A   B   C   D   E   F   G   H   I   K   L   M   O   P   Q   R   S   T   U   V   W    

controls

Paper Title Other Keywords Page
MOP015 Linac Design for the FERMI Project linac, laser, gun, electron 61
 
  • G. D'Auria, P. Craievich, P. Delgiusto, S. Di Mitri, M. Ferianis, E. Menotti, M. M. Milloch, G. C. Pappas, G. Penco, M. Trovo
    ELETTRA, Basovizza, Trieste
  • L. R. Doolittle, A. Ratti
    LBNL, Berkeley, California
  FERMI is a fourth generation light source under construction at Sincrotrone Trieste. This is based upon the conversion of the existing injector linac to a 1.2 GeV machine suitable to drive a seeded FEL. The linac will require significant improvements and the addition of several new accelerating modules. Important parameters are pulse to pulse energy stability and the jitter of the e-bunch time of arrival. This paper will cover the baseline design of the machine, as well as experimental results and the proposed technical solutions for the more critical sub-systems.  
 
MOP018 Upgrading the CEBAF Accelerator to 12 GeV: Project Status linac, beam-transport, acceleration, dipole 70
 
  • L. Harwood
    Jefferson Lab, Newport News, Virginia
  Jefferson Lab is preparing to upgrade its 6 GeV Continuous Electron Beam Accelerator Facility (CEBAF) to 12 GeV as part of the 12 GeV Upgrade project. The doubled energy will significantly extend the scientific reach of the three existing Halls with upgraded experimental equipment, and will make possible a new research program in exotic mesons in a newly constructed fourth Hall. The acceleration of the present linacs will be roughly doubled through the addition of ten new cryomodules with performance ~5 times the original specification for CEBAF. The 2K helium plant will be roughly doubled; new rf systems, including digital controls, will be installed for the new cryomodules. The beam transport system’s capability will be doubled by strongly leveraging existing hardware (without incurring significant saturation) but must be enhanced with some replacement magnets, new power supplies, one new recirculation arc, and a beamline to the new Hall. Critical Decision 1 was approved by DOE for this project in February 2006. Technical status for the accelerator systems including R&D will be presented as well as the status of the 12 GeV Upgrade Project as a whole.  
 
MOP019 Methods to Reduce the Electron Beam Energy Spread at the S-DALINAC electron, linac, recirculation, feedback 73
 
  • R. Eichhorn, A. Araz, U. Bonnes, M. Brunken, M. Gopych, H.-D. Gräf, S. Paret, M. Platz, A. Richter, S. Watzlawik
    TU Darmstadt, Darmstadt
  • W. F.O. Müller, B. Steiner, T. Weiland
    TEMF, Darmstadt
  The S-DALINAC is a recirculating superconducting electron linac operating at 3 GHz. The accelerator delivers a cw beam with energies up to 130 MeV to serve electron scattering experiments where highest momentum resolutions, typ. below 1·10-4 are required. Current activities aim to reduce the energy spread of the accelerator by two methods: Long term drifts, mainly a result of temperature drifts, will be corrected by a feedback system which measures the energy variation of the extracted beam continuously using rf-monitors. By means of time-of-flight analysis in a modified beamline a correction signal can be generated as a feedback for the rf control of the accelerating cavities. This system was set-up recently and first results will be reported. Furthermore, the influence of short term fluctuations, e.g. triggered by micro-phonics, on the electron energy can significantly be reduced utilizing the inherent stability of a microtron, if the synchronous phase and longitudinal dispersion are chosen properly. The concept, particle simulations and the experimental verification will be shown as well as necessary modifications to the recirculation scheme to use it in an all-day operation.  
 
MOP033 The Operation Concept of SARAF cryogenics, instrumentation, target, radiation 109
 
  • I. Mardor, D. Berkovits, Y. Grof, H. Hirshfeld, A. Nagler
    Soreq NRC, Yavne
  • O. Heber
    Weizmann Institute of Science, Physics, Rehovot
  • C. Piel
    ACCEL, Bergisch Gladbach
  The Soreq Applied Research Accelerator Facility (SARAF) is a 5 - 40 MeV, 0.04 -2 mA proton/deuteron RF superconducting linear accelerator, which is under construction at Soreq NRC and is planned to start generating a beam by the end of 2010. SARAF will be a multi-user facility, whose main activities will be neutron physics and applications, radio-pharmaceuticals development and production, and basic nuclear physics research. The operational concept of SARAF will be ‘one target at a time’ and during irradiation, appropriate shielding will enable preparation and maintenance at other stations. This paper presents the planned facility operation program, the planned operations group, the location and layout of the main control room and the architecture of the main control system, including its interfaces with safety and applications. Emphasis is given to the design considerations for each of the discussed subjects.  
 
MOP038 200-MHz, 1.5-MeV Deuteron RFQ Linac rfq, linac, ion, ion-source 124
 
  • D. A. Swenson, J. W. Starling
    Linac Systems, Albuquerque, New Mexico
  A 200-MHz, 1.5-MeV deuteron RFQ linac system is under construction at Linac Systems. The linac structure employs the four-bar, radial-strut design, where the four bars are supported by a series of radial struts emanating from the wall of a cylindrical cavity with four-pole symmetry. This structure looks and performs very much like the four-vane RFQ structure. This design is about twice the efficiency of the conventional four-bar RFQ design. Another important advantage of this design is that the dipole mode is higher in frequency than the quadrupole mode, thus eliminating any problems with the mixing of the dipole mode with the quadrupole mode. Injection of deuterons into the linac will be at 50 keV from a microwave ECR ion source. The linac structure is 2.72 meters long. The peak beam current out of the linac will be 20 mA. A pulse duty factor of 5% will yield an average beam current of 1 mA. The rf power requirement is 58 kW to excite the structure, plus 30 kW to accelerate the beam, for a total of 88 kW. This linac system is scheduled for completion in the spring of 2007.  
 
