Systematic Comparison of Vacuum Arc between CuCr and AgWC Electrode by Using Various Optical Technique

Interelectrode phenomena related to intense-mode vacuum arc interruption were systematically compared between CuCr and AgWC electrodes, by using various optical techniques mainly including a Shack-Hartmann method for simultaneous two-dimensional electron and metal vapor density imaging and two-color pyrometry for anode temperature determination after current zero. During the arc period, the electron density for the CuCr was several times higher than that for the AgWC. On the other hand, the metal vapor density for the CuCr was lower than the AgWC during and after the arcing time. The decaying time constants of the metal vapor densities agreed well with those of the anode evaporation speed estimated from the anode temperature measurement. This means that the metal vapor after the intense vacuum arc interruption was not the residual metal medium originating from the arc phase and the supplying process of the metal vapor was the evaporation of anodes.