Keyword: feedback
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MOBD3 Development of a 9 MHz 15 kW Solid-state CW Amplifier for RHIC impedance, network, cavity, resonance 67
 
  • S.C. Dillon
    Tomco Technologies, Stepney, South Australia, Australia
  
  This paper describes the technical details of the development of a high-power solid-state amplifier for Brookhaven Laboratory. The amplifier must withstand short duration events of 100% full-power reflection, and also must guarantee delivery of continuous power into any load impedance at any angle.  
slides icon Slides MOBD3 [10.800 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOBD3  
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MOPWA001 Instability Thresholds and Tune Shift Estimation for Sirius impedance, emittance, damping, simulation 70
 
  • F.H. de Sá, L. Liu, N. Milas, X.R. Resende
    LNLS, Campinas, Brazil
  
  In this work we present the evaluation of longitudinal and transverse instability thresholds as well as tune shifts for Sirius using time and frequency domain codes that are being developed in-house and take into account various effects on the beam instability, such as bunch by bunch feedback system, quadrupolar impedances from undulator chambers and tune spreads.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA001  
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MOPWA034 Coupled-Bunch Instability Suppression Using RF Phase Modulation at the DELTA Storage Ring damping, synchrotron, storage-ring, electron 179
 
  • M. Sommer, M. Höner, B.D. Isbarn, S. Khan, B. Riemann, T. Weis
    DELTA, Dortmund, Germany
  
  Funding: Work supported by the BMBF under contract no. 05K13PEB
The upcoming upgrade of BESSY II, called BESSY-VSR*, involves the utilization of superconducting multicell RF-resonators with high accelerating gradients to provide short and long bunches in an electron storage ring simultaneously. Even under the assumption of strongest available damping of beam induced modes, the residual impedances of the cavities may cause collective multibunch instabilities at the frontier of stability available from current bunch-by-bunch feedback systems. At the DELTA electron storage ring, a phase modulation of the driving RF is used to suppress coupled-bunch instabilities and to increase the lifetime. The time dependent frequency variation in the order of the synchrotron frequency gives rise to additional damping of the bunch oscillators by decoherence and Landau damping. The behaviour and the additional damping of the bunch oscillators is investigated by the existing bunch-by-bunch feedback system e.g. the increase of the overall damping might support the capability of feedback systems under extreme operating conditions of BESSY-VSR.
* G. Wüstefeld et al., Proc. of IPAC'11, San Sebastián, THPC014 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA034  
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MOPJE072 Simulations and Measurements of Longitudinal Coupled-bunch Instabilities in the CERN PS cavity, synchrotron, luminosity, impedance 479
 
  • L. Ventura, H. Damerau, M. Migliorati, G. Sterbini
    CERN, Geneva, Switzerland
  • M. Migliorati, L. Ventura
    INFN-Roma1, Rome, Italy
  • M. Migliorati
    University of Rome La Sapienza, Rome, Italy
  • L. Ventura
    University of Rome "La Sapienza", Rome, Italy
  
  Among various and challenging objectives of the LHC Injectors Upgrade project (LIU), one aim is to double the beam intensity of the CERN Proton Synchrotron (PS) in order to achieve the integrated luminosity target of the High-Luminosity LHC project (HL-LHC). A known limitation to reach the required high intensity is caused by the longitudinal coupled-bunch oscillations developing above the transition energy. The unwanted oscillations induce large bunch-to-bunch intensity variations not compatible with the specifications of the future LHC-type beams. A wide-band longitudinal damper has been installed in the PS to suppress these instabilities and is going to be commissioned. A measurement campaign of coupled-bunch oscillations has been launched to substantiate the extrapolations and predictions for the future High Luminosity LHC beam with the final aim to determine the maximum intensity that could be provided to the LHC. In parallel a Simulink© model of the PS is going to be implemented to predict the machine behavior in the parameter space of LIU and to be used during the beam commissioning and optimization of the feedback system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE072  
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MOPMA006 Modeling RF Feedback in Elegant for Bunch-Lengthening Studies for the Advanced Photon Source Upgrade cavity, injection, storage-ring, impedance 540
 
  • T.G. Berenc, M. Borland
    ANL, Argonne, Ilinois, USA
  
  Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The proposed Advanced Photon Source (APS) multi-bend achromat (MBA) lattice includes a passive bunch-lengthening cavity to alleviate lifetime and emittance concerns. Feedback in the main radio-frequency (rf) system affects the overall impedance presented to the beam in this double rf system. To aid beam stability studies, a realistic model of rf feedback has been developed and implemented in elegant and Pelegant. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA006  
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MOPMA007 Tracking Studies of a Higher-Harmonic Bunch-Lengthening Cavity for the Advanced Photon Source Upgrade simulation, cavity, timing, impedance 543
 
