Keyword: cathode
Paper Title Other Keywords Page
MOOAA01 Performance of the Cornell High-Brightness, High-Power Electron Injector gun, emittance, laser, electron 20
 
  • B.M. Dunham, A.C. Bartnik, I.V. Bazarov, L. Cultrera, J. Dobbins, C.M. Gulliford, G.H. Hoffstaetter, R.P.K. Kaplan, V.O. Kostroun, Y. Li, M. Liepe, X. Liu, F. Löhl, P. Quigley, D.H. Rice, E.N. Smith, K.W. Smolenski, M. Tigner, V. Veshcherevich, Z. Zhao
    CLASSE, Ithaca, New York, USA
  • S.S. Karkare, H. Li, J.M. Maxson
    Cornell University, Ithaca, New York, USA
  
  Funding: NSF DMR-0807731
The last year has seen significant progress in demonstrating the feasibility of a high current, high brightness photoinjector as required for the Energy Recovery Linac driven X-ray source at Cornell University. Both low emittances (0.4 mm-mrad rms normalized for 100% of the beam at 20 pC per bunch and 0.15 mm-mrad rms core emittance with 70% of the beam, and twice these values at 80 pC per bunch) and high average currents with a good lifetime well in excess of 1000 Coulombs at 5 MeV, 20 mA have been demonstrated. If these beams can be accelerated to 5 GeV without diluting the phase space, it would already provide a beam brightness higher than any existing storage ring. Operational experience, results, and the outlook for the future will be presented. 		 
slides icon Slides MOOAA01 [1.424 MB]  
 
MOPPC066 A Design of Thermionic Electron Gun for Traveling Wave Electron-linac in order to Inject Beam into Booster Synchrotron Accelerator gun, electron, simulation, synchrotron 286
 
  • S. Ahmadian, F. AbbasiDavani, F. Ghasemi, M.Sh. Shafiee
    sbu, Tehran, Iran
  
  Applying computational codes functioning on the basis of methods such as Finite Integration caused the designing of different parts of an accelerator to be done faster and with more precision. The first step in using new software is the validation of these codes by experimental results, analytic relations or validating them against other codes whose validity has already been proved. This research aims to design an appropriate structure for thermionic electron gun of traveling wave electron-linac to be used to inject beam into synchrotron accelerators. Firstly, a simple structure of an electron gun used in TWT tube was simulated, and the parameters such as current, perveance, waist beam position, waist beam radius, beam radius entering anode aperture, and also the electric potential variation in the anode-cathode distance and the electric field of anode aperture were compared by experimental results and analytic relations. After verifying the software accuracy, a design for an electron gun with energy and current respectively 200 keV, 18 A and also initial beam radius of 8mm and minimum beam radius of 2.4 mm situated at the distance of 67.44mm from the cathode, was presented.  
 
MOPPD046 Lifetime of the Highly Efficient H− Ion Sources ion, plasma, extraction, electron 466
 
  • V.G. Dudnikov
    Muons, Inc, Batavia, USA
  • D.S. Bollinger
    Fermilab, Batavia, USA
  • D.C. Faircloth, S.R. Lawrie
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  
  Funding: Work supported by grant DE-SC0006267, and STFC JAI grant ST/G008531
Factors limiting operating lifetime of Compact Surface Plasma Sources (CSPS) are analyzed and possible treatments for lifetime enhancement are considered. CSPSs have high plasma density (up to 1014 cm-3), high emission current density of negative ions (up to 8 A/cm2), small (1–5 mm) gap between cathode emitter, and a small extraction aperture in the anode. They are very simple, have high energy efficiency up to 100 mA/kW of discharge (~100 times higher then modern large Volume RF SPS) and have a high gas efficiency (up to 30%) using pulsed valves. CSPSs are very good for pulsed operation but electrode power density is often too high for dc operation. However, CSPSs were successfully adopted for DC operation with emission current density ~300 mA/cm2 in Hollow cathode Penning Discharge and up to 1 A/cm2 in Spherical focusing semiplanotron. Flakes from electrodes sputtering and blistering induced by back accelerated positive ions are the main reasons of ion source failure. Suppression of back accelerated positive ions, flakes explosion by pulsed discharges, and flakes gasification by discharge in NF3 (or XeF2) can be used for significant increase of operating lifetime of CSPSs. 		 
 
MOPPD048 Ribbon Electron Beam Profile Monitor for Bunched Beam Tomography electron, proton, ion, diagnostics 472
 
  • V.G. Dudnikov
    Muons, Inc, Batavia, USA
  • A.V. Aleksandrov
    ORNL, Oak Ridge, Tennessee, USA
  
  Funding: Work supported by Contract DE-AC05-00OR22725 and by STTR grant DE-SC0007559
Advanced beam diagnostics are essential for high performance accelerator beam production and for reliable accelerator operation. It is important to have noninvasive diagnostics which can be used continuously with intense beams of accelerated particles. Recently, an electron probe was successfully used to determine accelerated particle density distributions. However, the apparatus used for this diagnostic is large and complex which restricts its wider use for tomography of accelerated bunches. We propose to use a strip cathode is for ribbon electron beam formation instead of a scanning of pencil beam used in the previous electron probe bunch profile monitors. The apparatus with the strip cathode is smaller, has simpler design and less expensive manufacturing, can have better magnetic shielding, higher sensitivity, higher resolution, can have better measurement accuracy and better time resolution. With this device it is possible to develop almost ideal tomography diagnostics of bunches in linear accelerators and in circular accelerators and storage rings. 		 
 
MOPPP029 Photocathodes at FLASH electron, photon, gun, laser 625
 
  • S. Lederer, H. Hansen, H.-H. Sahling, S. Schreiber
    DESY, Hamburg, Germany
  • P. Michelato, L. Monaco, D. Sertore
    INFN/LASA, Segrate (MI), Italy
  
  For several years, cesium telluride photocathodes have been successfully used in the photoinjector of the Free-Electron-Laser FLASH at DESY, Germany. They show a high quantum efficiency and long lifetime and produce routinely thousands of bunches per second with a single bunch charge mostly in the range of 0.3 to 1 nC. Recent studies on lifetime, quantum efficiency, dark current, and operating experience is reported. At DESY, a new preparation system has been set-up. First cathodes have been produced and tested.  
 
MOPPP035 Initial Emittance and Temporal Response Measurement for GaAs Based Photocathodes electron, emittance, laser, cavity 640
 
  • S. Matsuba
    Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
  • Y. Honda, T. Miyajima, T. Uchiyama, M. Yamamoto
    KEK, Ibaraki, Japan
  • X.G. Jin
    Institute for Advanced Research, Nagoya, Japan
  • Y. Takeda
    Nagoya University, Nagoya, Japan
  
  For future light source based on Energy Recovery Linac (ERL) is planned in KEK. For the ERL, an ultra low emittance and fast temporal response and high current electron source is needed. To achieve these requirements, a high voltage DC gun with a Negative Electron Affinity photo-cathode is under development. In this development, it is important to investigate the performance of photo-cathodes. We have constructed an ERL gun test stand to measure emittance and temporal profile. We use a solenoid scan technique for emittance measurements and a deflecting cavity technique for temporal profile measurements. In this presentation, we introduce KEK ERL gun test stand and beam test results.  
 
