Author: Fong, K.
Paper Title Page
MOP036 Microphonics Suppression Study in ARIEL e-Linac Cryomodules 136
 
  • Y. Ma, K. Fong, J.J. Keir, D. Kishi, S.R. Koscielniak, D. Lang, R.E. Laxdal, S. Liu, R.S. Sekhon, X. Wang
    TRIUMF, Vancouver, Canada
 
  Now the stage of the 30 MeV portion of ARIEL (The Advanced Rare Isotope Laboratory) e-Linac (1.3 GHz, SRF) is under commissioning which includes an injector cryomodule (ICM) with a single nine-cell cavity and the 1st accelerator cryomodule (ACM1) with two cavities configuration. The two ACM1 cavities are driven by a single klystron with vector-sum control and running in CW mode. We have observed a ponderomotive instability in ACM1 driven by the Lorentz force and seeded through microphonics that impacts beam stability [1-5]. Extensive damping has been implemented during a recent shut-down. The beam test results show 20 MeV acceleration gain can be reached by ACM1. A fast piezoelectric (Pie-zo) tuner is under development to allow a fast tuning compensation for the e-Linac cavities. In this paper, the progress of the microphonics suppression of Cryomod-ules is presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP036  
About • paper received ※ 24 June 2019       paper accepted ※ 01 July 2019       issue date ※ 14 August 2019  
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THP074 Microphonics Noise Suppression with Observer Based Feedback 1068
SUSP004   use link to see paper's listing under its alternate paper code  
 
  • M. Keikha, K. Fong
    TRIUMF, Vancouver, Canada
  • M. Moallem
    SFU, Surrey, Canada
 
  Funding: TRIUMF
Detuning of superconducting radio frequency (SRF) cavities is mainly caused by the Lorentz force, which is the radiation pressure induced by a high radio frequency (RF) field, and environmental mechanical vibrations that induce undesirable interference signals referred to as microphonics. Both of these influences can be described by a second order differential equation of the mechanical vibration modes of the cavity. In this paper we consider three dominant mechanical modes of the system and develop a control scheme based on input-output linearization. It is shown through simulation studies that the proposed control technique can successfully the suppress microphonic noise due to the SRF cavity’s dynamics.
 
poster icon Poster THP074 [0.610 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP074  
About • paper received ※ 22 June 2019       paper accepted ※ 01 July 2019       issue date ※ 14 August 2019  
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THP076 Simulation Analysis of Lorentz Force Induced Oscillations in RF Cavities in Vector Sum and Cw Operation 1078
 
  • R. Leewe, K. Fong
    TRIUMF, Vancouver, Canada
 
  Within TRIUMFs electron LINAC, two TESLA type cavities are operated with a single klystron in CW mode. Vector sum control is applied for field stabilization and the resonance frequencies are individually tuned with a proportional feedback controller. First operational experiences showed that amplitude oscillations can start in both cavities, while the vector sum is perfectly stable. These instabilities occur at high operating fields and are driven by Lorentz force changes. This paper presents a simulation study of multiple cavities in vector sum operation with respect to Lorentz force oscillations. It will be shown that all cavities in operation have to be damped to guarantee system stability.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP076  
About • paper received ※ 22 June 2019       paper accepted ※ 02 July 2019       issue date ※ 14 August 2019  
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