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MOOCH02 First Full Beam Loading Operation with the CTF3 Linac linac, beam-loading, acceleration, instrumentation 39
 
  • R. Corsini, H.-H. Braun, G. Carron, O. Forstner, G. Geschonke, E. Jensen, L. Rinolfi, D. Schulte, F. Tecker, L. Thorndahl
    CERN, Geneva
  • M. Bernard, G. Bienvenu, T. Garvey, R. Roux
    LAL, Orsay
  • A. Ferrari
    Uppsala University, Uppsala
  • L. Groening
    GSI, Darmstadt
  • R.F. Koontz, R.H. Miller, R.D. Ruth, A.D. Yeremian
    SLAC, Menlo Park, California
  • T. Lefevre
    NU, Evanston
  The aim of the CLIC Study is to investigate the feasibility of a high luminosity, multi-TeV linear e+e- collider. CLIC is based on a two-beam method, in which a high current drive beam is decelerated to produce 30 GHz RF power needed for high-gradient acceleration of the main beam running parallel to it. To demonstrate the outstanding feasibility issues of the scheme a new CLIC Test Facility, CTF3, is being constructed at CERN by an international collaboration. In its final configuration CTF3 will consist of a 150 MeV drive beam linac followed by a 42 m long delay loop and an 84 m combiner ring. The installation will include a 30 GHz high power test stand, a representative CLIC module and a test decelerator. The first part of the linac was installed and commissioned with beam in 2003. The first issue addressed was the generation and acceleration of a high-current drive beam in the "full beam loading" condition where RF power is converted into beam power with an efficiency of more than 90%. The full beam loading operation was successfully demonstrated with the nominal beam current of 3.5 A. A variety of beam measurements have been performed, showing good agreement with expectations.  
Video of talk
Transparencies
 
MOPKF005 Preliminary Results on a Low Emittance Gun Based on Field Emission electron, cathode, emittance, free-electron-laser 306
 
  • R. Ganter, A.E. Candel, M. Dehler, G.J. Gobrecht, C. Gough, S.C. Leemann, K.L. Li, M. Paraliev, M. Pedrozzi, J.-Y. Raguin, L. Rivkin, V. Schlott, L. Schulz, A. Streun, A. Wrulich
    PSI, Villigen
  The development of a new electron gun with the lowest possible emittance would help reducing the total length and cost of a free electron laser. Recent progresses in vacuum nanoelectronics make field emitter arrays (FEAs) an attractive technology to explore for high brightness sources. Indeed, several thousands of microscopic tips can be deposited on a 1 mm diameter area. Electrons are then extracted by a first grid layer close to tip apex and focused by a second grid layer one micrometer above the tip apex. The typical aperture diameter of this focusing layer is also in the range of one micrometer. The big challenge with FEA, is to achieve good emission homogeneity, we hope to achieve this with diverse conditioning techniques. However if we can achieve a low emittance with FEAs another challenge will be to preserve the emittance during the beam acceleration.  
 
MOPKF009 Photoinjector Studies for the BESSY Soft X-ray FEL emittance, linac, focusing, electron 315
 
  • F. Marhauser
    BESSY GmbH, Berlin
  A linac driven soft X-Ray FEL facility has been proposed at BESSY with the aim to produce high brilliance photon beams within the energy range of 20eV to 1keV. The driver linac is based on superconducting (sc) L-Band rf-technolgy to enable cw operation of the FEL. As the electron beam emittance directly influence the photon beam characteristics, transverse slice emittances of 1.5pimmmrad are envisaged as a target goal. This demands for a high brilliance laser driven photoinjector rf-gun as electron source. For the first years of operation it is intended to use well known normal conducting (nc) L-Band rf-gun technology thereby restricting the macropulse repetition rate to 1 kHz to cope with the thermal power dissipation. At a later stage the nc rf-gun shall be replaced by a sc rf-gun, which is favoured conceptually as it allows to generate outmost flexible bunch patterns according to the needs of the experiments by fully exploiting the capabilities of the sc linac. This paper details the design considerations for a high power nc rf-gun complemented by results of beam dynamic studies up to the exit of the booster linac using ASTRA. Perspectives for the use of a sc photoinjector gun cavity are addressed.  
 
MOPKF013 The Influence of the Main Coupler Field on the Transverse Emittance of a Superconducting RF Gun emittance, electron, linac, pick-up 327
 
  • D. Janssen
    FZR, Dresden
  • M. Dohlus
    DESY, Hamburg
  For the Rossendorf superconducting RF gun project the influence of the additional RF field, created in the cavity by the RF power flow at the main coupler, is discussed. One end of the gun cavity is occupied by the cathode insert, so all flanges are concentrated on the other end. In the "flange plane" of the cavity two HOM coupler, the pic up and the main coupler are located. If we normalize the RF field in the cavity by the condition Eacc = 25MV/m and assume a beam power of 10kW (CW mode), we obtain an quality factor Qext = 2.2*10**7. A three dimensional field calculation using the MAFIA code, gives the field perturbation near the main coupler. Tracking calculation with ASTRA show,that this perturbation increases the transversel emittance between 1 and 4%, nearly independent from the bunch charge. This result shows, that for average beam powers in the vicinity of 10kW effects, connected with the assymetric input of RF power can be neglected.  
 
MOPKF014 Emittance Compensation of a Superconducting RF Photoelectron Gun by a Magnetic RF Field emittance, cathode, superconducting-RF, electron 330
 
  • D. Janssen
    FZR, Dresden
  • V. Volkov
    BINP SB RAS, Novosibirsk
  For compensation of transverse emittance in normal conducting RF photoelectron guns a static magnetic field is applied. In superconducting RF guns the application of a static magnetic field is impossible. Therefore we put instead of a static field a magnetic RF field (TE - mode) together with the corresponding accelerating mode into the superconducting cavity of the RF gun. For a 3 _ cell cavity of the superconducting gun with frequencies f = 1.3GHz for the accelerating mode and f = 3.9 GHz for the magnetic mode and a bunch charge of 1 nC a transversal emittance of 0.5 mm mrad has been obtained. In this case the maximal field strength on the axis were Ez = 50 MV/m for the accelerating mode and Bz = 0.34 T for the magnetic mode.(This corresponds to Bs(max) = 0.22T on the surface of the cavity). Possibilities for the technical realization (input of RF power for the TE mode, tuning of two frequencies in one cavity, phase stability) are discussed.  
 
MOPKF015 A Superconducting Photo-Injector with 3+1/2- Cell Cavity for the ELBE Linac cathode, laser, electron, pick-up 333
 
  • J. Teichert, H. Buettig, P. Evtushenko, D. Janssen, U. Lehnert, P. Michel, Ch. Schneider
    FZR, Dresden
  • W.-D. Lehmann
    IfE, Dresden
  • J. Stephan
    IKST, Drsden
  • V. Volkov
    BINP SB RAS, Novosibirsk
  • I. Will
    MBI, Berlin
  After successful tests of an SRF gun with a superconducting half-cell cavity [*], a new SRF photo-injector for CW operation at the ELBE linac has been designed. In this report the design layout of the SRF photo-injector, the parameters of the superconducting cavity and the expected electron beam parameters are presented. The SRF gun has a 31/2-cell niobium cavity working at 1.3 MHz and will be operated at 2 K. The three full cells have TESLA-like shapes. In the half-cell the photocathode is situated which will be cooled by liquid nitrogen.

* D. Janssen et. al., First operation of a superconducting RF-gun, Nucl. Instr. and Meth. A507(2003)314

 
 
MOPKF016 S2E Simulations on Jitter for European XFEL Project linac, simulation, emittance, klystron 336
 
  • Y. Kim, Y. Kim, D. Son
    CHEP, Daegu
  • K. Floettmann, T. Limberg
    DESY, Hamburg
  In order to generate stable 0.1 nm wavelength SASE source at the European X-ray laser project XFEL, we should supply high quality electron beams with constant beam characteristics to a 200 m long undulator. Generally, beam parameters such as peak current and energy spread are significantly dependent on jitter or error in RF phase and RF amplitude of superconducting accelerating modules, and magnetic field error of bunch compressors. In this paper, we describe the start-to-end simulations from the cathode to the end of linac to determine the jitter and error tolerances for the European XFEL project.  
 
