Prebreakdown current dependency on size and configuration of electrode pores

Studies of processes in pores of electrode surface were defined by two problems: 1) to suppress these processes in order to increase electrical strength of vacuum gap [1]; 2) to develop charged particle source with cold cathode based on these processes [2]. From the above references follows that at electrical field "strength values achieved in contemporary high voltage electron vacuum devices and electrophysical facilities prebreakdown currents, microdischarges and vacuum breakdown are defined by processes in micropores of electrodes (or the like defects). These processes are nothing but various stages of self-sustaining gas discharge development the final one being formation of cathode part over the surface of the pore. Voltage-current characteristics (VCCs) of prebreakdown currents attributed to processes in pores include linear and exponential parts. Line-to-exponent transition is defined, first of all, by vacuum, gap width and pore size, i.e., by degree of sagging of electrical field into the pore volume. More precisely, electrical field pattern depends on pore geometrical size relation, pore-depth-to-vacuum-gap-width ratio. To the greater extent this dependence is observed pore size being close to vacuum gap width. Pore configuration variation for the same pore size on electrode plane also defines voltage-current characteristics\´ exponential part appearance, i.e., vacuum gap breakdown. Creating special porous surface one can vary the electrical strength of vacuum insulation.