Charging behavior of spacecraft materials under electron irradiation

A substorm simulation facility is described, and investigations of the surface potential of Teflon, Kapton, and thermal control paints under electron irradiation are outlined. Electron irradiation up to 25KeV at a current density up to 10 nA/sqcm is possible. Current density uniformity is 20% for a sample surface of 1sqm. Tests indicate that irradiation induces higher surface conductivity, but that bulk conductivity is relatively unchanged. No arc discharges are observed for Teflon samples thicker than 5 mil, since they reach their equilibrium potential.