Keyword: feedback
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MOPMB045 Development of FPGA-based Bunch-by-Bunch Beam Current Monitor FPGA, storage-ring, injection, LabView 193
 
  • Liu, C.S. Liu, Q. Luo, B.G. Sun, Z.R. Zhou
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  Funding: Supported by the National Science Foundation of China 11575181, 11375178. And by the Fundamental Research Funds for the Central Universities WK2310000046, WK2310000056
Bunch-by-bunch (BxB) beam current measurement is an important method to study filling pattern of injection and beam instability threshold for multi-bunch operation storage ring, also, necessary equipment for top-up injection. A high-speed high-precision ADC and FPGA are used to construct the bunch-by-bunch beam current measurement system. FPGA reads data from ADC, and transfer the data to PC via USB. A LabVIEW program is running on PC to process the data, and communicates with other accelerator equipment with EPICS by CA Lab. Besides the bunch-by-bunch beam current measurement, the BxB longitudinal tune is measured by the system, and other potential bunch-by-bunch beam diagnostics study could be done in future, like bunch-by-bunch beam life etc., to improve the performance of the storage ring of Hefei light source. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB045  
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MOPMR058 Precise Beam Orbit Response Measurement with AC Excitation electronics, network, power-supply, storage-ring 380
 
  • W.X. Cheng, K. Ha, Y. Tian, L.-H. Yu
    BNL, Upton, Long Island, New York, USA
  
  Fast correctors at NSLS-II storage ring has broad frequency response (~1kHz bandwidth), together with high accurate BPM 10kHz data makes the broadband fast orbit feedback realistic. With integrated NCO, beam orbit response can be precisely measured while driving the electron beam with AC current. Compared to the normal DC orbit response measurement, this method eliminates the measurement errors due to orbit drift. Accurately measured orbit response matrix can be used to characterize the machine lattice. Fast corrector frequency responses have been measured using the same method, by scanning the excitation frequency. This information can be used to optimize the fast orbit feedback control loop.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR058  
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MOPMY003 Transient Beam Loading Effects in RF Systems in JLEIC electron, cavity, klystron, controls 518
 
  • H. Wang, J. Guo, R.A. Rimmer, S. Wang
    JLab, Newport News, Virginia, USA
  
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The pulsed electron bunch trains generated from the Continuous Electron Beam Accelerator Facility (CEBAF) linac to inject into the proposed Jefferson Lab Electron Ion Collider (JLEIC) e-ring will produce transient beam loading effects in the Superconducting Radio Frequency (SRF) systems that, if not mitigated, could cause unacceptably large beam energy deviation in the injection capture, exceed the energy acceptance of CEBAF's recirculating arc. In the electron storage ring, the beam abort or ion clearing gaps or uneven bucket filling can cause large beam phase transients in the (S)RF cavity control systems and even beam loss due to Robinson instability. We have first analyzed the beam stability criteria in steady state and estimate the transient effect in Feedforward and Feedback RF controls. Initial analytical models for these effects are shown for the design of the JLEIC e-ring from 3GeV to 12GeV. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY003  
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MOPMY011 LLRF System Performance during SC Cavity Conditioning at STF KEK LLRF, cavity, controls, FPGA 536
 
  • S.B. Wibowo
    Sokendai, Ibaraki, Japan
  • T. Matsumoto, S. Michizono, T. Miura, F. Qiu
    KEK, Ibaraki, Japan
  
  High Energy Accelerator Research Organization (KEK) is now developing a digital low-level radio frequency (LLRF) control system based on digital feedback control at superconducting RF test facility (STF). The goal is to achieve the amplitude and phase stability of the accelerating field in the superconducting accelerator. Testing and evaluation of the digital LLRF system were conducted during the cavity conditioning performed between October and December 2015 to determine the level of performance. To enable cavity signal monitoring, direct sampling system was constructed and evaluated.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY011  
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MOPMY016 Quadrature Directional Coupling Method for Precise RF Power Measurement coupling, radio-frequency, controls, experiment 549
 
  • B. Du, G. Huang, L. Lin, Y.T. Liu, Z. Zhao
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  The directional coupler is used in the RF transmission and distribution system of accelerator, to measure the forward and backward power. Due to the finite directional isolation of the coupler (20-30dB normally), the crosstalk exists between the bi-directional coupling output signals. For the typical isolation of 26dB, if the bi-directional crosstalk signals are in- or anti- phase, the error of input or reflected power measurement is 10% in case of total reflection, whilst the error of reflected power measurement is 100% in case of VSWR 1.1. A method of quadrature directional coupling measurement is developed to solve the isolation problem. A pair of directional couplers with 90° phase difference are employed to measure the RF power. The influence of the directional crosstalk would be reduced significantly by processing the measurement data. The prototype of quadrature directional couplers is constructed to verify this method. The results showed that the measurement accuracy of quadrature coupler pair after data process is better than 2% for forward measurement, even if the error of single coupler is over 6%. The paper also analyses the error caused by non-ideal quadrature.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY016  
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MOPMY033 Effect of Bandwidth of Low Level Radio Frequency System on the Instability of an Electron Beam LLRF, cavity, synchrotron, electron 570
 
  • Z.K. Liu, L.-H. Chang, M.H. Chang, L.J. Chen, PY. Chen, F.-T. Chung, M.-C. Lin, C.H. Lo, C.L. Tsai, M.H. Tsai, Ch. Wang, M.-S. Yeh, T.-C. Yu
    NSRRC, Hsinchu, Taiwan
  
