Parasitic current collection by solar arrays in LEO

Summary form only given as follows. Solar cells at potentials positive with respect to a surrounding plasma collect electrons. Current is collected by the exposed high voltage surfaces: the interconnects and the sides of the solar cells. This current is a drain on the array power that can be significant for high-voltage arrays. In addition, this current influences the current balance that determines the floating potential of the spacecraft. One of the objects of the Air Force (PL/GPS) PASP Plus experiment is an improved understanding of parasitic current collection. As part of the PASP Plus program, we are using computer modeling to improve our understanding of the physical processes that control parasitic current collection. We have done detailed calculations for a range of geometries, LEO plasma conditions, applied potential, and material parameters. From the results of the detailed calculations, we have developed simple formulas for the current collected as a function of applied voltage, plasma conditions, and geometry. We are using flight results to validate this approach and the resulting formulas.