Matter-Antimatter Reaction Assembly

A Matter-Antimatter Reaction Assembly (often known simply as an M/ARA) is a type of energy reactor which is fueled by injectors of matter and antimatter into a central reaction element, creating large amounts of energy when those two materials mutually annihilate each other. Matter and antimatter is injected into the M/ARA in an intermix 1:1 ratio. (TNG: "Coming of Age") The dilithium crystal is used to moderate this reaction.

The Dilithium Articulation Frame is housed inside the M/ARA, (TNG: "Skin of Evil") behind the Dilithium Chamber Hatch. (TNG: "The Drumhead")

The prototype Jem'Hadar battleship had a fatal design flaw; the braces holding together the ship's M/ARA were vulnerable to a specific type of radiation. The crew of the USS Valiant believed they could use this flaw to their advantage when they were plotting the ship's destruction in 2374. (DS9: "Valiant")

On Federation starships, this type of reactor is often used as a Warp Core, powering the warp drive. The most common version of this system is fueled by slush or liquified Deuterium, and its Antimatter counterpart, anti-deuterium. These elements are funneled through Magnetic Constrictors and combined within a Dilithium Crystal to create a stream of highly energized Electro-plasma which is routed to the Warp Coils within the vessel's nacelles, creating a warp field. (Star Trek: The Next Generation Technical Manual)