MOPPP036 Progress in Reducing the Back-bombardment Effect in the ITC-RF gun for t-ACTS Project at Tohoku University electron, gun, dipole, simulation 643
 
  • X. Li, H. Hama, F. Hinode, S. Kashiwagi, M. Kawai, T. Muto, K. Nanbu, Y. Tanaka
    Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
  • F. Miyahara
    KEK, Ibaraki, Japan
  
  An ITC (independently tunable cells) thermionic RF gun* has been developed to produce sub-picosecond electron pulses as part of the injector for coherent terahertz radiation at Tohoku University. Both experiments and simulations have shown that the back-bombardment (B.B.) effect on the LaB6 cathode is a serious issue for option. A numerical model has been developed to evaluate the temperature increase of the cathode due to B.B. in which a 2D equation for heat conduction is solved by taking the back-streaming electrons into account. Using this model we have studied the possibility of suppressing the B.B. by employing dipole field and optimization of the cathode radius, compared with experimental data. Other methods and the prospect of the RF gun will also be reported.
* H. Hama et al., New J. Phys. 8 (2006) 292 		 
 
MOPPP039 Masked Photocathode for Photoinjectors electron, emittance, laser, vacuum 649
 
  • J. Qiang
    LBNL, Berkeley, California, USA
  
  Funding: This research was supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. This research used resources of the NERSC.
In this paper, we propose using masked photocathode in photoinjector for generating high brightness electron beam. An electrode with small hole is used as a mask to shield a large size photocathode from accelerating vacuum chamber. Using a mask will significantly increase lifetime of a photocathode by rotating unexplored photocathode material behind the electrode into the hole. Furthermore, the mask helps reduce dark current or secondary electron emission from the photocathode material. It also provides a control of initial beam transverse emittances. 		 
 
MOPPP041 Effect of Roughness on Emittance of Potassium Cesium Antimonide Photocathodes emittance, laser, electron, extraction 655
 
  • T. Vecchione, J. Feng, H.A. Padmore, W. Wan
    LBNL, Berkeley, California, USA
  • I. Ben-Zvi, M. Ruiz-Osés, L. Xue
    Stony Brook University, Stony Brook, USA
  • D. Dowell
    SLAC, Menlo Park, California, USA
  • T. Rao, J. Smedley
    BNL, Upton, Long Island, New York, USA
  
  Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences of the U. S. Department of Energy, under Contract DE-AC02-05CH11231, KC0407-ALSJNT-I0013, and DE-SC0005713
Here we present first measurements of the effect of roughness on the emittance of K2CsSb photocathodes under high fields. We show that for very thin cathodes the effect is negligible at up to 3 MV/m but for thicker and more efficient cathodes the effect becomes significant. We discuss ways to modify the deposition to circumvent this problem. 		 
 
MOPPP045 Status of the Wisconsin SRF Gun cavity, gun, laser, solenoid 661
 
  • R.A. Legg, J. Bisognano, M.J. Bissen, R.A. Bosch, D. Eisert, M.V. Fisher, M.A. Green, K. Jacobs, R.G. Keil, K.J. Kleman, J.G. Kulpin, G.C. Rogers, M.C. Severson
    UW-Madison/SRC, Madison, Wisconsin, USA
  • D. Yavuz
    UW-Madison/PD, Madison, Wisconsin, USA
  
  Funding: The University of Wisconsin SRF electron gun program is supported by DOE Award DE-SC0005264.
SRF electron guns hold out the promise of very bright beams for use in electron injectors, particularly for light source applications such as Free Electron Lasers. The University of Wisconsin is midway in a multi-year program to demonstrate a low frequency electron gun based on a quarter wave resonator cavity. The design includes active tuning and a high temperature superconducting solenoid for emittance compensation. We will report on the status of the 4 MeV SRF electron gun, including the cryomodule, the RF power coupler, the main RF power amplifier/low level RF control system, the photocathode laser system, and the diagnostic beamline. Installation is moving forward in a recently renovated experimental vault adjacent to the existing Aladdin synchrotron. First electron beam is expected in the summer 2012. 		 
 
MOPPP046 RF Gun Photocathode Research at SLAC gun, laser, emittance, electron 664
 
  • E.N. Jongewaard, R. Akre, A. Brachmann, W.J. Corbett, S. Gilevich, K. Grouev, P. Hering, P. Krejcik, J.R. Lewandowski, H. Loos, T. M. Montagne, J. Sheppard, P. Stefan, A.E. Vlieks, S.P. Weathersby, F. Zhou
    SLAC, Menlo Park, California, USA
  
  Funding: DOE contract DE-AC02-76SF00515.
LCLS is presently operating with a third copper photocathode in the original rf gun, with a quantum efficiency (QE) of ~1x10-4 and projected emittance eNx,y=0.45 μm at 250 pC bunch charge. The spare LCLS gun is installed in the SLAC Accelerator Structure Test Area (ASTA), processed to the design rf gradient of >120 MV/m. As part of a wider photocathode R&D program, a UV laser system and additional gun diagnostics are being installed at ASTA to measure QE, QE lifetime, and electron beam emittance under a variety of operating conditions. The near-term goals are to test and verify the spare photocathode production/installation sequence, including transfer from the final holding chamber to the rf gun. Mid- and longer-term goals include development of a rigorous understanding of plasma and laser-assisted surface conditioning and investigation of new, high-QE photocathode materials. In parallel, an x-ray photoemission spectroscopy station is nearing completion, to analyze Cu photocathode surface chemistry. In this paper we review the status and anticipated operating parameters of ASTA and the spectroscopy test chamber. 		 
 
MOPPP047 Characterization of the First SRF Electron Beam Source at the Naval Postgraduate School cavity, electron, SRF, coupling 667
 
  • A.D. Holmes, A.B. Baxter, C.W. Bennett, J.R. Harris, J.W. Lewellen, R. Swent
    NPS, Monterey, California, USA
  • J.M. Didoszak, J.M. Utschig
    ONR, Arlington, Virginia, USA
  
  In June 2011, the Naval Postgraduate school (NPS) received the 500 MHz Mark I quarter-wave superconducting RF (SRF) electron beam source and, among other firsts, completed the first cool down and characterization of an SRF beam source at a US Naval facility. The Mark I has a photocathode with adjustable position and uses a unique cascaded RF coupler design. As part of an on-going advanced electron source development project, the NPS Beam Physics Laboratory (BPL) team continues characterization of the Mark I cavity at various cathode stalk, coupler, and probe positions. Methods and experimentation used to measure the cavity Q and β, as well as characteristic results, with respect to coupler, cathode stalk, and probe positions are presented.  
 
MOPPP049 Deposition and In-Situ Characterization of Alkali Antimonide Photocathodes vacuum, synchrotron, scattering, diagnostics 670
 
  • X. Liang
    SBU, Stony Brook, New York, USA
  • K. Attenkofer
    ANL, Argonne, USA
  • I. Ben-Zvi, M. Ruiz-Osés
    Stony Brook University, Stony Brook, USA
  • H.A. Padmore, T. Vecchione
    LBNL, Berkeley, California, USA
  • S.G. Schubert
    HZB, Berlin, Germany
  • J. Smedley
    BNL, Upton, Long Island, New York, USA
  
  Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences of the U. S. Department of Energy, under Contract No. KC0407-ALSJNT-I0013, and DE-SC0005713.
Alkali antimonide cathodes have the potential to provide high quantum efficiency for visible light, and are significantly more tolerant of vacuum contaminants than GaAs, so they are attractive for high-average-current photoinjectors to generate high quality electron beams. These cathodes are crystalline; however, standard growth recipes used today do not produce large crystals. We have grown multi-alkali cathodes on silicon and molybdenum substrates with in-situ X-ray diffraction (XRD) and X-ray reflection (XRR) analysis. The correlation of the cathode structure to the growth parameters and quantum efficiency was explored. During the deposition and evaporation of Sb and K layers, the possibility of selective growth of specific crystalline orientation was observed via X-ray diffraction. 		 
 
MOPPR067 Simulations of Fast X-ray Detectors Based on Multichannel Plates electron, photon, simulation, scattering 939
 
  • Z. Insepov, B.W. Adams, J. Norem
    ANL, Argonne, USA
  • V. Ivanov
    Muons, Inc, Batavia, USA
  
  Funding: Argonne National Laboratory
High-performance detectors with high spatial and time resolutions are required for imaging of fast processes, time-resolved coherent scattering, and time-resolved x-ray spectroscopy. Recent developments in micro-channel plate (MCP) technology are important for sub-ns and 2d-spatially resolving x-ray detection. A Monte Carlo code was used to calculate the yields of secondary electrons emitted from a photo-cathode irradiated by X-rays, E=1-10 keV. Several photo-cathode materials were tested, including Al2O3, MgO, carbon, copper, WO3. The calculated emissive characteristics were used as input parameters of a second Monte Carlo code that was capable of calculating the gain/time characteristics of the MCP based X-Ray detector. A new type of X-Ray detector based on MCPs coated by resistive and emissive layers inside the pores by using atomic-layer deposition (ALD) promises a large parameter space where optimizations can take place. These optimizations for x-ray-specific applications are expected to improve the spatial resolution to 100 microns and the time resolution to 50 ps, and the development of high-quantum-yield photo-cathodes based on MCPs with grazing incidence inside the pores. 		 
 
