Charging and Arcing Test on Semiconductive Coated Solar Coupon Panel

Two types of semiconductive antimony tin oxide (ATO) coating (single and multiple layers) have been applied on solar cells and a charge accumulation test has been performed under high-energy electron beams simulating a geostationary earth orbit environment and ECR plasma simulating a low earth orbit environment. No charge has been accumulated on the coated solar cells whereas a high charge has built up on the noncoated solar cells, confirmed by a noncontacting surface potential probe. Electrostatic discharge (ESD) testing has also been performed on both the coated and noncoated solar cells; however, no ESD has been detected on the coated solar cells. Therefore, ATO coating on solar cells can be used for charging mitigation. The performance of coated and noncoated solar cells onboard the HORYU-II, the high voltage (300 V) technology demonstration satellite made by the students of Kyushu Institute of Technology, has also been tested in a ground plasma chamber. After launching the HORYU-II, high voltage generation was confirmed. However, so far, we have not conducted arcing mitigation technology tests on orbit. In spite of the charging mitigation feature of ATO coating, the current-voltage characteristic of coated solar cells shows a power decrease, which needs to be studied along with ATO coated layer degradation due to atomic oxygen, vacuum ultraviolet irradiation, energetic protons, thermal cycling, and so on.