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Beard, C.D.

Paper Title Page
MOPCH065 Fabrication and Installation of Superconducting Accelerator Modules for the ERL Prototype (ERLP) at Daresbury 178
 
  • P. vom Stein, S. Bauer, M. Pekeler, H. Vogel
    ACCEL, Bergisch Gladbach
  • R. Bate, C.D. Beard, D.M. Dykes, P.A. McIntosh, B. Todd
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
 
  Installation and commissioning of the superconducting energy recovery linac(ERL) prototype is under way at Daresbury Laboratory. ACCEL have manufactured two superconducting accelerator modules for the injector and the linac, operating at 2K with 1.3 GHz TESLA type cavities. Each module contains two cavities and is designed to provide an accelerating voltage of 25 MV in cw mode. This paper presents details of the module fabrication, cavity preparation and performance results. An overview of the cryogenic installations for the modules is given and status results of the commissioning are discussed.  
MOPCH159 Coupler Design Considerations for the ILC Crab Cavity 430
 
  • P. Goudket, C.D. Beard
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • G. Burt
    Microwave Research Group, Lancaster University, Lancaster
 
  Transverse deflecting cavities, such as the ILC crab cavity, commonly operate in the TM110 dipole mode. This means that in addition to the higher order modes (HOMs), that need to be controlled for every cavity, the fundamental TM010 mode and the other polarisation of the dipole mode also need to be damped. As the resonant frequency of the fundamental mode is much lower than the cut-off frequency of the beampipe, this mode becomes trapped in the cavity and difficult to extract using conventional HOM couplers, hence a dedicated coupler is likely to be required. The ILC crab cavities will require excellent damping of all undesirable modes in order to maintain maximum luminosity at the IP.  
MOPCH161 Development of a Prototype Superconducting CW Cavity and Cryomodule for Energy Recovery 436
 
  • P.A. McIntosh, C.D. Beard, D.M. Dykes, B. Todd
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • S.A. Belomestnykh
    Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York
  • A. Buechner, P. Michel, J. Teichert
    FZR, Dresden
  • J.M. Byrd, J.N. Corlett, D. Li
    LBNL, Berkeley, California
  • T. Kimura, T.I. Smith
    Stanford University, Stanford, Califormia
  • M. Liepe, V. Medjidzade, H. Padamsee, J. Sears, V.D. Shemelin
    Cornell University, Ithaca, New York
  • D. Proch
    DESY, Hamburg
 
  Energy Recovery LINAC (ERL) and LINAC-driven FEL proposals and developments are now widespread around the world. Superconducting RF (SRF) cavity advances made over the last 10 years for TESLA/TTF at 1.3 GHz, in reliably achieving accelerating gradients >20 MV/m, suggest their suitability for these ERL and FEL accelerators. Typically however, photon fluxes are maximised from the associated insertion devices when the electron bunch repetition rate is as high as possible, making CW-mode operation at high average current a fundamental requirement for these light sources. Challenges arise in controlling the substantial HOM power and in minimizing the power dissipated at cryogenic temperatures during acceleration and energy recovery, requiring novel techniques to be employed. This paper details a collaborative development for an advanced high-Qo cavity and cryomodule system, based on a modified TESLA cavity, housed in a Stanford/Rossendorf cryomodule. The cavity incorporates a Cornell developed resistive-wall HOM damping scheme, capable of providing the improved level of HOM damping and reduced thermal load required.  
MOPCH162 RF Requirements for the 4GLS Linac Systems 439
 
  • P.A. McIntosh, C.D. Beard, D.M. Dykes, A.J. Moss
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
 
