Erosion Mechanisms at the Outer Front Pole Cover of a Magnetically Shielded Hall Thruster

Erosion of the outer front pole cover in a magnetically shielded Hall thruster is mostly caused by the high energy ions of the beam. We show in this article that erosion predictions for the outer pole are highly sensitive to small variations in the experimentally informed anomalous collision frequency distribution inside the channel that result in the axial displacement of the stagnation and sonic point of the ions. We produce for all the reported operating conditions numerical solutions using Hall2De that agree well with both laser-induced fluorescence and wear measurements. We also report on the first set of Hall2De simulations that make partial use of first-principles closed-form model for the anomalous collision frequency in the region inside the channel where we found a strong correlation between the erosion predictions and the anomalous collision frequency. Of the two cases shown exhibits good agreement with LIF measurements at the channel centerline and reproduces oscillations, the OFPC erosion rate and off-centerline LIF measurements accurately. This represents a promising first step towards a fully ab initio simulation.