Flashover Current Pulse Formation and the Perimeter Theory

Electrostatic discharges on the spacecraft solar array surfaces have been studied for over 40 years. Multiple tests in many laboratories have been performed to reveal the mechanisms of current pulse formation, to determine plasma expansion speed and dimensions of neutralized surface area, and to define the parameters of the electric circuits to be able to adequately simulate space discharges in plasma chambers. Initially, a thorough analysis of all the available experimental data is performed to achieve progress in the creation of a satisfactory theoretical description of pulse wave forms and surface neutralization processes. It is shown that there are two main reasons for the significant variations observed in pulse wave forms, durations, and amplitudes; differences in test arrangements and pure statistical variations caused by the random nature of arc inception and development. Then, the theoretical model of flashover current pulse formation due to coverglass charge neutralization at the plasma perimeter is carefully considered and confronted with existing experimental data. It is found that this theory contains some appropriate elements but cannot be applied for quantitative explanation of pulse wave forms. The comparison of theoretical results and experimental data clearly shows that there is no (and there cannot be) such thing as a standard pulse. To estimate the possibility of detrimental effects from primary arcs, these events must be studied and analyzed statistically.