Conduction and Charge Storage in Electron Irradiated Spacecraft Insulators

Charge, storage and conduction processes were studies in four spacecraft insulators, FEP Teflon, Kapton, Mylar and fused quartz exposed to monoenergetic electron beams with energies of 5-27 keV as a function of particle flux, sample thickness, applied external bias and temperature. The experimental data was used to determine some of the parameters which control the deposition and transport of keV electrons in representative spacecraft insulators found on the surface of communication and other satellites placed in geostationary orbits. Properties determined include location of the charge deposition centroid, dark, radiation, delayed and surface conductivities. These parameters were then used in the phenomenological transport model to interpret the observed charge leakage behavior under various exposure conditions. In the model, the sample is divided into two regions. In the irradiated region, radiation-induced conductivity is the predominant conduction mechanism. In the nonirradiated region, space-charge limited currents predominate.