Investigation of the behaviours of cathode spot current density on plasma parameters in low-current vacuum arc

Abstract

In order to investigate current density affecting plasma parameters, the cathode spot model is performed. The cathode spot model assumes that the collisionless ion sheath and the singly ionized collisional plasmas are directly connected. It was found that current density increases with decreasing arc current. The dependent variables, cathode temperature, electron current fraction, plasma temperature, sheath voltage, plasma density and cathode electric field increased in accordance with the increase in current. Alternatively, the cathode spot radius is inversely dependent on current density. These plasma parameters are related to T-F emission and thermionic emission process. This cathode spot model of the present analysis which is used to investigate the cathode spot parameter in low-current vacuum arc may be valid for volatile materials.