Cathode sheath model of a vacuum arc with a nonmonotonic potential profile in the plasma near the cathode

A physical model is presented for the cathode sheath of a vacuum arc with vaporizing cathode. The model is based on the idea that the potential has a local minimum at the external boundary of the cathode sheath. For a prescribed heat release and current density at the cathode the model allows the cathode potential drop, the cathode temperature, the electron temperature in the plasma, and the rate of cathode vaporization to be determined. Calculations are performed of the cathode sheath parameters for an arc with a current density 10-100 A/cm{sup 2} struck in gadolinium, chromium, and titanium vapors. Satisfactory agreement is obtained with available experimental data. 21 refs., 6 figs., 2 tabs.