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MOZBPA02 A Review of ERL Prototype Experience and Light Source Design Challenges ERL, FEL, linac, superconducting-RF 39
 
  • S.L. Smith
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  The presentation will review the status of commissioning of ERL light source prototype projects drawing on experience from the JLab IR FEL, UK's ERL prototype ring and the Cornell injector project. State of the art design for future light source based on ERLs and FELs will be illustrated using the concept for the UK's 4GLS project.  
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MOPCH010 High Power Tests of a High Duty Cycle, High Repetition Rate RF Photoinjector Gun for the BESSY FEL DESY, PITZ, FEL, klystron 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.  
 
MOPCH025 Laser Comb: Simulations of Pre-modulated E- Beams at the Photocathode of a High Brightness RF Photoinjector laser, electron, cathode, simulation 98
 
  • M. Boscolo, M. Ferrario, C. Vaccarezza
    INFN/LNF, Frascati (Roma)
  • I. Boscolo, F. Castelli, S. Cialdi
    INFN-Milano, Milano
  • P. Musumeci
    INFN-Roma, Roma
  A density modulated beam at the photocathode though the proper modulation of the laser beam pulse does not change substantially emittance and energy spread, properties directly related to FEL. It has been found that bunch density modulation is transformed into energy modulation along the propagation through the injector*. There are some physical arguments that suggest a possibility to use this modulation for the enhancement of the FEL process, or for the production of plasma wakes. Preliminary beam dynamics studies have been carried on to explore the use of electron beam pre-modulation at the cathode to adjust their longitudinal structure at the end of the beamline. Energy modulation at the end of the beamline could eventually be turned into current modulation through a magnetic compressor with R56<0. The feasibility of this experiment has to be investigated carefully, preliminary studies are discussed here. This paper focuses on simulations that explore the properties of the energy modulation at the end of the beamline correlated to the initial characteristics of the train of electron pulses.

*M. Biagini et al. “Beam Dynamics Studies for the SPARC Project”, Proc. of PAC03.

 
 
MOPCH027 Metal Film Photocathodes for High Brightness Electron Injectors laser, cathode, vacuum, target 104
 
  • G. Gatti, L. Cultrera, F. Tazzioli, C. Vicario
    INFN/LNF, Frascati (Roma)
  • A. Fiori, S. Orlanducci
    Università di Roma II Tor Vergata, Roma
  • J. Langner, M. S. Sadowski, P. Strzyzewski
    The Andrzej Soltan Institute for Nuclear Studies, Centre Swierk, Swierk/Otwock
  • A. Perrone
    INFN-Lecce, Lecce
  • C. Ristoscu
    INFLPR, Bucharest - Magurele
  Advanced high brightness injectors require photocathodes with fast response,high quantum efficiency and good surface uniformity. Both Mg films deposited by laser ablation and Pb films deposited by vacuum arc could satisfy these requirements. Their emission and morphology are compared.  
 
MOPCH029 Status of the SPARC Project laser, emittance, undulator, electron 110
 
  • P. Musumeci, D. Levi, M. Mattioli, G. Medici, D. Pelliccia, M. Petrarca
    Università di Roma I La Sapienza, Roma
  • D. Alesini, M. Bellaveglia, S. Bertolucci, R. Boni, M. Boscolo, M. Castellano, A. Clozza, L. Cultrera, G. Di Pirro, A. Drago, A. Esposito, M. Ferrario, L. Ficcadenti, D. Filippetto, V. Fusco, A. Gallo, G. Gatti, A. Ghigo, M. Incurvati, C. Ligi, F. Marcellini, M. Migliorati, A. Mostacci, L. Palumbo, L. Pellegrino, M.A. Preger, R. Ricci, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, A. Stecchi, A. Stella, F. Tazzioli, C. Vaccarezza, M. Vescovi, C. Vicario
    INFN/LNF, Frascati (Roma)
  • F. Alessandria, A. Bacci, I. Boscolo, F. Broggi, S. Cialdi, C. De Martinis, D. Giove, C. Maroli, M. Mauri, V. Petrillo, M. Rome, A.R. Rossi, L. Serafini
    INFN-Milano, Milano
  • L. Catani, E. Chiadroni, A. Cianchi, E. Gabrielli, S. Tazzari
    INFN-Roma II, Roma
  • F. Ciocci, G. Dattoli, A. Dipace, A. Doria, G.P. Gallerano, L. Giannessi, E. Giovenale, G. Messina, P.L. Ottaviani, S. Pagnutti, L. Picardi, M. Quattromini, A. Renieri, G. Ronci, C. Ronsivalle, M. Rosetti, E. Sabia, M. Sassi, A. Torre, A. Zucchini
    ENEA C.R. Frascati, Frascati (Roma)
  • A. Perrone
    INFN-Lecce, Lecce
  • S. Reiche, J.B. Rosenzweig, G. Travish
    UCLA, Los Angeles, California
  The SPARC Project is starting the commissioning of its photo-injector. RF gun, RF sources, RF network and control, power supplies, emittance meter, beam diagnostics and control to measure the RF gun beam are installed. The photocathode drive laser has been characterized in terms of pulse shape and quality. We expect to conduct beam measurements at RF gun exit in the next future and consequently to start the installation of accelerating sections. The design of the 12 m undulator for the FEL experiment has been completed and the first undulator section out of 6 is under construction: we expect to characterize it at Frascati ENEA laboratory within the next months. SPARC as a facility will host FEL experiments using SASE, seeding and non-linear resonant harmonics. Additional R&D on X-band and S-band structures for velocity bunching are in progress, as well as studies on new photocathode materials and exotic undulator designs. We also present studies on solenoid field defects, beam based alignments, exotic electron bunch production (blow-out of short laser pulses or intensity modulated laser pulses). The possible use of segmented superconducting micro-undulators will be discussed too.  
 
MOPCH036 Photocathode Roughness Impact on Photogun Beam Characteristics emittance, cathode, electron, FEL 121
 
  • T.V. Gorlov
    MEPhI, Moscow
  • A.M. Tron
    LPI, Moscow
  Photocathode surface roughness has an impact on photoelectron yield, bunch duration, beam emittance at the exit of femtosecond photogun with an accelerating field that is considered in assumption of quasi-stationary one in the paper. The main problem in investigating the impact is determination of the field near the surface, statistical properties of which are defined through rms values of deviation and slope in profile line of the surface roughness. Developed and created code allows determining the field with relative rms error not worse than 0.001%. The results of the investigation for rms values of roughness and its slope within respectively 500…0 nm and 20…0 degrees are presented and discussed.  
 
MOPCH040 Simulations for the FEL Test Facility at MAX-lab within EUROFEL FEL, undulator, electron, simulation 127
 
  • S. Thorin, M. Brandin, S. Werin
    MAX-lab, Lund
  • M. Abo-Bakr, J. Bahrdt, K. Goldammer
    BESSY GmbH, Berlin
  Within the EUROFEL project a High Gain Harmonic Generation Free Electron Laser will be constructed at MAX-lab in collaboration with BESSY. The electron bunches will be created in the existing MAX-lab injector and transported to the inside of the MAX II ring where the FEL undulators will be located. To predict FEL performance and stability, simulations of the photo injector, linac, recirculator, transport and undulator sections as well as start to end simulations have been carried out.  
 