  The analog Low Level Radio Frequency (LLRF) system is used at Taiwan Photon Source (TPS) RF system. It is composed of three feedback loops to control the amplitude and phase of accelerating field and the frequency of RF cavity. Instability of electron beam and accelerating field due to the bandwidth of LLRF system were observed during the TPS commissioning. This effect was studied and the results will be presented in this paper.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY033  
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MOPOR012 Study of the Beam-Cavity Interaction in the PS 10 MHz RF System cavity, impedance, simulation, acceleration 618
 
  • G. Favia, H. Damerau, M. Morvillo, C. Rossi
    CERN, Geneva, Switzerland
  • M. Migliorati
    University of Rome "La Sapienza", Rome, Italy
  
  The eleven main accelerating cavities of the Proton Synchrotron (PS) at CERN consist of two ferrite-loaded coaxial λ/4 resonators each. Both resonators oscillate in phase, as their gaps are electrically connected by short bars. They are in addition magnetically coupled via the bias loop used for cavity tuning. The cavities are equipped with a wide-band feedback system, limiting the beam loading, and a further reduction of the beam induced voltage is achieved by relays which short-circuit each half-resonator gap when the cavity is not in use. Asymmetries of the beam induced voltage observed in the two half-cavities indicate that the coupling between the two resonators is not as tight as expected. The total cavity impedance coupling to the beam may be affected differently by the contributions of both resonators. A dedicated measurement campaign with high-intensity proton beam and numerical simulation have been performed to investigate the beam-cavity interaction. This paper reports the result of the study and the work aiming at the development of a model of the system, including the wide-band feedback, which reproduces this interaction.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR012  
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MOPOR013 The PS 10 MHz High Level RF System Upgrade cavity, impedance, network, beam-loading 622
 
  • G. Favia, H. Damerau, V.D. Desquiens, S. Energico, M. Morvillo, D. Perrelet, C. Rossi
    CERN, Geneva, Switzerland
  
  In view of the upgrade of the injectors for the High Luminosity LHC, significantly higher bunch intensity is required for LHC-type beams. In this context an upgrade of the main accelerating RF system of the Proton Synchrotron (PS) is necessary, aiming at reducing the cavity impedance which is the source of longitudinal coupled-bunch oscillations. These instabilities pose as a major limitation for the increase of the beam intensity as planned after LS2. The 10 MHz RF system consists in 11 ferrite loaded cavities, driven by tube-based power amplifiers for reasons of radiation hardness. The cavity-amplifier system is equipped with a wide-band feedback that reduces the beam induced voltage. A further reduction of the beam loading is foreseen by upgrading the feedback system, which can be reasonably achieved by increasing the loop gain of the existing amplification chain. This paper describes the progress of the design of the upgraded feedback system and shows the results of the tests on the new amplifier prototype, installed in the PS during the 2015-16 technical stop. It also reports the first results of its performance with beam, observed in the beginning of the 2016 run.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR013  
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MOPOY006 Preparations for Upgrading the RF Systems of the PS Booster cavity, impedance, operation, emittance 853
 
  • S.C.P. Albright, D. Quartullo, E.N. Shaposhnikova
    CERN, Geneva, Switzerland
  
  The accelerators of the LHC injector chain need to be upgraded to provide the HL-LHC beams. The PS Booster, the first synchrotron in the LHC injection chain, uses three different RF systems (first, second and up to tenth harmonic) in each of its four rings. As part of the LHC Injector Upgrade the current ferrite RF systems will be replaced with broadband Finemet cavities, increasing the flexibility of the RF system. A Finemet test cavity has been installed in Ring 4 to investigate its effect on machine performance, especially beam stability, during extensive experimental studies. Due to large space charge impedance Landau damping is lost through most of the cycle in single harmonic operation, but is recovered when using the second harmonic and controlled longitudinal emittance blow-up. This paper compares beam parameters during acceleration with and without the Finemet test cavity. Comparisons were made using beam measurements and simulations with the BLonD code based on a full PS Booster impedance model. This work, together with simulations of future operation, have provided input for the decision to adopt a fully Finemet RF system.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOY006  
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TUPOR017 Beam-beam Simulation of Crab Cavity with Frequence Dependent Noise for LHC Upgrade luminosity, cavity, simulation, emittance 1691
 
  • J. Qiang
    LBNL, Berkeley, California, USA
  • G. Arduini, Y. Papaphilippou, T. Pieloni
    CERN, Geneva, Switzerland
  • J. Barranco
    EPFL, Lausanne, Switzerland
  
  High luminosity LHC upgrade will improve the luminosity of the current LHC operation by an order of magnitude. Crab cavity as a critical component for compensating luminosity loss from large crossing angle collision and also providing luminosity leveling for the LHC upgrade is being actively pursued. In this paper, we will report on the study of potential effects of the frequence-dependent crab cavity noise on the beam luminosity lifetime using strong-strong beam-beam simulations.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOR017  
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TUPOR023 Investigation of Trapped Resonant Modes in Insertion Devices at the Australian Synchrotron resonance, vacuum, undulator, synchrotron 1710
 
  • R.T. Dowd, M.P. Atkinson, M.J. Boland, G. LeBlanc, Y.E. Tan
    SLSA, Clayton, Australia
  • D. Teytelman
    Dimtel, San Jose, USA
  
