• A.T. Wu, G. Ciovati, R. Manus, C.E. Reece, R.A. Rimmer, J.S. Williams
  JLAB, Newport News, Virginia
• F. Eozénou
  CEA, Gif-sur-Yvette
• S. Jin, L. Lin, X.Y. Lu
  PKU/IHIP, Beijing
• J. Mammosser
  ORNL, Oak Ridge, Tennessee
• E. Wang
  BNL, Upton, Long Island, New York

Buffered electropolishing (BEP) is a Nb surface treatment technique developed at Jefferson Lab1. Experimental results obtained from flat Nb samples show2-4 that BEP can produce a surface finish much smoother than that produced by the conventional electropolishing (EP), while Nb removal rate can be as high as 4.67 μm/min. This new technique has been applied to the treatments of Nb SRF single cell cavity employing a vertical polishing system5 constructed at JLab as well as a horizontal polishing system at CEA Saclay. Preliminary results show that the accelerating gradient can reach 32 MV/m for a large grain cavity and 26.7 MV/m for a regular grain cavity. In this presentation, the latest progresses from the international collaboration between Peking University, CEA Saclay, and JLab on BEP will be summarized.