Author: Lipka, D.
Paper Title Page
WEPC21 Design and Beam Test Results of Button BPMs for the European XFEL 723
  • D.M. Treyer, R. Baldinger, R. Ditter, B. Keil, W. Koprek, G. Marinkovic, M. Roggli
    PSI, Villigen PSI, Switzerland
  • D. Lipka, D. Nölle, S. Vilcins
    DESY, Hamburg, Germany
  Funding: Swiss State Secretariat for Education, Research and Innovation
The European X-ray Free Electron Laser (E-XFEL) will use a total ~300 button BPMs along the whole accelerator, as well as 160 cavity BPMs. The pickups for the button BPMs have been designed by DESY, whereas the electronics has been developed by PSI. This paper gives an overview of the button BPM system, with focus on the RF front end electronics, signal processing, and overall system performance. Measurement results achieved with prototypes installed at FLASH/DESY and at the SwissFEL Injector Test Facility (SITF) are presented. The position noise obtained with button pickups in a 40.5 mm aperture beam pipe is as low as ~11 um at 20 pC bunch charge.
poster icon Poster WEPC21 [1.595 MB]  
WEPF25 Resonator for Charge Measurement at REGAE 872
  • D. Lipka, J. Lund-Nielsen, M. Seebach
    DESY, Hamburg, Germany
  A resonator has been developed for the diagnostics of dark current and charge measurements at the European XFEL, FLASH and PITZ. The first induced monopole mode TM01 at 1.3 GHz from charged bunches is used to detect the dark current and charge with high resolution at these accelerators. At REGAE this resonator with electronics is installed to detect the bunch charge because charges below pC are used and this device can resolve it non-destructively. The same electronics as for the dark current and charge measurement is used and the resolution is measured to be 2.3 fC for 200 fC.  
poster icon Poster WEPF25 [0.822 MB]  
Production of Cavity BPMs for the European XFEL  
  • D. Lipka, D. Nölle, S. Vilcins
    DESY, Hamburg, Germany
  The DESY colleagues gave a comprehensive presentation of the large-scale cavity BPM system required for the XFEL (DESY), with most details are self-explaining by the slides. The XFEL cavity BPM pickup is based on a design from T. Shintake (Spring-8), a compact setup of waveguide loaded dipole mode and reference cavities, both utilizing a “magnetic”(loop) waveguide-to-coaxial transition for the signals. Both XFEL cavity BPM variants, for the beamline and the undulator, are made of stainless steel, to ensure a low-Q of ~70 (3.3GHz operating frequency), ensuring single bunch detection (bunch spacing 222ns). Details on the performance and manufacturing of the N-type feedthrough were given, which is based on a design of Shintake. Dirk went through the entire production process of the cavity BPMs, starting from the first prototypes until the full production series, which included some surprises. This contribution was very comprehensive, and most questions were answered by the presentation. On the cross coupling between the planes, Dirk mentioned better than 40dB!  
slides icon Slides FRWMJ5 [1.025 MB]