TUP001 Linac Automated Beam Phase Control System linac, klystron, gun, feedback 241
 
  • S. J. Pasky, M. Borland, L. Erwin, R. M. Lill, N. Sereno
    ANL, Argonne, Illinois
  Adjustment of the rf phase in a linear accelerator is crucial for maintaining optimal performance. If phasing is incorrect, the beam will in general have an energy error and increased energy spread. While an energy error can be readily detected and corrected using position readings from beam position monitors at dispersion locations, this is not helpful for correcting energy spread in a system with many possible phase errors. Uncorrected energy spread results in poor capture efficiency in downstream accelerators, such as the Advanced Photon Source (APS’s) Particle Accumulator Ring (PAR) or Booster synchrotron. To address this issue, APS has implemented beam-to-rf phase detectors in the linac, along with software for automatic correction of phase errors. We discuss the design, implementation, and performance of these detectors and how they improved APS top-up operations. * Work supported by U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38.  
 
TUP003 Spallation Neutron Source Linac Beam Position and Phase Monitor System linac, pick-up, SNS, instrumentation 247
 
  • J. F. Power, M. W. Stettler
    LANL, Los Alamos, New Mexico
  • A. V. Aleksandrov, S. Assadi, W. Blokland, P. Chu, C. Deibele, J. Galambos, C. D. Long, J. Pogge, A. Webster
    ORNL, Oak Ridge, Tennessee
  The SNS linac currently has 6x beam position monitors which allow the measurement of both beam position and phase from a single pickup. The signals from the pickup lobes are down converted from either 402.5MHz or 805 MHz to 50-MHz IF signals for processing. The IF signals are synchronously sampled at 40 MHz to generate I and Q signals from which the beam position and phase are calculated. Each BPM sampling reference frequency is locked to a phase-stable 2.5 MHz signal distributed along the linac. The system is continuously calibrated by generating and measuring rf bursts in the processor that travel to the BPM pickup, reflect off of the shorted BPM lobes and return to the processor for re-measurement. The electronics are built in a PCI card format and controlled vith LabVIEW. Details of the system design and performance are presented.  
 
TUP013 Using Higher Order Modes in Superconducting Accelerating Cavities for Beam Monitoring monitoring, dipole, single-bunch, electron 271
 
  • N. Baboi, O. Hensler
    DESY, Hamburg
  • N. E. Eddy, S. Nagaitsev
    Fermilab, Batavia, Illinois
  • J. C. Frisch, S. Molloy, M. C. Ross
    SLAC, Menlo Park, California
  • O. Napoly, R. Paparella
    CEA, Gif-sur-Yvette
  Dipole modes have been shown to be successful diagnostics for the beam position in superconducting accelerating cavities at the VUV Free Electron Laser (FEL) facility at DESY. By help of downmixing electronics the signals from the two higher order mode couplers mounted on each cavity are monitored. Due to the non-symmetric placement of the couplers and the overlapping of the two polarizations of the modes, the calibration is somewhat more complicated than in standard position monitors. A method based on the model independent analysis has been developed. The calibration measurements made at the VUV FEL will be presented.  
 
TUP016 BPM DAQ System Using Fast Digital Oscilloscope linac, feedback, injection, factory 280
 
  • M. Satoh, K. Furukawa, T. Suwada
    KEK, Ibaraki
  The KEK injector linac is planned to be upgraded to perform the simultaneous injection for four rings (KEKB e-/ e+, PF and PF-AR rings). In this operation mode, each rf pulse accelerates the beam with different charge and energy by controlling the low-level rf phase. For this purpose, it is strongly required to improve the BPM DAQ system. In the current system, maximum DAQ rate is strictly limited by the oscilloscope performance, and it should be improved for the 50-Hz measurement. We made decision to replace the current DAQ system by the fast digital oscilloscope. In this presentation, the system description of the new DAQ system and the result of the performance test will be presented.  
 
TUP017 A Damper System for the Electron Cooling Beam in the Recycler electron, damping, antiproton, feedback 283
 
  • P. Varghese, B. Chase, P. W. Joireman
    Fermilab, Batavia, Illinois
  The antiproton stacking rate in the Fermilab Recycler has been dramatically improved with the commissioning of the Electron Cooling system last year. Various disturbance sources such as mechanical vibrations in the Pelletron , power line fluctuations and coupling from beam ramps in the nearby Main Injector have added noise components in the electron beam position in the 0.5 to 200 Hz range. An AC coupled damping feedback loop with corrector coils for horizontal and vertical position correction at two upstream points from the BPMs was added to the existing BPM system . The system provides 10 – 20 dB damping in the frequency range above without interfering with other DC beam positioning control loops.  
 
TUP023 Beam-Size Measurements in the IPNS 50-MeV Transport Line Using Stripline BPMs linac, quadrupole, diagnostics, monitoring 296
 
  • J. C. Dooling, F. R. Brumwell, L. Donley, G. E. McMichael, V. F. Stipp
    ANL, Argonne, Illinois
  Continuing with the work started two years ago, the technique of using a two-beamlet model to measure beam size is presented. Beam signals are detected on terminated 50-ohm, stripline BPMs located in the transport line between the 50 MeV linac and rapid cycling synchrotron. Each BPM is constructed with four striplines: top, bottom, left and right. Using a fast-sampling oscilloscope to compare the signals from opposite strip lines allows one to determine beam size assuming a two beamlet model. Measurements made with the two-beamlet approach are compared with other standard profile diagnostics such as wire-scanners, segmented Faraday cups, and scintillators. Advantages of the two-beamlet method are that it is non intrusive and does not require the presence of a background gas necessary for an IPM. Disadvantages of the technique are that it does not provide a detailed profile and the longitudinal beam pulse length must be short relative to the stripline length.  
 