  The 4GLS facility at Daresbury will combine energy recovery linac (ERL) and free electron laser (FEL) technologies to deliver a suite of naturally synchronised state-of-the-art sources of synchrotron radiation and FEL radiation covering the terahertz (THz) to soft X-ray regimes. CW-mode operation at high acceleration gradients are needed for the various 4GLS accelerator systems and here is where Superconducting Radio Frequency (SRF) cavities excel. Since resistive losses in the cavity walls increase as the square of the accelerating voltage, conventional copper cavities become uneconomical when the demand for high CW voltage grows with particle energy requirements. After accounting for the refrigeration power needed to provide the liquid helium operating temperature, a net power gain of several hundred remains for SRF over conventional copper cavities. This paper details the RF requirements for each of the SRF accelerating stages of the 4GLS facility, outlining techniques necessary to cope with CW-mode operation and HOM power generation.  
MOPCH163 Analysis of Wakefields in the ILC Crab Cavity 442
 
  • G. Burt, A.C. Dexter
    Microwave Research Group, Lancaster University, Lancaster
  • C.D. Beard, P. Goudket
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • L. Bellantoni
    Fermilab, Batavia, Illinois
  • R.M. Jones
    UMAN, Manchester
 
  The large crossing angle schemes of the ILC need a correction of bunch orientation at the IP in order to recover a luminosity loss of up to 80%. The orientation of bunches can be changed using a transverse deflecting cavity. The location of the crab cavity would be close to the final focus, and small deflections caused by wakefields in the cavities could cause misalignments of the bunches at the IP. Wakefields in the FNAL CKM cavities have been analysed and their effects studied in view of use as the ILC crab cavity. Numerical simulations have been performed to analyse the transverse wakepotentials of up to quadrupole order modes in this cavity and the effect upon bunches passing through this cavity. Trapped modes within the CKM cavity have been investigated. Perturbation tests of normal conducting models of this cavity have been launched to verify these results. The effect of the final focus quadrupole magnets on the deflection given to the bunch have also been calculated and used to calculate luminosity loss due to wakefields.  
MOPLS066 Direct Measurement of Geometric and Resistive Wakefields in Tapered Collimators for the International Linear Collider 697
 
  • N.K. Watson, D. Adey, M.C. Stockton
    Birmingham University, Birmingham
  • D.A.-K. Angal-Kalinin, C.D. Beard, J.L. Fernandez-Hernando, F. Jackson
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • R. Arnold, R.A. Erickson, C. Hast, T.W. Markiewicz, S. Molloy, M.C. Ross, S. Seletskiy, A. Seryi, Z. Szalata, P. Tenenbaum, M. Woodley, M. Woods
    SLAC, Menlo Park, California
  • R.J. Barlow, A. Bungau, R.M. Jones, G.Yu. Kourevlev, A. Mercer
    UMAN, Manchester
  • D.A. Burton, J.D.A. Smith, A. Sopczak, R. Tucker
    Lancaster University, Lancaster
  • C. Densham, G. Ellwood, R.J.S. Greenhalgh, J. O'Dell
    CCLRC/RAL, Chilton, Didcot, Oxon
  • Y.K. Kolomensky
    UCB, Berkeley, California
  • M. Kärkkäinen, W.F.O. Müller, T. Weiland
    TEMF, Darmstadt
  • N. Shales
    Microwave Research Group, Lancaster University, Lancaster
  • M. Slater
    University of Cambridge, Cambridge
  • I. Zagorodnov
    DESY, Hamburg
  • F. Zimmermann
    CERN, Geneva
 
  Precise collimation of the beam halo is required in the ILC to prevent beam losses near the interaction region that could cause unacceptable backgrounds for the physics detector. The necessarily small apertures of the collimators lead to transverse wakefields that may result in beam deflections and increased emittance. A set of collimator wakefield measurements has previously been performed in the ASSET region of the SLAC LINAC. We report on the next phase of this programme, which is carried out at the recently commissioned End Station A test facility at SLAC. Measurements of resistive and geometric wakefields using tapered collimators are compared with model predictions from MAFIA and GdfidL and with analytic calculations.  
MOPLS067 Test Beam Studies at SLAC's End Station A, for the International Linear Collider 700
 
