carry over his center mass even with power armor.

I am definitively looking to avoid any sort of magnetically contained plasma blobs. That is both a cliché that has been overused way too much in SF and is extremely unpractical not to mention horrifically costly for the price of a basic infantry weapon.

[Rabid]

Well, in that case I think such a weapon could be built with today's technology.

We have 25mm automatic grenade launchers, that could be scaled-up to 35mm, and fitted on an exo-skeleton like this one (upgraded with military-grade component and covered with kevlar/ceramic plates to cover against small-arms rounds, obviously).

It would need a bit of R&D, sure, but the whole system could be operational and used on the field in 10-15 years. It could be used against enemy APC and other lightly armored targets. It could a bit more economical than anti-armor missile, and it would be more mobile than crew-served weapons. Plus, it could allow for a greater mobility in a urban environment.

[GrandMasterTerwynn]

Everyone who has read the main site will immediately shout to say that plasma weapons can not work as according to the laws of physics. And whilst this is indeed true for the glowing blobs of gas we see flying on screens it is not entirely correct. After all, we today have a form of weapons that do exactly what plasma weapons are supposed to do (penetrate armor) and with about the same damage mechanism (super hot jet of vaporised metal) we call shaped charges. So that got me thinking. For the sake of cool, I want to design a mostly realistic plasma weapon that can work as advertised by the laws of physics. All I want from you is general input on the idea and concept after I lay it out.

What I was thinking off is a weapon that is in essence a scaled up battle rifle firing 25-30mm (maybe even 35mm) shaped charge grenades. Recoil would be mitigated by the fact that the soldier using it would be wearing power amour. Also, becouse the shaped charge projectile would be much lighter than the equivalent solid slug and hence require less propellant that would decrees the kinetic energy of the whole thing this further help mitigate the recoil to something that is sort of controllable in full auto fire (think FN FAL equivalent). All in all, this is a rather low tech solution to any sort of powered armored enemy maybe even up to 40K space marine level.

So, what do you people think? Is it a valid SF concept to use?

So, if I gather what you've read correctly, you simply want to make a shaped-charge round sound cool by tacking the word "plasma" in front of it. Which fails miserably because the jet of metal produced by a shaped-charge round is NOT the same as a jet of plasma. The shaped charge achieves its penetrative effects by smashing the metal liner into a hypersonic 'superplastic' slug (i.e. it's still solid.) The penetration mechanic here is strictly a function of velocity, and only works as long as the jet is solid. A shaped-charge round does not rely on thermal effects for penetration at all. A plasma is simply a hot, ionized, gas. Shooting your enemy with it would simply result in surface burns.

[Purple]

So, if I gather what you've read correctly, you simply want to make a shaped-charge round sound cool by tacking the word "plasma" in front of it.

That was not the real intention. But in hindsight I can see how you wold think that due to my lack of basic knowledge about the operating principals of shaped charges. A fault now thankfully corrected by you. What I am trying to do is create a low tech weapon that does the same job that is usually attributed in SF to plasma weapons. Busting open light armor and power armored infantry.


@Rabid
That is exactly what I was thinking. Or rather, somethign more like the XM25 but scaled up. Thanks for the cool links. Since now I know it can be done the next step is to see how good it would be. Does anyone care to discuss the practicability and effectiveness of such weapons. For example, would they and the munitions be massive and costly. Are my estimates for lower mass and hence recoil correct? Could it be fired on full auto? What kind of effect would it have in close quarters (would the jet scatter if it hit a wall and stuff)? What the effect would be against unarmored infantry (I imagine not nice to them)? etc.

Edit: I just found something today that I think I could use with minimal changes to make it more rifle like and less of a man portable auto canon. http://en.wikipedia.org/wiki/Type_87_grenade_launcher But in essence it would be a 35mm battle rifle and not a grenade launcher, just so we don't get confused.

[GrandMasterTerwynn]

So, if I gather what you've read correctly, you simply want to make a shaped-charge round sound cool by tacking the word "plasma" in front of it.

That was not the real intention. But in hindsight I can see how you wold think that due to my lack of basic knowledge about the operating principals of shaped charges. A fault now thankfully corrected by you. What I am trying to do is create a low tech weapon that does the same job that is usually attributed in SF to plasma weapons. Busting open light armor and power armored infantry.