TUP029 Performance and Early Operating Experience with the ISAC-II Cryogenic System linac, cryogenics, vacuum, ion 306
 
  • R. E. Laxdal, W. Andersson, I. Sekachev, G. Stanford
    TRIUMF, Vancouver
  A 500 W class refrigerator has been installed and commissioned at TRIUMF to cool the new 20MV superconducting linac. The refrigerator liquifies helium into a common supply dewar. The dewar feeds a common cold manifold and the five cryomodules are fed via parallel cold distribution circuits. The system operates at 4.5K. Measurements have been done to estimate the static loads of the cryomodules and the distribution system and to characterize plant performance. The paper will include a system description, performance results and early operating experience.  
 
TUP030 RF Cavity Performance and RF Infrastructure for the ISAC-II Superconducting Linac linac, coupling, power-supply, acceleration 309
 
  • R. E. Laxdal, I. Bylinskii, K. Fong, M. P. Laverty, A. K. Mitra, T. C. Ries, Q. Zheng, V. Zviagintsev
    TRIUMF, Vancouver
  The ISAC-II superconducting linac is presently being commissioned. Twenty cavities have been prepared and characterized in single cavity tests before mounting in the on-line cryomodules. The cavities are specified to operate at a challenging peak surface field of 30MV to supply an accelerating voltage of 1.1MV/cavity. The cavity bandwidth of ±20Hz is achieved by overcoupling while a mechanical tuner actively maintains the cavity frequency within this bandwidth. An overview of the rf systems will be given. We will describe the early operating experience and compare the cavity on-line performance with the single cavity characterizations.  
 
TUP032 Comparison of SNS Superconducting Cavity Calibration Methods SNS, acceleration, beam-loading, pick-up 315
 
  • Y. Zhang, I. E. Campisi, P. Chu, J. Galambos, S. Henderson, D.-O. Jeon, K.-U. Kasemir, A. P. Shishlo
    ORNL, Oak Ridge, Tennessee
  Three different methods have been used to calibrate the SNS superconducting cavity RF field amplitude. Two are beam based and the other strictly RF based. One beam based method uses time-of-flight signature matching (phase scan method), and the other uses the beam-cavity interaction itself (drifting beam method). Both of these methods can be used to precisely calibrate the pickup probe of a SC cavity and determine the synchronous phase. The initial comparisons of the beam based techniques at SNS did not achieve the desired precision of 1% due to the influence of calibration errors, noise and coherent interfaces in the system. To date the beam-based SC cavity pickup probe calibrations agree within approximately 4%, comparable to the conventional RF calibrations.  
 
TUP064 Adaptive Three-Dimensional RMS Envelope Simulation in the SAD Accelerator Modeling Environment space-charge, simulation, optics, background 397
 
  • C. K. Allen
    LANL, Los Alamos, New Mexico
  • K. Furukawa, M. Ikegami, K. Oide
    KEK, Ibaraki
  The capability for three-dimensional RMS envelope simulation, including space charge, has been implemented in the SAD accelerator modeling environment used at KEK. The SAD (for Strategic Accelerator Design) modeling system consists of a compiled simulation engine, an in-house scripting language SADScript, and user interface support both in Tcl/tk script and SADScript. The RMS envelope simulator is implemented primarily in the SADScript language, which much resembles the Mathematica language. The dynamics within the model are similar to that used by TRACE3D, TRANSPORT, and XAL. Specifically, the symmetric matrix of all second-order beam moments is propagated using a linear beam optics model for the beamline. However, the current simulation engine employs an adaptive space-charge algorithm which actively adjusts the solution integration to maintain a specified accuracy, as well as imposing the symplectic condition. It is designed to keep the integration step size as large as possible while enforcing that the residual solution error remain below a given tolerance. The paper concentrates primarily on the adaptive nature of the RMS simulation, since this is the novel feature.  
 
TUP077 Transverse Beam Matching and Correction Procedures in INR Linac linac, quadrupole, simulation, focusing 435
 
  • S. Bragin, A. Feschenko, O. V. Grekhov, N. F. Lebedeva, V. N. Mikhailov, A. N. Mirzojan, V. A. Moiseev, O. Volodkevich
    RAS/INR, Moscow
  An interactive procedure for the transverse beam matching and correction has been developed and implemented in several areas of INR Linac. The profile measurements are used for determination of the main transverse beam parameters. These data are applied for calculation the dipole correction currents and quadrupole gradients to transport the beam with minimum sizes and off axis displacements. The user friendly interface and graphics support has been developed for data treatment and beam behavior presentation. The proposed algorithm of beam matching, beam steering and data treatment is discussed. Some experimental and simulation results for different INR Linac operation modes are presented.  
 
TUP083 Development of High-Power RF Vector Modulator Employing TEM Ferrite Phase Shifters SNS, impedance, linac, vacuum 451
 
  • Y. W. Kang, M. S. Champion, S.-H. Kim, M. P. McCarthy, A. V. Vassioutchenko, J. L. Wilson
    ORNL, Oak Ridge, Tennessee
  Construction and installation of cavity RF power distribution system in a high power superconducting RF accelerator can have cost savings if a fan-out configuration that feeds many cavities with a single high power klystron is realized. The configuration however requires independent control of RF amplitudes and phases to the cavities to perform properly. A prototype high power RF vector modulator for the control is built and tested. The vector modulator employs a quadrature hybrid and two fast ferrite phase shifters in square coaxial TEM transmission lines. The square coaxial format can provide the power handling capability and thermal stability. RF properties of the design and result of high power system testing of the design are presented.  
 
TUP084 Drifting Beam Application for SNS Superconducting Cavity Setting SNS, linac, beam-loading, Spallation-Neutron-Source 454
 
  • P. Chu, Y. Zhang
    ORNL, Oak Ridge, Tennessee
  A software application for tuning superconducting linac cavity has been developed and tested at the Spallation Neutron Source (SNS). The application is based on the drifting beam method and the XAL online model. The drifting beam method and the application were proved to be consistent with other cavity tuning method during the SNS commissioning runs. Detail algorithm and data acquisition for the application will be presented.  
 
