Keyword: feedback
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MOOCB02 A Common Operation Metrics for Third Generation Light Sources operation, experiment, survey, insertion 56
 
  • A. Lüdeke
    PSI, Villigen PSI, Switzerland
  • M. Bieler
    DESY, Hamburg, Germany
  • J.-F. Lamarre
    SOLEIL, Gif-sur-Yvette, France
  • M. Pont
    CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
  
  High reliability is a very important goal for third generation light sources. Very often the beam availability is used as the operation metrics to measure the reliability of the accelerator. A survey at several light sources revealed that the calculation of this statistics varies significantly between facilities. This prevents a useful comparison of their reliabilities. The authors propose a specific metrics for the reliability of third generation light sources; a metrics that will allow a detailed and meaningful comparison of these particle accelerators.  
slides icon Slides MOOCB02 [0.701 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOOCB02  
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MOPRO081 Resonance Frequency Feedback System for a Precise Magnet Alignment using Multi-vibrating Wires resonance, quadrupole, alignment, emittance 277
 
  • K. Fukami, N. Azumi, T. Fujita, T. Honiden, H. Kimura, T. Nakanishi, Y. Okayasu, C. Zhang
    JASRI/SPring-8, Hyogo-ken, Japan
  • K. Kajimoto, T. Watanabe
    SES, Hyogo-pref., Japan
  • S. Matsui
    RIKEN/SPring-8, Hyogo, Japan
  
  An ultimate storage ring (USR) is being designed at synchrotron radiation facilities in the world. USR can generate theoretically minimum synchrotron radiation because emittance of the USR is less than diffraction limit of the radiation. The USR requires high alignment precision of micro-meter order. A vibrating wire method (VWM) has widely been used for such a high precision alignment. An error field of multi-pole magnet is estimated by detecting a vibration of a single wire excited with AC current. The wire position, where no vibration is excited, is defined as the magnetic center. The applied frequency is kept on a resonant frequency, which may drift due to temperature change etc. during the measurement. To trace the resonant frequency at all times, we developed a frequency feedback system. It is necessary to trace the resonance, even when the wire is set in the vicinity of the magnetic center where the magnetic field is nearly zero. Here we propose to install one or two additional wires parallel to the original wire. The additional wires off the center can detect the vibration frequency with enough S/N ratio. We discuss the effectiveness of it for quick and reliable alignment.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO081  
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MOPME050 Reliable Software Development for Machine Protection Systems software, controls, framework, interface 489
 
  • J.C. Garnier, D. Anderson, M. Audrain, M. Dragu, K. Fuchsberger, A.A. Gorzawski, M. Koza, K.H. Krol, K. Misiowiec, K. Stamos, M. Zerlauth
    CERN, Geneva, Switzerland
  
  The Controls software for the Large Hadron Collider (LHC) at CERN, with more than 150 millions lines of code, resides amongst the largest known code bases in the world. Industry has been applying agile software engineering techniques for decades now, and the advantages of these techniques can no longer be ignored to manage the code base for large projects within the accelerator community. Furthermore, CERN is a particular environment due to the high personnel turnover and manpower limitations, where applying agile processes can improve both, the codebase management as well as its quality. This paper presents the successful application of the agile software development process SCRUM for machine protection systems at CERN, the quality standards and infrastructure introduced together with the agile process as well as the challenges encountered to adapt it to CERN’s environment.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPME050  
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MOPME058 The Magnet Power Supply for PAL-XFEL controls, power-supply, FPGA, embedded 504
 
  • K.-H. Park, Y.-G. Jung, D.E. Kim, I.S. Ko, H.-G. Lee, S.B. Lee, H.S. Suh
    PAL, Pohang, Kyungbuk, Republic of Korea
  • W.S. Choi, M.J. Kim
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  
  A magnet power supply (MPS) for PAL-XFEL was developed, which is the bipolar type with the power capacity of 3.6KW. The MPS has been implemented by the digital signal processing technology using the DSP, FPGA, ADCs and so on. An embedded module was adapted for the Ethernet connection for EPCIS. The output current stability of the MPS showed about 10 ppm peak-to-peak in long term experiment. The measured accuracy was less than 10ppm in full range. The other experimental results such as repeatability and zero-cross response were given in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPME058  
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MOPME061 Design of a Three Legs and Phase Shift AC to DC Converter for Taiwan Photon Light Source controls, operation, power-supply, electronics 511
 
  • Y.S. Wong, K.-B. Liu
    NSRRC, Hsinchu, Taiwan
  • J.F. Chen, W.C. Hsu, W.C. Hung, P.H. Tseng
    NCKU, Tainan city, Taiwan
  
  A novel low voltage high current AC/DC converter will be achieved which input is utility power supplies a low voltage DC output to load. The new three legs phase shift AC / DC power supply, can divided to five parts : diode full bridge rectifier, three legs phase shift control circuits, transformers, double inductor circuit and feedback circuit. Circuit operates as a single-phase 110 Vrms AC mains power input three legs phase shift control mode from the diode bridge rectifier circuit, the output voltage through the transformer and the phase shift control method converts to low voltage DC 12V output and supplies to loading, feedback circuit are using a feedback resistor across the filter capacitor voltage to product a feedback signal. Digital signal processing (DSP) control board by a feedback voltage determines the three legs phase shift displacement in order to control the output voltage keep a constant value 12V. For this circuit have a zero voltage switching characteristics of the three legs phase shift mode power supply, the input voltage for single phase 110Vac and output load power is 12V/20A.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPME061  
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MOPME062 The Acceptance Measurement Platform for TPS Corrector Magnet Power Supplies data-acquisition, interface, power-supply, controls 514
 
  • B.S. Wang, Y.-C. Chien, C.-Y. Liu, K.-B. Liu, Y.S. Wong
    NSRRC, Hsinchu, Taiwan
  
  This paper presents an implementation of a multi-channel measuring data acquisition interface of corrector magnet power supplies (CMPS) for Taiwan Photon source (TPS) with LabVIEW as the developing tool. The multi-channel measuring data acquisition interface could reduce quantity of measurement instrument and loading of operator at the CMPS acceptance test. The instrument devices of measurement system include a multiplexer 、a dynamic signal analyzer (DSA) and a high-resolution digital voltage meter (DVM), GPIB is the communication interface between the multi-channel measuring data acquisition interface and instruments. There are two analyzing procedure for the output current of MPS in the default setting of the LabVIEW program, 1) Fast Fourier Transform of output current measured by DSA, 2) long-term stability of output current measured by DVM; after these two analyzing procedure is completed, the performance of each MPS can be automatically generated as a Microsoft Word report file.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPME062  
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MOPME069 Upgrade of the Injection Kicker System for J-PARC Main Ring injection, kicker, timing, operation 526
 
  • T. Sugimoto, K. Fan, K. Ishii, H. Matsumoto
    KEK, Ibaraki, Japan
  
  Four lumped inductance injection kicker magnets for the J-PARC main ring (MR) produce a kick of 0.1096 T·m with a 1% to 99% rise-time of about 400 nsec. A residual field of about 6% of the flat-top exists at the tail of the pulse due to an impedance mismatching. The residual field is required to be suppressed less than 1% to reduce injection losses. For a higher intensity beam operation, the kicker rise-time of less than 300nsec is required to inject longer beam bunches which reduces a space charge effect. During the long shutdown in FY2013, 140Ω resistor and 7nF capacitor were connected to the thyratron to improve the post-pulse shape. In addition, an optimization of a capacitance in the matching circuit was carried out to optimize the waveform. As the result, the rise-time of 195nsec and the residual tail field of 2% were achieved. However, another reflection peak of about 9% is appeared. We plan to compensate the effect of the new peak by using a new small kicker magnet. This paper discusses the detail of the circuit and the beam test results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPME069  
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MOPRI042 Recent Developments at the High-charge PHIN Photoinjector and the CERN Photoemission Laboratory laser, cathode, vacuum, operation 695
 
