Charging and Discharging Characteristics of Dielectric Materials Exposed to Low- and Mid-Energy Electrons

Samples of dielectric materials have been irradiated with low- (1 to 25 keV) and mid-energy (25 to 100 keV) electrons. Charging and discharging characteristics for samples of OSR, mylar, Kapton, perforated Kapton and Alphaquartz are discussed. Results of tests conducted with monoenergetic midenergy electrons indicate that the worst-case peak discharge current, Is, is relatively constant with exposure energy; that dls/dt is relatively constant with exposure energy; and that the predischarge surface potential, Vi, is only a weak function of energy. Results of irradiating samples of OSR, mylar, and Kapton with low-energy and mid-energy electrons indicate that the surface potential may be tailored to low values (Vs <2 kV) and yet still achieve discharges (on OSR and mylar samples), and that for an OSR sample, the frequency content of these discharges is much higher than for discharges observed during exposure to monoenergetic low-energy electrons alone.