A model of the cathode spot glow discharge for a cathode with inclusions of low work function material

A model that describes the self-maintained glow discharge for a composite cathode in which cathode spots are formed on low work function material inclusions is presented. Based on this model, expressions are obtained for the radius of the spot, the cathode voltage, and the spot current as functions of Pd (where P is the gas pressure and d is the thickness of the cathode layer), the parameters of the inclusions, and the basic material matrix are obtained. Numerical results for the case of a glow discharge in 75 torr neon gas with a copper cathode matrix and inclusions of LaB₆ are presented. The average radii of inclusions were 0.05 and 0.015 mm. Conditions under which the glow discharge migrates from the inclusions and begins to spread onto the surface of the basic matrix are obtained. The transition of the glow discharge into a contracted state, depending on the structure of the composite material, is also considered