  • M. Borland, T.G. Berenc, R.R. Lindberg, A. Xiao
    ANL, Argonne, Ilinois, USA
  
  Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The Advanced Photon Source (APS) multi-bend achromat (MBA) lattice will require a bunch-lengthening cavity to decrease the effects of Touschek scattering on the beam lifetime and of intrabeam scattering on the beam emittance. Using ELEGANT, we've performed tracking studies of a passive, i.e. beam-driven, fourth-harmonic cavity in the MBA lattice, including the predicted longitudinal impedance of the ring. The studies include an exploration of the required detuning and loaded Q of the main rf cavities and the harmonic cavity in order to stabilize the beam and achieve significant lengthening. We also studied the effects of bunch population variation and missing bunches. The computed bunch profiles are used for computation of the Touschek lifetime, verifying the beneficial effects in detail. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA007  
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MOPHA001 Transverse Bunch by Bunch Feedback Operations at the Australian Synchrotron Light Source operation, resonance, storage-ring, synchrotron 769
 
  • R.T. Dowd, M.P. Atkinson, M.J. Boland, G. LeBlanc, Y.E. Tan, K. Zingre
    SLSA, Clayton, Australia
  
  The Australian Synchrotron light source has recently put in operation its transverse bunch-by-bunch feedback system during user beam mode. Getting to the stage of stable operation has been a long road and this paper will outline the many difficulties that were encountered. Chief among these are the apparent strong, high frequency, vertical resonances that appear when the storage ring's three in-vacuum undulators are closed to specific gaps. The behaviour of these resonances and their effects on achieving stable feedback operation will be explored in detail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA001  
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MOPHA003 Status of ATF2 IP-BPM Project cavity, electronics, operation, status 777
 
  • O.R. Blanco-García, P. Bambade, F. Bogard, P. Cornebise, S. Wallon
    LAL, Orsay, France
  • D.R. Bett, N. Blaskovic Kraljevic, T. Bromwich
    JAI, Oxford, United Kingdom
  • P. Burrows, G.B. Christian, C. Perry
    Oxford University, Physics Department, Oxford, Oxon, United Kingdom
  • Y. Honda, K. Kubo, S. Kuroda, T. Naito, T. Okugi, T.T. Tauchi, N. Terunuma
    KEK, Ibaraki, Japan
  • S.W. Jang, E.-S. Kim
    KNU, Deagu, Republic of Korea
  
  The efforts during the second half of 2014 towards nano-metric beam position measurement and stabilization at the Interaction Point (IP) section of the Accelerator Test Facility (ATF) at KEK are presented. Recent improvements to the beam position monitor (BPM) data analysis and processing electronics, as well as the installation of a new set of C-Band BPMs, are reviewed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA003  
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MOPHA006 A Slow RF-Laser Feedback for PHIL Photoinjector laser, gun, electron, controls 784
 
  • N. ElKamchi, V. Chaumat, V. Soskov
    LAL, Orsay, France
  
  PHIL is an electron beam accelerator at LAL. It produces low energy (E<5 MeV) and high current (1 nC/bunch) electrons bunch at a repetition frequency of 5Hz. The stability of the beam charge at PHIL is a key issue for the succeful operation of the physic experiences that use the machine. At PHIL, the beam charge is quite stable, but we often note a slow charge drift on long duration experiences. Two ICTs, and a back-end electronics are used to monitor the stability of the beam charge, with an accuracy of about 1pC. Several types of jitter can impact the stability of the beam charge. The fluctuations of the RF power or the RF-laser relative phase drift could have significant influence, due to temperature variations that produce cables dilataion, and electronic components overheating. To correct the phase drift, we describe a method based on a slow analog-digital feedback loop between the RF wave in the gun (3 GHz) and the synchronisation signal of the laser (75MHz). It allows to maintain the jitter between the laser pulse and the RF wave stable at a very low value. As a result, the electron beam charge is maintained at a stable level, to meet the requirements of the users.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA006  
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MOPHA010 RF Feedback and Detuning Studies for the BESSY Variable Pulse Length Storage Ring Higher Harmonic SC Cavities cavity, beam-loading, synchrotron, operation 798
 
  • A. Neumann, P. Echevarria, P. Goslawski, M. Ries, M. Ruprecht, A.V. Vélez, G. Wüstefeld
    HZB, Berlin, Germany
  
