IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Vacuum Science & Technology Monday Sessions
       Session VST-MoP

Paper VST-MoP15
Influence of Ozonized Water Treatment and Subsequent in situ Sputter Cleaning on Electrical Breakdown Characteristics of Oxygen-free Copper Electrodes of a Vacuum Gap

Monday, October 29, 2001, 5:30 pm, Room 134/135

Session: Developments in Vacuum Technology Poster Session
Presenter: S. Kobayashi, Saitama University, Japan
Authors: S. Kobayashi, Saitama University, Japan
K. Sekikawa, Saitama University, Japan
K. Asano, Akita National College of Technology, Japan
Y. Saito, High Energy Accelerator Research Organization, Japan
Correspondent: Click to Email
Electrical breakdown characteristics of a vacuum gap depend on the electrode surface conditions, since the breakdown can be initiated by emission of such particles as electrons, ions, gases or clumps. These particles are emitted from contaminant layers of electrode surfaces. To improve breakdown strength removal of contaminant layers is required. Ozonized water treatment is recognized as the process to make surface clean and passivated. It has been exhibited that ozonized water treated oxygen-free copper electrodes can achieve higher breakdown field (breakdown voltage/gap length) after repetitive breakdowns, while the improvement in the breakdown field at the first voltage application (the first breakdown field) is little.@footnote1@ Electrode suface analysis clarified that the surfaces are slightly contaminated after ozonized water treatment. It was therefore considered that this contamination might cause the first breakdown field stay at the similar level to that for the untreated electrodes. To confirm the effect of the recontamination after ozonized water treatment on the first breakdown field, breakdown fields of electrodes treated with ozonized water alone and treated with ozonized water followed by in situ He ion beam sputter cleaning were compared. Experiments revealed that the additional in situ sputter cleaning is much effective on the improvement in the first breakdown field and the value of the breakdown field achieves 74 MV/m (ozonized water treatment condition : concentration ; 4.8 ppm, treatment hour ; for 60 min), while the value for the electrode treated with ozonized water alone is 69 MV/m. Also revealed is the excellent conditioning effect, that is, after 500 repetitive breakdowns the breakdown field achieves the value of 269 MV/m at 0.3 mm gap length. This value corresponds to the fact that the voltage of about 80 kV can be applied to 0.3 mm gap.. @FootnoteText@ @footnote 1@K. Sekikawa, et al., Applied Surface Science, Vol. 169-170 (2001) pp. 695-699.