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MOPC027 A Fast Switching Mirror Chamber for FLASH laser, radiation, electron, controls 124
 
  • S. Pauliuk, U. Gensch, R. Heller, M. Sachwitz, H. Thom, D. Thürmann
    DESY Zeuthen, Zeuthen
  • U. Hahn, S. Karstensen, H. Schulte-Schrepping, K. I. Tiedtke
    DESY, Hamburg
  Switching mirrors are used to provide several beamlines with FEL or synchrotron radiation from one source. Since most users do not need the nominal pulse density, this is a method to supply many experimental groups. So far, the switching process has a duration of several minutes. A study at DESY Zeuthen analyzes the possibility and accuracy of permanent switching, e.g. at half the FEL's pulse frequency of 1 to 10 Hz. A prototype satisfying highest demands on repetition accuracy of the position (below 1 μm) and yawing (about 1 arcsec) is being tested. In the course of the work many technical concepts from industry like PLC or Position-Velocity Streaming found their way into beamline technology, allowing fast proceedings in development.  
 
MOPC126 Beam Acceleration with Full-digital LLRF Control System in the J-PARC RCS injection, controls, acceleration, synchrotron 364
 
  • F. Tamura, K. Haga, K. Hasegawa, M. Nomura, A. Schnase, M. Yamamoto
    JAEA/J-PARC, Tokai-mura
  • S. Anami, E. Ezura, K. Hara, C. Ohmori, A. Takagi, M. Toda, M. Yoshii
    KEK, Ibaraki
  In the J-PARC RCS (Rapid Cycling Synchrotron) we employ a full-digital LLRF control system to accelerate an ultra-high intensity proton beam. The key feature is the multi-harmonic RF signal generation by using direct digital synthesis (DDS) technology. By employing a full-digital system, highly accurate, stable and reproductive RF voltages are generated in the wide-band RF cavities loaded by magnetic alloy (MA) cores. The beam commissioning of the J-PARC RCS has been started in October 2007. The accelerators, the linac and the RCS, show good stability. The beam orbit and the longitudinal beam shape and phase are reproductive from cycle to cycle especially thanks to the stability of the linac energy, the RCS bending field and the frequency and voltage of the RCS RF. This reproductivity makes the beam commissioning efficient. We present the examples of the orbit signals and the longitudinal current signals. Also, we discuss the longitudinal beam control performance and future plans.  
 
MOPP027 Placet Based Start-to-end Simulations of the ILC with Intra-train Fast Feedback System luminosity, linac, simulation, emittance 604
 
  • J. Resta-López, P. Burrows, A. F. Hartin
    JAI, Oxford
  • A. Latina, D. Schulte
    CERN, Geneva
  Integrated simulations are important to assess the reliability of the luminosity performance of the future linear colliders. In this paper we present multi-bunch tracking simulation results for the International Linear Collider (ILC) from the start of the LINAC to the interaction point. The tracking along the LINAC and the beam delivery system is done using the code Placet. This code allows us to introduce cavity wakefield effects, element misalignment errors and ground motion. Static beam based alignment of the LINAC are also considered. The luminosity and beam-beam parameters are calculated using the code Guinea-Pig. In the framework of the Feedback On Nano-second Timescales (FONT) project, we describe and simulate an updated fast intra-train feedback system in order to correct for luminosity degradation mainly due to high frequency ground motion.  
 
MOPP029 The First Measurement of Low-loss 9-cell Cavity in a Cryomodule at STF klystron, superconducting-RF, coupling 610
 
  • T. Saeki, M. Akemoto, S. Fukuda, F. Furuta, K. Hara, Y. Higashi, T. Higo, K. Hosoyama, H. Inoue, A. Kabe, H. Katagiri, S. Kazakov, Y. Kojima, H. Matsumoto, T. Matsumoto, S. Michizono, T. Miura, Y. Morozumi, H. Nakai, K. Nakanishi, N. Ohuchi, K. Saito, M. Satoh, T. Takenaka, K. Tsuchiya, H. Yamaoka, Y. Yano
    KEK, Ibaraki
  • T. Kanekiyo
    Hitachi Technologies and Services Co., Ltd., Kandatsu, Tsuchiura
  • J. Y. Zhai
    IHEP Beijing, Beijing
  We are constructing Superconducting RF Test Facility (STF) at KEK for the R&D of International Linear Collider (ILC) accelerator. In the beginning of year 2008, we installed one high-gradient Low-Loss (LL) type 9-cell cavity into a cryomodule at STF, where we assembled an input coupler and peripherals with the cavity in a clean room, and the assembled cavity packages were dressed with thermal shields and installed into a cryomodule. At the room-temperature, we performed the processing of capacitive-coupling input-coupler upto the RF power of 250 kW. At the temperature of 4 K, we measured the loaded Q of the cavity and the tuner was tested. At the temperature of 2 K, high-power RF was supplied from a klystron to the cavity and the performance of the cavity packeage was tested. This article presents the results of the first test of the Low-Loss (LL) 9-cell cavity package at 2 K in a cryomodule.  
 
MOPP068 Simulation Study of Fast Ion Instability in the ILC Damping Ring damping, ion, simulation, electron 703
 
  • G. X. Xia, Eckhard. Elsen
    DESY, Hamburg
  The so-called fast ion instability potentially constitutes a performance limitation for the damping ring of the International Linear Collider (ILC). Based on the latest baseline lattice of the ILC damping ring the fast ion instability is simulated using a weak-strong code. Various fill patterns are examined to mitigate the onset of the instability. Feedback mechanisms are explored. The growth time of the fast ion instability is estimated for various vacuum pressures on the basis of the simulated results.  
 
MOPP110 The SNS Resonance Control Cooling System Control Valve Upgrade Performance controls, resonance, linac, monitoring 814
 
  • D. C. Williams, J. P. Schubert, J. Y. Tang
    ORNL, Oak Ridge, Tennessee
  The normal-conducting linac of the Spallation Neutron Source (SNS) uses 10 separate Resonance Control Cooling System (RCCS) water skids to control the resonance of 6 Drift Tube Linac (DTL) and 4 Coupled Cavity Linac (CCL) accelerating structures. The RCCS water skids use 2 control valves; one to regulate the chilled water flow and the other is used to bypass water to a heat exchanger. These valves have hydraulic actuators that provide position and feedback to the control system. Frequency oscillations occur using these hydraulic actuators due to their coarse movement and control of the valves. New air actuator control positioners have been installed on the DTL3 RCCS water skid to give finer control and regulation of DTL3 cavity temperature. This paper shows a comparison of resonance control performance for two valve configurations.  
 
MOPP120 Full Characterization of the Piezo Blade Tuner for Superconducting RF Cavities insertion, controls, cryogenics, superconducting-RF 838
 
  • A. Bosotti, C. Pagani, N. Panzeri, R. Paparella
    INFN/LASA, Segrate (MI)
  • C. Albrecht, K. Jensch, R. Lange, L. Lilje
    DESY, Hamburg
  • J. Knobloch, O. Kugeler, A. Neumann
    BESSY GmbH, Berlin
  Cavity tuners are mechanical devices designed to precisely match the resonant frequency of the superconducting (SC) cavity to the RF frequency synchronous with the beam. The blade tuner is mounted coaxially to the cavity and changes the resonator frequency by varying its length. A high tuning range is desired together with small mechanical hysteresis, to allow easy and reproducible resonator setup operations. High stiffness is also demanded to the tuner system both to ensure mechanical stability and to mitigate the frequency instabilities induced by perturbations. In high gradient SC resonators, the main sources of resonant frequency instability are the Lorentz Force Detuning (LFD) under pulsed mode operation, and the microphonic noise, in continuous wave (CW) with high loaded quality factors. Piezoceramic elements add dynamic tuning capabilities to the system, allowing fast compensation of these instabilities with the help of feed-forward and feedback loops. The piezo blade tuner has been extensively tested both at room temperature and at cold once assembled on a TESLA type cavity in its final configuration. This paper presents the summary of the complete characterization tests.  
 
MOPP124 Commissioning of the 400 MHz LHC RF System klystron, controls, cryogenics, vacuum 847
 
  • E. Ciapala, L. Arnaudon, P. Baudrenghien, O. Brunner, A. Butterworth, T. P.R. Linnecar, P. Maesen, J. C. Molendijk, E. Montesinos, D. Valuch, F. Weierud
    CERN, Geneva
  The installation of the 400 MHz superconducting RF system in LHC is finished and commissioning is under way. The final RF system comprises four cryomodules each with four cavities in the LHC tunnel. Also underground in an adjacent cavern shielded from the main tunnel are the sixteen 300 kW klystron RF power sources with their high voltage bunkers, two Faraday cages containing RF feedback and beam control electronics, and racks containing all the slow controls. The system and the experience gained during commissioning will be described. In particular, results from conditioning the cavities and their movable main power couplers and the setting up of the low level RF feedbacks will be presented.  
 
MOPP132 Progress Towards Development of an L-Band SC Traveling Wave Accelerating Structure with Feedback acceleration, coupling, resonance, linac 871
 
  • A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio
  • P. V. Avrakhov
    LPI, Moscow
  • S. Kazakov
    KEK, Ibaraki
  • N. Solyak, V. P. Yakovlev
    Fermilab, Batavia, Illinois
  We describe an ongoing experimental program and progress towards development of a conceptual design for a superconducting traveling wave accelerating structure for the ILC. The accelerating gradient can be significantly improved by the use of an RF feedback system redirecting the accelerating wave that passed through the superconducting traveling wave accelerator (STWA) section back to the input of the accelerating structure. The conceptual design of the SC traveling wave accelerator has been considered by P. Avrakhov et al. [PAC07, pp.2538], where shape optimization, coupler cell design and tuning issues in the feedback loop were presented. The proposed TW structure design gives an overall 24% increase in gradient over the 1 m long standing wave structure and potentially can reach 46% if a longer structure is employed. Experimental investigation of the TW SC structure considers tests of a single cavity having the same shape as the regular cell of the full-sized STWA structure, and the same ratio of the RF fields. The details of the individual parts, joint configurations along with some developments on forming and welding of the proposed cavity shapes are discussed.  
 
