A Pulse Submunitions Cannon is an advanced and very large Tau Pulse Weapon that utilises pulsed electromagnetic induction fields to propel lethal micro-bursts of plasma over extremely long ranges. A Pulse Submunitions Cannon, similar to the smaller Pulse Submunitions Rifle, is a newly developed form of Pulse Weapon, designed to saturate large areas with plasma pulses at range. Unlike standard Pulse Weapons, these powerful cannons fire clusters of sophisticated micro-submunitions that detonate in close proximity to their target in a storm of separate pulse-discharges, showering a wide area with deadly effect. Larger targets such as bulky infantry, monstrous creatures and vehicles inevitably suffer proportionally greater harm from Pulse Submunitions Cannons, as they can be struck with a wave of near-simultaneous detonations, magnifying the blast and ripping them apart. Pulse Submunitions Cannons have an extreme range and generally are used in a heavy long-range fire support role. Pulse Submunitions Cannons are only wielded in pairs by XV107 R'varna Battlesuits, which can also nova-charge the weapon systems via its Dark Matter Nova Reactor and double their rate of fire.
The Pulse Submunitions Cannon works by electromagnetically accelerating a plasma shell down its barrel. In effect, it is a miniature mass accelerator. On firing, a ferromagnetic, solid slug is chambered from the magazine and turned into plasma by electromagnetic induction, as it would be relatively easy to alternate the coil current at frequencies sufficient enough to heat the coil to an extreme temperature while keeping it in the chamber. The solenoid is then charged fully, propelling the newly produced plasma out of the gun at an extreme velocity while keeping it cohesive. Though this electromagnetic field continues to keep the plasma together until impact, residual plasma is expelled from the barrel to produce the weapon's considerable muzzle flash. Maintenance of the field is also aided by a bolt-like apparatus, which increases the field strength and therefore the range. The weight of the bolt also serves to dampen the recoil from firing. Without the electromagnetic field, the fired plasma would all dissipate at the barrel mouth, producing a weapon with a range of approximately twenty centimetres. As it is, residual energy and waste plasma, together with the heat produced by energizing the coil, necessitates two barrels to avoid overheating.
The power required to generate these immense electromagnetic fields comes from the secondary magazine which is effectively a very powerful and dense rechargeable battery in the weapon's stock. It is changed less frequently than the primary power pack, and can be recharged from the firer's suit or combat armour. Vehicle-mounted Pulse Weapons are usually connected directly to a suitable power source, allowing higher rates of fire with sufficient heat dispersal and eliminating the secondary magazine. Pulse Weapon rounds do a great deal of damage on impact, mostly due to the extreme thermal energy of the plasma mass and the speed with which the projectile impacts, which helps ensure that armoured targets are more heavily damaged. The electromagnetic field that holds the charge together flattens on impact slightly before breaking, which causes the resulting impact to spread over a wider area than would otherwise be possible. The speed at which the plasma projectile is launched is so extreme, that in some cases, it has been known to "light the air on fire".
- Codex: Tau (3rd Edition), pg. 19
- Codex: Tau Empire (4th Edition), pg. 29
- Codex: Tau Empire (6th Edition), pp. 66-67
- Imperial Armour Volume Three - The Taros Campaign, pp. 80-81
- Rogue Trader: Into the Storm (RPG), pg. 121
- Deathwatch: Core Rulebook (RPG), pg. 366
- Forge World – XV107 R'varna Battlesuit Experimental Rules Datasheet