Charging Dynamics of Dielectrics Irradiated by Low Energy Electrons

A recent study by Gross et al. showed the possibility of positive charging of dielectric materials by low energy electron irradiation. In this paper we model the charging process allowing us to predict the voltage builtup or decay and the corresponding charging currents under various initial potential conditions of the dielectric. The model incorporates the secondary electron emission (SEE) yield curve and the energy distribution of the secondaries. The energy distribution is essential to obtain the correct charging behavior for beam energies smaller than the second crossover energy of the SEE yield curve. The results agree, in general, with experimental data Further it is shown theoretically that knowledge of the charging current and the corresponding voltage behavior of an irradiated sample can be utilized to determine the secondary electron yield curve for dielectrics and conductors.