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cathode

      
Paper Title Other Keywords Page
MOPKF005 Preliminary Results on a Low Emittance Gun Based on Field Emission electron, emittance, gun, 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.  
 
MOPKF014 Emittance Compensation of a Superconducting RF Photoelectron Gun by a Magnetic RF Field emittance, gun, 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 gun, 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

 
 
MOPKF017 New Simulations on Microbunching Instability at TTF2 simulation, linac, space-charge, damping 339
 
  • Y. Kim, Y. Kim, D. Son
    CHEP, Daegu
  • K. Floettmann
    DESY, Hamburg
  Microbunching instability in the FEL driver linac can be induced by collective self-fields such as longitudinal space charge, coherent synchrotron radiation, and geometric wakefields. In this paper, we describe the first start-to-end simulations including all important collective self-fields from the cathode to the end of TTF2 linac with 1.5 million macroparticles.  
 
MOPKF021 Properties of Cathodes Used in the Photoinjector RF Gun at the DESY VUV-FEL gun, 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.  
 
MOPKF026 Conditioning and High Power Test of the RF Guns at PITZ gun, 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.  
 
MOPKF027 Optimizing the PITZ Electron Source for the VUV-FEL emittance, laser, electron, simulation 360
 
  • M. Krasilnikov, J. Bähr, U. Gensch, H.-J. Grabosch, J.H. Han, D. Lipka, V. Miltchev, A. Oppelt, B. Petrosyan, D. Pose, L. Staykov, F. Stephan
    DESY Zeuthen, Zeuthen
  • K. Abrahamyan
    YerPhI, Yerevan
  • W. Ackermann, R. Cee, W.F.O. Müller, S. Setzer, T. Weiland
    TEMF, Darmstadt
  • G. Asova, G. Dimitrov, I. Tsakov
    INRNE, Sofia
  • I. Bohnet, J.-P. Carneiro, K. Floettmann, S. Riemann, S. Schreiber
    DESY, Hamburg
  • M.V. Hartrott, E. Jaeschke, D. Krämer, R. Richter
    BESSY GmbH, Berlin
  • P. Michelato, L. Monaco, C. Pagani, D. Sertore
    INFN/LASA, Segrate (MI)
  • J. Rossbach
    Uni HH, Hamburg
  • W. Sandner, I. Will
    MBI, Berlin
  The goal of the Photo Injector Test Facility at DESY Zeuthen (PITZ) is to test and optimize electron sources for Free Electron Lasers and future linear colliders. At the end of 2003 the first stage of PITZ (PITZ1) has been successfully completed, resulting in the installation of the PITZ RF gun at the Vacuum Ultra Violet - Free Electron Laser (VUV-FEL) at DESY Hamburg. The main results achieved during the PITZ1 extensive measurement program are discussed in this paper. A minimum normalized beam emittance of about 1.5 pi mm mrad for 1 nC electron bunch charge has been reached by optimizing numerous photo injector parameters, e.g. longitudinal and transverse profiles of the photocathode laser, RF phase, main and bucking solenoid current. The second stage of PITZ (PITZ2), being a large extension of the facility and its research program, has started now. Recent progress on the PITZ2 developments will be reported as well.  
 
MOPKF045 Cesium Telluride and Metals Photoelectron Thermal Emittance Measurements Using a Time-of-flight Spectrometer emittance, electron, laser, gun 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 gun, linac, emittance, 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.  
 
MOPKF054 Generation of Femtosecond Electron Pulses electron, simulation, radiation, linac 431
 
  • S. Rimjaem, V. Jinamoon, K. Kusoljariyakul, J. Saisut, C. Thongbai, T. Vilaithong
    FNRF, Chiang Mai
  • S. Chumphongphan
    Mae Fah Luang University, Chiang Rai
  • M.W. Rhodes, P. Wichaisirimongkol
    IST, Chiang Mai
  • H. Wiedemann
    SLAC/SSRL, Menlo Park, California
  Femtosecond electron pulses have become an interesting tool for basic and applied applications, especially in time-resolved experiments and dynamic studies of biomolecules. Intense, coherent radiation can be generated in a broad far-infrared spectrum with intensities, which are many orders of magnitude higher than conventional sources including synchrotron radiation sources. At the Fast Neutron Research Facility (FNRF), Chiangmai University (Thailand), the SURIYA project has been established with the aim to produce femtosecond pulses utilizing a combination of a S-band thermionic rf-gun and an alpha-magnet as the magnetic bunch compressor. A specially designed rf-gun has been constructed to obtain the optimum beam characteristics for best bunch compression. Simulation results show that the bunch lengths as short as 50 fs rms can be expected at the experimental station. This rf- gun, an alpha-magnet and a 20 MeV linac with beam transport system were installed and are being commissioned to generate femtosecond electron bunches. To measure the bunch length of the electron pulses, a Michelson interferometer will be used to observe the spectrum of coherent FIR transition radiation via optical autocorrelation. The main results of numerical simulations and experimental results will be discussed in this paper.  
 
