Author: Bett, D.R.
Paper Title Page
WEPOR005 Ground Motion Compensation using Feed-forward Control at ATF2 2670
 
  • D.R. Bett, C. Charrondière, M. Patecki, J. Pfingstner, D. Schulte, R. Tomás
    CERN, Geneva, Switzerland
  • A. Jeremie
    IN2P3-LAPP, Annecy-le-Vieux, France
  • K. Kubo, S. Kuroda, T. Naito, T. Okugi, T. Tauchi, N. Terunuma
    KEK, Ibaraki, Japan
 
  Ground motion compensation using feed-forward control is a novel technique being developed to combat beam imperfections resulting from the vibration-induced misalignment of beamline components. The method is being evaluated experimentally at the KEK Accelerator Test Facility 2 (ATF2). It has already been demonstrated that the beam position correlates with the readings from a set of seismometers located along the beamline. To compensate for this contribution to the beam jitter, the fully operational system will use realtime measurement and processing in order to calculate and apply the feed-forward correction on a useful time scale. The progress towards a working system is presented in this paper.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR005  
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THPMB043 Progress in Ultra-Low β* Study at ATF2 3335
 
  • M. Patecki, D.R. Bett, F. Plassard, R. Tomás
    CERN, Geneva, Switzerland
  • K. Kubo, S. Kuroda, T. Naito, T. Okugi, T. Tauchi, N. Terunuma
    KEK, Ibaraki, Japan
  • M. Patecki
    Warsaw University of Technology, Warsaw, Poland
  • T. Tauchi, N. Terunuma
    Sokendai, Ibaraki, Japan
 
  A nanometer beam size in the interaction point (IP) is required in case of future linear colliders for achieving the desired rate of particle collisions. KEK Accelerator Test Facility (ATF2), a scaled down implementation of the beam delivery system (BDS), serves for investigating the limits of electron beam focusing at the interaction point. The goal of the ultra-low beta∗ study is to lower the IP vertical beam size by lowering the betay∗ value while keeping the betax∗ value unchanged. Good control over the beam optics is therefore required. The first experience with low beta∗ optics revealed a mismatch between the optics designed in the model with respect to the beam parameters observed in the experiment. Additionally, existing methods of beam parameters characterization at the IP were biased with high uncertainties making it difficult to set the desired optics. In this paper we report on the new method introduced in ATF2 for IP beam parameters characterization which gives a good control over the applied optics and makes the ultra-low beta∗ study possible to conduct. It can be also used for verifying the performance of some of the existing beam instrumentation devices.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB043  
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THPOR034 Bunch-by-bunch Position and Angle Stabilisation at ATF based on Sub-micron Resolution Stripline Beam Position Monitors 3859
 
  • N. Blaskovic Kraljevic, R.M. Bodenstein, T. Bromwich, P. Burrows, G.B. Christian, M.R. Davis, C. Perry, R.L. Ramjiawan
    JAI, Oxford, United Kingdom
  • D.R. Bett
    CERN, Geneva, Switzerland
 
  A low-latency, sub-micron resolution stripline beam position monitoring (BPM) system has been developed and tested with beam at the KEK Accelerator Test Facility (ATF2), where it has been used to drive a beam stabilisation system. The fast analogue front-end signal processor is based on a single-stage radio-frequency down-mixer, with a measured latency of 16 ns and a demonstrated single-pass beam position resolution of below 300 nm using a beam with a bunch charge of approximately 1 nC. The BPM position data are digitised on a digital feedback board which is used to drive a pair of kickers local to the BPMs and nominally orthogonal in phase in closed-loop feedback mode, thus achieving both beam position and angle stabilisation. We report the reduction in jitter as measured at a witness stripline BPM located 30 metres downstream of the feedback system and its propagation to the ATF interaction point.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR034  
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THPOR035 Development of a Low-latency, Micrometre-level Precision, Intra-train Beam Feedback System based on Cavity Beam Position Monitors 3862
 
  • N. Blaskovic Kraljevic, R.M. Bodenstein, T. Bromwich, P. Burrows, G.B. Christian, M.R. Davis, C. Perry, R.L. Ramjiawan
    JAI, Oxford, United Kingdom
  • D.R. Bett
    CERN, Geneva, Switzerland
 
  A low-latency, intra-train, beam feedback system utilising a cavity beam position monitor (BPM) has been developed and tested at the final focus of the Accelerator Test Facility (ATF2) at KEK. A low-Q cavity BPM was utilised with custom signal processing electronics, designed for low latency and optimal position resolution, to provide an input beam position signal to the feedback system. A custom stripline kicker and power amplifier, and a digital feedback board, were used to provide beam correction and feedback control, respectively. The system was deployed in single-pass, multi-bunch mode with the aim of demonstrating intra-train beam stabilisation on electron bunches of charge ~1 nC separated in time by c. 220 ns. The system has been used to demonstrate beam stabilisation to below the 75 nm level. Results of the latest beam tests, aimed at even higher performance, will be presented.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR035  
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