TUXG01 Last Year of PEP-II B-Factory Operation luminosity, injection, vacuum, controls 946
 
  • J. Seeman
    SLAC, Menlo Park, California
  The PEP II B-Factory at SLAC has been in operation for a decade, delivering luminosity to the BABAR experiment. The design luminosity was successfully reached after one year of operation and since then it has surpassed over four times design at 1.2 x 1034 cm-2sec-1. History of main achievements, high current operation issues, and lessons for the future factories will be presented.  
slides icon Slides  
 
TUOAM01 Commissioning Status of the Shanghai Synchrotron Radiation Facility storage-ring, booster, injection, linac 998
 
  • Z. T. Zhao, H. Ding, H. Xu
    SINAP, Shanghai
  The Shanghai Synchrotron Radiation Facility (SSRF), an intermediate energy storage ring based third generation light source, is under commissioning at a site in Shanghai Zhang-Jiang Hi-Tech Park. The ground breaking of this project was made on Dec.25, 2004, and on Dec.24, 2007 electron beam was stored and accumulated in the SSRF storage ring. Since then the accelerator commissioning and beamline installation have been being continued toward the scheduled user operation from May 2009. This paper presents an overview of the SSRF status and its machine commissioning progress.  
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TUZM01 Recent Development of Diagnostics on 3rd Generation Light Sources emittance, diagnostics, electron, injection 1016
 
  • G. Rehm
    Diamond, Oxfordshire
  A Review of the most performing diagnostics on 3rd generation light sources will be given. Starting with the target performance specification of recent 3rd generation light sources, the demands for diagnostics will be highlighted. Topics include beam position monitors and their integration, emittance measurement by imaging of the stored beam or interference methods and diagnostic requirements for top-up operation. A survey on recent developments and the achieved performances at different accelerators will be presented.  
slides icon Slides  
 
TUZM02 Overview of Fast Beam Position Feedback Systems controls, electron, collider, synchrotron 1021
 
  • D. Bulfone
    ELETTRA, Basovizza, Trieste
  Modern circular and linear accelerators often rely on fast beam position feedbacks for the achievement of their design parameters. Such systems have gone through a significant evolution, which has taken advantage of recent progress of the associated equipment, like beam position monitors, as well as of the hardware and software processing technologies. A review of the latest developments and foreseen designs at different accelerators is given.  
slides icon Slides  
 
TUPC003 Libera Grouping: Reducing the Data Encapsulation Overhead brilliance, controls, monitoring, instrumentation 1041
 
  • A. Bardorfer, T. Karcnik
    Instrumentation Technologies, Solkan
  • K. T. Hsu
    NSRRC, Hsinchu
  Libera Brilliance is a precision digital Beam Position Monitor, a building block for modern fast orbit feedback systems. Gigabit Ethernet and UDP/IP protocol are used as a standard data link for real-time beam position signal transmission to the central fast feedback CPU engines. While the UDP/IP over Gigabit Ethernet provides a standardized and proven solution that enables the utilization of COTS components, the UDP and IP protocols are subject to a large data encapsulation overhead, since the beam position data payload is relatively small. To overcome this, several Libera Brilliance units (up to 16) have been grouped together in a redundant private network via the LC optical links and/or copper “Molex” cables. The purpose of the private network is to exchange the data among the Libera Brilliance units without the protocol overhead and send the gathered data via Gigabit Ethernet. Any of the Libera Brilliance units in a group can act as a Gigabit Ethernet group transmitter. The private network is redundant and can survive a single cable failure. The data encapsulation overhead has been significantly reduced. Libera Grouping is being tested at NSRRC, Taiwan.  
 
TUPC017 Beam Instrumentation System Development and Commissioning in SSRF booster, linac, storage-ring, diagnostics 1080
 
  • Y. B. Leng, J. Chen, Y. Z. Chen, Z. C. Chen, G. Q. Huang, D. K. Liu, Y. B. Yan, K. R. Ye, C. X. Yin, J. Yu, L. Y. Yu, R. Yuan, G. B. Zhao, L. Y. Zhao, W. M. Zhou, Y. Zou
    SINAP, Shanghai
  In recent months the first beams have been stored in the Storage Ring of the Shanghai Synchrotron Radiation Facility (SSRF). The brief introduction will be given of the beam diagnostics system development. The initial commissioning results including beam profile monitors, beam position monitors (BPMs), DC current monitors (DCCT), and synchrotron radiation monitor (SRM) will be reported in this paper.  
 
TUPC033 IP BPM Position Error at CLIC due to Secondary Emission from Beam-beam Backgrounds simulation, background, extraction, luminosity 1122
 
  • A. F. Hartin, R. Apsimon, P. Burrows, C. I. Clarke, C. Perry, C. Swinson
    OXFORDphysics, Oxford, Oxon
  • G. B. Christian
    ATOMKI, Debrecen
  • B. Constance, H. Dabiri Khah
    JAI, Oxford
  • A. Kalinin
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  Beam-beam background impacts on the IP BPM are studied for the CLIC machine. The large number of coherent pairs ( 1.8×108 charges per BPM strip per bunch crossing) for the CLIC-G default parameter set, potentially leads to a large secondary emission in the BPM strips. Detailed GuineaPig++ and Geant studies reveal, however, that the coherent pairs travel down the extraction line without significant secondary showering. Geant studies of the CLIC incoherent pairs show a flux of secondary emission two orders of magnitude less than that expected for the ILC 1 TeV high luminosity scheme. Since previous studies showed that FONT IP BPM signal distortion for the ILC was of no concern, then it can also be neglected at CLIC.  
 
TUPC043 Towards Sub-micrometer Resolution of Single Bunch Strip Line BPM pick-up, vacuum, coupling, simulation 1152
 
  • A. Kalinin
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  A high resolution single bunch BPM set-up is designed based on a strip line pickup. One of the BPM modifications developed is a Difference-Sum BPM. In this BPM, each strip line signal is converted into a three 600MHz square wave burst in a cascaded irregular strip line coupler. The Difference and Sum bursts produced by a hybrid junction are detected in a pair of synchronous detectors. The synchronous detector reference signals, and single-sample ADC triggers are manufactured from the Sum burst. The set-up and features of this BPM are presented. The BPM resolution was measured using a KEK ATF beam. For a bunch intensity above 109 electrons the resolution is about 1 μm (for BPM effective aperture 1/5). With appropriate ADCs, this BPM can measure individual bunches at a rate of up to 50 MHz. The BPM latency to the ADC inputs is as low as 10 ns. High resolution and low latency together, make this BPM suitable for beam-based fast feedback/feed-forward systems.  
 
TUPC044 Towards Routine Operation of the Digital Tune Monitor in the Tevatron proton, betatron, pick-up, antiproton 1155
 
  • V. Kamerdzhiev, V. A. Lebedev, A. Semenov
    Fermilab, Batavia, Illinois
  The digital tune monitor (DTM) was designed to measure bunch-by-bunch tunes in the Tevatron collider. It uses a standard BPM as a pickup. The vertical proton monitor is installed and allows us to gain valuable operational experience. A major upgrade is underway to implement an automatic bunch-by-bunch gain and offset adjustment to maintain the highest possible sensitivity under real operational conditions. Once the system is shown to be able to cope with orbit changes and different bunch intensities in an automatic manner while reliably delivering data it will be expanded to measure horizontal proton as well as antiproton tunes. The motivation and the technical description of the DTM as well as the latest experimental results are presented. Major challenges from the design and operation point of view are discussed.  
 
TUPC084 Combating Multi-bunch Instabilities with the Libera Bunch-by-bunch Unit betatron, kicker, single-bunch, target 1251
 
  • V. Poucki, T. Karcnik, P. L. Lemut, M. O. Oblak
    Instrumentation Technologies, Solkan
  Libera Bunch by Bunch is the digital processing unit for a bunch by bunch feedback system. The upgraded unit has a DSP core application featuring a 16 tap filter for each bunch. DSP processing is organized in 4 chains, following the HW implementation of A/D conversion. Besides setting of FIR filter coefficients in each processing chain, one bunch per chain can have different FIR filter coefficients and provides an option for 4 single bunch processing. All FIR filter coefficients are double buffered. Delays maximally equal to a revolution period are implemented before and after the FIR block. As an additional feature, a phase shift block is introduced that precisely shifts the phase of the output signal in the vicinity of a determined frequency. The core application is accompanied with a Matlab GUI, with an additional window for data acquisition. This system accompanied by a Front End unit provides a complete solution for combating multi bunch beam instabilities. A detailed description and results are presented.  
 
TUPC098 Results of the LHC Prototype Chromaticity Measurement System Studies in the CERN-SPS controls, betatron, coupling, emittance 1290
 
  • R. J. Steinhagen, A. Boccardi, T. Bohl, M. Gasior, O. R. Jones, J. Wenninger
    CERN, Geneva
  • K. K. Kasinski
    AGH, Cracow
  Tune and chromaticity control is an integral part of safe and reliable LHC operation. Tight tolerances on the maximum transverse beam excursions allow oscillation amplitudes of less than 30 um. This leaves only a small margin for transverse beam and momentum excitations required for measuring tune and chromaticity. This contribution discusses the baseline LHC continuous chromaticity measurement with results from tests at the CERN-SPS. The system is based on continuous tracking of the tune using a phase-locked-loop (PLL) while modulating the beam momentum. The high PLL tune resolution achieved ( ~1·10-6 ) made it possible to detect chromaticity changes well below the nominally required 1 unit for relative momentum modulations of only 2·10-5. The sensitive tune measurement front-end employed allowed the PLL excitation and radial amplitudes to be kept below a few tens of micrometers. These results show that this type of measurement can be considered as practically non-perturbative permitting its use even during nominal LHC operation.  
 
TUPC111 Overview of the Diagnostics Systems of PETRA III diagnostics, pick-up, emittance, laser 1323
 
  • G. Kube, K. Balewski, A. Brenger, H. T. Duhme, V. Gharibyan, J. Klute, K. Knaack, I. Krouptchenkov, T. Lensch, J. Liebing, D. Lipka, R. Neumann, R. Neumann, G. Priebe, F. Schmidt-Foehre, H.-Ch. Schroeder, R. Susen, S. Vicins, M. Werner, Ch. Wiebers, K. Wittenburg
    DESY, Hamburg
  Since mid-2007, the existing storage ring PETRA at DESY is reconstructed towards a dedicated third generation hard x-ray light source operating at 6 GeV with 100 mA stored current. The reconstruction includes the total rebuilding of one-eights of the storage ring. In this part the FODO lattice of the arcs is replaced by double-bend achromat cells, resulting in straight sections for 14 insertion device beamlines. Damping wigglers with a total length of 80 m are installed to reduce the emittance down to the design value of 1 nm rad. In order to fully benefit from this low emittance, beam stability is a crucial issue. For the achievement of the required performance and to allow a safe machine operation a number of beam instrumentation is required. Here the diagnostics system for the electron beam is presented with special emphasis on the essential instruments, i.e. the high resolution BPM system, profile monitors, feedback systems, and the machine protection system.  
 