  The Australian Synchrotron light Source has 3 variable gap in-vacuum undulators (IVU) in the storage ring. Since installation, these devices have been the source of strong beam instabilities. These instabilities seem to behave as trapped resonant modes of very high Q and high frequency, although a definite source has not been identified. The presence of these instabilities has necessitated operating at unusually high chromaticity for much of the light source's operations. More recently transverse feedback has been able to control the instabilities and recent developments in diagnostics have allowed some investigation of the frequency and mode response of these resonances. The results of this investigation will be presented in this paper.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOR023  
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TUPOR027 Interaction of RF Phase Modulation and Coupled-Bunch Instabilities at the DELTA Storage Ring damping, storage-ring, electron, synchrotron 1720
 
  • M. Sommer, B.D. Isbarn, B. Riemann, T. Weis
    DELTA, Dortmund, Germany
  
  Funding: Work supported by the BMBF under contract no. 05K13PEB.
Analyzing the interaction of RF phase modulation and coupled-bunch instabilities requires a method to determine damping rates of coupled-bunch modes at presence of RF phase modulation. This paper shows, that the common way of using exponential fits to determine damping rates is not viable for high modulation amplitudes. It presents a new method, which is capable of acquiring damping rates of coupled-bunch modes for phase shifts up to 5°, using a bunch-by-bunch feedback system. For this purpose a specific mode is excited by the feedback system and the saturation value, i.e. the maximum excitation, is measured to calculate the damping rate. With this new method, the modulation amplitude of the RF phase modulation is swept from 0° to 5° and it can be shown, that the damping rate is proportional to the square of the modulation amplitude. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOR027  
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TUPOR028 Excitation of Longitudinal Coupled-bunch Oscillations with the Wide-band Cavity in the CERN PS cavity, synchrotron, LLRF, proton 1724
 
  • L. Ventura, M. Migliorati
    INFN-Roma1, Rome, Italy
  • H. Damerau, M. Migliorati, G. Sterbini
    CERN, Geneva, Switzerland
  • M. Migliorati
    University of Rome "La Sapienza", Rome, Italy
  
  Longitudinal coupled-bunch oscillations in the CERN Proton Synchrotron have been studied in the past years and they have been recognized as one of the major challenges to reach the high brightness beam required by the High Luminosity LHC project. In the frame of the LHC Injectors Upgrade project in 2014 a new wide-band Finemet cavity has been installed in the Proton Synchrotron as a part of the coupled-bunch feedback system. To explore the functionality of the Finemet cavity during 2015 a dedicated measurement campaign has been performed. Coupled-bunch oscillations have been excited with the cavity around each harmonic of the revolution frequency with both a uniform and nominal filling pattern. In the following the measurements procedure and results are presented.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOR028  
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TUPOR033 Experimental Study of Single Bunch Instabilities at NSLS-II Storage Ring synchrotron, storage-ring, betatron, lattice 1738
 
  • W.X. Cheng, B. Bacha, G. Bassi, A. Blednykh, B. Podobedov, O. Singh, V. Smalyuk
    BNL, Upton, Long Island, New York, USA
  
  Single bunch instabilities have been observed since the early stage of NSLS-II storage ring commissioning. After installing the super-conducting cavity, the single bunch instability threshold current was similar at 0.7mA. The instability was eventually determined to be due to transverse mode coupling. Microwave instability has been characterized using streak camera bunch profile, horizontal beam sizes at dispersion location and beam spectrums. Microwave instability threshold current dependency on bunch lengths and IUV gaps has been studied. Most recent experimental results will be presented in this paper.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOR033  
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WEPOR001 Beam Studies with a New Longitudinal Feedback System at the ANKA Storage Ring injection, synchrotron, storage-ring, kicker 2658
 
  • E. Blomley, A.-S. Müller, M. Schedler
    KIT, Karlsruhe, Germany
  
  With the now fully commissioned longitudinal feedback system at the ANKA Storage Ring - in addition to the already operational transverse feedback system - the stability throughout the injection process was increased considerably. This opened up the possibility to investigate beam dynamics and limitations during injection more systematically. This paper presents the results of these studies, an overview of the limiting parameters and discusses possible approaches to increase the efficiency of the injection.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR001  
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WEPOR002 Orbit Stabilization for the HLS-II Storage Ring storage-ring, quadrupole, electron, alignment 2661
 
  • W. Xu, J.Y. Li, K. Xuan, H.Y. Zhang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  Hefei Light Source has successfully completed a major upgrade project, which greatly improves the light source performance. As one of the most important criteria, the stability of the beam orbit in the storage ring can greatly influence the overall performance of the light source. In this paper we present our efforts on stabilizing the beam orbit during the commissioning of the HLS-II storage ring. We optimized the performance of the power supplies of the ring corrector magnets. The target beam orbit is obtained by measuring the center of the quadrupole magnets using the beam-based alignment method. We also developed a multi-functional orbit feedback system to keep the beam moving on the golden orbit. With these measures, the beam orbit gets more stable than ten percent of the beam size at the light source points.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR002  
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WEPOR003 Voltage Control for the 4-Th Harmonic Cavity in Hls Storage Ring cavity, controls, storage-ring, EPICS 2664
 
