H.INO*, K.TAJIRI*, Z.KABEYA*, T.NAKAMURA**, Y.YAMANAKA**, K.YOSHINO***, F.NAITO***, T.KATO***, E.TAKASAKI***, Y.YAMAZAKI***
We developed a pure copper lining process for RF cavities using a new copper electroforming, an periodic reverse copper electroforming with a low Cu-content acid copper sulfate bath which contains no organic additives (PR process ). The PR process offers pure copper that contains impurities less than 35 ppm or so, and that has equivalent IACSEiInternational Annealed Copper StandardEjvalue to that of oxygen-free wrought copper. The lining process can be applied to complex accelerator components. As the PR process does not provide smooth surface required, we machined the electroformed copper surface to the roughness of 3S. Then, it was electropolished in an aqueous solution of phosphoric acid and chromic acid. The polished surface, after removing 4/100 mm in thickness, was smoother than the plated surface of a conventional lining, and the surface showed no crystal boundaries in appearance. We produced the trial model of DTL (drift
 K. Tajiri and T. Imamura, Proceeding Volume 99-1 of the 195th Meeting of The Electrochemical Society, Abstract No.102, (1999).
*Mitsubishi Heavy Industries, Ltd. Nagoya Aerospace Systems, 10, Oye-cyo, Minato-ku, Nagoya 455-8515 Japan
**Asahi Kinzoku Kogyo Co. Ltd., 4851-4, Maki, Anpachi-cyo, Anpachi-gun, 503-0125 Japan
***KEK-High Energy Accelerator Research Organization, 1-1, Oho, Tsukuba, 305-0801 Japan
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