Electrical breakdown characteristics of ozonized water treated oxygen-free copper electrodes in a vacuum and their surface conditions

The in¯uence of ozonized water treatment on the conditioning effect of a vacuum gap was investigated by applying impulse voltages. With regard to a 30 min treatment, the breakdown ®eld improved from 37.6 MV/m at ®rst voltage application to 261 MV/m after 500 breakdowns. This conditioned breakdown ®eld was lowered to 27.0 MV/m when the electrodes were exposed to air for 3 weeks. Reconditioning, however, was rapidly achieved, and the value was as high as that before being exposed to air. The electrodes exposed to air for 2 months after reconditioning showed similar results to that of those exposed to air for 3 weeks. # 2001 Elsevier Science B.V. All rights reserved