MOPKF056 Injector Design for the 4GLS Energy Recovery Linac Prototype laser, booster, emittance, electron 437
 
  • C. Gerth, F.E. Hannon
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  Daresbury Laboratory has been given funding for the construction of an Energy Recovery Linac Prototype (ERLP) that operates at a target electron beam energy of 35 MeV and drives an IR oscillator FEL. The ERLP serves as a test-bed for the study of beam dynamics and accelerator technology important for the design and construction of the proposed 4th Generation Light Source (4GLS). A key component of the ERLP is a high-brightness injector. The injector consists of a DC photocathode gun, which is currently being built at Daresbury Laboratory and based on the design of the gun for the IR demonstrator FEL at Thomas Jefferson National Accelerator Facility. The gun section is followed by a conventional buncher cavity, a super-conducting booster and a transfer line to the main linac. In this paper, the design of the ERLP injector is discussed. The performance of the injector has been studied using the particle tracking code ASTRA.  
 
MOPKF070 Design of Injector Systems for LUX emittance, linac, gun, 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 gun, 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

 
 
MOPLT032 Breakdown Resistance of Refractory Metals Compared to Copper site, vacuum, collider, instrumentation 614
 
  • M. Taborelli, S. Calatroni, M. Kildemo
    CERN, Geneva
  The behaviour of Mo, W and Cu with respect to electrical breakdown in ultra high vacuum has been investigated by means of a capacitor discharge method. The maximum stable electric field and the field enhancement factor, beta, have been measured between electrodes of the same material in a sphere/plane geometry for anode and cathode, respectively. The maximum stable field increases as a function of the number of breakdown events for W and Mo. In contrast, no systematic increase is observed for Cu. The highest values obtained are typically 500 MV/m for W, 350 MV/m for Mo and only 180 MV/m for Cu. This conditioning, found for the refractory metals, corresponds to a simultaneous decrease of beta and is therefore related to the field emission properties of the surface and their modification upon sparking. Accordingly, high beta values and no applicable field increase occur for Cu even after repeated breakdown. The results are in agreement with rf breakdown experiments [*] performed on prototype 30 GHz accelerating structures for the CLIC accelerator.

* W. Wuensch, C. Achard, S. Döbert, H. H. Braun, I. Syratchev, M. Taborelli, I. Wilson, "A Demonstration of High Gradient Acceleration", CERN-AB-2003-048-RF; CLIC-Note-569, Proc. PAC2003.

 
 
MOPLT040 Test Results of Superconducting Cavities Produced and Prepared Completely in Industry vacuum, pick-up, superconductivity, linac 635
 
  • M. Pekeler, S. Bauer, B. Griep, H.P. Vogel, P. vom Stein
    ACCEL, Bergisch Gladbach
  Superconducting cavities for a variety of recent projects are produced and prepared for operation in industry. We report on test results of those cavities produced and prepared at ACCEL. The preparation of the cavities includes chemical treatment (BCP), rinsing with high pressure water and assembly in a clean room. The following cavity types were treated: 400 MHz single cell cavities for LHC, 500 MHz single cell cavities of the Cornell CESR design for our superconducting accelerating modules, 1300 MHz TESLA type cavities, 176 MHz and 160 MHz halfwave resonators and a 352 MHz CH-mode cavity for ion accelaration.  
 
MOPLT075 Ideal Waterbag Electron Bunches from an RF Photogun acceleration, electron, emittance, simulation 725
 
  • O.J. Luiten, M.J. Van der Wiel, S.B. van der Geer
    TUE, Eindhoven
  • F. Kiewiet
    FOM Rijnhuizen, Nieuwegein
  • M.J. de Loos
    PP, Soest
  With the implementation of fs mode-locked Ti:Sapphire lasers in high-gradient RF photoguns, a new charged particle acceleration regime has emerged, the so-called pancake regime. Pancake bunches have by definition a restframe length which is much smaller than the bunch radius. This geometry allows a relatively simple, but effective analytical description of the space-charge dominated, critical initial part of the acceleration trajectory. In high-gradient RF photoguns the pancake regime can be relevant up to several MeV. The general opinion is that extremely short bunches should be avoided during the initial stages of the acceleration process, because high space charge densities are always detrimental to the final beam quality. We show that this is not necessarily true: shorter bunches may even lead to better beams.  
 
MOPLT101 Performances of the Beam Generated by Metal-Dielectric Cathodes in RF Electron Guns gun, 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 gun, electron, ion, 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 gun, electron, 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.  
 