@Rabid
That is exactly what I was thinking. Or rather, somethign more like the XM25 but scaled up. Thanks for the cool links. Since now I know it can be done the next step is to see how good it would be. Does anyone care to discuss the practicability and effectiveness of such weapons. For example, would they and the munitions be massive and costly. Are my estimates for lower mass and hence recoil correct? Could it be fired on full auto? What kind of effect would it have in close quarters (would the jet scatter if it hit a wall and stuff)? What the effect would be against unarmored infantry (I imagine not nice to them)? etc.

The rounds would be bulky because you need a mass of explosive to form the penetrator, and the round must have a nose long enough to provide the standoff distance necessary for the penetrator to form. They'd be lighter in mass, owing to the fact that explosive isn't as dense as lead, but a large diameter, low mass round tends to feel air resistance more, so the ranges for your grenade autocannon would be much shorter than the same autocannon firing tungsten-tipped solid slugs.

In close-quarters the effects depend on the sensitivity of your fuses and the sturdiness of the walls. Typical sheetrock walls might not set off the rounds, but punching through them would destabilize them, so they'd be tumbling on the other side. If the explosive did go off, the penetrator would zip through the wall, and then fragment (since the jet will quickly stretch to the point where it all just comes apart.) So the overall effect will be like shooting birdshot, which isn't known for its armor defeating properties, although I wouldn't suggest using a grenade autocannon in a hostage rescue situation.

The effect on unarmored infantry would be about what you'd expect to get by shooting them with 35mm explosive rounds.

[Purple]

The rounds would be bulky because you need a mass of explosive to form the penetrator, and the round must have a nose long enough to provide the standoff distance necessary for the penetrator to form. They'd be lighter in mass, owing to the fact that explosive isn't as dense as lead, but a large diameter, low mass round tends to feel air resistance more, so the ranges for your grenade autocannon would be much shorter than the same autocannon firing tungsten-tipped solid slugs.

How long are we talking about? Would something like the soviet 30x165mm round do? Also, how would I cure the range problem? Could I add more propellant or perhaps fin stabilized rounds? Or is that just taking things way over the top and into magic territory.

Also, could the long tip be replaced by some sort of laser sensor that detonates the round at a certain range from a surface?

[Imperial528]

I am definitively looking to avoid any sort of magnetically contained plasma blobs. That is both a cliché that has been overused way too much in SF and is extremely unpractical not to mention horrifically costly for the price of a basic infantry weapon.

Do you mean magnetically contained as in a magical moving magnetic field that holds the plasma together, or an actual moving electromagnet that holds the plasma together?

Since I use the latter in an RPG, and I think you know which RPG I am talking about.

[Sea Skimmer]

The rounds would be bulky because you need a mass of explosive to form the penetrator, and the round must have a nose long enough to provide the standoff distance necessary for the penetrator to form. They'd be lighter in mass, owing to the fact that explosive isn't as dense as lead, but a large diameter, low mass round tends to feel air resistance more, so the ranges for your grenade autocannon would be much shorter than the same autocannon firing tungsten-tipped solid slugs.

XM25 is already intended to have a shaped charge shell once its in wider service. The standoff required for small shaped charges is very slight and provided by the existing windscreen on the projectile.

[Simon_Jester]

For purposes of soft-SF, I've imagined "plasma cannon" that are basically just mass drivers which fire with homicidal indifference to whether the projectile gets vaporized on its way out the barrel. If it gets the shot going faster, and the range is short enough, this could actually be worth it.

It helps if you have an anisotropic temperature, mind- the transverse temperature is what's going to determine the rate at which your 'slug' spreads out and becomes ineffective, while the longitudinal temperature is relatively less important... but apt to be much much higher.

Note that this really only makes sense in the context of soft-SF with ridiculous accelerations and so on; it's not pure bullshit but it's not something I'd put in a setting I wanted to call 'hard SF.'

[Purple]

Do you mean magnetically contained as in a magical moving magnetic field that holds the plasma together, or an actual moving electromagnet that holds the plasma together?

Since I use the latter in an RPG, and I think you know which RPG I am talking about.

Either. The whole concept of having a power generator and a lot of moving parts inside a projectile just does not strike me as plausible let allone practical. And definitively not on the infantry level. There are just too many points of failure to rack up costs and make it unreliable.

@S_J
Thanks for the input but I am definitively trying to go hard here rather than soft. That kind of mass driver would have issues with the barrel getting destroyed as well.

@Sea Skimmer
Really? That is cool. Just what I need. (looking it up)

[Starglider]

or an actual moving electromagnet that holds the plasma together?

The whole concept of having a power generator and a lot of moving parts inside a projectile just does not strike me as plausible let allone practical.

