Author: Diaz Cruz, J.A.
Paper Title Page
THPOPA21 Narrow Bandwidth Active Noise Control for Microphonics Rejection in Superconducting Cavities at LCLS-II 785
SUPCPA06   use link to see paper's listing under its alternate paper code  
  • A. Bellandi, J. Branlard
    DESY, Hamburg, Germany
  • S. Aderhold, A.L. Benwell, A. Brachmann, J.A. Diaz Cruz, D. Gonnella, S.L. Hoobler, J. Nelson, A. Ratti, L.M. Zacarias
    SLAC, Menlo Park, California, USA
  • J.A. Diaz Cruz
    UNM-ECE, Albuquerque, USA
  • R.D. Porter
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  LCLS-II is an X-Ray Free Electron Laser (XFEL) under commissioning at SLAC, being the first Continuous Wave (CW) hard XFEL in the world to come into operation. To accelerate the electron beam to an energy of 4 GeV, 280 superconducting cavities of the TESLA types are used. A Loaded Q (QL) value of 4x107 is used to drive the cavities at a power level of a few kilowatts. For this QL value, the RF cavity bandwidth is equal to 32 Hz. Therefore, keeping the cavity resonance frequency within such bandwidth is imperative to avoid a significant increase in the required RF power. In superconducting accelerators, resonance frequency variations are produced by mechanical microphonic vibrations of the cavities. One source of microphonics noise is rotary machinery such as vacuum pumps or HVAC equipment. A possible method to reject these disturbances is to use Narrowband Active Noise Control (NANC) techniques. Such a technique was already tested at DESY/CMTB and Cornell/CBETA. This proceeding presents the implementation of a NANC controller in the LCLS-II Low Level RF (LLRF) control system. Tests on the rejection of LCLS-II microphonics disturbances are also presented.  
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About • Received ※ 24 August 2022 — Revised ※ 30 August 2022 — Accepted ※ 02 September 2022 — Issue date ※ 26 September 2022
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