Plasma is a relatively common weapon in science fiction, with weapons that fire magnetically-bound superheated plasma or melee weapons that hold plasma in a containment field to burn through just about anything.

Plasma in real life isn't as useful as a weapon. It loses heat quickly when fired (assuming we find a way to keep the plasma from just expanding into hot air long before it reaches the target) or is almost as deadly to the wielder of a plasma melee weapon as to it's target. So my question is: assuming technical problems can be overcome, what would be the most efficient way to use plasma as a weapon?

My own thoughts so far:

  • "classic" plasma fired from a gun held by some pseudo-magic magnetic core. Even when keeping it together like this it'll lose a lot of heat while traveling. Perhaps if you managed to increase the magnetic force and make the plasma bolt incredibly tiny you could alleviate some of this.

  • Contained plasma. The plasma is put in an insulation shell to prevent as much heat loss during travel. Upon contact the shell breaks and unleashes the plasma on the target. Potentially you could pressurize the plasma in the shell, upon breaking the plasma would burst forth from the hole similar to a shaped charge, although I'm not sure how much plasma would spray into/on the target and how much would just propel the shell and plasma away from what it hit. Probably the best bet would be to pressurize it only a bit so the plasma jet upon shattering wont exceed the speed with which it impacts a target.

  • melee weapons with plasma-contained edges. The "classical" form where most of the blade is a containmentfield with a lot of plasma in seems too dangerous for the wielder and very energy inefficiënt. A better way would likely be to have a "normal" melee weapon where its edges are formed by a containment field and plasma. The thinness, heat and how this plasma edge reforms after each strike would be the key here without requiring so much heat to cut something that striking an enemy would cause a water vapour explosion and heated gasses to burn the wielder.

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    $\begingroup$ I wonder what would happen to this question if one were to replace the word "plasma" with "hot gas". I also wonder if the querent truly understands the difference between plasma and hot gas -- the actual differences between plasma and hot gas are not really conducive to more deadly effects. $\endgroup$
    – AlexP
    Mar 23 '19 at 12:35
  • $\begingroup$ @AlexP I think you mean "replace with superheated gas", which is what most forms of plasma that you can weaponize would be. The point is that science fiction has a lot of plasma weaponry but I would like to know the ideal way you could use it as a weapon. $\endgroup$
    – Demigan
    Mar 23 '19 at 13:18
  • $\begingroup$ The use as Weapon of Massive destruction is a really reasonable use case. For more about it the post in Physis SE What would happen if 63 TJ in form of superheated plasma would released abrutly? can help. $\endgroup$ Oct 27 at 0:18
  • $\begingroup$ @ErdelvonMises - that's only really the case if you already have 63TJ of plasma. If you're using that much energy, there are much more efficient ways to destroy things with it. $\endgroup$
    – jdunlop
    Oct 27 at 0:58
  • $\begingroup$ @jdunlop As what? $\endgroup$ Oct 27 at 1:00


Nukes are probably the best answer for half the questions in this site.

From the wiki:

Initially, the fireball contains a highly ionized plasma consisting only of atoms of the weapon (...)

But that's probably not what you were expecting, so let's try an alternative.

Weaponized Particle Accelerator

You can use a particle accelerator such as the LHC to accelerate plasma. Then you let some escape. A few particles going off a tangent will be energetic like cosmic rays.

A russian scientist was victim to such a thing once, taking a headshot from a particle accelerator. Since our universe is boring and lacks element Narrativium, he did not get any superpowers. He got half of his face paralyzed, tinnitus and deafness in a ear and frequent convulsions.

Anyway, since particle accelerators are hard to move and to aim, you wouldn't be able to use this in battle. But you could use it as a very expensive trap, or an instrument to apply death penalties.


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