HIGH VOLTAGE BREAKDOWN STUDY

Statistical and physical analyses of the block of eight experiments were carried out for unconditioned gaps and for conditioned gaps with and without perpendicular magnetic field. The other factors examined were anode and cathode treatment vacuum or hydrogen firing and electrode size. Prebreakdown current and breakdown voltage values were examined in the statistical analysis. Second order and higher order interactions were found to be important in addition to main factor effects. The magnetic field significantly affected the breakdown voltage and also interacted with other factors. The theoretical model of the breakdown mechanism developed was consistent with the results and trends of the statistical analysis. The 300 kv apparatus was disassembled for complete overhaul, cleaning and remachining. This included electropolishing of the vacuum chamber and polishing of all gold O-ring surfaces. The box heating oven was replaced with a form fitting as heater blanket unit and the controls for both and the electrode heaters were made completely automatic. The latter have now been removed from the vacuum envelope and the complete system has been reassembled, baked and made vacuum tight. Author