  • K. Xuan, C. Li, J.Y. Li, G. Liu, W. Xu
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  In order to increase the beam lifetime, a 4th harmonic RF cavity was installed in the HLS-II storage ring. The electrical fields in the principle cavity and high harmonic cavity stretch the beam in the longitudinal direction, and increase the beam volume in phase space, leading to a longer Touschek lifetime. Stable electrical voltage in the high harmonic cavity is essential for steady beam stretching and better beam lifetime. To get a stable high voltage in the high harmonic cavity, we develop a method to maintain steady resonance condition in the cavity using a PID scheme. This paper presents the details of this method. The feedback result is also reported.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR003  
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WEPOR004 Fast Orbit Feedback System at the Pls-Ii Storage Ring electron, storage-ring, operation, timing 2667
 
  • S.-C. Kim, W.S. Cho, C. Kim, J.M. Kim, K.R. Kim, E.H. Lee, J. Lee, J.W. Lee, T.-Y. Lee, C.D. Park, G.S. Park, S. Shin, J.C. Yoon
    PAL, Pohang, Kyungbuk, Republic of Korea
  
  Funding: This work is supported by the Ministry of science, ICT and Future Planning, Korea.
The transverse position of the electron beam in the Pohang Light Source-II (PLS-II) is stabilized by the global orbit feedback system. Currently, 2 Hz slow orbit feedback (SOFB) system is operating, and 1 kHz fast orbit feedback (FOFB) system is installed recently. This FOFB system is consists of 96 electron beam position monitors (BPMs), 48 horizontal fast correctors, 48 vertical fast correctors and VME control system. We present the design and implementation of the FOFB system and its test result. Analysis through the simulation is presented and future improvement is discussed 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR004  
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WEPOR005 Ground Motion Compensation using Feed-forward Control at ATF2 ground-motion, quadrupole, controls, extraction 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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WEPOR007 Recent Improvements in Drive Beam Stability in CTF3 klystron, operation, gun, linac 2677
 
  • L. Malina, R. Corsini, D. Gamba, T. Persson, P.K. Skowroński
    CERN, Geneva, Switzerland
  
  The proposed Compact Linear Collider (CLIC) uses a high intensity, low energy drive beam producing the RF power to accelerate the low intensity main beam with 100 MeV/m gradient. This scheme puts stringent requirements on drive beam stability in terms of phase, energy and current. Finding and understanding the sources of jitter plays a key role in their mitigation. In this paper, we report on the recent studies in the CLIC Test Facility (CTF3). New jitter and drift sources were identified and adequate beam-based feed-backs were implemented and commissioned. Finally, we present the resulting improvement of drive beam stability.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR007  
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WEPOR009 Intra-beam IP Feedback Studies for the 380 GeV CLIC Beam Delivery System luminosity, ground-motion, kicker, simulation 2683
 
  • R.M. Bodenstein, P. Burrows, J. Snuverink
    JAI, Oxford, United Kingdom
  • F. Plassard
    CERN, Geneva, Switzerland
  
  In its currently-envisaged initial stage, the Compact Linear Collider (CLIC) will collide beams with a 380 GeV center of mass energy. To maintain the luminosity within a few percent of the design value, beam stability at the interaction point (IP) must be controlled at the sub-nanometer level. To help achieve such control, use of an intra-pulse IP feedback system is planned. With CLIC's very short bunch spacing of 0.5 ns, and nominal pulse duration of 176 ns, this feedback system presents a significant technical challenge. Furthermore, as part of a study to optimize the design of the beam delivery system (BDS), several L* configurations have been studied. In this paper, we will review the IP feedback simulations for the 380 GeV machine for two L* configurations, and compare luminosity recovery performance with that of the original L* configuration in the 3 TeV machine.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR009  
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WEPOR010 Recent Upgrades to the CERN SPS Wideband Intra-bunch Transverse Feedback Processor controls, FPGA, timing, operation 2687
 
  • J.E. Dusatko, J.D. Fox, C.H. Rivetta
    SLAC, Menlo Park, California, USA
  • W. Höfle
    CERN, Geneva, Switzerland
  • O. Turgut
    Stanford University, Stanford, California, USA
  
  In support of the CERN High Luminosity LHC (HL-LHC) upgrade program, a research and development effort has been underway to understand and develop feedback control techniques for mitigating transverse intra-bunch instabilities in the SPS driven by electron cloud and TMCI effects. These effects could be a limiting factor to overall machine performance. A result of this effort has been the development of a very wide band transverse feedback demonstration system. This system has been used for the last several years in machine development studies where we have demonstrated single-bunch stability control of low order intra-bunch modes. In continuation of these efforts, recent upgrades have been performed in all stages of the system, including the feedback processor itself. This paper discusses the upgrades specific to it, including the ability to process multiple proton bunches in the SPS; and also highlights future directions in the development effort.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR010  
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WEPOR033 Progress in the Work on the Tuner Control System of the cERL at KEK controls, LLRF, linac, FPGA 2742
 
  • F. Qiu, T. Matsumoto, S. Michizono, T. Miura
    KEK, Ibaraki, Japan
  • S.B. Wibowo
    Sokendai, Ibaraki, Japan
  
  A compact energy recovery linac (cERL), which is a test machine for future 3 GeV ERL project, was constructed at KEK. Five superconducting (SC) cavities were installed in the injector and main linac of the cERL. The SC cavities in cERL are prone to detuning by disturbances such as microphonics. Therefore, a piezo-based tuner system was used to compensate for the detuning of the SC cavity in the cERL. We have proposed advanced control methods that aim at improving the performance of the cERL tuner systems. In this paper, we present the progress in our work on the cERL tuner systems. The preliminary results of the beam-commissioning are also presented.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR033  
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WEPOR037 Beam Loading Effects in SSRF Storage Ring cavity, storage-ring, beam-loading, LLRF 2755
 
