Keyword: feedback
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MOAO03 Overview on the Diagnostics for EBS-ESRF storage-ring, SRF, radiation, diagnostics 9
 
  • L. Torino, N. Benoist, F. Ewald, E. Plouviez, J. Poitou, B. Roche, K.B. Scheidt, F. Taoutaou, F. Uberto
    ESRF, Grenoble, France
 
  On December 2018 the ESRF was shut down and the 28 years old storage ring was entirely dismantled in the following months. A new storage ring, the Extremely Brilliant Source (EBS), that had been pre-assembled in 2017 and 2018, is presently being installed and the commissioning will start in December 2019. EBS will achieve a much reduced horizontal emittance, from 4 nm to 150 pm, and will also provide the X-ray users with a more coherent synchrotron radiation beam. In this paper, we present an overview of the diagnostics systems for this new storage ring.  
slides icon Slides MOAO03 [40.660 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-MOAO03  
About • paper received ※ 03 September 2019       paper accepted ※ 07 September 2019       issue date ※ 10 November 2019  
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MOPP026 A Longitudinal Kicker Cavity for the BESSY II Booster cavity, kicker, booster, injection 149
 
  • T. Atkinson, M. Dirsat, A.N. Matveenko, A. Schälicke, B. Schriefer, Y. Tamashevich
    HZB, Berlin, Germany
  • T. Flisgen
    FBH, Berlin, Germany
 
  As part of the global refurbishment of the injector systems at BESSY II, a new longitudinal kicker cavity and suitable feedback will be installed in the booster. Both a flexible bunch charge and spacing is essential for efficient injection. Such a cavity is needed to mitigate the unwanted couple bunch instabilities associated with these elaborate filling patterns and the HOMs of additional accelerating structures. This paper covers the conceptual design, simulation strategy, manufacture and bench tests of the longitudinal kicker cavity before it is installed in the ring.  
poster icon Poster MOPP026 [4.756 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-MOPP026  
About • paper received ※ 02 September 2019       paper accepted ※ 07 September 2019       issue date ※ 10 November 2019  
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MOPP027 First Beam-based Test of Fast Closed Orbit Feedback System at GSI SIS18 controls, closed-orbit, synchrotron, acceleration 153
 
  • R. Singh, A. Doring, P. Forck, K. Lang, S.H. Mirza, D. Rodomonti, D. Schupp, M. Schwickert, H. Welker
    GSI, Darmstadt, Germany
  • A. Bardorfer
    I-Tech, Solkan, Slovenia
 
  Funding: European Unions Horizon 2020 Research and Innovation programme under Grant Agreement No. 730871 (ARIES). German Academic Exchange Service under Personal Reference No. 91605207.
The SIS18 synchrotron of GSI will be used as a booster ring for the SIS100 synchrotron built in the scope of the FAIR project. In order to preserve the beam quality during the whole acceleration ramp, a new closed orbit feedback (COFB) system is implemented at the SIS18 which operates with the existing BPMs and steerer magnets. The system aims for a bandwidth of several 100 Hz and robustness against the variation of the response matrix and the beam rigidity during the ramp. The architecture of the system and the results of the first beam-based test of the COFB hardware are presented. As a first step, the orbit correction is performed over the entire ramp using the response matrix corresponding to injection energy only taking the beam rigidity into account. Experimental observations of the bandwidth limitations arising from the temporal delay of the steerer power supplies and the spatial model variation during the ramp are compared with simulations. It is found that the temporal and the spatial model mismatch have similar effect on the achievable bandwidth of the COFB.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-MOPP027  
About • paper received ※ 07 September 2019       paper accepted ※ 08 September 2019       issue date ※ 10 November 2019  
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MOPP028 Longitudinal Bunch-by-Bunch Feedback Systems for SuperKEKB LER kicker, operation, timing, damping 158
 
  • M. Tobiyama, J.W. Flanagan, T. Kobayashi, S. Terui
    KEK, Ibaraki, Japan
  • J.D. Fox
    Stanford University, Stanford, California, USA
 