MOPKF018 Injector and Bunch Compressor for the European XFEL Project emittance, linac, space-charge, simulation 342
 
  • Y. Kim, Y. Kim, D. Son
    CHEP, Daegu
  • M. Dohlus, K. Floettmann, T. Limberg
    DESY, Hamburg
  For the proper operation of European XFEL project, we should supply high quality electron beams with low emittance, short bunch length, and low energy spread to a 200 m long undulator. In this paper, we describe the optimization and design concepts of the XFEL injector and bunch compressors to control the beam parameter dilution due to the microbunching instability and CSR.  
 
MOPKF021 Properties of Cathodes Used in the Photoinjector RF Gun at the DESY VUV-FEL cathode, laser, vacuum, insertion 348
 
  • S. Schreiber
    DESY, Hamburg
  • J.H. Han
    DESY Zeuthen, Zeuthen
  • P. Michelato, L. Monaco, D. Sertore
    INFN/LASA, Segrate (MI)
  The new injector of the DESY VUV-FEL is being commissioned in spring 2004. Several cathodes have been tested in the photoinjector RF Gun. We report on quantum efficiency, dark current, and the overall appearance of the cathodes after their use.  
 
MOPKF022 Commissioning of the VUV-FEL Injector at TTF emittance, laser, electron, simulation 351
 
  • S. Schreiber
    DESY, Hamburg
  The VUV-FEL at the TESLA Test Facility (TTF) at DESY is being upgraded to an FEL user facility serving high brilliance beams in the wavelength range from the VUV to soft X-rays. The photoinjector has been redesigned to meet the more demanding beam parameters in terms of transverse emittance, peak current, and energy spread. The first phase of the injector upgrade has been finished in spring 2004. We report on its commissioning, including first measurements of beam parameters.  
 
MOPKF026 Conditioning and High Power Test of the RF Guns at PITZ cathode, electron, vacuum, klystron 357
 
  • J.H. Han, K. Abrahamyan, J. Bähr, H.-J. Grabosch, M. Krasilnikov, D. Lipka, V. Miltchev, A. Oppelt, B. Petrosyan, D. Pose, L. Staykov, F. Stephan
    DESY Zeuthen, Zeuthen
  • I. Bohnet, J.-P. Carneiro, K. Floettmann, S. Schreiber
    DESY, Hamburg
  • M.V. Hartrott, R. Richter
    BESSY GmbH, Berlin
  • P. Michelato, L. Monaco, D. Sertore
    INFN/LASA, Segrate (MI)
  This paper describes the recent results of conditioning and high power tests of the photocathode RF guns at the Photo Injector Test Facility at DESY Zeuthen (PITZ). For successful operation of high gain SASE FELs, high phase space density of the electron beam is required. A high gradient in the gun has to be applied to improve the quality of the space charge dominated beams. In addition, long RF pulses and high repetition rate should be achieved to provide a high average power of FEL radiation. The first PITZ RF gun has been successfully tested at a mean power of 27 kW (900μseconds, 10 Hz, and 3 MW) and has been installed at the VUV-FEL at DESY Hamburg. Another RF gun has been installed at PITZ in January 2004 and is being conditioned for high power tests. The dark current behavior for various cathodes and for all operating schemes is also presented.  
 
MOPKF030 "ARC-EN-CIEL" a Proposal for a 4th Generation Light Source in France laser, radiation, electron, linac 366
 
  • M.-E. Couprie, D. Garzella, B. Gilquin, P. Monot, L. Nahon
    CEA/DSM, Gif-sur-Yvette
  • O.V. Chubar, A. Loulergue
    SOLEIL, Gif-sur-Yvette
  • M. Desmons, M. Jablonka, F. Meot, A. Mosnier
    CEA/DSM/DAPNIA, Gif-sur-Yvette
  • J.-R. Marquès
    LULI, Palaiseaux
  • J.-M. Ortega
    LURE, Orsay
  • A. Rousse
    LOA, Palaiseau
  An accelerator based 4th generation source is proposed to provide the user community with coherent femtosecond light pulses in the UV to X ray range. The project is based on a CW 700 MeV superconducting linac delivering high charge, subpicosecond, low emittance electron bunches with high repetition rate. This facility allows for testing High Gain Harmonic Generation seeded with high harmonics in gases, as well as the standard SASE mode, covering a spectral range down to 0.8 nm and 5 nm respectively. In addition, two beam loops are foreseen to increase the beam current in using the energy recovery technique. They will accommodate undulators for the production of femtosecond synchrotron radiation in the IR, VUV and X ray ranges together with a FEL oscillator in the 10 nm range.  
 
MOPKF041 SPARC Photoinjector Working Point Optimization, Tolerances and Sensitivity to Errors emittance, undulator, simulation, linac 396
 
  • M. Ferrario, M.E. Biagini, M. Boscolo, V. Fusco, S. Guiducci, M.  Migliorati, C. Sanelli, F. Tazzioli, C. Vaccarezza
    INFN/LNF, Frascati (Roma)
  • L. Giannessi, L. Mezi, M. Quattromini, C. Ronsivalle
    ENEA C.R. Frascati, Frascati (Roma)
  • J. Rosenzweig
    UCLA, Los Angeles, California
  • L. Serafini
    INFN-Milano, Milano
  A new optimization of the SPARC photoinjector, aiming to reduce the FEL saturation length, is presented in this paper. Start to end simulations show that with 1.1 nC charge in a 10 ps long bunch we can deliver at the undulator entrance a beam having 100 A in 50% of the slices (each slice being 300 mm long) with a slice emittance ?1 mm, thus reducing the FEL-SASE saturation length to 12 m at 500 nm wavelength. In addition the stability of the nominal working point and its sensitivity to various type of random errors, under realistic conditions of the SPARC photoinjector operation, are discussed. A systematic scan of the main parameters around the operating point, performed with PARMELA code interfaced to MATLAB, shows that the probability to get a projected emittance exceeding 1 mm is only 10 % and the slice emittance remains below 1 mm in all cases.  
 
MOPKF042 Status of the SPARC Project laser, undulator, emittance, linac 399
 
  • M. Ferrario, D. Alesini, M. Bellaveglia, S. Bertolucci, M.E. Biagini, R. Boni, M. Boscolo, M. Castellano, A. Clozza, G. Di Pirro, A. Drago, A. Esposito, D. Filippetto, V. Fusco, A. Gallo, A. Ghigo, S. Guiducci, M. Incurvati, C. Ligi, F. Marcellini, 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, M. Mauri
    INFN/LASA, Segrate (MI)
  • I. Boscolo, F. Brogli, S. Cialdi, C. De Martinis, D. Giove, C. Maroli, V. Petrillo, M. Romé, L. Serafini
    INFN-Milano, Milano
  • L. Catani, E.C. Chiadroni, A. Cianchi, S. Tazzari
    Università di Roma II Tor Vergata, Roma
  • F. Ciocci, G. Dattoli, A. Doria, F. Flora, G.P. Gallerano, L. Giannessi, E. Giovenale, G. Messina, L. Mezi, P.L. Ottaviani, L. Picardi, M. Quattromini, A. Renieri, C. Ronsivalle
    ENEA C.R. Frascati, Frascati (Roma)
  • D. Dowell, P. Emma, C. Limborg-Deprey, D. Palmer
    SLAC, Menlo Park, California
  • D. Levi, M. Mattioli, G. Medici
    Università di Roma I La Sapienza, Roma
  • M.  Migliorati, A. Mostacci, L. Palumbo
    Rome University La Sapienza, Roma
  • P. Musumeci, J. Rosenzweig
    UCLA, Los Angeles, California
  • M. Nisoli, S. Stagira, S. de Silvestri
    Politecnico/Milano, Milano
  The aim of the SPARC project is to promote an R&D activity oriented to the development of a high brightness photoinjector to drive SASE-FEL experiments at 500 nm and higher harmonics generation. It has been proposed by a collaboration among ENEA-INFN-CNR-Universita‘ di Roma Tor Vergata-INFM-ST and funded by the Italian Government with a 3 year time schedule. The machine will be installed at LNF, inside an existing underground bunker. It is comprised of an rf gun driven by a Ti:Sa laser to produce 10-ps flat top pulses on the photocathode, injecting into three SLAC accelerating sections. We foresee conducting investigations on the emittance correction and on the rf compression techniques up to kA level. The SPARC photoinjector can be used also to investigate beam physics issues like surface-roughness-induced wake fields, bunch-length measurements in the sub-ps range, emittance degradation in magnetic compressors due to CSR. We present in this paper the status of the design activities of the injector and of the undulator. The first test on diagnostic prototypes and the first experimental achievements of the flat top laser pulse production are also discussed.  
 
