First off, I want to apologize if this thread is in the wrong place but I am new this. Anyway, so I recently checked on the VASIMR plasma engine since I was interested in it. But one thing I didn't understand about it is if it ejects the neutral gas it uses. What I mean is that it obviously needs a neutral gas to work but does it eject it out of the thruster or can it be used "infinitely" (I mean for a long time not literally). In the case where it does eject it out the back is it possible for air to be inserted, have the neutral gases secluded and then use them for continuing the thrust?