Author: Navitski, A.
Paper Title Page
TUP023 Experience of LCLS-II Cavities Radial Tuning at DESY 456
  • A. Sulimov, J.H. Thie
    DESY, Hamburg, Germany
  • A. Gresele
    Ettore Zanon S.p.A., Nuclear Division, Schio, Italy
  • A. Navitski
    RI Research Instruments GmbH, Bergisch Gladbach, Germany
  • A.D. Palczewski
    JLab, Newport News, Virginia, USA
  Radial tuning (rolling) was applied to three LCLS-II cavities to prevent that their lengths exceed the technical limits. The cavities have a reduced frequency due to additional material removal during cavity treatment well beyond the baseline recipe. The mechanical condition of the cavities was relatively soft because of the thermal history and the niobium manufacture requirement of an optimal flux expulsion. The niobium was highly recrystallized by 3 hours annealing at 900°C and 975°C respectively. Each cavity received an inner surface treatment of 200 µm electro-polishing (EP) and an external 30 µm buffered chemical polishing (BCP) as part of the baseline recipe. Each cavity received an addition ~100 µm of chemical removal along with a second annealing treatment before the radial tuning process. Detailed information about the accuracy and homogeneity of LCLS-II cavities rolling is presented as well as results of field distribution analysis for TM011 zero-mode with a comparison to standard cavities.  
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About • paper received ※ 23 June 2019       paper accepted ※ 01 July 2019       issue date ※ 14 August 2019  
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