WE2003 LLRF Systems for Modern Linacs: Design and Performance feedback, linac, resonance, coupling 498
 
  • A. Brandt
    DESY, Hamburg
  Near-future linac projects put yet unreached requirements on the LLRF control hardware in both performance and manageability. Meeting their field stability targets requires a clear identification of all critical items along the LLRF control loop as well as knowledge of fundamental limitations. Large-scale systems demand for extended automation concepts. The experience gained with present systems as well as dedicated experiments deliver the basis for a design of future systems. Digital hardware has evolved quickly over the past years and FPGAs became common not only in LLRF control. A high degree of digitization in various fields, as for example beam diagnostics, suggests to aim for a convergence of the digital platform designs. Channeling of efforts of different research laboratories may be the key to an affordable solution that meets all requirements and has a broad range of applications.  
 
TH1002 Cryomodule Test Facilities and Multicell Cavity Performance for the ILC linac, linear-collider, klystron, superconducting-RF 516
 
  • H. Hayano
    KEK, Ibaraki
  To address the ILC Main Linac gradient, which are greater than 35MV/m at vertical test and greater than 31.5MV/m in the operation of the cryomodule, ILC-GDE organized several task forces in the R&D board. They are S0 task force, S1 task force, and S2 task force. The charge of S0 is to achieve 35MV/m in the qualification with reasonable yield. S1 is to achieve 31.5MV/m operation of cryomodule. And S2 is to estimate how large test facility is required to test chain of cryomodules and to make industrialization of cryomodule production. The paper reports the task force activities status together with existing R&D of multicell cavity performance and cryomodule test facility status.  
 
THP001 Conceptual LLRF Design for the European X-FEL feedback, diagnostics, klystron, resonance 559
 
  • S. Simrock, V. Ayvazyan, A. Brandt, M. Huening, W. Koprek, F. Ludwig, K. Rehlich, E. Vogel, H. C. Weddig
    DESY, Hamburg
  • M. K. Grecki, T. Jezynski
    TUL-DMCS, Lodz
  • W. J. Jalmuzna
    Warsaw University of Technology, Institute of Electronic Systems, Warsaw
  The LLRF System for the superconducting cavities of the European X-FEL must support an amplitude and phase stability of the accelerating fields of up to 0.01% and 0.01 deg. respectively. The stability must be achieved in pulsed operation with one klystron driving 32 cavities. This goal can only be achieved with low noise downconverters for field detection, high gain feedback loops and sophisticated feedforward techniques. State-of-the art technology including analog multipliers for downconversion, fast ADCs (>100 MHz) with high resolution (up to 16 bit), and high performance data processing with FPGAs with low latency (few hundred ns) allow to meets these goals. The large number of input channels ( >100 including probe, forward and reflected signal of each of the 32 cavities) and output channels (>34 including piezo tuners for each cavity) combined with the tremendous processing power requires a distributed architecture using Gigalink interfaces for low latency data exchange.  
 
THP002 Exception Detection and Handling for Digital RF Control Systems klystron, linac, radiation, feedback 562
 
  • S. Simrock, V. Ayvazyan, M. G. Hoffmann, M. Huening, W. Koprek, K. Rehlich, E. Vogel
    DESY, Hamburg
  Exception detection and handling routines will play an important role in future large scale accelerator to ensure high availability and beam stability in presence of interlock trips, varying operational parameters, and operation close to the performance limit. For superconducting linacs typical examples for exception situations include cavity quenches, coupler and klystron gun sparcs, operation close to klystron saturation, and errors in vector-sum calibration. The goal is to identify all possible exception situations which will lead to performance degradation or downtime, detect these situations and take appropriate actions as necessary.  
 
THP003 Integrated Optical Timing and RF Reference Distribution System for Large-Scale Linear Accelerators laser, feedback, electron, linac 565
 
  • A. Winter, J. Becker, F. Loehl, K. Rehlich, S. Simrock
    DESY, Hamburg
  Highly-stable timing and RF reference distribution systems are required to meet the tight specifications in large scale accelerators for next generation light sources. In this paper, we present an approach based on the distribution of an optical pulse train from a mode-locked laser via timing stabilized fiber links. The timing information is contained in the precise repetition rate of the optical pulse train (~50 MHz), so RF can be extracted at end stations with a stability on the order of 10 fs. Less timing critical signals such as ADC clocks and trigger signals can be transmitted through the same stabilized fiber using a modulated cw laser operating at a different wavelength with sub-ps stability. As multiple wavelengths can propagate without interference through the fiber, it is also possible to integrate data communication in such a fiber system. This paper will review the timing system requirements and present a conceptual layout of an optical timing and reference frequency distribution system based on work done at MIT and DESY for the XFEL.  
 
THP004 Digital Low-Level RF Control Using Non-IQ Sampling feedback, SNS, linac, rfq 568
 
  • L. R. Doolittle
    LBNL, Berkeley, California
  • M. S. Champion, H. Ma
    ORNL, Oak Ridge, Tennessee
  The success of digital feedback with synchronous IQ sampling for cavity field control in recent accelerator projects make this LLRF control scheme a popular choice. This short-period synchronous sampling does not, however, average out well-known defects in modern ADC and DAC hardware. That limits the achievable control precision for digital IQ LLRF controllers, while demands for precision are increasing for future accelerators such as International Linear Collider. For this reason, a collaborative effort is developing a digital LLRF control evaluation platform to experiment using coherent sampling with much longer synchronous periods, on the order of the cavity closed-loop bandwidth. This exercise will develop and test the hardware and software needed to meet greater future RF control challenges.  
 
