Author: Hellert, T.
Paper Title Page
WEPG03 HOM Characterization for Beam Diagnostics at the European XFEL Injector 616
  • N. Baboi, T. Hellert, L. Shi, T. Wamsat
    DESY, Hamburg, Germany
  • R.M. Jones, N.Y. Joshi, L. Shi
    UMAN, Manchester, United Kingdom
  • N.Y. Joshi
    University of Manchester, Manchester, United Kingdom
  Funding: The work is part of EuCARD-2, partly funded by the European Commission, GA 31245.
Higher Order Modes (HOM) excited by bunched elec-tron beams in accelerating cavities carry information about the beam position and phase. This principle is used at the FLASH facility, at DESY, for beam position monitoring in 1.3 and 3.9 GHz cavities. Dipole modes, which depend on the beam offset, are used. Similar monitors are now under design for the European XFEL. In addition to beam position, the beam phase with respect to the accelerating RF will be monitored using monopole modes from the first higher order monopole band. The HOM signals are available from two couplers installed on each cavity. Their monitoring will allow the on-line tracking of the phase stability over time, and we anticipate that it will improve the stability of the facility. As part of the monitor designing, the HOM spectra in the cavities of the 1.3 and 3.9 GHz cryo-modules installed in the European XFEL injector have been measured. This paper will present their dependence on the beam position. The variation in the modal distribution from cavity to cavity will be discussed. Based on the results, initial phase measurements based on a fast oscilloscope have been made.
poster icon Poster WEPG03 [3.281 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG03  
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