TUYLH01 Proton and Ion Sources for High Intensity Accelerators ion, plasma, extraction, emittance 103
 
  • R. Scrivens
    CERN, Geneva
  Future high intensity ion accelerators, including SNS, European Spallation Source, SPL etc, will require high current and high duty factor sources for protons, negative hydrogen and heavier ions. In order to achieve these goals, a comparison of the Electron Cyclotron Resonance, radio-frequency and Penning ion sources, among others, will be made. For each of these source types, the present operational sources will be compared to the state-of-the-art research devices with special attention given to reliability and availability. Finally, the future research and development aims will be discussed.  
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TUPKF024 Operation Experience with ALPI Nb/Cu Resonators acceleration, ion, superconductivity 1018
 
  • A.M. Porcellato, L. Bertazzo, M. De Lazzari, D. Giora, V. Palmieri, S. Stark, F. Stivanello
    INFN/LNL, Legnaro, Padova
  The refurbishing, by replacing the Pb superconducting film by Nb, of ALPI QW accelerating resonators was completed in 2003. All the 52 cavities are now in operation showing a large increase in the average accelerating field, which exceeds 4.5 MV/m (21 MV/m pick electrical surface field). The performance of renewed resonators has been increasing with time reaching 6MV/m in the last produced units. The increase in ALPI performance and the advantage in conditioning and setting time obtained by the upgrading process will be reported.  
 
TUPKF025 Superconducting Niobium Film for RF Applications vacuum, plasma, electron, laser 1021
 
  • A. Cianchi, L. Catani, A. Cianchi, S. Tazzari
    INFN-Roma II, Roma
  • Y.H. Akhmadeev
    Institute of High Current Electronics, Tomsk
  • A. Andreone, G. Cifariello, E. Di Gennaro, G. Lamura
    Naples University Federico II, Napoli
  • J.L. Langner
    The Andrzej Soltan Institute for Nuclear Studies, Centre Swierk, Swierk/Otwock
  • R.R. Russo
    Università di Roma II Tor Vergata, Roma
  Thin niobium film coated copper RF cavities are an interesting possible alternative to bulk-Nb cavities since copper is much cheaper than niobium, it has higher thermal conductivity and a better mechanical stability. Unfortunately, the observed degradation of the quality factor with increased cavity voltage of sputtered accelerating cavities restricts their usage in future large linear accelerators needing gradients higher than 15MV/m. We are developing an alternate deposition technology, based on a cathodic arc system working in UHV conditions. Its main advantages compared to standard sputtering are the ionized state of the evaporated material, the absence of gases to sustain the discharge, the much higher energy of atoms reaching the substrate surface and the possibility of higher deposition rates. To ignite the arc we use a Nd-YAG pulsed laser focused on the cathode surface that provides a reliable and ultraclean trigger. Recent results on the characterization of niobium film samples produced under different conditions are presented showing that the technique can produce bulk-like films suitable for RF superconducting applications.  
 
TUPKF034 Low Output-Impedance RF System for 2nd Harmonic Cavity in the ISIS Synchrotron feedback, impedance, synchrotron, beam-loading 1036
 
  • T. Oki, S. Fukumoto, Y. Irie, M. Muto, S. Takano, I. Yamane
    KEK, Ibaraki
  • R.G. Bendall, I.S.K. Gardner, M.G. Glover, J. Hirst, D. Jenkins, A. Morris, S. Stoneham, J.W.G. Thomason, T. Western
    CCLRC/RAL/ISIS, Chilton, Didcot, Oxon
  • J.C. Dooling, D. Horan, R. Kustom, M.E. Middendorf, G. Pile
    ANL, Argonne, Illinois
  In the ISIS facility based at Rutherford Appleton Laboratory (RAL) in the UK, second target station project was funded, which requires to increase the current intensity by 1.5-times (300 micro-A). Four 2nd harmonic RF cavities will be installed in the ISIS synchrotron in order to increase the trapping efficiency, and to mitigate the space charge detuning. A very low output-impedance RF system for the 2nd harmonic cavity has been developed by the collaboration between RAL, Argonne National Laboratory (US) and KEK (Japan). The system comprises the 240 kW triode as a final amplifier with plate-to-grid feedback path. The measured output-impedance was less than 30 ohms over the frequency range of 2.7 - 6.2 MHz, which agreed well with calculations. High power test was also performed under frequency swept mode at 50 Hz repetition. The operation was almost stable, and more than 12 kVpp was obtained as maximum. The voltage gain of the final amplifier was 25 - 30, which decreased gradually with frequency due to decreasing input-impedance of triode. The beam test is planned at ISIS in near future.  
 
TUPKF039 The Experiences of Operation and Performance about the 500 MHz CW Klystrons at the PLS Storage Ring klystron, storage-ring, electron, coupling 1051
 
  • J.S. Yang, M.-H. Chun, Y.J. Han, S.-H. Nam, I.H. Yu
    PAL, Pohang
  There are four RF stations to supply the energy to electron at the storage ring of the Pohang Light Source(PLS). From the beginning of the operation of RF system, 500MHz 60kW(CW) klystrons have been operated. As the operation time of the tubes are increased, their performances are decreased. Therefore three 60kW tubes were replaced with the same model and two 75kW klystrons were replaced with 60 kW klystrons so far. Nowadays two 75 kW and two 60 kW klystrons are operated in the RF system of PLS. Our experiences of the klystron operation and their general performance are described in this paper.  
 
