Explanation of the quasi-harmonic field emission behaviour observed on epoxy-coated polymer graphite cathodes

In this paper, a new theory is presented to explain the effects of polymer-coated cathodes based on an experiment. Experimental data were obtained by measuring the total emission current from the tip of an electrochemically etched polymer graphite rod, which acts as a disordered array of emission cathodes. Based on the presented experimental results (mainly the time-current characteristics at fixed voltage values), a physical model including an equivalent circuit is presented in this paper to describe its quasi-harmonic behaviour based on the effects of periodic charging and discharging. Explanations of desirable effects such as current stabilization or threshold voltage drop, all of which are due to the dielectric coating and which were previously reported on a single tip, are addressed and put in context with previous results presented by several authors. Finally, based on experimental findings, a possible application of such a pulsing structure towards vacuum devices using emission current is proposed.