Why do you need a power generator? The thing only has to be powered for fractions of a second. With (very) high temperature superconductors, a decent circulating current will work fine. Actually I'm not sure you even need superconductors, hysterisis in a high inductance coil should retain a decent field for the milliseconds it takes to go from the gun to the target, not sure if a useful working pressure is possible with realistic materials though. Regardless, the basic problem is that there's no plausible man-portable plasma generator that has a better firepower/weight and firepower/cost ratio than just handing out grenade launchers.

[Imperial528]

I always thought capacitors would be a good way to do it, since the short time it takes the bullet to reach the target shouldn't exceed the time it takes to release the energy. You really only start to need power storage when you use this for long-range projectiles, like those in space, or artillery, but even then you can fit it with a few batteries and you're all set so long as they can power it.

As for the cost of it, I consider plasma bullets to be either heavy infantry or specialist equipment. The basic GI doesn't need a large plasma rifle, since he should really only be expected to take out other GIs and light vehicles or entrenched infantry, so his main armament should be a conventional rifle and the right grenades. The soldier with a massive suit of power armor, on the other hand, is expected to dish out more than he can take, or at least as much. Even if you can't fit the system on power armor economically, there's no reason you couldn't put it on a tank or APC.

[Simon_Jester]

@S_J
Thanks for the input but I am definitively trying to go hard here rather than soft. That kind of mass driver would have issues with the barrel getting destroyed as well.

It's that side of the equation that makes this soft-SF: the barrel wear issue is tremendous and requires a very advanced engineering approach, relying heavily on bullshittium-phlebotinum alloy and the use of powerful Handwave-Smith fields.

[Sarevok]

Why would we use plasma as anti-armor weapon ? Plasma can be accelerated to immense speeds. It would be much more effective to use plasma weapons for short range point defense.

[Starglider]

Plasma can be accelerated to immense speeds.

This is called a neutral particle beam.

[[R_H]]

@Rabid
That is exactly what I was thinking. Or rather, somethign more like the XM25 but scaled up. Thanks for the cool links. Since now I know it can be done the next step is to see how good it would be. Does anyone care to discuss the practicability and effectiveness of such weapons. For example, would they and the munitions be massive and costly. Are my estimates for lower mass and hence recoil correct? Could it be fired on full auto? What kind of effect would it have in close quarters (would the jet scatter if it hit a wall and stuff)? What the effect would be against unarmored infantry (I imagine not nice to them)? etc.

Perceived recoil isn't just dependant on the mass of a munition. Weapon mass, projectile velocity, even the type of action affect recoil and how it is perceived. The manportable automatic grenade launchers use quite low capacity magazines, between 4 and 8 rounds. The mass of the ammunition may not be as much of a problem for a power armoured individual, but there's still the size that could be problematic (especially when using drums). Magazine dimensions will have an effect on how easily the weapons can be used from various fighting positions.

To illustrate my point, those Saiga 12s pictured below are about 1m long, that's a single stack magazine with a capacity of ten rounds. Firing from prone would be quite challenging.

How long are we talking about? Would something like the soviet 30x165mm round do? Also, how would I cure the range problem? Could I add more propellant or perhaps fin stabilized rounds? Or is that just taking things way over the top and into magic territory.

Also, could the long tip be replaced by some sort of laser sensor that detonates the round at a certain range from a surface?

That's autocannon ammunition, that'd have to be some pretty advanced/capable power armour.

How much range is needed? Adding more propellant will, all other things remaining constant, increase (perceived) recoil. This could mean that your power armour wearers needed more time to reaim between shots.

What about ammunition along the lines of the Raufoss Mk 211 (high explosive, incendiary with an armour-piercing penetrator)?

[Simon_Jester]

Yes. A particle beam can be treated as a subset of a plasma, with high average velocity in one direction, relative to the velocity of particles perpendicular to the beam's line of flight. Typical particle beams are single-species: all electrons or all protons or all a single type of ion, though, whereas most other plasmas consist of multiple species (say, electrons and hydrogen ions).

When dealing with neutral beams, though, the distinction between "plasma" and "particle beam" becomes... not academic, not even academic because in the academic context it's the same damn thing either way. No, it becomes moot.

So I say let people call it whatever they like.

