Plasma

In physics and chemistry, Plasma is a partially ionized gas, in which a certain proportion of electrons are free rather than being bound to an atom or molecule. The ability of the positive and negative charges to move somewhat independently makes the plasma electrically conductive so that it responds strongly to electromagnetic fields. Plasma therefore has properties quite unlike those of solids, liquids or gases and is considered to be a distinct state of matter. Plasma typically takes the form of neutral gas-like clouds; for example, in the case of stars.

Function
Though difficult to control, the Covenant military and Forerunner Constructs use plasma in a weapon form to great effect, containing and guiding it in the form of a single bolt, beam, or continuous stream. Plasma-based weapons are the most common armament of Covenant infantry and vehicular forces, and are the main armaments of their warships. Smaller weapons are designed to deplete shielding or melt infantry armor, while heavier weapons can destroy vehicles or buildings. The largest are mounted to capital ships, and are used for orbital bombardment and ship-to-ship combat. When a plasma weapon is charging, high quantities of beta particle radiation are emitted. The UNSC uses plasma as an energy source and to cut heavy metals in factories, and attempted to produce it for use in their armed services, but apparently chose to abandon the project, instead falling back on projectile weaponry.

Protection
Complete protection from Plasma is generally hard to obtain due to the Plasma's high damage ratio. Armor used by Marines usually has a good protection from Plasma, but only to an extent. Eventually, the persons armor will be literally melted or burned to uselessness. That's why when a Marine is constantly hit in a certain place numerous times by Plasma, the armor will give way and the person will have severe to life threatening injuries. John 117's armor is much like the Marines, being that it will eventually give way to the Plasma. The added bonus Spartans have is the shield which protects from Plasma.

Starship Weaponry

 * Plasma Torpedo
 * Plasma Turret
 * Plasma Charge

Vehicles

 * Scarab
 * Seraph
 * Banshee
 * Wraith
 * Spectre
 * Phantom
 * Ghost
 * AA Wraith
 * Rhino (Prototype UNSC plasma artillery)

Weapons

 * Automated Plasma Cannon
 * Plasma Mortar
 * Twin Plasma Cannons

Explosives

 * Plasma Grenade

Firearms

 * Energy Sword
 * Plasma Rifle
 * Plasma Pistol
 * Brute Plasma Rifle
 * Fuel Rod Gun

Turrets

 * Shade
 * Plasma Cannon

Trivia

 * Human users can contract Boren's Syndrome from prolonged contact with the radiation emitted by plasma grenades, an example being Sergeant Johnson.
 * For gameplay reasons, plasma is less lethal to unshielded NPCs in the Halo games than in the novels. In the games, Marines can take a barrage from a plasma weapon without being incapacitated, but in the books there are several incidences of plasma easily burning through both armor and flesh. The excuse for this being that it all boils down to game play in the end.
 * It seems that the power of the gun depends on what color the plasma gun is. For example the Plasma Pistol shoots out green plasma but is not very powerful, the Plasma Rifle shoots blue plasma and is more powerful, the Brute Plasma Rifle shoots red plasma which is slightly more powerful than blue plasma, while the forward turret on a Phantom in Halo 3 shoots out purple plasma and is the most powerful. It should be noted that in Halo: Combat Evolved and Halo 2, the Plasma on some of the Plasma Guns can be seen even when Active Camouflage/Invisibility has been activated.
 * If what has been said about the "plasma heirarchy" above is true (and as far as I can tell, it is), then the purple Energy Sword being wielded by an Elite in Second Sunrise Over New Mombassa (a story in the Halo Graphic Novel) should be more powerful than the one used in-game. However, this may simply be due to the fact that Halo 2-era swords (when the story was set) were more purple than blue, so it may simply be an aesthetic difference.

プラズマ