MOPPR075 Status of the APEX Beam Diagnostic and First Measurements laser, diagnostics, electron, gun 963
 
  • D. Filippetto, M.J. Chin, C.W. Cork, S. De Santis, L.R. Doolittle, W.E. Norum, C. F. Papadopoulos, G.J. Portmann, D.G. Quintas, F. Sannibale, R.P. Wells, M.S. Zolotorev
    LBNL, Berkeley, California, USA
  
  The APEX project aims to the construction of a high brightness high repetition rate photo-injector at LBNL. In its first phase a 750 keV electron bunch is produced at a maximum repetition rate of 1 MHz, with an adjustable charge per bunch spanning the pC-to-nC region. A load lock system is foreseen to test different cathodes without the need of breaking the vacuum and the downstream diagnostic is used to characterize the photo-emitted beam brightness. In the initial phase the main effort is directed toward the measurement of photocurrent, dark current, thermal emittance and electron beam kinetic energy. In a successive phase, diagnostic for full 6D phase space characterization of space charge dominated beams will be added to the beamline. We report and discuss the present diagnostic beamline layout, first beam measurements and future upgrades.  
 
TUPPC024 R&D of an Ultrafast Probe Apparatus Based on MeV Electron Diffraction at Tsinghua University electron, solenoid, simulation, emittance 1215
 
  • X.H. Lu, Y.-C. Du, W.-H. Huang, H.J. Qian, C.-X. Tang
    TUB, Beijing, People's Republic of China
  
  Funding: This work is supported by National Natural Science Foundation of China and National Basic Research Program of China (973 Program).
An ultrafast probe apparatus based on MeV ultrafast electron diffraction is developed at Tsinghua University. It aims at generating 1.5 to 3 MeV pulse with sub-pC charge and sub-ps pulse length for pump-probe experiments. It consists of an S-band 1.6-cell radiofrequency photocathode gun, a solenoid, a sample chamber, a deflecting cavity, a detection system and other diagnostics tools. Simulations show the position of solenoid coil affects the spot size on detection screen and the charge of collimated bunch significantly. The collimator is found to be helpful to stabilize the charge of collimated bunch and reduce its normalized emittance. The construction of the apparatus is almost finished and the commissioning test will start soon. 		 
 
TUPPD034 Multi-bunch Beam Generation by Photo-cathode RF Gun for KEK-STF cavity, laser, gun, electron 1479
 
  • M. Kuriki, S. Hosoda, H. Iijima
    HU/AdSM, Higashi-Hiroshima, Japan
  • A. Ayaka
    Sokendai, Ibaraki, Japan
  • H. Hayano, J. Urakawa, K. Watanabe
    KEK, Ibaraki, Japan
  • G. Isoyama, R. Kato, K. Kawase
    ISIR, Osaka, Japan
  • S. Kashiwagi
    Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
  • K. Sakaue
    RISE, Tokyo, Japan
  
  Funding: MEXT, Quantum beam project.
KEK-STF is doing R&D of Super-Conducting (SC) accelerator technology for ILC (International Linear Collider), based on 1.3 GHz RF system. For STF and ILC, the pulse length is 1ms and the repetition is 5Hz. We developed a L-band Normal-Conducting RF gun designed by DESY to provide electron beam over such long pulse duration. For NC Photo-cathode RF gun, such high duty and long pulse operation is a challenging task, because the detuning by the heat load of cavity dissipation power is significant. The RF gun provides the electron pulse train to SC accelerator modules which will be operated at 31.5 MV/m gradient. Precise RF control is essential for SC accelerator because the beam loading and input RF power should be well ballanced for a stable operation. The beam test to demonstrate the stable opeation is very important for SC accelerator R&D. The system is also used to demonstrate high-flux quasi-monochromatic X-ray generation by inverse Compton scattering at KEK-STF. The experiment is carried out from April 2012 to November 2012 at KEK-STF. We report the latest status of the multi-bunch generation by the RF gun. 		 
 
TUPPD035 SuperKEKB Injector Upgrade for High Charge and Low Emittance Electron Beam emittance, gun, alignment, wakefield 1482
 
  • M. Yoshida, N. Iida, Y. Ogawa, M. Sato, L. Zang
    KEK, Ibaraki, Japan
  
  The design strategy of SuperKEKB is based on the nano-beam scheme. The dynamic aperture decreases due to the very small beta function at the interaction point. Thus the injector upgrade is required to obtain the low emittance and high charge beam corresponding to the short beam life and small injection acceptance. The required beam parameters are 5 nC, 20 mm mrad and 4 nC, 6 mm mrad for the electron and positron respectively. For the electron beam, new photocathode RF-Gun with the focusing electric field was installed. Further the emittance growth in the linac is an important issue for the low emittance injection. We will report the machine study of the RF-Gun and the emittance growth through the linac.  
 
TUPPD050 Investigation of Laser-cleaning Process on Lead Photocathodes laser, electron, photon, high-voltage 1515
 
  • S.G. Schubert, R. Barday, T. Kamps, T. Quast, A. Varykhalov
    HZB, Berlin, Germany
  • R. Nietubyć
    The Andrzej Soltan Institute for Nuclear Studies, Centre Świerk, Świerk/Otwock, Poland
  • F. Siewert
    BESSY GmbH, Berlin, Germany
  • J. Smedley
    BNL, Upton, Long Island, New York, USA
  • G. Weinberg
    FHI, Berlin, Germany
  
  Funding: Work supported by Bundesministerium für Bildung und Forschung and Land Berlin.
Metal photocathodes are widely used in electron injectors due to their stability and long life time; unfortunately they exhibit low quantum efficiency. Due to adsorption of contaminants the work function increases and thus the quantum efficiency is further reduced. In order to increase the quantum efficiency of our Pb cathode we performed a cleaning procedure by means of a high power excimer laser as suggested by Smedley*. The process was studied on witness samples in a combined photo emission, SEM and quantum efficiency measurement study. Thin Lead films were arc-deposited on optical polished Mo-substrates**. Before and after irradiation the sample was analyzed at 140 eV photon energy at a XPS/ARPES end station at the synchrotron radiation source Bessy II. We followed the change of the Pb 5d signals. In the initial situation we observed signals originating from metallic Pb and Pb in the oxidized state, respectively. Since the surface roughness is of concern for the injector performance it was examined before and after the irradiation procedure with white-light-interferometry and the surface morphology by means of SEM.
*J. Smedley et al, PRST-AB 11, 013502 (2008).
** Rao, T. et al., IPAC 2010, THPEC020 (2010).
 		 
 
TUPPD051 Operational Experience with the Nb/Pb SRF Photoelectron Gun emittance, solenoid, laser, cavity 1518
 
  • T. Kamps, W. Anders, R. Barday, A. Jankowiak, J. Knobloch, O. Kugeler, A.N. Matveenko, A. Neumann, T. Quast, J. Rudolph, S.G. Schubert, J. Völker
    HZB, Berlin, Germany
  • P. Kneisel
    JLAB, Newport News, Virginia, USA
  • R. Nietubyć
    The Andrzej Soltan Institute for Nuclear Studies, Centre Świerk, Świerk/Otwock, Poland
  • J.K. Sekutowicz
    DESY, Hamburg, Germany
  • J. Smedley
    BNL, Upton, Long Island, New York, USA
  • J. Teichert
    HZDR, Dresden, Germany
  • V. Volkov
    BINP SB RAS, Novosibirsk, Russia
  • I. Will
    MBI, Berlin, Germany
  
  SRF photoelectron guns offer the promise of high brightness, high average current beam production for the next generation of accelerator driven light sources such as free electron lasers, THz radiation sources or energy-recovery linac driven synchrotron radiation sources. In a first step a fully superconducting RF (SRF) photoelectron gun is under development by a collaboration between HZB, DESY, JLAB, BNL and NCBJ. The aim of the experiment is to understand and improve the performance of a Nb SRF gun cavity coated with a small metallic Pb cathode film on the cavity backplane. This paper describes the highlights from the commissioning and beam parameter measurements. The main focus is on lessons learned from operation of the SRF gun.  
 
