Author: Fox, J.D.
Paper Title Page
TUZGBD4 Impact of a Wideband Feedback Prototype System on TMCI in the SPS 1208
 
  • W. Höfle, H. Bartosik, E.R. Bjørsvik, G. Kotzian, T.E. Levens, K.S.B. Li
    CERN, Geneva, Switzerland
  • J.E. Dusatko, J.D. Fox, C.H. Rivetta
    SLAC, Menlo Park, California, USA
  • O. Turgut
    Stanford University, Stanford, California, USA
 
  The transverse mode coupling instability (TMCI) in the SPS has been identified as one of the potential performance limitations for future high intensity LHC beams that will be required for the High Luminosity (HL)-LHC era and is being addressed by the LHC Injector Upgrade Project (LIU). A potential mitigation can be provided by wideband feedback systems with a frequency reach of about 1 GHz . For this reason, the development of a prototype system has been started in a CERN collaboration within the US-LARP framework in 2008. In this report we present latest experimental results in 2017 where this prototype system was used in single and multi-bunch studies. In particular, a successful mitigation against TMCI at injection could be demonstrated in single bunch studies.  
slides icon Slides TUZGBD4 [15.120 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUZGBD4  
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WEPAF073 Ultra-Wideband Transverse Intra-Bunch Feedback: Beginning Development of a Next Generation 8GSa/s System 2001
 
  • J.E. Dusatko, J.D. Fox
    SLAC, Menlo Park, California, USA
 
  Funding: US Department of Energy DE-AC02-76SF00515, US LHC Accelerator Research Program, CERN LHC Injector Upgrade Project and the US-Japan Cooperative Program in High Energy Physics.
Building on the success of our 4GSa/s wideband trans-verse feedback system, we have begun development of a next generation ultra-wideband feedback processor which doubles the effective sampling rate to 8GSa/s. This higher sampling rate and proportional increase in analog band-width enable enhanced flexibility and diagnostics for accelerator transverse feedback such as control of higher-order modes, more detailed diagnostic information, im-proved SNR and two channel processing of total charge and orbit signals, with multiple pickups. Though targeted for ongoing transverse intra-bunch instability studies at the CERN SPS with a 1.7ns bunch length, the increased performance paves the way for instability control and diagnostics applications for other machines such as the HL-LHC and FCC. This paper discusses the beginning development process including an evaluation of the high-est speed AtoD and DtoA data converter devices at time of this writing and selection of the devices used in our design. It then describes the architecture of the full 8GSa/s prototype feedback processor and the design approach, which involves using both custom and commercial components enabling rapid and flexible development.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF073  
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WEPAL079 Control of Intra-Bunch Vertical Motion in the SPS with GHz Bandwidth Feedback 2365
 
  • J.D. Fox, J.E. Dusatko, C.H. Rivetta, O. Turgut
    SLAC, Menlo Park, California, USA
  • H. Bartosik, E.R. Bjørsvik, W. Höfle, G. Kotzian, K.S.B. Li, E. Métral, B. Salvant, U. Wehrle
    CERN, Geneva, Switzerland
  • S. De Santis
    LBNL, Berkeley, California, USA
 
  Funding: Work supported by the U.S. Department of Energy DE-AC02-76SF00515, US LHC Accelerator Research program, CERN LHC Injector Upgrade Project and the US-Japan Cooperative Program in High Energy Physics.
A GHz bandwidth vertical beam feedback system has been in development at the CERN SPS to explore control of unstable beam motion in single bunch and bunch train configurations. We present measurements and recent studies of stable and unstable motion for intensities up to 2x1011 p/bunch. The system has been operated at 3.2GS/s with 16 samples across a 5 ns RF bucket (4.2 ns 3 σ bunch at injection). Experimental results confirm damping of intra-bunch instabilities in Q20, Q22 and Q26 optics configurations. Instabilities with growth times of 200 turns are well-controlled from injection, consistent with the achievable gains for the 2 installed stripline kickers with 1 kW broadband total power. Studies of the damping achieved with the diagonal FIR controllers and existing system noise floors are highlighted to evaluate benefits of MIMO feedback controllers. The work is motivated by anticipated intensity increases from the LIU and HL-LHC upgrade programs, and has included the development of a new 1 GHz bandwidth slotline kicker structure and associated amplifier system
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL079  
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