TUPC119 Corrector Based Determination of Quadrupole Centres quadrupole, dipole, closed-orbit, storage-ring 1347
 
  • M. Sjöström, M. Eriksson, L.-J. Lindgren, E. J. Wallén
    MAX-lab, Lund
  A corrector magnet based method to determine the quadrupole magnet centres for storage rings has been tested on the MAX III synchrotron light source. The required corrector magnet strengths for the corrected beam orbit are used to determine the quadrupole magnet centre positions. This method is the most effective for an optimal distribution of beam position monitors and corrector magnets in the storage ring and will be used as a basis for the MAX IV storage rings.  
 
TUPC122 Feedback Corrections for Ground Motion Effects at ATF2 sextupole, quadrupole, optics, coupling 1353
 
  • Y. Renier, P. Bambade
    LAL, Orsay
  Ground motion will over time produce beam misalignments and size increases at the IP of the ATF2 beam line. The spatial and temporal characteristics of the vibrations measured on the site have been studied and model parameters have been fitted to allow reliably simulating the effects induced on the beam. A feedback loop to minimise the residual beam motion at the IP is considered, based on optimising the coefficients of a PID controller on both short and long time-scales.  
 
TUPC143 Precise RF Control System of the SCSS Test Accelerator controls, acceleration, radiation, electron 1404
 
  • H. Maesaka, T. Fukui, N. Hosoda, T. Inagaki, T. Ohshima, Y. Otake, H. Tanaka
    RIKEN/SPring-8, Hyogo
  • T. Hasegawa, S. Takahashi, S. Tanaka
    JASRI/SPring-8, Hyogo-ken
  • M. K. Kitamura
    NDS, OSAKA
  We present the development and performance of the low level rf control system of SCSS test accelerator (VUV-FEL facility). The FEL radiation in the wavelength region of 50-60 nm reached saturation in fall 2007. Since then, the FEL intensity fluctuation has been suppressed within 10%. This performance was achieved by stabilizing the rf phase and amplitude of the accelerator. For example, the rf phase stability of the 238 MHz cavity is achieved to be 0.03 degree rms corresponding to 350 fs. Those of other cavities such as C-band (5712MHz) accelerator are also obtained to be several 100 fs. To control the rf phase and amplitude precisely, we have developed an IQ modulator / demodulator system. To treat the baseband signal of the system, we have also developed VME high speed DAC / ADC boards. The phase skew of the IQ system is ± 1.0 degree without correction and ± 0.1 degree after correction. To suppress the slow drift of rf components, we applied a PID feedback control loop to the rf source and cavity system. We also improved temperature stabilization for the acceleration structures.  
 
TUPC144 Digital Low Level RF System for SOLEIL simulation, beam-loading, controls, synchrotron 1407
 
  • P. Marchand, M. D. Diop, F. Ribeiro, R. Sreedharan
    SOLEIL, Gif-sur-Yvette
  • M. Luong, O. Piquet
    CEA, Gif-sur-Yvette
  In the SOLEIL storage ring, two cryomodules, each containing a pair of 352 MHz superconducting cavities, will provide the maximum power of 560, required at the nominal energy of 2.75 GeV with the full beam current of 500 mA. Presently, an analogue Low Level RF system is successfully operating to control the amplitude and phase of the accelerating voltage. A fast digital FPGA based I-Q feedback is currently under development. The digital I-Q loop is realised with a HERON IO2 FPGA module using a Virtex II with 1M gates. The performance of the digital LLRF system has been evaluated using a Matlab-Simulink based simulation tool taking into account different features (loop delays, bandwidth limitation, extra power budget). The hardware design is described and the first experimental results are reported.  
 
TUPC145 FPGA Implementation of Multichannel Detuning Computation for SC Linacs controls, linac, resonance, diagnostics 1410
 
  • K. P. Przygoda, J. Andryszczak, W. Jalmuzna, A. Napieralski, T. Pozniak
    TUL-DMCS, Łódź
  The paper presents a multi-cavity system for active compensation of SC cavities' deformations in linear accelerators like Free Electron Laser. Described system consists of digital controller, analog amplifiers and mechanical actuators. The previously developed control algorithms were implemented in SIMCON 3.1 board and allow online calculations of Lorentz force detuning only for one cavity. The recent development in the field is based on serial pipelined computations which allow a real time detuning measurements of 8 and more cavities. Moreover, the SIMCON DSP board was used for 10 ns latency computations. The new approach enables integrating the algorithm dedicated for cavity shape control with the LLRF control system using optical transmission. Furthermore the 8-channels amplifiers have been successfully added to the compensation system for driving the piezoelectric actuators. The system is tested in FLASH at DESY. The accelerating modules ACC 3, 5 and 6 with high operating gradients cavities have been taken into account. The multilayer piezostacks from PI and NOLIAC are used for the compensation purpose of cavities' deformations.  
 
TUPC153 Hardware-software Simulation for LLRF Control System Development simulation, controls, monitoring, radio-frequency 1428
 
  • A. Vaccaro, L. R. Doolittle, A. Ratti, C. Serrano
    LBNL, Berkeley, California
  Field Programmable Gate Arrays (FPGA) have been used in accelerator controls for a long time. Stricter performance requirements in new accelerator designs force LLRF control systems to continuously improve, and the increasing density of available FPGAs enables such progress. The increased complexity in FPGA design is not always followed by new RF systems availability for development and testing. Therefore, a hardware-software simulation tool has been developed to model RF systems by a software simulator. It simulates the interaction of HDL code that is to be synthesized with both RF systems and communication ports to external controls software, reproducing realistic working conditions of the FPGA. The hardware-software interaction for LLRF control system design is discussed here.  
 
TUPD017 Design of Main Ring Dipole Power Supply for HIRFL-CSR power-supply, controls, dipole, heavy-ion 1464
 
  • Y. X. Chen, X. M. Feng, D. Q. Gao, Y. L. Gao, Y. Z. Huang, Y. Tang, J. J. Wang, J. W. Xia, H. B. Yan, H. H. Yan, Y. J. Yuan, Z. D. Yuan, S. Zhang, X. L. Zhang, Z. Z. Zhou
    IMP, Lanzhou
  This paper introduces the main circuit topologic, control method and double reference setting system of a dipole power supply which is the pivotal device of the HIRFL-CSR(Heavy Ion Research Facility in Lanzhou-Cooling Storage Ring). The power supply works at the pulse mode, with the peak output power of 3.15MW (3000A, 1045V). To fulfill difficult requirements especially for the tracking error, which is needed less than 300ppm, a special topologic is adopted. The power supply has two parts: SCR rectifier provides the most energy and PWM converter provides correcting current and perfect reaction for tracking current setting. Now the dipole power supply is performing well during the CSR commissioning, with the perfect tracking error, well long-time stability and low ripple current.  
 
TUPD019 Inter-disciplinary Mechanical and Architectural 3D CAD Design Process at the European XFEL controls, simulation, civil-engineering, cryogenics 1467
 
  • L. Hagge, N. Bergel, T. H. Hott, J. Kreutzkamp, S. Suehl, N. Welle
    DESY, Hamburg
  Realising the European-XFEL involves creating and coordinating several types of 3D design models for many different subsystems like underground buildings, utilities, accelerator systems or photon beam lines. In order to handle the huge amount of data, reduced envelope models are needed for integrating the subsystems towards the complete facility and to ensure that the different subsystems connect properly and do not intersect. Detailed component design models are required for planning approval, tendering or in-house production. A key issue was to develop an optimized design for the facilities while still being able to accommodate possible late R&D-driven design changes of subsystems. The paper describes the procedures and tools which are used for planning and designing the European-XFEL and reports benefits and experience. The procedures in use allow visualization of the facilities, negotiation of requirements and solutions between all the working groups, optimized storing of the documentation as well as running approval and change management procedures. Tools in use include a requirements database, 3D-CAD systems and an engineering data management system.  
 
TUPP001 Alternating Gradient Operation of Accelerating Modules at FLASH controls, electron, klystron, laser 1523
 
  • V. Ayvazyan, G. Petrosyan, K. Rehlich, S. Simrock, E. Vogel
    DESY, Hamburg
  • H. T. Edwards
    Fermilab, Batavia, Illinois
  The free electron laser in Hamburg (FLASH) is a user facility providing high brilliant laser light for experiments. It is also an unique facility for testing the superconducting accelerator technology for the European XFEL and the international linear collider (ILC). The XFEL offers several beam lines to users. Within limits given by the beam delivery system the bunch pattern and beam energy should be adjustable independent for each beam line suggesting a time sliced operation. The ILC is focused on the highest gradients possible. FLASH accelerates beam at 5 Hz repetition rate. During accelerator studies the operation of the last accelerating modules with 10 Hz and alternating rf pulses has been established proving the feasibility of a time sliced operation at the XFEL. The rf pulses synchronous to the 5 Hz rf pulses are used for FEL operation whereas the gradient of the remaining rf pulse can be chosen independently and is used for long term high gradient operation gaining experience for the ILC. The operation of two different gradients within a single rf pulse is also available. The paper describes the technical setup, the rf control performance and the operational experience.  
 
TUPP002 Uniform Motion Control Solution for Variety of Motion Applications controls, acceleration, power-supply, insertion 1526
 
  • J. Dedic, G. Jansa, M. Plesko, R. Sabjan
    Cosylab, Ljubljana
  Control solutions for motion applications require high degree of flexibility regarding the use and connectivity. Being fairly simple or highly complex, micro- or millimeter precision, one or multiple axis… the system designer has to tackle specific interfacing issues. One platform should fit different applications and provide cost effective solutions. Flexible software platform is required on one side to satisfy control system (CS) application requirements. On the other side variety of hardware (HW)–controlled by motion controller, i.e., power stages, position feedback–also requires some degree of connection flexibility. Paper presents a design of a motion control platform that offers flexible interfacing both to CS and HW, elegant extendibility options for selection of feedback protocols, low-level direct access for engineering control and enables large distances between controller and motors.  
 
TUPP008 An Automatic Control System for Conditioning 30 GHz Accelerating Structures controls, gun, vacuum, target 1541
 
  • A. Dubrovsky, J. A. Rodriguez
    CERN, Geneva
  A software application programme has been developed to allow fast, automatic, conditioning of the accelerating structures to be high-gradient tested at 30 GHz in CTF3. The specificity of the application is the ability to control a high power electron beam which produces the 30 GHz RF power used to condition the accelerating structures. It significantly increases the amount of time useable for high power conditioning. In this paper this fast control system, the machine control system, the logging system, the graphic user control interface and the logging data visualization are described. An outline of the conditioning control system itself and of the feedback controlling peak power and pulse length is given. The software allows different types of conditioning strategies to be programmed.  
 
