It does eject mass just like any other thruster. It is just a lot less mass ejected at a lot higher velocity which is why the efficiency is higher. https://en.

It does eject mass just like any other thruster. It is just a lot less mass ejected at a lot higher velocity which is why the efficiency is higher. https://en.wikipedia.org/wiki/Hall-effect_thruster https://en.wikipedia.org/wiki/Hall-effect_thruster