Difference in discharge threshold voltage on spacecraft solar array panel between vacuum ultra violet and electron beam

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K04839
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 24010:Aerospace engineering-related
• Research Institution: Kyushu Institute of Technology
• Principal Investigator: Toyoda Kazuhiro 九州工業大学, 大学院工学研究院, 教授 (10361411)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 帯電放電 / 表面電位 / 放電閾値 / ポッケルス効果

Outline of Final Research Achievements

In geostationary orbit, satellites are charged and discharged by ultraviolet rays and electrons, so discharge generation threshold measurements are performed as a countermeasure before launch. Recent experiments have shown that the discharge threshold voltage on solar cells is lower when ultraviolet rays are used than when electron beams are used. To clarify the cause of this, we used the Pockels effect to measure the surface potential at the edge of the coverglass in detail.
A two-dimensional distribution of the surface potential was obtained using a surface potential measurement system based on the Pockels effect, which was constructed using a Pockels element that changes its refractive index depending on the electric field. We were also able to confirm the difference in the surface charge distribution between UV and electron beams. Furthermore, the difference was also clarified by the charging analysis tool.

Free Research Field

航空宇宙工学

Academic Significance and Societal Importance of the Research Achievements

打ち上げ前に実施している太陽電池パネルの帯電放電試験では、放電のエネルギーを決定する放電閾値電圧が非常に重要となる。帯電の原因となる電子と紫外線で放電閾値電圧が異なることを実験的に明らかにし、その原因がカバーガラス端近傍の表面電位分布の違いにあると推測し、今回ポッケルス効果を用いて原因を明らかにした。ポッケルス効果により詳細な表面電位分布を得ることは学術的に意義があり、今後もこの計測方法を利用して新たな問題を解決できる。また、地上試験で紫外線と電子ビームのどちらを使用するべきかを明らかにしたこで社会的に大きな意義があった。