  • C. Heßler, E. Chevallay, S. Döbert, V. Fedosseev, I. Martini, M. Martyanov, A. Perillo Marcone, Sz. Sroka
    CERN, Geneva, Switzerland
  
  The high-charge PHIN photoinjector has originally been developed to study the feasibility of a photoinjector option for the drive beam of the CLIC Test Facility 3 (CTF3) at CERN and is now being used to investigate the feasibility of a drive beam photoinjector for CLIC. In this paper recent R&D efforts to improve the parameters of the existing system towards CLIC requirements will be discussed. This includes studies of a feedback loop for intensity stabilization, the upgrade of the PHIN vacuum system and the planned upgrade of the driving laser system. For photocathode production and R&D a dedicated photoemission laboratory is available at CERN. To increase the production rate of photocathodes and the availability of the photoemission lab for other studies, an upgrade of the photocathode preparation system with a load-lock system is under study and will also be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI042  
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TUPRO059 Beam Energy Measurements using Resonant Spin Depolarization at ALBA polarization, resonance, beam-losses, synchrotron 1168
 
  • Z. Martí, U. Iriso, F. Pérez
    CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
  
  Energy measurements with precision down to 10-5 are inferred from the lifetime evolution when the beam is depolarized using AC kicks with the Transverse Fast Feedback system. Lifetime measurements are carried out using the DCCT, the BPM sum signals, pin-diode BLMs, and a scintillator based Beam Loss Detector. Results obtained with this instrumentation are reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO059  
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TUPRO115 Progress on the Dipole Magnet for a Rapid Cycling Synchrotron dipole, simulation, synchrotron, magnet-design 1322
 
  • H. Witte, J.S. Berg
    BNL, Upton, Long Island, New York, USA
  • M.L. Lopes
    Fermilab, Batavia, Illinois, USA
  
  Funding: Work supported by Brookhaven Science Associates, LC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
A rapid cycling hybrid synchrotron has been proposed for the acceleration of muons from 375 to 750 GeV. The bending in a hybrid synchrotron is created with interleaved cold and warm dipoles; the warm dipoles modulate the average bending field for the different particle momenta. A key challenge for the warm dipole magnets is the ramp rate, which is equivalent to frequencies of 400-1000 Hz. Recently a design has been suggested which employs 6.5 Si steel for the return yoke and FeCo for the poles. In simulations the design has shown a good performance (up to 2T) due to the FeCo and acceptable power losses by employing SiFe with a high Si content. The paper discusses the effect of eddy currents induced in the laminations and hysteresis effects on the field quality. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO115  
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TUPME008 Status of the CLIC-UK R&D Programme on Design of Key Systems for the Compact Linear Collider cavity, collider, quadrupole, linear-collider 1354
 
  • P. Burrows, R. Ainsworth, T. Aumeyr, D.R. Bett, N. Blaskovic Kraljevic, L.M. Bobb, S.T. Boogert, A. Bosco, G.B. Christian, L. Corner, F.J. Cullinan, M.R. Davis, D. Gamba, P. Karataev, K.O. Kruchinin, A. Lyapin, L.J. Nevay, C. Perry, J. Roberts, J. Snuverink, J.R. Towler
    JAI, Oxford, United Kingdom
  • R. Ainsworth, T. Aumeyr, S.T. Boogert, A. Bosco, P. Karataev, K.O. Kruchinin, L.J. Nevay, J.R. Towler
    Royal Holloway, University of London, Surrey, United Kingdom
  • P.K. Ambattu, G. Burt, A.C. Dexter, M. Jenkins, S. Karimian, C. Lingwood, B.J. Woolley
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • L.M. Bobb, R. Corsini, D. Gamba, A. Grudiev, A. Latina, T. Lefèvre, C. Marrelli, M. Modena, J. Roberts, H. Schmickler, D. Schulte, P.K. Skowroński, J. Snuverink, S. Stapnes, F. Tecker, R. Tomás, R. Wegner, M. Wendt, W. Wuensch
    CERN, Geneva, Switzerland
  • J.A. Clarke, S.P. Jamison, P.A. McIntosh, B.J.A. Shepherd
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • N.A. Collomb, D.G. Stokes
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
  • L. Corner
    Oxford University, Physics Department, Oxford, Oxon, United Kingdom
  • W.A. Gillespie, R. Pan, M.A. Tyrk, D.A. Walsh
    University of Dundee, Nethergate, Dundee, Scotland, United Kingdom
  • R.M. Jones
    UMAN, Manchester, United Kingdom
  
  Six UK institutes are engaged in a collaborative R&D programme with CERN aimed at demonstrating key aspects of technology feasibility for the Compact Linear Collider (CLIC). We give an overview and status of the R&D being done on: 1) Drive-beam components: quadrupole magnets and the beam phase feed-forward prototype. 2) Beam instrumentation: stripline and cavity beam position monitors, an electro-optical longitudinal bunch profile monitor, and laserwire and diffraction and transition radiation monitors for transverse beam-size determination. 3) Beam delivery system and machine-detector interface design, including beam feedback/control systems and crab cavity design and control. 4) RF structure design. In each case, where applicable, we report on the status of prototype systems and performance tests with beam at the CTF3, ATF2 and CesrTA test facilities, including plans for future experiments.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME008  
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TUPME009 A Sub-micron Resolution, Wide-band, Stripline BPM System for Driving Bunch-by-bunch Feed-back and Feed-forward Systems at ATF kicker, cavity, operation, extraction 1358
 
  • G.B. Christian, D.R. Bett, N. Blaskovic Kraljevic, P. Burrows, M.R. Davis, Y.I. Kim, C. Perry
    JAI, Oxford, United Kingdom
  
  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 as part of a beam stabilisation system. The fast analogue front-end signal processor is based on a single-stage RF down-mixer and a position resolution below 400 nm has been demonstrated for beam intensities of ~1 nC, with single-pass beam. The BPM position data are digitised by fast ADCs on an FPGA-based digital feedback controller, which is used to drive either a pair of kickers local to the BPMs and nominally orthogonal in phase, in closed-loop feedback mode, or a downstream kicker in the ATF2 final focus region, in feedforward mode. The beam jitter is measured downstream of the final focus system with high resolution, low-Q, cavity BPMs, and the relative performance of both systems in stabilising the beam is compared.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME009  
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TUPRI016 First Studies on Ion Effects in the Accelerator ELSA ion, electron, synchrotron, quadrupole 1585
 
  • D. Sauerland, W. Hillert, M.T. Switka
    ELSA, Bonn, Germany
  • A. Markoviḱ, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • A. Meseck
    HZB, Berlin, Germany
  