WEOBG04 First Experimental Results from DEGAS, the Quantum Limited Brightness Electron Source laser, electron, brightness, controls 1918
 
  • M. S. Zolotorev, J. W. ONeill, F. Sannibale, W. Wan
    LBNL, Berkeley, California
  • E. D. Commins, A. S. Tremsin
    UCB, Berkeley, California
  The construction of DEGAS (DEGenerate Advanced Source), a proof of principle for a quantum limited brightness electron source, has been completed at the Lawrence Berkeley National Laboratory. The commissioning and the characterization of this source, designed to generate coherent low energy (10-100 eV) single electron "bunches" with brightness approaching the quantum limit at a repetition rate of few MHz, has been started. In this paper the first experimental results are described.  
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WEOCG01 Orbit Feedback Trickery at the NSLS VUV Ring controls, simulation 1931
 
  • B. Podobedov
    BNL, Upton, Long Island, New York
  A couple of NSLS user groups has recently requested an unusual modification to the way the VUV ring orbit is controlled and stabilized. Rather than keeping the orbit as stable as possible they require a large (many transverse beam sizes) periodic orbit oscillation at the source points of their beamlines. During regular machine operations this has to co-exist with stable orbit throughout the rest of the ring. Achieving good orbit stability under these constraints presents an interesting control problem. Making use of control theory tools and Matlab / Simulink modeling we have explored various algorithms to allow for these new requirements. We then extended our digital orbit feedback system to incorporate these algorithms. In this paper we present commissioning results as well as comparison to the simulations.  
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WEOBM02 Lessons Learned from PEP-II LLRF and Longitudinal Feedback controls, klystron, simulation, kicker 1953
 
  • J. D. Fox, T. Mastorides, C. H. Rivetta, D. Van Winkle
    SLAC, Menlo Park, California
  • D. Teytelman
    Dimtel, San Jose
  The PEP-II B Factory is in the final phase of operation at 2X the design current and 4X the design luminosity. Since the original design the machine has added 8 1.2 MW Klystrons and 12 RF cavities, and the machine is operating with longitudinal instability growth rates roughly 5X in excess of the original estimates. Since commissioning there has been continual adaptation of the LLRF control strategies, configuration tools and new hardware in response to unanticipated technical challenges. This paper presents the LLRF and feedback system evolution from the original design estimates through to the 1.2·1034 final machine. We highlight issues of RF station stability, the interplay of LLRF configuration and low-mode (cavity fundamental driven) longitudinal instabilities, impacts of non-linearities and imperfections in the LLRF electronics, control of HOM driven beam instabilities and the development of configuration tools and measurement techniques to optimally configure the LLRF over the wide range of operating currents. We present valuable "lessons learned" which are of interest to designers of next generation impedance controlled LLRF systems.  
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WEIM05 Institutional and Industrial Partnerships linac, synchrotron, controls, instrumentation 1972
 
  • C. J. Bocchetta
    Instrumentation Technologies, Solkan
  To be successful, accelerator projects require close interaction with industry for design, engineering and construction. Partnership and cooperation between institutes and industry is a means to transfer knowledge and foster innovation in the private sector, while the public sector benefits from best practices, efficient use of resources and pooled knowledge. An overview of partnerships between institutions and industry is given with examples from active projects.  
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WEPC002 Analysis of Beam Orbit Stability and Ground Vibrations at the Diamond Storage Ring resonance, quadrupole, ground-motion, storage-ring 1980
 
  • R. Bartolini, H. C. Huang, J. Kay, I. P.S. Martin
    Diamond, Oxfordshire
  With the aim of understanding and improving the beam orbit stability at the Diamond storage ring we launched an extensive campaign of ground and magnets vibration measurements in order to identify the sources of ground vibration and how they affect the beam orbit stability through the girder resonances. We present here the results of the measurements performed during 2007 along with a discussion of the possible remedies and the implications for the orbit feedback systems.  
 
WEPC008 Status of the SSRF Storage Ring storage-ring, site, superconducting-RF, vacuum 1998
 
  • Z. M. Dai, D. K. Liu, L. G. Liu, L. Yin, Z. T. Zhao
    SINAP, Shanghai
  The SSRF storage ring is composed of 20 DBA cells with energy of 3.5GeV and circumference of 432m. The installation of the SSRF storage ring was started on June 11, 2007, and finished in the beginning of Dec. 2007. The system tests of hardware and software for storage ring were completed in the middle of Dec. 2007. The commissioning of the storage ring started on Dec. 21, 2007, and the 100mA stored beam was achieved for the first time on Jan. 3, 2008. The design, installation and commissioning of the SSRF storage ring are described in this paper  
 
WEPC016 Operation Status and Performances Upgrade on SOLEIL Storage Ring undulator, vacuum, photon, insertion 2022
 
  • J.-M. Filhol, J. C. Besson, F. Bouvet, P. Brunelle, L. Cassinari, M.-E. Couprie, J.-C. Denard, C. Herbeaux, J.-F. Lamarre, J.-P. Lavieville, P. Lebasque, M.-P. Level, A. Loulergue, P. Marchand, A. Nadji, L. S. Nadolski, R. Nagaoka, M.-A. Tordeux
    SOLEIL, Gif-sur-Yvette
  SOLEIL is the French 2.75 GeV third generation synchrotron light source delivering beam to users since January 2007. Beginning of 2008 up to 13 beam-lines are taking beam, 7 from insertion devices (IDs), 2 from IR ports, and 4 from dipole ports, and 6 of them are open to external Users. Users have a full control of their IDs. With a 300 mA stored beam current in multi-bunch filling pattern, and position stability in the few micron range, the main target performances have been reached. A beam of 50 mA in 8 bunches was delivered to users for the first time in December 2007 for time structure experiments. Operation and performance status will first be given, namely subsystem behaviour (RF, vacuum, …), beam optics, orbit stability, beam lifetime, and operation statistics. Then the main objectives for 2008 will be reviewed: delivery of 4000 hours of user beam time, installation and commissioning of a second cryomodule for reaching the 500 mA current target, construction and installation of 6 new IDs leading to a total number of 17, improvement of the orbit stability with a fast orbit feedback complementary to the slow orbit one, and preparation for top-up operation.  
 
WEPC022 Operation and Recent Developments at the ESRF undulator, storage-ring, lattice, cryogenics 2028
 
  • J.-L. Revol, J. C. Biasci, J-F. B. Bouteille, J. M. Chaize, J. Chavanne, P. Elleaume, L. Farvacque, G. Gautier, L. Goirand, M. Hahn, L. Hardy, J. Jacob, R. Kersevan, J. M. Koch, J. M. Mercier, I. Parat, C. Penel, T. P. Perron, E. Plouviez, A. Ropert, K. B. Scheidt, D. Schmied, V. Serriere
    ESRF, Grenoble
  The ESRF has been operating for a period close to fifteen years and is now looking towards an ambitious upgrade programme for the coming ten years. This paper reports on the performances achieved today with the ESRF storage ring, as well as developments accomplished and projects underway. These include a new filling mode for pump and probe experiments, the evolution of insertion devices, developments to improve beam stability, in particular transverse and longitudinal multibunch feedbacks, and the current increase from 200 to 300 mA. The upgrade of the lattice to accommodate longer straight sections and the new High Quality Power Supply system will also be presented. The machine reliability and the most important failures will be discussed. Finally, the use of an electronic logbook in routine operation will be presented, and the status on the control system including TANGO collaboration given.  
 
WEPC030 Diamond Light Source: Moving from Commissioning to Full Machine Operation injection, storage-ring, single-bunch, controls 2052
 
  • V. C. Kempson
    Diamond, Oxfordshire
  Diamond Light Source commenced routine operations in January 2007 providing light to beam lines for 3000 hours in 2007 with 4000 hours planned during 2008. During shut down periods Insertion Devices and photon Beam Lines, to utilise them, are being installed at a rate of four per year. The evolution of the performance of the machine during this period is described, including beam current, vacuum levels, beam lifetime etc. Machine operational statistics are also presented including a detailed fault analysis. Efforts that have been made to improve reliability are also discussed. On behalf of the Diamond machine staff.  
 
WEPC043 Commissioning of 360 mA Top-up Operation at TLS injection, booster, insertion, insertion-device 2082
 
  • Y.-C. Liu, H.-P. Chang, K.-K. Lin, Y. K. Lin, G.-H. Luo
    NSRRC, Hsinchu
  Taiwan light source started the 200 mA top-up operation in October, 2005, and subsequently, the stored top-up beam current was raised to 300 mA. Several machine issues were observed and solved during past two years. We study the possibility and ability of 360 mA top-up operation at Taiwan light source.  
 
WEPC058 Operational Performance of the Taiwan Light Source photon, injection, synchrotron, synchrotron-radiation 2124
 
  • Ch. Wang, H.-P. Chang, J.-C. Chang, J.-R. Chen, F.-T. Chung, F. Z. Hsiao, G.-Y. Hsiung, K. T. Hsu, C. K. Kuan, C.-C. Kuo, K. S. Liang, K.-K. Lin, Y.-H. Lin, K.-B. Liu, Y.-C. Liu, G.-H. Luo, R. J. Sheu, D.-J. Wang, M.-S. Yeh
    NSRRC, Hsinchu
  The Taiwan light source (TLS) is a 1.5 GeV third generation light source at the National Synchrotron Radiation Research Center (NSRRC) in Taiwan. It has been routinely operated since its opening in 1993. Several major machine upgrade projects have been undertaken and successfully completed in last 5 years, including implementing of digital bunch-by-bunch feedbacks, superconducting accelerating RF cavity, top-up mode injection, etc. The light source now moves forward to its era of mature operation. It delivers more than 5000 hours user time in 2007 with an up-time of more than 98% and a mean time between failures better than 80 hours. Here, we review its annual operational performance with detailed statistics and discuss the possible improvement directions of machine performance.  
 
WEPC108 Portable Magnetic Field Measurement System controls, laser, vacuum, undulator 2252
 
  • J. Kulesza, A. Deyhim, E. Van Every, D. J. Waterman
    Advanced Design Consulting, Inc, Lansing, New York
  • K. I. Blomqvist
    MAX-lab, Lund
  This portable magnetic field measurement system is a very sophisticated and sensitive machine for the measurement of magnetic fields in undulators (Planer, EPU, and Apple II), wigglers, and in-vacuum ID units. The magnetic fields are measured using 3 axis hall-effect probes, mounted orthogonally to a thin wand. The wand is mounted to a carriage that rides on vacuum air bearings. The base is granite. A flip coil is provided on two vertical towers with X, Y and Theta axes. Special software is provided to assist in homing, movement, and data collection.  
 
