Electron-beam charging of plasma-coated spacecraft dielectrics

Research results are described on the charge accumulation and arc discharging of coated dielectric sheets exposed to a 20-keV electron beam. The dielectric sheet substrates are Kapton and Mylar, and the coatings are plasma-deposited amorphous hydrogenated silicon (a-Si:H), silicon nitride (P-SiN), and silicon dioxide (P-SiO₂). Arc discharges are characterized by their current pulse shape and by their appearance as recorded using a CCD (charge coupled device) camera. Results indicate that P-SiO₂ and P-SiN coatings on Kapton prevent discharge occurrence. Other coating-substrate combinations do not prevent discharges but do modify them