  For the feasibility of the BESSY VSR upgrade project of BESSY II two higher harmonic systems at a factor of 3 and 3.5 of the ring's RF fundamental of 500 MHz will be installed in the ring. Operating in continuous wave at high average accelerating field of 20 MV/m and phased at zero-crossing, the superconducting cavities have to be detuned within tight margins to ensure stable operation and low power consumption at a loaded Q of 5·107. The field variation of the cavities is mainly driven by the repetitive transient beam-loading of the envisaged complex bunch fill pattern in the ring. Within this work combined LLRF-cavity and longitudinal beam dynamics simulation will demonstrate the limits for stable operation, especially the coupling between synchrotron oscillation and RF feedback settings. Further impact by beam current decay and top-up injection shots are being simulated.
* G. Wüstefeld et al., IPAC 11, San Sebastiàn, Spain, p. 2936. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA010  
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MOPHA021 Bunch-by-Bunch Longitudinal RF Feedback for Beam Stabilization at FAIR LLRF, controls, cavity, synchrotron 820
 
  • K. Groß, H. Klingbeil
    TEMF, TU Darmstadt, Darmstadt, Germany
  • U. Hartel, H. Klingbeil, U. Laier, D.E.M. Lens, K.-P. Ningel, S. Schäfer, B. Zipfel
    GSI, Darmstadt, Germany
  
  Funding: Work supported by the German Federal Ministry of Education and Research (BMBF) under the project 05P12RDRBF.
To damp undesired longitudinal oscillations of bunched beams, the main synchrotron SIS100 of FAIR (Facility for Antiproton and Ion Research) will be equipped with a bunch-by-bunch feedback system. This helps to stabilize the beam, to keep longitudinal emittance blow-up low and to minimize beam losses. The proposed LLRF (low level radio frequency) topology of the closed loop feedback system is described. In some aspects, it is similar to the beam phase control system* developed at GSI Helmholtzzentrum für Schwerionenforschung GmbH. The differences and challenges are pointed out, which are mainly the bunch-by-bunch signal processing followed by the generation of a correction voltage in dedicated feedback cavities. The adapted topology was verified at SIS18 during beam time in 2014 using LLRF prototype subsystems and the two existing ferrite-loaded acceleration cavities. The experimental setup to damp coherent longitudinal dipole oscillations is presented and evaluated with focus on the realized modifications, including ongoing and pending investigations. Finally, the current status of the longitudinal feedback system for FAIR is summarized.
* Klingbeil et al., IEEE Trans. Nuc. Sci., Vol. 54, No. 6, 2007. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA021  
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MOPHA028 Operation of Normal Conducting RF Guns with MicroTCA.4 gun, LLRF, cavity, operation 841
 
  • M. Hoffmann, V. Ayvazyan, J. Branlard, L. Butkowski, M.K. Grecki, U. Mavrič, M. Omet, S. Pfeiffer, H. Schlarb, Ch. Schmidt
    DESY, Hamburg, Germany
  • W. Fornal, R. Rybaniec
    Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
  • A. Piotrowski
    FastLogic Sp. z o.o., Łódź, Poland
  
  During the last half year, the MicroTCA.4 based single cavity LLRF control system was installed and commissioned at several normal conducting facilities at DESY (FLASH RF gun, REGAE, PITZ RF gun, and XFEL RF gun). First tests during the last year show promising results in optimizing the system for high speed digital LLRF feedbacks, i.e. reducing system latency, increasing the internal controller processing speed, testing new control schemes, and optimizing controller parameters. In this contribution we will present results and gained experience from the commissioning phase and the first time period of real operation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA028  
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MOPHA044 Testing a Digital Beam Position Stabilization for the P2-experiment at MESA experiment, FPGA, controls, electron 888
 
  • M. Dehn, K. Aulenbacher, J. Diefenbach, F. Fichtner, R. Herbertz, W. Klag
    IKP, Mainz, Germany
  
  Funding: Work supported by the German Federal Ministry of Education and Research (BMBF) and German Research Foundation (DFG) under the Collaborative Research Center 1044 and the Cluster of Excellence "PRISMA"
The Mainz Energy recovering Superconducting Accelerator (MESA) will be built at the institute for nuclear physics at Mainz University. Besides the multi-turn energy recovery mode an external beam mode is foreseen to provide 155 MeV electrons of 85% polarization at 150 μA for parity violating experiments. To achieve the required stability of the main beam parameters a dedicated digital position stabilization is currently developed and tested at the Mainz Microtron (MAMI). 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA044  
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MOPHA045 Developments and Performance of the LLRF System of the S-Band FERMI Linac LLRF, klystron, cavity, controls 891
 