THP005 Digital Control of Cavity Fields in the Spallation Neutron Source Superconducting Linac linac, SNS, feedback, beam-loading 571
 
  • H. Ma, M. S. Champion, M. T. Crofford, K.-U. Kasemir, M. F. Piller
    ORNL, Oak Ridge, Tennessee
  • A. Brandt
    DESY, Hamburg
  • L. R. Doolittle, A. Ratti
    LBNL, Berkeley, California
  Control of the pulsed RF cavity fields in the Spallation Neutron Source (SNS) superconducting Linac uses both the real-time feedback regulation and the pulse-to-pulse adaptive feed-forward compensation. This control combination is required to deal with the typical issues associated with superconducting cavities, such as the Lorentz force detuning, mechanical resonance modes, and cavity filling. The all-digital implementation of this system provides the capabilities and flexibility necessary for achieving the required performance, and to accommodate the needs of various control schemes. The low-latency design of the digital hardware has successfully produced a wide control bandwidth, and the developed adaptive feed forward algorithms have proved to be essential for the controlled cavity filling, the suppression of the cavity mechanical resonances, and the beam loading compensation. As of this time, all 96 LLRF systems throughout the Linac have been commissioned and are in operation.  
 
THP006 Performance of a Digital LLRF Field Control System for the J-PARC Linac beam-loading, feedback, linac, klystron 574
 
  • S. Michizono, S. Anami, Z. Fang, S. Yamaguchi
    KEK, Ibaraki
  • T. Kobayashi
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • H. Suzuki
    JAEA, Ibaraki-ken
  Twenty high power klystrons are installed in the J-PARC linac. The requirements for the rf field stabilities are ±1% in amplitude and ±1 deg. in phase during a 500 us flat-top. In order to satisfy these requirements, we adopt the digital feedback and feed-forward system with FPGAs and a commercial DSP board. The FPGAs (Virtex-II 2000) enable a fast PI control for a vector sum of two cavity fields. The measured stability during rf pulse was ±0.15% in amplitude and ±0.15 deg in phase. The tuner control was successively operated by a way of the DSP board by measuring the phase difference between the cavity input wave and the cavity field. Beam loading effects were emulated using a beam-loading test box. By proper feed-forward, the rf stability was less than ±0.3% and ±.15 deg.  
 
THP007 Timing Distribution in Accelerators via Stabilized Optical Fiber Links laser, feedback, pick-up, linac 577
 
  • J. M. Byrd, L. R. Doolittle, A. Ratti, J. W. Staples, R. B. Wilcox
    LBNL, Berkeley, California
  We present progress on fiber-optic based systems for highly stable distribution of timing signals for accelerators. This system has application for linac-based sources of ultrafast radiation which require sub-100 fsec synchronization or for very large accelerators such as the linear collider. The system is based on optical fiber links that are stabilized with an optical interferometer with RF and timing signals distributed as modulations on the optical carrier. We present measurements of the stability of this link over distances of several hundred meters and discuss issues for testing the link over 10 km.  
 
THP009 Performance of RF Reference Distribution System for the J-PARC Linac linac, klystron, feedback, injection 583
 
  • T. Kobayashi
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • S. Anami, S. Michizono, S. Yamaguchi
    KEK, Ibaraki
  • E. Chishiro
    JAEA, Ibaraki-ken
  Installation of the J-PARC linac machines (Phase I) has been almost completed and the beam commissioning will be started in December this year. The error of the accelerating field must be within ±1 degree in phase and ±1% in amplitude. Thus, high phase stability is required as an RF reference. Our objective concerning the phase stability of the reference aims at less than ±0.3 degrees. Last year the installation of the RF reference distribution system was completed. The reference signal is optically distributed to all of the low-level RF control systems by using E/O, O/E, Optical Amplifier and Optical Couplers and so on. The performance of this system was evaluated. The phase stability of ±0.06 degrees was obtained.  
 
THP010 Low-level RF system for STF klystron, feedback, linac, superconducting-RF 586
 
  • T. Matsumoto, S. Fukuda, H. Katagiri, S. Michizono, Y. Yano
    KEK, Ibaraki
  • Z. Geng
    IHEP Beijing, Beijing
  The Super-conducting RF Test Facility (STF) has been constructed to establish the production technique of a cavity having a high gradient and operated for the high power testing of the klystron and couplers being installed in the superconducting cavities. An accelerating electric field stability of 0.3% (rms) in amplitude and 0.3 degree (rms) in phase is also required for the RF system in STF. In order to satisfy these requirements, a digital LLRF control system using FPGA is adopted, and the components required for the digital LLRF system have been developed.  
 
THP011 High Gradient Operation with the CEBAF Upgrade RF Control System resonance, feedback, linac, electron 589
 
  • C. Hovater, G. K. Davis, H. Dong, A. S. Hofler, K. King, J. Musson, T. E. Plawski
    Jefferson Lab, Newport News, Virginia
  The CEBAF Accelerator at Jefferson Lab is presently a 6 GeV five pass electron accelerator consisting of two superconducting linacs joined by independent magnetic transport arcs. It is planned to increase the energy to 12 GeV with the addition of 10 new high gradient cryomodules (17+ MV/m). The higher gradients pose significant challenges beyond what the present analog low level RF (LLRF) control systems can handle reliably; therefore, a new LLRF control system is needed. A prototype system has been developed incorporating a large FPGA and using digital down and up conversion to minimize the need for analog components. The new system is more flexible and less susceptible to drifts and component nonlinearities. Because resonance control is critical to reach high gradients quickly, the new cryomodules will include a piezoelectric tuner for each cavity, and the LLRF controls must incorporate both feedback and feed-forward methods to achieve optimal resonance control performance. This paper discusses development of the new RF system, system performance for phase and amplitude stability and resonance control under Lorentz detuning measured during recent tests on a prototype cryomodule.  
 
