Optical Emission Spectroscopy for Plasma Parameter Characterization of Vacuum Arc Cathode Spot

The cathode spot, which is the source of metal vapor and electrons, dominates the properties of vacuum arc discharges. However, the size of the cathode spot is so small that parameters such as excitation temperature, which indicate the internal state of the cathode spot, have rarely been measured. In this study, optical emission spectroscopy was conducted for the cathode spots with high spatial resolution. Using a CuCr alloy electrode with a small amount of Te, a low-melting-point metal, the excitation temperatures were experimentally determined with high measurement accuracy.