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klystron

 
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MOPCH004 Coherent Harmonic Generation Experiment on UVSOR-II Storage Ring laser, electron, storage-ring, undulator 50
 
  • M. Labat
    CEA, Gif-sur-Yvette
  • M.-E. Couprie
    SOLEIL, Gif-sur-Yvette
  • T. Hara
    RIKEN Spring-8 Harima, Hyogo
  • M. Hosaka, M. Katoh, A. Mochihashi, M. Shimada, J. Yamazaki
    UVSOR, Okazaki
  • G. Lambert
    RIKEN Spring-8, Hyogo
  • D. Nutarelli
    LAC, Orsay
  • Y. Takashima
    Nagoya University, Nagoya
  Harmonic Generation schemes on Free Electron Laser devices are very promising. The injection of a traditional laser source inside the first undulator leads to an efficient energy modulation of the electron bunch, and therefore, its spatial modulation, resulting in a more coherent light emission along the second undulator. Experiments have been performed on the UVSOR-II Storage Ring at Okazaki (Japan) with electrons stored at an energy of 600 MeV, and using a 2.5 mJ Ti:Sa laser at 800 nm wavelength, 1 kHz repetition rate, and 100 fs up to 2 ps pulse duration. The experimental setup is presented, including the transport alignment and synchronisation between the laser and the electron beam. The third harmonic at 266 nm has been characterised versus various parameters: current, RF cavity voltage, undulator gap, magnetic functions of the storage ring, and laser pulse duration. Those results are compared with theory via analytical models and simulations.  
 
MOPCH010 High Power Tests of a High Duty Cycle, High Repetition Rate RF Photoinjector Gun for the BESSY FEL gun, DESY, PITZ, FEL 68
 
  • F. Marhauser
    BESSY GmbH, Berlin
  The proposed BESSY Soft X-ray FEL uses a normal conducting 1.3 GHz photoinjector RF gun cavity at comissioning phase. Due to the challenging RF pulse pattern the cavity has to cope with an average power of 75 kW. A 1.5-cell RF gun prototype has been built with a dedicated cooling layout. Results of the first high power RF tests are detailed in this paper.  
 
MOPCH140 Compensation of Lorentz Force Detuning of a TTF 9-cell Cavity with a New Integrated Piezo Tuner TTF, controls, feedback, resonance 378
 
  • G. Devanz, P. Bosland, M. Desmons, E. Jacques, M. Luong, B. Visentin
    CEA, Gif-sur-Yvette
  The high gradient operation of superconducting elliptical multicells in pulsed mode is required for linear colliders or free-electron lasers based on the superconducting technology. Such an operation is limited by dynamic Lorentz force detuning if no compensation for this effect is attempted. The RF power headroom required for accelerating field amplitude and phase stabilisation by low-level RF control techniques solely would be too costly. A new active tuner with integrated piezo actuators has been developped in the framework of the european CARE/SRF program solve this issue. The design is based on the lever-arm concept of the Saclay tuner already installed on running TTF cavities. We have carried out integrated tests of the 9-cell cavity equipped with the piezo tuner and power coupler in the CryHoLab horizontal test cryostat. Characterisation of the electromechanical system consisting of the cavity and piezo-tuner assembly and full power pulsed tests will be presented.  
 
MOPCH149 Microphonics Measurements in a CW-driven TESLA-type Cavity resonance, cryogenics, pick-up, linac 405
 
  • O. Kugeler, W. Anders, J. Knobloch, A. Neumann
    BESSY GmbH, Berlin
  Superconducting cavities with a high quality factor exhibit a very low bandwidth in their resonant frequency, which makes their operation very sensitive to mechanical oscillations. In CW mode of operation, as is intended for the BESSY-FEL Linac, microphonics are therefore the dominant error source for field stability. In order to compensate the detuning, it is necessary to properly characterize amplitude and frequency with respect to all involved mechanical and electrical components. Such measurements have been performed at the HoBiCaT test facility at BESSY and will be described in detail.  
 
MOPCH151 Pulsed RF System for the ELBE Superconducting Accelerator ELBE, controls, DESY, vacuum 411
 
  • A. Buechner, F.G. Gabriel
    FZR/FWFE, Dresden
  • H. Buettig, U. Lehnert, P. Michel, Ch. Schneider, R. Schurig
    FZR, Dresden
  The RF system for the ELBE accelerator was originally designed for CW mode. Although this works problem-free tests have shown that it is possible to reach higher gradients in the TESLA cavities with a pulsed RF system. The new RF system will be presented together with measurements of the achievable gradients. Roughly 30% higher gradients could now be used in pulsed mode. As positive side effects the radiation by field emission is reduced by the duty cycle and an easy in situ RF conditioning of cavities and coupler windows is possible.  
 
