Ion sputtering erosion of channel wall corners in Hall thrusters

In order to evaluate the effect of corner contour evolution stability on the erosion rate of exit edge and the contour evolution of Hall thruster channel wall corners, the erosion rate of exit edge and the contour evolution of initial right-angle corner have been investigated using the wave approach based on Huygens' principle for both uniform and non-uniform ion sputtering conditions and the effect of corner contour evolution stability on the eroded contour predicted by reconstructing Huygens' wavelet at the channel edge. Geometric analyses show that the stability of corner contour evolution, which is determined by the ion incident angle only, has a significant effect on the erosion rate of exit edge and the contour evolution of channel wall corner while the initial right-angle of channel wall corner cannot be kept intact under non-uniform ion bombardment. The similarity between simulation and experimental results indicates that the corner contour evolution stability is likely to be one of the major causes for the formation of corner eroded contour which has a significant effect on the edge erosion rate of the Hall thruster channel wall.