[Eulogy]

Plasma weapons would work as the following:
1) Some sort of frag grenade, since gas does expand rapidly and plasma by definition is hot, speeding up the gas
2) A VERY short ranged blowtorch, basically a fire knife
3) Chemical warfare, where the poison can remain potent even while it is plasma

A flash is literally how long plasma lasts out of its containment. Weapon designs will have to use that to its advantage. Naturally, this means that plasma flamethrowers and pewpews shouldn't exist in any series with anything resembling hard science.

[Sea Skimmer]

The idea of a grenade or a bomb being filled with super hot high pressure plasma… does not really work in any practical sense. The plasma has to be generated at the time of use, since you sure aren’t going to be able to reasonably fill up a tank with the stuff and go fly a bombing raid with it hanging under your wing! That’s kind of begging for a disaster the moment one of the canisters leaks. A super hot grenade or artillery shell meanwhile, well that also has some obvious problems regarding transport and use and even just having the warhead in a weapon barrel. Plasma can be generated on demand from certain explosions, but at this point the plasma becomes a clearly secondary effect since that explosion is going to be pretty serious. Even if you could carry around hot plasma in a warhead, it’d be a low density filler by nature and almost certainly less effective then a nice solid metal based reactive material explosive at applying heat to the target.

I have seen one very interesting idea, which has been tested, for use for plasma in weapons; that of a shaped charge generated plasma antenna. This would be used to help conduct the effects of a destructive EMP warhead onto a target making its effects more directional and more intensive. The plasma also potentially could help conduct the heat of the explosion onto the target more effectively. But this is all secondary effects. Plasma also could have value in defensive tasks, the infamous Russian radar stealth idea for example, and certain plasmas should be effective at scattering laser beam.

How would a plasma chemical weapon work or make sense BTW? If the plasma is hot it will quickly rise above ground level and blow away with the wind rather then sticking around at ground level to kill people. Meanwhile if the plasma is thousands of degrees, if it somehow did stick around at ground level it should just burn people to death on contact anyway. No need for poison!

[Rabid]

How would a plasma chemical weapon work or make sense BTW? If the plasma is hot it will quickly rise above ground level and blow away with the wind rather then sticking around at ground level to kill people. Meanwhile if the plasma is thousands of degrees, if it somehow did stick around at ground level it should just burn people to death on contact anyway. No need for poison!

Plus, plasma mean "atom nuclei separated from their electrons". That means that all molecules are cracked, reduced to their composing elements. How exactly do you intend to make a poison if you can't make molecules ?...

[Swindle1984]

In a couple of the Man-Kzin Wars short stories, plasma guns are mentioned; they're used as fancy flamethrowers, and at short range can burn through obstacles like a blowtorch. Most Kzinti became leery of using them in enclosed areas (where they'd be most effective) due to the risk of setting yourself on fire; most models have a built-in fire extinguisher, allowing soldiers to hose objects (or people) down with fire retardant in case of an accident or enemy action.

They're mainly used to clear out the caves of human resistance fighters and morlocks on Wunderland.

Then again, this is the same setting which has "strakakkers", which fire teflon-and-glass beads and basically sand-blast the flesh off of people.

[Swindle1984]

How would a plasma chemical weapon work or make sense BTW? If the plasma is hot it will quickly rise above ground level and blow away with the wind rather then sticking around at ground level to kill people. Meanwhile if the plasma is thousands of degrees, if it somehow did stick around at ground level it should just burn people to death on contact anyway. No need for poison!

Plus, plasma mean "atom nuclei separated from their electrons". That means that all molecules are cracked, reduced to their composing elements. How exactly do you intend to make a poison if you can't make molecules ?...

I think he's saying plasma that remained at ground level and burned people would render chemical weapons unnecessary. But the idea is stupid. Plasma is NOT a persistent chemical that sticks around and continues burning shit as if you doused it in napalm.

[Purple]

How would a plasma chemical weapon work or make sense BTW? If the plasma is hot it will quickly rise above ground level and blow away with the wind rather then sticking around at ground level to kill people. Meanwhile if the plasma is thousands of degrees, if it somehow did stick around at ground level it should just burn people to death on contact anyway. No need for poison!

Plus, plasma mean "atom nuclei separated from their electrons". That means that all molecules are cracked, reduced to their composing elements. How exactly do you intend to make a poison if you can't make molecules ?...

I think he's saying plasma that remained at ground level and burned people would render chemical weapons unnecessary. But the idea is stupid. Plasma is NOT a persistent chemical that sticks around and continues burning shit as if you doused it in napalm.

Unless you deploy it in an enclosed space, like the corridors of a starship. Close the blast doors to isolate the boarding team and hose the whole section with plasma.