  • M. Woods, C. Adolphsen, R. Arnold, G.B. Bowden, G.R. Bower, R.A. Erickson, H. Fieguth, J.C. Frisch, C. Hast, R.H. Iverson, Z. Li, T.W. Markiewicz, D.J. McCormick, S. Molloy, J. Nelson, M.T.F. Pivi, M.C. Ross, S. Seletskiy, A. Seryi, S. Smith, Z. Szalata, P. Tenenbaum
    SLAC, Menlo Park, California
  • D. Adey, M.C. Stockton, N.K. Watson
    Birmingham University, Birmingham
  • M. Albrecht, M.H. Hildreth
    Notre Dame University, Notre Dame, Iowa
  • W.W.M. Allison, V. Blackmore, P. Burrows, G.B. Christian, C.C. Clarke, G. Doucas, A.F. Hartin, B. Ottewell, C. Perry, C. Swinson, G.R. White
    OXFORDphysics, Oxford, Oxon
  • D.A.-K. Angal-Kalinin, C.D. Beard, J.L. Fernandez-Hernando, F. Jackson, A. Kalinin
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • R.J. Barlow, A. Bungau, G.Yu. Kourevlev, A. Mercer
    UMAN, Manchester
  • S.T. Boogert
    Royal Holloway, University of London, Surrey
  • D.A. Burton, J.D.A. Smith, R. Tucker
    Lancaster University, Lancaster
  • W.E. Chickering, C.T. Hlaing, O.N. Khainovski, Y.K. Kolomensky, T. Orimoto
    UCB, Berkeley, California
  • C. Densham, R.J.S. Greenhalgh
    CCLRC/DL, Daresbury, Warrington, Cheshire
  • V. Duginov, S.A. Kostromin, N.A. Morozov
    JINR, Dubna, Moscow Region
  • G. Ellwood, P.G. Huggard, J. O'Dell
    CCLRC/RAL, Chilton, Didcot, Oxon
  • F. Gournaris, A. Lyapin, B. Maiheu, S. Malton, D.J. Miller, M.W. Wing
    UCL, London
  • M.B. Johnston
    University of Oxford, Clarendon Laboratory, Oxford
  • M.F. Kimmitt
    University of Essex, Physics Centre, Colchester
  • H.J. Schriber, M. Viti
    DESY Zeuthen, Zeuthen
  • N. Shales, A. Sopczak
    Microwave Research Group, Lancaster University, Lancaster
  • N. Sinev, E.T. Torrence
    University of Oregon, Eugene, Oregon
  • M. Slater, M.T. Thomson, D.R. Ward
    University of Cambridge, Cambridge
  • Y. Sugimoto
    KEK, Ibaraki
  • S. Walston
    LLNL, Livermore, California
  • T. Weiland
    TEMF, Darmstadt
  • M. Wendt
    Fermilab, Batavia, Illinois
  • I. Zagorodnov
    DESY, Hamburg
  • F. Zimmermann
    CERN, Geneva
 
  The SLAC Linac can deliver to End Station A a high-energy test beam with similar beam parameters as for the International Linear Collider for bunch charge, bunch length and bunch energy spread. ESA beam tests run parasitically with PEP-II with single damped bunches at 10Hz, beam energy of 28.5 GeV and bunch charge of (1.5-2.0)·1010 electrons. A 5-day commissioning run was performed in January 2006, followed by a 2-week run in April. We describe the beamline configuration and beam setup for these runs, and give an overview of the tests being carried out. These tests include studies of collimator wakefields, prototype energy spectrometers, prototype beam position monitors for the ILC Linac, and characterization of beam-induced electro-magnetic interference along the ESA beamline.  
MOPLS070 Numerical Calculations of Collimator Insertions 709
 
  • C.D. Beard
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • J.D.A. Smith
    Cockcroft Institute, Warrington, Cheshire
 
