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Title LLRF Control of High Loaded-Q Cavities for the LCLS-II
  • C. Serrano, L.R. Doolittle, G. Huang, A. Ratti
    LBNL, Berkeley, California, USA
  • S. Babel, M. Boyes, B. Hong
    SLAC, Menlo Park, California, USA
  • R. Bachimanchi, C. Hovater
    JLab, Newport News, Virginia, USA
  • B.E. Chase, E. Cullerton, J. Einstein
    Fermilab, Batavia, Illinois, USA
Abstract The SLAC National Accelerator Laboratory is planning an upgrade (LCLS-II) to the Linear Coherent Light Source with a 4 GeV CW Superconducting Radio Frequency (SCRF) linac. The nature of the machine places stringent requirements in the Low-Level RF (LLRF) system, expected to control the cavity fields within 0.01 degrees in phase and 0.01% in amplitude, which is equivalent to a longitudinal motion of the cavity structure in the nanometer range. This stability has been achieved in the past but never for hundreds of superconducting cavities in Continuous-Wave (CW) operation. The difficulty resides in providing the ability to reject disturbances from the cryomodule, which is incompletely known as it depends on the cryomodule structure itself (currently under development at JLab and Fermilab) and the harsh accelerator environment. Previous experience in the field and an extrapolation to the cavity design parameters (relatively high Q_{L}c≈ 4×10⁷ , implying a half-bandwidth of around 16 Hz) suggest the use of strong RF feedback to reject the projected noise disturbances, which in turn demands careful engineering of the entire system.
Funding This work was supported by the LCLS-II Project and the U.S. Department of Energy, Contract DE-AC02-76SF00515
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Conference IPAC2016, Busan, Korea
Series International Particle Accelerator Conference (7th)
Proceedings Link to full IPAC2016 Proccedings
Session Poster Session
Date 11-May-16   16:00–18:00
Main Classification 06 Beam Instrumentation, Controls, Feedback and Operational Aspects
Sub Classification T27 Low Level RF
Keywords cavity, LLRF, controls, feedback, linac
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