Processes on the Glass Surface under Irradiation with Medium-Energy Electrons

— The results of experimental studies of processes occurring on the surface of protective glasses of solar batteries and elements of reflective coatings of high-orbit artificial Earth satellites (AESs) when exposed to electrons with an energy of 30 keV are presented. The samples studied have been made on the basis of K‑208 glass, while the samples of reflective coatings differ in the presence of silver and stainless steel layers on the reverse surface of the glass plates, deposited sequentially by magnetron sputtering. The electron irradiation of the samples was carried out in a vacuum of 10 –4 Pa at a particle flux density (φ) from 1 × 10 9 to 8 × 10 12 cm –2 s –1 . The surfaces of the samples before and after irradiation have been examined by atomic force microscopy (AFM). On the irradiated surface of glass samples, electrostatic discharges (ESDs) arise, the parameters of which are characterized by oscillograms of generated electromagnetic pulses. In addition, leakage currents to the metal substrate have been measured for elements of reflective coatings. It has been found that changes in the structure of the irradiated surface of the samples are attributed to the appearance of ESD traces and the formation of gas-filled bubbles. Moreover, changes in the back surface of glass plates have been presumably caused by shock waves formed when ESD occurs on the irradiated surface. The ESD frequency and leakage currents increase with increasing electron flux density in the specified range, but these dependences showed significant differences. Measurements at a constant value of φ = 2.0 × 10 10 cm –2 s –1 have revealed that an increase in the electron fluence from 10 14 to 5 × 10 16 cm –2 led to a higher ESD frequency, while the amplitude of electromagnetic pulses decreases.