Characteristic of charge accumulation in glass materials under electron beam irradiation

Space charge formation in various glass materials under electron beam irradiation was investigated. The charging of spacecrafts occurs in plasma and radiation environments. In particular, we focused on an accident caused by internal charging in a glass material that was used as the cover plate of a solar panel array, and tried to measure the charge distribution in glass materials under electron beam irradiation using a pulsed electroacoustic (PEA) method. In the case of quartz glass (pure SiO₂), no charge accumulation was observed either during or after the electron beam irradiation. On the contrary, charge accumulation was observed in glass samples containing metal oxide impurities. It is found that the polarity of the observed charges depends on the contents of the impurities. To identify which impurity dominates the polarity of the accumulated charge, we measured charge distributions in several glass materials containing various metal oxide impurities. Furthermore, the dependence of the polarity of accumulated charges on the composition of glass materials is discussed using energy band models