High-Speed Spectroscopy of Vacuum Breakdown Process between CuCr Electrode

In the dielectric breakdown process in vacuum, plasma flare initiated on cathode and/or anode surfaces expands and collides. The plasma flare behavior is quite important for the optimization of the spark conditioning in vacuum circuit breakers. Copper-chromium is widely used as electrode materials in large-capacity vacuum circuit breakers. In this study, high-speed spectroscopy was conducted on the plasma flares between CuCr(Cr-35wt%)-anode and Cu-cathode in order to elucidate the plasma temperature and particle composition in the plasma flare. As a result, it was found that the plasma temperature was about 13000 K and the mixing ratio
$\boldsymbol{n}_{\mathbf{Cu}}/(\boldsymbol{n}_{\mathbf{Cu}}+\boldsymbol{n}_{\mathbf{Cr}})$
was 60–70%, which is almost the same as that of the anode material composition.