Computing the Wall Erosion Rate of a Low-Power Hall Thruster Using Particle-in-Cell Numerical Simulations

We present a numerical study of the erosion of channel walls applied to the PHALL Hall thruster being developed at the Plasma Physics Laboratory at the University of Brasilia. The simplified two-dimensional model retains the axial and radial directions to evaluate the erosion rate due to energetic ions. Plasma particles and fields are solved using the particle-in-cell and Monte Carlo collision techniques. The electrostatic potential and ion density profiles are obtained after the simulation reaches the steady state. We compute the channel wall erosion rate from the time series of the number of sputtered particles. We also perform and analyze a simulation of an SPT-100 Hall thruster. Our results show that the erosion acts mainly near the middle of the channel walls of the PHALL thruster, in agreement with patterns of wall material degradation observed in the laboratory device after experimental tests. The implications of the erosion pattern predicted for the PHALL thruster are discussed.