TUPKF051 A 500 kV Power System for a Gridded Sheet-beam Klystron klystron, impedance, gun, 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 simulation, gun, 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.  
 
TUPKF065 Comparison of Klystron and Inductive Output Tubes (IOT) Vacuum-electron Devices for RF Amplifier Service in Free-electron Laser klystron, electron, laser, vacuum 1093
 
  • A. Zolfaghari, P. MacGibbon, W. North
    MIT/BLAC, Middleton, Massachusetts
  The MIT X-Ray Laser project, conceived to produce output in the 0.3 to 100 nanometer range, is based on a super-conducting 4-GEV linear accelerator, using 24 multi-cavity cryo-modules, each with its own dedicated RF amplifier, operating at 1.3 GHz. The continuous output of each amplifier is nominally 15 kW, with an optional repetitive pulse-modulation mode of 0.1 second pulse duration at one pulse per second. Although there are no fundamental restraints which preclude the consideration of any RF amplifier type, including solid-state or conventional triode or tetrode, the most appropriate current technology includes the Klystron and the IOT (Inductive Output Tube), also known by the CPI trade-name, Klystrode. The mechanisms by which the devices convert DC input power into RF output power are discussed. The devices are then compared with regard to availability (developmental or off-the-shelf), conversion efficiency, means of pulse-modulation, RF power gain, phase and amplitude stability (pushing factors), and acquisition and life-cycle costs.  
 
TUPKF066 34 Ghz, 45 MW Pulsed Magnicon: First Results gun, electron, plasma, 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.  
 
TUPKF076 Large Scale Production of 805-MHz Pulsed Klystrons for SNS klystron, gun, 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, gun 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.  
 
TUPKF080 Photoemission Properties of Lead laser, electron, heavy-ion, vacuum 1126
 
  • J. Smedley, T. Srinivasan-Rao, J. Warren
    BNL, Upton, Long Island, New York
  • R.S. Lefferts, A.R. Lipski
    SBUNSL, Stony Brook, New York
  • J. Sekutowicz
    Jefferson Lab, Newport News, Virginia
  There is significant interest in the possibility of building a super-conducting injector for high average current accelerator applications. One candidate for such a cavity design is superconducting lead. Such an injector would be made considerably simpler if it could be designed to use lead as the photocathode, eliminating the need for Cesiated materials in the injector. In this paper we present a study of the photoemission properties of lead at several UV wavelengths, including a study of the damage threshold of electroplated lead under laser cleaning. A quantum efficiency in excess of 0.1% has been achieved for a laser cleaned, electroplated lead sample with a laser wavelength of 193 nm.  
 
TUPLT060 Production of Radioactive Ion Beams for the EXCYT Facility target, ion, ion-source, cyclotron 1291
 
  • M. Menna, G. Cuttone, M. Re
    INFN/LNS, Catania
  The EXCYT facility (EXotics with CYclotron and Tandem) at the INFN-LNS is based on a K-800 Superconducting Cyclotron injecting stable heavy-ion beams (up to 80 MeV/amu, 1 emA) into a target-ion source assembly to produce the required nuclear species, and on a 15 MV Tandem for post-accelerating the radioactive beams. After thermal ANSYS simulations, during May 2003 the Target-Ion Source assembly (TIS) was successfully tested at GANIL under the same operational conditions that will be initially used at EXCYT. Yields and production efficiencies for 8,9Li were compatible with the ones obtained at SPIRAL. Following suggestions by the Referees and the LNS Research Division, we decided to deliver 8Li as the first EXCYT radioactive beam (primary beam 13C). This choice also takes in account the availability of MAGNEX in 2004 as well as the requests and the first results obtained by the Big Bang collaboration. The commissioning of the EXCYT facility is foreseen by the end of 2004 together with the start of nuclear experiments program. In this poster we also report prospective ion beams currently in development.  
 
TUPLT071 A 5 MeV Electron Linac for Radiation Processing electron, radiation, linac, focusing 1315
 
  • A. Trifirò, L. Auditore, R.C. Barnà, D. De Pasquale, A. Italiano, M. Trimarchi
    INFN - Gruppo Messina, S. Agata, Messina
  In recent years, radiation processing is rapidly growing in various field of industrial treatments and scientific research as a safe, reliable and economic technique. To match the requirements of several applications, a 5 MeV, 1 kW electron linac has been developed at the Dipartimento di Fisica (Università di Messina), in collaboration with the ENEA Accelerators Group (Frascati- Rome). This self- containing standing wave accelerator, driven by a 3 GHz, 2.5 MW Magnetron, has been designed, by means of the SUPERFISH and PARMELA codes, in such a way as to obtain an autofocusing structure, that will be used to develop a transportable system for 'in-situ' industrial radiography and X-ray digital tomography. For this accelerator, compact pulse forming circuits have been properly developed for the magnetron and the cathode, and pulse frequency can be varied ranging from 1 to 300 Hz, thus allowing the study of several applications of radiation processing. Main features of the accelerating structure, as well as beam spot dimensions, surface dose distribution and electron beam energy range will be described.  
 
