Observation of Pulse Current Occurring during Spark Conditioning Process of a Vacuum Gap

Abstract

  It is known that the hold-off voltages of vacuum gaps can be improved by the spark conditioning with repetitive electrical breakdowns. At the initial stage of spark conditioning process, small pulse currents (not breakdowns) were observed, and in turn hold-off voltages were improved. To clarify the generating mechanism of the pulse current and the reason of the improvement in hold-off voltages, repetitive pulse current was generated, and chemical compositions of the electrodes were analyzed before and after experiments. The analysis of chemical compositions was carried out by a X-ray photoelectron spectroscopy (XPS). The XPS analysis revealed that only the anode surface was cleaned by repetitive pulse current flowing. This result suggests that cleaning the anode surface by repetitive pulse current flowing would be one of causes of the improvement in hold-off voltages of a vacuum gap at the initial stage of conditioning process.