MOPCH041 Design of a New Preinjector for the MAX Recirculator to be Used in EUROFEL emittance, linac, cathode, simulation 130
 
  • S. Werin, M. Brandin, T. Hansen, D. Kumbaro, L. Malmgren, S. Thorin
    MAX-lab, Lund
  • J. Bahrdt
    BESSY GmbH, Berlin
  The MAX-lab recirculator injector will be equipped with a new preinjector system. The aim is to reduce the emittance, increase the charge and achieve a proper timing between accelerator and laser systems. All is aimed at the MAX-lab test facility for HG built in collaboration with BESSY in the EUROFEL program. The preinjector system consists of a photo cathode RF-gun with an emittance compensating solenoid. Special issues regard the injection of the new beam into the beam path of the MAX recirculator and the conservation of beam parameters.  
 
MOPCH070 The Status of the Daresbury Energy Recovery Prototype Project ERLP, linac, diagnostics, electron 187
 
  • D.J. Holder, J.A. Clarke, P.A. McIntosh, M.W. Poole, S.L. Smith
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • N. Bliss
    CCLRC/DL, Daresbury, Warrington, Cheshire
  • E.A. Seddon
    CCLRC/DL/SRD, Daresbury, Warrington, Cheshire
  The major component of the UK's R&D programme towards an advanced energy recovery linac-based light source facility is a 35 MeV technology demonstrator called the energy recovery linac prototype (ERLP). This is based on a combination of a DC photocathode electron gun, a superconducting linac operated in energy recovery mode and an IR FEL. The current status of the of this project is presented, including the construction and commissioning progress and plans for the future exploitation of this scientific and technical R&D facility.  
 
MOPCH158 HIPPI Triple-spoke Cavity Design simulation, electron, vacuum, resonance 427
 
  • E. Zaplatin, M. Pap, R. Tölle
    FZJ, Jülich
  In the frames of the European project of High Intensity Pulsed Proton Injector (HIPPI) the 352 MHz, beta=0.48 triple-spoke cavity is under development and will be built at the research center FZJ in Juelich. The criteria and results of the cavity RF and structural analyses are presented.  
 
MOPLS059 The Probe Beam Linac in CTF3 linac, CLIC, CTF3, emittance 679
 
  • A. Mosnier, M. Authier, D. Bogard, A. Curtoni, O. Delferriere, G. Dispau, R. Duperrier, W. Farabolini, P. Girardot, M. Jablonka, J.L. Jannin, M. Luong, F. Peauger
    CEA, Gif-sur-Yvette
  • N. Rouvière
    IPN, Orsay
  • R. Roux
    LAL, Orsay
  The test facility CTF3, presently under construction at CERN within an international collaboration, is aimed at demonstrating the key feasibility issues of the multi-TeV linear collider CLIC. The objective of the probe beam linac is to "mimic" the main beam of CLIC in order to measure precisely the performances of the 30 GHz CLIC accelerating structures. In order to meet the required parameters of this 200 MeV probe beam, in terms of emittance, energy spread and bunch-length, the most advanced techniques have been considered: laser triggered photo-injector, velocity bunching, beam-loading compensation, RF pulse compression … The final layout is described, and the selection criteria and the beam dynamics results are reviewed.  
 
MOPLS114 Construction of the Probe Beam Photo-injector of CTF3 emittance, vacuum, simulation, laser 828
 
  • J. Brossard, M. Desmons, B.M. Mercier, C.P. Prevost, R. Roux
    LAL, Orsay
  The paper describes the HF and dynamic beam modelling performed onto the 3 GHz / 2,5 cells photo-injector of the future CTF3 (CLIC Test Facility 3) probe beam linac, whose goal is to demonstrate the feasibility of the 30 GHz accelerating sections in the framework of the CLIC project. The Probe Beam Photo-Injector (PBPI) conception is inspired from the drive beam photo-injector already designed by LAL (Orsay, France) and actually tested in our laboratory. However, the design of PBPI has been simplified with respect to the previous because the charge per bunch is 4 times lower and the number of bunches several orders of magnitude smaller. The internal geometry and the coupling system of the PBPI have been designed with 2D (SUPERFISH) and 3D (HFSS, ANSYS) codes. A detailed analysis of the dissymmetry (induced by the coupling system) of the accelerating field component has been performed. Based on the modified design, PARMELA simulations showed that the technical specifications are fulfilled. The vacuum issue has been also carefully investigated, and NEG (Non Evaporated Getter) technology has been adopted in order to reach the 10-10 mbar pressure inside the structure.  
 
MOPLS129 Integration of the PHIN RF Gun into the CLIC Test Facility emittance, CTF3, CERN, bunching 861
 
  • S. Doebert
    CERN, Geneva
  CERN is a collaborator within the European PHIN project, a joint research activity for Photo injectors within the CARE program. The scope of this project is to build an RF Gun equipped with high quantum efficiency Cs2Te cathodes and a laser to produce the nominal beam for the CLIC Test Facility (CTF3). The nominal beam for CTF3 has an average current of 3.5 A, 1.5 GHz bunch repetition frequency and a pulse length of 1.5 us (2310 bunches) with quite tight stability requirements. In addition a phase shift of 90 deg is needed after each train of 140 ns for the special CLIC combination scheme. This RF Gun will be tested at CERN in fall 2006 and should be integrated as a new injector into the CTF3 linac, replacing the existing injector consisting of a thermionic gun and a subharmonic bunching system. The paper studies the optimal integration into the machine trying to optimize transverse and longitudinal phase space of the beam while respecting the numerous constraints of the existing accelerator. The presented scheme uses emittance compensation and velocity bunching to fulfill the requirements.  
 
TUPCH025 Precision RF Gun Phase Monitor System for the VUV-FEL laser, electron, acceleration, power-supply 1052
 
  • H. Schlarb, N. Heidbrook, H. Kapitza, F. Ludwig, N. Nagad
    DESY, Hamburg
  For RF photo-injectors, the properties of the high brightness beam critically depend on the synchronization between the RF gun acceleration phase and the photo-cathode laser. At the VUV-FEL, the phase stability is determined by operating the RF gun close to zero-crossing RF phase. This allows the conversion of phase variations into charge variations which then is readout by a precision charge measurement system based on toroids. In this paper, we discuss the limitation of this method. Resolution reduction of the charge measurement system due to electro-magnetic-interference is discussed in detail.  
 
TUPCH039 A Phase Space Tomography Diagnostic for Pitz space-charge, quadrupole, diagnostics, PITZ 1091
 
  • D.J. Holder, B.D. Muratori
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • F.E. Hannon
    Jefferson Lab, Newport News, Virginia
  • S. Khodyachykh, A. Oppelt
    DESY Zeuthen, Zeuthen
  The Photo Injector Test Facility at DESY in Zeuthen (PITZ) is a European collaboration developing RF photocathode electron guns for light source and linear collider projects. As part of the collaborative work being partially funded by the EU's FP6 programme, CCLRC Daresbury Laboratory and DESY are designing and building a phase space tomography diagnostic based on a set of multiple quadrupoles and view screens. In order to measure the beam emittance, four screens with intermediate quadrupole doublets will be used. The equipment will be installed and tested at PITZ as part of the facility upgrade presently ongoing. Following simulations of the gun using the ASTRA code at a range of energies, simulations of the electron beam parameters through the matching and tomography sections must be undertaken in order to specify the optimum arrangement of magnets and screens.  
 
TUPCH112 Commissioning of the 100 MeV Preinjector HELIOS for the SOLEIL Synchrotron emittance, linac, beam-loading, SOLEIL 1274
 
  • A.S. Setty, D. Jousse, J.-L. Pastre, F. Rodriguez
    THALES, Colombes
  • R. Chaput, J.-P. Pollina, B. Pottin, M.-A. Tordeux
    SOLEIL, Gif-sur-Yvette
  • A. Sacharidis
    EuroMev, Buc
  HELIOS is the 100 MeV electron linac pre-injector of SOLEIL the new French SR facility. It has been supplied by THALES, as a turn-key system on the basis of SOLEIL APD design. The linac was commissioned in October 2005. This paper will remind the main features of the linac, especially on beam-loading compensation, and will give results obtained during the commissioning tests where a special care has been taken for emittance measurements. Specified and measured beam parameters will be compared to show the performance of the entire system.  
 