TUPPD054 Research Activities on Photocathodes for HZDR SRF Gun gun, SRF, vacuum, electron 1524
 
  • R. Xiang
    FZD, Dresden, Germany
  • A. Arnold, M. Freitag, P. Michel, P. Murcek, J. Teichert
    HZDR, Dresden, Germany
  
  Funding: We acknowledge the support of the European Community-Research Infrastructure Activity (EuCARD, contract number 227579), as well German Federal Ministry of Education and Research grant 05 ES4BR1/8.
Since 2005 the photocathode laboratory has been in operation at HZDR. The main goal is to prepare Cs2Te photocathodes for the SRF gun. A vacuum transport system with UHV is used to move the cathodes from preparation lab to accelerator hall. Up to now 31 Cs2Te photocathodes have been deposited and eight of them have been used in the SRF gun. Quantum efficiency of 1% and lifetime of months can be maintained during the gun operation. At the same time activities are directed towards new photocathode materials with high Q.E. for high current electron sources. Cs3Sb and GaN(Cs) photocathodes have been tested as new candidates, and the design of a preparation system for GaAs(Cs, O) is ongoing. 		 
 
TUPPD056 Development of a Photo-injector Laser System for KEK ERL Test Accelerator laser, cavity, controls, alignment 1530
 
  • Y. Honda
    KEK, Ibaraki, Japan
  
  As a test accelerator for future light source, Compact Energy Recovery Linac has been constructed in KEK. For its photo-injector, we have been developing a laser system. It requires high repetition rate and high average power at a visible wavelength. Development of an high power fiber amplifier and high efficiency wavelength conversion system utilizing an optical cavity will be reported.  
 
TUPPD057 High Charge Low Emittance RF Gun for SuperKEKB gun, emittance, injection, laser 1533
 
  • T. Natsui, Y. Ogawa, M. Yoshida, X. Zhou
    KEK, Ibaraki, Japan
  
  We are developing a new RF gun for SuperKEKB. We are upgrading KEKB to SuperKEKB now. High charge low emittance electron and positron beams are required for SuperKEKB. We will generate 7.0 GeV electron beam at 5 nC 20 mm-mrad by J-linac. In this linac, a photo cathode S-band RF gun will be used as the electron beam source. For this reason, we are developing an advanced RF gun. Now, we are testing a Disk and Washer (DAW) type RF gun. Its photo cathode material is LaB6. Normally, LaB6 is used as a thermionic cathode, but it is suitable for　long-life photo cathode operation. This gun has a strong focusing field at the cathode and the acceleration field distribution also has a focusing effect. We will obtain 3.2 MeV beam energy with the gun. The design of RF gun and experimental results will be shown.  
 
TUPPD058 Development of an RF Electron Gun for Ultra-Short Bunch Generation gun, electron, cavity, simulation 1536
 
  • Y. Koshiba, T. Aoki, K. Sakaue, M. Washio
    RISE, Tokyo, Japan
  • T. Takatomi, J. Urakawa
    KEK, Ibaraki, Japan
  
  At Waseda University, various researches are done using a photocathode rf electron gun with a 1.6 cell cavity. Now we are developing a new rf cavity specialized for producing an ultra-short electron bunch, with the collaboration of High Energy Accelerator Research Organization (KEK). We have used SUPERFISH for designing the new rf cavity and PARMELA for beam tracking. The new rf cavity has an extra cell following the 1.6 cell. The extra cell can chirp the energy of electron bunch so we call it ECC (Energy Chirping Cell). ECC chirp the energy because we shortened the length of iris just before the ECC and also the length of ECC itself. Moreover, electric field in ECC is made to be stronger than others. We have confirmed on PARMELA that ECC rf gun can generate an 100pC electron bunch less than 200fsec with the energy of 4.5MeV at about 2.5m away from the cathode. Such an ultra-short electron bunch enables us to generate a coherent terahertz light using ultra-short electron bunch by synchrotron radiation or transition radiation. In this conference, we would like to introduce the detail of the design of this new ECC rf gun, the present progresses and future prospects.  
 
TUPPD062 The Source of Emittance Dilution and photoemission tunneling effect in Photocathode RF Guns emittance, laser, cavity, simulation 1542
 
  • V. Volkov
    BINP SB RAS, Novosibirsk, Russia
  • R. Barday, T. Kamps, J. Knobloch, A.N. Matveenko, S.G. Schubert, J. Völker
    HZB, Berlin, Germany
  • J.K. Sekutowicz
    DESY, Hamburg, Germany
  
  Funding: Work supported by Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Association VH-NG-636 and HRJRG-214.
Experimental data on HoBiCaT SRF photoinjector give an emittance which is much larger than the predicted thermal emittance. Modeling of photocathode RF gun beams with the different imperfections of experimental setup (alignment errors, inhomogeneity of quantum efficiency and laser power distributions on the cathode) is given. The main reason for the beam emittance dilution is photocathode field imperfections induced by field emitters that change the local electric field. Some field models of such photocathodes are tested in the simulations. The dependence of photocathode beam currents on the surface electric field was measured with the HoBiCaT SRF Photoinjector. The dependence can be explained by the tunneling effect described by Fowler-Nordheim like equation and is difficult to explain by usually applying Schottky effect. 		 
 
TUPPD064 Cathode Insert Design for SC RF Guns gun, cavity, multipactoring, HOM 1548
 
  • V. Volkov
    BINP SB RAS, Novosibirsk, Russia
  • R. Barday, T. Kamps, J. Knobloch, A.N. Matveenko
    HZB, Berlin, Germany
  
  Funding: Work supported by Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Assiciation VH-NG-636 and HRJRG-214.
The cathode inserts in superconducting (SC) RF guns are normal conducting devices attached to a SC RF gun cavity. They enable the photocathode replacement and, at the same time, preserve high quality factor and high fields in the RF guns. However, the insert may also limit the gun performance because of multipacting etc. The experience gathered in early designs at Wuppertal [1], and, more recently at BNL [2] and HZDR [3] is taken into account. We consider the design structure of the cathode insert worked out by BINP for 1 cell prototype of SC HZDR RF gun [4]. The detailed electric, mechanic, and thermal calculations of the initial [4] and the upgraded design are presented in this paper.
* A. Michalke et al., EPAC'92, p. 1014 (1992).
** A. Burrill et al., PAC07, p. 2544 (2007).
*** D. Janssen et al., NIM A507, 314 (2003).
**** D. Janssen et al., NIM A445, 408 (2000). 		 
 
TUPPD065 An Electron Gun Test Stand to Prepare for the MAX IV Project gun, injection, coupling, linac 1551
 
  • S. Werin, E. Elafifi, M. Eriksson, D. Kumbaro, F. Lindau, S. Thorin
    MAX-lab, Lund, Sweden
  • E. Mansten
    Lund University, Division of Atomic Physics, Lund, Sweden
  
  The MAX IV facility, currently under construction, will include a 3 GeV linac injector with two RF guns providing beams for the two operations modes: ring injection and the Short Pulse Facility. The ring injection will be done by a thermionic 3 GHz RF gun developing from the current MAX-lab RF gun. The SPF gun will be a laser driven photo cathode 3 GHz RF gun based on the 1.6 cell BNL/SLAC type. The guns will be operated with short (0.7 us) RF pulses from a SLED system. A test stand to fine tune the operation of the two different systems has been assembled at the MAX IV laboratory (former MAX-lab). The experience in RF commissioning and initial measurements of energy, charge and quantum efficiency will be reported and the extension of the test stand for full emittance characterization will be outlined.  
 