WEPP008 Localizing Sources of Horizontal Orbit Oscillations at RHIC closed-orbit, luminosity, emittance, focusing 2539
 
  • R. Calaga, R. J. Michnoff, T. Satogata
    BNL, Upton, Long Island, New York
  Horizontal oscillations of the closed orbit at frequencies around 10Hz are observed at RHIC. These oscillations lead to beam beam offsets at the collision point, resulting in emittance growth and reduced luminosity. An approach to localize the sources of these vibrations using a special mode of RHIC turn-by-turn BPM data is presented. Data from the 2005-06 are analyzed to spatially resolve the location of the dominant sources.  
 
WEPP011 Setup and Performance of RHIC for the 2008 Run with Deuteron and Gold Collisions luminosity, ion, injection, lattice 2548
 
  • C. J. Gardner, N. P. Abreu, L. Ahrens, J. G. Alessi, M. Bai, D. S. Barton, J. Beebe-Wang, M. Blaskiewicz, J. M. Brennan, K. A. Brown, D. Bruno, J. J. Butler, P. Cameron, C. Carlson, R. Connolly, T. D'Ottavio, A. J. Della Penna, K. A. Drees, W. Fischer, W. Fu, G. Ganetis, J. W. Glenn, M. Harvey, T. Hayes, H. Huang, P. F. Ingrassia, J. Kewisch, R. C. Lee, V. Litvinenko, Y. Luo, W. W. MacKay, M. Mapes, G. J. Marr, A. Marusic, R. J. Michnoff, C. Montag, J. Morris, B. Oerter, F. C. Pilat, E. Pozdeyev, V. Ptitsyn, G. Robert-Demolaize, T. Roser, T. Russo, P. Sampson, J. Sandberg, T. Satogata, C. Schultheiss, F. Severino, K. Smith, D. Steski, S. Tepikian, R. Than, P. Thieberger, D. Trbojevic, N. Tsoupas, J. E. Tuozzolo, A. Zaltsman, K. Zeno, S. Y. Zhang
    BNL, Upton, Long Island, New York
  This year deuterons and gold ions were collided in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) for the first time since 2003. The setup and performance of the collider for this run is reviewed with a focus on improvements that have led to an order of magnitude increase in luminosity since the 2003 run.  
 
WEPP041 High-current Effects in the PEP-II Storage Rings kicker, vacuum, impedance, ion 2611
 
  • U. Wienands, W. X. Cheng, W. S. Colocho, S. DeBarger, F.-J. Decker, S. Ecklund, A. S. Fisher, D. Kharakh, A. Krasnykh, A. Novokhatski, M. K. Sullivan
    SLAC, Menlo Park, California
  High beam currents, 2A(HER) & 3A(LER), in PEP-II has been a challenge for the vacuum system. For the ~1 cm long bunches peak currents reach 50 A. Thus modest impedances can give rise to voltage spikes and discharges. A weakness was uncovered during Run 6: rf seals at the "flex flanges" that join the HER arc dipole and quadrupole chambers became a source of an increasing number of HER beam aborts. Vacuum activity was seen and thermal sensors on these flanges saw temperature spikes. Inspection of the seals found arcing and melting, prompting us to replace all of these seals with an improved design using Inconel instead of GlidCop fingers. We believe the GlidCop fingers do not maintain elasticity and hence can not follow chamber motion due to thermal effects. The Run 7 startup confirmed the success of this repair. However, high bunch current in the LER caused breakdown in a LER kicker. This limited the LER bunch current to about 1 mA. Inspection revealed damage to one of the recently added Macor pins that help support the electrodes. Failure analysis revealed heating of the pin & post-facto modeling shows high fields coming from a combination of HOM impedance and high peak currents.  
 
WEPP060 Abort Gap Cleaning Using the Transverse Feedback System: Simulation and Measurements in the SPS for the LHC Beam Dump System simulation, octupole, kicker, proton 2656
 
  • A. Koschik, B. Goddard, W. Höfle, G. Kotzian, D. K. Kramer, T. Kramer
    CERN, Geneva
  The critical and delicate process of dumping the beams of the LHC requires very low particle densities within the 3 microseconds of the dump kicker rising edge. High beam population in this so-called 'abort gap' might cause magnet quenches or even damage. Constant refilling due to diffusion processes is expected which will be counter-acted by an active abort gap cleaning system employing the transverse feedback kickers. In order to assess the feasibility and performance of such an abort gap cleaning system, simulations and measurements with beam in the SPS have been performed. Here we report on the results of these studies.  
 
WEPP084 Fabrication of a Quadrant-type Accelerator Structure for CLIC linear-collider, collider, acceleration, background 2716
 
  • T. Higo, Y. Higashi, H. Kawamata, T. T. Takatomi, K. Ueno, Y. Watanabe, K. Yokoyama
    KEK, Ibaraki
  • A. Grudiev, G. Riddone, M. Taborelli, W. Wuensch, R. Zennaro
    CERN, Geneva
  In order to heavily damp the higher order modes of an accelerator structure for CLIC, two kind of damping mechanisms are implemented in one of the designs. Here each cell is equipped with electrically coupled damping channels in addition to the magnetically coupled waveguides. This design requires an assembly of longitudinally cut four quadrants to form a structure and the parts are necessarily made with milling. Since KEK has developed a high-precision machining of X-band accelerator cells with milling and turning at the same time, the experience was extended to the milling of this quadrant. Firstly, the fabrication test of a short quadrant was performed with multiple vendors to taste the present-day engineering level of milling. Following this, a full-size quadrant is also made. In this course, some of the key features are addressed, such as flatness of the reference mating surfaces, alignment grooves, 3D profile shape of the cells, surface roughness and edge treatment. In this paper, these issues are discussed from both fabrication and evaluation point of views.  
 
WEPP163 Measurements of Collimator Wakefields at End Station A simulation, radiation, linear-collider, collider 2868
 
  • J.-L. Fernandez-Hernando
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • S. Molloy
    SLAC, Menlo Park, California
  • J. D.A. Smith
    Cockcroft Institute, Warrington, Cheshire
  • N. K. Watson
    Birmingham University, Birmingham
  The angular kicks imparted to an electron beam with energy of 28.5 GeV when it passes through a collimator jaw with a certain offset, generating a wakefield, were measured in End Station A (ESA) in SLAC for fifteen different collimator configurations of geometry and material. Some configurations were chosen in order to compare with previous measurements while others served to study the effect of geometry and taper angles (geometrical contribution to the wakefield) and the effect of the material resistivity (resistive contribution) to the kick. This paper summarises the final experimental results. The reconstructed kick factor is compared to analytical calculations and simulations.  
 
THPPGM01 A Control and Systems Theory Approach to the High Gradient Cavity Detuning Compensation controls, resonance, coupling 2952
 
  • R. Paparella
    INFN/LASA, Segrate (MI)
  The compensation of dynamic detuning is of primary importance in order to operate TESLA type cavities at the high accelerating gradient foreseen for the ILC (31.5 MV/m). This article firstly resumes recent successful experiences of open loop compensation of the Lorentz force detuning, repetitive and synchronous to the RF pulse, using fast piezoelectric actuators with different fast tuning systems. Possible strategies and results for the closed loop compensation of the stochastic microphonic detuning are also presented. Lastly, a deep characterization of the system under control is given, exploiting the system transfer functions acquired through both installed piezo actuators/sensors and phase locked measurements. This ultimately allows the analytical modeling of the behavior of cavity detuning and of its active compensation with piezoelectric actuators.  
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THPC024 Closed Orbit Correction at the LNLS UVX Storage Ring coupling, sextupole, storage-ring, optics 3029
 
  • L. Liu, R. H.A. Farias, X. R. Resende, P. F. Tavares
    LNLS, Campinas
  The orbit correction of stored electrons in the LNLS storage ring often needs a few iterations to converge to the smallest distortion. This is caused in part by the residual coupling between transverse planes. This coupling effect can be included in the correction algorithm leading to the best orbit in just one iteration. However, in the LNLS ring, the number of monitors equals the number of vertical correctors but surpasses the number of horizontal correctors. This means that the vertical orbit can be corrected to zero at the position monitors in the decoupled situation but the horizontal orbit cannot. For the coupled case, the incapacity of zeroing the horizontal orbit leaks into the vertical plane. This problem can be addressed by the eigenvector method with constraints.  
 
THPC065 Orbit Stability Status and Improvement at SOLEIL power-supply, booster, target, injection 3134
 
  • L. S. Nadolski, J. C. Besson, F. Bouvet, P. Brunelle, L. Cassinari, J.-C. Denard, J.-M. Filhol, N. Hubert, J.-F. Lamarre, A. Loulergue, A. Nadji, D. Pedeau, M.-A. Tordeux
    SOLEIL, Gif-sur-Yvette
  SOLEIL is a 2.75 GeV third generation synchrotron light source delivering photons to beam-lines since January 2007. Stability of the beam-line source points is crucial for the user experiments. Typically this stability has to be below one tenth of the transverse beam sizes. This is challenging especially in the vertical plane leading to sub-micrometer values. This paper will describe the position stability achieved today without and with the slow orbit feedback. Impact of different noise sources and present limitations will be described. To end an improvement strategy will be given for short and medium terms.  
 
THPC113 Feedback Damper System for Quadrupole Oscillations after Transition at RHIC quadrupole, damping, emittance, heavy-ion 3242
 
  • N. P. Abreu, M. Blaskiewicz, J. M. Brennan, C. Schultheiss
    BNL, Upton, Long Island, New York
  The heavy ion beam at RHIC undergoes a strong quadrupole oscillations just after it crosses transition, which in turn leads to an increase in bunch length making rebucketing less effective. A feedback system was built to damp these quadrupole oscillations and in this paper the characteristics of the system and the results obtained are presented and discussed.  
 
THPC114 Design and Performance of a Prototype Digital Feedback System for the International Linear Collider Interaction Point kicker, linear-collider, collider, extraction 3245
 
  • P. Burrows, B. Constance, H. Dabiri Khah, J. Resta-López
    JAI, Oxford
  • R. Apsimon, P. Burrows, C. I. Clarke, A. F. Hartin, C. Perry, C. Swinson
    OXFORDphysics, Oxford, Oxon
  • G. B. Christian
    ATOMKI, Debrecen
  • A. Kalinin
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  We present the design and preliminary results of a prototype beam-based digital feedback system for the Interaction Point of the International Linear Collider. A custom analogue front-end processor, FPGA-based digital signal processing board, and kicker drive amplifier have been designed, built, and tested on the extraction line of the KEK Accelerator Test Facility (ATF). The system was measured to have a base latency of approximately 140 ns, increasing to approximately 148 ns with the inclusion of real-time charge normalisation.  
 