MOPCH175 High Power Testing RF System Components for the Cornell ERL Injector ERL, coupling, linac, factory 472
 
  • S.A. Belomestnykh, R.P.K. Kaplan, M. Liepe, P. Quigley, J.J.R. Reilly, C.K. Sinclair, V. Veshcherevich
    Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York
  There are two high power 1300 MHz RF systms under development for the Cornell University ERL Injector. The first system, based on a 16 kWCW IOT transmitter, will provide RF power to a buncher cavity. The second system employs five 120 kWCW klystrons to feed 2-cell superconducting cavities of the injector cryomodule. All components of these systems were ordered and some have already been delivered, including the IOT transmitter (manufactured by Thales-BM), 20 kWCW AFT circulator, 170 kWCW circulators (Ferrite Co.) and two prototype input couplers for superconducting cavities. A special LN2 cryostat has been designed and built for testing/processing the input couplers. The results of the first high-power tests are presented.  
 
MOPCH181 1.3 GHz Electrically-controlled Fast Ferroelectric Tuner coupling, TESLA, controls, feedback 487
 
  • V.P. Yakovlev
    Omega-P, Inc., New Haven, Connecticut
  • J.L. Hirshfield
    Yale University, Physics Department, New Haven, CT
  • S. Kazakov
    KEK, Ibaraki
  A fast, electrically-controlled tuner is described with parameters suitable for operation with the 9-cell SC accelerator structure of ILC. The tuner is based on a magic tee and two phase shifters that contain ferroelectric rings. The dielectric constant of the ferroelectric ring is altered by applying a 4.2 kV DC pulse that provides an RF phase shift from 0 deg to 180 deg. This, in turn allows a change of the input signal amplitude from zero to its maximum value, or a change in phase from 0 deg to 360 deg during the RF pulse. It is shown that the possibility of changing the cavity coupling to the input line during the RF pulse allows significant RF power savings, up to 12.5 MW for the 800 GeV ILC option. In addition, fast electrically-tuned amplitude and phase control with a feed-back system should be useful to compensate for possible phase deviations of the input RF fields in each cavity of ILC to match the cavity with the feeding transmission line as the beam load varies.  
 
MOPLS065 An ILC Main Linac Simulation Package Based on Merlin simulation, linac, emittance, alignment 694
 
  • N.J. Walker, D. Kruecker, F. Poirier
    DESY, Hamburg
  The preservation of the ultra-small vertical emittance in the International Linear Collider (ILC) will require the use of beam-based alignment techniques, the expected performance of which relies heavily on the use of simulation tools. In this report, we present the newest release of a purpose-built ILC main linac simulation tool, based on the Merlin* C++ class library. Examples of results from Dispersion Free Steering (DFS) simulations are also be presented.

*http://www.desy.de/~merlin

 
 
MOPLS099 A Study of Failure Modes in the ILC Main Linac quadrupole, linac, simulation, lattice 789
 
  • D. Schulte, P. Eliasson, A. Latina
    CERN, Geneva
  • Eckhard. Elsen, D. Kruecker, F. Poirier, N.J. Walker, G.X. Xia
    DESY, Hamburg
  Failures in the ILC can lead to beam loss or even damage the machine. Also failures that do not lead to beam loss can affect the luminosity performance, in particular since some time is required to recover from them. In the paper a number of different failures is being investigated and the impact on the machine performance is being studied.  
 
MOPLS110 ILC Linac R&D at SLAC SLAC, linac, DESY, collider 822
 
  • C. Adolphsen
    SLAC, Menlo Park, California
  Since the ITRP recommendation in 2004 to use superconducting rf technology for a next generation linear collider, the former NLC group at SLAC has been actively pursuing a broad range of R&D for this collider (the ILC). In this paper, we review the progress of those programs relating to linac technology. These include the development of a Marx-style modulator (120 kV, 120 A, 1.5 ms, 5 Hz) and a 10 MW sheet-beam klystron, construction of an L-band (1.3 GHz) rf source using a SNS HVCM modulator and commercial klystrons, fabrication and testing of a five-cell L-band cavity prototype for the ILC positron capture accelerator, high power tests of cavity coupler components, beam tests of prototype S-band linac beam position monitors and measurements of the magnetic center stability of an ILC prototype superconducting quadrupole magnet built by the CIEMAT group in Spain.  
 