  Longitudinal bunch-by-bunch feedback systems to suppress coupled bunch instabilities with minimum bunch spacing of 2 ns have been constructed in SuperKEKB LER. Through the grow-damp and excite-damp experiments with several filling patterns and the transient-domain analysis of unstable modes, the behaviors of possible impedance sources have been evaluated. The measured performance of the system, together with the performance of the related systems such as slow phase feedback to the reference RF clock are reported.  
poster icon Poster MOPP028 [0.519 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-MOPP028  
About • paper received ※ 03 September 2019       paper accepted ※ 08 September 2019       issue date ※ 10 November 2019  
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MOPP030 Preliminary Test of XBPM Local Feedback in TPS electron, photon, operation, synchrotron 162
 
  • P.C. Chiu, J.-Y. Chuang, K.T. Hsu, K.H. Hu, C.H. Huang
    NSRRC, Hsinchu, Taiwan
 
  TPS is 3-GeV synchrotron light source which have opened for public users since September 2016 and now offers 400 mA top-up mode operation. The requirements of the long term orbit stability have been gradually more and more stringent. The report investigates the long-term orbit stability improved by applying local XBPM feedback.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-MOPP030  
About • paper received ※ 02 September 2019       paper accepted ※ 09 September 2019       issue date ※ 10 November 2019  
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MOPP031 Optimisation of the ISIS Proton Synchrotron Experimental Damping System damping, kicker, synchrotron, betatron 166
 
  • A. Pertica, D.W. Posthuma de Boer, R.E. Williamson
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  • J. Komppula
    CERN, Meyrin, Switzerland
 
  The ISIS Neutron and Muon Source, located in the UK, consists of a H linear accelerator, a rapid cycling proton synchrotron and two extraction lines delivering protons onto heavy metal targets. One of the limiting factors for achieving higher intensities in the accelerator is the head-tail instability present in the synchrotron, around 2ms after injection. In order to mitigate this instability, an experimental damping system is being developed for the ISIS synchrotron. Initial tests using a split electrode BPM as a pickup and a ferrite loaded kicker as a damper showed positive results. This paper describes the different developments made to the damping system and planned improvements to optimize its performance for use in normal operations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-MOPP031  
About • paper received ※ 04 September 2019       paper accepted ※ 09 September 2019       issue date ※ 10 November 2019  
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MOPP032 Fast Feedback Using Electron Beam Steering to Maintain the X-Ray Beam Position at a Monochromatic X-Ray Diagnostic at Diamond Light Source electron, synchrotron, power-supply, controls 171
 
  • C. Bloomer, G. Rehm, A. Tipper
    DLS, Oxfordshire, United Kingdom
 
  A new feedback system is being developed at Diamond Light Source, applying a modulation to the position of the electron beam to keep the synchrotron X-ray beam fixed at the sample-point. Beamline detectors operating in the 100-1000Hz regime are becoming common, and the X-ray beam stability demanded by beamlines is thus of comparable bandwidths. In this paper we present a feedback system operating at these bandwidths, using a diagnostic instrument permanently installed in the X-ray beam path to measure the error in beam position at the sample point, and fast air-cored magnets to apply a small modulation to the electron beam to compensate. Four magnets are used to generate electron beam bumps through an ID straight. This modulation of the beam away from the nominal orbit is small, less than 10 microns, but should be sufficient to compensate for the bulk of the X-ray motion observed at the sample. It is small enough that the impact on the machine will be negligible. This system aims to maintain X-ray beam stability to within 3% of a beam size, at bandwidths of up to 500Hz.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-MOPP032  
About • paper received ※ 09 September 2019       paper accepted ※ 10 September 2019       issue date ※ 10 November 2019  
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TUPP033 Laboratory and Beam Based Studies for Assessing the Performance of the New Fast Wire Scanners for the CERN Injector Complex controls, laser, operation, emittance 387
 
  • J. Emery, P. Andersson, W. Andreazza, J.M. Fernandez Ochoa, A. Goldblatt, D. Gudkov, F. Roncarolo, J.L. Sirvent, J. Tassan-Viol, R. Veness
    CERN, Geneva, Switzerland
 
  At CERN, fast beam wire scanners serve as reference transverse profile monitors in all synchrotrons. As part of the LHC Injector Upgrade project, a new generation of scanners has been designed to improve system reliability, precision and accuracy in view of higher brightness beams. This paper will discuss the performance achieved during both laboratory calibration and prototype testing with beam. The beam measurements performed in 2018 demonstrated excellent system reliability and reproducibility, while calibration in the laboratory showed that an accuracy below 10 um can be achieved on the wire position determination.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-TUPP033  
About • paper received ※ 04 September 2019       paper accepted ※ 08 September 2019       issue date ※ 10 November 2019  
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WECO02 Towards an Adaptive Orbit-Response-Matrix Model for Twiss-Parameter Diagnostics and Orbit Correction at Delta betatron, storage-ring, electron, software 477
 