  • A. Fabris, F. Gelmetti, M. Milloch, M. Predonzani
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  
  The requirements on beam quality on the FERMI Free Electron Laser (FEL) linac impose challenging specifications on the stability of the RF fields that can only be met by using high reliable and high performance state of the art LLRF systems. The system installed in FERMI has met these requirements and is routinely operational for the machine on a 24/7 basis. The completion of the deployment of the LLRF units in 2015 increases the capabilities of the system, adding further measurement channels and monitoring, and allowing new functionalities. This paper provides an overview of the results achieved with the LLRF system of FERMI and an outlook of the further developments that are being implemented or planned.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA045  
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MOPHA054 Interaction Point Orbit Feedback System at SuperKEKB luminosity, quadrupole, simulation, vacuum 921
 
  • Y. Funakoshi, H. Fukuma, T. Kawamoto, M. Masuzawa, T. Oki, S. Uehara, H. Yamaoka
    KEK, Ibaraki, Japan
  • S.D. Anderson, S.M. Gierman, M. Kosovsky, J.T. Seeman, C.M. Spencer, M.K. Sullivan, O. Turgut, U. Wienands
    SLAC, Menlo Park, California, USA
  • P. Bambade, D. El Khechen, D. Jehanno, V. Kubytskyi, C. Rimbault
    LAL, Orsay, France
  
  In order to maintain an optimum beam collision condition in a double ring collider such as SuperKEKB it is essential to have an orbit feedback system at the interaction point (IP). We have designed such a system based on experiences at KEKB and PEP-II. For the vertical offset and crossing angle, we will rely on the system based on the beam orbit measurement similar to that used at KEKB. For the horizontal offset, however, we will utilize the dithering system which was successfully used at PEP-II, because the horizontal beam-beam kick is very weak with the "nano-beam scheme". Some hardware devices have been already fabricated and others are in preparation. The present status of the development is reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA054  
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MOPTY001 Development of Wideband BPM for Precise Measurement of Internal Bunch Motion impedance, coupling, synchrotron, network 937
 
  • K.G. Nakamura
    Kyoto University, Kyoto, Japan
  • Y.H. Chin, T. Koseki, T. Obina, M. Okada, M. Tobiyama, T. Toyama
    KEK, Ibaraki, Japan
  • Y. Shobuda
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  
  Funding: This work was supported by MEXT KAKENHI Grant Number 25105002, Grant-in-Aid for Scientific Research on Innovative Areas titled “ Unification and　Development of the Neutrino Science Frontier”
To suppress intra-bunch oscillations and to reduce particle losses, the intra-bunch feedback (IBFB) system has been developed in 2014 for the J-PARC Main Ring (MR). A new BPM was also installed to the MR for the IBFB system. This BPM has a sufficient frequency response and position sensitivity(up to 1.5GHz within 15% fluctuation ). However, a better performance may be needed in future for more precise analysis of internal motions (e.g. due to an electron cloud). We report the development of the BPM and precise measurement results of the BPM characteristics. We also report simulation studies of the digital equalizer which helps to reconstructs the beam shape from beam signals. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY001  
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MOPTY038 NSLS-II Digital RF Controller Logic and Applications cavity, EPICS, FPGA, controls 1010
 
  • B. Holub, F. Gao, J.G. Kulpin, C. Marques, J. Oliva, J. Rose, N.A. Towne
    BNL, Upton, New York, USA
  
  The National Synchrotron Light Source II accelerator consists of the Storage Ring, the Booster Ring, and Linac along with their associated cavities. NSLS II is committed to the use of digital RF controllers for controlling these cavities. Given the number, types and variety of functions of these cavities, we sought to limit the logic development effort by reuse of parameterized code on one hardware platform. Currently we have fielded six controllers in the NSLS II system. There are two controllers each in both the Storage ring and Booster. The first controller in each is used to control the cavity field and the second controller used for diagnostics. In the Linac a controller is provided which modulates the eGUN grid to generate the bunches. Lastly, in the Master Oscillator Distribution System a controller is used to make phase corrections to the outgoing master oscillator clock signal to account for thermal phase drifts along the distribution path.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY038  
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MOPTY071 FPGA Based Global Orbit Feedback in the Taiwan Light Source controls, FPGA, interface, brilliance 1100
 
  • C.H. Kuo, Y.-S. Cheng, P.C. Chiu, K.T. Hsu, K.H. Hu, D. Lee
    NSRRC, Hsinchu, Taiwan
  
  The global orbit feedback for the 1.5 GeV electron storage ring of TLS has been operated more than ten years. This system uses general processors to control feedback loop with 1 kHz rate. It is very important for various operation of storage ring now, but some hardware components could have been out of stock in the future. As a prototype, a FPGA based fast global orbit feedback at a 10 kHz data acquisition rate has been developed. A micro-TCA liked platform with FPGA board is used to implement control algorithm and acquire BPM data from Libera Brillance. The correction algorithm is written in VHDL and connected to power supply with AURORA digital links. The system architecture will be discussed in this report.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY071  
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MOPTY083 Progress towards Electron-beam Feedback at the Nanometre Level at the Accelerator Test Facility (ATF2) at KEK cavity, kicker, extraction, electron 1133
 
