Comparison of 2-D and 3-D models of grid erosion in an ion thruster

Numerical results of particle-in-cell/Monte Carlo calculations of accelerator grid erosion in an ion thruster are presented. Specifically, it is shown that a three-dimensional model is required to account for the experimentally observed pitting of the accelerator grid between grid apertures. Some comparisons with earlier two-dimensional, axisymmetric model are made, and it is shown that, for identical operating conditions of the thruster, the wear-through time in the three-dimensional model is about two to three times higher than that obtained previously with the two-dimensional model, namely on the order of 10,000 hours for sample calculation.