Matter-antimatter reaction
From Memory Alpha, the free Star Trek reference.
The matter-antimatter reaction is the reaction of matter and anti-matter which results in the most exothermal reaction known.
The primary source of power utilized in Federation starships is provided by the enormous amount of output energy produced by a controlled matter-antimatter reaction. This reaction typically occurs within the intermix chamber of a warp core, and is contained by a magnetic containment field. This reaction produces a considerable amount of heat energy in addition to the kinetic energy that is used by the vessel's propulsion system. This heat is supplanted by a plasma coolant system that is situated adjacent to the intermix chamber. The loss of coolant will inevitably result in the overheating and destruction of the intermix chamber, causing a warp core breach. (Star Trek Generations)
Certain types of matter-antimatter reactions are known to create omicron particles. (DS9: "Shadowplay")
The warp core aboard an Intrepid-class starship is fueled by a matter/ antimatter reaction, capable of producing a maximum output of 4,000 teradynes per second, which provides power for faster-than-light propulsion. (VOY: "Drone") Additionally, the unit of Cochrane is used to measure a matter/antimatter reaction. (VOY: "The Gift")
If the antimatter reaction rate, in a matter-antimatter reaction drops below 9%, it can cause the system's plasma injectors to lock up, which subsequently prevents the nacelles from being initialized. (VOY: "Resistance")