TUPLT120 Commissioning of Electron Cooler EC-300 electron, gun, ion, 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.  
 
TUPLT133 Test Results of Injector Based on Resonance System with Evanescent Oscillations electron, resonance, bunching, emittance 1437
 
  • S.A. Perezhogin, M.I. Ayzatskiy, E.Z. Biller, K. Kramarenko, V.A. Kushnir, V.V. Mytrochenko, Z.V. Zhiglo
    NSC/KIPT, Kharkov
  Report presents results of tune-up and tests of the compact electron S ? band injector consisting of the low-voltage diode electron gun and the bunching system based on the resonant system with the evanescent oscillation. In the considered bunching system electrical field increased from beam entrance to an exit of the buncher. The injector designed for bunching of electron beam with initial energy of 25 keV and pulse current of 300 mA and accelerating it to the energy of 1 MeV.  
 
TUPLT139 Extending the Duty Cycle of the ISIS H Minus Ion Source, Thermal Considerations ion, ion-source, plasma, simulation 1452
 
  • D.C. Faircloth, J.W.G. Thomason
    CCLRC/RAL/ISIS, Chilton, Didcot, Oxon
  The ISIS H minus ion source is currently being developed on the Ion Source Development Rig (ISDR) at Rutherford Appleton Laboratory (RAL) in order to meet the requirements for the next generation of high power proton drivers. One key development goal is to increase the pulse width and duty cycle, but this has a significant effect on ion source temperatures if no other changes are made. A Finite Element Analysis (FEA) model has been produced to understand the steady state and dynamic thermal behavior of the source, and to investigate the design changes necessary to offset the extra heating.  
 
TUPLT164 CEBAF Injector Achieved World's Best Beam Quality for Three Simultaneous Beams with a Wide Range of Bunch Charges laser, space-charge, gun, electron 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.  
 
WEODCH02 Interaction of Stored Ions with Electron Target in Low Energy Electrostatic Ring electron, ion, target, proton 162
 
  • E. Syresin
    JINR, Dubna, Moscow Region
  • K. Noda
    NIRS, Chiba-shi
  • T. Tanabe
    KEK, Ibaraki
  The KEK electrostatic ring is used for investigations of molecular, bimolecular and DNA ions. The electron target installed in this ring has same construction as usual electron cooler. The interaction of stored ions with the electrons increases the ion lifetime at electron cooling caused by a suppression of the ion scattering on the residual gas atoms. The proton lifetime of 2 s was increased in the experiments by factor 2 at the electron cooling with the electron beam current of 0.2 mA, the proton energy of 20 keV and the residual gas pressure of 0.04 nTorr. However the electron-ion interaction can decrease the ion lifetime caused by an excitation of the transverse instability produced by an intensive electron beam. So in the KEK electrostatic ring the proton lifetime is reduced to 1.7 s at detuning of electron acceleration voltage from nominal cooler value on 0.4 V. The simulation of electron cooling and transverse instability of the light and DNA ions are discussed in this report.  
Video of talk
Transparencies
 
WEOALH01 Particle-in-cell Beam Dynamics Simulations simulation, electromagnetic-fields, damping, space-charge 170
 
  • T. Lau, E. Gjonaj, T. Weiland
    TEMF, Darmstadt
  We describe the application of the Conformal Finite Integration Technique (CFIT) in the time-domain to beam dynamics simulations with the Particle-In-Cell (PIC) method. The conformal method results in a more accurate field solution for complicated geometries than the traditional FIT approach. For long-time simulations we investigate several methods for the suppression of the spurious noise, typically emerging in PIC simulations. The results are compared with the analytical solution for a bunch in a semi-infinite waveguide for each of the presented methods. As a realistic example simulations for the RF-Gun installed at Photo Injector Test Facility in DESY Zeuthen (PITZ) will be presented.  
Video of talk
Transparencies
 
WEPKF069 52 kV Power Supply for Energy Recovery Linac Prototype RF klystron, power-supply, linac, vacuum 1762
 
  • J.E. Theed, M. Dykes, A. Gallagher, S.A. Griffiths, S.H. Hands, A.J. Moss, J.F. Orrett, C.J. White
    CCLRC/DL, Daresbury, Warrington, Cheshire
  Daresbury Laboratory is constructing a Radio-Frequency (RF) Test Facility to be capable of testing RF cavities for accelerator applications. Electrical power for the RF equipment will be provided from an existing -52 kV 6-pulse rectifier and transformer system capable of delivering 16A DC continuous current. A crowbar circuit will be provided to divert the large amount of stored energy in the smoothing capacitor bank in the event that a spark should occur between the cathode and the body or modulating anode. Traditionally, the crowbar has been provided by using an ignitron, but modern solid state devices have sufficient performance to meet the requirements. This paper discusses the numerous design options that were considered for the circuit parameters.  
 