THPC115 Commissioning of SOLEIL Fast Orbit Feedback system photon, storage-ring, insertion, controls 3248
 
  • N. Hubert, L. Cassinari, J.-C. Denard, J.-M. Filhol, N. Leclercq, A. Nadji, L. S. Nadolski, D. Pedeau
    SOLEIL, Gif-sur-Yvette
  The Fast Orbit Feedback system at SOLEIL is fully integrated into the BPM system equipped with Libera modules. Indeed, the correction algorithm has been embedded into the Libera FPGA which directly drives the power supplies of dedicated air coil correctors. The beam position measurements of the 120 BPMs are distributed around the storage ring by a dedicated network. Then, the correction is computed and applied at a rate of 10 kHz to 48 correctors installed over stainless-steel bellows, on each side of every straight section. The BPM system has been operational for some time. The fast orbit feedback system is in its commissioning phase. The design and first results of the latter are reported.  
 
THPC116 Commissioning of the iGp Feedback System at DAΦNE single-bunch, betatron, controls, diagnostics 3251
 
  • A. Drago
    INFN/LNF, Frascati (Roma)
  • J. D. Fox
    SLAC, Menlo Park, California
  • D. Teytelman
    Dimtel, San Jose
  • M. Tobiyama
    KEK, Ibaraki
  The iGp (Integrated Gigasample Processor) is an innovative digital bunch-by-bunch feedback system developed by a KEK/SLAC/INFN-LNF joint collaboration. The processing unit can sample at 500 MHz and compute the bunch-by-bunch output signal for up to 5000 bunches. The feedback firmware code is implemented inside just one FPGA (Field Programmable Gate Array) chip, a Xilinx Virtex-II. The FPGA implements two 16 taps FIR (Finite Impulse Response) filter that are realtime programmable through the operator interface. At DAΦNE, the Frascati PHI-Factory, two iGp units have been commissioned in the April 2007. The iGp systems have plugged in the previous betatron feedback systems. This insertion has been very fast and has shown no problems involving just a substitution of the old, less flexible, digital unit, letting unchanged the baseband analog frontend and the analog backend. The commissioning has been very simple, due to the complete and powerful EPICS operator interface, working well in local and remote operations. The software includes also tools for analyzing post processor data. A description of the commissioning with the operations done to find the best feedback setup are reported.  
 
THPC117 Measurements and Analysis of Beam Transfer Functions in the Fermilab Recycler Ring Using the Transverse Digital Damper System diagnostics, pick-up, kicker, antiproton 3254
 
  • N. Eddy, J. L. Crisp, M. Hu
    Fermilab, Batavia, Illinois
  The Fermilab Recycler Ring Transverse Digital Damper System was designed to facilitate Beam Transfer Function measurements using a Network Analyzer connected to auxiliary system ports for timing and diagnostic purposes. The Digital Damper System has the capability for both open and closed loop measurements. The Beam Transfer Function measurements provide direct measurements of the machine impedance, beam stability, and beam parameters such as betatron tune and chromaticity. An overview of the technique is presented along with analysis and results from open and closed loop measurements in the Fermilab Recycler Ring.  
 
THPC118 Performance and Future Developments of the Diamond Fast Orbit Feedback System electron, controls, storage-ring, target 3257
 
  • M. T. Heron, M. G. Abbott, J. A. Dobbing, G. Rehm, J. Rowland, I. Uzun
    Diamond, Oxfordshire
  • S. Duncan
    University of Oxford, Oxford
  The electron beam in the Diamond Synchrotron Light Source is stabilised in two planes using a Global Beam Orbit Feedback system. This feedback system takes the beam position from 168 Libera electron beam position monitors, for both planes, and calculates offsets to 336 corrector power supplies at a rate ~10kHz. The design and implementation will be summarised, and system performance and first operational experience presented. Current and potential future developments of the system will be considered.  
 
THPC119 Progress of TLS Fast Orbit Feedback System and Orbit Stability Studies power-supply, controls, simulation, brilliance 3260
 
  • C. H. Kuo, J. Chen, P. C. Chiu, K. T. Hsu, K. H. Hu, D. Lee
    NSRRC, Hsinchu
  The orbit feedback system of the TLS has been deployed for a decade and continuously upgraded. However, due to limitation of the existing hardware, the system cannot remove orbit excursion caused by the perturbation due to fast operation of insertion devices. The newly proposed orbit feedback system with the upgraded digital BPM system and switching corrector power supply system is planned to be installed and commissioned in late 2008. The preliminary calculation on the stability performance for the orbit feedback system is presented in the report. New fast orbit feedback system can be expected to achieve a submicron stability of the electron beam working at a bandwidth of at least 60 Hz.  
 
THPC120 Conceptual Design and Performance Estimation of The TPS Fast Orbit Feedback System power-supply, controls, vacuum, closed-orbit 3263
 
  • P. C. Chiu, J. Chen, K. T. Hsu, K. H. Hu, C. H. Kuo
    NSRRC, Hsinchu
  A 3 GeV Synchrotron (TPS) is proposed in Taiwan. Its storage ring consists of 24 double-bend cells with 6-fold symmetry and the circumference is 518.4m. The report presents the initial design of the fast orbit feedback system (FOFB) for TPS. The system uses 168 BPMs and 168 correct magnets to stabilize global closed orbit at 10 kHz updated rate. The different subsystems are modeled: the BPM systems, the corrector magnet, vacuum chamber, and etc. The latency of the communication and computation is also studied. The preliminary calculation on the stability performance for the orbit feedback system is presented in the report. The FOFB is expected to achieve a submicron stability of the electron beam working at a bandwidth of at least 100 Hz.  
 
THPC121 LHC Transverse Feedback System and its Hardware Commissioning kicker, injection, vacuum, damping 3266
 
  • W. Höfle, P. Baudrenghien, F. Killing, Y. A. Kojevnikov, G. Kotzian, R. Louwerse, E. Montesinos, V. Rossi, M. Schokker, E. Thepenier, D. Valuch
    CERN, Geneva
  • E. V. Gorbachev, N. I. Lebedev, A. A. Makarov, S. Rubtsun, V. Zhabitsky
    JINR, Dubna, Moscow Region
  A powerful transverse feedback system ('damper') has been installed in LHC. It will stabilise coupled bunch instabilities in a frequency range from 3 kHz to 20 MHz and at the same time damp injection oscillations originating from steering errors and injection kicker ripple. The transverse damper can also be used as an exciter for purposes of abort gap cleaning or tune measurement. The power and low-level systems layout are described along with results from the hardware commissioning. The achieved performance is compared with earlier predictions and requirements for injection damping and instability control. Requirements and first measurements of the performance of the low-level system are summarized. The chosen approach for the low-level system using advanced FPGA technology is very flexible allowing implementation of future upgrades of the signal processing without changing the hardware.  
 
THPC122 Digital Signal Processing for the Multi-bunch LHC Transverse Feedback System pick-up, kicker, betatron, damping 3269
 
  • W. Höfle, P. Baudrenghien, G. Kotzian, V. Rossi
    CERN, Geneva
  For the LHC a VME card has been developed that contains all functionalities for transverse damping, diagnostics and controlled bunch by bunch excitation. It receives the normalized bunch by bunch position from two pick-ups via Gigabit Serial Links (SERDES). A Stratix II FPGA is responsible for resynchronising the two data streams to the bunch-synchronous clock domain (40.08 MHz) and then applying all the digital signal processing: In addition to the classic functionalities (gain balance, rejection of closed orbit, pick-up combinations, one-turn delay) it contains 3-turn Hilbert filters for phase adjustment with a single pick-up scheme, a phase equalizer to correct for the non-linear phase response of the power amplifier and an interpolator to double the processing frequency followed by a low-pass filter to precisely control the bandwidth. Using two clock domains in the FPGA the phase of the feedback loop can be adjusted with a resolution of 10 ps. Built-in diagnostic memory (observation and post-mortem) and excitation memory for setting-up are also included. The card receives functions to continuously adjust its parameters as required during injection, ramping and physics.  
 
THPC123 The PSI DSP Carrier (PDC) Board - a Digital Back-end for Bunch-to-bunch and Global Orbit Feedbacks in Linear Accelerators and Storage Rings controls, kicker, storage-ring, undulator 3272
 
  • B. Keil, R. Kramert, G. Marinkovic, P. Pollet, M. Roggli
    PSI, Villigen
  PSI has developed a signal processing VXS/VME64x board for accelerator applications like low-latency bunch-to-bunch feedbacks, global orbit feedbacks or low-level RF systems. The board is a joint development of PSI/SLS staff and staff working on the contribution of PSI for the European X-ray FEL (E-XFEL). Future applications of the board include the Intra-Bunchtrain Feedback (IBFB) of the E-XFEL as well as the upgrade of the SLS Fast Orbit Feedback (FOFB) and Multibunch Feedback (MBFB). The PDC board has four Virtex-4 FPGAs, two TS201 Tiger Sharc DSPs, VXS and VME64x 2eSST interfaces, and two front panel SFP multi-gigabit fibre optic links. Two 500-pin LVDS/multi-gigabit mezzanine connectors allow to interface the FPGAs to two application-dependent mezzanine modules each containing e.g. four 500 Msps 12-bit ADCs and two 14-bit DACs for the IBFB and MBFB, or four multi-gigabit SFP fibre optic transceivers for the FOFB. This paper reports on hardware and firmware concepts, system topologies and synergies of future applications.  
 
THPC124 The Manufacturing and Tests of The New Vertical Feedback Stripline at Soleil impedance, vacuum, simulation, kicker 3275
 
  • C. Mariette, J.-C. Denard, R. Nagaoka
    SOLEIL, Gif-sur-Yvette
  This paper describes the development of the kicker striplines for the bunch-by-bunch transverse instability feedback system at Soleil. A careful design of the striplines and of their vacuum feedthroughs was aimed at maximizing the effectiveness of the excitation power and minimizing the power taken from the beam. The excitation effectiveness improves with the shunt impedance. But, simultaneously, the beam impedance should be made as small as possible. We also found useful to estimate the temperature of the feedthroughs at high beam currents, especially on the ceramic-to-metal seals. We also report on the difficulties encountered with obtaining good feedthroughs.  
 
THPC125 Modeling and Simulation of the Longitudinal Beam Dynamics-RF Station Interaction in the LHC Rings simulation, klystron, impedance, controls 3278
 
  • T. Mastorides, J. D. Fox, C. H. Rivetta, D. Van Winkle
    SLAC, Menlo Park, California
  • P. Baudrenghien, J. Tuckmantel
    CERN, Geneva
  A non-linear time-domain simulation has been developed to study the interaction between longitudinal beam dynamics and RF stations in the LHC rings. The motivation for this tool is to study the effect of RF station noise, impedance, and perturbations on the beam life and longitudinal emittance. It will be also used to determine optimal LLRF configurations, to study system sensitivity on various parameters, and to define the operational and technology limits. It allows the study of alternative LLRF implementations and control algorithms. The insight and experience gained from our PEP-II simulation is important for this work. In this paper we discuss properties of the simulation tool that will be helpful in analyzing the LHC RF system and its initial results. Partial verification of the model with data taken during the LHC RF station commissioning is presented.  
 