  A series of collimator spoilers have been designed and manufactured for testing in the ESA wakefield tests. The purpose of the tests is a benchmarking exercise to assist with the understanding into the causes of wakefields due to spoiler profile and materials. Simulations of the spoiler designs have been used to understand the likely effects that would be observed with the beam tests. Simulations of these collimator insertions have been carried out in MAFIA and GDFIDL, and a comparison of the results completed. The wake potential has been measured, and the corresponding loss factor and kick factors have been calculated. The results from the simulations are discussed in this report.  
MOPLS071 TDR Measurements in support of ILC Collimator Studies 712
 
  • C.D. Beard, P.A. Corlett, A.J. Moss, J.H.P. Rogers
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • R.M. Jones
    Cockcroft Institute, Warrington, Cheshire
 
  In this report the outcome of the "wire method" cold test, experimental results and their relevance toward the ILC set-up is considered. A wire is stretched through the centre of a vessel along the axis that the electron beam would take, and a voltage pulse representing the electron bunch is passed along the wire. The parasitic mode loss parameter from this voltage can then be measured. The bunch length for the ILC is 0.3mm, requiring a pulse rise time of ~1ps. The fastest rise time available for a time domain reflectrometry (TDR) scope is ~10ps. Reference vessels have been examined to evaluate the suitability of the test gear at comparable bunch structures to the ILC.  
MOPLS075 Progress towards Crab Cavity Solutions for the ILC 724
 
  • G. Burt, A.C. Dexter
    Cockcroft Institute, Warrington, Cheshire
  • C.D. Beard, P. Goudket
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • L. Bellantoni
    Fermilab, Batavia, Illinois
 
  In order to achieve acceptable luminosity for ILC crossing angles greater than a few mrad, RF deflection cavities must be used to rotate electron and position bunches leading up to the IP. A bunch that passes through a deflection cavity at a phase where the deflection averages to zero receives a crab kick leading to a finite rotation at the IP. For a beam energy of 500GeV and a crossing angle of 20mrad, the required crab kick is about 19.5MV at 1.3GHz and 6.5MV at 3.9GHz. Cavities are needed on both beams and are likely to be positioned about 12m before the IP. Any RF phase error between the bunch and the cavity leads to a deflection of the bunch in addition to a rotation of the bunch. Any differential phase error between the cavities leads to differing deflections and consequential loss in luminosity. Collaborative work with FNAL, being undertaken to develop a variant of their 3.9GHz CKM cavity optimised for an ILC solution, is described. Current analysis favours a solution with four nine-cell cavities on each beam. It is anticipated that the cavities will be run CW and driven from small Klystron/s (< 5kW) or solid state amplifiers.*

*We would like to thank Chris Adolphsen, SLAC, for his help in technical discussions, which were greatly appreciated.

 
WEPLS047 3-1/2 Cell Superconducting RF Gun Simulations 2481
 
  • C.D. Beard, J.H.P. Rogers
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • F. Staufenbiel, J. Teichert
    FZR, Dresden
 
  A 3-1/2 cell superconducting RF photocathode gun is being developed at Forschungszentrum Rossendorf to produce a high peak current, low emittance electron beam. This technology is essential to the realisation of many large scale facilities. The gun is designed for CW operation mode with 1 mA current and 9.5 MeV electron energy, and it will be installed at the ELBE superconducting electron linear accelerator. The gun will have a 3-1/2 cell niobium cavity operating at 1.3 GHz. The cavity consists of three cells with TESLA geometry and a specially designed half-cell in which the photocathode will be placed. Typical ERL-based projects require ~100 mA average current, and therefore suitable upgrade paths are required. Simulations have been carried out to evaluate the design and to determine suitable upgrades for higher current operation. Simulations of alternative cathode surface shapes are presented. Several couplers have been identified that can provide higher power to the cavity, whose integration and suitability has been verified. All the investigations that have identified possible solutions to higher current operation are discussed in this report.