Effects of excitation rise-time and charge injection conditions on the transient field and charge behavior for unipolar conduction

Abstract

Recent analysis using a unipolar ion mobility conduction model is continued and extended by taking into account the experimental realities of excitation rise-time and charge injection threshold conditions. The transient behavior of the bulk electric field and space charge distributions as a function of time and position as well as the resulting time dependence of the terminal voltage and current are found for an imposed voltage or current excitation with non-zero rise-time, contrasting the behavior between field or charge specification at the emitter electrode with charge injection onset once the emitter electric field exceeds a threshold value. Representative plots of field and charge distributions as well as voltage and current time dependence for various excitations, rise-times, and boundary conditions are presented. Important time constants which can be correlated to experiments under these various conditions are tabulated and where possible, results are presented in closed form.