Author: Eschke, J.
Paper Title Page
TUPO029 Highlights of the XM-3 Cryomodule Tests at DESY 388
 
  • J. Branlard, V. Ayvazyan, A. Bellandi, J. Eschke, C. Gumus, D. Kostin, K.P. Przygoda, H. Schlarb, J.K. Sekutowicz
    DESY, Hamburg, Germany
  • W. Cichalewski
    TUL-DMCS, Łódź, Poland
 
  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.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO029  
About • paper received ※ 11 September 2018      issue date ※ 18 January 2019  
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