THP012 Adaptive Tuner Control in TRIUMF ISAC 2 Superconducting LINAC using Kalman Filter feedback, linac, superconducting-RF, pick-up 592
 
  • K. Fong, M. P. Laverty, Q. Zheng
    TRIUMF, Vancouver
  The TRIUMF ISAC 2 RF control system uses phase locking self-excited control. Amplitude, phase and frequency control is achieved with I/Q voltage injection, and forward RF power is minimized with a tuner feedback loop. The phase difference between the input coupler and the output pickup drives a velocity servo system to provide tuning control. However, the presence of microphonics in the cryomodule, although under control by the Quadrature loop, still presents a noisy interference on the phase difference for the tuner. The tuner will follow this noise and generate more microphonics as a result. A first-order Kalman filter is used for an estimation of the phase difference and reduces the movement of the tuner.  
 
THP013 Adaptive Control of a SC Cavity Based on the Physical Parameters Identification klystron, feedback, radio-frequency, resonance 595
 
  • T. Czarski, W. J. Jalmuzna, W. Koprek, K. T. Pozniak, R. S. Romaniuk
    Warsaw University of Technology, Institute of Electronic Systems, Warsaw
  • S. Simrock
    DESY, Hamburg
  The paper presents preliminary results of SRF cavity control by FPGA system called "SIMCON". Algebraic model of the control system including calibration and correction procedure of the signal path was discussed. In particular, there were debated the following aspects of the automatic control procedures: compensation of the input offset, calibration of the cavity channel and correction of the klystron channel (linearization). Functional structure of FPGA based SIMCON board for LLRF Cavity Control System was explained. Alghoritm of adaptive control for cavity driven with FPGA controller supported by MATLAB system was discussed. Experimental results for 8 cavities of ACC1 module controlled by the SIMCON board were shown. The resuls lead to novel method of parameters identification of cavity system in noisy and no stationary conditions.  
 
THP016 Active Compensation of Lorentz Force Detuning of a TTF 9-Cell Cavity in CRYHOLAB simulation, klystron, feedback, radiation 598
 
  • G. Devanz, P. Bosland, M. Desmons, E. Jacques, M. Luong, B. Visentin
    CEA, Gif-sur-Yvette
  • M. Fouaidy
    IPN, Orsay
  Linear colliders and free-electron lasers projects based on the superconducting RF technology require high gradient pulsed operation of superconducting elliptical multicells. The cavities are subject to Lorentz force detuning which reflects on an increased RF power consumption when trying to stabilize the accelerating field during the beam passage. This pulsed detuning can be mechanically compensated using a fast piezoelectric tuner. A new tuner with integrated piezoelectric actuators has been developed in the framework of CARE/SRF european program. The tuning system has been tested on a fully equipped 9-cell TTF cavity in the CRYHOLAB horizontal cryostat using the pulsed 1.3 GHz 1 MW RF source. In virtue of the high pulse to pulse repeatability of the detuning, the compensation of Lorentz detuning was achieved successfully using a simple feed forward scheme.  
 
THP017 Magnet Hysteresis Control at LANSCE power-supply, quadrupole, linac, acceleration 601
 
  • R. C. McCrady, R. Keller
    LANL, Los Alamos, New Mexico
  We have investigated the effects of magnet hysteresis in various beamlines at LANSCE (Los Alamos Neutron Science Center) and have developed procedures to control the effects. Particular challenges are presented by sets of magnets with parallel boosting and bucking windings on the same yoke powered by two families of supplies and by magnets whose fields are routinely reversed for different operating modes. The results of the procedures are more rapid recovery from power-off conditions and rapid switching between operating modes, with minimized re-tuning. The latter improvement has been beneficial in controlling a beam instability that has adverse effects on the users’ experiments.  
 
THP019 Commissioning of the Digital LLRF for the CEBAF Injector/Separator feedback, insertion, linac, instrumentation 607
 
  • T. E. Plawski, H. Dong, C. Hovater, K. King, G. E. Lahti, J. Musson
    Jefferson Lab, Newport News, Virginia
  The design and production of the CEBAF accelerator 499 MHz digital Low-Level RF control system has been completed. The first five systems were installed for use with the CEBAF Separator RF deflecting cavities operating at 499 MHz. The next four systems were installed in the injector on the chopping cavities (also 499 MHz deflecting cavities). The new LLRF system replaced an analog system that was over 15 years old. For initial testing an extensive acceptance plan along with a LLRF test stand was developed and incorporated to assure system performance as well as reliability. Various VHDL firmware was developed and modified to support operation of this system and included specific operational diagnostics. Once the acceptance tests were completed, the new systems were installed in the accelerator, in parallel with the existing analog LLRF, for extensive in-situ testing and comparison. After system commissioning, the new RF systems were assigned to the CEBAF accelerator and turned over to Accelerator Operations. This paper will address the VHDL firmware evolution, the automated tests and the performance measurements made through out the installation and commissioning process.  
 
THP022 Status of RF Sources in Super-Conducting RF Test Facility (STF) at KEK klystron, superconducting-RF, acceleration, linac 613
 
  • S. Fukuda, M. Akemoto, H. Hayano, H. Katagiri, S. Kazakov, S. Matsumoto, T. Matsumoto, S. Michizono, H. Nakajima, K. Nakao, T. Shidara, T. Takenaka, Y. Yano, M. Yoshida
    KEK, Ibaraki
  Super-conducting rf test facility (STF) has been progessing in KEK since 2005. In this paper, we describe the current status of rf sources in STF. STF rf sources comprise of a long pulse modulator with bouncer circuit, a pulse transformer, an L-band 5MW klystron, power distribution system and low level rf system. We have completed the construction of the first rf system and have been testing for the system evaluation and for the coupler test of the super-conducting cavity. We have a schedule to feed a power to the cryomodule with 8 super-conducting cavities in December of 2006. We also describe the plan of the second rf sources of STF.  
 
