Plasma‐induced field emission and the characteristics of high‐current relativistic electron flow

摘要

The results of a comprehensive diode study conducted using a pulsed high‐current electron accelerator are reported. Time‐dependent analysis of right‐cylindrical graphite cathodes has shown evidence of the field emission character of the cold‐cathode diode. The effects of cathode whiskers or microprojections on the diode response have been observed. Within a few nanoseconds after the voltage is applied to the diode, the whiskers explode to form cathode flares. The observed diode perveance throughout the remainder of the pulse can be explained in terms of the expansion of the plasma cathode formed by the merger of many cathode flares. Cathode plasma velocities ranged from approximately 2 to 3 cm/mgr;sec. The observed diode behavior was consistent with that predicted by previous studies of high‐voltage vacuum breakdown.