  • Y. Xia, Q. Chang, Z. Li, K. Xu, Zh.G. Zhang, S.J. Zhao, Y.B. Zhao, X. Zheng
    SINAP, Shanghai, People's Republic of China
  
  The beam current in the storage ring of Shanghai Synchrotron Radiation Facility (SSRF) is now normally 240 mA and projected to be raised to 300 mA. Heavy beam loading will be serious and associated Robinson instability needs to be compressed. In this paper, the beam loading effects in SSRF storage ring and methods to increase current limit will be discussed. .  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR037  
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WEPOR040 LLRF Development for PAL-XFEL LLRF, operation, klystron, electron 2761
 
  • J. Hu, W.H. Hwang, H.-S. Kang, H.-S. Lee, C.-K. Min, G. Mun
    PAL, Pohang, Kyungbuk, Republic of Korea
  • J.H. Chang, J.S. Han, Y.S. Kim
    RFPT, Gyeonggi-do, Republic of Korea
  • O.J. Kim, H.S. Lee
    Mobiis Co., Ltd., Seoul, Republic of Korea
  
  PAL-XFEL construction is completed. Now, beam commissioning is ongoing after RF conditioning. The LLRF and SSA systems installed and in normal operation are presented. Those structures, features, characteristics, and performances are described.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR040  
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WEPOR042 LLRF Control of High Loaded-Q Cavities for the LCLS-II cavity, LLRF, controls, linac 2765
 
  • C. Serrano, L.R. Doolittle, G. Huang, A. Ratti
    LBNL, Berkeley, California, USA
  • S. Babel, M. Boyes, B. Hong
    SLAC, Menlo Park, California, USA
  • R. Bachimanchi, C. Hovater
    JLab, Newport News, Virginia, USA
  • B.E. Chase, E. Cullerton, J. Einstein
    Fermilab, Batavia, Illinois, USA
  
  Funding: This work was supported by the LCLS-II Project and the U.S. Department of Energy, Contract DE-AC02-76SF00515
The SLAC National Accelerator Laboratory is planning an upgrade (LCLS-II) to the Linear Coherent Light Source with a 4 GeV CW Superconducting Radio Frequency (SCRF) linac. The nature of the machine places stringent requirements in the Low-Level RF (LLRF) system, expected to control the cavity fields within 0.01 degrees in phase and 0.01% in amplitude, which is equivalent to a longitudinal motion of the cavity structure in the nanometer range. This stability has been achieved in the past but never for hundreds of superconducting cavities in Continuous-Wave (CW) operation. The difficulty resides in providing the ability to reject disturbances from the cryomodule, which is incompletely known as it depends on the cryomodule structure itself (currently under development at JLab and Fermilab) and the harsh accelerator environment. Previous experience in the field and an extrapolation to the cavity design parameters (relatively high QLc≈ 4×107 , implying a half-bandwidth of around 16 Hz) suggest the use of strong RF feedback to reject the projected noise disturbances, which in turn demands careful engineering of the entire system. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR042  
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WEPOR044 Fpga Implementation of a Control System for the LANSCE Accelerator controls, cavity, LLRF, FPGA 2771
 
  • S. Kwon, L.J. Castellano, D.J. Knapp, J.T.M. Lyles, M.S. Prokop, D. Rees, A. Scheinker, P.A. Torrez
    LANL, Los Alamos, New Mexico, USA
  
  As part of the modernization of the Los Alamos Neutron Science Center (LANSCE), a digital low level RF (LLRF) system was designed. The LLRF control system was implemented in a Field Programmable Gate Array (FPGA) using embedded Experimental Physics and Industrial Control System (EPICS) Input Output Controller (IOC) under the Real-Time Executive for Multiprocessor Systems (RTEMS). Proportional-Integral (PI) feedback controller, static beam feedforward controller, and iterative learning controller are implemented on the FPGA. The closed loop system performance was tested with a 10mA peak current proton beam.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR044  
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WEPOR056 Development of a Cw Solid State Amplifier for the Longitudinal Feedback System of Bepcii detector, controls, kicker, HOM 2796
 
  • S. An, Z. Bowen
    PLAI, Nanjing, People's Republic of China
  • J.L. Linling
    ADS, Jiangsu Province, People's Republic of China
  • J.H. Yue
    IHEP, Beijing, People's Republic of China
  • L. Zhang
    Chang'an University, Chang'an, People's Republic of China
  
  A Solid State Amplifier (SSA) has been developed for testing beam feedback system of the BEPCII of the Institute of High Energy Physics (IHEP), CAS. The output power of the SSA is 100 W with a CW frequency range from 1000 MHz to 1250 MHz. After three generations development, the SSA has become a professional power source. The paper has introduced the development of the SSA and the skills used in the SSA.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR056  
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WEPOW037 Bunch Length Measurements with Passive Harmonic Cavities for Non-uniform Fill Patterns in a 100 MHz RF System simulation, storage-ring, cavity, beam-loading 2918
 
  • T. Olsson, S.C. Leemann, P. Lilja
    MAX IV Laboratory, Lund University, Lund, Sweden
  
