Gyrokinetic simulations of a Hall thruster drift instability in one dimension using a PIC δf description.

It has been determined that in Hall thrusters there is anomalous transport due to turbulence which limits the effective thrust for a given input power. The turbulence due to the drift waves that arise from the pressure gradients in the main chamber. The most appropriate way to study the stability of drift waves is with gyrokinetic (GK) theory since it captures the relevant small scales present in the plasma. Here we present a study based on a kinetic theory in one dimension where the ions are described with a drift kinetic equation while a GK model is used for the electrons. This is appropriate because of the large ion gyroradius compared to the chamber dimensions. A dispersion relation is obtained which is used to determine the stability on drift waves in the different regions of the thruster. Then, δf kinetic PIC simulations are performed in order to corroborate the analytical results in the linear regime. The nonlinear simulations produce saturated sates that allow to compute the anomalous transport coefficients. The plasma temperature and density profiles are taken from the SPT-100 model data. Even though they are expected to be small, the finite Larmor radius effects for the electrons are incorporated, obtaining that they are capable of changing the drift wave stability in certain regions of the thruster. Electron trapping effects are expected for the large amplitude waves.