Author: Bellandi, A.
Paper Title Page
Overview of CW R&D With a European XFEL Cryomodule  
  • A. Bellandi, J. Branlard, J. Eschke, Ç. Gümüş, D. Kostin, R. Onken, J.K. Sekutowicz, E. Vogel
    DESY, Hamburg, Germany
  Since 2011 a research and development program is carried out at DESY to study the feasibility of a possible Continuous-Wave (CW) upgrade of the European X-ray Free Electron Laser (XFEL). Cryo-Module Test Bench (CMTB) is a test facility at DESY used to perform tests with accelerating modules equipped with TESLA-type superconducting cavities. In this proceeding, the most recent tests at CMTB on module XM50.1 are presented. For the European XFEL upgrade, a key-importance question to answer is the cryomodules’ heat load when driven in CW. Therefore, tests at accelerating gradients up to 19 MV/m per cavity at 2K were carried to determine the cavities’ dissipated power. Operating at QLs > 107 is also challenging for the LLRF: the narrow RF bandwidths involved require active online detuning disturbances rejection techniques. Therefore a new detuning estimator was developed. The estimator is also capable of working as a quench/multipacting detector. Tests on XM50.1 show that it is possible to estimate detuning disturbances with a sub-hertz precision and to catch multipacting events. Finally, the maximum achieved gradients with the module and after RF conditioning are presented.  
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