TUCL —  BPMs and Beam Stability   (13-Sep-16   14:30—16:00)
Chair: S.R. Marques, LNLS, Campinas, Brazil
Paper Title Page
Wideband Stripline BPM for Precise Measurements of Internal Bunch Motion in Proton Synchrotrons  
  • T. Toyama
    KEK, Ibaraki, Japan
  • T. Toyama
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  The talk will review the recent progress of the tapered coupler in BPM striplines and its characteristics in terms of time and frequency responses and position sensitivity. Its application to the intra-bunch feedback will be mentioned.  
slides icon Slides TUCL01 [11.822 MB]  
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TUCL02 Novel Accelerator Physics Measurements Enabled by NSLS-II RF BPM Receivers 294
  • B. Podobedov, W.X. Cheng, Y. Hidaka
    BNL, Upton, Long Island, New York, USA
  • D. Teytelman
    Dimtel, San Jose, USA
  NSLS-II light source has state of the art RF BPM receivers that were designed and built in-house incorporating the latest technology available in the RF, digital, and software domains. The recently added capability to resolve the orbits of multiple bunches within a turn as well as further improvement in transverse positional resolution for single- and few-bunch fills [*] allowed us to perform a number of novel beam dynamics measurements. These include measuring small impedances of vacuum chamber components, and of extremely small (~10-5) current-dependent tune shifts (transverse and synchrotron), as well as obtaining an amplitude-dependent tune shift curve from a single kicker pulse. We are also effectively utilizing our BPMs to decipher the lifetimes of individual bunches and to visualize single bunch instability dynamics. In this paper we review the unique capabilities of NSLS-II BPMs and present examples of beam physics measurements that greatly benefit from them.
* B. Podobedov, W. Cheng, K. Ha, Y. Hidaka, J. Mead, O. Singh, K. Vetter "Single Micron Single-Bunch Turn-by-Turn BPM Resolution Achieved at NSLS-II", in Proc. IPAC'16, Busan, Korea, May 2016, WEOBB01
slides icon Slides TUCL02 [5.788 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUCL02  
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TUCL03 Measurements of Longitudinal Coupled Bunch Instabilities and Status of New Feedback System 298
  • G. Rehm, M.G. Abbott, A.F.D. Morgan
    DLS, Oxfordshire, United Kingdom
  We have modified the vertical bunch-by-bunch feedback to also provide a longitudinal kick on a separate input. Using our existing drive/damp system and a modulator/amplifier to the required 1.5 GHz we are thus able to characterise the damping rates of all coupled bunch instabilities, while not able to provide feedback. At the same time, we have started the development of a completely new longitudinal feedback system based on commercially available components, providing 500MS/s, 14 bit conversion in and out, powerful Virtex 7 field programmable gate array for digital signal processing and 32GB of on board buffer for recording data. We report on the status of the development and our plans to bring the new system into use.  
slides icon Slides TUCL03 [2.897 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUCL03  
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