Vacuum breakdown characteristics of oxygen-free copper electrodes with different keeping methods and terms

It has been known that the performance of hold-off voltage of vacuum breakdown for electrodes strongly depends on the surface contamination. Therefore, after manufacturing and cleaning of the electrodes, it is important to handle and keep them under clean condition until the use of them. In order to investigate the influence of keeping methods and terms on the vacuum breakdown characteristics of oxygen-free copper electrode, we focused on keeping method and terms of electrodes. Electrodes used for test were kept in atmosphere, in nitrogen and in vacuum for a specific term. Repetitive breakdown tests and the XPS surface analysis before and after repetitive breakdown tests were carried out in vacuum to investigate. Experiment results revealed that the degree of the contamination and the oxidation of test electrode surfaces made some degradation of the breakdown electric field and increased the necessary number of repetitive breakdown to achieve conditioning.