X-699 plasma cannon
From The Stargate Omnipedia
Plasma weapon of human engineering, similar design -- perhaps based on -- Dr. Jay Felger's plasma weapon. The cannon is powered by a miniature naquadah generator situated on top of the main housing. It is large enough that it must be held and fired in two hands.
Energy settings are not known, but the cannon is at least capable of stunning its targets, rendering them unconscious.
KEY EPISODES
Bounty - Carter is forced to use the X-699 during an exhibit at Applied Technologies when a bounty hunter attempts to take her life.
Stargate: Continuum - Vala tries to take the X-699 to Baal's extraction ceremony as a little added security, but Colonel Mitchell takes it away from her.