Measurement of Electrode Erosion during High-Voltage Vacuum Breakdown

This paper is concerned with the measurement of the mass of electrode material released by the electrodes during a high-vacuum breakdown. The techniques used in the experiment described in this paper for quantitative measurement of material released from the electrodes are neutron activation analysis and gamma-ray spectrometry. The method permits determination of the small masses released during the discharge. The threshold energy density required for material release is 15 J/mm2. An empirical equation is given for the material erosion for copper and a curve is given that relates mass erosion versus stored energy for copper electrodes. The experiment indicates that the mechanism responsible for current transport between the electrodes in a vacuum breakdown is a highly ionized plasma formed from the released electrode material.