TUPCH113 Construction of the ALPHA-X Photo-injector Cavity vacuum, cathode, electron, injection 1277
 
  • J. Rodier, T. Garvey
    LAL, Orsay
  • D.A. Jaroszynski, V.M. Pavlov, Y.M. Saveliev, M. Wiggins
    USTRAT/SUPA, Glasgow
  • M.J. de Loos, S.B. van der Geer
    PP, Soest
  We will describe the construction and low power testing of an RF cavity to be used as a photo-injector for the ALPHA-X project within the Department of Physics at the University of Strathclyde (UK). The gun is a two and a half cell S-band cavity, employing a metallic photo-cathode. RF power is coupled to the gun via a co-axial power coupler. The specification of the gun and the low power measurements made to achieve the correct mode frequency and field flatness will be presented.  
 
TUPCH156 Design and Simulation of a Cusp Gun for Gyro-amplifier Application in High Frequency RF Accelerators electron, cathode, simulation, cyclotron 1391
 
  • D.H. Rowlands, A.W. Cross, W. He, A. Phelps, E.G. Rafferty, C.W. Robertson, K. Ronald, J. Thomson, C.G. Whyte, A.R. Young
    USTRAT/SUPA, Glasgow
  Gyro-amplifiers have potential as the high frequency RF drivers for particle accelerators. They require relativistic electron beams with low velocity spread and with a high fraction of the electron energy associated with the cyclotron motion. For harmonic operation and mode control an axis-encircling beam is desirable. The passage of an electron beam through a non-adiabatic magnetic field reversal (cusp) converts part of the electron beam's axial velocity into axis-encircling transverse velocity. A cusp-based electron beam forming system, yielding a 10MW, 150kV, 70A axis-encircling beam will be presented. This cusp gun is being designed as the electron beam source for a microwave gyro-amplifier that is relevant for high frequency accelerator applications. The latest results from numerical simulations and experiments will be presented and compared.  
 
TUPCH166 Multi-megawatt Harmonic Multiplier for Testing High-gradient Accelerator Structures klystron, SLAC, 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.  
 
TUPCH189 FPGA-based RF Field Control at the Photocathode RF Gun of the DESY VUV-FEL controls, FIR, electron, DESY 1456
 
  • E. Vogel, W. Koprek, P. Pucyk
    DESY, Hamburg
  At the DESY Vacuum Ultraviolet Free Electron Laser (VUV-FEL) bunch peak current and the SASE effect are (amongst other parameters) sensitive to beam energy and beam phase variations. The electron bunches are created in an rf gun, which does not have field probes. Variations of the gun rf field cause beam energy and phase variations. They have a significant influence on the overall performance of the facility. DSP based rf field control used previously was only able to stabilize the rf output of the klystron. This was due to the lack of processing power and the over-all loop delay. The controller was not able to provide satisfactory rf field stability in the gun. Replacing the DSP hardware by the new FPGA-based hardware Simulation Controller (SimCon), we are able to reduce the latency within the digital part significantly allowing for higher loop gain. Furthermore SimCon provides sufficient processing power for calculating a probe signal from the forward and reflected power as input for PI and adaptive feed forward (AFF) control. In this paper we describe the algorithms implemented and the gun rf field stability obtained.  
 
TUPLS064 Design and Commissioning of a Compact Electron Cooler for the S-LSR electron, cathode, proton, ion 1639
 
  • H. Fadil, S. Fujimoto, A. Noda, T. Shirai, H. Souda, H. Tongu
    Kyoto ICR, Uji, Kyoto
  • T. Fujimoto, S.I. Iwata, S. Shibuya
    AEC, Chiba
  • M. Grieser
    MPI-K, Heidelberg
  • K. Noda
    NIRS, Chiba-shi
  • I.A. Seleznev, E. Syresin
    JINR, Dubna, Moscow Region
  The ion cooler ring S-LSR has been constructed and commissioned in October 2005. The ring successfully stored a 7 MeV proton beam. The S-LSR is equipped with a compact-electron cooler which has a cooling solenoid length of 0.8 m, a toroid bending radius of 0.25 m and maximum magnetic field in the cooling section of 0.5 kG. The commissioning of the electron cooler was carried out with successful observation of both longitudinal and horizontal cooling of the proton beam. By varying the electric potential on the Pierce electrode in the gun, we have investigated the possibility of generating a hollow shaped electron beam, and studied its effect on the electron cooling process. Also the effect of the electrostatic deflector, installed in the toroid section in order to compensate the drift motion of the secondary electrons, was investigated. The design and results of the commissioning of the compact electron cooler are presented.  
 
TUPLS067 Status of the HESR Electron Cooler Design Work electron, antiproton, target, collider 1648
 
  • D. Reistad, T. Bergmark, O. Byström, B. Gålnander, S. Johnson, T. Johnson, T. Lofnes, G. Norman, T. Peterson, K. Rathsman, L. Westerberg
    TSL, Uppsala
  • H. Danared
    MSL, Stockholm
  The electron energy of the HESR electron cooler shall be variable from 450 keV to 4.5 MeV. Furthermore, the design shall not exclude a further upgrade to 8 MeV. Operation of the HESR in a collider mode, which requires electron cooling of both protons and antiprotons traveling in opposite directions, is an interesting option. The status of the technical design of the HESR electron cooling system will be presented.  
 
TUPLS068 LEIR Electron Cooler Status electron, ion, vacuum, injection 1651
 
  • G. Tranquille, V. Prieto, R. Sautier
    CERN, Geneva
  • A.V. Bubley, V.V. Parkhomchuk
    BINP SB RAS, Novosibirsk
  The electron cooler for LEIR is the first of a new generation of coolers being commissioned for fast phase space cooling of ion beams in storage rings. It is a state-of-the-art cooler incorporating all the recent developments in electron cooling technology (adiabatic expansion, electrostatic bend, variable density electron beam…) and is designed to deliver up to 600 mA of electron current for the cooling and stacking of Pb54+ ions in the frame of the ions for LHC project. In this paper we present our experience with the commissioning of the new device as well as the first results of ion beam cooling with a high-intensity variable-density electron beam.  
 
TUPLS069 Performance of Fermilab's 4.3 MeV Electron Cooler electron, antiproton, cathode, focusing 1654
 
  • A.V. Shemyakin, A.V. Burov, K. Carlson, M. Hu, T.K. Kroc, J.R. Leibfritz, S. Nagaitsev, L.R. Prost, S.M. Pruss, G.W. Saewert, C.W. Schmidt, M. Sutherland, V. Tupikov, A. Warner
    Fermilab, Batavia, Illinois
  A 4.3 MeV DC electron beam is used to cool longitudinally an antiproton beam in the Fermilab's Recycler ring. The cooling rate is regulated either by variation of the electron beam current up to 0.5 A or by a vertical separation of beams in the cooling section. The paper will describe steps that provided a stable operation and present the status of the cooler.  
 
TUPLS080 The Proposed 2 MeV Electron Cooler for COSY-Juelich electron, COSY, acceleration, target 1684
 
  • J. Dietrich
    FZJ, Jülich
  • V.V. Parkhomchuk
    BINP SB RAS, Novosibirsk
  The design, construction and installation of a 2 MeV electron cooling system for COSY-Juelich is proposed to further boost the luminosity even with strong heating effects of high-density internal targets. In addition the design of the 2 MeV electron cooler for COSY is intended to test some new features of the high energy electron cooler for HESR at FAIR/GSI. The design of the 2 MeV electron cooler will be accomplished in cooperation with the Budker Institute of Nuclear Physics in Novosibirsk, Russia. Starting with the boundary conditions of the existing electron cooler at COSY the requirements and a first general scheme of the 2 MeV electron cooler are described.  
 