  • P. Burrows, D.R. Bett, N. Blaskovic Kraljevic, T. Bromwich, G.B. Christian, M.R. Davis, C. Perry
    JAI, Oxford, United Kingdom
  • D.R. Bett
    CERN, Geneva, Switzerland
  
  Ultra-low latency beam-based digital feedbacks have been developed by the Feedback On Nanosecond Timescales (FONT) Group and tested at the Accelerator Test Facility (ATF2) at KEK in a programme aimed at beam stabilisation at the nanometre level at the ATF2 final focus. Three prototypes were tested: 1) A feedback system based on high-resolution stripline BPMs was used to stabilise the beam orbit in the beamline region c. 50m upstream of the final focus. 2) Information from this system was used in a feed-forward mode to stabilise the beam locally at the final focus. 3) A final-focus local feedback system utilising cavity BPMs was deployed. In all three cases the degree of beam stabilisation was observed in high-precision cavity BPMs at the ATF2 interaction point. Latest results are reported on stabilising the beam position to below 100 nanometres.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY083  
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MOPWI011 Beam Stability R&D for the APS MBA Upgrade diagnostics, insertion, controls, insertion-device 1167
 
  • N. Sereno, N.D. Arnold, H. Bui, J. Carwardine, G. Decker, L. Emery, R.I. Farnsworth, R.T. Keane, F. Lenkszus, R.M. Lill, R. Lipa, S. Veseli, S. Xu, B.X. Yang
    ANL, Argonne, Ilinois, USA
  
  Funding: Results shown in this report result from work performed at Argonne National Laboratory operated by UChicago Argonne, LLC, for the U.S. Department of Energy under contract DE-AC02-06CH11357.
Beam diagnostics required for the APS MBA are driven by ambitious beam stability requirements. The major AC stability challenge is to correct rms beam motion to 10% the rms beam size at the insertion device source points from 0.01 to 1000 Hz. The vertical plane represents the biggest challenge for AC stability which is required to be 400 nm rms for a 4 micron vertical beam size. Long term drift over a period of 7 days is required to be 1 micron or less. Major diagnostics R&D components are improved rf beam position processing using commercially available fpga based bpm processors, new XRay beam position monitors sensitive only to hard X-rays, mechanical motion sensing and remediation to detect and correct long term drift and a new feedback system featuring a tenfold increase in sampling rate and a several-fold increase in the number of fast correctors and bpms. Feedback system development represents a major effort and we are pursuing development of a novel algorithm that integrates orbit correction for both slow and fast correctors down to DC simultaneously. Finally a new data acquisition system (DAQ) is being developed to acquire streaming data from all diagnostics. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWI011  
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MOPWI034 Adaptive Accelerator Tuning controls, DTL, hardware, simulation 1237
 
  • A. Scheinker
    LANL, Los Alamos, New Mexico, USA
  
  We start with an overview of advanced adaptive control schemes in use throughout the accelerator community. We then present a recently developed, novel, model-independent feedback controller*, which is robust to measurement noise, and able to tune an arbitrary number of coupled parameters simultaneously based only on a user-defined cost function. We discuss the possibility of combining virtual beam measurements from simulations with actual diagnostic signals from the accelerator into a single cost function, which takes into account both unknown machine variations and estimates of physically inaccessible beam characteristics. We present recent in-hardware experimental results obtained at the Los Alamos Neutron Science Center** and at the Facility for Advanced Accelerator Tests (FACET)***, demonstrating the scheme’s ability to simultaneously tune many parameters and its robustness to noise and system time-variation.
* A. Scheinker et al., PRSTAB, 16, 102803, 2013.
** A. Scheinker et al., NIMA, 756, pp. 30-38, 2014.
*** A. Scheinker and S. Gessner, Conference on Decision and Control, 2014. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWI034  
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MOPWI037 Upgrade and Operation of the Demonstration 4 GS/Sec. Intra-Bunch Instability Control System for the SPS kicker, controls, pick-up, FPGA 1246
 
  • J.E. Dusatko, J.D. Fox, C.H. Rivetta, O. Turgut
    SLAC, Menlo Park, 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).
We present the expanded system implementation and operational experience details for the “Demo” technology platform commissioned at the SPS in January 2015. The system has been expanded during the LS1 shutdown with added features. The upgraded system has enhanced performance and more robust synchronization to the beam and accelerator timing system. Central to the new features are 1 GHz bandwidth kickers and RF amplifiers (including associated equalizers) which allow excitation and control of higher modes within the 2 ns bunch. We highlight the expanded features, and present their details. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWI037  
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MOPWI041 Identification of Intra-Bunch Transverse Dynamics for Model Based Wideband Feedback Control at CERN Super Proton Synchrotron controls, simulation, proton, synchrotron 1249
 