MOPLS116 Status Report on the Harmonic Double-sided Microtron of MAMI C linac, dipole, MAMI, vacuum 834
 
  • A. Jankowiak, K. Aulenbacher, O. Chubarov, M. Dehn, H. Euteneuer, F.F. Fichtner, F. Hagenbuck, R.H. Herr, P. Jennewein, K.-H. Kaiser, W.K. Klag, H.J. Kreidel, U.L. Ludwig-Mertin, J.R. Röthgen, S.S. Schumann, G.S. Stephan, V. Tioukine
    IKP, Mainz
  The Mainz Mikrotron MAMI is a cascade of three racetrack microtrons, delivering since 1991 a high quality 855MeV, 100muA cw electron beam for nuclear and radiation physics experiments. An energy upgrade of this machine to 1.5GeV by adding a Harmonic Double-Sided Microtron (HDSM)* as a fourth stage is well under way. Here we give a review of the experiences gained during fabrication and testing of the main components of the HDSM and report the status of its construction. Initial operation of the machine is expected for the first half of 2006. After a period of commissioning in diagnostic pulse mode with low beam power (10ns, high intensity bunch trains with a repetition rate of max. 10kHz), soon the first nuclear physics experiments will be started.

*A. Jankowiak et al. "Design and Status of the 1.5 GeV-Harmonic Double Sided Microtron for MAMI", Proceedings EPAC2002, Paris, p. 1085.

 
 
TUPCH116 Waveguide Distribution Systems for the European XFEL XFEL, DESY, linac, coupling 1286
 
  • V.V. Katalev, S. Choroba
    DESY, Hamburg
  In the European X-ray FEL 32 superconducting cavities are connected to a 10 MW multibeam klystron through a waveguide distribution system. The basic waveguide system is a linear system. The XFEL tunnel has limited space for the waveguide system and therefore some new compact high power waveguide components like a motor driven phaseshifter, an iris tuner and an asymmetric shunt tee have been developed. Also alternative layouts of the waveguide distribution system which may have certain advantages have been designed. In this report we will present the different layouts and report on the status of the development of the different new waveguide components.  
 
TUPCH121 The IASA Cooling System for the 10 MeV Linac controls, linac, microtron, resonance 1298
 
  • A. Karabarbounis, D. Baltadoros, T. Garetsos, C.N. Papanicolas, E. Stiliaris
    IASA, Athens
  • A. Zolfaghari
    MIT, Middleton, Massachusetts
  A de-ionized water cooling system for the IASA room temperature 10 MeV CW Linac has been constructed and successfully installed. Commissioning is undergoing achieving resistivity larger to 5M?cm with a temperature accuracy of for all three linacs. Three ways mixing valves with a stepping capability of one thousand different mixing steps fulfill independently for each section the required temperature stability and the appropriate resonance frequency to our cavities. The RF requirements for the three linacs is 190kW provided by a single high power klystron tube capable to deliver up to 500 kW CW at 2380 MHz. The klystron is been cooled with a parallel similar cooling system and a third system cools our Aluminum waveguide complex. In this paper we will present the design, specifications and results of our preliminary tests. A sophisticated control and interlock system based on EPICS guarantees the proper functioning of the system.  
 
TUPCH134 RF Characteristics of the PEFP DTL coupling, controls, rfq, proton 1331
 
  • H. S. Kim, Y.-S. Cho, H.-J. Kwon, K.T. Seol
    KAERI, Daejon
  A conventional 20 MeV Drift Tube Linac (DTL) for the Proton Engineering Frontier Project (PEFP) has been developed as a low energy section of a 100 MeV accelerator. The 20 MeV DTL consists of 4 tanks with 152 cells. The machine has a unique feature of driving the 4 tanks with a single klystron. Therefore it has several control knobs to compensate the errors of each tank during operation. To develop the RF control scheme, the variations of the RF parameters of each tank were measured under various environmental conditions such as wall temperature, cooling water temperature, and cooling water pressure. In addition, the behaviors of the RF parameters among the tanks were also monitored during high power operation. In this paper, the measurement results are discussed and the control scheme based on the results are proposed.  
 
TUPCH136 Phase Measurement and Compensation System in PLS 2.5 GeV Linac for PAL-XFEL linac, feedback, XFEL, electron 1337
 
  • W.H. Hwang, J. Choi, Y.J. Han, J.Y. Huang, H.-G. Kim, S.-C. Kim, I.S. Ko, W.W. Lee
    PAL, Pohang, Kyungbuk
  In PAL, We are preparing the 3.7 GeV PALXFEL project by upgrading the present 2.5GeV Linac. In present PLS Linac, the specifications of the beam energy spread and rf phase are 0.6%(peak) and 3.5 degrees(peak) respectively. And the output power of klystron is 80 MW at the pulse width of 4 ? and the repetition rate of 10 Hz. In XFEL, the specifications of the beam energy spread and rf phase are 0.03%(rms) and 0.01 degrees(rms) respectively. We developed an analogue and a digital phase measurement and rf phase compensation system for stable beam quality. This paper describes the microwave system for the PALXFEL and the rf phase measurement and phase compensation system.  
 
