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TY - CONF AU - Sulimov, A. AU - Gresele, A. AU - Navitski, A. AU - Palczewski, A.D. AU - Thie, J.H. ED - Michel, Peter ED - Arnold, André ED - Schaa, Volker RW TI - Experience of LCLS-II Cavities Radial Tuning at DESY J2 - Proc. of SRF2019, Dresden, Germany, 30 June-05 July 2019 CY - Dresden, Germany T2 - International Conference on RF Superconductivity T3 - 19 LA - english AB - Radial tuning (rolling) was applied to three LCLS-II cavities to prevent that their lengths exceed the technical limits. The cavities have a reduced frequency due to additional material removal during cavity treatment well beyond the baseline recipe. The mechanical condition of the cavities was relatively soft because of the thermal history and the niobium manufacture requirement of an optimal flux expulsion. The niobium was highly recrystallized by 3 hours annealing at 900°C and 975°C respectively. Each cavity received an inner surface treatment of 200 µm electro-polishing (EP) and an external 30 µm buffered chemical polishing (BCP) as part of the baseline recipe. Each cavity received an addition ~100 µm of chemical removal along with a second annealing treatment before the radial tuning process. Detailed information about the accuracy and homogeneity of LCLS-II cavities rolling is presented as well as results of field distribution analysis for TM011 zero-mode with a comparison to standard cavities. PB - JACoW Publishing CP - Geneva, Switzerland SP - 456 EP - 458 KW - cavity KW - HOM KW - SRF KW - FEL KW - linac DA - 2019/08 PY - 2019 SN - "" SN - 978-3-95450-211-0 DO - doi:10.18429/JACoW-SRF2019-TUP023 UR - http://jacow.org/srf2019/papers/tup023.pdf ER -