防溅射靶对离子推力器背溅射沉积污染的影响

Influence of anti-sputtering target on ion thruster back sputtering deposition

针对目前对真空舱背溅射沉积污染的计算模型误差较大的问题,对地面实验中离子推力器的背溅射沉积污染效应开展了研究,提出了更精确的计算模型。由于Reynolds的模型对束流密度在轴向上误差较大,采用改进型的离子束流模型对偏离推力器80cm位置的真空舱背溅射沉积率做了计算,并与实验结果对比校验,结果吻合较好。用校验过的模型对光舱环境和防溅射靶环境的背溅射沉积效应开展研究,研究结果显示:光舱工况的返流沉积率为2.36×10-10 g/(cm2·s),安装防溅射分子屏的工况在推力器上的背溅射沉积率为2.51×10-11 g/(cm2·s),结果表明添加防溅射分子屏后背溅射沉积污染量可以降低近1个量级。

Considering very large error of current back sputtering model,a model of higher accuracy was proposed.A improved ion current density model was used to calculate the back sputtering deposition in the 80 cm position deviating from the thruster while the Reynolds model had a big error.The calculated results agreed well with the experiment result.Then,the verified model was used to calculate the back sputtering deposition of bare chamber and the chamber with anti-sputtering target.The results showed that,the deposition rate of bare chamber case was 2.36×10-10 g/(cm2·s),while the anti-sputtering target shield case was 2.51×10-11 g/(cm2·s).It was clear that the back sputtering deposition yield with anti-sputtering target shield was an order of magnitude lower than the vacuum chamber without the anti-sputtering target.