Charge buildup in electron-irradiated dielectrics

Abstract

Irradiation of dielectrics with nonpenetrating electron beams generates long-lasting space charges. A simple experimental and mathematical method is developed for the investigation of charge buildup during irradiation. Time-resolved charge measurements carried out with pulsed beams of 1-MeV electrons, pulse duration of 4×10−5 sec, and an average current density of 10−2 A/cm2 were used to analyze effects of charge leakage caused by radiation-induced conductivity and electron range reduction caused by retardation of the incident electrons in the internal space-charge field. Leakage is found to predominate in silica and borosilicate glass while range reduction predominates in polyethylene.