Arc Spot on Film Cathode using Kinetic Approach of Plasma Flow

A physical model of spot operation on film cathodes was developed and a system of equations was derived to understand Kesaev’s measurements of spot parameters on Cu films of 0.017 to 0.14 μm thickness deposited on glass substrates. Kinetics model of cathode vaporization was used to describe the spot phenomena. The plasma velocity normalized by the plasma sound speed is determined by the rate of film evaporation, dependent on the spot action. The power losses due to film heat conduction was calculated comparable with that power losses by vaporization. The calculations and measurements were comparable, in particular, for low cathode potential drop (~ 12 V).