TUPPD066 Lifetime Studies of Cs2Te Cathodes at the PHIN RF Photoinjector at CERN vacuum, gun, laser, beam-losses 1554
 
  • C. Heßler, E. Chevallay, M. Divall Csatari, S. Döbert, V. Fedosseev
    CERN, Geneva, Switzerland
  
  The PHIN photoinjector has been developed to study the feasibility of a photoinjector option for the CLIC (Compact LInear Collider) drive beam as an alternative to the baseline design, using a thermionic gun. The CLIC drive beam requires a high charge of 8.4 nC per bunch in 0.14 ms long trains, with 500 MHz bunch spacing and 50 Hz macro pulse repetition rate, which corresponds to a total charge per macro pulse of 0.59 mC. This means unusually high peak and average currents for photoinjectors and is challenging with respect to the cathode lifetime. In this paper detailed studies of the lifetime of Cs2Te cathodes, produced by the co-evaporation technique, with respect to bunch charge, train length and vacuum level are presented. Furthermore, the impact of the train length and bunch charge on the vacuum level will be discussed and steps to extend the lifetime will be outlined.  
 
TUPPD067 Experimental Facility for Measuring the Electron Energy Distribution from Photocathodes electron, vacuum, brightness, laser 1557
 
  • L.B. Jones, R.J. Cash, B.D. Fell, J.W. McKenzie, K.J. Middleman, B.L. Militsyn
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • H.E. Scheibler, A.S. Terekhov
    ISP, Novosibirsk, Russia
  
  ASTeC have spent several years developing a GaAs Photocathode Preparation Facility (PPF) which routinely produces cathodes with quantum efficiencies (Q.E.) up to 20% at 635 nm*. The goal is to use these cathodes in high-average-current high-brightness injectors for particle accelerators. Electron injector brightness is driven by photocathode emittance, and brightness will be increased significantly by reducing the longitudinal and transverse energy spread. We are constructing an experimental system for measurement of the horizontal and transverse energy spreads at room and LN2-temperature which accepts photocathodes from the PPF. The sample will be illuminated by a small, variable-wavelength light spot. The beam image will be projected onto a detector comprised of 3 grids which act as an energy filter, a micro-channel plate and a phosphor screen. A low-noise CCD camera will capture screen images, and the electron distribution and energy spread will be extracted through analysis of these images as a function of the grid potentials. The system will include a leak valve to progressively degrade the cathode, and thus allow its properties to be measured as a function of Q.E.
* Proc IPAC ’11, THPC129 (2011). 		 
 
TUPPD069 Schottky-Enabled Photoemission and Dark Current Measurements - Toward an Alternate Approach to Fowler-Nordheim Plot Analysis gun, laser, site, photon 1563
 
  • E.E. Wisniewski, W. Gai, J.G. Power
    ANL, Argonne, USA
  • H. Chen, Y.-C. Du, Hua, J.F. Hua, W.-H. Huang, C.-X. Tang, L.X. Yan, Y. You
    TUB, Beijing, People's Republic of China
  • A. Grudiev, W. Wuensch
    CERN, Geneva, Switzerland
  • E.E. Wisniewski
    Illinois Institute of Technology, Chicago, Illinois, USA
  
  Field-emitted dark current, a major gradient-limiting factor in RF cavities, is usually analyzed via Fowler-Nordheim (FN) plots. Traditionally, field emission is attributed to geometrical perturbations on the bulk surface whose field enhancement factor (beta) and the emitting area (A) can be extracted from the FN plot. Field enhancement factors extracted in this way are typically much too high (1 to 2 orders of magnitude) to be explainable by either the geometric projection model applied to the measured surface roughness or by field enhancement factors extracted from Schottky-enabled photoemission measurements. We compare traditional analysis of FN plots to an alternate approach employing local work function variation. This is illustrated by comparative analysis of recent dark current and Schottky-enabled photoemission data taken at Tsinghua S-band RF gun. We conclude by describing a possible experimental plan for discrimination of variation of local work function vs. local field enhancement.  
 
TUPPD070 Kelvin Probe Studies of a Cesium Telluride Photocathode for the AWA Photoinjector electron, vacuum, photon, wakefield 1566
 
  • E.E. Wisniewski, K.C. Harkay, Z.M. Yusof
    ANL, Argonne, USA
  • L.K. Spentzouris, J. Terry, D.G. Velazquez, E.E. Wisniewski
    Illinois Institute of Technology, Chicago, Illinois, USA
  
  Cesium telluride is an important photocathode as an electron source for particle accelerators. It has a relatively high quantum efficiency (>1%), is sufficiently robust in a photoinjector, and has a long lifetime. This photocathode is grown in-house for the new Argonne Wakefield Accelerator (AWA) to produce high charge per bunch (~50 nC). Here, we present a study of the "work function" of a cesium telluride photocathode using the Kelvin Probe technique. The study includes an investigation of the correlation between the quantum efficiency and the work function, the effect of photocathode aging, the surprising effect of UV exposure on the work function, and the puzzling behavior of the work function during and after photocathode rejuvenation via heating.  
 
TUPPD071 Development of Cesium Telluride Photocathodes for the AWA Accelerator Upgrade wakefield, vacuum, electron, acceleration 1569
 
  • Z.M. Yusof, M.E. Conde, W. Gai
    ANL, Argonne, USA
  • L.K. Spentzouris, E.E. Wisniewski
    Illinois Institute of Technology, Chicago, Illinois, USA
  
  Funding: U.S. Department of Energy Office of Science under Contract No. DE-AC02-06CH11357.
Cesium telluride photocathodes have been fabricated for the Argonne Wakefield Accelerator (AWA) upgrade. The as-deposited photocathodes have consistently produced quantum efficiency values better than 10% with 254 nm light source and with variation of less than 5% over a circular area of 1.2 inches in diameter. We present various characterizations of the photocathode that have performed, including rejuvenation, lifetime, and performance in the L-band AWA photoinjector. 		 
 
TUPPD076 Photocathode Studies for the SPEAR3 Injector RF Gun linac, gun, laser, klystron 1575
 
  • S. Park, W.J. Corbett, S.M. Gierman, J.R. Maldonado
    SLAC, Menlo Park, California, USA
  
  Funding: Work supported by U.S. Department of Energy Contract DE-AC03- 76SF00515 and Office of Basic Energy Sciences, Division of Chemical Sciences.
The electron gun for the SPEAR3 injector operates with a warm thermionic dispenser cathode immersed in a 1.5-cell RF structure. At each injection cycle the gun accelerates several thousand electron bunches up to ~3 MeV during a 2.5us rf pulse. The individual bunches are then compressed by an alpha magnet and a traveling-wave chopper selects 3-5 bunches so they don’t cause beam loading to the linac, where the accelerated bunches reach 120 MeV for subsequent capture in a single booster synchrotron bucket. Tests are underway to operate the dispenser cathode as a cold electron photo-emitter driven by an external laser system. Eventually, without the copper, this will enable multi-bunch injections to the Booster and SPEAR3. In parallel, tests are underway to evaluate quantum efficiency and beam emittance for a beam emitted from a CsBr photocathode with ns- and ps-pulses of UV laser light. In this paper we report on both the cold cathode electron gun operation studies for SPEAR3 and the CsBr research aimed at developing advanced cathode materials for future applications. 		 
 
TUPPD078 A Novel Design of a High Brightness Superconducting RF Photoinjector Gun Cavity gun, cavity, SRF, emittance 1581
 
  • F. Marhauser, R. Rodriguez
    MuPlus, Inc., Newport News, USA
  • Z. Li
    SLAC, Menlo Park, California, USA
  
  Funding: Work supported under U.S. DOE Grant Application Number 98802B12-I
Next generation electron accelerators for research, medical, defense or industrial use are in need of electron sources operating at high repetition rates of 1 MHz and beyond, with normalized emittance of 1 mm-mrad or less and bunch charges as much as one nC or more. A conceptual layout of a novel superconducting RF photoinjector gun cavity (SRF gun) is proposed, which can provide unprecedented flexibility to vary beam pulse patterns in the MHz regime and beyond at average currents around 1 mA. It does not require an opening in the center of the back wall and avoids the complex cathode exchange system, but still allows an exchange or refurbishment of the cathode. The demountable back plate has the major benefit to clean the cavity cells independently from the back wall carrying a superconductive photocathode. This mitigates risks of cavity contamination and eases fabrication and chemical post-processing to achieve high accelerating fields, a key parameter to guarantee high brightness beams. 		 
 
