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SRF2003 Show Abstract

Title Development of Hydrogen-free EP and Hydrogen absorption phenomena
Type Talk  
Abstract We developed a hydrogen-free electropolishing (EP) method for superconducting niobium RF cavities in KEK. By this method one can eliminate necessity for any kind of annealing. Since TRISTAN project we applied the combination of mechanical grinding and EP to have high gradient performance reliably. In such process, annealing process was inevitable to eliminate the hydrogen Q-disease problem. This annealing is time-consuming and pushes the preparation cost up. For a large scale production like TESLA, this process should be omitted if possible for the cost-effective production. We searched for such possibility and finally innovated a hydrogen-free preparation method without annealing. We found hydrogen absorption occurs because of the water during the wet mechanical grinding like barrel polishing. We succeeded to prevent hydrogen absorption in barrel polishing replacing the water by a liquid without hydrogen component. Later we found that such hydrogen-free barrel polishing was not sufficient, because hydrogen is picked up during the successive EP.    We found a stationary oxidation process like in chemical polishing prevents this hydrogen problem to occur. Thus we finally invented the hydrogen-free electropolishing by putting one drop of nitric acid into the EP acid.

List of authors...

Principle author first.

Last (Family) Name First Name (Initials only) Affiliation or Organization (abbreviations if possible)
Higuchi T. Grad. Univ. Advanced Studies
Saito K. KEK, Accelerator Laboratory

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