THPC126 Performance and Features of the Diamond TMBF System damping, controls, single-bunch, pick-up 3281
 
  • A. F.D. Morgan, G. Rehm, I. Uzun
    Diamond, Oxfordshire
  The Diamond Transverse Multibunch Feedback System (TMBF) comprises an in-house designed and built analogue frontend to select and condition the position signals for each bunch. This is combined with the Libera Bunch-by-Bunch system to digitise the signal and perform the relevant calculations before driving the output stripline kickers. As the electronics are based on an FPGA this has allowed us to implement several features in addition to the basic feedback calculations. We report on improvements to both the analogue and digital parts of the TMBF system, along with recent achievements in using the system for instability mode stabilisation and for tune measurement. Also we discuss the potential of the system and additional functionality we plan on introducing in the near future.  
 
THPC127 Filling of High Current Singlet and Train of Low Bunch Current in SPring-8 Storage Ring injection, kicker, betatron, damping 3284
 
  • T. Nakamura, T. Fujita, K. Fukami, K. Kobayashi, C. Mitsuda, M. Oishi, S. Sasaki, M. Shoji, K. Soutome, M. Takao, Y. Taniuchi
    JASRI/SPring-8, Hyogo-ken
  • T. Ohshima
    RIKEN/SPring-8, Hyogo
  • Z. R. Zhou
    USTC/NSRL, Hefei, Anhui
  We performed the storage of high current singlet of 10mA/bunch and a train of bunches of 0.3mA/bunch under the bunch by bunch feedback systems with newly developed bunch current sensitive automatic attenuators with FPGA. The automatic attenuator reduces the signal level of the high current bunch by factor three to five to avoid the saturation of the feedback systems. With this system, the feedback systems suppress horizontal and vertical mode-coupling instabilities and raise the bunch current limit from 3.5mA/bunch to 12mA/bunch, and simultaneously the systems suppress the multi-bunch instabilities by resistive-wall and cavity higher order mode impedances. The improvement of the automatic attenuation system to fit to the final target of the bunch current in the train, 0.06mA/bunch, are being performed. The other problems which limit the filling patterns, such as saturation of the readout electronics of the beam position monitor system and the heating of vacuum components by high current bunches, will be briefly presented.  
 
THPC128 Bunch by Bunch Feedback by RF Direct Sampling storage-ring, acceleration, controls, damping 3287
 
  • T. Nakamura, K. Kobayashi
    JASRI/SPring-8, Hyogo-ken
  • Z. R. Zhou
    USTC/NSRL, Hefei, Anhui
  Recent ADCs have wide analog band-width which is enough for direct sampling of the RF signal from a beam position monitor without down conversion. We employed such ADCs for our bunch-by-bunch signal processor* and performed the feedback with the direct RF sampling of the signal from a beam position monitor to detect the position of bunches. With RF direct sampling, the down conversion stage which is used in usual RF front-end circuits and is composed of mixers, filters, delays and base-band amplifiers is not necessary. This simplifies the systems, and reduces the costs and the number of the tuning parameters. The feedback system with RF direct sampling is now in operation at user mode in SPring-8.

*T. Nakamura, K. Kobayashi. "FPGA BASED BUNCH-BY-BUNCH FEEDBACK SIGNAL PROCESSOR", Proc. of ICALEPCS 05.

 
 
THPC130 Integrated Global Orbit Feedback with Slow and Fast Correctors power-supply, brilliance, emittance, storage-ring 3292
 
  • I. Pinayev
    BNL, Upton, New York
  The NSLS-II Light Source which is planned to be built at Brookhaven National Laboratory will provide users with ultra-bright synchrotron radiation sources and is designed for horizontal beam emittances <1 nm. Full utilization of the very small emittances and beam sizes requires sub-micron orbit stability in the storage ring. This can be provided by means of a wide bandwidth orbit feedback system. Traditional approach is to utilize a uniform set of fast correctors or use two separate systems with strong slow and weaker fast correctors. In the latter case two systems need to communicate to suppress transients associated with different update rates of corrector settings. In this paper we consider an integrated system with two types of correctors. Its main feature is that setpoints of slow correctors are updated with the same rate as fast correctors; however the bandwidth is limited in order to stay in linear regime. Possible architectures and technical solutions as well as achievable performance are discussed.  
 
THPC131 On the Optimal Number of Eigenvectors for Orbit Correction quadrupole, storage-ring, simulation, closed-orbit 3295
 
  • I. Pinayev, M. G. Fedurin
    BNL, Upton, New York
  The singular value decomposition method is widely used for orbit correction in the storage rings. It is a powerful tool for inverting of the usually rectangular response matrices, which usually have rectangular form. Another advantage is flexibility to choose number of eigenvectors for calculation of required strengths of orbit correctors. In particular, by reduction in number of eigenvectors one can average over ensemble noise in the beam position monitors. A theoretical approach as well as experimental results on the NSLS VUV ring are presented.  
 
THPC132 Bunch by bunch Transverse Feedback Development at ESRF kicker, damping, storage-ring, ion 3297
 
  • E. Plouviez, P. Arnoux, F. Epaud, J. M. Koch, G. A. Naylor, F. Uberto
    ESRF, Grenoble
  This paper describes the bunch by bunch transverse feedback implemented at ESRF. The first motivation of this project was to be able to cope with the constraint of the future operation of the ESRF with a stored current increased from 200mA to 300mA with a uniform or quasi uniform filling, but we were also interested in possible improvement of the operation with others filling patterns (16 and 4 bunches patterns for instance). Our system uses a classical scheme: The signal coming from a set of button type electrodes is demodulated in a homodyne RF front end and processed in a FPGA DSP to derive a correction signal which is applied to the beam with a wide band stripline kicker. Depending on the filling pattern of the storage ring (uniform filling or filling with a small number of high charge bunches), different kind of transverse instabilities have been observed in the past, due to the resistive wall impedance, ion trapping or mode coupling. We have tested the effect of our system in these different situation and report also the results of these tests.  
 
THPC133 Layout and Simulations of the FONT System at ATF2 kicker, extraction, simulation, pick-up 3300
 
  • J. Resta-López, P. Burrows
    JAI, Oxford
  We describe the adaptation of a Feedback On Nano-second Timescales (FONT) system for the final focus test beam line ATF2 at KEK. This system is located in the ATF2 extraction line, and is mainly conceived for cancellation of transverse jitter positions originated in the damping ring and by the extraction kickers. This jitter correction is performed by means of a combination of feed-forward (FF) and fast-feedback (FB) beam stabilisation. We define optimal positions for the kicker and BPM pairs of the FONT FF/FB system, and estimate the required kicker performance and BPM resolutions. Moreover simulation results are presented.  
 
THPC136 Design and Commissioning of a Bunch by Bunch Feedback System for the Australian Synchrotron kicker, damping, synchrotron, storage-ring 3306
 
  • M. J. Spencer, G. LeBlanc, K. Zingre
    ASP, Clayton, Victoria
  A transverse bunch feedback system has been designed in order to fight the effects of coupled bunch instabilities. This system is currently in the commissioning phase. A digital system was chosen because of its flexibility and diagnostic potential. While the major components were sourced from a private company, time has also been spent on in house development of an analogue front-end and the diagnostic components of the software.  
 
THPC138 Bunch-by-Bunch Online Diagnostics at HLS diagnostics, kicker, injection, storage-ring 3309
 
  • J. H. Wang, Y. B. Chen, L. J. Huang, W. Li, L. Liu, M. Meng, B. Sun, L. Wang, Y. L. Yang, Z. R. Zhou
    USTC/NSRL, Hefei, Anhui
  The design goal for the bunch-by-bunch analogue transverse feedback system at the Hefei Light Source (HLS) is to cure the transverse coupled bunch instabilities. The prototype implemented bunch-by-bunch feedback in 2006. Then we changed the circuit and replaced some components by ones of higher performance in order to get better effect. Diagnostic techniques are important tools to determine instabilities and to confirm the performance of the feedback systems. In addition to transverse feedback this system can provide online beam diagnostics and analysis in transverse and longitudinal directions. The diagnostic functions can record the response of every bunch while the feedback system manipulates the beam. The experimental results are presented.  
 
THPC139 Properties of X-ray Beam Position Monitors at the Swiss Light Source photon, vacuum, electron, controls 3312
 
  • T. Wehrli, M. Böge, J. Krempasky, E. D. van Garderen
    PSI, Villigen
  Tungsten blade type X-ray beam position monitors (X-BPMs) are widely used at the SLS to stabilize the photon beam position at the the micron level. Various slow (~0.5 Hz) photon beam position feedbacks (SPBPFs) being an integral part of the global orbit feedback system have been in operation for several years. They are solely based on one X-BPM reading assuming that the photon beam movement is dominated by angle changes of the electron beam. This paper reports on the operation of the first SPBPF using two X-BPMs. This allows the separation of positional and angular variations of the electron beam, which is of special importance for the recently commissioned PolLux dipole beamline, as it is mostly sensitive to position changes. Correlations between the electron beam movement and the X-BPM readings are extensively analyzed in order to disentangle systematic errors of the position determination and real orbit motion. Methods are presented on how to recognize and correct or even avoid large systematic errors of the X-BPMs. With this knowledge, the demanding requirements on X-BPM accuracy in case of a SPBPF utilizing two X-BPMs could be fulfilled for the first time at the SLS.  
 
THPC140 The Performance of a Fast Closed Orbit Feedback System with Combined Fast and Slow Correctors closed-orbit, power-supply, simulation, vacuum 3315
 
  • L.-H. Yu, S. Krinsky, O. Singh, F. J. Willeke
    BNL, Upton, Long Island, New York
  For NSLSII closed orbit feedback system, in order to reduce the noise caused by the step changes of the power supplies in the feedback system, the angular kick corresponding to the last bit of the power supplies for the fast correctors must be smaller than 3 nrad*. On the other hand, in order to carry out closed orbit alignment or orbit correction after a long term drift, we need strong correctors with 0.8 mrad kick strength*. In order to avoid the requirement of correctors with both large strength and very small minimum step size, we consider separate sets of slow correctors with large strength and fast correctors with smaller maximum strength. In order to avoid fast and slow feedback systems working in parallel, and avoid the possible interaction between two feedback systems, we consider the possibility of using only one fast feedback system with slow correctors periodically removing the DC components of the fast correctors so that the DC components in fast feedback system would not accumulate to reach saturation even after a large long term drift of the closed orbit motion. We report on simulation of the performance of this combined system for NSLSII in this paper.