WEPKF076 Solid-state Marx Bank Modulator for the Next Linear Collider klystron, pulsed-power, linear-collider, collider 1783
 
  • M.A. Kempkes, F.O. Arntz, J.A. Casey, M.P.J. Gaudreau
    Diversified Technologies, Inc., Bedford
  The Next Generation Linear Collider (NLC) will require hundreds to thousands of pulse modulators to service more than 3300 klystrons. DTI recently investigated the use of a solid-state Marx switch topology for the NLC, and has transitioned this work into the development of a full-scale, 500 V solid state Marx system. Combined with recent advances in semiconductor technology and packaging, these efforts have moved the performance of the Marx pulser far ahead of early estimates. The Marx pulser eliminates the pulse transformer, which is associated with significant loss of performance and a 15-20% penalty in the efficiency of a conventional modulator. The increase in efficiency attributable to the Marx topology can account for over $100M in power cost savings over ten years of NLC operation, an amount comparable to the acquisition costs of the pulsed power systems. In this paper, DTI will discuss the design and development of the Marx Bank modulator. Its performance scales to 125 ns risetime (10-90%) for either a 500 kV, 265 A pulse (for one klystron), or a 500 kV, 530 A pulse (for two klystrons). The use of a unique, common mode inductive charging system allows transfer of filament power without separate isolation transformers.  
 
WEPKF081 Prototype Development Progress toward a 500kV Solid State Marx Modulator klystron, linac, linear-collider, simulation 1792
 
  • G. Leyh
    SLAC, Menlo Park, California
  Recent advances in high voltage IGBT capabilities have made possible a range of novel solid-state modulator concepts that were unthinkable a decade ago. At present, there are two prototype solid-state modulator designs under evaluation at SLAC – A conventional pulse-transformer design using an 80kV solid-state switch in place of a thyratron, and an 'induction modulator', which uses a stack of magnetic cores to couple many paralleled primary windings to a common secondary winding. Both of these prototype modulators are currently driving actual klystron loads at SLAC. Another promising solid-state modulator concept still in the early stages of development is the Marx configuration – where an array of stacked modules generates high-voltage output pulses directly from a low DC input supply voltage. This scheme eliminates the large and costly magnetic cores inherent in the other two designs, resulting in a considerably simpler and cheaper mechanical solution. The main disadvantage to this approach is that the individual Marx sections must float at high voltages, complicating the distribution of power and timing signals. Several research groups have produced limited scale Marx prototypes in recent years. The largest prototype built to date [DTI] generates an output pulse of approximately 50kV, with plans to eventually move to higher voltage levels. This paper examines in closer detail the practical advantages and pitfalls of a solid-state Marx configuration, and explores a design approach with emphasis on performance, wall-plug efficiency, cost of manufacture, availability and ease of service. The paper presents electrical diagrams, mechanical CAD layout and preliminary prototype test data.  
 
WEPKF085 Secondary Electron Emission Measurements for TiN Coating on Stainless Steel of SNS Accumulator Ring Vacuum Chamber electron, vacuum, ion, simulation 1804
 
  • P. He, H.-C. Hseuh, R. Todd
    BNL, Upton, Long Island, New York
  • B. Henrist, N. Hilleret
    CERN, Geneva
  • S. Kato, M. Nishiwaki
    KEK, Ibaraki
  • R.E. Kirby, F. Le Pimpec, M.T.F. Pivi
    SLAC, Menlo Park, California
  BNL is responsible for the design and construction of the US Spallation Neutron Source (SNS) accumulator ring. Titanium Nitride(TiN) coating on the stainless steel vacuum chamber of the SNS accumulator ring is needed to reduce undesirable resonant multiplication of electrons. The Secondary Electron Yield(SEY) of TiN coated chamber material has been measured after coated samples were exposed to air and after electron and ion conditioning. We are reporting about the TiN coating system setup at BNL and SEY measurements results performed at CERN, SLAC and KEK. We also present updated electron-cloud simulation results for the SNS accumulator assuming different SEY values.  
 
WEPLT061 Influence of Beam Tube Obstacles on the Emittance of the PITZ Photoinjector emittance, laser, simulation, diagnostics 1984
 
  • S. Setzer, W. Ackermann, S. Schnepp, T. Weiland
    TEMF, Darmstadt
  For detailed analysis of space charge dominated beams inside an RF Photoinjector PIC-Codes like MAFIA TS2/3 can be used. While the interaction of particles with the sourrounding geometries are taken into account, the applicability of such codes is restricted due to simulation time and memory consumption as well as by numercial noise. Therefore only smaller sections of the whole injector can be calculated. On the other hand codes like ASTRA can be used to simulate the whole injector but no interaction between bunch and geometry is included. To make use of the individual advantages of each code discribed above an interface for bidirectional bunch exchange between the two programs has been implemented. This approach allows for applying the right simulation method depending on the physical effects under investigation. To demonstrate the importance of such an approach the results of detailed numerical studies of the impact of beam tube obstacles like the laser mirror on the achievable emittance of the PITZ RF Photoinjector further downstream will be presented.  
 
