At the SGC, Dr. Jay Felger and his research assistant, Chloe, had developed a prototype plasma weapon intended to replace the missiles on the Prometheus. The energy-based weapon was designed to fire a focused plasma pulse, similar to a photon torpedo, however during its initial test at the SGC lab, the weapon caused an overload and a power failure that nearly cost Felger his job.
A more successful version of a plasma cannon weapon, the X-699, was later developed by Carter and Dr. Lee.
Cross Reference: Chloe, Jay Felger, X-699
Episode Reference: Avenger 2.0