MOPKF043 An Ultra-high Brightness, High Duty Factor, Superconducting RF Photoinjector emittance, brightness, electron, simulation 402
 
  • M. Ferrario
    INFN/LNF, Frascati (Roma)
  • J. Rosenzweig
    UCLA, Los Angeles, California
  • J. Sekutowicz
    DESY, Hamburg
  Recent advances in superconducting rf technology, and an improved understanding of rf photoinjector design optimization make if possible to propose a specific design for a superconducting rf gun which can simultaneously produce both ultra-high peak brightness, and high average current. Such a device may prove to be a critical component of next generation x-ray sources such as self-amplified spontaneous emission free-electron lasers (SASE FEL) and energy recovery linac (ERL) based systems. The design presented is scaled from the present state-of-the-art normal conducting rf photoinjector that has been studied in the context of the LCLS SASE FEL. Issues specific to the superconducing rf photoinjector, such as accelerating gradient limit, rf cavity design, and compatibility with magnetic focusing and laser excitation of a photocathode, are discussed.  
 
MOPKF045 Cesium Telluride and Metals Photoelectron Thermal Emittance Measurements Using a Time-of-flight Spectrometer emittance, electron, laser, cathode 408
 
  • D. Sertore, D. Favia, P. Michelato, L. Monaco, P. Pierini
    INFN/LASA, Segrate (MI)
  The thermal emittance of photoemitted electrons in an RF gun is a crucial parameter for short wavelength FELs and future high luminosity electron colliders. An estimate of the thermal emittance of semiconductor and metal samples, commonly used as photocathodes, has been assessed using a Time-Of-Flight spectrometer. In this paper we present the analysis, based on angle resolved photoemission measurements, of both the cesium telluride (Cs2Te) photocathode films as used at the TESLA Test Facility, and polycrystalline metals. These latter measurements, at different laser wavelengths, are used to validate both our experimental apparatus and the thermal emittance reconstruction technique developed.  
 
MOPKF046 Photoelectron RF Gun Designed as a Single Cell Cavity linac, emittance, cathode, electron 411
 
  • H. Dewa, T. Asaka, H. Hanaki, T. Kobayashi, A. Mizuno, S. Suzuki, T. Taniuchi, H. Tomizawa, K. Yanagida
    JASRI/SPring-8, Hyogo
  • J. Sasabe
    Hamamatsu Photonics K.K., Hamakita, Shizuoka
  • M. Uesaka
    UTNL, Ibaraki
  The paper describes the recent improvements of S-band RF-gun at SPring-8. The cavity of the gun is a single-cell pillbox, and the copper inner wall is used as a cathode. The electron beam from the cathode was accelerated up to 4.1 MeV at an electric field of 175 MV/m. For emittance compensation, two solenoid magnets were used. A 3m linac and a quadrupole scan emittance diagnostic were added after the RF-gun. The beam energy spread and beam emittance after the linac is presented. The beam emittance measured with quadrupole scan is compered to that measured with double slits just after the RF-gun. For high quantum efficiency, Cs2Te cathode was also tested. It is vacuum sealed in a cartridge-type electric tube and four tubes can be installed in a vacuum chamber behind the cavity. Although the quantum efficiency after RF conditioning for two hours to achieve 90MV/m was 3%, it decreased to 1% after the 28 hours RF conditioning.  
 
MOPKF063 4GLS and the Prototype Energy Recovery Linac Project at Daresbury linac, electron, booster, brightness 455
 
  • M.W. Poole, E.A. Seddon
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  The 4GLS project is a novel next generation solution for a UK national light source proposed to be sited at Daresbury. It is based on an energy recovery linac (ERL) operating at high average beam currents up to 100mA and with compression schemes producing pulses in the 10-100 fs range. This would provide a unique spontaneous emission source with high average brightness output both from undulators and bending magnets. In addition to this operating regime a high peak current mode would also be possible at lower duty cycle, enabling a high gain FEL amplifier to generate XUV radiation. Longer wavelength FELs are also planned. This challenging accelerator technology, new to Europe, necessitates a significant R&D programme and as a major part of this a low energy prototype, the ERLP, is being constructed at Daresbury. The paper summarises the ERLP design specification, describes the component solutions adopted and explains the 4GLS project status and plans.  
 
MOPKF067 Comparison of Different Buncher Cavity Designs for the 4GLS ERLP linac, higher-order-mode, emittance, space-charge 467
 
  • E. Wooldridge, C.D. Beard, C. Gerth
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • A. Buechner
    FZR/FWFE, Dresden
  A DC photocathode gun is part of the injector of the Energy Recovery Linac Prototype (ERLP) currently built at Daresbury Laboratory. A buncher is required for the ERLP to decrease the bunch length off the gun. Three different single-cell cavity designs were investigated: The Cornell buncher, the Elbe Buncher and an EU cavity without Higher Order Mode (HOM) dampers. The properties of these cavities were studied with the computer codes CST's Microwave Studio and ASTRA. The fundamental frequency and field pattern was investigated in Microwave Studio. The EU cavity had to be scaled from 500MHz as the required frequency for the buncher is 1.3GHz. As the anticipated kinetic energy of the electron beam after the gun is about 350keV a particle tracking code including the space charge forces is mandatory to study the effect of the different buncher cavity designs on the beam dynamics. The particle tracking code ASTRA was used to study the performance of the bunchers for a variety of beam parameters. From these investigations it was found that the three bunchers produce very similar effects on the particle bunch.  
 
MOPKF070 Design of Injector Systems for LUX emittance, linac, cathode, quadrupole 476
 
  • S.M. Lidia
    LBNL/AFR, Berkeley, California
  The LUX concept [1] for a superconducting recirculating linac based ultrafast x-ray facility features a unique high-brightness electron beam injector. The design of the injector complex that meets the baseline requirements for LUX are presented. A dual-rf gun injector provides both high-brightness electron beams to drive the cascaded, seeded harmonic generation VUV-soft x-ray FELs as well as the ultra- low-vertical emittance ('flat') beams that radiate in hard x-ray spontaneous emission synchrotron beamlines. Details of the injector complex design and performance characteristics are presented. Contributions by the thermal emittance and optical pulse shaping to the beam emission at the photocathode and to the beam dynamics throughout the injector are presented. Techniques that seek to optimize the injector performance, as well as constraints that prevent straightforward optimization, are discussed.  
 