TUPPD080 Design of Ultrafast High-Brightness Electron Source electron, gun, brightness, laser 1587
 
  • J.H. Park, H. Bluem, J. Rathke, T. Schultheiss, A.M.M. Todd
    AES, Princeton, New Jersey, USA
  
  Funding: This work was supported by the U.S. Department of Energy, under Contract No. DE-SC0006210.
Generation and preservation of ultrafast electron beams is one of the major challenges in accelerator R&D. Space charge forces play a fundamental role in emittance dilution and bunch lengthening for all high brightness beams. In order to generate and preserve the ultrafast high-brightness electron beam, transverse and longitudinal space charge effects have to be considered. Several approaches to achieving ultra-short bunches have been explored such as velocity bunching and magnetic compression. However, each option suffers drawbacks in achieving a compact ultrafast high-brightness source. We present an alternative scheme to achieve an ultrafast high-brightness electron beam using a radial bunch compression technique in an x-band photocathode RF electron gun. By compensating the path length difference with a curved cathode and using an extremely high acceleration gradient (greater than 200 MV/m), we seek to deliver 100 pC, 100 fsec bunches. 		 
 
TUPPD081 Development of Carbon NanoTube (CNT) Cathodes at RadiaBeam vacuum, gun, high-voltage, electron 1590
 
  • L. Faillace, R.B. Agustsson, S. Boucher, A.Y. Murokh, A.V. Smirnov
    RadiaBeam, Santa Monica, USA
  
  RadiaBeam is developing Carbon Nanotube (CNT) cathodes for DC-pulsed and radio frequency (RF) driven electron sources. CNT cathodes, if realized, are capable of producing very high current density with low thermal emittance, due to ambient operating temperature. The initial experimental results of CNT cathodes are presented, including the high-voltage tests, and life time studies. CNT cathodes potential applications in accelerator science and microwave industry are discussed, and near term plans to test the CNT cathodes in the RF environment are presented.  
 
TUPPD082 Simulations of Multipacting in the Cathode Stalk and FPC of 112 MHz Superconducting Electron Gun electron, gun, simulation, niobium 1593
 
  • T. Xin, X. Liang
    Stony Brook University, Stony Brook, USA
  • S.A. Belomestnykh, I. Ben-Zvi, T. Rao, J. Skaritka, E. Wang, Q. Wu
    BNL, Upton, Long Island, New York, USA
  • X. Chang
    Far-Tech, Inc., San Diego, California, USA
  
  Funding: Work is supported at BNL by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE. The work at Stony Brook is supported by the US DOE under grant DE-SC0005713.
A 112 MHz superconducting quarter-wave resonator electron gun will be used as the injector of the Coherent Electron Cooling (CEC) proof-of-principle experiment at BNL. Furthermore, this electron gun can be used for testing of the performance of various high quantum efficiency photocathodes. In a previous paper, we presented the design of the cathode stalks and a Fundamental Power Coupler (FPC). In this paper we present updated designs of the cathode stalk and FPC. Multipacting in the cathode stalk and FPC was simulated using three different codes, Multipac, CST particle studio and FishPact respectively. All simulation results show no serious multipacting in the cathode stalk structure and FPC. 		 
 
TUPPP060 Injector Design for PAL-XFEL Project gun, laser, emittance, solenoid 1732
 
  • J.H. Han, M.S. Chae, J.H. Hong, I. Hwang, H.-S. Kang, I.S. Ko, S.J. Park
    PAL, Pohang, Kyungbuk, Republic of Korea
  
  Funding: The Ministry of Education, Science and Technology of the Korean Government
The PAL-XFEL project has the baseline specification of FEL radiation down to 0.1 nm with a 10 GeV S-band normal conducting linac. To fulfill the requirement of the beam parameter, the S-band photoinjector was designed. Numerical optimizations for nominal and low charge operations are presented. 		 
 
WEOAB02 Photocathode R&D at Cornell University electron, vacuum, emittance, gun 2137
 
  • L. Cultrera, I.V. Bazarov, J.V. Conway, B.M. Dunham, Y. Hwang, Y. Li, X. Liu, R. Merluzzi, T.P. Moore, K.W. Smolenski
    CLASSE, Ithaca, New York, USA
  • S.S. Karkare, J.M. Maxson, W.J. Schaff
    Cornell University, Ithaca, New York, USA
  
  Funding: This work has been supported by NSF DMR-0807731 and by DOE DE-SC0003965.
A wide R&D program is pursued at Cornell University aimed at preparation and characterization of high efficiency photocathodes for the Energy Recovery Linac photoinjector. The currently investigated photoemitters include both positive and negative electron affinity materials such as respectively bi-alkali antimonide and III-V semiconductors activated with Cs and either O or F. Analysis techniques as Scanning Auger Spectroscopy, Low Energy Electron Diffraction, Reflected High Energy Electron Diffraction and work function measurements are used to characterize the surfaces properties of the specimens. Spectral response, photoemission uniformity, electron energy distributions are used to characterize the quality of the photoelectron beam and to relate it to the measured surface properties. 		 
slides icon Slides WEOAB02 [6.934 MB]  
 
WEEPPB004 Status of the APEX Project at LBNL gun, cavity, laser, electron 2173
 
  • F. Sannibale, B.J. Bailey, K.M. Baptiste, J.M. Byrd, C.W. Cork, J.N. Corlett, S. De Santis, L.R. Doolittle, J.A. Doyle, P. Emma, J. Feng, D. Filippetto, G. Huang, H. Huang, T.D. Kramasz, S. Kwiatkowski, W.E. Norum, H.A. Padmore, C. F. Papadopoulos, G.C. Pappas, G.J. Portmann, J. Qiang, D.G. Quintas, J.W. Staples, T. Vecchione, M. Venturini, M. Vinco, W. Wan, R.P. Wells, M.S. Zolotorev, F.A. Zucca
    LBNL, Berkeley, California, USA
  • M. J. Messerly, M.A. Prantil
    LLNL, Livermore, California, USA
  • C.M. Pogue
    NPS, Monterey, California, USA
  
  Funding: This work was supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231.
The Advanced Photo-injector Experiment (APEX) at the Lawrence Berkeley National Laboratory is focused on the development of a high-brightness high-repetition rate (MHz-class) electron injector for X-ray FEL applications. The injector is based on a new concept gun, utilizing a normal conducting 186 MHz RF cavity operating in cw mode in conjunction with high quantum efficiency photocathodes capable of delivering the required repetition rates with available laser technology. The APEX activities are staged in 3 main phases. In Phases 0 and I, the gun will be tested at its nominal energy of 750 keV and several different photocathodes are tested at full repetition rate. In Phase II, a pulsed linac will be added for accelerating the beam at several tens of MeV to reduce space charge effects and measure the high-brightness performance of the gun when integrated in an injector scheme. At Phase II energies, the radiation shielding configuration of APEX limits the repetition rate to a maximum of several Hz. Phase 0 is under commissioning, Phase I under installation, and initial activities for Phase II are underway. This paper presents an update on the status of these activities. 		 
 
WEEPPB007 Initial Testing of the Mark-0 X-band RF Gun at SLAC gun, solenoid, vacuum, radiation 2179
 
  • A.E. Vlieks, C. Adolphsen, V.A. Dolgashev, J.R. Lewandowski, C. Limborg-Deprey, S.P. Weathersby
    SLAC, Menlo Park, California, USA
  
  A new X band RF Gun (Mark-0) has been assembled, tuned and is being tested in the ASTA facility at SLAC. This gun has been improved from an earlier gun used in Compton-scattering experiments at SLAC by the introduction of a racetrack dual-input coupler to reduce quadrupole fields. Waveguide-to-coupler irises were also redesigned to reduce surface magnetic fields and therefore peak pulse surface heating. Tests of this photocathode gun will allow us to gain early operational experience for beam tests of a new gun with further improvements (Mark-1) being prepared for SLAC’s X-Band Test Accelerator (XTA) program and the LLNL MegaRay program. Results of current testing up to ≈ 200 MV/m peak surface Electric fields will be presented.  
 