THP023 Status of and Future Plan for the NSRL Microwave Power System linac, klystron, power-supply, radiation 616
 
  • L. Shang
    USTC/NSRL, Hefei, Anhui
  In this paper, 20MW microwave power system for NSRL (National synchrotron radiation Laboratory) Linac is introduced. The power system includes five s-band 20MW klystrons and their modulators. In 2002, the klystron modulators and the control system were upgraded. Constant-current, switching power supplies were employed to replace the old conventional LC resonant charging facilities. The new system has run for four years and played an important role in the operation of the 200MeV LINAC. A new soft x-ray FEL project (HTF) is now proposed in NSRL, the energy of electron beam will be increase from 200MeV to 800MeV. Seven s-band 80 MW klystrons and modulators will be employed as the new microwave power sources. The low energy spread specification of the Linac sets a stringent requirement to the stability of the klystron modulators. The paper also presents the technical considerations and preliminary design of the new system  
 
THP025 R&D of the Long-Life Thyratron Tube cathode, collider, feedback, pick-up 622
 
  • H. Matsumoto
    KEK, Ibaraki
  • J.-S. Oh
    PAL, Pohang, Kyungbuk
  Long lifetime over 50k hours for the thyratron is essential to provide the reasonable availability of the accelerator such as X-FEL and future e+e- linear collider. The lifetime and reliability of a solid-state device are not well confirmed yet. There are some examples that show long life of a thyratron. Many thyratrons were dead due to several common causes related to circuits and operation environment rather than intrinsic problems of a device itself. Several valuable feedback systems are easily adopted to enhance the lifetime. There are still unidentified questions to be verified in the thyratron. Close collaboration between laboratories and companies is strongly requested in order to improve the lifetime and performance of a thyratron.  
 
THP028 Master Oscillator for Fermilab ILC Test Accelerator simulation, power-supply, resonance, linear-collider 631
 
  • J. Branlard, B. Chase, E. Cullerton
    Fermilab, Batavia, Illinois
  The low phase-noise master oscillator generates and distributes the various frequencies required for the LLRF system controlling ILCTA cavities. Two chassis have been developed for this design, generating the programmable frequencies and performing the distribution and amplification, respectively. It has been successfully used with the SNS and the DESY-SIMCON LLRF systems, driving two different superconducting cavities. The design approach and a full characterization of the master oscillator are presented in this paper. The measurement results include the frequency stability and the phase and amplitude noise spectrums of the multiple frequency outputs.  
 
THP039 Status of the RF Systems for the SPIRAL2 Linac at the Beginning of the Construction Phase rfq, ion, linac, diagnostics 664
 
  • M. Di Giacomo, B. Ducoudret, M. Tripon
    GANIL, Caen
  • P. De Antoni, P. Galdemard, M. Luong, O. Piquet
    CEA, Gif-sur-Yvette
  The Spiral 2 project uses an RFQ and a superconductiong linac to accelerate high intensity beams of deuterons and heavier ions. The accelatoror frequency is 88 MHz. The construction phase was approved in Mai 2005 and the project organization was recently finalized. The RF Systems activity includes power amplifiers and control electronics for all the accelerator and some of the RF devices on the beam line: the slow and fast chopper and the rebunchers. The paper describes the status of the amplifiers prototypes, the architecture chosen for the digital LLRF and the preliminary studies on the other RF devices.  
 
THP043 The RF System of the Sparc Photo-Injector @ LNF klystron, gun, linac, vacuum 676
 
  • R. Boni, D. Alesini, M. Bellaveglia, A. Clozza, G. Di Pirro, A. Gallo, L. Palumbo, B. Spataro, F. Tazzioli, C. Vaccarezza, M. Vescovi
    INFN/LNF, Frascati (Roma)
  The S-band linear accelerator SPARC is in advanced phase of installation and test at the INFN Frascati Laboratories. The purpose of the machine is to produce low emittance, high peak current electron beams to drive a SASE-FEL experiment. The SPARC RF system consists of an RF gun followed by 3 S-band room-temperature accelerating structures, supplied by 2 pulsed high power klystrons. The use of waveguide power attenuators and phase-shifters is foreseen to adjust independently the accelerating structures field amplitude and phase; this will be helpful for tuning the linac working point in the initial machine set-up. This paper reviews the experience in installation, RF conditioning, and commissioning of the normal conducting linac accelerating structures and RF subsystems.  
 
THP051 Status of 3.9-GHz Superconducting RF Cavity Technology at Fermilab superconducting-RF, vacuum, linac, higher-order-mode 695
 
  • H. Edwards, T. T. Arkan, H. Carter, C. A. Cooper, M. Foley, E. R. Harms, T. K. Khabiboulline, D. V. Mitchell, D. O. Olis, A. M. Rowe, N. Solyak, S. Tariq
    Fermilab, Batavia, Illinois
  Fermilab is involved in an effort to design, build, test and deliver 3.9 GHz superconducting RF cavities with a goal to deliver one 'third harmonic' cryomodule containing four cavities in early 2007 for use at the DESY TTF III Project. The design gradient of these cavities is 19 MV/m. This effort involves design, fabrication, intermediate testing, assembly, and eventual delivery of the four cavity cryomodule. We report on all facets of this enterprise from design through future plans. Included will be early test results of single 9-cell cavities, lessons learned, and other findings.  
 
THP052 Tests Results of Beta 0.12 Quarter-Wave Resonator for the SPIRAL2 Superconducting Linac linac, cryogenics, heavy-ion, vacuum 698
 
  • G. Olry, S. Blivet, S. Bousson, T. Junquera, J. Lesrel, fl. Lutton, G. Martinet, H. Saugnac
    IPN, Orsay
  New developments and tests have been carried out, at IPN-Orsay, on high β = 0.12, 88 MHz superconducting Quarter Wave Resonators. These resonators will be installed in the high beta section of the LINAC driver. RF tests results of the prototype cavity are reported. The fabrication of 2 pre-series cavities and their cryomodule is in progress in order to be ready for high power RF tests at 4.2 K at the beginning of 2007.  
 