WEPCH022 Study of the Effect of Multipolar Components in the SPARC Emittance Compensation Gun Solenoid emittance, quadrupole, multipole, cathode 1969
 
  • C. Ronsivalle, G. Dattoli, L. Picardi, M. Quattromini
    ENEA C.R. Frascati, Frascati (Roma)
  • G. Bazzano
    CNAO Foundation, Milan
  • M. Ferrario, M. Migliorati, L. Palumbo, M.A. Preger, C. Sanelli
    INFN/LNF, Frascati (Roma)
  • P. Musumeci
    INFN-Roma, Roma
  • J.B. Rosenzweig
    UCLA, Los Angeles, California
  The SPARC photoinjector rf gun requires a solenoid immediately downstream for emittance compensation. The analysis of the measured solenoid magnetic maps shows the existence of multipolar components added to the pure solenoid field. The effect of these added fields on beam dynamics and possible correction schemes have been studied from the theoretical point of view and by numerical calculations based on PARMELA/TREDI codes. An accurate 3D numerical modelization by using CST EM Studio has been done, in order to investigate the source of these multipolar components and to suggest some design modifications aimed to reduce their magnitude. The results of this study are presented here.  
 
WEPCH112 Database Extension for the Beam Dynamics Simulation Tool V-code quadrupole, simulation, electron, multipole 2176
 
  • W. Ackermann, W.F.O. Müller, B. Steiner, T. Weiland
    TEMF, Darmstadt
  • J. Enders, H.-D. Gräf, A. Richter
    TU Darmstadt, Darmstadt
  The beam dynamics simulation tool V-Code has been proved to be very useful in redesigning the injector layout at the superconducting linear accelerator in Darmstadt (S-DALINAC). Modifications in the beam optics are necessary because a new source of polarized electrons should be installed in addition to the existing thermionic gun. The calculations are performed with V-Code which is designed to handle a large amount of individual beam line elements and can therefore be used for extensive accelerator studies. The available database includes all the necessary components like solenoids, quadrupoles and rf cavities, but as a result of their consecutive treatment overlapping external fields are not allowed. Due to geometrical restrictions in the assembly of the new source a space-saving candidate of a quadrupole triplet violates this software-related condition if it is regarded as three distinct quadrupoles. Consequently, a more general beam line element has to be created which treats the lenses as a single unit without interference of their fields to attached cells. The indispensable data base extension together with simulation results and implementation verifications will be presented.  
 
WEPCH114 On the Development of a Self-consistent Particle-in-cell (PIC) Code Using a Time-adaptive Mesh Technique simulation, PITZ, DESY, ASTRA 2182
 
  • S. Schnepp, E. Gjonaj, T. Weiland
    TEMF, Darmstadt
  For a large class of problems the self-consistent simulation of charged particle beams in linear accelerators is necessary. Especially, in all low-energetic sections such as injectors the self-consistent interaction of particles and fields has to be taken into account. Well-known programs like the MAFIA TS Modules typically use the Particle-in-cell (PIC) method for beam dynamics simulations. Since they use a fixed computational grid which has to resolve the bunch adequately, they suffer from enormous memory consumption. Therefore and especially in the 3D case, only rather short sections can be simulated. A remedy to this limitation is the usage of a grid which refines itself in the vicinity of particles. For this purpose, a new code called SMOVE based on a time-adaptive grid is being developed. First promising results will be presented at the conference.  
 
WEPCH116 Recent Simulation Results of the Polarized Electron Injector (SPIN) of the S-DALINAC simulation, electron, quadrupole, MAMI 2188
 
  • B. Steiner, W.F.O. Müller, T. Weiland
    TEMF, Darmstadt
  • J. Enders, H.-D. Gräf, C. Heßler, G. Iancu, A. Richter, M. Roth
    TU Darmstadt, Darmstadt
  Recent design and development for a polarized electron source (SPIN) for the recirculating superconducting electron linear accelerator S-DALINAC will be presented. The polarized electron beam will be produced by photoemission from an InAlGaAs/GaAs superlattice cathode and will be accelerated to 100 kV electrostatically. The results of the beam dynamics simulation will be shown in detail. The start phase space of the electron bunch behind the gun has been approximated. The transverse focusing system consists of very short quadrupoles. Further main components of the new injector are a Wien filter, a Mott polarimeter, a chopper-prebuncher system (based on devices used at the Mainz Mikrotron MAMI), and diverse beam diagnostic tools. For the approximation of the start phase space CST MAFIA is used, and for the beam dynamic simulation VCode is used.  
 
WEPCH172 Electron Beam Pulse Processing toward the Intensity Modified Radiation Therapy (IMRT) electron, radiation, laser, cathode 2334
 
  • T. Kondoh, S. Tagawa, J. Yang, Y. Yoshida
    ISIR, Osaka
  Radiation therapy attracts attention as one of the cancer therapies nowadays. Toward the next generation of the intensity modified radiation therapy (IMRT), the processing of electron beam pulse is studied using a photo cathode RF gun linac. Accelerated electron pulses will be converted to x-ray pulses by a metal target bremsstrahlung method or by a laser inverse Compton scattering method. Recently, the radiation therapy of cancer is developing to un-uniform irradiation as IMRT. A photo cathode RF gun is able to generate a low emittance electron beam pulse using a laser light pulse. We thought that a photo cathode RF gun can generate intensity and shape modified electron beam by processing of incident laser light. Because of a low emittance, an electron pulse is able to accelerate keeping shape. Electron beam processing by photo masks in incident optical system and generated beams are reported here. Images on photo masks were transported to a cathode surface by optical relay imaging. Beams were monitored by Desmarquest (Cr:Al2O3) luminescence. Spatially separation of a spot to a spot is about 0.3mm. Modified electron beam has fine spatial resolution.  
 
WEPCH182 Design of 9.4 GHz 950 keV X-band Linac for Nondestructive Testing electron, linac, target, KEK 2358
 
  • T. Yamamoto, T. Natsui, M. Uesaka
    UTNL, Ibaraki
  • M. Akemoto, S. Fukuda, T. Higo, M. Yoshida
    KEK, Ibaraki
  • K. Dobashi
    The University of Tokyo, Nuclear Professional School, Ibaraki-ken
  • E. Tanabe
    AET Japan, Inc., Kawasaki-City
  Mobile "suit-case-sized" x-band (9.4GHz) 950 keV linac is designed for applications of nondestructive testing (NDT). Conventional device for the purpose is the S-band linac, but its drawback is a rather large device-size, large electron beam spot size of about 3 mm and lack of spatial resolution. We aim to realize the smaller spot size about 500 micro-m by a low emittance beam. The proposed system consists of the 9.4 GHz magnetron, modulator, thermionic RF electron gun and 9.4 GHz x-band linac and metal target for x-ray generation. The energy at the gun is 20 keV, and the final energy becomes 950 keV. Now, we are designing the linac structure of the pai/2 mode and analyzing the electromagnetic field (EMF) by SUPERFISH. At this time, we finish analyzing EMF of regular cavity cells and we are analyzing EMF of total accelerating tube. We have finished the detailed RF design. Further, we are also performing the design of the pai mode and going to discuss the advantages and drawbacks between them. Construction of the RF supplying system is underway. The detailed design parameters and updated status of the construction are presented at the spot.  
 
