Estimation and control of low (<100 V) potential on a dielectric target irradiated by an electron beam at fore-vacuum pressure

Abstract

We propose a method for estimation of the relatively low values (less than 100 V) of the steady-state negative potential built-up on a dielectric target irradiated by an electron beam at fore-vacuum pressure. The method is based on comparing the intensity of the emission lines of excited helium to similar emission lines for the known potential of a metal target. At low values of potential, we measured the plasma parameters in the region of the target and determined the contribution to ionization processes from each of the electron components: fast beam electrons, secondary electrons from the target, and plasma electrons.