Deuterium injector

A deuterium injector is a component installed in the warp core of a starship.

Shortly after Lieutenant Lee Kelso transferred aboard the USS Enterprise from the USS Potemkin, Lieutenant Commander Montgomery Scott caught Kelso making slight adjustments to the injectors. While Kelso was trained as a helmsman, he also had vast amounts of engineering knowledge, which sparked a friendly rivalry with Commander Scott. (TOS novel: My Brother's Keeper: "Constitution").

In 2372 in the mirror universe, Captain Benjamin Sisko had to take the Defiant's injectors offline and restart them, as part of his forced maintenance on the Defiant. (DS9 episode: "Shattered Mirror").