Laboratory Investigation of Dielectric Materials Exposed to Spectral Electron Environments(1 to 100 keV)

This paper discusses laboratory tests performed with a spectral energy electron source (1 to 100 keV) on dielectric samples of OSR, Kapton, Teflon, and Alphaquartz. We describe how the spectral source was fabricated and include dielectric charge and discharge data obtained in three spectral environments: dN/dE = const., dN/dE = E-1 and dN/dE = E-2 where dN is the number of electrons found in each energy bin, dE. The spectrum dN/dE = E-2 keeps all samples from charging more negative than -5 kV and produces discharges on Teflon. The spectrum dN/dE = const. produces the highest negative charging (up to -18 kV for Teflon and -9.5 kV for OSR) on the samples and causes large discharges, 1 >> 10 A on Teflon and OSR. Two types of discharges appear to dominate the kinds of discharge seen: These are 1 >> 10 A with pulsewidths τ > 200 ns and 1 < 5 A with τ < 20 ns. The largest discharges observed in spectral tests compare favorably with those observed in monoenergetic tests. Results from the fabrication and testing of the spectral source promise to provide a valuable data base with which to compare basic discharge models.