WEPCH188 Compact Picosecond Pulse Radiolysis System Using Photo-cathode RF Gun laser, electron, injection, emittance 2373
 
  • M. Washio, Y. Hama, Y. Kamiya, M. Kawaguchi, R. Moriyama, H. Nagai, K. Sakaue
    RISE, Tokyo
  • H. Hayano, J. Urakawa
    KEK, Ibaraki
  • S. Kashiwagi
    ISIR, Osaka
  • R. Kuroda
    AIST, Tsukuba, Ibaraki
  • K.U. Ushida
    RIKEN, Saitama
  A very compact picosecond pulse radiolysis system has been installed and operated at Waseda University. The system is composed of a laser photo-cathode RF gun as the pump source and stable Nd:YLF laser as the white light source to probe the reaction in the picosecond region. The white light generation is performed by the non-linear effect of intense laser light with the wavelength of 1047 nm into the water cell. The experimental results with the time resolution of 18 ps by examining the time profile of hydrated electron have been obtained. The system configuration will be also presented at the conference.  
 
WEPLS043 Progress of the Rossendorf SRF Gun Project ELBE, cathode, TESLA, vacuum 2469
 
  • D. Janssen, A. Arnold, H. Buettig, R. Hempel, U. Lehnert, P. Michel, K. Moeller, P. Murcek, Ch. Schneider, R. Schurig, F. Staufenbiel, J. Teichert, R. Xiang
    FZR, Dresden
  • T. Kamps, D. Lipka, F. Marhauser
    BESSY GmbH, Berlin
  • W.-D. Lehmann
    IfE, Dresden
  • J. Stephan
    IKST, Drsden
  • V. Volkov
    BINP SB RAS, Novosibirsk
  • I. Will
    MBI, Berlin
  In this paper we report the status and the progress of the superconducting RF gun project in Rossendorf. The gun is designed for cw operation mode with 1 mA current and 10 MeV electron energy. The cavity consists of three cells with TESLA geometry, a special designed half-cell in which the photo cathode will be inserted and a choke filter, which prevents the leakage of RF power by the coaxial line between the cathode and the cavity cell. A double tuner allows the tuning of the half-cell and the TESLA cells separately. In 2005 the fabrication of two cavities with RRR300 and RRR40 was finished. We present the results of the field measurement and the warm tuning of the cavity cells as well as the tuning and performance measurement of the choke filter. The fabrication of the double tuner has been also finished. In a test bench we measured the properties of the tuner (tuning range, resolution) at LN2 temperature. Further activities concern the diagnostic beam line of the gun, the new cathode preparation and cathode transfer system, the driver laser and the LHe transfer line.  
 
WEPLS044 Design of a Superconducting Cavity for a SRF Injector emittance, laser, cathode, electron 2472
 
  • D. Janssen
    FZR, Dresden
  • V. Volkov
    BINP SB RAS, Novosibirsk
  In a collaboration between BESSY, DESY, FZR, MBI and BINP a 3-1/2 cell superconducting RF electron gun is under development at the FZ - Rossendorf. The status of the project and the progress obtained in the last year is reported on this conference. The motivation for the design of a new gun cavity, presented in this paper, is the new FEL project at BESSY. This FEL is designed for a bunch charge of 2.5 nC and the transverse emittance should be comparable with that of the current SRF gun project. In order to compensate the high bunch charge a high electric field on the cavity axis is necessary. In the present paper we will present the design of a 1-1/2 cell cavity for a superconducting RF gun. The active length of the cavity (without beam tube) is 14.4 cm. For the magnetic peak field the conservative value of 130 mT is assumed. The obtained particle energy is 6.6 MeV, corresponding to an accelerating field strength of 45.6 MV/m . In the TESLA cavity the same magnetic peak field is connected with an accelerating field strength of approximately 31 MV/m. Tracking calculation of electron bunches are in progress and will be also reported.  
 
WEPLS047 3-1/2 Cell Superconducting RF Gun Simulations cathode, emittance, simulation, focusing 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.  
 
WEPLS049 The Design of a Hybrid Photoinjector for High Brightness Beam Applications simulation, coupling, emittance, bunching 2487
 
  • D. Alesini, M. Ferrario, V. Fusco, B. Spataro
    INFN/LNF, Frascati (Roma)
  • L. Ficcadenti, A. Mostacci, L. Palumbo
    Rome University La Sapienza, Roma
  • B. O'Shea, J.B. Rosenzweig, G. Travish
    UCLA, Los Angeles, California
  In this paper, we illustrate the electromagnetic and beam dynamics design procedure of a new class of photoinjector, a hybrid standing/traveling wave structure. In this device a standing wave RF gun section is integrated with a downstream traveling wave structure through a coupling cell that feeds simultaneously the two sections. We discuss the advantages in RF and beam performance of the hybrid photoinjector compared to conventional systems. The electromagnetic design has been performed using the 2D and 3D electromagnetic codes Superfish and HFSS. Results of beam dynamics simulations in different operating conditions are also discussed.  
 
WEPLS051 Dark Current Investigation of TTF and PITZ RF Guns cathode, PITZ, DESY, LEFT 2493
 
  • L. Monaco, P. Michelato, C. Pagani, P. Pierini, D. Sertore
    INFN/LASA, Segrate (MI)
  • J.H. Han, S. Schreiber
    DESY, Hamburg
  • M. Krasilnikov, F. Stephan
    DESY Zeuthen, Zeuthen
  The dark current is one of the limiting factor in the operation of RF guns at high gradient. The continuous request of higher brilliance sources and further emittance minimization, leads to apply higher gradients in the RF gun cavity, with the consequence of a significant dark current production. In this context we set up a collaborative effort to identify the dark current sources in the gun, in order to discriminate between the gun and cathode contribution. A critical analysis and organization of dark current measurements, taken during the operation of TTF and PITZ guns, with several cathodes operated at different accelerating fields and solenoids focusing, is presented. Potential areas of improvement are also discussed, together with a possible associated program.  
 
WEPLS052 High QE Photocathode at FLASH cathode, laser, vacuum, electron 2496
 
  • D. Sertore, P. Michelato, L. Monaco, C. Pagani
    INFN/LASA, Segrate (MI)
  • J.H. Han, S. Schreiber
    DESY, Hamburg
  The RF gun-based photoinjector of the VUV-FEL/TTF at DESY continues to use high quantum efficiency (QE) photocathodes produced at LASA, Milano. To study the photocathode behavior during beam operation, an online QE monitoring tool has been installed. In this paper, we present the hardware and software setup for the online QE measurement and the results so far obtained. The measured QEs are usually higher than at TTF phase 1. We compare the QE values taken in the RF gun with data measured just after production with a continuous UV light source.  
 
WEPLS053 RF Design of a Cartridge-type Photocathode RF Gun in S-band Linac linac, cathode, vacuum, simulation 2499
 
  • H. Moritani, Y. Muroya, A. Sakumi, T. Ueda, M. Uesaka
    UTNL, Ibaraki
  • H. Hanaki, N. Kumagai, S. Suzuki, H. Tomizawa
    JASRI/SPring-8, Hyogo-ken
  • J. Sasabe
    Hamamatsu Photonics K.K., Hamakita, Shizuoka
  • J. Urakawa
    KEK, Ibaraki
  A cartridge-type photocathode RF gun is under development in collaboration with SPring-8 and Hamamatsu Photonics. Each type of cathode (Cs2Te, Mg, diamond, Ag-Cs-O) is sealed in a cartridge-type vacuum tube. Several tubes can be installed in a vacuum chamber. The cathode in the tube is inserted into a center hole in the back plate of the RF gun by a vacuum manipulator. These cartridge-type photocathodes with high QE or sensitivity for visible lights, which are prepared in a factory, can be used for a long time without vacuum breaking. Since a load-lock system for forming a new high QE film is not needed, the cartridge-type RF gun becomes compact. We are going to introduce this cartridge-type system to our linac with the BNL-GUN-IV RF gun this summer. Now, we are calculating the gun parameters of the transmission cavity which has a back plate with a center hole 8mm in diameter with SUPERFISH and simulating the beam dynamics after modifying the beam line to install the system with PARMELA. We aim to use reliable Mg and high-QE Cs2Te and try diamond and Ag-Cs-O for radiation chemistry applications. The detailed numerical design and construction will be presented.  
 