  The MAX IV facility includes two storage rings operated at 1.5 GeV and 3 GeV, which are both designed to operate with a uniform, multibunch fill pattern. Both rings have a 100 MHz RF system and employ passive harmonic cavities to damp instabilities and increase Touschek lifetime. Recently, a discussion on timing modes at the MAX IV storage rings has been initiated by the user community. Creating opportunities for timing experiments implies operating the rings with other fill patterns than the planned multibunch mode. Such operation can, however, cause transient effects in the passive harmonic cavities which affect the performance of the machine. It is therefore of interest to study the effect on the beam when operating with non-uniform fill patterns. This paper presents bunch length measurements at the 100 MHz MAX II storage ring for fill patterns with gaps. The purpose of the measurements was to evaluate the employed measurement method and simulation codes for future studies of various alternate fill patterns in the MAX IV storage rings.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOW037  
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WEPOW040 Preliminary Beam Test for TPS Fast Orbit Feedback System power-supply, interface, vacuum, electronics 2930
 
  • P.C. Chiu, K.T. Hsu, K.H. Hu, C.H. Huang, C.Y. Liao
    NSRRC, Hsinchu, Taiwan
  
  TPS (Taiwan Photon Source) is a 3 GeV synchrotron light source which had be successfully commissioning with SRF up to 500 Amp in 2015 and scheduled to open user operation in 2016. As most of the 3rd generation light source, the fast orbit feedback system would be adopted to eliminate various disturbances and improve orbit stability. Due to the vacuum chamber material made of aluminum with higher conductivity and lower bandwidth, extra fast correctors mounted on bellows will be used for FOFB correction loop and DC correction of fast correctors would be transferred to slow ones and avoid fast corrector saturation. This report summarizes the infrastructure of the FOFB and the preliminary beam test is also presented.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOW040  
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WEPOW048 Preparations for the Double Double Bend Achromat Installation in Diamond Light Source dipole, sextupole, vacuum, quadrupole 2953
 
  • R.P. Walker, C.A. Abraham, C.P. Bailey, R. Bartolini, P. Coll, M.P. Cox, N.P. Hammond, M.T. Heron, S.E. Hughes, J. Kay, I.P.S. Martin, S.P. Mhaskar, A.G. Miller, A.J. Reed, G. Rehm, E.C.M. Rial, A.J. Rose, A. Shahveh, H.S. Shiers, A. Thomson
    DLS, Oxfordshire, United Kingdom
  • R. Bartolini
    JAI, Oxford, United Kingdom
  
  We present the status of preparations for a major installation in the Diamond storage ring which is due to take place in 2016, namely the conversion of one cell of the ring from a double bend achromat (DBA) structure, to a double-DBA, or DDBA. We present results of measurements of the new narrow bore, high strength, quadrupoles and sextupoles, as well as the four new gradient dipoles. Fabrication of entirely new narrow-gap vacuum vessel strings, a mixture of copper and stainless steel is also described. The status of assembly of the two 7m long girders is presented, as well as other preparatory engineering, power supply, controls and high level software work.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOW048  
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WEPOW052 Multimodal Interaction in the ALS Longitudinal Feedback Kicker RF Cavity cavity, kicker, resonance, impedance 2965
 
  • S. De Santis, K.M. Baptiste, J.M. Byrd, S. Kwiatkowski, T.H. Luo, E.R. Sanmateo, C. Steier, C.A. Swenson
    LBNL, Berkeley, California, USA
  • F. Marcellini
    PSI, Villigen PSI, Switzerland
  
  Funding: The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
RF cavities are essential components in particle accelerators not only for beam acceleration, but also for control purposes (bunch lengthening/shortening, deflecting and crabbing, transverse and longitudinal kickers) and for beam diagnostics (BPM). Normally, only a single resonating mode is actively used, although other modes can be excited by the circulating beam. Cavities used as feedback longitudinal kickers are designed with an axial mode which, appropriately excited, provides a kick to the circulating bunches for maintaining beam stability. To provide the necessary bandwidth this mode has to be strongly damped resulting in quality factors of just a few units. In the longitudinal feedback kicker cavity just installed on the ALS we have detected a second axial mode which, although a few hundreds of MHz below the 1.4 GHz design mode, is also strongly damped and has a shunt impedance high enough to be appreciably excited by the feedback amplifier coupling to the first mode. In this paper we show bench measurements on the cavity and with beam during its commissioning and discuss the interaction of the two modes resulting in a modulation of shunt impedance and phase response. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOW052  
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WEPOW060 Top Off Algorithm Development and Commissioning at NSLS-II injection, operation, storage-ring, target 2988
 
  • R.P. Fliller, A.A. Derbenev, T.V. Shaftan, G.M. Wang
    BNL, Upton, Long Island, New York, USA
  
  Funding: This manuscript has been authored by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
Recently, NSLS-II introduced top off as the standard mode of beam delivery for the users. During top off, we are required to maintain the beam current within ±0.5% of nominal, and the bunch to bunch variation over the train less than 20% for all operating conditions. In this paper, we discuss the algorithm used for top off, simulations of various operating conditions and performance of the algorithm during operations. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOW060  
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WEPOY045 Benchmarking the Beam Longitudinal Dynamics Code BLonD simulation, impedance, synchrotron, injection 3094
 
  • H. Timko, J. F. Esteban Müller, A. Lasheen, D. Quartullo
    CERN, Geneva, Switzerland
  
