Phase cannon

Aft phase cannon on the NX-01

Phase cannons are beam weapons used on Earth starships in the 22nd century. They are essentially low-performance phasers.

When first installed, they were rated for a maximum output of 500 GJ per cannon; the time period over which this energy would be released was not specified, nor was the delay between shots of this yield. When overloaded, they could produce 5000 GJ bursts, and the ability to produce such bursts was incorporated into their design to improve the ship's offensive capability.

The following year, Lieutenant Reed, the ship's Security officer, tells his Vissian counterpart that the maximum output is 80 gigajoules, but it was clear in the episode that he did not trust the Vissians, and may likely have been giving her false information.

Klingons of the time regarded phase cannons as only minor threats.