Modeling of the Influence of Temperature on the Emission Properties of a Cathode with a Thin Insulating Film in a Glow Gas Discharge and the Discharge Voltage–Current Characteristic

A model of glow gas discharge in the presence of a thin insulating film on the cathode is formulated. It takes into account that under discharge current flow, due to the bombardment of the cathode by ions, positive charges accumulate on the film and generate strong electric field in it. As a result, field emission of electrons from the cathode metal substrate into the film starts, which, with an increase in its temperature, transforms into thermal-field emission. Electrons move in the film, being accelerated by the electric field and decelerated in collisions with phonons, and some of them leave the film into the discharge, increasing the effective ion-electron emission yield of the cathode. The electric field strength in the film is determined from the condition that the density of the discharge current and the density of the emission current from the cathode metal substrate into the film are equal. The dependences of the film emission efficiency, the effective ion-electron emission yield of the cathode, and the discharge characteristics on the cathode temperature are calculated. It is shown that already at a temperature exceeding room temperature by several hundred degrees, the temperature enhancement of field electron emission from the metal substrate into the film can noticeably influence the cathode emission properties and the discharge voltage-current characteristic.