Spectroscopic Measurement and Analysis of High-Current Vacuum Arc near Copper Cathode

A spectroscopic measurement is performed of a 10-kA peak (kAp) vacuum arc in the vicinity of the 30-mm diameter cathode spaced 4 mm apart from the 60-mm anode. The electron temperature is determined from the Boltzmann distribution temperature of Cu II system by assuming the partial local thermodynamic equilibrium (PLTE). The electron temperature varies with the instantaneous arc current, and the radial electron temperature profile is peaked at the center of the arc discharge. It is shown that the arc is the diffuse discharge by comparing the calculated result of the effective arc resistance with the value previously measured in the diffuse arcs. In conclusion, the radial current density profile proves to be concentrated toward the center of the diffuse arc discharge near the cathode.