  • S. Koetter, T. Weis
    DELTA, Dortmund, Germany
 
  At DELTA, a 1.5-GeV electron storage ring operated by the TU Dortmund University, preliminary tests of an adaptive orbit-response-matrix model were conducted. Closed orbit perturbations corrected by the slow orbit feedback can be buffered and used to update a fit of the bilinear-exponential model with dispersion (BE+d model). This model is a representation of the orbit-response matrix depending on the beta functions, the betatron phases and the tunes in both planes. This work introduces a new fitting recipe to obtain good estimates of the aforementioned quantities and evaluates a BE+d-model represented orbit-response matrix for orbit correction. Numerical studies are shown along with measurement results.  
slides icon Slides WECO02 [0.657 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WECO02  
About • paper received ※ 04 September 2019       paper accepted ※ 08 September 2019       issue date ※ 10 November 2019  
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WECO03 Tune Computation via Model Fitting to Swept Machine Response Measurement synchrotron, operation, betatron, resonance 482
 
  • M.G. Abbott, G. Rehm
    DLS, Oxfordshire, United Kingdom
 
  At Diamond Light Source we compute the horizontal and vertical tunes by fitting a simple multi-pole resonator model to the measured electron beam frequency response. The transverse (and longitudinal) tune response is measured by sweeping an excitation across the range of possible tune frequencies and synchronously measuring the IQ response. The multi-pole resonator model is a good fit to the measured behaviour, but the fitting process is surprisingly challenging. Problems include noisy measurements, very complex beam responses in the presence of increasing chromaticity, poor data when the beam is close to instability, and a number of challenges with the stability of the algorithm. The tune fitting algorithm now in use at Diamond has been developed and refined over many years. It is finally stable enough to work reliably throughout most beam operating conditions. The algorithm involves alternating peak finding and non-linear fitting, with a fairly naive mathematical approach; the main focus is on providing reliable results.  
slides icon Slides WECO03 [1.059 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WECO03  
About • paper received ※ 04 September 2019       paper accepted ※ 09 September 2019       issue date ※ 10 November 2019  
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THAO02 Towards Full Silicon 4H-SiC Based X-Ray Beam Monitoring synchrotron, storage-ring, monitoring, experiment 663
 
  • M. Camarda, M. Birri, M. Carulla, D. Grolimund, B. Meyer, C. Pradervand
    PSI, Villigen PSI, Switzerland
  • U. Grossner, S.M. Nida, A. Tsibizov, T. Ziemann
    ETH, Zurich, Switzerland
 
  In this work, we present extensive theoretical and experimental results of novel Silicon Carbide x-ray sensors for beam position monitoring (XBPM). Until recently, diamond, was considered the material-of-choice for continuous monitoring of hard (>6keV) x-ray beams at synchrotron light sources. Diamond XBPM are now commercially available as single crystal* and polycrystalline** sensors. However, in a recently published paper***, we have shown that Silicon Carbide is superior to both diamond crystal types in several critical aspects. Specifically, we found superior electrical characteristics (sensor dynamics, signal uniformity, signal strength) and superior optical properties (full device transparency, device active area, signal strength) when compared to commercial polycrystalline and single crystal diamond, respectively. We also succeeded in the ’industrialization’ of the SiC fabrication process, allowing for the simultaneous realization of several (>40) sensors in up to 4’ SiC wafers, with high yields. More recently we have also analyzed the fluorescence of SiC sensors as compared to YAG ones, finding that SiC can also be used for hybrid position/shape monitoring schema.
* CIVIDEC. AT, SYDORTECHNOLOGIES. COM
** DECTRIS. COM
*** S. Nida, et. al. Silicon carbide X-ray beam position monitors for synchrotron applications J. Synchrotron Rad. 26, 28-35 (2019)
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-THAO02  
About • paper received ※ 11 September 2019       paper accepted ※ 11 September 2019       issue date ※ 10 November 2019  
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