TUPCH141 New Developments for the RF System of the ALBA Storage Ring simulation, storage-ring, synchrotron, insertion 1346
 
  • F. Pérez, B. B. Baricevic, D. Einfeld, H. Hassanzadegan, A. Salom, P. Sanchez
    ALBA, Bellaterra
  ALBA is a 3 GeV, 400 mA, 3rd generation Synchrotron Light Source that is in the construction phase in Cerdanyola, Spain. The RF System will have to provide 3.6 MV of accelerating voltage and restore up to 540 kW of power to the electron beam. For that six RF plants, working at 500 MHz, are foreseen. The RF plants will include several new developments: 1) DAMPY cavity: the normal conducting HOM damped cavity developed by BESSY and based in the EU design; six will be installed. 2) CaCo: A cavity combiner to add the power to two 80 kW IOTs to produce the 160 kW needed for each cavity. 3) WATRAX: A waveguide transition to coaxial, specially designed to feed the DAMPY cavities due to the geometrical and cooling constrains. 4) IQ LLRF: The low level RF will be based on the IQ modulation/demodulation technique, both analogue and digital approach are being pursued. This paper describes the Storage Ring RF System and reports about the status of these new developments.  
 
TUPCH144 Automatic Conditioning of the CTF3 RF System vacuum, CTF3, controls, CERN 1355
 
  • J.P.H. Sladen, S. Deghaye, S. Livesley, J. Marques Balula, J. Mourier, J.-M. Nonglaton
    CERN, Geneva
  • A. Dubrovsky
    JINR, Dubna, Moscow Region
  The RF system of CTF3 (CLIC Test Facility 3) includes ten 35 MW to 40 MW 3 GHz klystrons and one 20 MW 1.5 GHz klystron. High power RF conditioning of the waveguide network and cavities connected to each klystron can be extremely time consuming. Because of this, a fully automatic conditioning system has been developed within a CERN JINR (Dubna) collaboration. It involves relatively minor hardware additions, most of the work being in application and front-end software. The system has already been used very successfully.  
 
TUPCH147 High Pressure RF Cavities in Magnetic Fields pick-up, vacuum, ion, resonance 1364
 
  • P.M. Hanlet, M. Alsharo'a, R. E. Hartline, R.P. Johnson, M. Kuchnir, K. Paul
    Muons, Inc, Batavia
  • C.M. Ankenbrandt, A. Moretti, M. Popovic
    Fermilab, Batavia, Illinois
  • D.M. Kaplan, K. Yonehara
    Illinois Institute of Technology, Chicago, Illinois
  A study of RF breakdown in pressurized cavities immersed in strong magnetic fields has begun as part of a program to develop RF cavities filled with dense hydrogen gas to be used for muon ionization cooling. A pressurized 805 MHz test cell is being used at Fermilab to compare the conditioning and breakdown behavior of copper, molybdenum, and beryllium electrodes as functions of hydrogen and helium gas densities and magnetic field strength. These results will be compared to the predicted or known RF breakdown behavior of these metals in vacuum with and without external magnetic fields.  
 
TUPCH150 Improved 1.3 GHz Inductive Output Tube for Particle Accelerators synchrotron, ERLP, linac 1373
 
  • A.E. Wheelhouse
    e2v technologies, Chelmsford, Essex
  There is an increasing requirement for RF power sources in the L-band frequency range for operation in particle accelerators. Previously (at PAC 2005), the design, development and initial testing of a new L-band 16kW cw inductive output tube (IOT) was described. This paper discusses the detailed performance characteristics of the latest EEV IOT116LS embodying the most recent design improvements and presents data demonstrating its suitability for operation at 1.3GHz in the next generation of light sources.  
 
TUPCH153 IOT Testing at the ERLP ERLP, power-supply, controls, DIAMOND 1382
 
  • J.F. Orrett, S.R. Buckley, P.A. Corlett, A.J. Moss
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • S. Rains
    Diamond, Oxfordshire
  The testing of Inductive Output Tubes (IOT) at 1.3GHz is underway for use on the Energy Recovery Linac Prototype (ERLP) being constructed at Daresbury Laboratory. A 50KV high voltage power supply (HVPS) has been commissioned and characterised for use as a test RF supply. This will be used to power the ERLP RF system in both continuous and pulse modes of operation. First results are presented of the IOTs and the use of the HVPS system.  
 
