Plasma cannons, Particle guns and Gauss rifles.

There are many weapons featured in science fiction other than the lasers that are beginning to get phased out as they become less “cool”. This article looks at some of the other commonly used options.

Plasma:


Plasma is the fourth state of matter, similar to gas and both extremely hot and ionized. The “plasma cannon/rifle” is a prevalent ranged energy weapon in sci-fi that throws either “bolts” or continuous streams of plasma that burn holes in enemies if not vaporize them entirely, unfortunately they have a tendency to overheat and explode.
Theoretically this could be done, we currently use plasma cutters to cut sheets of metal, but the jet extends less than a foot from the projector limiting its use as a weapon. We can see that there are some problems to work out.


With current technology air resistance stops the stream and makes a short blowtorch like flame. And even without air resistance (for example in vacuum) the plasma would dissipate into the surrounding environment within 50 centimeters of the aperture from thermal and/or electrical pressure expansion (blooming). This could be prevented by extending the magnetic bottle all the way to the target (nigh impossible), firing the plasma fast enough that blooming doesn’t occur (actually a particle beam), or using high-energy lasers to ionize the air around the stream (would only work in atmosphere).
Particle Beams:
Particle beams are streams of subatomic particles accelerated to near-light speed, striking the target’s atoms like billiard balls with a lot more kinetic energy. Aside from the problem of how large modern particle accelerators are…


…they would suffer from the same atmospheric resistance problems as plasma weapons and would most likely only be useable in space.
Electromagnetically Accelerated Projectiles:



Railguns and gauss/coilguns are similar to ordinary chemically propelled guns in that they launch a piece of metal at the target at high speeds. The difference is that instead of an explosion the projectile is propelled by electromagnetic forces and could potentially reach much greater speeds. These are becoming popular due to the fact that the military is actually testing them…

…and you can make your own from spare parts.

The only problems are that with current technology a handheld model takes a long time to build up a charge, what energy they do deliver is much less than a chemically propelled handgun and the navy’s experimental railguns intended for shipboard use tend to generate a plume of plasma from friction that wears out the barrel after only one or two shots.