Influence of high energy electrons and protons on secondary electron emission of cover glasses for space solar cells

We measured the secondary electron emission (SEE) of cover glasses for space solar cells by beam blanking scanning electron microscopy (BBSEM) with a Faraday cup. The SEE yield of the cover glass is very important for analyzing the charge profile of the satellite. We observed the SEE of a cover glass coated with ZrO₂. This cover glass was chosen for the National Space Development Agency of Japan´s (NASDA´s) Engineering Test Satellite-8 (ETS-8), which is to be launched in 2004. We found the maximum SEE yield of the cover glass to be about 3 for a 1 keV electron beam and that SEE yield depends on the coating material on cover glasses. We investigated the influence of high-energy electrons and protons around satellites on the SEE of a cover glass. As a result, we found that the SEE of a cover glass irradiated with high-energy electrons and protons decreased. This indicates that the differential voltage degreasing with increasing satellite operation.