  The relatively recent Beam Longitudinal Dynamics code BLonD has already been applied to a wide range of studies for all present CERN synchrotrons. Its application area ranges from studies of RF manipulations, over single and multi-bunch interactions with impedance, to the action of feedback loops and RF noise. In this paper, we present benchmarks and comparisons with measurements, theory, or other codes, which have increased greatly the trust in the code. Tests related to bunch-to-bucket transfer, feedback loops, diffusion due to noise injection, as well as collective effects, are presented.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY045  
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THXA01 Overview of Standards for Beam Instrumentation and Control electronics, controls, instrumentation, synchrotron 3139
 
  • N. Hubert
    SOLEIL, Gif-sur-Yvette, France
  
  This presentation provides an overview of progress toward uniform standards in beam control methods and beam instrumentation at accelerator laboratories. Examples of growing standards among the accelerator community are given and the viability of global implementations are reviewed.  
slides icon Slides THXA01 [4.190 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THXA01  
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THOAA01 Identification of Intra-bunch Transverse Dynamics for Model-Based Control Purposes at CERN Super Proton Synchrotron controls, simulation, synchrotron, proton 3145
 
  • O. Turgut, J.E. Dusatko, J.D. Fox, C.H. Rivetta
    SLAC, Menlo Park, California, USA
  • S.M. Rock
    Stanford University, Stanford, California, USA
  
  Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research program (LARP). Research supported by FP7 HiLumi LHC http://hilumilhc.web.cern.ch
The high luminosity upgrade plan for the LHC (HiLumi-LHC) increases the bunch intensity and the ultimate intensities require mitigation of possible intra-bunch instabilities in the SPS. Feedback systems can stabilize intra-bunch dynamics. Model based control has promise to stabilize intra-bunch dynamics but it requires a reduced order model which captures the most significant intra-bunch dynamics. We present methods for the estimation of a multi-input multi-output (MIMO) reduced order model of intra-bunch dynamics based on data generated by nonlinear macro particle simulations (CMAD, HeadTail). These linear models are used to design optimal model-based controllers. We evaluate the effectiveness of the MIMO model-based controllers for future high intensity beam conditions within the nonlinear macro particle simulations. We highlight the use of these techniques to stabilize intra-bunch motion and as an important beam dynamics measurement technique. 		 
slides icon Slides THOAA01 [10.146 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THOAA01  
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THOAA02 The Development of C-Band Cavity Beam Position Monitor with a Position Resolution of Nano Meter cavity, dipole, electronics, operation 3149
 
  • S.W. Jang, E.-S. Kim
    Korea University Sejong Campus, Sejong, Republic of Korea
  • P. Bambade, O.R. Blanco-García, S. Wallon
    LAL, Orsay, France
  • N. Blaskovic Kraljevic, T. Bromwich, P. Burrows
    JAI, Oxford, United Kingdom
  • T. Tauchi, N. Terunuma
    KEK, Ibaraki, Japan
  
  We developed and tested an C-band beam position monitor with position resolution of nano meter in ATF2. The C-band BPM was developed for the fast beam feedback system at the interaction point of ATF in KEK, which C-band beam position monitor called to IPBPM (Interaction Point Beam Position Monitor). The developed IPBPM was measured 26nm with 30% of nominal beam charge of ATF. From the measured beam position resolution, we can expected to 8nm beam position resolution with nominal ATF beam charge condition. In this talk, we will described about the development of IPBPM and the beam test results of nano meter level beam position resolution.  
slides icon Slides THOAA02 [4.806 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THOAA02  
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THOAA03 MicroTCA.4 based Single Cavity Regulation including Piezo Controls cavity, controls, operation, electron 3152
 
  • K.P. Przygoda, H. Schlarb, Ch. Schmidt
    DESY, Hamburg, Germany
  • P. Echevarria
    HZB, Berlin, Germany
  • R. Rybaniec
    Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
  
  We want to summarize the single cavity regulation with MTCA.4 electronics. Presented solution is based on the one MTCA.4 crate integrating both RF field control and piezo tuner control systems. The RF field control electronics consists of RTM for cavity probes sensing and high voltage power source driving, AMC for fast data processing and digital feedback operation. The piezo control system has been setup with high voltage RTM Piezo driver and low cost AMC based FMC carrier. The communication between both control systems is performed using low latency link over the AMC backplane with data throughput up to the 3.125 Gbps. First results from CW operation of the RF field controller and the cavity active resonance control with the piezo tuners are demonstrated and briefly discussed.  
slides icon Slides THOAA03 [2.693 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THOAA03  
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THPMW007 The Design of a New State Space Digital Power Supply Prototype controls, FPGA, power-supply, hardware 3546
 
  • K. Shu, J.X. Zhang
    IHEP, Beijing, People's Republic of China
  
  Based on system identification and DLQR methods, a self-adaptive power supply can be implemented by the new controller structure without any change in power main circuit. Now only some raw tests have been taken which show its stableness, but the State Space Digital Controlling may turned out to be with potential. It makes power supplies with different capability easy to interchange without any more effort on tuning their parameters according to their loads, and can be extended to accommodate MIMO systems.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMW007  
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THPMW015 A Digtal Regulation Controller Prototype for the TPS Booster Power Supplies controls, booster, power-supply, dipole 3570
 