  Funding: BMBF (Federal Ministry of Education and Research)
In the ELSA stretcher ring electrons are accelerated by a fast energy ramp of 6 GeV/s to a beam energy of 3.2 GeV. The high energetic electrons ionize the residual gas molecules in the beam pipe by collisions or synchrotron radiation. The generated ions in turn accumulate inside the beam potential, causing several undesired effects such as tune shifts and beam instabilities. These effects are studied experimentally at ELSA using its full diagnostic capabilities. Both tune shifts due to beam neutralization and transversal beam-ion instabilities can be determined from the beam spectrum. Additionally the beam's transfer function can be measured using a broadband transversal kicker. In the stretcher ring at a beam energy of 1.2 GeV, a periodic beam blow-up was detected in the horizontal plane. Additional measurements of the transversal beam spectrum and ns-time resolution observations with a streak camera identified this blow-up as a coherent dipole oscillation of the beam. This horizontal instability is presumably caused by trapped ions, as there is a strong correlation with the high voltage-bias of the clearing electrodes. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI016  
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TUPRI018 Transition Energy Crossing in the Future FAIR SIS-100 for Proton Operation space-charge, proton, quadrupole, synchrotron 1591
 
  • S. Aumon, D. Ondreka, S. Sorge
    GSI, Darmstadt, Germany
  • K. Groß
    TEMF, TU Darmstadt, Darmstadt, Germany
  
  The FAIR project foresees to deliver an intense single bunch beam with 2·1013 protons of 50ns duration to the experiments. Besides the original γt-shift scenario, an alternative RF proton cycle has been recently studied: the transition energy is crossed with possibly a gamma transition jump. The flexibility of the lattice allowing to change the value of γt, a transition crossing has been considered for two possible energies. This challenging scenario is limited by several constraints such as space charge, a small momentum acceptance and by the required RF manipulations aiming to produce the final single bunch beam in the future SIS-100. This paper focuses on how the high intensity beam would suffer of the mismatch in bunch length at transition and new sets of beam parameter are defined for the proton beam. The jump quadrupole system is also presented. The applicability of the foreseen longitudinal feedback system to cure quadrupolar oscillations is also discussed in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI018  
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TUPRI036 Fast Ion Instability at CESR-TA vacuum, ion, simulation, electron 1638
 
  • A. Chatterjee, K.J. Blaser, M. P. Ehrlichman, D. L. Rubin, J.P. Shanks
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Funding: Work supported by NSF and DOE Contracts No. PHY-0734867, No. PHY-1002467, No. PHYS-1068662, No. DE-FC02-08ER41538, No. DE-SC0006505, and the Japan/U.S. Cooperation Program.
Fast Ion Instability can lead to deterioration of an electron beam (increasing emittance and instability of a train of bunches) in storage rings and linacs. We study this at the Cornell Electron Storage Ring Test Accelerator using a 2.1 GeV low emittance beam. As the source of ions is residual gas, our measurements are conducted at various pressures, including nominal vacuum as well as injected gas (Ar, Kr). We measure turn-by-turn vertical bunch size and position, as well as the multi-bunch power spectrum. A detailed simulation is then used to compare theory with observations. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI036  
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TUPRI041 Study of Collective Beam Instabilities for Sirius impedance, vacuum, undulator, operation 1653
 
  • F.H. de Sá, H.O.C. Duarte, L. Liu, N. Milas, X.R. Resende
    LNLS, Campinas, Brazil
  
  In this paper we present the on going work of construction of the Sirius impedance budget and instability threshold estimates for several machine operation scenarios.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI041  
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TUPRI043 Analysis of Coupled Bunch Instabilities in BESSY-VSR HOM, cavity, damping, impedance 1659
 
  • M. Ruprecht, P. Goslawski, A. Jankowiak, M. Ries, A. Schälicke, G. Wüstefeld
    HZB, Berlin, Germany
  • T. Weis
    DELTA, Dortmund, Germany
  
  BESSY-VSR, a scheme where 1.5 ps and 15 ps long bunches (rms) can be stored simultaneously in the BESSY II storage ring has recently been proposed*. The strong longitudinal bunch focusing is achieved by superconducting high gradient RF cavities. This paper presents investigations of coupled bunch instabilities driven by HOMs of superconducting multi cell cavities in BESSY-VSR. Analytical calculations and tracking simulations in time domain are performed in the longitudinal and the transverse planes and factors that influence the threshold currents are being discussed. Suitable candidates of cavities which are presently available or in the phase of design are compared with respect to their instability thresholds.
* G. Wüstefeld, A. Jankowiak, J. Knobloch, M. Ries, Simultaneous Long and Short Electron Bunches in the BESSY II Storage Ring, Proceedings of IPAC2011, San Sebastián, Spain 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI043  
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TUPRI067 Recent Results for the Dependence of Beam Instabilities caused by Electron Clouds at CesrTA due to Variations in Bunch Spacing and Chromaticity electron, positron, damping, controls 1721
 
  • M.G. Billing, K.R. Butler, G. Dugan, M.J. Forster, G. Ramirez, N.T. Rider, K.G. Sonnad, H.A. Williams
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • J.W. Flanagan
    KEK, Ibaraki, Japan
  • R. Holtzapple, K.E. McArdle, M.I. Miller, M.M. Totten
    CalPoly, San Luis Obispo, California, USA
  
  Funding: Work supported by DOE Award DE-FC02-08ER41538, NSF Award PHY-0734867, PHY-1068662 and the Lepton Collider R&D, Coop Agreement: NSF Award PHY-1002467
At the Cornell Electron-Positron Storage Ring Test Accelerator (CesrTA) experiments have been studying the interaction of the electron cloud (EC) with 2.1 GeV stored electron and positron beams. These experiments are intended to characterize the dependence of beam–EC interactions on various beam parameters, such as bunch spacing and vertical chromaticity. Most experiments were performed with 30 or 45-bunch trains, at a fixed current of 0.75 mA/bunch. Earlier experiments with positrons had varied the bunch spacing between 4 and 56 ns at three different vertical chromaticity settings. More recent measurements have included electron-bunch trains to contrast the build up of EC between electron and positron beams. The dynamics of the stored beam was quantified using: a gated Beam Position Monitor (BPM) and spectrum analyzer to measure the frequency spectrum of bunches in the trains; an x-ray beam size monitor to record the bunch-by-bunch, turn-by-turn vertical size of each bunch within the trains. We report on recent ob-servations from these experiments and additional studies, using witness bunches trailing 30 or 45-bunch positron trains, which were used for the generation of the ECs. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI067  
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TUPRI069 NSLS-II Commissioning with 500 MHZ 7-CELL PETRA-III Cavity storage-ring, cavity, accumulation, synchrotron 1724
 
  • A. Blednykh, G. Bassi, W.X. Cheng, J. Choi, Y. Hidaka, S.L. Kramer, Y. Li, B. Podobedov, J. Rose, T.V. Shaftan, G.M. Wang, F.J. Willeke, L.-H. Yu
    BNL, Upton, Long Island, New York, USA
  
  The NSLS-II storage ring has been commissioned during Phase 1 with 500 MHz 7-cell PETRA-III RF cavity. In this paper we present our first beam-measured data on instabilities and collective effects with a normal conducting RF system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI069  
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TUPRI072 Status and Performance of Bunch-by-bunch Feedback at BESSY II and MLS synchrotron, operation, diagnostics, beam-loading 1733
 