TUPCH159 High Power Waveguide Switching System for SPring-8 Linac linac, vacuum, injection, electron 1397
 
  • T. Taniuchi, T. Asaka, H. Dewa, H. Hanaki, T. Kobayashi, A. Mizuno, S. Suzuki, H. Tomizawa, K. Yanagida
    JASRI/SPring-8, Hyogo-ken
  • A. Miura
    Nihon Koshuha Co., Ltd., Yokohama
  A vacuum waveguide switch has been developed to build a backup system of an RF source for the electron injector system and the klystron drive line in the SPring-8 linac. A high power test of the waveguide switch was carried out, and the maximum RF power of 62 MW in peak, 1μsecond in pulse width and 10 pps in repetition rate was achieved without serious problems in RF and vacuum characteristics. The backup system utilizing this waveguide switch has been installed in the electron injector system.  
 
TUPCH160 Novel Conception of Beam Temperature in Accelerator and Applications electron, emittance 1400
 
  • D. Dong
    IHEP Beijing, Beijing
  In this paper, we will introduce a novel conception of beam temperature in accelerator, discuss the calculation method. And finally the author will show an example on the beam temperature in a klystron.  
 
TUPCH162 Operation Results of 1 MW RF Systems for the PEFP 20 MeV Linac rfq, power-supply, proton, linac 1402
 
  • K.T. Seol, Y.-S. Cho, H. S. Kim, H.-J. Kwon
    KAERI, Daejon
  • K.R. Kim
    PAL, Pohang, Kyungbuk
  The PEFP 20 MeV linear accelerator is composed of a 3 MeV RFQ and 20 MeV DTL. Two sets of 1MW, 350MHz RF systems drive the RFQ and DTL. The RF system can perform a 100% duty operation. The TH2089F klystron is used as an RF source. During the test operation, only the driving RF signal of the klystron was operated in pulse mode, while the electron beam was maintained in DC mode. The klystron power supplies and cooling systems were also operated in 100% duty mode. In this paper, the operation results of 1 MW RF systems including klystron power supply and cooling system are discussed and propose possible options to improve the operation conditions based on the results.  
 
TUPCH166 Multi-megawatt Harmonic Multiplier for Testing High-gradient Accelerator Structures SLAC, gun, electron, simulation 1414
 
  • V.P. Yakovlev
    Omega-P, Inc., New Haven, Connecticut
  • J.L. Hirshfield
    Yale University, Physics Department, New Haven, CT
  Basic studies for determining the RF electric and magnetic field limits on surfaces of materials suitable for accelerator structures for a future multi-TeV collider, and for the testing of the accelerator structures and components themselves, require stand-alone high-power RF sources at several frequencies, from 10 to 45 GHz. A relatively simple and inexpensive two-cavity harmonic multiplier at 22.8, 34.3, or 45.7 GHz is suggested to be the stand-alone multi-MW RF power source for this application. The design is based on the use of an existing SLAC electron gun, such as the XP3 gun, plus a beam collector as used on the XP3 klystron. RF drive power would be supplied from an 11.4 GHz, 50 or 75 MW SLAC klystron and modulator, and a second modulator would be used to power the gun in the multiplier. Preliminary computations show that 64, 55, and 47 MW, respectively, can be realized in 2nd, 3rd, and 4th harmonic multipliers at 22.8, 34.3, and 45.7 GHz using 75 MW of X-band drive power.  
 
TUPCH188 Phase Stability of the Next Generation RF Field Control for VUV- and X-ray Free Electron Laser electron, controls, free-electron-laser, laser 1453
 
  • F. Ludwig, M. Hoffmann, H. Schlarb, S. Simrock
    DESY, Hamburg
  For pump and probe experiments at VUV- and X-ray free electron lasers the stability of the electron beam and timing reference must be guaranteed in phase for the injector and bunch compression section within a resolution of 0.01 degree (rms) and in amplitude within 1 10-4 (rms). The performance of the field detection and regulation of the acceleration RF directly influences the phase and amplitude stability. In this paper we present the phase noise budget for a RF-regulation system including the noise characterization of all subcomponents, in detail down-converter, ADC sampling, vector-modulator, master oscillator and klystron. We study the amplitude to phase noise conversion for a detuned cavity. In addition we investigate the beam jitter induced by these noise sources within the regulation and determine the optimal controller gain. We acknowledge financial support by DESY Hamburg and the EUROFEL project.  
 
TUPCH190 Universal Controller for Digital RF Control controls, resonance, beam-loading, feedback 1459
 
  • S. Simrock
    DESY, Hamburg
  • W. Cichalewski, M.K. Grecki, G.W. Jablonski
    TUL-DMCS, Lodz
  • W.J. Jalmuzna
    Warsaw University of Technology, Institute of Electronic Systems, Warsaw
  Digital RF control systems allow to change the type of controller by programming of the algorithms executed in FPGAs and/or DSPs. It is even possible to design a universal controller where the controller mode is selected by change of parameters. The concept of a universal controller includes the self-excited-loop (SEL) and generator driven resonator (GDR) concept, the choice of I/Q and amplitude or phase control, and allows for different filters (including Kalman filter and method of optimal controller synthesis) to be applied. Even time-varying mixtures of these modes are possible. Presented is the implementation of such a controller and the operational results with a superconducting cavity.  
 
