Photoinduced field-assisted electron emission from dielectric-coated electrodes into gases

Abstract

A photoinduced non-self-sustained discharge in a point–plane gap at near-atmospheric pressures in nitrogen and nitrogen–oxygen mixture was studied. Molybdenum and platinum points were coated with thin layers of MgO and TiO2 of different thicknesses. Static current–voltage characteristics were recorded at different intensities of triggering light, layer thickness and gas pressure. The common regularities of current–voltage characteristics were independent of the electrode/coating combinations used. The studies showed that the field-assisted two-step model of emission describes the experimental findings. The electron emission is controlled by Schottky and Fowler–Nordheim mechanisms at the metal–dielectric interface and by a recombination of positive ions with ‘hot’ and free electrons near the dielectric–gas interface.