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Title Measurement of Beam Phase at FLASH using HOMs in Accelerating Cavities
  • L. Shi, R.M. Jones
    UMAN, Manchester, United Kingdom
  • N. Baboi, L. Shi
    DESY, Hamburg, Germany
  • N.Y. Joshipresenter
    University of Manchester, Manchester, United Kingdom
Abstract The beam phase relative to the accelerating field is of vital importance for the quality of photon beams produced in modern Free Electron Lasers based on superconducting (SC) cavities. Normally, the phase is determined by detecting the transient field induced by the beam. In this way the phase of each cavity is checked and adjusted typically every few months. In this paper, we present another means of beam phase determination, based on higher order modes (HOMs) excited in the 2nd monopole band by the beam inside the SC cavities. A circuit model of this HOM band is also presented. Various effects on the resolution have been studied. Circuit model simulations indicate the resolution is strongly dependent on the signal to noise ratio. Preliminary experimental results, based on a broadband setup, reveal an approximately 0.1o RMS resolution. These are in good agreement with simulation results. The work will pave the way for a dedicated system of beam phase monitoring, which is under development for the European XFEL. This will be the first implementation of a dedicated beam phase monitor, based on beam-excited HOMs in accelerating cavities.
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Conference IPAC2016, Busan, Korea
Series International Particle Accelerator Conference (7th)
Proceedings Link to full IPAC2016 Proccedings
Session Poster Session
Date 09-May-16   16:00–18:00
Main Classification 06 Beam Instrumentation, Controls, Feedback and Operational Aspects
Sub Classification T03 Beam Diagnostics and Instrumentation
Keywords HOM, cavity, electron, simulation, coupling
Publisher JACoW, Geneva, Switzerland
Editors Christine Petit-Jean-Genaz (CERN, Geneva, Switzerland); Dong Eon Kim (PAL, Pohang, Republic of Korea); Kyung Sook Kim (PAL, Pohang, Republic of Korea); In Soo Ko (POSTECH, Pohang, Republic of Korea); Volker RW Schaa (GSI, Darmstadt, Germany)
ISBN 978-3-95450-147-2
Published June 2016
Copyright © 2016 by JACoW, Geneva, Switzerland     CC-BY Creative Commons License
cc Creative Commons Attribution 3.0