  • A. Schälicke, P. Goslawski, M. Ries, M. Ruprecht
    HZB, Berlin, Germany
  
  Funding: Work supported by German Bundesministerium für Bildung und Forschung and Land Berlin.
Bunch-by-bunch feedback systems provide an important component in the reliable operation of electron storage rings. Modern digital bunch-by-bunch feedback systems allow efficient mitigation of multi-bunch instabilities, and at the same time offer valuable beam diagnostics. In this contribution, setup and performance of the bunch-by-bunch feedback systems at BESSY II and the MLS are presented. Longitudinal and transverse instabilities are studied under different machine conditions. The developed data analysis techniques and experimental measurements are discussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI072  
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TUPRI073 Impact of Simplified Stationary Cavity Beam Loading on the Longitudinal Feedback System for SIS100 synchrotron, cavity, beam-loading, controls 1736
 
  • K. Groß, H. Klingbeil, D.E.M. Lens
    TEMF, TU Darmstadt, Darmstadt, Germany
  • H. Klingbeil
    GSI, Darmstadt, Germany
  • D.E.M. Lens
    TU Darmstadt, RTR, Darmstadt, Germany
  
  Funding: Work supported by the German Federal Ministry of Education and Research (BMBF) under the project 05P12RDRBF.
The main synchrotron SIS100 of the Facility for Antiproton and Ion Research (FAIR) will be equipped with a bunch-by-bunch feedback system to damp longitudinal beam oscillations. In the basic layout, one three-tap finite impulse response (FIR) filter will be used for each single bunch and oscillation mode. The detected oscillations are used to generate a correction voltage in dedicated broadband radio frequency (RF) cavities. The digital filter is completely described by two parameters, the feedback gain and the passband center frequency, which have to be defined depending on the longitudinal beam dynamics. In earlier works*, the performance of the closed loop control with such an FIR-filter was analyzed and compared to simulations and measurements with respect to the damping of coherent dipole and quadrupole modes, the first modes of oscillation. This contribution analyzes the influence of cavity beam loading on the closed loop performance and the choice of the feedback gain and passband center frequency to verify future high current operation at FAIR.
* H. Klingbeil et al., IEEE Trans. Nuc. Sci., Vol. 54, No. 6, 2007 and D. Lens et al., Phys. Rev. STAB 16, 032801, 2013. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI073  
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TUPRI074 First Results of the New Bunch-by-bunch Feedback System at ANKA injection, operation, insertion, insertion-device 1739
 
  • E. Hertle, N. Hiller, E. Huttel, B. Kehrer, A.-S. Müller, A.-S. Müller, N.J. Smale
    KIT, Eggenstein-Leopoldshafen, Germany
  • M. Höner
    DELTA, Dortmund, Germany
  • D. Teytelman
    Dimtel, San Jose, USA
  
  A new digital three dimensional fast bunch by bunch feedback system has been installed and commissioned at ANKA. Immediate improvements to stored current and lifetime were achieved for normal user operation. For this, the feedback has to be running during the injection and the energy ramp to 2.5 GeV. Additionally, the feedback system was also incorporated into the diagnostic tool-set at ANKA and opened up new possibilities of automated and continuous measurements of certain beam parameters. The system can operate in different modes such as the low alpha operation mode, which has different requirements on the feedback system compared to normal user operation. Results on the various aspects will be presented as well as future improvements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI074  
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TUPRI075 Beam Orbit Stability at Elettra injection, electron, storage-ring, operation 1742
 
  • G. Gaio, S. Cleva, E. Karantzoulis, S. Krecic, M. Lonza
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  
  The top-up operation established since 2010 at the Elettra third-generation synchrotron light source has solved the problems related to thermal drifts and beam current dependence, and a series of feedback loops acting on the machine optics and radio-frequency systems made easier to setup and operate the ring. Those systems together with the fast orbit feedback in operation since 2007, contributed to a very high electron beam orbit stability. A description of the active systems and their performance, future perspectives as well as some still open issues will be presented and discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI075  
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TUPRI077 Stabilization of Mid-infrared FEL by Feedback Controls FEL, electron, klystron, gun 1745
 
  • H. Zen, M. Inukai, T. Kii, K. Masuda, M. Mishima, H. Negm, H. Ohgaki, K. Okumura, K. Takami, K. Torgasin, Y. Tsugamura, K. Yoshida
    Kyoto University, Kyoto, Japan
  
  A Mid-Infrared Free Electron Laser facility, KU-FEL* has been developed for energy related sciences. A beam position monitor and feedback system was introduced to stabilize the FEL output power and wavelength. The long term stability of FEL power and wavelength has been drastically improved by the feedback control. The developed feedback system and its performance will be reported in the conference.
*H. Zen, et al., Infrared Physics & Technology, vol.51, 382-385. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI077  
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TUPRI078 Fast Orbit Feedback Application at MAX IV and SOLARIS Storage Rings storage-ring, controls, brilliance, status 1748
 
  • P. Leban, E. Janezic
    I-Tech, Solkan, Slovenia
  • M. Sjöström
    MAX-lab, Lund, Sweden
  
  A common Fast Orbit Feedback (FOFB) application is planned for the new storage rings at MAX IV laboratory and SOLARIS. The application will run in the Beam Position Monitor (BPM) electronics (Libera Brilliance+). Global orbit data concentration will be conducted inside the gigabit data exchange (GDX) modules with a Virtex6 field programmable gate array, which will be daisy-chained around the storage ring. The feedback calculation algorithm is based on the Singular Value Decomposition (SVD) – the PI controller will be applied in the modal space for individual eigenmodes. The calculations will be distributed over all GDX modules to reduce overall latency. Each GDX module will calculate setpoints for four correctors, horizontal or vertical. The new setpoints will be sent directly to the magnet power supply controllers over a serial point-to-point link. This article presents details on FOFB implementation and control topology.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI078  
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TUPRI080 Emittance Optimisation in the Drive Beam Recombination Complex at CTF3 emittance, linac, controls, simulation 1754
 
  • D. Gamba, F. Tecker
    CERN, Geneva, Switzerland
  • D. Gamba
    JAI, Oxford, United Kingdom
  
  According to the Conceptual Design Report, the power to accelerate the main colliding beams of CLIC is taken from parallel high intensity (100 A), low energy (2.37 GeV) beams. These beams are generated by long trains, accelerated by conventional klystrons and then time-compressed in the so called Drive-Beam Recombination Complex (DBRC). A scaled version of the DBRC has been built at the CLIC Test Facility (CTF3) at CERN in order to prove its principle and study any arising feasibility issues. One of the main constraints is the emittance control during the recombination process. This work presents an overview of the studies ongoing at CTF3, keeping in view possible improvements of the nominal CLIC design. In particular, a generic feedback algorithm to solve (quasi-)linear systems has been implemented and used in order to optimise the process by tuning the energy of the beam and steer the orbits in the different lines, as well matching the design dispersion. Current results and possible room for further optimisation will be shown.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI080  
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TUPRI081 Feed-forward and Feedback Schemes applied to the Diamond Light Source Storage Ring photon, optics, storage-ring, undulator 1757
 
  • M.T. Heron, M.G. Abbott, M.J. Furseman, D.G. Hickin, E.C. Longhi, I.P.S. Martin, G. Rehm, W.A.H. Rogers, A.J. Rose, B. Singh
    DLS, Oxfordshire, United Kingdom
  
  Since initial operation for users in Jan 2007, Diamond Light Source has developed to support a suite of 22 experimental stations. These stations have resulted in the installation of 24 undulators and two superconducting wigglers in the storage ring. To preserve optics, tune and coupling with the operation of these devices has necessitated the implementation of a number of feed-forward and feedback schemes. The implementation and operation of these correction schemes will be described.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI081  
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TUPRI082 Active Optics Stabilisation Measures at the Diamond Storage Ring injection, quadrupole, optics, storage-ring 1760
 
