Characteristic and Mechanism Analysis of Aperture Barrel Erosion at Edge of Decelerator Grid of Three-Grid Ion Thrusters

To study the characteristics and mechanism of ion thruster decelerator grid aperture erosion at the edge, immersed finite element particle-in-cell (IFE-PIC) method combined with the sputtering erosion model was used to simulate the distribution of beam ions between grids. The characteristics and mechanism of ion thruster decelerator grid aperture barrel erosion at the edge were obtained. The results show that the direct impact of beam ions leads to polygonal erosion morphology. The reason for the uneven erosion depth in the circumferential direction is that the influence of the upstream sheath of the surrounding aperture on the edge aperture is too large, resulting in uneven distribution of beam ions. Hence, to avoid this kind of direct ion etching, the polygonal aperture is suggested at the edge of ion optics.