Effects of Spacecraft Potential on Secondary Electron Yields in Geosynchronous Orbit

University of Utah

Surface charging due to interactions with the earth's plasma is a hazard for orbiting spacecraft. Secondary electron (SE) emission is an important physical process in spacecraft charging. Current spacecraft charging models do not consider the SE energy or angular distributions and their implications for estimating the return of SE to the spacecraft. Comprehensive work on the application of SE energy and angular distributions to spacecraft charging has been published [Nickles et al., 1999] and part of that work is summarized here. The application of SE energy distributions to the case of positive charging in geosynchronous orbit is discussed and shown to impact the cutoff voltages required to assume that secondary electron yields are effectively zero. The ramification of the SE angular distribution for cases of negative charging in geosynchronous orbit is also briefly discussed.