MOPKF079 The Linac Coherent Light Source Photo-Injector Overview and Some Design Details cathode, linac, emittance, dipole 500
 
  • D. Dowell, R. Akre, L.D. Bentson, P. Bolton, R.M. Boyce, R. Carr, J.E. Clendenin, S.M. Gierman, A. Gilevich, K. Kotturi, Z. Li, C. Limborg-Deprey, W. Linebarger, M. Ortega, J. Schmerge, P. Smith, L. Xiao
    SLAC, Menlo Park, California
  The Linac Coherent Light Source (LCLS)[*] is a SASE free electron laser using the last 1/3 of the SLAC two mile linac to produce 1.5 to 15 angstrom x-rays in a 100 meter long undulator. A new 135 MeV photo-injector will be built in an existing, off-axis vault at the 2/3 point of the main linac. The injector accelerator consists of a BNL/SLAC/UCLA s-band gun followed by two 3-meter long SLAC accelerator sections. The 5.6 MeV beam from the gun is matched into the first accelerator section and accelerated to 135 MeV before injection onto the main linac axis with a 35 degree bend [**]. Several modifications have been made to the rf gun, linac and beamline as well as the inclusion of several diagnostics have been incorporated into the injector design to achieve the required 1.2 micron projected emittance at a charge of 1 nC. In addition, a laser heater [***], will increase the uncorrelated energy spread to suppress coherent synchrotron radiation and longitudinal space charge instabilities in the main accelerator and bunch compressors [****]. The configuration and function of the major injector components will be described.

* Linac Coherent Light Source (LCLS) CDR No. SLAC-R-593 UC-414, 2002 ** C. Limborg et al., Proc. of the 2003 International FEL Conf *** R. Carr et al, Contrib. to these proceedings **** Z. Huang et al., Contrib. to these proceedings

 
 
MOPKF083 Inverse Free Electron Laser Heater for the LCLS laser, electron, undulator, linac 512
 
  • R. Carr, L.D. Bentson, P. Bolton, D. Dowell, P. Emma, A. Gilevich, Z. Huang, J.J. Welch, J. Wu
    SLAC, Menlo Park, California
  The LCLS Free Electron Laser employs an RF photocathode gun that yields a 1 nC charge bunch a few picoseconds long, which must be further compressed to yield the high current required for SASE gain. The very cold electron beam from the RF photocathode gun is quite sensitive to microbunching instabilities such as coherent synchrotron radiation (CSR) in the compressor chicanes and longitudinal space charge (LSC) in the linac. These effects can be Landau damped by adding energy spread to the electron bunch prior to compression. We propose to do this by interacting an infrared laser beam with the electron bunch in an undulator added to the LCLS gun-to-linac injector. The undulator is placed in a 4-bend chicane to allow the IR laser beam to propagate co-linearly with the e-beam while it oscillates in the undulator. The IR laser beam is derived from the photocathode gun laser. Simulations presented elsewhere in these proceedings show that the laser interaction damps the microbunching instabilities to a very great extent. This paper is a description of the implementation of the laser heater  
 
MOPKF085 Design Optimizations of X-ray FEL Facility at MIT linac, electron, laser, simulation 518
 
  • D. Wang, M. Farkhondeh, W. Graves, J. Van der Laan, F. Wang, T. Zwart
    MIT/BLAC, Middleton, Massachusetts
  • P. Emma
    SLAC, Menlo Park, California
  MIT is exploring the construction of a linac-based x-ray laser user facility on the campus of the Bates Linear Accelerator Center. The facility under consideration would span the wavelength range from 100 to 0.3 nm in the fundamental, move into the hard X-ray region in the third harmonic, and preserve the possibility of an upgrade to even shorter wavelengths. The accelerator configuration would include a high brightness electron gun, a superconducting electron linac and multiple undulators and beam lines to support a growing user community. This paper will present the recent progress on the start-to-end simulations including the parameter optimizations and sensativity analysis.  
 
MOPKF086 Modifications of the LCLS Photoinjector Beamline emittance, laser, quadrupole, linac 521
 
  • C. Limborg-Deprey, D. Dowell, S.M. Gierman
    SLAC, Menlo Park, California
  The LCLS Photoinjector beamline is now in the Design and Engineering stage. The fabrication and installation of this beamline is scheduled for the summer 2006. The Photoinjector will deliver 10 ps long electron bunches of 1nC with a normalized transverse emittance of less than 1 mm.mrad for 80% of the slices constituting the core of the bunch at 135 MeV. In this paper, we describe some modifications of the beamline: new exit energy, additional focusing, insertion of a laser heater. We also describe an alternate tuning which is based on a laser pulse of 20ps. The advantages and drawbacks of this long pulse tuning are reviewed. A comparison of sensitivity to field errors and misalignment between the long pulse tuning and the nominal tuning is given.  
 
MOPLT054 High Current Operation of Pre-bunching Cavities in the CTF3 Accelerator beam-loading, coupling, simulation, klystron 674
 
  • R. Roux, G. Bienvenu
    LAL, Orsay
  • E. Jensen
    CERN, Geneva
  In the framework of the CLIC studies for a 3 TeV centre of mass linear collider the CLIC Test Facility-3 accelerator (CTF3) is developed to validate the novel concept of CLIC drive beam generation. The front end of the CTF3 linac uses a 140 kV thermionic gun capable to deliver a beam with currents of up to 10 A during 1.5 microseconds. Theμtime structure of this beam is generated with two standing wave single-cell 3 GHz pre-buncher cavities. The high current demands special care in the design of the pre-bunchers to preserve beam quality and transmission. A particular concern was beamloading in the second pre-buncher. In this paper, the design and the conditioning of the pre-bunchers are reported but the main focus is on the commissioning with the electron beam, which showed unexpected results. Indeed, contrary to our expectations, the unbunched beam seems to induce a kind of beamloading in the first pre-buncher while the second one shows none.  
 
MOPLT101 Performances of the Beam Generated by Metal-Dielectric Cathodes in RF Electron Guns cathode, electron, plasma, acceleration 767
 
  • I.V. Khodak, I.V. Khodak, V.A. Kushnir
    NSC/KIPT, Kharkov
  The paper describes results of the experimental research of the metal-dielectric cathode operation in RF electron gun. Application of these cathodes permits RF guns to generate intense beams with nanosecond current pulse duration. Electron beam is extracted from plasma sheath developed during the surface vacuum flashover dielectric. Simulated and experimental parameters of the beam obtained at the single-cavity RF gun output are summarized in the paper. The beam formation and its interaction with microwave field of high strength are analyzed qualitatively. Results are compared with experimental results obtained before in the 1.5-cavity RF electron gun. First experimental results on electron beam generation by the RF gun with a ferroelectric cathode are discussed in the paper.  
 
MOPLT111 On using NEA Cathodes in an RF Gun electron, ion, cathode, vacuum 797
 
  • M. Huening
    Fermilab, Batavia, Illinois
  RF guns have been proven to deliver high brightness beams and therefore appear attractive as electron source for a linear collider. Only so far no polarized beams have been produced. To create a polarized electron beam GaAs NEA cathodes are used. Operating rf guns with a NEA cathode poses concerns in three areas, oxidation by residual gas, ion bombardment, and electron bombardment. In this paper we report about an attempt to reduce the vacuum pressure inside the gun by cooling it to cryogenic temperatures. Furthermore the energy deposition by ions and electrons will be quantified.  
 
MOPLT156 High Brightness Electron Guns for Next-Generation Light Sources and Accelerators electron, cathode, emittance, linac 899
 
  • H. Bluem, M.D. Cole, J. Rathke, T. Schultheiss, A.M.M. Todd
    AES, Princeton, New Jersey
  • I. Ben-Zvi, T. Srinivasan-Rao
    BNL, Upton, Long Island, New York
  • P. Colestock, D.C. Nguyen, R.L. Wood, L. Young
    LANL, Los Alamos, New Mexico
  • D. Janssen
    FZR, Dresden
  • J. Lewellen
    ANL, Argonne, Illinois
  • G. Neil, H.L. Phillips, J.P. Preble
    Jefferson Lab, Newport News, Virginia
  Advanced Energy Systems continues to develop advanced electron gun and injector concepts. Several of these projects have been previously described, but the progress and status of each will be updated. The project closest to completion is an all superconducting RF (SRF) gun, being developed in collaboration with the Brookhaven National Laboratory, that uses the niobium of the cavity wall itself as the photocathode material. This gun has been fabricated and will shortly be tested with beam. The cavity string for a closely-coupled DC gun and SRF cavity injector that is expected to provide beam quality sufficient for proposed ERL light sources and FELs will be assembled at the Jefferson Laboratory later this year. We are also collaboration with Los Alamos on a prototype CW normal-conducting RF gun with similar performance, that will undergo thermal testing in late 2004. Another CW SRF gun project that uses a high quantum efficiency photocathode, similar to the FZ-Rossendorf approach, has just begun. Finally, we will present the RF design and cold test results for a fully axisymmetric, ultra-high-brightness x-band RF gun.  
 