TUPCH195 The LHC Low Level RF feedback, controls, LHC, injection 1471
 
  • P. Baudrenghien, G. Hagmann, J.C. Molendijk, R. Olsen, A. Rohlev, V. Rossi, D. Stellfeld, D. Valuch, U. Wehrle
    CERN, Geneva
  The LHC RF consists in eight 400 MHz superconducting cavities per ring, with each cavity independently powered by a 300 kW klystron, via a circulator. The challenge for the Low Level is to cope with both very high beam current (more than 1A RF component) and excellent beam lifetime (emittance growth time in excess of 25 hours). For each cavity we have a Cavity Controller rack with two VME crates implementing a strong RF Feedback, a Tuner Loop with a new algorithm, a Klystron Ripple Loop and a Conditioning system. In addition each ring has a Beam Control system (four VME crates) including Frequency Program, Phase Loop, Radial Loop and Synchronization Loop. A Longitudinal Damper (dipole and quadrupole mode) acting via the 400 MHz cavities is included to reduce emittance blow-up due to filamentation following phase and energy errors at injection. Finally an RF Synchronization system implements the bunch into bucket transfer from the SPS into each LHC ring. When fully installed in 2007 the whole system will count over three hundreds home-designed VME cards of twenty-three different models installed in fourty-five VME crates.  
 
TUPCH197 Low level RF System Development for the Superconducting Cavity in NSRRC controls, feedback, FIR, linac 1477
 
  • M.-S. Yeh, L.-H. Chang, F.-T. Chung, K.-T. Hsu, Y.-H. Lin, C. Wang
    NSRRC, Hsinchu
  The present low level system in NSRRC is based on analogy feedback control scheme. It provides feedback regulation on EM field, phase, and resonant frequency of the superconducting RF cavity. In order to address the required flexibility and improve diagnostic of the RF control system, a new digital low-level RF system based on Field Programmable Gate Array (FPGA) is proposed to be develop in house. The status of current analogy low level RF system and the specification of new digital FPGA based low level RF system are reposted herein.  
 
TUPCH200 Amplitude Linearizers for PEP-II 1.2 MW Klystrons and LLRF Systems controls, feedback, impedance, power-supply 1480
 
  • D. Van Winkle, J. Browne, J.D. Fox, T. Mastorides, C.H. Rivetta, D. Teytelman
    SLAC, Menlo Park, California
  The PEP-II B-factory has aggressive current increases planned for luminosity through 2008. At 2.2 A (HER) on 4 A (LER) currents, longitudinal growth rates will exceed the damping rates achievable in the existing low level RF and longitudinal low mode feedback systems. Klystron gain non-linearity has been shown to be a key contributor to these increased growth rates through time domain non-linear modeling and machine measurements. Four prototype klystron amplitude modulation linearizers have been developed to explore improved linearity in the LLRF system. The linearizers operate at 475 MHz with 15 dB dynamic range and 1 MHz linear control bandwidth. Results from lab measurements and high current beam tests are presented. Future development progress and production designs are detailed.  
 
TUPLS051 Development of PEFP 20 MeV Proton Accelerator proton, rfq, ion-source, site 1609
 
  • Y.-S. Cho, H.M. Choi, S.-H. Han, I.-S. Hong, J.-H. Jang, H. S. Kim, K.Y. Kim, Y.-H. Kim, H.-J. Kwon, K.T. Seol, Y.-G. Song
    KAERI, Daejon
  A 20 MeV proton accelerator has been developed as a low energy part of PEFP (Proton Engineering Frontier Project) 100 MeV accelerator. The 20 MeV accelerator consists of ion source, LEBT (Low Energy Beam Transport), 3 MeV RFQ (Radiofrequency Quadrupole) and 20 MeV DTL (Drift Tube Linac). After the field tuning and high power RF conditioning of the accelerating cavities, the first beam test of the 20 MeV accelerator is underway. During the test, the pulsed proton beam was extracted from the ion source by pulsing the high voltage power supply. Two 1.1 MW, 350MHz RF systems were used to drive the 20 MeV accelerator. The current transformers between DTL tanks and Faraday cup at the end of 20 MeV DTL were used to measure the beam current. In this paper, the development of 20MeV accelerator are summarized and the first beam test results are discussed.  
 
