Plasma cannons are a form of directed energy cannon weaponry. On Starfleet vessels, they were the precursors to phase cannons. Plasma cannons fired a plasma discharge in the form of a beam or a burst similar to the plasma bullets fired by hand-held plasma weapons, but much bigger in size. (ENT: "Fortunate Son", "Horizon", "Shadows of P'Jem")
History
In the early- to mid-22nd century, Earth Cargo Service freighters were commonly equipped with low-yield turrets, often referred to as "popguns", designed only to break up asteroids and meteors. Earth Y class freighters were typically equipped with a single plasma cannon and J class ships with two turrets. The captains of these freighters, however, would often upgrade the cannons for more powerful ones the first chance they got. To achieve a weapons lock, the target had to be within a nine kilometer range. (ENT: "Fortunate Son", "Horizon")
The Enterprise NX-01 was equipped with several plasma cannons during the first days of its mission, but was eventually upgraded with the more advanced phase cannons. (ENT: "Broken Bow") Enterprise's Shuttlepod 1 was equipped with dual plasma cannons. (ENT: "Awakening") These plasma cannons had a range of less than ten kilometers. (ENT: "Shuttlepod One")
In the mid-22nd century, Nausicaan pirates also utilized fore and aft plasma cannons on their raiders. (ENT: "Fortunate Son")
In an alternate timeline, Vosk, the leader of the Na'kuhl, offered Nazi Germany plasma cannons and plasma rifles in exchange for materials to build a temporal conduit. (ENT: "Storm Front, Part II")
In the mirror universe, in 2155, the Terran Empire still used plasma cannons on NX-class starships. (ENT: "In a Mirror, Darkly", "In a Mirror, Darkly, Part II")