THP075 RF Performance of a Superconducting S-Band Cavity Filled with Liquid Helium vacuum, pick-up, superconductivity, radiation 755
 
  • W. Hartung, J. Bierwagen, S. Bricker, C. Compton, T. L. Grimm, M. J. Johnson, D. Meidlinger, D. Pendell, J. Popielarski, L. Saxton, R. C. York
    NSCL, East Lansing, Michigan
  Copper RF cavities filled with hydrogen gas at high pressure have been studied recently by Muons, Inc. and IIT for simultaneous acceleration and ionisation cooling of a muon beam. A further step in this direction would be a superconducting RF cavity filled with liquid helium. One might imagine that this would make the cavity less vulnerable to thermal breakdown, field emission, and multipacting. A disadvantage is that magnetostatic focussing of the beam could not be done simultaneously. Preliminary RF testing has been done on a 2.45 GHz single-cell elliptical cavity filled with liquid helium. Low-field results indicate little or no increase in the power dissipation, consistent with predictions and measurements in the literature. The frequency shift with pressure for a cavity filled with saturated liquid is about 100 times greater than for a cavity under vacuum, consistent with published values of liquid helium permittivity as a function of temperature. Investigation of the high-field performance of a liquid-filled cavity is in progress.  
 
THP082 Industrialization of TESLA-Type SRF Technology at ACCEL vacuum, cryogenics, electron, monitoring 773
 
  • M. Pekeler, S. Bauer, H. Vogel, P. vom Stein
    ACCEL, Bergisch Gladbach
  In the last 15 years the worldwide TESLA collaboration under the leadership of DESY performed successful developements of SRF technology for possible use in a future international linear collider (ILC). Today this technology is also the baseline for other demanding projects like the European X-FEL at DESY site, 4GLS at Daresbury, BESSY FEL, Cornell-ERL, FEL at Peking University and others. Through all these years ACCEL has followed and supported this tremendous developement by producing and processing SRF cavities, couplers and complete accelerator modules. The current ability and future prospects of ACCEL for manufacturing and processing such key components as well as turnkey SRF modules with guaranteed performance for such projects are described.  
 
THP086 Mitigation of Power Loss Due to Skin Effect by Thin-Layered Film resonance, vacuum, electromagnetic-fields 785
 
  • Y. Iwashita
    Kyoto ICR, Uji, Kyoto
  The AC current flows only on the metal surface, which is known as skin effect. The current concentration on the surface increases power loss. This results higher transmission loss of cable and degradation of Q in cavities. Skin effect on a metal film that is thinner than a skin depth is investigated starting from general derivation of skin depth on a bulk conductor. The reduction of the skin effect power loss with layered conductor films is reported and discussed.  
 
THP092 Control System for a Limitation of an Integrated Amount of Beam Charges Delivered from the KEKB Injector Linac injection, linac, electron, positron 800
 
  • T. Suwada, K. Furukawa, E. Kadokura, M. Satoh
    KEK, Ibaraki
  A new control system is under construction for radiation safety at the KEKB injector linac. The control system restricts the integrated amount of the beam charges delivered from an electron gun in order to keep the radiation safety with high reliability in a daily operation of the linac. The old control system of the radiation safety has been working based on a software control implemented on a UNIX-based workstation. However, this control system is not possible to be implemented for the long-term linac operation with high reliability. The new control system comprises a charge-integration-type analog circuit mounted along with a CPU chip and a data acquisition system based on programmable logic controllers. The fast analog circuit can detect the beam-charge signals delivered from a wall-current monitor, and control the beam-abort trigger pulses pulse-by-pulse. The new hardware-based control system may stabilize the radiation safety control for the long-term linac operation. In this report the design of the new control system is described along with preliminary test results.  
 
THP097 FPGA BASED DIGITAL RF CONTROL FOR FLASH klystron, feedback, gun, cathode 809
 
  • W. J. Jalmuzna, P. F. Fafara, W. Koprek, P. K. Perkuszewski, K. T. Pozniak, P. Pucyk, R. S. Romaniuk
    Warsaw University of Technology, Institute of Electronic Systems, Warsaw
  • S. Simrock
    DESY, Hamburg
  Most parts of the LLRF control system used in FLASH are based on the DSP processors. Actual computation power of the system is close to the limit, the algorithm is performed in a time longer than 1μs. The only way to extend the system with new features was to add more DSP processors. This solution requires integration of new DSP board into existing system. It may cause some additional problems and delays in the machine operations. During past years very fast progress on the FPGA market was observed. Nowadays FPGA chips have reached the computation power that can be compared with DSP processors. These chips offer variety of the embedded solutions such as PowerPC, Microblaze, Nios which can be easily used in addition to fast, parallel signal processing. Moreover large number of user pins makes it possible to integrate all the elements necessary for the control into one PCB board. Therefore, for the evaluation purposes, some parts of the system were replaced by FPGA based boards. This article summarizes the FPGA boards that are currently in use and describes algorithms executed by these boards.  
 
FR1004 Recent Developments in SRF Cavity Science and Performance superconductivity, linear-collider, collider, cathode 818
 
  • G. Ciovati
    Jefferson Lab, Newport News, Virginia
  The performances of SRF cavities made of high purity bulk niobium have been improving in the last few years and surface magnetic fields (Bp) close to the thermodynamic critical field of niobium have been achieved in a few cases. The recommendation made in 2004 in favor of SRF as the technology of choice for the International Linear Collider (ILC), requires to improve the reliability of multi-cell cavities operating at accelerating gradients (Eacc) of the order of 35 MV/m . Additionally, a better understanding of the present limitations to cavity performance, such as the high-field Q-drop is needed. This contribution presents some recent developments in SRF cavity science and performance. Among the most significant advances of the last few years, new cavity shapes with lower ratio Bp/Eacc were designed and tested. Cavities made of large-grain niobium became available, promising lower cost at comparable performance to standard fine-grain ones and several tests on single-cell cavities were done to gain a better understanding of high-field losses. In addition, studies to improve the reliability of electropolishing are being carried out by several research groups.