Microdischarges in diodes with small gaps and field emission glassy carbon cathodes

Abstract

We report on the results of experimental investigation of microdischarges in diodes with small gaps and glassy carbon field-emission cathodes. It is shown that microdischarges in diodes with multipoint cathodes are initiated and evolve at the tips of micropoints when the field-emission current density attains the critical values in accordance with the Dyke theory. The field-emission current density in diodes with a developed surface without micropoints does not attain critical values and does not trigger microdischarges. It has been established experimentally that for diode gaps smaller than 100 µm, the change in the residual gas pressure from 1 × 10–7 to 1 × 10–5 Torr does not affect the emissivity and stability of field emission from glassy carbon cathodes. The threshold field strength at which microdischarges are initiated in diodes with glassy carbon cathodes remains unchanged in the residual gas pressure range from 1 × 10–7 to 1 × 10–5 Torr.