  • O. Turgut, J.E. Dusatko, J.D. Fox, C.H. Rivetta
    SLAC, Menlo Park, 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).
Multi-input multi-output (MIMO) feedback design techniques can be helpful to stabilize intra-bunch transverse instabilities induced by electron-clouds or transverse mode couplings at the CERN Super Proton Synchrotron (SPS). These MIMO techniques require a reduced order model of intra-bunch dynamics. We estimate a linear reduced order MIMO models for transverse intra-bunch dynamics and use these models to design model based MIMO feedback controllers. The effort is motivated by the plans to increase currents in the SPS as part of the HL-LHC upgrade. Parameters of the reduced order models are estimated based on driven beam SPS measurements. We study different types of controllers. We test the model based designs using macro particle simulation codes (CMAD and HEADTAIL) and compare its performance with FIR filters tested during beam measurements of the feedback system in SPS machine development (MD) studies. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWI041  
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TUXC2 Engineering Challenges of Future Light Sources storage-ring, vacuum, emittance, synchrotron 1308
 
  • R.T. Neuenschwander, L. Liu, S.R. Marques, A.R.D. Rodrigues, R.M. Seraphim
    LNLS, Campinas, Brazil
  
  We review some of the present engineering challenges associated with the design and construction of ultra-low emittance storage rings, the 4th generation storage rings (4GSR). The field is experiencing a growing interest since MAX-IV, followed by Sirius, started to build storage rings based on multi-bend-achromat (MBA) lattices. It was the recent progress in accelerator technology that allowed these facilities to base their designs on this kind of lattice. Although the challenges are starting to be overcome, many issues are still open and a lot of R&D is required until the 4GSR achieve optimal performance.  
slides icon Slides TUXC2 [7.022 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUXC2  
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TUAC2 Wideband Vertical Intra-Bunch Feedback At The SPS - 2015 Results And Path Forward controls, kicker, simulation, optics 1353
 
  • C.H. Rivetta, J.E. Dusatko, J.D. Fox, O. Turgut
    SLAC, Menlo Park, California, USA
  • 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)
We present experimental measurements taken from CERN SPS machine development studies with a wideband intra-bunch feedback channel prototype. The demonstration system is a digital processing system with recently installed wideband kicker and amplifier components. This new hardware extends the bandwidth up to 1GHz and allows driving and controlling multiple vertical transverse modes in the bunch. The studies are focused on both driving the bunch with spectrally controlled signals to identify a reduced model of the bunch dynamics and testing model-based feedback controllers to stabilize the bunch dynamics. The measurements are structured to validate reduced MIMO models and macro-particle simulation codes, including the dynamics and limits of the feedback channel. Noise effects and uncertainties in the model are evaluated via SPS measurements to quantify the limits of control techniques applied to stabilize the intrabunch dynamics. The design of controllers for Q26 and Q20 optics are illustrated and future control developments are described. 		 
slides icon Slides TUAC2 [30.936 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUAC2  
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TUPJE044 Local Orbit Response Matrix Measurement at SLS quadrupole, optics, storage-ring, focusing 1713
 
  • M. Aiba, M. Böge
    PSI, Villigen PSI, Switzerland
  
  The experimental determination of linear optics is essential to achieve a high performance ring accelerator. One of the methods, linear optics from closed orbits (LOCO), is widely employed to correct linear optics. Due to the ring nature, a quadrupole error at a location of the ring affects the entire orbit response measurement data. The orbit response, however, can be localised to a certain range of the ring when an orbit feedback (or correction) is applied to the rest of the ring. The quadrupole errors located in the range, where the feedback is acting, then have no impact, and the ring optics can be locally examined. An application of this technique to Swiss light source is discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE044  
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TUPMA052 NSLS-II Radio Frequency Systems cavity, storage-ring, operation, booster 1947
 
  • J. Rose, F. Gao, B. Holub, J.G. Kulpin, C. Marques
    BNL, Upton, Long Island, New York, USA
  • A. Goel
    ANL, Argonne, Ilinois, USA
  • M. Yeddulla
    Varian Medical Systems, Inc., Palo Alto, California, USA
  
  Funding: Work supported by DOE contract DE-SC0012704
The National Synchrotron Light Source II is a 3 GeV X-ray user facility commissioned in 2014. The NSLS-II RF system consists of the master oscillator, digital low level RF controllers, linac, booster and storage ring RF sub-systems, as well as a supporting cryogenic system. Here we will report on RF commissioning and early operation experience of the system. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPMA052  
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TUPWI047 Target and Orbit Feedback Simulations of a muSR Beamline at BNL target, solenoid, proton, kicker 2353
 
