Energy conditioning and barium contamination effects in low pressure breakdown to 300 KV

Electrical breakdown at low pressures (<;10^-5 torr) depends critically upon prior conditioning of the electrode surfaces. The discharge energy is a factor of major importance, with high energy discharges producing low and erratic breakdown voltages. In addition, under high energy discharge conditions anode material becomes a dominant factor, with the more refractory metals (such as Ti, SS, or Ni) capable of significantly better performance than the less refractory metals (such as AI, Cu, or Pb). The breakdown voltage in this case correlates closely with physical properties of the anode material-melting point, specific heat, and density.