Plasma cannon
From Lexicanum
The plasma cannon or heavy plasma gun is a plasma weapon, a larger version of the plasma gun. Due to its size and sheer power requirements, plasma cannon tend to be found mainly on vehicles, but Space Marines are known to use them in their Devastator Squads. Some gangs in the Necromunda Underhive make use of the plasma cannon; they call the weapon a "sun gun" due to its incinerating effect.1
The gun itself has a similar effect to the plasma gun, except this weapon does damage over a much larger area. Several individuals can be caught in one blast, making the plasma cannon a potent weapon. Unless hooked up to a vehicle's systems, a plasma cannon suffers from the usual overheating problems that plague plasma weapons.
Vehicles that can carry the plasma cannon include the Leman Russ Executioner, Leman Russ Demolisher and Dreadnoughts.
