Vacuum breakdown characteristics for stainless steel electrode and influence of contamination degree of the electrode surface on the breakdown characteristics

In this paper, we reported vacuum breakdown characteristics for some kinds of stainless steel electrodes, for example, SUS304, SUS304L, SUS316, SUS316L, SUS310, SUS321 which are stainless steel alloy of different component ratio. These electrodes have different contamination degree on the surface. The contamination degree of the electrode surface is analyzed by the XPS (X-ray Photoelectron Spectroscopy). We investigated the correlation between the contamination degree and breakdown characteristics. Experimental results revealed that the degree of the carbon contamination of the electrodes gave rise to a certain degradation of the saturated breakdown field and the increase of the number of spark conditioning breakdowns to achieve the saturated breakdown field. The electrochemical polishing technique for the stainless steel electrode was effective in the improvement of vacuum breakdown characteristics. According to XPS spectrum for the electrode surface before breakdown test, the process of the electrochemical polishing reduced the carbon contamination. It was found that the saturated breakdown fields after spark conditioning and conditioning speeds had a relation to the degree of contamination for carbon.