Plasma rifle

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Plasma rifles are theoretical weapons often used in science fiction. They are, in effect, a type of raygun. Plasma weapons use a small nuclear reactor or fuel cell or other type of advanced energy storage device to power an electromagnetic accelerator that fires a stream, pulse or toroid of plasma (i.e. very hot, very energetic excited matter).

As well as rifles, several science fiction universes also contain pistol-size or cannon-size plasma-firing weapons.

The primary damage mechanism of these fictional weapons is usually primarily thermal transfer; it typically causes serious burns, and often immediate death, on living creatures, and melts or evaporates other materials. In certain fiction, plasma weapons may also have a significant kinetic energy component, that is to say the ionized material is projected with sufficient momentum to cause some secondary impact damage in addition to causing high thermal damage.

[edit] Similar devices

Currently, there are several tools that are somewhat related to fictional plasma rifles:

[edit] Practicality of plasma rifles

At present, plasma rifles are merely theoretical, as currently they need more power than any handheld device could supply. If small portable fusion reactors are made (an extremely unlikely possibility in the near future), one potential source of weapons-grade plasma sources might be a direct tap on a fusion reactor, especially a dense plasma focus, since the natural yield of such a reactor is a hot high-speed plasma beam. Making real plasma weapons will need a major scientific breakthrough, as the concept of plasma-firing weapons is scientifically difficult, for various reasons:

  • The technology to create plasma toroids and particle beams is presently far too bulky for anything man-portable. In such a high-performance design, the plasma would have to be stored and created in highly focused magnetic bottles, such as those used in NASA's VASIMR rocket: this design has been suggested as a potential weapon design for future real human-engineered plasma weapons. For simpler designs based on plasma cutting torches, a designer might be able to heat the plasma with an arcjet, if his power source is strong enough.
  • Using current technology, if a plasma beam was fired in a planetary atmosphere, it would quickly be stopped by atmospheric resistance and would make a short hot flame like a blowtorch.
  • The plasma shot out of a plasma rifle would tend to dissipate in the surrounding environment within about 50 centimeters from the gun, from thermal and/or electric pressure expansion, called blooming, unless:
    • The magnetic confinement bottle is extended all the way to the target (as it was in the games Halo: Combat Evolved, Halo 2 and Halo 3). Modifications to this bottle could make the plasma home in on its target.
    • The plasma is somehow made self-sustaining over a much longer time period (as with ball lightning).
    • The particles are fired fast enough to reach a target before blooming occurs. This is then a particle beam more than a plasma shot (at least as much as any technical definition for such weapons exists). This would work for use outside atmosphere (i.e. in a space vacuum), but within an atmosphere would merely cause a hotter short flame from more violent collision between the flying particles and the atmosphere.
    • It might also be possible to generate a laser beam "tunnel". High-energy lasers ionize the air around the beam, heating the atmosphere and providing the plasma bolt with an easy passage to the target (see electrolaser).
    • Another laser-assisted plasma weapon approach for use in atmosphere is possible if the laser is powerful enough to blast the air out of the way, but having the plasma particles reach the target before the newly-created vacuum channel collapses in on itself is a problem unless the weapon possesses sufficient power to either sustain the channel or the aforementioned "plasma particle beam" approach is used.
  • One common characteristic of plasma weaponry is its tendency to overheat, thus being sometimes impractical even within the context of science fiction. Two of the more well-known examples include the vulnerable cooling times for the plasma weapons in the Halo series, or the venting of built-up heat from powerful but unstable plasma weapons (capable of serously injuring or killing its user) designed by the Imperium of Man in the Warhammer 40,000 universe.

With a railgun a 'plasma/particle thrower' similar to a long range natural gas flamethrower could possibly be made. Most railguns throw a trail of plasma (of the rail material and projectile material) out after or with the projectile: this is very short lived but extends over 3 to 30 feet. This is because of arcing of the rails and projectile. The plasma conducts and so is subject to the working force of all railguns (Lorentz force). The plasma thrower would use a rapid-fire small projectile and very thick rails spring/actuator mounted that move inwards with wear. A tungsten-aluminium-chromium alloy for both the rails and projectile would yield good results but the projectiles would have to be very small so they are fully disintegrated into the plasma.[citation needed]

But see Shiva Star for an attempt to make a real plasma-firing space weapon.

[edit] Fiction that includes plasma rifles & plasma cannons

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