天体物理学と航空宇宙技術

LEO Spacecraft Charging and Discharging Induced by High Voltage Solar Arrays

Abstract

Jianguo H, Liu Guoqing and Jiang Lixiang

The charging and discharging induced by application of high voltage solar arrays were attracting increasing attentions recently. In this paper the associated models and tests conducted recently are introduced. For the rapid charging observed on International Space Station recently, a model is developed based on Ferguson et al.’s theory and gives satisfactory calculations consistent with the observations. It shows that the rapid charging events are driven by the abrupt increase of the panel voltage at eclipse exit, and also due to the fact that the charging of the cover glasses by the ambient plasma can’t response quickly enough to choke off the electron collection of the solar panel, as a result the structure is rapidly charged to a significant potential within a few seconds. The rapid charging is a type of non-equilibrium charging phenomena and will display normal charging when evolving to equilibrium. In the other hand, the discharges induced by high voltage solar arrays generally occur at triple junction in the presence of an inverted potential gradient from the metal to the dielectric. When a primary arc occurs at solar cell string gaps with high string voltage it will induce secondary arc. Both primary and secondary arc thresholds depend on solar array configurations. We tested the dependence through tests and found that application of wide cell gaps and RTV adhesives help to increase the thresholds for both primary and secondary arcs. But for secondary arc, application of RTV adhesives tends to result in more significant permanent sustained arcs although it postpones the arc occurrence.