The statistical electron environment for Defense Meteorological Satellite Program eclipse charging

Abstract

Precipitating high‐energy electrons can produce high‐level (≥ 100 V negative) vehicle to plasma potentials on spacecraft operating in high‐inclination, low‐altitude polar orbits. In order to precisely specify the charging level, both the incident electron population and the spacecraft materials properties must be accurately defined. This is because the effect of the total incoming electron flux is largely balanced by the production of backscattered and secondary electron fluxes escaping the satellite surface. In this paper we categorize and model the precipitating electron spectra during 11 Defense Meteorological Satellite Program (DMSP) charging events that occurred during the winter months of 1983. During the charging events the electron energy distribution functions have a large high‐energy component, are definitely not single Maxwellian in shape, and are often rapidly changing. The spectra can be classified into four types, three of which we model. The critical parameters in the models are temperature and density of the multiple Maxwellian components and the energy at transitions in the spectral shape. The average values of these parameters are calculated for two levels of DMSP charging. The model electron spectra are then used to calculate the net electron flux charging current for various satellite materials using two different formulations of electron secondary and backscatter yield coefficients. The electron charging currents differ significantly for the two cases.