Correlation between cathode properties, burning voltage, and plasma parameters of vacuum arcs

Burning voltages of vacuum arcs were measured for 54 cathode materials and compared with literature data. As anticipated, a correlation between the arc burning voltage and the plasma temperature was found. However, more importantly, a correlation between the cohesive energy of the cathode material and the arc burning voltage could be demonstrated. This link between a cathode material property, the cohesive energy, and a discharge property, the arc burning voltage, is essential for the operation of the vacuum arc discharge because is determines the plasma temperature. Energy balance considerations show that this “cohesive energy rule” is responsible for several other secondary relationships, such as the correlation between the mean ion charge state and the boiling temperature of the cathode.