WEPPC111 Multipacting Simulation ADN Test Results of BNL 704 MHz SRF Gun cavity, gun, SRF, simulation 2480
 
  • W. Xu, S.A. Belomestnykh, I. Ben-Zvi, C. Cullen, H. Hahn, X. Liang, G.T. McIntyre, D. Pate, S.P. Pontieri, C. Schultheiss, T. Seda, T.N. Tallerico, R. Than, R.J. Todd, S.J. Tuozzolo, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
  • J. Dai
    SBU, Stony Brook, New York, USA
  • L.R. Hammons
    Stony Brook University, Stony Brook, USA
  
  Funding: This work was supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE.
The BNL 704 MHz SRF gun has a grooved choke joint to support the photo-cathode. Due to the distortion of grooves at the choke joint during the BCP for the choke joint, several multipacting barriers showed up when it was tested with Nb cathode stalk at JLab. We built a setup to use the spare large grain SRF cavity to test and condition the multipacting at BNL with various power sources. The test is carried out with three steps: cavity, cavity with Nb cathode stalk, and cavity with copper cathode stalk. This paper summarizes the results of multipacting simulation, and presents large grain cavity test setup and the test results. 		 
 
WEPPD054 Development of Pulsed Laser Systems and Cathode-performance Studies for the S-DALINAC Polarized Injector laser, electron, cavity, vacuum 2642
 
  • M. Espig, C. Eckardt, J. Enders, Y. Fritzsche, N. Kurichiyanil, J. Lindemann, M. Wagner
    TU Darmstadt, Darmstadt, Germany
  
  A source of polarized electrons has recently been implemented at the superconducting Darmstadt electron linear accelerator S-DALINAC. We give an overview of the recent performance of the system. Photo-emission from a superlattice-GaAs photo-cathode is obtained from using either a DC diode laser or a short-pulse Ti:Sapphire laser system. For a robust pulsed quasi-cw operation, it is investigated whether a VECSEL system (Vertical-Cavity Surface-Emitting Laser) can be realized with a wavelength of 780 nm and a repetition rate of 3 GHz with pulse widths of a few picoseconds only. To enhance the availability and performance of the polarized source with respect to quantum efficiency, a separate atomic-hydrogen cleaning system for the cathodes is planned which will allow cathode treatment to be tested and optimized. Supported by DFG within CRC/SFB 634 and by the state of Hesse in the LOEWE-Center HIC for FAIR.  
 
WEPPD060 A Drive Laser for Multi-bunch Photoinjector Operation laser, electron, brightness, emittance 2657
 
  • D.J. Gibson, C.P.J. Barty, M. J. Messerly, M.A. Prantil
    LLNL, Livermore, California, USA
  • E. Cormier
    CELIA, Talence, France
  
  Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344
Numerous electron beam applications would benefit from increased average current without sacrificing beam brightness. Work is underway at LLNL to investigate the performance of X-band photoinjectors that would generate electron bunches at a rate matching the RF drive frequency, i.e. one bunch per RF cycle. A critical part of this effort involves development of photo-cathode drive laser technology. Here we present a new laser architecture that can generate pulse trains at repetition rates up to several GHz. This compact, fiber-based system is driven directly by the accelerator RF and so is inherently synchronized with the accelerating fields, and scales readily over a wide range of drive frequencies (L-band through X-band). The system will be required to produce 0.5 μJ, ~200 fs rise time, spatially and temporally shaped UV pulses designed to optimize the electron beam brightness. Presented is the current status of this system, producing pulses shorter than 2 ps from a cw source. 		 
 
WEPPD084 The E-Lens Test Bench for Rhic Beam-Beam Compensation electron, gun, controls, dipole 2720
 
  • X. Gu, Z. Altinbas, J.N. Aronson, E.N. Beebe, W. Fischer, D.M. Gassner, K. Hamdi, J. Hock, L.T. Hoff, P. Kankiya, R.F. Lambiase, Y. Luo, M. Mapes, J.-L. Mi, T.A. Miller, C. Montag, S. Nemesure, M. Okamura, R.H. Olsen, A.I. Pikin, D. Raparia, P.J. Rosas, J. Sandberg, Y. Tan, C. Theisen, P. Thieberger, J.E. Tuozzolo, W. Zhang
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
To compensate for the beam-beam effects from the proton-proton interactions at IP6 and IP8 in the Relativistic Heavy Ion Collider (RHIC), we are fabricating two electron lenses that we plan to install at RHIC IR10. Before installing the e-lenses, we are setting-up the e-lens test bench to test the electron gun, collector, GS1 coil, modulator, partial control system, some instrumentation, and the application software. Some e-lens power supplies, the electronics for current measurement will also be qualified on test bench. The test bench also was designed for measuring the properties of the cathode and the profile of the beam. In this paper, we introduce the layout and elements of the e-lens test bench; and we discuss its present status towards the end of this paper. 		 
 
WEPPP030 Experimental Generation of a Double-bunch Electron Beam by Transverse-to-Longitudinal Phase Space Exchange laser, electron, focusing, gun 2789
 
  • T.J. Maxwell, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • A.S. Johnson, A.H. Lumpkin, J. Ruan, Y.-E. Sun, R.M. Thurman-Keup
    Fermilab, Batavia, USA
  
  Funding: Supported by Fermi Research Alliance, LLC under U.S. Dept. of Energy Contract No. DE-AC02-07CH11359, and Northern Illinois Univ. under US Dept. of Defense DURIP program Contract N00014-08-1-1064.
In this paper we demonstrate the generation of a tunable, longitudinal double-pulse electron beam. Experimental results on the generation of electron bunch trains with sub-picosecond structure have been previously reported where an initial transverse electron beam modulation was produced by masking the electron beam directly*. Here the initial transverse structure is imparted by masking of the photoinjector drive laser to effectively produce two horizontally offset beams at photoemission in the RF gun. A longitudinal double-pulse modulation is then realized after a transverse-to-longitudinal phase-space exchange beamline. Longitudinal profile tuning is demonstrated by upstream beam focusing in conjunction with downstream monitoring of single-shot electro-optic spectral decoding of coherent transition radiation.
* Y.-E. Sun et al., Tunable Subpicosecond Electron-Bunch-Train Generation Using a Transverse-To-Longitudinal Phase-Space Exchange Technique, Phys. Rev. Lett. 105, 234801 (2010). 		 
 
WEPPP051 Excitation of Plasma Wakefields with Designer Bunch Trains plasma, wakefield, emittance, laser 2828
 
  • P. Muggli
    MPI, Muenchen, Germany
  • B.A. Allen, Y. Fang
    USC, Los Angeles, California, USA
  • M. Babzien, M.G. Fedurin, K. Kusche, R. Malone, C. Swinson, V. Yakimenko
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by US Department of Energy.
Plasma can sustain multi-GV/m longitudinal electric fields that can be used for particle acceleration. In the plasma wakefield accelerator, or PWFA, the wakefields are driven by a single or a train of electron bunches with length comparable to the plasma wavelength. A train of bunches resonantly driving the wakefields can lead to energy gain by trailing particles many times the energy of the incoming drive train particles (large transformer ratio). In proof-of-principle experiments at the Brookhaven National Laboratory Accelerator Test Facility, we demonstrate by varying the plasma density over four orders of magnitude, and therefore the accelerator frequency over two orders of magnitude (~100GHz to a few THz), that trains with ~ps period resonantly drive wakefields in ~1016/cc density plasmas. We also demonstrate energy gain by a trailing witness electron bunch that follows the drive train with a variable delay. Detailed experimental results will be presented. 		 
 
