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TY - CONF AU - Palczewski, A.D. AU - Gonnella, D. AU - Melnychuk, O.S. AU - Sergatskov, D.A. ED - Michel, Peter ED - Arnold, André ED - Schaa, Volker RW TI - Study of Flux Trapping Variability between Batches of Tokyo Denkai Niobium used for the LCLS-II Project and Subsequent 9-cell RF Loss Distribution between the Batches 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 - During the LCLS-II project a second batch of niobium was procured from Tokyo Denkai Co Ltd in order to make additional cavities. The original production material came from Two vendors Tokyo Denkai Co., Ltd. (TD) and Ningxia Orient Tantalum Industry Co., Ltd. (OTIC/NX)). It was found TD niobium required a lower annealing temperature (900°C) to obtain satisfactory flux expulsion characteristics compared to NX which required a slightly higher annealing temperature (950°-975°C). In order to ensure the new TD material performed equivalent to the niobium produced 4 year before after 900°C annealing; each heat lot of niobium had its flux expulsion characteristics parametrized and custom thermal treatments developed for each lot. Subsequent pure heat lot 9 cell cavities were made and tested. We will look at the flux expulsion characteristics of each lot, and RF loss of the 9-cell cavities produced using the individual heat lots. PB - JACoW Publishing CP - Geneva, Switzerland SP - 570 EP - 575 KW - cavity KW - niobium KW - SRF KW - FEL KW - superconductivity DA - 2019/08 PY - 2019 SN - "" SN - 978-3-95450-211-0 DO - doi:10.18429/JACoW-SRF2019-TUP057 UR - http://jacow.org/srf2019/papers/tup057.pdf ER -