Influence of the material nature (Ag, Cu, Al, W, C) on the arc root characteristics at the cathode

This paper describes a thermo physical phenomena analysis about a silver, copper, aluminium, iron, tungsten or graphite electrode submitted to a high density energy flux. The thermal flux necessary to create a cathode spot is about 1.10¹²Wm^-2. For the studied metals and for values lower than 1.10¹² Wm^-2, the liquid phase does not appears and the entire energy coming at the cathode surface diffuses in the electrode. For values upper than 5.10¹² Wm^-2 a large part of the energy is used for the vaporization and the electrode vaporized length depends of the material nature. The gap situated between the two extreme values 1.10^{11 W m-2 and 1.1013 Wm-2 corresponds to the cathode spot with liquid and vapour phases.}