空间在轨环境下的30cm离子推力器三栅极组件间距变化仿真分析

Hot Gap Change Simulation for Triple Grid of a 30cm-Diameter Ion Thruster under Space Environment

采用有限元仿真(FEM)与地面热平衡试验验证相结合的方法,计算并模拟了30 cm离子推力器处于在轨环境时,有、无主动热控对三栅极相对位移变化造成的影响,并对目前离子推力器设置的工作启动流程可能造成的打火风险进行了预估。结果显示:三栅极组件的热形变方向均为法向方向,且栅极中心区域的间距最小;在-269℃在轨极限环境温度下,推力器在5 kW工作模式下温度平衡后的屏栅与加速栅最大热态间距为0.14 mm,加速栅和减速栅则已发生贴合;在受太阳辐照以及卫星帆板恒温边界的影响下,栅面最低初始温度为-102℃;当推力器主动热控保证温控点为20℃时,栅面最低启动温度为-25℃,且推力器工作8000s后,屏栅与加速栅、加速栅与减速栅的最小间距分别稳定在0.25 mm和0.20 mm;当推力器主动热控保证温控点为50℃时,推力器工作9000s后,屏栅与加速栅、加速栅和减速栅最小间距分别稳定在0.31 mm和0.30 mm,能够满足0.25 mm的栅极安全打火间距要求。

The finite element method(FEM)and ground thermal equilibrium test verification are used to simulate the thermal displacement of the triple grid in on-orbit working condition without and with active thermal control equipment,and the breakdown risk is evaluated under the current start-up process of the ion thruster.The results show that the thermal deformation directions of the three grids are all normal direction,and the minimal spacing position is in the central area of the triple grid.The largest hot gap between the screen grid and the accelerator grid is 0.14 mm,and the accelerator grid and the decelerator grid are fitted when the thruster is operating at 5 kW work mode under-269℃low temperature conditions on orbit.The lowest initial temperature of the triple grid is-102℃under the influence of the solar radiation and steady temperature of the satellite panel.The initial temperature of the grids are-25℃when the temperature of the control point reaches up to 20℃.Meanwhile,the minimal hot gap of the screen grid and the accelerator grid,the accelerator grid and the decelerator grid are 0.25 mm and 0.20 mm after working for 8000 s,respectively.When the temperature of the control point reaches up to 50℃,the minimal hot gap between the three grids are 0.31 mm and 0.30 mm then after working for 9000 s,respectively,which is able to meet the requirement of 0.25 mm safe breakdown spacing.