WEPLS054 Higher-order Effect Compensation in Magnetic Compressor for < 50 fs Electron Bunch Generation electron, linac, simulation, quadrupole 2502
 
  • K. Kan, T. Kondoh, J. Yang, Y. Yoshida
    ISIR, Osaka
  An ultrashort electron bunch is essential for pulse radiolysis, which is a pump-probe measurement based on an ultrashort electron beam and an ultrashort light. In Osaka University, a laser photocathode electron linear accelerator with a magnetic compressor has been constructed for the femtosecond electron bunch generation. An electron beam with bunch length of 98 fs was successfully generated and used in pulse radiolysis. However, an electron beam with bunch length of < 50 fs is required for development of pulse radiolysis with time resolution of 100 fs. To generate such a short bunch, higher order disadvantage effects, which are caused by the fringing fields of the magnets in the compressor, should be compensated. In this paper, a compensation technique of higher-order effects was proposed by using a nonlinear energy modulation in the bunch produced in the linear accelerator by re-phasing the linac away from the zero-crossing of the rf (i.e., away from the linear slope). In the simulation, we compressed the electron bunch into 48 fs at bunch charge of 0.1 nC.  
 
WEPLS055 Development of Double-decker Electron Beam Accelerator for Femto/attosecond Pulse Radiolysis electron, linac, laser, emittance 2505
 
  • Y.K. Kuroda, T. Kondoh, J. Yang, Y. Yoshida
    ISIR, Osaka
  The study of electron-induced reactions in femto/attosecond time region is very important for the next electron beam nanofabrication. Pulse radiolysis with time resolution of sub-picosecond, as a powerful method to study such reactions in materials, has been developed by using radio-frequency electron accelerators and ultrashort lasers. In Osaka University, a new concept of double-decker electron beam accelerator is proposed for opening next pulse radiolysis on femto/attosecond time scale. The double electron beams with time delay of 1.4ns (350ps x 4) and bunch charge of 0.5-0.6 nC were generated in a photocathode electron accelerator by injecting two laser pulses into the photocathode. The beam energy of the two beams was 31.7MeV. The transverse normalized emittance was 3~6 mm-mrad for both the beams. The front of them is converted to Cherenkov light and used as a probe light source, and the back is used as a pump source. Both electron pulses are generated by one accelerator, resulting in no time jitter between the pump electron bunch and the probe laser pulse.  
 
WEPLS057 Equivalent Velocity Spectroscopy Based on Femtosecond Electron Beam Accelerator electron, laser, injection, linac 2511
 
  • S. Takemoto, T. Kondoh, J. Yang, Y. Yoshida
    ISIR, Osaka
  A new femtosecond pulse radiolysis system, which is called as "Equivalent Velocity Spectroscopy (EVS)" based on a photocathode rf linear accelerator and a femtosecond laser, is developed in ISIR for the study of primly process and ultrafast electron-induced reactions for the nanofabrication. In order to achieve a high time resolution on femtosecond scale, a femtosecond electron beam bunch produced by a photocathode accelerator and a synchronized femtosecond laser were used. The electron bunch and laser pulse were injected with an angle determined by the refractive index of the sample. The electron bunch was also rotated with a same angle, resulting in the time resolution degradation due to the velocity difference between light and the electron in the sample is thus avoided. A jitter compensation technique with a femtosecond streak camera was used to reduce the time jitter between the electron bunch and laser pulse. Moreover, in EVS, a technique of double laser pulse injection was used to improve the signal to noise ratio due to the fluctuation of the laser intensity during the measurement.  
 
WEPLS058 Femtosecond Single-bunch Electron Linear Accelerator Based on a Photocathode RF Gun electron, linac, laser, emittance 2514
 
  • J. Yang, K. Kan, T. Kondoh, A. Yoshida, Y. Yoshida
    ISIR, Osaka
  A femtosecond single-bunch electron linear accelerator based on a photocathode rf gun was developed in Osaka University for the study of radiation-induced ultrafast physical and chemical reactions. A 32 MeV single electron bunch with a bunch length of 98 fs in rms was generated successfully in the linear accelerator with a magnet bunch compressor. The dependences of the bunch length and the transverse emittance on the bunch charge were investigated experimentally and theoretically. The higher-order effects in the magnetic field were studied and compensated successfully by using a nonlinear energy-phase correlation in the bunch produced in the linear accelerator. By using the femtosecond electron bunch, an equivalent velocity spectroscopy with a synchronized femtosecond laser, as a new method with femtosecond time-resolution, was developed for study of the ultrafast reactions or phenomena on the femtosecond time scale.  
 
WEPLS059 The PHIN Photoinjector for the CTF3 Drive Beam laser, CTF3, CERN, vacuum 2517
 
  • R. Losito, H.-H. Braun, N. Champault, E. Chevallay, V. Fedosseev, A. Kumar, A.M. Masi, G. Suberlucq
    CERN, Geneva
  • G. Bienvenu, B.M. Mercier, C.P. Prevost, R. Roux
    LAL, Orsay
  • M. Divall, G.J. Hirst, G. Kurdi, W. E. Martin, I. O. Musgrave, I. N. Ross, E. L. Springate
    CCLRC/RAL, Chilton, Didcot, Oxon
  A new photoinjector for the CTF3 drive beam has been designed and is now being constructed by a collaboration among LAL, CCLRC and CERN within PHIN, the second Joint Research Activity of CARE. The photoinjector will provide a train of 2332 pulses at 1.5 GHz with a complex timing structure (sub-trains of 212 pulses spaced from one another by 333 ps or 999 ps) to allow the frequency multiplication scheme, which is one of the features of CLIC, to be tested in CTF3. Each pulse of 2.33 nC will be emitted by a Cs2Te photocathode deposited by a co-evaporation process to allow high quantum efficiency in operation (>3% for a minimum of 40 h). The 3 GHz, 2 1/2 cell RF gun has a 2 port coupler to minimize emittance growth due to asymmetric fields, racetrack profile of the irises and two solenoids to keep the emittance at the output below 20 pi.mm.mrad. The laser has to survive very high average powers both within the pulse train (15 kW) and overall (200 W before pulse slicing). Challenging targets are also for amplitude stability (<0.25% rms) and time jitter from pulse to pulse (<1ps rms). An offline test in a dedicated line is foreseen at CERN in 2007.  
 
