I'm writing a short story and I'm intending to have one of the characters utilizing a plasma weapon as infantry. The way I'm planning on explaining it is the plasma is kept in a slightly unstable magnetic field and the weapon is powered by a large shielded capacitor while wearing a suit of highly heat resistant body armour. With the potential for some kind of shield technology for added heat resistance, could it be viable?
Edit: I mean the capacitor is shielded by normal armour plating since there's no real difference between a battery and a bomb, and frankly it would be expensive if it was damaged and released it's energy more explosively.
In regards to the magnetic field it's intended to be generated on demand, using atmospheric gas or a reinforced tank.