LIPS-300离子推力器加速栅电压的优化设计

Optimization of LIPS-300 Ion Thruster Accelerator Voltage

在不改变推力器几何结构的前提下,为了获得LIPS-300离子推力器的最佳加速栅电压,采用半经验分析和数值仿真计算相结合的方法分析了加速栅电压分别为-180V、-190V、-200V、-210V和-220V时LIPS-300离子推力器栅极组件引出束流过程中束流离子从非平衡态到平衡态的演化过程,通过数值模拟计算得到了推力器运行过程中交换电荷离子轰击溅射到加速栅壁面的产额,利用寿命预测的半经验计算方法对5种情况下LIPS-300离子推力器的栅极寿命进行估计,分析了关键失效模式,通过对比获得了LIPS-300离子推力器的最佳加速栅电压。计算结果显示,在现有几何结构下加速栅电压的变化不会影响栅极组件的引出性能;加速栅下游更易受到交换电荷离子的轰击溅射;加速栅电压从-180V变化至-220V过程中,影响栅极寿命的关键失效模式为电子反流失效;对比5种情况下发生电子反流和结构失效时对应的栅极寿命可以发现,LIPS-300离子推力器加速栅电压最佳值应为-220V,此时对应的栅极寿命为16 170.4h。

Accelerator voltage directly affects the electron back streaming and acceleration grid sputter erosion. Therefore, how to obtain the best values of accelerator voltage is important for an ion thruster. The semi-empirical analysis method combined with the numerical simulation was used to analyze the equilibrium evolution of the beam current extracted from the LIPS-300 ion thruster grid and the grid lifetime was calculated. By using the numerical model, the sputter erosion rate that CEX sputtered on the surface of the acceleration grid was obtainded. Then applying this erosion rate to the theoretical model, the lifetime of the LIPS-300 ion thruster was estimated and the failure modes for the five different accelerator voltages were analyzed. The results show that the change of the accelerator voltage would not affect the performance of the LIPS-300 ion thruster gird. For the LIPS-300 ion thruster, the downstream of the acceleration grid would be more vulnerable to CEX sputtering erosion. While the accelerator voltage is changed from --220 V to --190 V, the key failure modes of the LIPS-300 ion thruster gid is electron backstreaming failure. By comparing the lifetime of the grid for the five different accelerator voltages, the best voltage is --220 V and the corresponding lifetime is 16 170.4 h.