  • B.S. Wang, Y.-C. Chien, Y.T. Li, C.Y. Liu, K.-B. Liu, Y.S. Wong
    NSRRC, Hsinchu, Taiwan
  
  In the newly built TPS (Taiwan Photon Source), the AC power supplies of the Booster ring are required to operate in DC and AC mode with accuracy. Especially in AC mode, during the booster ramping process, the current ramping profiles of the Quadruple Magnets have to track that of the Dipole AC power supply with precise phase and amplitude to maximize the beam energy boost efficiency. At present, analog current commands for all the booster power supplies with relative phase and amplitude information are generated externally. The current ramping profiles are pre-calculated and calibrated in a centralized manner. In this paper, an auto-calibration process using Curve-Fitting algorithm is proposed. In the new process, the current ramping profile data is first stored digitally in each power supply and then outputted to each power supply with a synchronous trigger signal in hope to eliminate the signal integrality problem inherent in analog signals , so that the beam energy boost up could be more reliable and efficient. The new proposed method has been implemented and tested successfully and will be applied to the booster power supplies to test its performance in the future.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMW015  
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THPOR005 Tunnel Level Variation in the SuperKEKB Interaction Region radiation, alignment, luminosity, operation 3774
 
  • M. Masuzawa, T. Adachi, T. Kawamoto
    KEK, Ibaraki, Japan
  
  SuperKEKB is an electron-positron collider, which aims to achieve a peak luminosity 40 times higher than that of KEKB. The vertical beam sizes of both rings are squeezed down to 50 - 60 nm at the interaction point (IP), which accounts for a factor of 20 in the luminosity increase, and the beam currents are doubled from those of KEKB. Tunnel motion can be critical for realizing the collisions of such small beams. A Hydrostatic Leveling System (HLS), which consists of 18 sensors, was installed on both sides of the IP to monitor tunnel level variations continuously. Effects of heavy rain and installation of the radiation shield blocks on the tunnel floor level are clearly seen. The HLS data during construction and SuperKEKB commissioning are reported.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR005  
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THPOR033 Integration and Testing of 3 Consecutive CLIC Two-Beam Modules vacuum, alignment, collider, operation 3856
 
  • A.L. Vamvakas, M. Aicheler, S. Döbert, M. Duquenne, H.M. Durand, M. Sosin, J.I. Väinölä
    CERN, Geneva, Switzerland
  • V. Rude
    ESGT-CNAM, Le Mans, France
  
  CLIC (Compact LInear Collider) is a study of a 50 km long linear electron-positron collider, consisting of ap-proximately 20,000 repetitive 2 m long modules. Micron level manufacturing and alignment tolerances are re-quired for the RF and magnet components due to the nanometre beam size and luminosity goal. The effect of thermal, vacuum and mechanical loads needs to be as-sessed, both in transient and in steady state conditions. The dynamic behaviour of mock-ups was investigated on the prototype two-beam module. Two additional two-beam modules are installed to further investigate the interconnections between them, in a machine-like envi-ronment. The array of three consecutive modules allows for alignment tests of the module sequence, while thermal and vacuum tests can be executed simultaneously. A transportation experiment is foreseen, investigating the feasibility of installing prealigned modules. Finally, new design of components is being tested, based on the expe-rience gathered from the first module and leading to a new generation module.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR033  
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THPOR034 Bunch-by-bunch Position and Angle Stabilisation at ATF based on Sub-micron Resolution Stripline Beam Position Monitors extraction, kicker, operation, linear-collider 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 cavity, kicker, electron, extraction 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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THPOW038 First Results from Two Novel In-vacuum Magnetic Field Measurement Devices as Built at HZB vacuum, undulator, controls, shielding 4028
 
  • J. Bahrdt, H.-J. Bäcker, J. Bakos, H. Bieder, W. Frentrup, A. Gaupp, S. Gottschlich, C. Kuhn, C. Rethfeldt, M. Scheer, B. Schulz
    HZB, Berlin, Germany
  
  The characterization of cryogenic in vacuum permanent magnet undulators with periods less than 20 mm and correspondingly narrow gaps requires new in-vacuum measurement systems. The positioning accuracy of the HZB in-vacuum Hallprobe bench has substantially been improved (a few μm) with appropriate feedback systems. A new in-vacuum cable tray has been developed. Another system for field integral measurements, an in-vacuum moving wire, is under commissioning. Both devices are presented.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW038  
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THPOY018 Main Operation Improvements on Taiwan Light Source operation, power-supply, controls, FPGA 4125
 
  • C.H. Kuo, H.H. Chen, H.C. Chen, K.T. Hsu, S.J. Huang, J.A. Li, C.Y. Liao, M.-C. Lin, Y.K. Lin, Y.-C. Liu
    NSRRC, Hsinchu, Taiwan
  
  With the beam energy of 1.5 GeV, the storage ring of Taiwan Light Source (TLS) in National Synchrotron Radiation Research Center (NSRRC) has provided research service to users for more than twenty years. It takes a lot of efforts to keep this accelerator reliable and to improve its stability. NSRRC has finished the construction and commissioning of the new 3-GeV accelerator Taiwan Photon Source (TPS) which will be opened to users with limited beam lines in 2016. On the other hand, TLS has 25 beamlines and still serves users very well as being benefited by its mature operation skills and continuous efforts on maintenance and system improvement. Main challenges and corresponding solutions on TLS operation in these recent years t are presented herein, together with the statistics on operation performance.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOY018  
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