Influence of secondary electron emission on plasma-surface interactions in the low earth orbit environment

Abstract

The low earth orbit plasma experienced by exposed interconnect-dielectric junctions commonly found on spacecraft solar panel surfaces was modeled using a fully kinetic particle-in-cell (PIC) simulation of both ambient ions and electrons. From time-accurate simulations we observed that the plasma sheath had a formation time somewhere between the ion and electron time scales of 17 μs and 30 ps, respectively and electron and ion velocity distribution functions were observed to be highly non-Maxwellian. Comparison of the electron plasma sheath thickness with analytic cylindrical sheath models gave reasonable agreement if the embedded biased interconnect voltage was sufficiently high to cause the dielectric surface to act as a free electron flowing medium. Finally, it was found from the fully kinetic PIC simulations that the fundamental mechanism behind parasitic current is closely related to electron avalanche and the fraction of SEE emitted from different avalanche levels as well as the current collected at the interconnect could be modeled by a power law series for avalanche levels greater than two.