WEPLT100 Planar Electron Sources and the Electron Trap ELTRAP electron, plasma, laser, injection 2083
 
  • M. Cavenago
    INFN/LNL, Legnaro, Padova
  • G. Bettega, F. Cavaliere, A. Illiberi, R. Pozzoli, M. Romé, L. Serafini
    INFN-Milano, Milano
  Filamentation and other space charge effects (both transverse and longitudinal) of intense electron beams, found for example in rf photoinjectors (beam energy 1 MeV, current 100 A), are easily studied in small voltage traps and drift channels (0.01-10 kV), keeping the same perveance order. A suitable Malmberg-Penning trap, named ELTRAP, installed and operated at the University of Milan, is briefly described; trap length ranges from 10 cm to 1 m; an uniform magnetic field confines electron radially. Several experimental regimes were investigated with the internal CW planar electron source: plasma, beam-plasma, beam, depending on the injection/extraction method chosen. Evolution of electron vortices and virtual cathode formation is documented; analogy with meteorologic and astrophysical plasma is discussed. Upgrading with an external laser pulsed electron source is in course. Larger planar sources are also under construction. (Main classification 4: Beam Dynamics and Electro-magnetic Fields; D03 High Intensity, Incoherent Instabilities, Space Charge, Halos, Cooling; Other classification 8: Low and Intermediate Energy Accelerators and Sources; T12 Beam Injection/Extraction and Transport; T02 Lepton sources)  
 
WEPLT128 Charge Particle Source for Industrial and Research Accelerators Operating at the Poor Vacuum Conditions vacuum, electron, ion, background 2149
 
  • E.O. Popov, A.A. Pashkevich, S.O. Popov, A.V. Vitugov
    IOFFE, St. Petersburg
  We investigated the original method of fabrication of the great number of emitting tips by pulling liquid metal through the holes in track membrane under influence of electric field. The track membranes are produced by cyclotron of Physicotechnical Institute. This method enables to fabricate up to 1·108 emitting tips per square cm. Special test facility to investigate emitter parameters operating at different values of background residual gas pressure was designed and developed. The liquid metal multiple tip field emitters possess some unique characteristics which are attractive in accelerators for material irradiation: unlimited life expectancy, large current densities (about 100 mA per sq. cm), practically unlimited surface, stable emission in poor vacuum.  
 
WEPLT155 Effect of Dark Currents on the Accelerated Beam in an X-band Linac electron, simulation, positron, emittance 2203
 
  • V.A. Dolgashev
    SLAC/ARDA, Menlo Park, California
  • K.L.F. Bane, G.V. Stupakov, J. Wu
    SLAC, Menlo Park, California
  • T.O. Raubenheimer
    SLAC/NLC, Menlo Park, California
  X-band accelerating structures operate at surface gradients up to 120-180 MV/m. At these gradients, electron currents are emitted spontaneously from the structure walls ("dark currents") and generate additional electromagnetic fields inside the structure. We estimate the effect of these fields on the accelerated beam in a linac using two methods: a particle-in-cell simulation code MAGIC and a particle tracking code. We use the Fowler-Nordheim dependence of the emitted current on surface electric field with field enhancement factor beta. In simulations we consider geometries of traveling wave structures that have actually been built for the Next Linear Collider project.  
 
THPKF039 Study of Photo-cathode RF Gun for a High Brightness Electron Beam gun, 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.  
 
THPKF050 Electron Accelerator for Energy up to 5.0 MeV and Beam Power up to 50 KW with X-ray Converter electron, vacuum, extraction, coupling 2383
 
  • V. Auslender, A.A. Bryazgin, B.L. Faktorovich, E.N. Kokin, I. Makarov, S.A. Maximov, V.E. Nekhaev, A.D. Panfilov, V.M. Radchenko, M.A. Tiunov, V.O. Tkachenko, A.F.A. Tuvik, L.A. Voronin
    BINP SB RAS, Novosibirsk
  In recent time the new powerful industrial electron accelerators appear on market. It caused the increased interest to radiation technologies using high energy X-rays due to their high penetration ability. One of the promising directions is the creation of the irradiation installations for treatment of wide variety of food products. The report describes the industrial electron accelerator ILU-10 for electron energy up to 5 MeV and beam power up to 50 kW specially designed for use in industrial applications. The ILU-10 accelerator generates the vertical electron beam. The beam line turns the beam through an angle of 90 degrees and transports the beam to the vertically posed X-ray converter to generate the horizontal beam of X-rays. In the work presented results of measurements of the dose distribution profiles on the surface of treated products.  
 
