Analysis of the Anomalous High-Current Cathode Emission in Pseudo-spark and Back-of-the-Cathode Lighted Thyratron Switches.

摘要

An analysis of the anomalously large cathode emission recently observed in the superdense glow of pseudo-spark are low-pressure (27 Pa H2) glow discharge pulsed power devices. After operating at peak discharge currents of 6 - 8 kA and pulse durations of 0.5 - 1 microsec, the surface surrounding the cathode hold was found to have been homogeneously melted within a radius of approx 4 mm indicating that the discharge is a superdense glow discharge, not an arc, with a cross-sectional area on the order of 1 sq. cm. This conclusion is also supported by streak camera measurements. The current density at the cathode surface under these conditions is 5 - 10 kA/sq cm, several orders of magnitude larger than that of thermionic cathodes in common thyratrons. This high is from a high current density ion beam produced in the cathode fall during the initial stage of current buildup. The surface heating resulting from this 'beam' yields a significant field-enhanced thermionic emissions of electrons. Reprints. (RRH)