Hybrid Monte Carlo particle-in-cell simulation of an ion thruster plume

A numerical code is described that simulates the plumes of ion thrusters an d Hall current thrusters. In the present study, computed flowfield results are compared with existing experimental measurements for the UK-10 ion thru ster. The experimental measurements consist of ion flux, ion density, and B oating potential data. The numerical code combines the direct simulation Mo nte Carlo method for modeling collisions with the particle in-cell method f or modeling plasma dynamics. Xenon neutrals and ions are modeled directly. Electrons are described by the Boltzmann relation. The effect of a finite b ack pressure experienced in laboratory experiments is included. Agreement b etween simulation and experiment is satisfactory. The simulation results ar e found to be very sensitive to input conditions assumed at the thruster ex it plane. In particular, there is uncertainty in specifying the effects of the curvature of the dished grids of the UK 10 thruster on the ion exit vel ocity profile. The sensitivity of the simulations to certain model paramete rs is also examined. These include the cross section for charge exchange re actions, the mechanics of charge-exchange reactions, and the electron tempe rature. The beam ions are found to be only moderately dependent on these va riations, whereas the charge-exchange ions are sensitive to them.