中文摘要：

以离子发动机栅极系统为研究对象,基于网格质点法（PIC）,建立了二维数值计算模型.利用模型能够较好地模拟离子在栅极系统中的运动,得到栅极系统周围的电势分布以及离子和电子的密度分布等.进一步的计算结果表明,在几何参数一定的条件下,加速栅极电压以及加速栅极孔径对加速栅极下游的电子密度分布有重要的影响.选取合适的加速栅极电压和孔半径,可以阻止电子回流的产生,使离子发动机获得较佳的性能.

英文摘要：

Based on particle-in-cell method, a two-dimensional numerical model has been developed to investigate the ion beam extraction phenomena through the optics system of ion thruster. According to the calculation results, the distribution of electric potential between screen grid and accelerator grid, the ion and electron spatial distribution were obtained for various accelerator voltages and accelerator grid radii. The simulation results show good agreement with the experimental data. The results indicate that the accelerator voltage and the accelerator radius have great influences on electron backstreaming. Electron backstreaming happens when the absolute value of accelerator voltage is more negative. The electrons move downstream with the decrease of accelerator voltage. Moreover, electron backstreaming occurs with the enlargement of accelerator radius. Under moderate accelerator voltage and accelerator radius, the electron backstreaming will not happen, and the ion thruster will reach its better performance.