Oct 9 – 13, 2022
FHNW Campus Brugg-Windisch
Europe/Zurich timezone

Narrow Bandwidth Active Noise Control for microphonics rejection in superconducting cavities at LCLS-II

Oct 12, 2022, 3:13 PM
Lichthof (Building 1)


Building 1

Poster Low Level RF Workshop 2022 Poster Session


Andrea Bellandi (Deutsches Elektronen-Synchrotron)


LCLS-II is an X-Ray Free Electron Laser (XFEL) com-
missioned in 2022, being the first Continuous Wave (CW)
hard XFEL in the world to come into operation. To accel-
erate the electron beam to an energy of 4 GeV, 280 TESLA
type superconducting RF (SRF) cavities are used. A Loaded
Q (𝑄𝐿 ) of 4×10^7 is used to drive the cavities at a power level
of a few kilowatts. For this 𝑄𝐿 , the RF cavity bandwidth is
32 Hz. Therefore, keeping the cavity resonance frequency
within such bandwidth is imperative to avoid a significant
increase in the required drive 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 using the LCLS-II Low Level RF (LLRF) control
system. Tests on the rejection of LCLS-II microphonics
disturbances are also presented.

Primary authors

Andrea Bellandi (Deutsches Elektronen-Synchrotron) Mr Jorge Diaz Cruz (Stanford Linear Accelerator Center)


Dr Sonya Hoobler (Stanford Linear Accelerator Center) Dr Julien Branlard (Deutsches Elektronen-Synchrotron) Dr Alessandro Ratti (Stanford Linear Accelerator Center) Dr Sebastian Aderhold (Stanford Linear Accelerator Center) Dr Andy Benwell (Stanford Linear Accelerator Center) Dr Axel Brachman (Stanford Linear Accelerator Center) Dr Dan Gonnella (Stanford Linear Accelerator Center) Dr Janice Nelson (Stanford Linear Accelerator Center) Dr Ryan Douglas Porter (Stanford Linear Accelerator Center) Ms Lisa Zacarias (Stanford Linear Accelerator Center)

Presentation materials