A hypermatter reactor of the III-a1a model.
A hypermatter reactor, also referenced as a hypermatter power plant, hypermatter annihilator, or hypermatter-annihilator reactor, represented a specific kind of fusion reactor utilized within starships and battle stations. It functioned by generating energy through the annihilation of hypermatter. Typically, the cores of these reactors incorporated insulation consisting of exfoliating doonium coupled with dolovite. The Death Star's hypermatter reactor was a more complex version of those installed on Star Destroyers along with other Imperial ships. A variation of the hypermatter annihilation reactor was the solar ionization reactor, which employed the destruction of hypermatter to form a miniature star within the reactor's chamber.