Electrical Breakdown in a Cold Cathode Vacuum Diode

A 50-ns pulse generator is used to obtain time-correlated current-voltage relationships in the prebreakdown region for a long vacuum gap with cold planar electrodes. Analysis of data indicates several sequential stages occur. These stages include an initial quiet stage of voltage increase without interelectrode current, a microdischarge stage, a field emission stage, a space-charge controlled stage, and a final low-impedance stage where the current becomes sustaining. Electrical breakdown of the gap is considered in terms of a positive ion front moving from the anode.