THXPA03 Laser Systems and Accelerators laser, electron, FEL, undulator 2728
 
  • H. Schlarb
    DESY, Hamburg
  The presentation will cover the use of laser systems in accelerators. Topics covered will be the use of lasers for the production of electron beam from photocathodes, timing and diagnostics, laser heater systems to control space charge effects, as seed systems. Challenges in terms of stability, pulse shaping, power and pulse lengths, wavelength range and tuning will be covered for the various aspects.  
slides icon Transparencies
 
THYPA01 Overview of FEL Injectors emittance, brightness, laser, electron 2733
 
  • M. Ferrario
    INFN/LNF, Frascati (Roma)
  Future light sources based on high gain free electron lasers, require the production, acceleration and transport up to the undulator entrance of high brightness (low emittance, high peak current) electron bunches. Wake fields effects in accelerating sections and in magnetic bunch compressors typically contribute to emittance degradation, hence the photo-injector design and its operation is the leading edge for high quality beam production and for the success of the future light sources. RF guns, photo-cathode materials, laser pulse shaping and synchronization systems are evolving towards a mature technology to produce high quality and stable beams. Nevertheless reduction of thermal emittance, damping of emittance oscillations and bunch compression are still the main issues and challenges for injector designs. With the advent of Energy Recovery Linacs, superconducting RF guns have been also considered in many new projects as a possible electron source operating in CW mode. An overview of recent advancements and future perspectives in FEL injectors will be illustrated in this talk, including a comparison of merits and issues of RF compression versus magnetic compression techniques.  
slides icon Transparencies
 
THXFI01 State of the Art in EM Field Computation simulation, dipole, SLAC, TESLA 2763
 
  • C.-K. Ng, V. Akcelik, A.E. Candel, S. Chen, N.T. Folwell, L. Ge, A. Guetz, H. Jiang, A.C. Kabel, K. Ko, L. Lee, Z. Li, E.E. Prudencio, G.L. Schussman, R. Uplenchwar, L. Xiao
    SLAC, Menlo Park, California
  This presentation will provide an up-to-date survey of the methods and tools for the computation of electromagnetic fields in accelerator systems and components.  
slides icon Transparencies
 
THPCH151 Commissioning of the Laser System for SPARC Photoinjector laser, cathode, simulation, emittance 3146
 
  • C. Vicario, M. Bellaveglia, D. Filippetto, A. Gallo, G. Gatti, A. Ghigo
    INFN/LNF, Frascati (Roma)
  • P. Musumeci, M. Petrarca
    INFN-Roma, Roma
  In this paper we report the commissioning of the SPARC photoinjector laser system. In the high brightness photoinjector the quality of the electron beam is directly related to the features of the laser pulse. In fact the temporal pulse shape, the temporization and the transverse distribution of the electron beam is determined by the incoming laser pulse. The SPARC laser system is based on an amplified Ti:Sapphire active medium and the pulse shape is imposed by a programmable acousto-optics dispersive filter. The transfer-line has been designed to reduce the angular jitter and to preserve to the cathode the temporal and spatial features of the laser pulse. The laser system has been integrated with the accelerator apparatus. The diagnostics and the control system has been completed. We present the measured performances and the simulations we carried out.  
 
THPCH161 Status of the Polarized Electron Gun at the S-DALINAC electron, laser, cathode, quadrupole 3173
 
  • C. Heßler, M. Brunken, J. Enders, H.-D. Gräf, G. Iancu, Y. Poltoratska, M. Roth
    TU Darmstadt, Darmstadt
  • W. Ackermann, W.F.O. Müller, N. Somjit, B. Steiner, T. Weiland
    TEMF, Darmstadt
  • K. Aulenbacher
    IKP, Mainz
  Aiming at an extension of the experimenting capabilities for nuclear structure physics at low momentum transfer at the superconducting Darmstadt electron linear accelerator S-DALINAC, a polarized electron gun is being constructed. The new injector will be able to supply the S-DALINAC with 100 keV polarized electrons and should complement the present, unpolarized thermionic source. The design requirements are a degree of polarization of at least 80%, a mean current intensity of 0.06 mA and a 3 GHz cw structure. The basic design of the gun was adapted from the source of polarized electrons at MAMI, Mainz*, and optimized in various simulations. The active material is a strained layer GaAs crystal which is exposed to an 830 nm pulsed laser beam. We report on the status of the polarized source, the preparation setup and a test beam line.

*K. Aulenbacher et al., Nucl. Instrum. Meth. A 391, 498 (1997).

 
 
THPCH166 The Timing System for Diamond Light Source booster, DIAMOND, linac, controls 3182
 
  • Y.S. Chernousko, A. Gonias, M.T. Heron
    Diamond, Oxfordshire
  • T. Korhonen
    PSI, Villigen
  • E. Pietarinen, J. Pietarinen
    MRF, Helsinki
  The Diamond timing system is the latest generation development of the design, principles and technologies currently implemented in the Advanced Photon Source and Swiss Light Source timing systems. It provides the ability to generate reference events, distribute them over a fibre-optic network, and decode and process them at the equipment to be controlled. The timing system is closely integrated within the Diamond distributed control system, which is based on EPICS. The Diamond timing system functionality and performance, and first operational experiences in using the timing system during the commissioning of the accelerators, are presented in this paper.  
 
THPCH170 Reduction of Dark Current in SPring-8 Linac electron, linac, simulation, synchrotron 3194
 
  • T. Kobayashi, T. Asaka, H. Dewa, H. Hanaki, A. Mizuno, S. Suzuki, T. Taniuchi, H. Tomizawa, K. Yanagida
    JASRI/SPring-8, Hyogo-ken
  In the SPring-8 linac, removal of dark currents generated from an injector part has been studied to enhance the bunch purity of stored beam in the SPring-8 storage ring. We already succeeded in reduction of the dark currents from a thermionic electron gun by a beam deflector of parallel plate electrodes. However, dark currents are also generated in accelerating structures due to the high electric fields. We have been studying removal of the dark currents generated from the first accelerating structure by solenoid coils covering it.  
 
THPCH174 Multipactor Electron Gun with CVD Diamond Cathodes electron, DIAMOND, cathode, ion 3203
 
  • J.Y. Zhai, C.-X. Tang, S. Zheng
    TUB, Beijing
  A Multipactor Electron Gun (MEG) is developed for the high power microwave generation in the Accelerator Lab of Tsinghua University. This paper presents the recent experimental results of the S-band MEG using hydrogen-terminated and CsI-terminated CVD diamond cathodes. The gun design, cathode preparation and high power experiment are described. An electron beam with 5 μs macro-pulse, 10 Hz repetition rate, greater than 900 mA beam current was obtained.calculation and computer simulation. The properties of the secondary electron emission cathodes are also discussed.  
 
THPCH176 Deposition of Lead Thin Films Used as Photo-cathodes by Means of Cathodic Arc under UHV Conditions vacuum, plasma, cathode, ion 3209
 
  • P. Strzyzewski, J. Langner, M. S. Sadowski, J. Witkowski
    The Andrzej Soltan Institute for Nuclear Studies, Centre Swierk, Swierk/Otwock
  • T. Rao, J. Smedley
    BNL, Upton, Long Island, New York
  • R. Russo, S. Tazzari
    Università di Roma II Tor Vergata, Roma
  • J.S. Sekutowicz
    DESY, Hamburg
  The cathodic arc technology has been used for various technical purposes for many years. Recently, it has been demonstrated that the cathodic arc can be operated under ultra-high vacuum (UHV) conditions and it might solve the problem of the oxygen contamination coming from water remnants. It opens a new road to many applications where very pure metallic and/or superconducting films are needed. The paper reports on recent experimental studies aimed on the deposition of superconducting films of pure lead (Pb) by means of the UHV cathodic arc. Such layers can be used as photo-cathodes needed for modern accelerator injectors. The system configuration, used for thin film deposition inside the RF Gun designed at DESY, is also described and the main results and characteristics of thin superconducting Pb-films are presented.  
 
