• S. Kato, M. Nishiwaki
  KEK, Ibaraki
• S. Azuma, F. Yamamoto
  Ultra Finish Technology Co., Ltd., Yokosuka
• P.V. Tyagi
  Sokendai, Ibaraki

Niobium electropolishing for SRF cavities are generally considered to be the best technology today. However, hydrofluoric and sulphuric acid mixture usually used in the EP process is harmful and requires us carefully controlled handling of it and the many additional facilities. In this article, we propose a new application of electrochemical buffing onto niobium SRF cavity. In the method of electrochemical buffing, a rotating disk with abrasive fine particles where electrolyte is supplied is pressed against the workpiece. The disk and the work function as a cathode and an anode, respectively and an aqueous solution of sodium nitrate is used for the electrolyte. This technique brings us a couple of advantages like high etching rate, ultra small surface roughness, cost-effective and environment-compatible polishing.