  • W. Fischer, M. Blaskiewicz, P.H. Pile
    BNL, Upton, Long Island, New York, USA
  • W.W. MacKay
    Weirich Consulting Services, Inc., Huntersville, North Carolina, USA
  
  Funding: Work supported by U.S. DOE under contract No DE-AC02-98CH10886 with the U.S. Department of Energy.
Well-polarized positive surface muons are a tool to measure the magnetic properties of materials since the precession rate of the spin can be determined from the observation of the positron directions when the muons decay. The use of the AGS complex at BNL has been explored for a muSR facility previously. Here we report simulations of a beamline with a target inside a solenoid, and of an orbit feedback system with single muon beam positioning monitors based on technology available today. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWI047  
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WEXB2 Measurement and Analysis of Electron Cloud Induced Emittance Growth at CesrTA electron, simulation, emittance, positron 2390
 
  • K.G. Sonnad, L.Y. Bartnik, M.G. Billing, G. Dugan, M.J. Forster
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • J.W. Flanagan, K. Ohmi
    KEK, Ibaraki, Japan
  • R. Holtzapple, K.E. McArdle, M.I. Miller
    CalPoly, San Luis Obispo, California, USA
  • L. Pentecost
    Colgate University, Hamilton, New York, USA
  • M.T.F. Pivi
    EBG MedAustron, Wr. Neustadt, Austria
  • S. Tucker
    Cal Poly, San Luis Obispo, California, USA
  
  CesrTA is a test accelerator facility at Cornell University that has been configured to study physics associated with electron and positron damping rings. Electron cloud effects is a concern for positron beams for such damping rings. The presentation will give an overview of recent measurements and simulation results for CesrTA. The measurement conditions were set up in order to study single bunch phenomena by observing a "Witness bunch" behind a train of positron bunches. The beam size and the turn by turn spectra were obeserved for the witness bunch under different conditions. Simulations were performed under similar conditions using the program CMAD.  
slides icon Slides WEXB2 [2.263 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEXB2  
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WEPHA041 ALGORITHM AND CIRCUIT TO IMPROVE ZERO-CROSSING STABILITY OF BIPOLAR TPS TRIM COIL POWER SUPPLY controls, simulation, FPGA, interface 3206
 
  • B.S. Wang, Y.-C. Chien, P.C. Chiu, K.T. Hsu, C.Y. Liu, K.-B. Liu, Y.S. Wong, C.Y. Wu
    NSRRC, Hsinchu, Taiwan
  
  In TPS (Taiwan Photon Source) project, 58 home-built small form factor bipolar power supplies are used to fine-tune the trim coil of booster ring bending dipole magnets. With the preliminary analog PI control loop design version, current output will tend to behave with poor linearity around zero current. By employing DSP chip, a full digital PI control loop design together with optimal MOSFT switching algorithm and 13bits PWM output capability is capable of improving the output current performance around zero current. Before the final realization, MATLAB SIMULINK is utilized to find out the optimal MOSFT switching algorithm, and then physical circuit is implemented and tested. The result and design will be demonstrated in this paper to show significant improvement around zero current.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA041  
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WEPTY004 Mathematical Modeling and Analysis of a Wide Bandwidth Bipolar Power Supply for the Fast Correctors in the APS Upgrade Controller power-supply, controls, simulation, operation 3264
 
  • B. Song, J. Wang
    ANL, Argonne, Ilinois, USA
  
  Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The APS Upgrade requires a fast bipolar power supply for the fast correction magnets. The performance requirement of the power supply includes a -3dB at 10 kHz small-signal bandwidth for the output current. This requirement presents a technical challenge to the design of the power circuit and the power supply regulator because the magnet load may have a significant inductance and make it difficult to achieve a high bandwidth for the current. In order to meet the requirement, different circuit topologies and regulators are being investigated. One of the candidate designs combines a standard H-bridge pulse-width modulation (PWM) circuit and a linear power amplifier to provide a ±15A DC current and an AC component up to 1% of the full scale with the required bandwidth. An appropriate feedback control loop and a current regulator are being designed. The mathematical modeling and simulation of the power circuit and the control loop are being conducted to prove the concept of the design. This paper presents the design of the circuit, mathematical modeling, and the simulation results. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY004  
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WEPTY020 Design of a Marx-Topology Modulator for FNAL Linac linac, cavity, proton, flattop 3306
 
  • T.A. Butler, F.G. Garcia, M.R. Kufer, H. Pfeffer, D. Wolff
    Fermilab, Batavia, Illinois, USA
  
