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TY - CONF AU - Branlard, J. AU - Ayvazyan, V. AU - Bellandi, A. AU - Cichalewski, W. AU - Eschke, J. AU - Gumus, C. AU - Kostin, D. AU - Przygoda, K.P. AU - Schlarb, H. AU - Sekutowicz, J.K. ED - Schaa, Volker RW ED - Pei, Guoxi ED - Chin, Yong Ho ED - Fu, Shinian ED - Zhao, Ning TI - Highlights of the XM-3 Cryomodule Tests at DESY J2 - Proc. of LINAC2018, Beijing, China, 16-21 September 2018 CY - Beijing, China T2 - Linear Accelerator Conference T3 - 29 LA - english AB - To investigate the feasibility of the continuous wave (cw) upgrade of the European XFEL (E-XFEL) DESY, on-going tests are performed on E-XFEL prototype and production cryomodules since 2011. For these studies, DESY’s Cryo-Module Test Bench (CMTB) has been equipped with a 10⁵ kW cw operating IOT in addition to the 10MW pulsed klystron, making CMTB a very flexible test stand, enabling both cw and pulse operation. For these tests, E-XFEL-like LLRF electronics is used to stabilize amplitude and phase of the voltage Vector Sum (VS) of all 8 cavities of the cryomodule under test. The cryomodule most often tested is the pre-series XM-3, unique since it is housing one fine grain niobium and seven large grain niobium cavities. In autumn 2017, additional spacers were installed on all 8 input couplers to increase the maximum reachable loaded quality factor Ql beyond 2·10⁷. With higher Ql, up to 6·10⁷ for 6 cavities and 2.7·10⁷ for 2 cavities, we have investigated the VS stability and SRF-performance of this cryomodule under various conditions of cooling down rate and operation temperature 1.65K, 1.8K and 2K, at gradients up to ca. 18MV/m. The results of these tests are presented in this paper. PB - JACoW Publishing CP - Geneva, Switzerland SP - 388 EP - 390 KW - cavity KW - cryomodule KW - FEL KW - operation KW - feedback DA - 2019/01 PY - 2019 SN - 2226-0366 SN - 978-3-95450-194-6 DO - DOI: 10.18429/JACoW-LINAC2018-TUPO029 UR - http://jacow.org/linac2018/papers/tupo029.pdf ER -