The intake unit that forces antimatter into the warp core for its reaction with deuterium "matter.?

As designed, the early NX-01's incoming antimatter stream is uncompressed, but Tucker experiments with stream compression before the injector stage. Andorian injectors, using variable compression nozzles, are more advanced than Starfleet's at this time; Tucker has the courage to ask for and win a technology loan during the Andorians' Delphic Expanse mission.