TUYBCH02 Technological Challenges for High Brightness Photo-injectors laser, electron, vacuum, brightness 64
 
  • G. Suberlucq
    CERN, Geneva
  Many applications, from linear colliders to free-electron lasers, passing through light sources and many other electron sources, require high brightness electron beams, usually produced by photo-injectors. Because certain parameters of these applications differ by several orders of magnitude, various solutions were implemented for the design and construction of the three main parts of the photo-injectors: lasers, photocathodes and guns. This paper summarizes the different requirements, how they lead to technological challenges and how R&D programs try to overcome these challenges. Some examples of state-of-the-art parts are presented.  
Video of talk
Transparencies
 
TUPKF017 Electrons Beam Dynamics of the 100 MeV Preinjector Helios for the SOLEIL Synchrotron linac, emittance, electron, focusing 997
 
  • A.S. Setty
    THALES, Colombes
  A 100 MeV electron linac is under construction, in order to inject into the booster synchrotron of SOLEIL. The linac is designed to work according to two operation modes : a short pulse mode (2 ns - 0,5 nC) and a long pulse mode (300 ns - 8 nC). Calculation of the beam dynamics, using our selfmade code PRODYN, has been carried out from the gun to the end of the linac. Special care has been taken on the gun design to avoid an overfocusing outcoming beam in order to obtain a final low emittance. Calculations results are given.  
 
TUPKF051 A 500 kV Power System for a Gridded Sheet-beam Klystron klystron, impedance, cathode, power-supply 1066
 
  • M.A. Kempkes, F.O. Arntz, J.A. Casey, M.P.J. Gaudreau, N. Reinhardt, R.P. Torti
    Diversified Technologies, Inc., Bedford
  The Next Generation Linear Collider (NLC) will require hundreds of X-band high power klystrons. These klystrons are typically cathode pulsed at 500 kV and 265 A each, with 1.6 microsecond pulses of RF, and a complex microwave delay line to achieve 400 ns RF pulses. Because the pulsed voltage is so high, CV2f losses will lead to many millions of dollars per year of wasted power. The klystron group at SLAC, working with Calabazas Creek Research (CCR), is developing a gridded, sheet beam klystron. This new klystron design avoids the CV2 losses of cathode pulsing because its cathode is not pulsed - it remains at a constant high voltage. Instead, the grid voltage is pulsed over a much smaller (6 kV) voltage range. This paper will describe DTI's progress in development of the electronics required to drive this new klystron, including a 500 kV multiplier power supply and grid modulator, a multi-concentric high voltage cable, which also acts as the pulse forming line, and an advanced, reentrant cable connection to the klystron itself. This design allows the klystron to be located adjacent to the beamline, and separated from the power electronics, improving RF efficiency, maintainability, and overall reliability.  
 
TUPKF055 Space-charge-limited Magnetron Injection Guns for Gyroklystrons cathode, simulation, injection, electron 1072
 
  • W. Lawson
    Maryland University, College Park, Maryland
  We present the results of several space-charge-limited (SCL) magnetron injection gun (MIG) designs which are intended for use with a 500 kV, 500 A gyroklystron with accelerator applications. The design performances are compared to that of a temperature-limited (TL) gun that was constructed for the same application. The SCL designs yield similar values for beam quality, namely an axial velocity spread under 3% for an average perpendicular-to-parallel velocity ratio of 1.5. The peak electric fields and the cathode loadings of the SCL designs are somewhat higher than for the TL design. Three designs are described in this paper. In the first design the space-charge limit is achieved by recessing the emitter into the cathode. The other two designs have control electrodes to which a voltage can be applied to change the beam current independently of the beam voltage. One of these designs can accept a bias sufficiently high to cut off the current completely, so that a DC power supply with pulsed grid operation is possible. Details of all designs as well as a discussion of the advantages and disadvantages of the SCL designs as compared to the TL design will be given.  
 
TUPKF063 Current Status of the Next Linear Collider X-band Klystron Development Program klystron, vacuum, focusing, collider 1090
 
  • D.W. Sprehn, G. Caryotakis, A.A. Haase, E.N. Jongewaard, C. Pearson
    SLAC, Menlo Park, California
  Klystrons capable of driving accelerator sections in the Next Linear Collider have been developed at SLAC during the last decade. In addition to fourteen 50 MW solenoid-focused devices and a 50 MW Periodic Permanent Magnet focused (PPM) klystron, a 500 kV 75 MW PPM klystron was tested in 1999 to 80 MW with 3-microsecond pulses, but very low duty. Subsequent 75 MW prototypes aimed for low-cost manufacture by employing reusable focusing structures external to the vacuum, similar to a solenoid electromagnet. During the PPM klystron development, several partners (CPI, EEV and Toshiba) have participated by constructing partial or complete PPM klystrons. After early failures during testing of the first two devices, SLAC has recently tested this design (XP3-3) to the full NLC specifications of 75 MW, 1.6 microseconds pulse length, and 120 Hz. This 14.4 kW operation came with a tube efficiency of 50%. The XP3 3 average and peak output power, together with the focusing method, arguably makes it the most advanced high power klystron ever built anywhere in the world. Design considerations and the latest testing results for these latest prototypes will be presented.  
 
TUPKF066 34 Ghz, 45 MW Pulsed Magnicon: First Results electron, plasma, cathode, linear-collider 1096
 
  • O.A. Nezhevenko, V.P. Yakovlev
    Omega-P, Inc., New Haven, Connecticut
  • J.L. Hirshfield, M.A. LaPointe
    Yale University, Physics Department, New Haven, CT
  A high efficiency, high power magnicon at 34.272 GHz has been designed and built as a microwave source to develop RF technology for a future multi-TeV electron-positron linear collider. To develop this technology, this new RF source is being perfected for necessary tests of accelerating structures, RF pulse compressors, RF components, and to determine limits of breakdown and metal fatigue. After preliminary RF conditioning of only about 200000 pulses, the magnicon produced an output power of 10.5 MW in 0.25 microsecond pulses, with a gain of 54 dB. Slotted line measurements confirmed that the output was monochromatic to within a margin of at least 30 dB.  
 
TUPKF067 High Power Magnicons at Decimeter Wavelength for Muon and Electron-Positron Colliders collider, electron, linac, acceleration 1099
 
  • O.A. Nezhevenko, V.P. Yakovlev
    Omega-P, Inc., New Haven, Connecticut
  • J.L. Hirshfield
    Yale University, Physics Department, New Haven, CT
  The CLIC drive linac requires pulsed RF amplifiers with a power of 50 MW at 937 MHz. In turn the muon collider requires 100 MW, 800 MHz RF amplifiers for the final stages of acceleration. In this paper conceptual designs of magnicons for these applications are presented. In addition to the typical magnicon advantages in power and efficiency, the designs offers substantially shorter tube length compared to either single- or multiple-beam klystrons.  
 
