Elaine Thul
Duchess Thul

Image Source: https://deadanarchistphil.wordpress.com/tag/plasma-cannon/
Intent: To Kill People in Armour
Development Thread: If necessary
Manufacturer: House Thul Estates
Model: H.T.E. Plasma Cannon MkI
Affiliation: House Thuls Housecarls
Modularity: No
Production: Limited Housecarls only
Material: Durasteel,
Classification: Plasma balls
Size: Handheld in power armour, stationary if not
Length: 1.5 meters
Weight: 50 kg
Ammunition Type: Plasma
Ammunition Capacity: 350
Effective Range: 1000 meters
Rate of Fire: Fully-automatic
Special Features:
Strengths: Burns Through Armour
The more hits, the more plasma stays on armour
Weaknesses: Can not hide with one
Requires power armour to use properly
Needs reloading quite quickly if used without firing discipline
Not accurate if running, even in power armour.
Description: The weapon is basically a gatling gun, but it fires mini bolts of plasma via a chain of slugs. These build up on the enemy armour, and will eventually burn through. As it hits an opponent, the plasma would build up and begin burning it way through. The weapon is heavy weapon, especial with ammo pack, and as such it only really usable if in power armour. The plasma burns through armour in a similar way as lightsaber, though a weaker one. Though as the plasma is attached to armour, it will slowly melt through. Though more hits, the quicker the burn through the armour will be. As such it can even penetrate heavy armoured plated tanks and walkers, eventually.
Primary Source: http://starwars.wikia.com/wiki/Plasma_rifle
http://starwars.wikia.com/wiki/Plasma_cannon