Energy distributions of carriers formed in a prebreakdown vacuum gap

Abstract

The energy distributions of electrons and ions which are carriers of the pre-breakdown current, are measured for Cu and Al electrodes under a steady-state prebreakdown condition (applied voltage: DC 3 kV maximum). These profiles of energy distributions of electrons irradiating the anode are broad for both electrode materials. The spread extends across the upper half of the applied voltage, and includes two sharp peaks: the upper one due to high-energy electrons, equivalent to the applied voltage, and the lower one due to low-energy electrons (1-10 eV). The ion energy distributions measured at the cathode have peaks at high energies (corresponding to the applied voltage) and sometimes at low-energy positions (1-20 eV) as well. The implications for the carrier energy distribution and the carrier-forming mechanisms are discussed.