Author: Petersen, B.
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Fundamentals of Cryomodule Design and Cryogenics  
  • B. Petersen
    DESY, Hamburg, Germany
  Some considerations and specifications for cryomodule design are discussed for different accelerator applications. The cryomodule design as well as the layout of the cryogenic distribution scheme have to be adapted to the particular accelerator requirements. Disregarding the differences, the various cryomodule designs share several common fundamental features like thermal insulation and RF cavity alignment. Examples for cryomodule designs are shown with reference to the ESS and XFEL cryomodules. Some criteria for the choice of the superconducting cavity operation temperature are discussed. Fundamental elements of helium refrigerators are shown. In particular, different options for subatmospheric Helium II bath cooling are illustrated. The importance of Helium bath pressure stability for the RF operation of superconducting cavities is clarified. Some methods to adapt the refrigerator operation to RF load changes or to compensate the RF load changes are explained. The XFEL linac cryogenic system layout is presented as an example.  
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THP081 A Cryocooled Normal Conducting and Superconducting Hybrid CW RF Gun 1091
  • H.J. Qian, G. Shu, F. Stephan
    DESY Zeuthen, Zeuthen, Germany
  • S. Barbanotti, B. Petersen, E. Vogel
    DESY, Hamburg, Germany
  • A.A. Gorchakov, M. Gusarova
    MEPhI, Moscow, Russia
  Continuous wave (CW) photoinjectors have seen great progress in the last decades, such as DC gun, superconducting RF (SRF) gun and normal conducting (NC) gun. Developments of Free electron lasers and electron microscopy in the CW mode are pushing for further improvements of CW guns towards higher acceleration gradient, higher beam energy and compatibility with high QE cathodes for better beam brightness. Current SC gun gradient is limited by the cathode cell due to the complication of a cathode back plane and a normal conducting cathode plug, and R&D on SC gun improvement is ongoing. A high gradient cryocooled CW NC gun was proposed to house the high QE cathode, and a SC cavity immediately nearby gives further energy acceleration. In this paper, further RF optimization of the NC gun and ASTRA simulations of such a hybrid photoinjector are presented.  
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About • paper received ※ 25 June 2019       paper accepted ※ 03 July 2019       issue date ※ 14 August 2019  
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