TUPKF075 Inductive Output Tubes for Particle Accelerators electron, microtron, feedback, background 1111
 
  • H.P. Bohlen
    CPI, Palo Alto, California
  • E. Davies, P. Krzeminski, Y. Li, R.N. Tornoe
    CPI/EIMAC, San Carlos, California
  The Inductive Output Tube (IOT) is not widely used as an RF power source in particle accelerators yet, but this is about to change rapidly. One reason for this change is the IOT's "coming of age": almost twenty years of successful operation in television transmitters have lead to high refinement of IOT technology and proven reliability. The other reason is the fitness of the IOT to especially meet accelerator requirements: high efficiency, no need for power back-off to achieve fast feed-back regulation, and the possibility to pulse the RF without using a high-voltage modulator. Two classes of IOTs are available so far for application in particle accelerators. One of them consists of UHF external-cavity devices, frequency-tunable and producing output power levels up to 80 kW CW. The second class has been developed only recently. These are L-band IOTs with internal output cavities for 1.3 and 1.5 GHz, respectively, featuring output power levels between 15 and 30 kW CW. Extensive computer simulations have lead to the conclusion that even higher-power IOTs, such as a 300 kW peak-power, long-pulse L-band tube, are feasible.  
 
TUPKF076 Large Scale Production of 805-MHz Pulsed Klystrons for SNS klystron, cathode, electron, simulation 1114
 
  • S. Lenci, E. Eisen
    CPI, Palo Alto, California
  The Spallation Neutron Source (SNS) is an accelerator-based neutron source being built in Oak Ridge, Tennessee, by the U.S. Department of Energy. The SNS will provide the most intense pulsed neutron beams in the world for scientific research and industrial development. CPI is supporting the effort by providing 81 pulsed klystrons for the super-conducting portion of the accelerator. The primary output power requirements are 550 kW peak, 49.5 kW average at 805 MHz, with an electron beam-to-rf conversion efficiency of 65% and an rf gain of 50 dB. Through January 2004, 47 units have been factory-tested. Performance specifications, computer model predictions, operating results, and production statistics will be presented.  
 
TUPKF077 Test Results for a 10-MW, L-band, Multiple-beam Klystron for TESLA klystron, electron, focusing, cathode 1117
 
  • E.L. Wright, A. Balkcum, H.P. Bohlen, M. Cattelino, L. Cox, E. Eisen, F. Friedlander, S. Lenci, A. Staprans, B. Stockwell, L. Zitelli
    CPI, Palo Alto, California
  • K. Eppley
    SAIC, Burlington, Massachusetts
  The VKL-8301 high-efficiency, multiple-beam klystron (MBK), has been developed for the DESY Tera Electron volt Superconducting Linear Accelerator (TESLA) in Hamburg, Germany. The first prototype is built and will be tested in March of 2004. The prototype has been designed for long-life operation by utilizing the benefits inherent in higher-order mode (HM) MBKs. The primary benefit of HM-MBKs is their ability to widely separate individual cathodes. One of the major obstacles to the success of this approach is the design of the off-axis electron beam focusing system, particularly when confined-flow focusing is desired. We will show simulated and measured data which demonstrates a solution to this problem. High power test results will also be shown.  
 
TUPLT001 Beam Dynamics in 100 MeV S-Band Linac for CANDLE linac, emittance, bunching, electron 1129
 
  • B. Grigoryan, V.M. Tsakanov
    CANDLE, Yerevan
  The report presents the results of the beam dynamics study in 100 MeV S-band linear accelerator foreseen as an injector for the CANDLE light source. An impact of the excited longitudinal and transverse wake fields on the particle energy spread and the beam transverse emittance are given.  
 
TUPLT074 Dark Current Reduction System for SPring-8 Linac linac, single-bunch, storage-ring, synchrotron 1324
 
  • T. Kobayashi, T. Asaka, H. Hanaki, M. Shoji, S. Suzuki, K. Tamura
    JASRI/SPring-8, Hyogo
  The SPring-8 linac accelerates dark currents generated by its injector part up to 1 GeV. These dark currents are injected with main beam into the SPring-8 storage ring and then spoil the purity of the stored beam. The dark currents are mainly composed of a grid emission current from a thermionic gun and field emission currents from rf accelerating structures. A beam deflector for kicking only the grid emission by a pulsed electric field was developed and installed in the SPring-8 linac. We observed that the beam deflector greatly reduced the grid emission current accelerated up to 1 GeV. The measured purity of the stored single-bunched beam was about 5x10-6 when the deflector operated, which was almost 1/100 of the purity without filtering by the deflector. However, the deflector, which is installed before the prebucher, cannot reduced the field emission currents from the buncher cavities and the first acccelerating structure. These dark currents take considerable proportion of the total dark currents observed at the end of the linac. We are trying to spin off the field emission currents by weak magnetic fields across the accelerating structure generated by several coils.  
 
TUPLT082 Generation of a Femtosecond Electron Beam for Nanoscience and Nanotechnology electron, laser, linac, emittance 1348
 
  • J. Yang, T. Kozawa, S. Tagawa, Y. Yoshida
    ISIR, Osaka
  A new S-band femtosecond electron linear accelerator was developed in Osaka University for the study of radiation-induced ultrafast physical and chemical reactions in femtosecond time regions. The femtosecond electron accelerator was constructed with a laser driven photocathode RF gun, a linear accelerator (linac) and a magnetic pulse compressor. The RF gun was driven by a mode-locked Nd:YLF picosecond laser. The electron beam produced by the RF gun was accelerated in the linac with energy modulattion by adjusted the RF phase. The magnetic pulse compression, which was constructed with two 45o-bending magnets and four quadrupole magnets, is a technique to longitudinally focus a charged beam by rotating the phase space distribution in a magnetic field. The picosecond electron pulse, which was generated in the RF gun and accelerated in the linac with energy modulation, was compressed into femtosecond by adjusted the quadrupole magnetic fields. The femtosecond electron pulse is expected for the studies of ultrafast reactions in nano-space.  
 
TUPLT086 A 40MeV Electron Source with a Photocathode for X-ray Generation through Laser-compton Scattering electron, laser, linac, emittance 1354
 
  • F. Sakai, N. Nakajyo, Y. Okada, T. Yanagida, M. Yorozu
    SHI, Tokyo
  .3 keV femtosecond X-ray generation through laser-Compton scattering with 14MeV electron source and a TW Ti:sapphire laser was achieved. In order to increase the X-ray energy up to 15 keV for some applications, e.g. protein crystallography, we modified the system to increase electron energy. Electron beams emitted from a S-band RF photocathode are accelerated up to 40MeV with two 1.5m standing-wave linacs. The beams are bended at 90 degree using an achromatic bending system, then focused with a triplet quadrupole-magnet to be interacted with laser pulses. The characteristics of electron beams, emittance, energy and energy dispersion, will be described.  
 
TUPLT120 Commissioning of Electron Cooler EC-300 electron, ion, cathode, vacuum 1419
 
  • V.B. Reva, E.A. Bekhtenev, V.N. Bocharov, A.V. Bubley, Y. Evtushenko, A.D. Goncharov, A.V. Ivanov, V.I. Kokoulin, V.V. Kolmogorov, M.N. Kondaurov, S.G. Konstantinov, V.R. Kozak, G.S. Krainov, Ya.G. Kruchkov, E.A. Kuper, A.S. Medvedko, L.A. Mironenko, V.M. Panasyuk, V.V. Parkhomchuk, K.K. Schreiner, B.A. Skarbo, A.N. Skrinsky, B.M. Smirnov, M.A. Vedenev, R. Voskoboinikov, M.N. Zakhvatkin, N.P. Zapiatkin
    BINP SB RAS, Novosibirsk
  • J. Li, W. Lu, L.J. Mao, Z.X. Wang, X.B. Yan, X.D. Yang, J.H. Zhang, W. Zhang, H.W. Zhao
    IMP, Lanzhou
  The article deals with the commissioning of electron cooler EC-300. It was designed and manufactured for CSR experiment (IMP, Lanzhou, China) by BINP, Russia. The energy of electron beam is up to 300 keV, the electron current is up to 3 A, the magnetic field in the cooling section is up to 1.5 kG. The major innovation of the cooler is the variable profile of electron beam, the electrostatic bends of the electron beam and the system of the magnetic field correction. During commissioning the linearity of the magnetic field 10-6 was obtained, the recuperation efficiency was observed up 10-6 , the pressure of residual gas in the vacuum chamber was 5? 10-11 torr during operation with the electron beam. The CSRe cooler for IMP is a new step at cooling technique and the first results achieved during commissioning are very interesting for accelerator physics.  
 