* NSLSII Preliminary Design Report (2007)

 
 
THPC142 The Operation Event Logging System of the SLS controls, linac, beam-losses, radio-frequency 3318
 
  • A. Luedeke
    PSI, Villigen
  Modern 3rd generation synchrotron light sources aim for 100% availability. No single beam interruption is acceptable and every distortion of operation should be investigated: What caused the interruption? Can it be avoided in the future? If it can't be avoided, how can the recovery be accelerated? An automated event recording system has been implemented at the Swiss Light Source (SLS) in order to simplify this investigations. The system identifies distortions of the user operation and records automatically type and duration of the event. All relevant information connected to the event, from control system archive data to shift protocols, is linked to the event and presented in web pages. Additional information can be added manually. Each event will be assigned to a failure cause and area. Means to filter the events are provided. The paper will describe the concept and implementation of the even logging system at the SLS and the experiences with the system.  
 
THPC156 Performances of the SPARC Laser and RF Synchronization Systems laser, linac, klystron, radiation 3354
 
  • A. Gallo, D. Alesini, M. Bellaveglia, G. Gatti, C. Vicario
    INFN/LNF, Frascati (Roma)
  The SPARC project consists in a 150 MeV S-band, high-brilliance linac followed by 6 undulators for FEL radiation production at 530 nm. The linac assembly has been completed and the SPARC scientific program is presently in progress. The low level RF control electronics to monitor and synchronize the RF phase of the accelerating structures along the linac and the laser shot on the photocathode has been commissioned and it is now fully operative. The laser synchronization is routinely monitored and slow drifts are automatically corrected by a dedicated shot-to-shot feedback system. A similar slow automatic regulation is implemented on each linac accelerating section acting either on low level or high power sliding lines. The phase noise in the 2 RF power stations is counteracted by fast intra-pulse phase feedback systems that have been developed and put in operation. Phase stability measurements taken over the whole synchronization system are reported, and performances of different synchronization architectures, micro-wave based or laser based, are compared.  
 
THPC158 Measurement and Stabilization of the Bunch Arrival Time at FLASH laser, controls, electron, acceleration 3360
 
  • F. Loehl, V. R. Arsov, M. Felber, K. E. Hacker, B. Lorbeer, F. Ludwig, K.-H. Matthiesen, H. Schlarb, B. Schmidt
    DESY, Hamburg
  • W. Jalmuzna
    TUL-DMCS, Łódź
  • S. Schulz, A. Winter, J. Zemella
    Uni HH, Hamburg
  • J. Szewinski
    The Andrzej Soltan Institute for Nuclear Studies, Centre Swierk, Swierk/Otwock
  To fully exploit the experimental opportunities offered by the 10 - 30 fs long light pulses from FLASH, e.g. in pump-probe experiments, precise measurements and control of the electron-bunch arrival-time on the 10 fs scale are needed. A bunch arrival time monitor (BAM) which uses the optical synchronization system of FLASH as a reference has been developed for this purpose. The bunch induced signal from a GHz-bandwidth beam pick-up is guided into an electro-optical modulator in which the periodic laser pulse train of the optical synchronization system experiences an amplitude modulation. Detection of this modulation allows to determine the bunch arrival time with a resolution of better than 20 fs. The superconducting linac of FLASH generates trains of up to 800 bunches. The BAM signals can be used for an intra-bunch train feedback stabilizing the arrival time to better than 50 fs. The feedback is capable of generating well-defined arrival time patterns within a bunch train which are useful for overlap-scans in pump-probe experiments. First results from the feedback installed at FLASH will be presented.  
 
THPP047 Prototype of the High Voltage Section for the 2 MeV Electron Cooler at COSY electron, acceleration, controls, power-supply 3467
 
  • J. Dietrich
    FZJ, Jülich
  • M. I. Bryzgunov, A. D. Goncharov, V. V. Parkhomchuk, V. B. Reva, D. N. Skorobogatov
    BINP SB RAS, Novosibirsk
  The design, construction and installation of a 2 MeV electron cooling system for COSY-Juelich is proposed to further boost the luminosity even with strong heating effects of high-density internal targets. In addition the 2 MeV electron cooler for COSY is intended to test some new features of the high energy electron cooler for HESR at FAIR/GSI. The design of the 2 MeV electron cooler will be accomplished in cooperation with the Budker Institute of Nuclear Physics in Novosibirsk, Russia. The design and first experiments of a new developed prototype of the high voltage section, consisting of a gas turbine, magnetic coils and high voltage generator with electronics is reported.  
 
THPP060 Simultaneous Extraction of Two Stable Beams for ISAC extraction, cyclotron, target, resonance 3503
 
  • G. Dutto, R. A. Baartman, P. G. Bricault, I. V. Bylinskii, A. Hurst, R. E. Laxdal, Y.-N. Rao, L. W. Root, P. Schmor, G. M. Stinson
    TRIUMF, Vancouver
  • J. M. Schippers
    PSI, Villigen
  The TRIUMF cyclotron was originally conceived for several proton beams extracted simultaneously at different energies. Recent operation includes a 500 MeV beam up to150 μA for meson users, a 500 MeV beam up to 80 μA for rare isotope production, and a 100 MeV beam up to 70μA for medical isotopes. The extraction of an additional high intensity proton beam, at an energy between 450 and 500 MeV for ISAC has now been given priority. With the rare ions produced from the existing and future primary beam lines, we will be able to operate two of the existing experimental areas simultaneously. Upgrading the cyclotron for higher intensity is in progress. A necessary goal for ISAC is the extraction of both primary proton beams with stability better than 1% to allow the highest possible temperatures to be reliably maintained at the ion production targets. A successful solution implemented for the existing primary ISAC beam has been simulated to be adaptable for both primary beams, given the particular angular separation between the two strippers in the cyclotron. Progress on intensity and stability studies and the layout of the extraction system will be presented.  
 
THPP113 Emittance Growth at LHC Injection from SPS and LHC Kicker Ripple injection, kicker, emittance, damping 3629
 
  • B. Goddard, M. J. Barnes, L. Ducimetière, W. Höfle, G. Kotzian
    CERN, Geneva
  Fast pulsed kicker magnets are used to extract beams from the SPS and inject them into the LHC. The kickers exhibit time-varying structure in the pulse shape which translates into small offsets with respect to the closed orbit at LHC injection. The LHC damper systems will be used to damp out the resulting betatron oscillations, to keep the growth in the transverse emittance within specification. This paper describes the results of the measurements of the kicker ripple for the two systems, both in the laboratory and with beam, and presents the simulated performance of the transverse damper in terms of beam emittance growth. The implications for LHC operation are discussed.  
 
THPP114 LHC Transverse Feedback Damping Efficiency damping, injection, simulation, octupole 3632
 
  • G. Kotzian, W. Höfle
    CERN, Geneva
  • E. Vogel
    DESY, Hamburg
  A simulation model has been developed to predict the damping efficiency of the LHC transverse feedback system in the presence of coupled bunch instabilities and under realistic assumptions for the injection error. The model tracks both the centre of gravity of a bunch and the r.m.s beam size during and after injection. It includes the frequency characteristic of the transverse feedback system. Nonlinearities in the beam optics will cause the bunches to filament and lead to an increase of the transverse emittance after injection. The resistive wall instability reduces the effectiveness of the transverse feedback by slowing down the damping process. Possibilities for enhancing the performance of the feedback system by signal processing schemes are outlined.  
 
THPP123 Ramping Power Supplies for the SSRF Booster power-supply, controls, booster, dipole 3646
 
  • R. Li, H. G. Chen, D. M. Li, S. L. Lu, T. J. Shen, D. X. Wang
    SINAP, Shanghai
  The SSRF booster magnetic field ramped with a 250ms ramp, 2Hz cycle rate, and biased quasi-sinusoidal wave shape is successfully realized. Two Digital Switch-mode Power Supplies (DSPS) separately deliver currents to all dipoles, and other four DSPS deliver to the quadrupoles and sextupoles in families. Tracking precision and reducing line power fluctuation requirements are particularly challenging because of the fast ramp and high inductance load. In order to meet the requirements, the magnetic energy recycle, digital regulation and novel PID correction circuit are used. On Oct. 5th 2007, after a few days commissioning of the SSRF booster, the beam was boosted up to 3.5GeV firstly in SSRF, it proved that the design of ramping power supplies was correct and the manufacture was successful. The power supply system and its performance are described in this paper.  
 
THPP126 Four Quadrant 60 A, 8 V Power Converters for LHC radiation, dipole, controls, hadron 3655
 
  • L. Ceccone, V. Montabonnet
    CERN, Geneva
  The LHC (Large Hadron Collider) particle accelerator requires many true bipolar power converters (752), located under the accelerator dipole magnets in a radioactive environment. A special design and topology is required to obtain the necessary performance while meeting the criteria of radiation tolerance and compact size. This paper describes the ±60A ±8V power converter, designed by CERN to meet these requirements. Design aspects, performances and test results of this converter are presented.  
 
THPP134 Injection and Extraction DC Magnets Power Supplies for 3GeV Rapid Cycling Synchrotron of J-PARC power-supply, extraction, septum, injection 3676
 
  • M. Watanabe, J. Kamiya, M. Kinsho, T. Takayanagi, Y. Yamazaki, M. Yoshimoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • K. Hirano
    JAEA/LINAC, Ibaraki-ken
  • Y. Irie
    KEK, Ibaraki
  Proton beams have been successfully accelerated to the design energy of 3 GeV in the RCS at the J-PARC*. In the injection, dump and extraction sections of the RCS, septum magnets, a quadrupole magnet, dc kicker magnets and steering magnets have been installed and operated at DC. For the septum magnets, there is little space area available for the septum coil and a magnetic shield**. Therefore the power supplies are required high excitation current. Maximum currents of the injection and dump septum magnets are less than 7 kA. The extraction septum magnets need the maximum current of 12 kA***. For saving the cost and the installation space of the extraction septum magnets power supplies, a main power supply, which excites three extraction septum magnets in series, and three auxiliary power supplies for adjusting the current to the each magnet are employed. Long-term stability and the current ripples are required to be less than the order of 100 ppm for those power supplies in order to provide the required acceptance for the beams. This presentation shows design and measurements of the the injection and extraction DC power supplies.

*JAERI Technical Report 2003-044 and KEK Report 2002-13.
**M. Yoshimoto et al. Proc. of EPAC'06.
***M. Watanabe et al. IEEE Transactions on applied superconductivity, Vol.16, No.2, 2006.