I allays imagined engines to be very different from the ones operating in normal space, so nothing like a thruster at all.
Since they don't seem to convey any sort of G force on ships and they have no acceleration they operate on a very different level. I always imagined them acting more like an Alcubierre drive type of principle and interacting with the ether in a way that is hard to describe in scientific terms.
The names of the drives could be very different and definitely have more of Trans Newtonian theme... they certainly are not going to operate with Anti-matter, or Ion, Fusion or the like as they use Sorium fuel and the engine itself is something completely different.