Calculation on 2 cm ECRIT Thrust Regulation Based on 3D PIC Numerical Simulation Method

基于三维PIC数值模拟的2 cm ECRIT推力控制计算

¹ School of Astronautics, Northwestern Polytechnical University, Xi'an 710072, China
² School of Power Science and Engineering, Harbin Institute of Technology, Harbin 150001, China

Received: 16 October 2019

Abstract

Drag-free control is the key technology for space gravitational wave detection, which will be completed by miniature thruster. 2 cm Electron Cyclotron Resonance Ion Thruster (ECRIT) may be used for the drag-free control. Therefore, the 3D PIC method is used to estimate the thrust regulation of 2 cm ECRIT through simulating the property of ion extracting from the double-grid system. Through analyzing the thrust performance and grid focusing property under different grid apertures, the better grid structure is selected for the subsequent calculation. On this basis, the influence of grid voltage and the ion density on the performance of the thruster is analyzed. The result shows that reducing grid aperture can reduce the thrust, but it also affects the focusing property of the grid. Changing the ion density can adjust the thrust in a wide range. At given grid structure and ion density, there is a suitable grid accelerating voltage range to ensure the best ion focus characteristics. Considering the thrust performance and focusing characteristics, the grid structure with screen and accelerating grid aperture in 0.6 mm and 0.34 mm is selected. When the ion density is 1×1 017, 0.7×1 017, 0.4×1 017 and 0.2×1 017 m^-3, the thrust can range from 5.05 to 141.44 μN through adjusting the grid accelerating voltage. This study can provide information for analyzing the possibility of the thruster application.

摘要

无拖曳控制是空间引力波探测的关键技术，主要由微型推力器完成。微型电子回旋共振离子推力器（ECRIT）体积小、推力可调，可用于空间引力波的无拖曳控制。基于三维PIC数值模拟方法计算微型2 cm ECRIT的推力控制范围，分析其用于无拖曳控制系统的可行性。首先计算不同栅极孔径下的推力性能和栅极聚焦特性，获得合理栅极结构，再计算栅极电压、栅极前离子密度对推力器性能的影响，获得满足无拖曳控制要求的推力器性能参数范围。结果表明：减小栅极孔径能降低推力，但同时影响栅极聚焦效果；调节栅极前离子密度可大范围调节推力；在给定的栅极结构和栅前离子密度下，存在合适的栅极加速电压区间保证离子的良好聚焦。综合考虑推力性能和栅极聚焦特性，选择屏栅孔径0.6 mm、加速栅孔径0.34 mm的栅极，当栅极前离子密度分别为1×10¹⁷，0.7×10¹⁷，0.4×10¹⁷，0.2×10¹⁷ m^-3时，通过调节加速电压，可实现5.05~141.44 μN的推力调节。此研究将为分析ECRIT应用于引力波探测的可行性奠定基础。