A phase cannon was a phase-modulated directed energy cannon weapon, a type of particle weapon which served as successor to Plasma Cannons and as precursor to the phaser of the twenty-third and twenty-fourth centuries. The prototypes of ship-mounted phase cannons were first introduced by Starfleet in the mid twenty-second century, designed as the primary defense of NX-class starships and serving as supplement for the spatial torpedoes of the time.
Designed as a starship-based version of the hand-held phase pistol, the phase cannon was rated for a maximum power output of five hundred gigajoules. The cannons of NX-class starships were mounted on retractable turrets which extended from the ship's hull when deployed and rotated as they were being targeted. Like phase pistols, phase cannons emitted a concentrated beam of energy that could be set at different yields.
Aboard an NX-class vessel, the assembly was located on F Deck and could be accessed through a hatch within the armory. Instead of drawing power from the EPS grid as they were designed, armory officer Lieutenant Malcolm Reed of the Enterprise NX-01 tied the turret relays directly into the impulse engines to increase their yield by eighty percent. Inverters were installed to cut in at the first sign of an overload. These cannon assemblies were equipped with multiphasic emitters.
Phase cannons were generally more powerful than spatial torpedoes and were therefore more effective in a firefight. Initially, Enterprise's phase cannons could not be fired while the vessel was at warp as doing so would cause the weapon's particle discharge to destabilize the ship's warp field. This, in turn, would result in serious damage to both of the ship's warp nacelles and could possibly even destroy them. By 2152, Enterprise armory officer Lieutenant Reed had corrected this problem. Early phase cannons also took some time to charge when manually activated. This issue was resolved with the implimentation of Reed's tactical alert, which brought the weapons online automatically after the alert was given.
Despite their power, phase cannons were sometimes unable to penetrate the defenses of other alien vessels. Not only did they prove relatively powerless against the shields of the first vessel they were used against, but it would have also taken a sustained beam to punch through the hull of a D5-class battle cruiser. Likewise, the cannons could be easily taken out with a single photon torpedo shot from a Klingon bird-of-prey.
Pulsed Phase Cannons
Pulsed phase cannons were a type of phase-modulated directed energy cannon weapon Starfleet had developed by 2154 based on the experiences of the Enterprise NX-01. At the recommendation of Captain Jonathan Archer, Starfleet began employing this improved version of previous phase cannon technology aboard starships. The first vessel to incorporate pulsed phase cannons was the Columbia NX-02.