Initiation Process of Vacuum Breakdown Between Cu and CuCr Electrodes

During the breakdown process in a vacuum, plasma flares initiated on cathode and anode surfaces expand and collide. The plasma flare behavior is quite important for the optimization of the spark conditioning of vacuum interrupters. Here, copper- chromium alloys are widely used as an electrode material in the large-capacity vacuum circuit breakers. In this article, highspeed spectroscopy is conducted on the plasma flares generated between a CuCr (Cr-35wt%) anode and a Cu cathode in order to elucidate the plasma temperature, particle composition, and electron density. The experimental results show that the anode flare has 10
²⁴
-10
²⁵
m
^-3
electron, and its temperature is approximately 13000 K. The composition ratio of vapor atoms consisting the anode flare is Cu:Cr = 6:4-7:3, which is almost the same with that of anode material composition.