Author: Eschke, J.
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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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TUPTEV011 SRF Accelerating Modules Repair at DESY 508
  • D. Kostin, J. Eschke, K. Jensch, N. Krupka, L. Lilje, A. Muhs, D. Reschke, S. Saegebarth, J. Schaffran, M. Schalwat, P. Schilling, M. Schmökel, S. Sievers, N. Steinhau-Kühl, E. Vogel, H. Weise, M. Wiencek, B. van der Horst
    DESY, Hamburg, Germany
  Eight SRF cavities assembled in an accelerating module represent a building block of the particle linear accelerator based on TESLA SRF technology. DESY has two machines, European XFEL and FLASH. Both use almost same module and cavity types. During the module assembly many factors can deteriorate the cavity performance and cause a need for a repair action. Currently two European XFEL modules and two FLASH ones underwent reassembly procedures. The repair was not immediately successful on every of these modules and re-iterations did follow. The degradation causes were investigated. SRF modules were tested on both test-stands at DESY: AMTF and CMTB. The results of the described actions are presented and discussed.  
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About • Received ※ 18 June 2021 — Accepted ※ 19 November 2021 — Issue date; ※ 01 February 2022  
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