I'm an aerospace engineering student, currently doing an erasmus in Pisa, Italy. I was thinking about the Hall Effect Thrusters and how they are able to produce thrust. There's something that I don't understand, when the hollow cathodes emits electrons to neutrilize the flow at the exit, there are some electrons going back to the exit of the channel. On the other hand, there are some electrons trapped in the magnetic field (radial direction) along the channel and it works as a magnetic resistance. Do you know if there's an accumulation of electrons in time in the magnetic field? If yes, can appear problems when ionizing the fluid? Thanks in advance.