Total Electron Emission Yield of Solar Cell Coverglass and Optical Solar Reflector

Electron-induced secondary electron (SE) emission from space insulating materials is a very important factor in understanding spacecraft charging behavior. Because of the injection of primary electrons (PEs) and the emission of SEs in the surface layer of insulating materials, the target surface can be either negatively or positively charged. In the conventional measurement methods, a single short, low-density pulsed e-beam, charge neutralization using low energy flood e-gun and UV light, and charge dissipation by heating is used. In this paper, a pulsed scanning method for the total electron emission yield measurement of insulating, semiconducting or conducting solid materials is proposed. A total electron detector with large hollow space and insulating spacer was designed, and a pulsed yield scanning measurement system was developed. This method can avoid influence from the charged surface of the insulating material. Using the system, the total SE emission yields of 200 nm thick Au coating on glass, and 11 kinds of solar cell coverglasses and optical solar reflectors produced by Qioptiq have been reported, as induced by a 30 μs pulse of PEs with ~ 20 nA incident beam current and energies up to 2500 eV.