  The Fermilab Proton Improvement Plan (PIP) was formed in 2011 to address important and necessary upgrades to the Proton Source machines (Injector line, Linac and Booster). The goal is to increase the proton flux by doubling the Booster beam cycle rate while maintaining the same intensity per cycle, the same uptime, and the same residual activation on the accelerating structures. For Linac, the main focus within PIP is to address reliability. One of the main tasks is to replace the present hard-tube modulator used on the main 200MHz RF system. Plans to replace this high power system with a Marx-topology modulator, capable of providing the required waveform shaping to stable the accelerating gradient and compensate for beam loading, will be presented along with development data from the prototype unit.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY020  
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WEPTY036 Progress at FNAL in the Field of the Active Resonance Control for Narrow Bandwidth SRF Cavities. cavity, resonance, operation, controls 3355
 
  • W. Schappert, J.P. Holzbauer, Y.M. Pischalnikov
    Fermilab, Batavia, Illinois, USA
  
  Funding: Fermi Research Alliance, LLC under Contract N. DE-AC02-07CH11359 with U.S. Department of Energy.
Recent efforts at FNAL to actively compensate microphonics in narrow bandwidth cavities are discussed. Feed-forward compensation of Lorentz force detuning in combination with feedback of the forward/probe phase difference to a piezo actuator successfully stabilized the resonance of a 325 MHz spoke resonator to within 11 mHz of the frequency of the open-loop CW RF drive over a two hour interval. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY036  
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WEPWI006 Dither Coils for the SuperKEKB Fast Collision Feedback System vacuum, collider, coupling, multipole 3500
 
  • U. Wienands, S.D. Anderson, S.M. Gierman, M. Kosovsky, C.M. Spencer, M.K. Sullivan
    SLAC, Menlo Park, California, USA
  • Y. Funakoshi, M. Masuzawa, T. Oki
    KEK, Ibaraki, Japan
  
  Funding: Work supported in part by US DOE and in part by the US-Japan collaboration agreement.
The collision feedback system for the SuperKEKB electron-positron collider at KEK will employ a dither feedback with a roughly 100 Hz excitation frequency to generate a signal proportional to the offset of the two beams. The excitation will be provided by a local bump across the interaction point (IP) that is generated by a set of eight air-core solid-wire magnet coil assemblies, each of which provides a horizontal and/or vertical deflection of the beam, to be installed around the vacuum system of the SuperKEKB Low Energy Ring. The design of the coils was challenging as large antechambers had to be accommodated and a 0.1% relative field uniformity across a good-field region of ±1 cm was aimed for, while keeping reasonable dimensions of the coils. This led to non-symmetric, non-flat designs of the coils. The paper describes the magnetic design and the method used to calculate the magnetic field of the coils, the mechanical design and the field measurement results. Tracking in the lattice model has indicated acceptable performance. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI006  
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WEPWI045 Status of Superconducting Traveling Wave Cavity for High Gradient Linac cavity, accelerating-gradient, vacuum, cryogenics 3591
 
  • R.A. Kostin, P.V. Avrakhov, A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • T.N. Khabiboulline, Y.M. Pischalnikov, N. Solyak, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  
  The use of a travelling wave (TW) accelerating structure with a small phase advance per cell instead of standing wave may provide a significant increase of accelerating gradient in a superconducting linear accelerator. The TW section achieves an accelerating gradient 1.2-1.4 times larger than TESLA-shaped standing wave cavities for the same surface electric and magnetic fields. The final stage of a 3-cell superconducting travelling wave cavity development is presented. This cavity will be tested in travelling wave regime at cryogenic temperature.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI045  
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THYC1 Comparison of Beam Diagnostics for 3rd and 4th Generation Ring-based Light Sources photon, diagnostics, emittance, electronics 3657
 
  • H. Maesaka
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
  
  This talk will present the challenges and progress required in beam instrumentation for next generation storage-ring light sources. These light sources aim at small natural emittance of approximately 100 pm rad in order to achieve much higher brightness than the present 3rd generation light sources. This small emittance is realized by a multi-bend lattice, which has a small dynamic aperture of only several mm, a small beam size of approximately 10 microns, etc. Therefore, the beam orbit must be precisely measured by beam position monitors (BPM) for the orbit correction and the beam size should be monitored with less than 10-micron resolution in order to estimate the beam emittance. A bunch-by-bunch feedback system is also required for the suppression of various instabilities coming from narrow beam chamber. In addition, since the stable tune region is small, a real-time tune monitor is demanded for the tune correction. We introduce leading-edge instrumentation techniques to overcome these difficulties, comparing with of 3rd generation light sources.  
slides icon Slides THYC1 [3.690 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THYC1  
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