極軌道衛星の太陽電池パドル裏面の帯電・放電抑制に関する地上試験

Abstract

In case of a polar orbiting satellite, insulative surfaces located on the wake side of solar array paddle can be charged negatively by aurora electrons. We carried out laboratory experiments to evaluate risks of charging and arcing on thermal control film surfaces attached on a solar array paddle backside. We used two test coupons of different design. Both of them used the same materials of flight hardware as the Advanced Land Observing Satellite (ALOS) and the Optical Inter-orbit Communications Engineering Test Satellite (OICETS), which are domestic polar orbiting satellites. When the thermal control film surface was insulated and a silver layer was not connected to coupon ground, the film surface was charged to a negative value 1–2kV lower than the electron beam energy. Many primary arcs and flashover were observed at the edge of silver layer and film surface, respectively. Some areas of silver layer were destroyed by primary arcs. On the other hand, the film with conductive coating connected to a substrate with resistance of 106–109Ω suppressed surface charging and flashover on the film under the electron flux of 1×1015–1.4×1017m- 2s- 1, effectively. We made a new coupon which had three features to give improved performance of arcing and charging mitigation. (1) Connecting the silver layer to the substrate by conductive adhesive to suppress charging and arcing at the edge of silver layer. (2) Film surface coating by conductive material and connected with conductive adhesive to avoid charging. (3) Hiding all the edges of silver layer by conductive adhesive. This coupon suppressed any arcing and charging on the film surface up to 20keV electron beam irradiation.