TUPLT164 CEBAF Injector Achieved World's Best Beam Quality for Three Simultaneous Beams with a Wide Range of Bunch Charges laser, space-charge, electron, cathode 1512
 
  • R. Kazimi, K. Beard, F.J. Benesch, A. Freyberger, J.M. Grames, T. Hiatt, A. Hutton, G.A. Krafft, L. Merminga, M. Poelker, M. Spata, M. Tiefenback, B.C. Yunn, Y. Zhang
    Jefferson Lab, Newport News, Virginia
  The CEBAF accelerator simultaneously provides three 499 MHz interleaved continuous electron beams spanning 5 decades in beam intensity (a few nA to 200 uA) to three experimental halls. The typical three-user physics program became more challenging when a new experiment, G0, was approved for more than six times higher bunch charge than is routine. The G0 experiment requires up to 8 million electrons per bunch (at a reduced repetition rate of 31 MHz) while the lowest current hall operates at 100 electrons per bunch simultaneously. This means a bunch destined to one hall may experience significant space charge forces while the next bunch, for another hall, is well below the space charge limit. This disparity in beam intensity is to be attained while maintaining best ever values in the beam quality, including final relative energy spread (<2.5x 10-5 rms) and transverse emittance (<1 mm-mrad norm. rms). The difficulties related to space charge emerge in the 10m long, 100 keV section of the CEBAF injector during initial beam production and acceleration. A series of changes were introduced in the CEBAF injector to meet the new requirements, including changes in the injector setup, adding new magnets, replacing lasers used for the photocathode and modifying typical laser parameters, stabilizing RF systems, and changes to standard operating procedures. In this paper, we will discuss all these modifications in some detail including the excellent agreement between the experimental results and detailed simulations. We will also present some of our operational results.  
 
THOACH02 Commissioning of the 500 MeV Injector for MAX-lab linac, electron, storage-ring, injection 219
 
  • S. Werin, Å. Andersson, M. Bergqvist, M. Brandin, M. Demirkan, M. Eriksson, L.-J. Lindgren, L. Malmgren, H. Tarawneh, E.J. Wallén
    MAX-lab, Lund
  • B. Anderberg
    AMACC, Uppsala
  • G. Georgsson
    Danfysik A/S, Jyllinge
  • G. LeBlanc
    ASP, Melbourne
  A 500 MeV new injector system for the storage rings MAX I, II and III have been installed during the winter 2003-4 at MAX-lab. The system consists of two linacs at 125 MeV each, using SLED, and a recirculating system such that the electrons pass the linacs twice, thus reaching a final energy of 500 MeV. The system is injected by a thermionic RF-gun. The commissioning of the complete system will be performed in the spring 2004.  
Video of talk
Transparencies
 
THPKF039 Study of Photo-cathode RF Gun for a High Brightness Electron Beam cathode, laser, electron, injection 2362
 
  • Y. Yamazaki
    JNC/OEC, Ibaraki-ken
  • S. Araki, H. Hayano, M. Kuriki, T. Muto, N. Terunuma, J. Urakawa
    KEK, Ibaraki
  • M.K. Fukuda, K. Hirano, M. Nomura, M. Takano
    NIRS, Chiba-shi
  We are going to develop a compact high-brightness electron beam system to adopt industrial and medical applications. A multi-bunch photo-cathode RF gun has been developed to generate 100 bunches beam with 2.8ns spacing and 5nC charge per bunch. We will report details of the development, especially photo-cathode production and emission characteristics from cathode by the laser.  
 
THPKF040 Development of a Femtosecond Pulse Radiolysis for Reaction Analysis in Nano-space laser, electron, ion, linac 2365
 
  • Y. Yoshida, T. Kozawa, S. Tagawa, J. Yang
    ISIR, Osaka
  A new femtosecond pulseradiolysis system was developed in Osaka University for the study of radiation-induced ultrafast physical and chemical reactions in femtosecond time regions. In the pulseradiolysis system, a femtosecond electron beam produced by a photocathode RF gun is used as an irradiation source, while a mode-locked Ti:Sapphire femtosecond laser was used as a probe light source. A time jitter between the electron pulse and the femtosecond laser was compensated by a jitter compensation technique used a femtosecond streak camera. An oblique incidence of the probe light is considered in the system to reduce the degradation of velocity difference between the electron and the laser light in samples. A time resolution of <100 fs is expected in the pulse radiolysis system for the analysis of utrafast physical and chemical reactions in nano-space.  
 
THPKF044 The Improvement of NSRRC Linac for Top-up Mode Operation electron, linac, storage-ring, power-supply 2374
 
  • J.-Y. Hwang, J. Chen, J.-P. Chiou, K.-T. Hsu, S.Y. Hsu, K.H. Hu, T.C. King, C.H. Kuo, K.-K. Lin, C.-J. Wang, Y.-T. Yang
    NSRRC, Hsinchu
  • C.T. Pan
    NTHU, Hsinchu
  The performance of the 50 MeV linac at the National Synchrotron Radiation Research Center (NSRRC) was examined and has been improved recently. The major improved items were 1) adopting a command-charging scheme to replace the resonance charging for the linac modulator; and 2) gun electronics. As a result, the beam quality was improved in terms of its energy spectrum and stability. The correlation between the improvement of beam quality and component upgrading is analyzed. The influence of the beam quality improvement to the recently proposed top-up mode operation in 2005 will also be discussed in this report.  
 
THPKF058 Experimental Experience with a Thermionic RF-gun cathode, emittance, electron, quadrupole 2394
 
  • S. Werin, Å. Andersson, M. Bergqvist, M. Brandin, L. Malmgren, S. Werin
    MAX-lab, Lund
  • G. Georgsson
    Danfysik A/S, Jyllinge
  An RF-gun structure developed at MAX-lab, and thus different from the most common BNL-structure, is in operation as a thermionic RF-gun at MAX-lab. The properties of the gun have been investigated. Especially aspects such as extractable energy range, emittance properties at various beamloading conditions and extracted current.  
 
THPKF059 Adaption of an RF-gun from Thermionic to Photo Cathode laser, cathode, injection, electron 2397
 
  • S. Werin, M. Berglund, M. Brandin, T. Hansen
    MAX-lab, Lund
  The current electron source for the injector at MAX-lab is a thermionic RF-gun. This gun produces a several ns long pulse with a significant beamloading. To allow for ?few bucket? operation and emittance reduction the gun will be adapted for operation with a ns laser system. The system to be installed during the spring 2004 is a 3 or 4th harmonic injection seeded Nd:YAG laser. The thermionic BaO cathode already in use will be used at a temperature just below thermal emission where a quantum efficiency of around 1* 10-4 is expected.  
 
THPLT018 Electron Beam Dynamics Simulations for the Low Emittance Gun emittance, simulation, cathode, electron 2505
 
  • M. Dehler, S.C. Leemann
    PSI, Villigen
  • A.E. Candel
    ETH, Zürich
  We report on theoretical simulation performed for the development of a high brightness, field emitter based electron gun suitable for an Angstrom wavelength free electron laser\cite{LEG}. First simulations have been done with available codes in 2 1/2D and 3D for basic gun configurations showing the global and local (due to the granularity of the emitter array) effects on the emittance dilution.Design and construction started on a test setup consisting of a 100 keV electron gun with solenoidal focusing and a diagnostics module. In addition to solenoid focussing, anode shaping will be investigated in order to compensate for non-linear fields leading to space charge blow-up. For advanced simulations of field emitter based guns allowing to resolve individual emitters and to capture the influence of mechanical imperfections, a massive parallel code for 3D particle-in-cell simulations is in development. The electromagnetic field solver is fully functional and the particle tracker has been completed in its basic structures.  
 
