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TY - CONF AU - Éozénou, F. AU - Baudrier, M. AU - Cenni, E. AU - Fayette, E. AU - Hayano, H. AU - Ida, Y.I. AU - Ito, H. AU - Jullien, G. AU - Kato, S. AU - Kubo, T. AU - Maurice, L. AU - Monjushiro, H. AU - Nii, K. AU - Saeki, T. AU - Servouin, C. AU - Yamaguchi, T.Y. ED - McIntosh, Peter ED - Burt, Graeme ED - Apsimon, Robert ED - Schaa, Volker R.W. TI - Vertical Electro-Polishing of 704 MHz Resonators Using Ninja Cathode: Gradients Over 40 MV/m Achieved on ESS Single-Cell Cavity J2 - Proc. of LINAC2022, Liverpool, UK, 28 August-02 September 2022 CY - Liverpool, UK T2 - International Linear Accelerator Conference T3 - 31 LA - english AB - CEA, KEK and Marui Galvanizing Company have been collaborating to apply the Vertical Electropolishing (VEP) process of elliptical SRF cavities to a 704MHz single-cell ESS-type cavity, using a rotating so called and patented "Ninja" cathode. First presented results* were promising with a gradient of 27MV/m achieved, without any heat treatment applied. The performance has been pushed further since. The cavity has undergone a heat treatment at 650°C during 10h, followed by a final VEP sequence and a baking at 120°C during 48h hours. The achieved gradient at 2K was 44MV/m (power limitation), and the quality factor Q₀ exceeding 5·10¹⁰ up to 10 MV/m. The superiority of VEP compared to standard "BCP" chemical treatment is demonstrated and we intend now to scale the process to 5-Cell β=0.86 ESS cavity. We also intend to push further the performance by applying "2-step baking" (75°C and 120°C) proposed by FNAL, which was successfully applied at CEA Saclay on 1300MHz single-cell resonators with gradients above 50MV/m achieved after VEP bulk treatment. PB - JACoW Publishing CP - Geneva, Switzerland SP - 844 EP - 847 KW - cavity KW - cathode KW - niobium KW - SRF KW - linac DA - 2022/09 PY - 2022 SN - 2226-0366 SN - 978-3-95450-215-8 DO - doi:10.18429/JACoW-LINAC2022-THPOGE23 UR - https://jacow.org/linac2022/papers/thpoge23.pdf ER -