  • I.P.S. Martin, R. Bartolini, R.T. Fielder, M.J. Furseman, E.C. Longhi, G. Rehm, W.A.H. Rogers, A.J. Rose, B. Singh
    DLS, Oxfordshire, United Kingdom
  • R. Bartolini
    JAI, Oxford, United Kingdom
  
  The Diamond storage ring is currently operated with 26 insertion devices (IDs), including 14 in-vacuum IDs, 7 APPLE-II type helical undulators and 2 superconducting wigglers. Differences in the design, construction and operation of these devices, combined with different Twiss parameters at the source point, mean each has a different impact on tune stability and beta-beat. In turn, these parameters affect the on and off-momentum dynamic aperture and ultimately impact on the injection efficiency and lifetime. Another source of optics variation arises from the coherent tune shift with current, which when injecting from zero current causes the tune to span the available good-tune region. In this paper we discuss the difficulties of operating the Diamond storage ring in top-up mode with these effects, and present the various measures taken to stabilise the storage ring optics.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI082  
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TUPRI083 A Fast Optics Correction for the Diamond Storage Ring optics, quadrupole, storage-ring, emittance 1763
 
  • I.P.S. Martin, M.G. Abbott, R. Bartolini, M.J. Furseman, G. Rehm
    DLS, Oxfordshire, United Kingdom
  • R. Bartolini
    JAI, Oxford, United Kingdom
  
  Since March 2013, the Diamond storage ring has been operated with a target vertical emittance of 8 pm.rad. This condition is achieved by first applying a LOCO* optics correction with IDs set to their typical gaps, then offsetting the skew quadrupole magnets in order to increase the vertical emittance again to the desired value. Whilst a feedback application** is able to stabilise the vertical emittance during ID gap and phase changes in the short to medium term, regular applications of LOCO are still required to maintain good coupling control in the longer term. In this paper we describe measures taken to speed up the optics correction procedure, including a fast orbit response matrix measurement, a reduction of the number of magnets used to measure the data, and a distribution of the LOCO calculations to run in parallel.
* J. Safranek, Nucl. Inst. Meth. A, 338, (1997)
** I.P.S. Martin, et al., IPAC 2013, MOPEA071, www. JACoW.org 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI083  
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TUPRI085 Development of a 4 GS/s Intra-bunch Instability Control System for the SPS - Next Steps controls, kicker, pick-up, simulation 1766
 
  • J.D. Fox, J.M. Cesaratto, J.E. Dusatko, K.M. Pollock, C.H. Rivetta, O. Turgut
    SLAC, Menlo Park, California, USA
  • S. De Santis
    LBNL, Berkeley, California, USA
  • W. Höfle, G. Kotzian, U. Wehrle
    CERN, Geneva, Switzerland
  
  Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research Program (LARP).
We present the expanded system architecture in development for the control of intra-bunch instabilities in the SPS. Earlier efforts concentrated on validating the performance of a single-bunch demonstration processor. This minimal system was successfully commissioned at the SPS just prior to the LS1 shutdown. The architecture is now in expansion for more complex functionality, specifically multi-bunch control, control during energy ramps, and the expansion of the system front-end dynamic range with more sophisticated orbit offset techniques. Two designs of wideband kicker are being developed for installation and evaluation with the beam. With these GHz bandwidth devices and new RF amplifiers we anticipate being able to excite and control internal motion of the beam consistent with modes expected for Ecloud and TMCI effects. We highlight the expanded features, and present strategies for verifying the behavior of the beam-feedback system in the next series of machine measurements planned after the LS1 shutdown. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI085  
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TUPRI086 Feedback System Design Techniques for Control of Intra-bunch Instabilities at the SPS electron, controls, damping, optics 1769
 
  • C.H. Rivetta, J.M. Cesaratto, J.E. Dusatko, J.D. Fox, O. Turgut
    SLAC, Menlo Park, California, USA
  • W. Höfle, G. Kotzian, K.S.B. Li
    CERN, Geneva, Switzerland
  
  Funding: Work supported by the U.S. Department of Energy under contract # DE-AC02-76SF00515 and the US LHC Accelerator Research Program (LARP).
The feedback control of intra-bunch instabilities driven by electron-clouds or strong head-tail coupling requires bandwidth sufficient to sense the vertical position and apply multiple corrections within a nanosecond-scale bunch. These requirements impose challenges and limits in the design and implementation of the feedback system. This paper presents model-based design techniques for feedback systems to address the stabilization of the transverse bunch dynamics. These techniques include in the design the effect of noise and signals perturbing the bunch motion. Different controllers are compared based on stability margins and equivalent noise gain between input-output of the processing channel. The controller design uses as example the bunch dynamics defined by the SPS ring including the Q20 optics. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI086  
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TUPRI087 A Wideband Slotted Kicker Design for SPS Transverse Intra-bunch Feedback kicker, impedance, coupling, interface 1772
 
  • J.M. Cesaratto, J.D. Fox, C.H. Rivetta
    SLAC, Menlo Park, California, USA
  • D. Alesini, A. Gallo, M. Zobov
    INFN/LNF, Frascati (Roma), Italy
  • S. De Santis
    LBNL, Berkeley, California, USA
  • W. Höfle
    CERN, Geneva, Switzerland
  
  Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research Program (LARP) and by the EU FP7 HiLumi LHC - Grant Agreement 284404.
In order for the SPS to meet the beam intensity demands for the HL-LHC upgrade, control and mitigation of transverse beam instabilities caused by electron cloud and TMCI will be essential. For this purpose a wideband intra-bunch feedback method has been proposed, based on a 4 GS/s front end data acquisition and processing, and on a back end frequency response extending to at least 1 GHz. A slotted type kicker, similar to those used for stochastic cooling, as well as an array of stripline kickers have been considered as the terminal elements of the feedback system. A slotted TEM type kicker has been designed fulfilling the bandwidth and kick strength requirements for the SPS application. In this paper we present an updated version of the design and electromagnetic characteristics, leading into the mechanical design and construction of the kicker occurring later this year. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI087  
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WEZA01 Towards an International Linear Collider: Experiments at ATF2 emittance, optics, sextupole, quadrupole 1867
 
  • K. Kubo
    KEK, Ibaraki, Japan
  
  For linear colliders, realizing extremely small and stable beam is essentially important. At ILC (International Linear Collider), designed vertical beam size and required position stability at the interaction point is nanometer level. In ATF (Accelerator Test Facility) at KEK, study of the final focus system has been performed using small emittance beams extracted from the damping ring. The project is called ATF2. The ATF2 beam line is designed as a prototype of the final focus system of ILC, with basically the same optics, similar beam energy spread, natural chromaticity and tolerances of magnetic field errors. Its design, construction and operation have been performed as an international collaboration. We have demonstrated the local chromatic correction method, which will be used in ILC, and observed the vertical beam size about 55 nm. Test and demonstration of intra-pulse orbit feedback has been successfully performed in the middle of the ATF2 beam line. For demonstration of nm level stable beam, high resolution beam position monitors were installed around the focal point. Here, we report our achievement, status and future plans.  
slides icon Slides WEZA01 [1.453 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEZA01  
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WEOBB01 Design and Performance of the Optical Fiber Length Stabilization System for SACLA laser, controls, timing, experiment 1906
 
  • H. Maesaka, T. Ohshima, Y. Otake
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
  • S. Matsubara
    JASRI/SPring-8, Hyogo, Japan
  
