Development of 400 V Solar Array Technology for Low Earth Orbit Plasma Environment

Abstract

To realize a 400 V operation in low Earth orbit (LEO), problems of arcing caused by interaction between spacecraft and surrounding LEO plasma must be overcome. This paper is a summary report of the laboratory tests carried out to develop a 400 V solar array technology. Among various designs tested, a design of covering a solar array surface with transparent film, called film coupon, was the most promising mitigation method to prevent arc inception. The authors carried out various tests on the film coupons considering a realistic situation encountered in orbit. The coupon biased to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$-$</tex> 400 V in LEO-like plasma had no arc for more than 25 h. Other tests involved UV exposure, atomic-oxygen exposure, thermal cycling, and debris impact. Conductive substrate made of carbon fiber reinforced plastic suffered many arcs at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$-$</tex> 400 V. Sustained arc between a solar cell and the substrate was also observed upon a simulated debris impact. Therefore, the use of flexible substrate is adequate for 400 V solar array in LEO environment. To avoid the snapover effect near the positive end of the array circuit, only the negative part of the array circuit exceeding the arc-inception threshold should be covered by film, or an electron collector should be deployed.