Plasma injector
From Memory Alpha, the free Star Trek reference.
A plasma injector is a component of a starship's warp drive system, the EPS, which propels drive plasma into the warp coils. (DS9: "Captive Pursuit")
The Enterprise NX-01 operated five plasma injectors. When the fifth one started to fail in 2152, the Enterprise acquired one replacement and two spares from the Kreetassans after a lengthy negotiation process, although the ship could have continued normal operation with only four working injectors. (ENT: "A Night in Sickbay")
Later that year, Rianna Mayweather aligned the plasma injectors of the ECS Horizon. (ENT: "Horizon")
In 2154, an Illyrian captain offered the damaged Enterprise a few plasma injectors or some antimatter, but not a needed warp coil. (ENT: "Damage")
In 2370, the unannounced failure of a plasma injector aboard the USS Rio Grande led to an accident inside the Bajoran wormhole, propelling the runabout into the mirror universe. (DS9: "Crossover")
In 2373, Chief Miles O'Brien was unable to bring the thrusters of a crashed Jem'Hadar warship online due to the ion flow regulator being damaged. (DS9: "The Ship")
The same year, Tieran occupying Kes body remodulated the plasma injector of his shuttle to suppress its warp signature. (VOY: "Warlord")
A little later, an attack by the Nerada took the plasma injectors of the USS Voyager off-line so the ship couldn't engage warp drive. (VOY: "Favorite Son")
By 2375, The Doctor had a holographic image of B'Elanna Torres' foot stuck in a plasma injector. (VOY: "Nothing Human")
In 2376, a Borg cube damaged the Delta Flyer's plasma injectors so the warp drive couldn't be engaged, despite Harry Kim's attempts to clear the injectors. (VOY: "Collective")