THPCH193 Comparison between H-ion and Heat Cleaning of Cu-metal Cathodes cathode, DIAMOND, GTF, LCLS 3245
 
  • D. Dowell, F. King, R.E. Kirby, J.F. Schmerge
    SLAC, Menlo Park, California
  Understanding the quantum efficiency (qe) of a metal photocathode in an s-band RF gun is important to limit the drive laser energy requirement and provide the best quality electron beam. Systematic measurements of the qe vs. wavelength for varying surface contamination have been performed on copper samples using x-ray photoelectron spectroscopy (XPS). The sample is first cleaned to the theoretical limit of qe using a 1 keV hydrogen ion beam. The H-ion beam cleans an area approximately 1cm in diameter and has no effect on the surface roughness while removing essentially all contaminants and lowering the work function to 4.3eV. The sample is then exposed to atmospheric contaminants (nitrogen and oxygen) and measured again with XPS to determine the degree of contamination and the effect on the qe. The goal is to determine the best procedure for transferring and installing cathodes in an s-band gun. These results and comparison with a heat cleaned cathode are presented.  
 
THPLS066 Improvement on the Single Bunch Operation of the TLS Injector electron, cathode, booster, linac 3439
 
  • J.-Y. Hwang, C.-S. Fann, K.-T. Hsu, S.Y. Hsu, K.H. Hu, S.H. Lee, K.-K. Lin, K.-B. Liu, Y.-C. Liu
    NSRRC, Hsinchu
  The improvement of the TLS (Taiwan Light Source) injector on single bunch operation is presented in this study. Limited by the existing design of the TLS injector, the single bunch operation was not optimized in terms of bunch purity for specific users of TLS. A high voltage pulser was implemented to improve the situation. This pulser has been integrated into the high-voltage-deck electronics of electron gun for single bunch generation. Both high-voltage pulses and the associated electron bunches are monitored with a wideband digital oscilloscope. The result shows that the bunch purity can be greatly improved by using the newly installed pulser. It also greatly eliminates the beam losses while injected into the booster ring.  
 
THPLS093 Status of the Photocathode RF Gun System at Tsinghua University laser, cathode, scattering, BNL 3496
 
  • X. He, Cheng. Cheng. Cheng, Q. Du, Du.Taibin. Du, Y.-C. Du, W.-H. Huang, Y. Lin, C.-X. Tang, S. Zheng
    TUB, Beijing
  An S-band high gradient photocathode RF gun test stand is in construction process at Tsinghua University. The photocathode RF gun test stand is a primary step of a femtosecond hard x-ray source based on Thomson scattering. The photocathode RF gun system adopts Ti:Sap laser, BNL IV type 1.6 cell RF gun, compact compensation solenoid. We foresee to conduct investigations on the thermal emittance contribution of surface roughness, the emittance compensation technique under various laser shape and its application to Thomson scattering x-ray source. Except for the transportation of laser, correction of laser front for glazing incidence and laser pulse shaping system, other parts of the photocathode RF gun test stand have been constructed, and we can start very primary experiment on the RF gun test stand, such as measurements of dark current, QE and energy of the beam. The experimental results are reported.  
 
THPLS094 First Measurement Results at the LEG Project's 100 keV DC Gun Test Stand emittance, diagnostics, cathode, SNR 3499
 
  • S.C. Leemann, Å. Andersson, R. Ganter, V. Schlott, A. Streun, A.F. Wrulich
    PSI, Villigen
  The Low Emittance Gun Project (LEG) at PSI aims at developing a high-brightness, high-current electron source: a 20-fold improved brightness compared to present state-of-the-art electron guns. The source is intended to form the basis for a cost-efficient implementation of a high-power X-ray FEL light-source for scientific research at PSI. A field emitter array (FEA) cathode is being considered a source candidate. In order to study pulsed field emission from such a cathode and to investigate space charge compensation techniques as well as to develop diagnostic procedures to characterize the beam resulting from an FEA cathode, a 100 keV DC gun test stand has been built. The test stand gun and diagnostics have been modeled with the codes MAFIA and GPT. From extensive parameter studies an optimized design has been derived and construction of the gun and diagnostics have recently been completed. We report on the commissioning of the test stand and present first measurement results.  
 
THPLS103 Investigations of the Longitudinal Phase Space at PITZ booster, PITZ, simulation, electron 3517
 
  • J.R. Roensch, J. Rossbach
    Uni HH, Hamburg
  • K. Abrahamyan, G. Asova, J.W. Baehr, G. Dimitrov, H.-J. Grabosch, J.H. Han, O. Kalekin, S. Khodyachykh, S.A. Korepanov, M. Krasilnikov, V. Miltchev, A. Oppelt, B. Petrosyan, S. Riemann, L. Staykov, F. Stephan
    DESY Zeuthen, Zeuthen
  • D. Lipka, R. Richter
    BESSY GmbH, Berlin
  The correlation between the positions of the particles in the bunch and their longitudinal momenta has to be analysed in order to optimize photo injectors for Free-Electron Lasers (FELs). Longitudinal phase space measurements at the upgraded PITZ facility* will be presented in this paper. Measurements of the complete longitudinal phase space and its projections behind the gun are compared with simulations. Momentum measurements after a booster cavity will be discussed.

*A.Oppelt et al. "Status and first results from the upgraded PITZ facility", FEL Conf. 2005.

 
 
THPLS104 Optimization Studies of the FERMI@ELETTRA Photoinjector emittance, laser, electron, cathode 3520
 
  • G. Penco, M. Trovo
    ELETTRA, Basovizza, Trieste
  • S.M. Lidia
    LBNL, Berkeley, California
  In the framework of the FERMI@ELETTRA project the electron beam characteristics strongly depend from the two operating modes: FEL1 (100nm-40nm) with a photon pulse around 100fs and FEL2 (40nm-10nm) with a long photon pulse (~1ps) having a high resolution spectral bandwidth. We present the multi-particles tracking code results concerning the photoinjector, which includes the RF gun and the first two accelerating sections, describing two possible electron bunch lengths, satisfying the two FEL operation modes. The injector optimization relative to the two options, aimed to produce a very low projected emittance (around 1 mm mrad) with a uniform behavior of the slice parameters (emittance and energy spread) along the bunch, is described in this paper. Moreover sensitivity studies, time and energy jitters estimations are presented for both cases.  
 
THPLS108 Performance Test of RF Photo-Cathode Gun at the PAL laser, emittance, electron, cathode 3529
 
  • J.H. Park, J.Y. Huang, C. Kim, I.S. Ko, Y.W. Parc, S.J. Park
    PAL, Pohang, Kyungbuk
  • X.J. Wang
    BNL, Upton, Long Island, New York
  A RF photo-cathode (RF PC) gun with 1.6 cell cavity is installed for the fs-FIR (Femto-second Far Infrared Radiation) facility being built at the Pohang Accelerator Laboratory (PAL). A short, intense, and low emittance electron beams are produced by the RF PC gun. Performance test of the gun is done include the measurement of RF chraterizations such as a resonant frequency, a mode separation, and etcs. The diagnostics of the beam according to the beam parameters such as phase, charge, and energy, and emittance are done. In this article, we present the measurement results of the RF charaterizations and the beam parameter diagnostics of the RF PC gun at the PAL.  
 
THPLS115 Simulation and Optimisation of a 100 mA DC Photo-Injector electron, emittance, cathode, ASTRA 3550
 
  • F.E. Hannon, C. Hernandez-Garcia
    Jefferson Lab, Newport News, Virginia
  A prototype 100mA injector is presently being designed and manufactured jointly between Thomas Jefferson National Accelerator Facility (J-Lab) and Advanced Energy Systems (AES). This paper discusses the physics optimisation and performance of the injector, which has been studied using the space-charge tracking code ASTRA. The objective is to operate the 7MeV injector with 135pC electron bunches at 748.5MHz repetition rate. We show that the longitudinal and transverse electron bunch properties can be realised within the constraints of the design.