WEXPA02 New Developments on RF Power Sources storage-ring, DIAMOND, linac, ESRF 1842
 
  • J. Jacob
    ESRF, Grenoble
  The classical generation of RF power with klystrons and tetrodes is evolving and changing to meet the demands of higher efficiency and simpler maintenance. Developments of IOT tubes for FEL, Energy Recovery Linacs and Storage Rings, together with solid state technology approaches and combination techniques for high power generation are opening new alternatives to the classical ones. An overview of the new concepts, designs and solutions applied to the new accelerators will be presented. Advantages and drawbacks of new versus classical technologies as well as strategies for the selection will be discussed.  
slides icon Transparencies
 
WEPLS020 The RF Deflector for the CTF3 Delay Loop CTF3, linac, vacuum, coupling 2436
 
  • F. Marcellini, D. Alesini
    INFN/LNF, Frascati (Roma)
  In the CLIC Test Facility 3 (CTF3) a 42 m long ring, called delay loop, is used to halve the distance between bunches in the drive beam. The compression is obtained by merging two adjacent bunch trains from the linac deflected in opposite directions by an RF device, in such a way that the first train is forced to perform a full revolution in the delay loop, while the second one passes through. The length of the ring is an odd multiple of half the distance between bunches in the beam from the linac. The RF deflector consists of two identical cavities connected to the RF power source through a hybrid junction that equally splits the power and isolates the klystron from reflections. Its innovative design, the results of electromagnetic simulations and expected performances are described, together with low level RF measurements for test and characterization of the device before installation. Preliminary recombination results with the CTF3 beam are also shown. The RF deflector has also been used to measure the length of the accelerated bunches.  
 
WEPLS122 Multiphase Resonant Power Converter for High Energy Physics Applications controls, power-supply, radio-frequency, feedback 2658
 
  • M.J. Bland, J. Clare, P. W. Wheeler
    University of Nottingham, Nottingham
  Accelerators used for experiments in high-energy physics require very high power radio frequency sources to provide the energy needed to accelerate the particles. The RF power needs to be stable and predictable such that any variation in the supplied RF power has a limited and acceptable impact on the accelerated beam quality. This paper considers the design of a "long-pulse" modulator supply rated at 25kV, 10A (250kW peak power, duty ratio 10%, 25kW average power, pulse length ≈ 1 − 2ms). The supply is based on direct modulation of a multi-phase resonant power supply, fed by an active rectifier. The objectives of the development are to produce a compact power supply, with low stored energy and with high power quality at the utility supply. The paper provides a brief overview of the technology, followed by a discussion of the design choices. Initial results from the laboratory prototype will be included.  
 
WEPLS138 Operation Status and Statistics of the KEK Electron/Positron Linac linac, KEKB, positron, injection 2700
 
  • Y. Ogawa, A. Enomoto, K. Furukawa, T. Kamitani, M. Satoh, T. Sugimura, T. Suwada, Y. Yano, K. Yokoyama, M. Yoshida
    KEK, Ibaraki
  • Y. Imai, T. Kudou, S. Kusano, K. Suzuki, T. Toufuku
    MELCO SC, Tsukuba
  The KEK electron/positron linac has been operated since 1982, surpassing the total operation time of more than 100,000 hours. It delivers four different beams to four different rings quite stably, even frequently switching beam modes. The operation time per year has reached 7,000 hours since 1999 when the KEKB entered a normal operation mode. Operation status and statistics will be reported with the emphasis on continuing efforts in various kinds of machine improvements, which have ensured the stable operation.  
 
WEPLS139 Operational Status of Klystron-modulator System for PAL 2.5-GeV Electron Linac linac, electron, SLAC, feedback 2703
 
  • S.S. Park, J. Choi, J.Y. Huang, S.H. Kim, S.-C. Kim
    PAL, Pohang, Kyungbuk
  The klystron-modulator(K&M) system of the Pohang Accelerator Laboratory (PAL) generates high power microwaves for the acceleration of 2.5 GeV electron beams. There are 12 modules of K&M system to accelerate electron beams up to 2.5 GeV nominal beam energy. One module of the K&M system consists of the 200 MW modulator and an 80 MW S-band (2856 MHZ) klystron tube. The total accumulated high-voltage run-time of the oldest unit among the 12 K&M systems has reached nearly 88,000 hours as of December 2005. The overall system availability is well over 95%. In this paper, we review the overall system performance of the high-power K&M system and the operational status of the klystrons and thyratron lifetimes, and the overall system's availability will be analyzed for the period of 1994 to December 2005.  
 
