Single particle simulations of electron transport in the near-field of Hall thrusters

Abstract

The results of 3D, single particle electron trajectory calculations are presented for the near-field of a laboratory E × B Hall plasma thruster. For a prescribed static magnetic and electric field distribution, single electrons are launched and tracked from a simulated cathode. Collisions with external thruster surfaces are accounted for; however, field fluctuations are disregarded. Bulk statistics including the channel to beam electron current ratio, electron lifetimes and spatial distributions of the number density, mean energy, energy distributions, velocity distributions and velocity component ratios are catalogued. For conditions typical of a moderate power Hall thruster, the mean lifetime of electrons in the domain of axial scale length, L = 0.3 m, is approximately 120 ns. Electrons which eventually enter the channel are found to strike the thruster ∼103 times as frequently as electrons which exit the domain in the plume. For the static E and B field distributions used in this study, the channel to beam current ratio is found to be on the order of 0.1 and the velocity ratio, VE/VE×B, over the channel has a mean of ∼0.5, with higher values driven largely by collisions with the thruster indicating the importance of such events in driving transport into the channel.