afterburner

Second combustion chamber in a turbojet or turbofan engine, immediately in front of the engine's exhaust nozzle. The injection and combustion of extra fuel in this chamber provide additional thrust for takeoff or supersonic flight; in most cases, the afterburner can nearly double the thrust of a turbojet engine. The jet nozzle must be larger when using the afterburner, so an automatic, adjustable nozzle is an essential component of the afterburner system. Because the afterburner sharply increases fuel consumption and is generally less effective at subsonic speeds, its use is usually restricted to supersonic military aircraft.