A generalized current density model for field, thermal, and photo-emission

Recently the possibility that the dispenser cathode can be used as a photocathode source generated interest: it has been shown that this cathode has quantum efficiencies at least a factor of two better than the best metal cathode. The possibility of developing such a dispenser photocathode entails theoretical problems in a description of the emission process, which we address herein. The methodology is readily extended to high temperature/high field conditions and circumstances where the image charge contribution to the surface-vacuum barrier (or interface barrier in the case of transport between differing materials, as in wide bandgap emitters) is reduced or eliminated.