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TY - CONF AU - Luo, D. AU - Metzgar, E.S. AU - Nakajima, T. AU - Nasu, I. AU - Popielarski, L. AU - Saito, K. AU - Shanab, S.M. AU - Simpson, G.V. AU - Taguchi, J. ED - Yamazaki, Yoshishige ED - Raubenheimer, Tor ED - McCausey, Amy ED - Schaa, Volker RW TI - Analysis of High Field Q-Slope (HFQS) Causes and Development of New Chemical Polishing Acid J2 - Proc. of NAPAC2019, Lansing, MI, USA, 01-06 September 2019 CY - Lansing, MI, USA T2 - North American Particle Accelerator Conference T3 - 4 LA - english AB - In our previous studies of High Field Q-slope (HFQS) we have concluded that nitrogen contamination from the nitric acid is the main cause of the degradation of the Q in buffered chemical polished cavities. Our conclusion is made based on previously unresolved phenomena which are found from huge amount of published cavity test data, include fine grain, large grain and single crystal cavities treated with EP and BCP. According to this analysis, we have started developing new nitrogen-free chemical polishing acid. Hydrogen peroxide with HF mixture was reported able to react with Nb, and there’s no extra element contamination in it, so we replace the conventional BCP with this mixture to start our study. In this paper, some Nb coupon sample results with new acid will be reported. We complete the first step of developing the new acid and we got the Nb finish roughness no worse than conventional BCP. PB - JACoW Publishing CP - Geneva, Switzerland SP - 699 EP - 702 KW - cavity KW - SRF KW - experiment KW - superconductivity KW - niobium DA - 2019/10 PY - 2019 SN - 2673-7000 SN - 978-3-95450-223-3 DO - doi:10.18429/JACoW-NAPAC2019-WEPLM47 UR - http://jacow.org/napac2019/papers/weplm47.pdf ER -