  The x-ray free electron laser facility, SACLA, requires timing synchronization accuracies of less than 50 fs for acceleration rf components and less than 10 fs for pump-and-probe user experiments. Although a stable timing distribution system with optical fiber cables was constructed*, a timing drift of more than 100 fs has been observed after the transmission of about 100 m**. In order to suppress optical fiber length drift, we developed and installed an optical fiber length stabilization system with a Michelson interferometer. A frequency-stabilized laser with a wavelength of 1.5 um is transmitted together with a timing signal and it is reflected back to the interferometer. The length signal from the interferometer is fed back to a fiber stretcher for fiber length control. A prototype system showed that the length of a 1km-long optical fiber in a feedback loop was stabilized within 0.1 um corresponding to 0.5 fs. From this result, a timing accuracy improvement of pump-and-probe experiments can be expected. In this presentation, the design and basic performance of the optical fiber length stabilization system and the operational experience at SACLA will be reported.
* H. Maesaka et al., Proceedings of FEL’08, 352 (2008).
** H. Maesaka et al., Proceedings of FEL’12, 325 (2012).
 		 
slides icon Slides WEOBB01 [2.673 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEOBB01  
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WEPME062 A New Digital LLRF System for a Fast Ramping Storage Ring cavity, LLRF, operation, injection 2418
 
  • M. Schedler, F. Frommberger, W. Hillert, D. Proft, D. Sauerland
    ELSA, Bonn, Germany
  • D. Teytelman
    Dimtel, San Jose, USA
  
  At the Electron Stretcher Facility ELSA of Bonn University, an upgrade of the maximum stored beam current from 20 mA to 200 mA is planned. The storage ring operates applying a fast energy ramp of 6 GeV/s from 1.2 GeV to 3.5 GeV and a slow extraction afterwards over a few seconds to the hadron physics experiments. The intended upgrade is mainly limited by the coupled-bunch instabilities and the ability of bunch-by-bunch feedback systems to suppress such instabilities. In order to achieve optimum bunch-by-bunch feedback performance, the beam phase with respect to the master oscillator and the synchrotron frequency have to stay constant. This paper reports on a new high performance low level RF (LLRF) system. The system stabilizes the cavity field and is capable of executing fast voltage and phase ramps. The LLRF uses FPGA-based digital signal processing and includes cavity tuner control as well as fast interlocks and extensive diagnostics.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME062  
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WEPME064 Comparison of an Analytical Model for Lossy Transmission Lines with Measurement Data impedance, LLRF, radio-frequency, network 2424
 
  • N. Schmitt
    TEMF, TU Darmstadt, Darmstadt, Germany
  • H. Klingbeil
    GSI, Darmstadt, Germany
  
  This paper deals with the analytical modeling of lossy coaxial transmission lines in the frequency range from 100 kHz to 50 MHz with focus on corrugated coaxial lines with polyethylene foam as dielectric. The considered transmission lines are used in low-level radio frequency (LLRF) systems (< 5 MHz) at GSI. These applications require a high precision in amplitude and phase for the transmitted signals where a detailed knowledge of the line properties is of significant interest. As the corresponding data sheets do not provide appropriate data, the necessary data have been computed. The obtained results from the purely analytical model were then compared with previous measurements for validation purposes.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME064  
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WEPME070 Plans for the Implementation of an Intra-pulse Feedback on the Fermi Linac LLRF System LLRF, klystron, linac, controls 2441
 
  • M. Milloch, A. Fabris, F. Gelmetti, M. Predonzani
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  
  FERMI is a single-pass linac-based FEL user-facility covering the wavelength range from 100 nm (12 eV) to 4 nm (310 eV) and is located next to the third generation synchrotron radiation facility Elettra in Trieste, Italy. The 1.5 GeV S-band linac is composed of fifteen 3 GHz 45 MW peak RF power plants powering the gun, sixteen accelerating sections and the RF deflectors. The requirements on beam quality impose tight specifications on the stability of the electromagnetic fields that can be achieved only installing high reliable and high performance state of the art LLRF systems. While these requirements are presently met by the system installed, the on-going upgrade of the processing board with the final one will allow to add new functionalities of the system. One of the possible developments is the implementation of an intra-pulse feedback that will allow to apply the corrections inside the RF pulse. This paper provides an overview of the additional benefits that could be achieved and discusses the requirements and the constraints for the implementation in the machine.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME070  
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WEPME072 Performance of the Digital LLRF System at the cERL LLRF, cavity, controls, linac 2447
 
  • F. Qiu, D.A. Arakawa, H. Katagiri, T. Matsumoto, S. Michizono, T. Miura
    KEK, Ibaraki, Japan
  
  A digital low-level radio frequency (LLRF) system has been developed and evaluated at compact Energy Recovery Linac (cERL) in High Energy Accelerator Research Organization (KEK), Japan. A total of three two-cell cavities were installed for the injector, and two nine-cell cavities were installed for the main linac. The required RF stabilities for these cavities are 0.1% rms in amplitude and 0.1° rms in phase. To satisfy these requirements, we survey feedback parameters such as the proportional and integral (PI) gains. Furthermore, we evaluated the beam energy fluctuation due to the vector-sum controlling error between the cavities injectors 2 and 3. Finally, we present the performance of the LLRF system that was realized in the beam commissioning. This paper describes the current status of the LLRF system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME072  
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WEPME073 Performance of RF System for Compact-ERL Main Linac at KEK cavity, controls, linac, LLRF 2450
 
  • T. Miura, M. Akemoto, A. Akiyama, D.A. Arakawa, S. Fukuda, H. Honma, H. Katagiri, T. Matsumoto, H. Matsushita, S. Michizono, H. Nakajima, K. Nakao, F. Qiu, H. Sakai, T. Shidara, T. Takenaka, K. Umemori, Y. Yano
    KEK, Ibaraki, Japan
  
  The construction of compact ERL in the first stage has been completed in the end of 2013. The rf commissioning in main-linac has been started. The main-linac consists of two nine-cell cavities. The loaded Q is high, ~107. As the rf power sources, a solid state power amplifier and an inductive output tube (IOT) has been used for two cavities, respectively. The RF field and tuner have been successfully controlled by using micro-TCA digital feedback board. This paper reports about the RF commissioning and the performance.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME073  
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WEPME078 Experimental Test of the Prototype LLRF Systems for PAL-XFEL LLRF, klystron, target, impedance 2462
 
  • J. Hu, H. Heo, J.H. Hong, W.H. Hwang, H.-S. Kang, H.-S. Lee, C.-K. Min
    PAL, Pohang, Kyungbuk, Republic of Korea
  
  Two prototype LLRF systems were developed in collaboration with Pohang Accelerator Laboratory(PAL) and domestic companies. They are focused on the control of single klystron system to obtain mainly analogue performance. The low power test of the developed LLRF showed good performance previously. We experimentally tested LLRF in the klystron systems to see performance in the high power situation. They showed performance around the prototype specification for short time and relatively long time. During test some bugs are discovered and fixed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME078  
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WEPRI027 Performance Evaluation of ERL Main Linac Tuner linac, cavity, operation, controls 2534
 