THPKF058 Experimental Experience with a Thermionic RF-gun gun, 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, gun, 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.  
 
THPLT007 New Beam Profile Monitor Based on GEM Detector for the AD Transfer and Experimental Lines antiproton, hadron, electron, extraction 2472
 
  • J. Bosser, K. Gnanvo, J. Spanggaard, G. Tranquille
    CERN, Geneva
  Many multi-wire proportional chambers, (MWPC's), are installed on the CERN Antiproton Decelerator (AD) transfer and experimental lines. They are used for the steering and profile measurement of the low energy antiproton beam that is extracted at the energy of 5.3 MeV from the AD machine. At this very low energy, the standard MWPC's are not only destructive for the beam but also perturb strongly the 2D profile measurement. These chambers are also based on technology that is outdated and in recent years have shown to be fragile and expensive to repair. For these reasons a new, low cost profile monitor, based on a Gas Electron Multiplier (GEM) detector is under development as a possible replacement of the MWPC's. This new profile monitor will enable high precision, true 2D profile measurements of the low energy antiproton beam. In this paper, we present the modification of the standard GEM detector required by our specific application and the first results of the profile monitor with antiproton beams.  
 
THPLT018 Electron Beam Dynamics Simulations for the Low Emittance Gun emittance, gun, simulation, 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.  
 
THPLT035 Development of a 3D-Gun-Code based on a Charge Conserving Algorithm simulation, electron, space-charge, gun 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.  
 
THPLT050 End to End Simulations of the RX2 Beam Transport target, simulation, focusing, linac 2595
 
  • N. Pichoff, J.-M. Lagniel
    CEA/DAM, Bruyères-le-Châtel
  RX2 is a project aiming to produce a high flux of X-rays for radiography purpose. We proposed an RF linac using a DC photo-injector producing 20 bunches with 100nC each at 352 MHz. The beam is then injected in 4 RF superconducting cavities and accelerated to 40 MeV. It is then focused on a target producing X-rays. Here is presented the design, the specificities, and the beam simulations from the cathode to the target by coupling 2 multiparticle codes : PARMELA and PARTRAN.  
 
THPLT051 End to End Multiparticle Simulations of the AIRIX Linac target, simulation, electron, linac 2598
 
  • N. Pichoff, A. Compant La Fontaine
    CEA/DAM, Bruyères-le-Châtel
  AIRIX is a working 3 kA, 20 MeV induction accelerator. It has been designed with an enveloppe code : ENV. A new set of multiparticle codes (PBGUNS, MAGIC, PARMELA and PARTRAN) has been used recently to simulate the beam transport with an higher accuracy especially taking into account the field non-linearities. A dedicated space-charge routine has been written. The calculation results have been compared to experimental measurements.  
 
THPLT054 Emittance Diluition due to 3D Perturbations in RF Photoinjectors. emittance, focusing, space-charge, extraction 2607
 
  • M. Quattromini, L. Giannessi, C. Ronsivalle
    ENEA C.R. Frascati, Frascati (Roma)
  The predictions from different simulation codes are compared to investigate the effects of non axis-symmetric conditions, fluctuations in cathode's quantum efficiency and other sources of dishomogeneities in the performances of a typical RF photoinjector. The layout includes a RF gun and a focusing solenoid in a configuration aimed at minimizing the emittance growth due to space charge effects.  
 
THPLT059 Design Study of a Movable Emittance Meter Device for the SPARC Photoinjector emittance, simulation, space-charge, radiation 2622
 
  • A. Cianchi, L. Catani
    INFN-Roma II, Roma
  • M. Boscolo, M. Castellano, A. Clozza, G. Di Pirro, M. Ferrario, D. Filippetto, V. Fusco
    INFN/LNF, Frascati (Roma)
  • L. Giannessi, L. Picardi, M. Quattromini, C. Ronsivalle
    ENEA C.R. Frascati, Frascati (Roma)
  Preliminary studies of the SPARC rf gun are planned to obtain an accurate analysis and optimization of the emittance compensation scheme, measuring the beam emittance evolution downstream the RF gun with an appropriate diagnostic system. Since with a space charge dominated beam the use of the quad-scan method is not possible a 1D pepper-pot method will be used. A mask with narrow slits will be mounted on a movable support, spanning a 1.5 m meters region to measure the emittance in several positions and reconstruct its behavior in the post gun section. Numerical simulations of the measurement process, mainly based on PARMELA and TREDI, are used to estimate the achievable accuracy and to optimize the experimental setup. Wake field effects induced by the beam propagation through the long bellows have been also investigated with HOMDYN. Based on these simulations the design of the apparatus, called emittance-meter, has been realized and is under construction at LNF.  
 
THPLT061 Development of a Multibunch Photo-cathode RF Gun System gun, laser, 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.  
 
THPLT102 Characteristics of Sealed-off Electron Gun with Wide Beam electron, gun, radiation, 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.