THPCH023 Vlasov Equilibrium of a Periodically Twisted Ellipse-shaped Charged-particle Beam in a Non-axisymmetric Periodic Magnetic Focusing Field focusing, emittance, plasma, permanent-magnet 2826
 
  • J.Z. Zhou, C. Chen
    MIT/PSFC, Cambridge, Massachusetts
  A new Vlasov equilibrium is obtained for a periodically twisted ellipse-shaped charged-particle beam in a non-axisymmetric periodic permanent magnetic focusing field. The equilibrium distribution function is derived, and the statistical properties of the beam equilibrium are studied. The generalized envelope equations derived from the kinetic theory recovers the generalized envelope equations obtained in the cold-fluid theory when the temperature is taken to be zero*. Examples of periodically twisted elliptic beam equilibrium are presented and applications are explored.

*J. Zhou et al. “Exact Paraxial Cold-Fluid Equilibrium of a High-Intensity Periodically Twisted Ellipse-Shaped Charged-Particle Beam,” Phys. Rev. ST Accel. Beams, submitted for publication (2005).

 
 
THPCH101 Modeling and Simulation of Longitudinal Dynamics for LER-HER PEP II Rings simulation, feedback, impedance, controls 3032
 
  • C.H. Rivetta, J.D. Fox, T. Mastorides, D. Teytelman, D. Van Winkle
    SLAC, Menlo Park, California
  A time domain dynamic model and simulation tool for beam-cavity interactions in LER and HER rings at PEP II is presented. The motivation for this tool is to explore the stability margins and performance limits of PEP II LLRF systems at higher currents and upgraded RF configurations. It also serves as test bed for new control algorithms and to define the ultimate limits of the architecture. The tool captures the dynamical behavior of the beam-cavity interaction based on a reduced model. It includes nonlinear elements in the klystron and signal processing. The beam current is represented by macro-bunches. Multiple RF stations in the ring are represented via one or two single macro-cavities. Each macro-cavity captures the overall behavior of all the 2 or 4 cavity RF stations. This allows modeling the longitudinal impedance control loops interacting with the longitudinal beam model. Validation of simulation tool is in progress by comparing the measured growth rates for both LER and HER rings with simulation results. The simulated behavior of both machines at high currents are presented comparing different control strategies and the effect of non-linear klystrons and the linearizer.  
 
THPCH146 Solid State Modulators for the International Linear Collider (ILC) linear-collider, collider, power-supply, controls 3131
 
  • M.A. Kempkes, N. Butler, J.A. Casey, M.P.J. Gaudreau, I. Roth
    Diversified Technologies, Inc., Bedford
  Diversified Technologies, Inc. (DTI) is developing two solid-state modulator designs for the International Linear Collider with SBIR funding from the U.S. Department of Energy. This paper will discuss design tradeoffs, energy storage requirements and alternatives, and the construction and test status of both ILC designs. The first design is a 150 kV hard switch, employing an innovative energy storage system, which must provide 25 kJ per pulse at very tight voltage regulation over the 1.5 millisecond pulse. DTI's design uses a quasi-resonant bouncer (with a small auxiliary power supply and switch) to maintain the voltage flattop, eliminating the need for massive capacitor banks. The second design builds upon earlier DTI work for the 500 kV, 500 A NLC modulators. It uses a solid-state Marx bank, with ~10 kV stages, to drive the ILC klystron. Staggered turn-on of the Marx stages provides voltage regulation without the need for large capacitor banks.  
 
THPCH194 Investigation of Using Ferroelectric Materials in High Power Fast RF Phase Shifters for RF Vector Modulation insertion, controls, simulation, resonance 3248
 
  • J.L. Wilson, Y.W. Kang
    ORNL, Oak Ridge, Tennessee
  • A.E. Fathy
    University of Tennessee, Knoxville, Tennessee
  A fast ferroelectric phase shifter controlled by an electric field bias is being investigated for high-power RF phase shifters in vector modulation. Such a device could be used in charged particle accelerators, allowing vector control of the RF power delivered to accelerating RF cavities. Bulk ferroelectric materials, particularly those based on barium-strontium titanate (BST) compounds, have shown promise in high-power applications because of their low loss tangent and high dielectric strength. Such materials have already been investigated for use in fast phase shifters at X-Band frequencies*. Several different compositions of BST compounds are investigated in phase shifter prototypes at 402.5 MHz and 805 MHz that could be easily adapted for future large-scale accelerator projects. The ratio of barium versus strontium in the composition is varied from sample to sample. This allows an investigation of the tradeoffs involved between dielectric strength, loss tangent, tunability, and relative permittivity. Since ferroelectrics are by nature nonlinear dielectric compounds, preliminary study on the nonlinear propagation effects is conducted through computer simulation.

*V. P. Yakovlev et al. Fast X-Band Phase Shifter, Advanced Accelerator Concepts: Eleventh Workshop, 2004.