Particle simulation of the acceleration grid aperture erosion in ion thruster

In order to investigate the characteristic and impact factors of the aperture enlargement erosion of the ion thruster accelerator grid, the Particle in Cell-Mont Carlo (PIC-MCC) method combined with the sputtering erosion model was used to simulate the distribution of the beamlet ions and charge exchange (CEX) ions. Then the aperture enlargement erosion rate of the NSTAR ion thruster accelerate grid was calculated and the value was 0.0176 μm/h. The effects of thruster operating parameters and grid geometry parameters on the aperture enlargement erosion rate were studied. Combined with the computational results, a model for the prediction of the aperture enlargement erosion rate were established. The results indicate that among all the factors the beamlet current and neutral gas density have the greatest impact on the erosion rate. Thus the essential means to extend the life of the accelerate grid can improve the flatness of the plasma distribution in the discharge chamber exit and the propellant utility.