AT: "at"
The Yellowstone venting tetryon plasma
Tetryon plasma was a variety of warp plasma.
In 2372 in an alternate timeline, Lieutenant Lasca asked Harry Kim to explain a dilithium fracture problem related to the tetryon plasma in the USS Yellowstone's warp nacelles, but Kim didn't know the answer and feigned sickness to get away with his apparent ignorance.
A vessel equipped with normal warp drive could stall out when passing through a cloud of tetryon plasma. (VOY: "Non Sequitur")