  • K. Enami, D.A. Arakawa, T. Furuya, S. Michizono, T. Miura, F. Qiu, H. Sakai, M. Satoh, K. Shinoe, K. Umemori
    KEK, Ibaraki, Japan
  • E. Cenni
    Sokendai, Ibaraki, Japan
  • M. Sawamura
    JAEA, Ibaraki-ken, Japan
  
  cERL project is now progressing. We are carrying on R&D for cERLmain linac consisted of 1.3GHz superconductive cavity. We evaluate slide jack tuner, which is component part of cryomodule. A slide jack tuner has 2 mechanism to tune frequency. One is slide jack mechanism that tunes roughly and the other is piezo mechanism that tunes finely. We carried out basic experiment and cold experiment. We finally confirmed that slide jack tuning system can tuning to target frequency 1.3GHz.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI027  
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WEPRI067 Multi-Physics Analysis of CW Superconducting Cavity for the LCLS-II using ACE3P cavity, simulation, operation, vacuum 2645
 
  • Z. Li, C. Adolphsen, O. Kononenko, T.O. Raubenheimer, C.H. Rivetta, M.C. Ross, L. Xiao
    SLAC, Menlo Park, California, USA
  
  Funding: Work was supported by the U.S. DOE contract DE-AC02-76SF00515 and used the resources of NERSC at LBNL under US DOE Contract No. DE-AC03-76SF00098.
The LCLS-II linac utilizes superconducting technology operating at continuous wave to accelerate the 1-MHz electron beams to 4 GeV to produce tunable FELs. The TESLA 9-cell superconducting cavity is adopted as the baseline design for the linac. The design gradient is approximately 16 MV/m. The highest operating current is 300 μA. Assuming that the RF power is matched at the highest current, the optimal loaded QL of the cavity is found to be around 4·107. Because of the high QL, the cavity bandwidth approaches the background microphonic detuning, and the performance of the cavity is tightly coupled to the mechanical perturbations of the cavity/cryomodule system. The resulting large phase and amplitude variations in the cavity require active feedback to achieve the 0.01% amplitude and phase stability requirements. To understand the cavity RF response and feedback requirements to the microphonics and Lorentz Force detuning, we have developed a simulation model of the RF-mechanical coupled system using parameters obtained with the multi-physics solver ACE3P. We will present the simulation results of the LCLS-II linac under different power feed scenarios and feedback schemes. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI067  
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WEPRI116 Master Oscillator for the European XFEL laser, low-level-rf, timing, detector 2771
 
  • L.Z. Zembala, K. Czuba, B. Gąsowski, D. Sikora
    Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
  • J. Branlard, H. Schlarb, H.C. Weddig
    DESY, Hamburg, Germany
  
  The reference signal outage causes breakdown of the synchronisation in the entire accelerator, which could result in a multi-day break in the operation. Therefore, the Master Oscillator (MO) for the European XFEL has to be redundant, in order to achieve extremely high reliability. The redundancy concept, which provides no interruption in the reference signal, requires phase coherence, fast RF switching and sustaining the RF power with a high-Q filter. These features allow to keep possible signal transitions smooth. Furthermore, the MO has to generate a 1.3 GHz signal of exceptionally good phase noise performance – jitter < 35 fs RMS integrated from 10 Hz to1 MHz. One of the problems in the way are vibrations, which have to be properly isolated to avoid microphonics effects in oscillators. The proposed MO architecture and connection with the RF distribution system is described. A basic prototype is tested and results are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI116  
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THOAA02 Development of a Low-latency, High-precision, Intra-train Beam Feedback System Based on Cavity Beam Position Monitors cavity, kicker, FPGA, controls 2783
 
  • N. Blaskovic Kraljevic, D.R. Bett, P. Burrows, G.B. Christian, M.R. Davis, Y.I. Kim, C. Perry
    JAI, Oxford, United Kingdom
  
  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 an FPGA-based 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 ~ 1nC separated in time by c. 280ns. The system has been used to demonstrate beam stabilisation to below the 100nm level. Results of the latest beam tests, aimed at even higher performance, will be presented.  
slides icon Slides THOAA02 [2.050 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THOAA02  
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THOAA03 Transverse Intra-bunch Feedback in the J-PARC MR kicker, injection, synchrotron, betatron 2786
 
  • K. Nakamura
    Kyoto University, Kyoto, Japan
  • Y.H. Chin, T. Obina, M. Okada, M. Tobiyama
    KEK, Ibaraki, Japan
  • T. Koseki, T. Toyama
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • Y. Shobuda
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  
  We will report the development of a new broadband (bandwidth of around 100MHz) feedback system for suppression of intra-bunch oscillations and reduction of particle losses at the J-PARC Main Ring (MR). A new BPM has been designed based on the exponential coupler stripline type (the diameter of 134 mm and the length of 300 mm) and it is now under fabrication. In this BPM system, the frequency characteristics are corrected using the equalizer as bunch signals are differentiated. The design detail and the performance of the new BPM as well as preparation of newly installed exciter and power amplifiers will be presented. We will also report beam test results of head-tail mode suppression at 3 GeV with the bunch length of 150-250 ns.  
slides icon Slides THOAA03 [1.149 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THOAA03  
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THPRO035 Improving and Maintaining FEL Beam Stability of the LCLS FEL, timing, high-voltage, undulator 2943
 
  • F.-J. Decker, A.L. Benwell, W.S. Colocho, Z. Huang, A. Krasnykh, J.R. Lewandowski, T.J. Maxwell, J. Sheppard, J.L. Turner
    SLAC, Menlo Park, California, USA
  
  Funding: *Work supported by U.S. Department of Energy, Contract DE-AC02-76SF00515.
The beam stability of the Linac Coherent Light Source (LCLS) has seen many improvements over the years and has matured to a state where progress is slow and maintaining the best stability is becoming the main challenge. Single sources which are identified by various means contribute to only about 10 to 20% of the whole jitter power, meaning that their elimination gives only a small improvement of 5 to 10%. New sources need to be identified fast. Especially slow variations of a few seconds to minutes time scale are often hidden and partially corrected by feedback systems. A few episodes of increased jitter have shown the limitations of some of the feedback systems. Stability for all dimensions, transverse, longitudinal, and intensity are presented. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO035  
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THPRO105 MTCA.4 Module for Cavity and Laser Piezo Operation laser, cavity, high-voltage, controls 3140
 
  • K.P. Przygoda, J. Branlard, M. Felber, C. Gerth, M. Heuer, U. Mavrič, P. Peier, H. Schlarb, B. Steffen
    DESY, Hamburg, Germany
  • T. Kozak, P. Prędki
    TUL-DMCS, Łódź, Poland
  
  A MicroTCA.4 (MTCA.4) compliant Piezo Driver (DRTM-PZT4)* has been developed to drive piezoelectric-based actuators used in accelerator instrumentation applications. More specifically, it is used for superconducting cavities fine tuning, synchronization of pulsed lasers and stabilization of fiber links. This paper briefly presents the designed system requirements and discusses the main hardware issues. The Piezo Driver performance measurements are also discussed. The first results of the prototype hardware usage for laser locking** to an external RF source and fiber link stabilization are summarized.
*K. Przygoda et all.,“MTCA.4 Compilant Piezo Driver RTM for Laser Synchronization”,MIXDES'13**U. Mavric et. all, "Precision Synchronization of Optical Lasers based on MTCA.4 Electronics", IBIC'13 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO105  
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THPME017 Electromechanical Analysis of SCDTL Structures cavity, coupling, proton, linac 3250
 
  • M. Ciambrella, F. Cardelli, M. Migliorati, A. Mostacci, L. Palumbo
    URLS, Rome, Italy
  • L. Ficcadenti, V. Pettinacci
    INFN-Roma, Roma, Italy
  • L. Picardi, C. Ronsivalle
    ENEA C.R. Frascati, Frascati (Roma), Italy
  