THPLT034 Implementation of Higher Order Moments for Beam Dynamics Simulation with the V-Code simulation, space-charge, emittance, laser 2553
 
  • W. Ackermann, T. Weiland
    TEMF, Darmstadt
  Based on the moment approach V-Code is implemented to simulate charged particle beam dynamics in linear accelerators. Its main aim is to perform elementary studies in those cases when the beam can be considered as a whole and thus making the motion of individual particles negligible in the overall view. Therefore an ensemble of particles can be well described by the moments of its phase-space distribution and the regarded order influences naturally the achievable accuracy as well as the computational effort. Since the well known moment equations generally are not closed, a technique to limit the number of involved moments has to be applied. So far all moments up to the second order have been considered whereas higher order moments are truncated. As a further step towards higher accuracy the influence of higher order moments has to be investigated. For this reason additional third-order equations are implemented into the V-Code and the achieved results are compared with previous second-order-based ones as well as with higher order approximations.  
 
THPLT035 Development of a 3D-Gun-Code based on a Charge Conserving Algorithm simulation, electron, cathode, space-charge 2556
 
  • E. Gjonaj, J. Mudiganti, T. Weiland
    TEMF, Darmstadt
  Recent efforts in the development of electron sources are aiming at high intensity electron beams, beyond the limitations posed by space-charge effects in conventional guns. Field emitter arrays, multi-beam and sheet-beam guns are a few examples of emerging technology, which require an accurate characterization of the limiting current in complicated 3D-geometry. The newly developed gun code at the Technische Universität Darmstadt, implements a novel approach to the numerical simulation of space-charge-limited electron emission, which is based on the local conservation of charge for arbitrary cathode surfaces. It is shown that, imposing exact charge conservation using the CAD-data of the geometry eliminates the spurious oscillations in the charge density, which typically arise when the piecewise-planar diode approximation is applied in the simulation. The accuracy of this approach is demonstrated in the validation study of a spherical diode and in the large-scale simulation of a Traveling Wave Tube amplifier.  
 
THPLT061 Development of a Multibunch Photo-cathode RF Gun System laser, cathode, injection, electron 2628
 
  • J. Urakawa, M. Akemoto, S. Araki, H. Hayano, M. Kuriki, T. Muto, N. Terunuma, Y. Yamazaki
    KEK, Ibaraki
  • M.K. Fukuda, K. Hirano, M. Nomura, M. Takano
    NIRS, Chiba-shi
  A multibunch photo-cathode RF gun system has been developed as a electron source for the production of quasi-monoenergetic X-rays based on inverse Compton scattering. This system consists of a photocathode rf gun, a cathode system, a laser system, beam diagnostic sections, and beam dump line. The gun produces 100 bunches with a 2.8ns bunch spacing and 5nC bunch charge. We will report on the RF gun system with 4 bending dipoles of a chicane which makes the laser injection to the cathode with perpendicular angle possible.  
 
THPLT080 Simulation Study of the Beam Loading Effect in an RF Gun simulation, laser, emittance, beam-loading 2682
 
  • K. Shinto, H. Hama, F. Hinode, A. Miyamoto, T. Tanaka
    LNS, Sendai
  Because of simple structure and apparatus, a thermionic rf gun has been considered to be employed in a new pre-injector for the future synchrotron radiation facility at Tohoku University. A 3-D beam simulation code for the rf gun using a Finite Difference Time Domain (FDTD) method to solve Maxwell's equations has been developed. In the rf gun, especially in case of the high beam current, electromagnetic fields induced by the electron beam are considered to affect beam characteristics such as beam emittance and energy spread. In the FDTD method, because the Maxwell?s equations are able to be solved including the term of current density of the charge, the electromagnetic fields produced by both the external rf power and the electron beam can be anticipated. Using the simulation code, beam loading effects on the characteristics of the electron beam extracted from the rf gun is investigated.  
 
THPLT081 Present Status of Photo-cathode RF Gun System and its Applications at Waseda University laser, electron, scattering, emittance 2685
 
  • R. Kuroda, Y. Hama, K. Hidume, H. Hirama, M. Kawaguchi, N. Kudo, T. Kuribayasi, S. Minamiguchi, R. Moriyama, T. Saito, K. Sakaue, D. Ueyama, M. Washio
    RISE, Tokyo
  • H. Hayano, J. Urakawa
    KEK, Ibaraki
  • S. Kashiwagi
    ISIR, Osaka
  • X.J. Wang
    BNL/NSLS, Upton, Long Island, New York
  High quality electron beam generation using photo-cathode rf gun system and its application have been developed at Waseda University. This system can generate about 4 MeV low emittance electron beam. This is applied for soft X-ray generation using laser Compton scattering and pulse radiolysis experiments based on the pump-probe technique. In case of the soft X-ray generation, Compton scattering experiments between about 4.2 MeV electron beam and Nd:YLF laser light (1047nm) is performed at 20 degrees interaction angle, so that about 300 eV soft X-ray is generated. In case of the pulse radiolysis experiments, the electron beam is used for the pump beam. The probe light is generated as white light by concentrating Nd:YLF laser light (1047nm) on the water cell. The measurement with about 30 ps (FWHM) time resolution of this system is demonstrated for the absorption of hydrated electrons. In this conference, we will present the experimental results, status of this system and future applications.  
 
THPLT102 Characteristics of Sealed-off Electron Gun with Wide Beam electron, radiation, cathode, vacuum 2727
 
  • V.M. Pirozhenko
    MRTI RAS, Moscow
  • A.N. Korolev, K.G. Simonov
    ISTOK, Moscow Region
  Compact sealed-off electron gun is a new promising type of devices. The gun generates wide beam of electrons with energy up to 200 keV and high peak power in 2-microsecond pulses. The beam is extracted to the atmosphere or a gas through the foil being uniformly distributed over the area of exposure. The gun contains the long ribbon cathode of oxide type, the electrodes for forming required distribution of the beam, the output window with 20-micron titanium foil, the high-voltage ceramic insulator, and the vacuum casing of rectangular shape. The gun is applied in the radiation technology system intended for the treatment of continuously moving tapes with 300 mm width. The gun design provides 10% uniformity of the radiation dose on the tape width.  
 
THPLT161 Compton X-ray Source electron, laser, diagnostics, quadrupole 2837
 
  • A.E. Vlieks, G. Caryotakis, D.W. Martin
    SLAC, Menlo Park, California
  • C.A. DeStefano, W.J. Frederick, J.P. Heritage, N.C. Luhmann Jr.
    UCD, Davis, California
  In an effort to develop a monochromatic, tunable source of X-rays in the 20-85 KeV energy range, a 5.5 cell X-band RF gun has been designed and tested. Together with a 1.05 m high gradient accelerating structure (an NLC Collider component), this system generates and accelerates a beam of electrons to energies greater than 60 MeV. Monochromatic X-rays are generated, via the Compton Effect, through a head-on collision of this beam with a multi-terawatt laser beam.We are currently measuring and analyzing the performance of the complete system, including the energy, monochromaticity and emittance of the electron beam, the laser system performance and the X-ray flux from the beam-laser interaction. A tunable, monochromatic X-ray source has important medical applications.We will report on the latest results as well as describe the experimental setup, components and diagnostics.  
 
THPLT181 A Tomographic Technique for Magnetized Beam Matching electron, linac, heavy-ion, quadrupole 2876
 
  • C. Montag, I. Ben-Zvi, J. Kewisch
    BNL, Upton, Long Island, New York
  To maintain low electron beam temperatures in the proposed RHIC electron cooler, careful matching of the magnetized beam from the source to the cooler solenoid is mandatory. We propose a tomographic technique to diagnose matching conditions. First simulation results will be presented.