Vacuum DC breakdown characteristics between grid electrodes with ion sputtering

作者：H.‐J. LIU, Wenxuan Liu, Guangyu Sun, Yue-Lin Liu, Liwei Zhang, Sheng Zhou, Changchun Qi, Anbang Sun, Guanjun Zhang · 发表于：Journal of Physics D Applied Physics · 年份：2025 · DOI：10.1088/1361-6463/ada6cf · 被引用次数：9 · 研究领域：Plasma Diagnostics and Applications、High voltage insulation and dielectric phenomena、Electrostatic Discharge in Electronics

Abstract In ion thrusters, grid electrodes are biased at high voltage to extract and accelerate ions. However, they are susceptible to vacuum breakdown which considerably undermines the ion thruster performance. To optimize the grid electrode design and improve the ion thruster longevity, the impact of ion sputtering on the vacuum direct-current breakdown characteristics of grid electrodes is systematically examined. The adopted seven-aperture grid electrodes are made of three materials including molybdenum, graphite, and stainless steel, which are exposed to Ar+ and Xe+ sputtering at energies of 400 eV and 1000 eV for durations ranging from 0.5 to 8 h. It is found that the initial breakdown voltage, which means the first breakdown voltage after sputtering, generally decreased regardless of the electrode material as the sputtering time increased. However, the breakdown voltage rapidly increases with more repeated discharges. Each kind of electrode material demonstrates unique responses to ion sputtering and breakdown. In comparison with metal electrodes, the graphite surface is relatively easy to appear defects but exhibits the least insulation degradation. The metal surface remains relatively smooth, but breakdown voltage is significantly affected, with electrode materials such as stainless steel failing to recover to their initial insulation levels. Xe+ sputtering leads to greater breakdown voltage fluctuations during repeated discharges due to higher sputtering yield. Dark...