  The Side Coupled Drift Tube Linac (SCDTL) is a 3 GHz accelerating structure for proton therapy linac designed for TOP-IMPLART, an Intensity Modulated Proton Linear Accelerator for Radio-Therapy. The structure is made up of short DTL accelerating tanks for low current proton beams, coupled by side coupling cavities. The purpose of this paper is to report on the analysis of electromagnetic and the thermo-mechanical behavior for the SCDTL structure. The 3D electromagnetic analysis is used to derive the power dissipation on the structure; then one can infer the temperature distribution and deformation field in order to eventually evaluate their feedback on the electromagnetic properties of the structure as, for instance, the cavity resonant frequency shift. Such a "multi-physics'' analysis has been performed for different supporting stem geometries in order to optimize the shunt impedance and the R/Q for SCDTL cavities.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME017  
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THPME065 Beam Test of the CERN PSB Wide-band RF System Prototype in the J-PARC MR cavity, impedance, beam-loading, extraction 3385
 
  • F. Tamura
    JAEA/J-PARC, Tokai-mura, Japan
  • K. Hasegawa, C. Ohmori, M. Yoshii
    KEK, Tokai, Ibaraki, Japan
  • M.M. Paoluzzi
    CERN, Geneva, Switzerland
  
  In the framework of the LHC Injectors Upgrade project (LIU), a complete replacement of the existing narrow-band rf systems of CERN PSB with wide-band magnetic alloy (MA) loaded rf systems is in progress. A single gap MA loaded rf system prototype, which uses solid-state power amplifier and includes fast rf feedback for beam loading compensation, has been installed in the J-PARC MR to investigate the system behavior with high intensity proton beams. We report the wake voltage measurement results with and without fast rf feedback. In addition to the fast feedback, the rf feedforward method is under consideration to compensate the heavy beam loading more effectively. Preliminary beam test results with feedforward are also presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME065  
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THPME099 Synchrotron Radiation Diagnostics Performance at ELSA diagnostics, synchrotron, synchrotron-radiation, radiation 3471
 
  • M.T. Switka, F. Frommberger, P. Hänisch, W. Hillert, D. Proft, M. Schedler, S. Zander
    ELSA, Bonn, Germany
  
  Funding: Work funded by the DFG within SFB/TRR16.
The pulse stretcher ring ELSA delivers polarized and non-polarized electrons with an adjustable beam energy of 0.5 - 3.5 GeV to external experimental stations. To meet the growing demands of the user community regarding beam intensity and quality, the upgrade of vital accelerator components is an ongoing process. This includes the improvement of the beam diagnostics in order to resolve and monitor intensity and quality limiting effects. ELSA has recently been equipped with a diagnostic synchrotron radiation beamline housing a streak camera as main beam imaging device. It extends the diagnostics capabilities into the picosecond temporal resolution regime and captures fast longitudinal and transverse beam dynamics. The obtained measurements provide crucial feedback for further machine optimization. The overall performance of the streak camera system and machine relevant measurements are presented. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME099  
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THPME104 Investigation of Beam Instabilities at DELTA using Bunch-by-bunch Feedback Systems synchrotron, damping, storage-ring, booster 3486
 
  • M. Höner, S. Hilbrich, H. Huck, M. Huck, S. Khan, C. Mai, A. Meyer auf der Heide, R. Molo, H. Rast, M. Sommer, P. Ungelenk
    DELTA, Dortmund, Germany
  
  Funding: Work supported by the BMBF (05K13PEC).
At the 1.5-GeV electron storage ring DELTA operated by the TU Dortmund University as a synchrotron radiation user facility, bunch-by-bunch feedback systems are in use for electron beam diagnostics and for the suppression of multibunch instabilities. An automatic readout of bunch position data allows a real-time modal analysis during machine operation. An excitation of particular multibunch modes enables the determination of growth and damping times for all modes independently. Further investigations of beam stability and natural damping times of all modes even below the instability threshold have been performed. In addition, first bunch-by-bunch data taken from the booster synchrotron are shown. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME104  
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THPME130 Development of New Data-taking System for Beam Loss Monitors of J-PARC MR monitoring, detector, operation, extraction 3547
 
  • K. Satou, N. Kamikubota, T. Toyama
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • S.Y. Yoshida
    Kanto Information Service (KIS), Accelerator Group, Ibaraki, Japan
  
  A new data acquisition system has been developed to improve band-width and dynamic range of the beam loss monitor systems. It consists of isolation current amplifiers with the gain of 1M and the band-width of DC-100kHz, and VME-based 24bit ADCs with the band-width of DC-300kHz and the noise level of 100uV peak to peak. The waveform data of 1MS/s and 1KS/s, and the charge count which is the integrated waveform data are generated and these are compared with alarm levels for the machine protection system. Long-term ground-level stability is essential to monitor residual dose activities. Some beam loss signals include effect of radiations from activated devices, and thus its fractions should be excluded. If the residual dose activities just before the beam injections can be monitored, these fractions would be roughly estimated. Furthermore, on-line monitoring of the residual dose activities after a beam operation will be useful for activation control of the devices at the high level activation area like the collimator and the slow-extraction area. A shot by shot DC offset cancellation is adopted to ensure high ground level stability.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME130  
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THPRI024 Finding Your Happy-User-Index operation, proton, target, electron 3816
 
  • A. Lüdeke
    PSI, Villigen PSI, Switzerland
  
  Reliability is defined as the ability of a system or component to perform its required functions under stated conditions for a specified period of time. If we are talking about accelerator reliability then we have to know what the required functions are. Many accelerator facilities restrict their analysis to the beam availability: how reliable is beam provided to the users? We will show that this metrics is often not fully adequate. Specific metrics can be much more useful to allow you to optimize your facility to the needs of your users. The three accelerator user facilities at PSI will serve as examples for these happy-user-indexes.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI024  
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THPRI025 Accelerator Reliability Reporting at the Swiss Light Source operation, interlocks, injection, insertion 3819
 
  • A. Lüdeke
    PSI, Villigen PSI, Switzerland
  
  Third generation light sources do aim for a very high reliability of the accelerator. This contribution describes the reliability reporting of the Swiss Light Source at the Paul Scherrer Institut, as it has been performed in the past decade. We will highlight the importance of a formal reporting on the accelerator reliability to support the long term optimization of the reliability of an accelerator facility.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI025  
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THPRI070 Tuner System Simulation and Tests for the 201-MHz MICE Cavity cavity, simulation, controls, vacuum 3927
 
  • L. Somaschini
    INFN-Pisa, Pisa, Italy
  • A.J. DeMello, A.R. Lambert, S.P. Virostek
    LBNL, Berkeley, California, USA
  • J.H. Gaynier, R.J. Pasquinelli, D.W. Peterson, R.P. Schultz
    Fermilab, Batavia, Illinois, USA
  • Y. Torun
    Illinois Institute of Technology, Chicago, Illlinois, USA
  
  Funding: Supported by the US Department of Energy Office of Science through the Muon Accelerator Program.
The frequency of MICE cavities is controlled by pneumatic tuners as their operation is impervious to large magnetic fields. The mechanical and RF transfer functions of the tuner were simulated in ANSYS. The first of these tuning systems was assembled and tested at Fermilab. The mechanical response and the RF tuning transfer function have been measured and compared with simulation results. Finally the failure of different actuators has been simulated and tested to predict the operational limits of the tuner. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI070  
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