THPPC027 Measurement of the Dynamic Response of the CERN DC Spark System and Preliminary Estimates of the Breakdown Turn-on Time simulation, impedance, vacuum, radio-frequency 3338
 
  • N.C. Shipman, R.M. Jones
    UMAN, Manchester, United Kingdom
  • S. Calatroni, W. Wuensch
    CERN, Geneva, Switzerland
  
  The new High Rep Rate (HRR) CERN DC Spark System has been used to investigate the current and voltage time structure of a breakdown. Simulations indicate that vacuum breakdowns develop on ns timescales or even less. An experimental benchmark for this timescale is critical for comparison to simulations. The fast rise time of breakdown may provide some explanation of the particularly high gradients achieved by low group velocity, and narrow bandwidth, accelerating structures such as the T18 and T24. Voltage and current measurements made with the previous system indicated that the transient responses measured were dominated by the inherent capacitances and inductances of the DC spark system itself. The bandwidth limitations of the HRR system are far less severe allowing rise times of around 12ns to be measured.  
 
THPPC042 Modified Magnicon for High-Gradient Accelerator R&D cavity, gun, electron, solenoid 3377
 
  • S.V. Shchelkunov, Y. Jiang, M.A. LaPointe
    Yale University, Beam Physics Laboratory, New Haven, Connecticut, USA
  • J.L. Hirshfield
    Omega-P, Inc., New Haven, USA
  • V.P. Yakovlev
    Fermilab, Batavia, USA
  
  Funding: Research supported by the U.S. Department of Energy, Office of High Energy Physics
A self-consistent design is described of a modified 34.3 GHz magnicon amplifier with a TE311-mode output cavity, to replace the existing magnicon at Yale Beam Physics Lab Test Facility whose output cavity operates in the TM310 mode. The main goal for the new design is to achieve robust reliable operation. This is expected since tube performance – according to simulations – is largely insensitive to the magnitude of external dc magnetic fields, including imperfections in magnetic field profile; small changes in gun voltage and current; changes in electron beam radial size; and even poorly matched external circuitry. The new tube, as with its predecessor, is a third harmonic amplifier, with drive and deflection gain cavities near 11.424 GHz and output cavity at 34.272 GHz. The design calculations predict stable output of power of 20-27 MW at a 10 Hz repetition rate in pulses up to 1.3 μs long, with a low probability of breakdown in the output cavity because of low electric fields (less than 650 kV/cm). 		 
 
THPPC048 Innovative Low-Energy Ultra-Fast Electron Diffraction (UED) System electron, gun, vacuum, high-voltage 3395
 
  • L. Faillace, S. Boucher
    RadiaBeam, Santa Monica, USA
  • P. Musumeci
    UCLA, Los Angeles, California, USA
  
  Funding: Work supported by DOE.
RadiaBeam, in collaboration with UCLA, is developing an innovative, inexpensive, low-energy ultra-fast electron diffraction (UED) system which allows us to reconstruct a single ultrafast event with a single pulse of electrons. Time resolved measurement of atomic motion is one of the frontiers of modern science, and advancements in this area will greatly improve our understanding of the basic processes in materials science, chemistry and biology. The high-frequency (GHz), high voltage, phase-locked RF field in the deflector allows temporal resolution as fine as 100 fs. In this paper, we show the complete design of a UED system based on this concept, including an optimized electron gun, a high-resolution RF deflector, and the post-interaction imaging system. 		 
 
THPPC055 Permanent Magnet Focusing System for Klystrons klystron, permanent-magnet, focusing, electron 3413
 
  • Y. Fuwa, Y. Iwashita, H. Tongu, S. Ushijima
    Kyoto ICR, Uji, Kyoto, Japan
  • S. Fukuda
    KEK, Ibaraki, Japan
  
  The Distributed RF System (DRFS) for ILC requires thousands of klystrons. The failure rate of the power supply for solenoid focusing coil of each klystron may be harmful to a regular operation of the ILC. In order to eliminate the power supplies and the cooling system for the coils, a permanent magnet beam focusing system is under development. It will help to reduce the power consumption as well. In our design, a unidirectional magnetic field configuration is adopted to eliminate the stop bands that arise from the periodic permanent magnet configuration. Since the required magnetic field is not high in this case, inexpensive anisotropic ferrite magnets can be used instead of magnets containing rare earth materials. On the basis of a half scaled model fabricated to evaluate the mechanical design, a full scaled model will be ready soon. In order to prove its feasibility, a power test of the klystron for DRFS with this magnet system is planned. The result of magnetic field distribution measurement and the power test will be presented.  
 
THPPC062 CPI 100kW Klystrons Operation Experiences in NSRRC klystron, factory, cavity, power-supply 3434
 
  • T.-C. Yu, L.-H. Chang, M.H. Chang, L.J. Chen, F.-T. Chung, M.-C. Lin, Y.-H. Lin, C.H. Lo, M.H. Tsai, Ch. Wang, T.-T. Yang, M.-S. Yeh
    NSRRC, Hsinchu, Taiwan
  
  In 2004, NSRRC had decided to upgrade its traditional copper cavity in storage ring of Taiwan Light Source (TLS) to superconducting cavity for higher beam current, brighter X-ray and more insertion devices. To achieve this, the RF power source-the klystron had been upgraded by intensive cooperation with CPI (Communication & Power Industries) from 70 kW to 100 kW. The same 100 kW klystron would then be also adopted as the RF source in booster in TPS plan. There are total five 100kW CPI klystrons with Model number of VKB-7953B as the power amplifiers in RF facility of NSRRC. Four of the five klystrons have been tested in detail as basic characteristic understanding in custom test stand. Some encountered phenomenon in testing period would be discussed here. In conclusion, these klystrons from CPI is quite load VSWR sensitive while the performance has large difference between them.  
 
THPPC065 Phase and Frequency Locked Magnetron cavity, shielding, controls, interaction-region 3440
 
  • M.L. Neubauer, A. Dudas, R. Sah
    Muons, Inc, Batavia, USA
  • A. Moretti, M. Popovic
    Fermilab, Batavia, USA
  
  Funding: Supported in part by SBIR Grant 4724 · 09SC02766
Phase and Frequency locked magnetrons have many important uses from phased array ground penetrating radars to SRF sources. We report on the recent progress in making such a magnetron. The ferrite/garnet material has passed bakeout and outgassing tests with outgassing rates well below the requirements. The magnetic field requirements for adjusting the frequency by changing the microwave properties of the ferrite/garnet have been determined. The design of the anode structure with ferrites, magnetic shielding, and magnetic bias has been completed for a low power test. We report on the design status. Muons, Inc. has negotiated an contract with a manufacturing firm, L-3 Electron Devices California Tube Laboratory, Inc., to be the Manufacturing Partner for the commercialization of this technology and support these Phase II efforts. 		 
 
THPPC069 Design, Test and Implementation of New 201.25 MHz Power Amplifier for the LANSCE Linac DTL, electron, HOM, cavity 3446
 
  • J.T.M. Lyles, Z. Chen, J. Davis, A.C. Naranjo, D. Rees, G. M. Sandoval, Jr.
    LANL, Los Alamos, New Mexico, USA
  • D. Baca, R.E. Bratton, R.D. Summers
    Compa Industries, Inc., Los Alamos, New Mexico, USA
  • N.W. Brennan
    Texas A&M University, College Station, Texas, USA
  
  Funding: Work supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396
A new 201.25 MHz final power amplifier (FPA) has been designed, fabricated, and tested at Los Alamos Neutron Science Center (LANSCE). The prototype FPA has produced 3 MW peak and 250 kW of mean power with 15 dB of power gain and over 60% efficiency. It has been tested for several thousand hours with a load. A Thales TH628 Diacrode® electron tube is key to the performance of the new amplifier. It is configured with a full wavelength output circuit, having the lower main tuner situated ¾λ from the central electron beam region in the tube and the upper slave tuner ¼λ from the same point. The FPA is designed with input and output transmission line cavity circuits, grid decoupling circuits, an adjustable output coupler, DC blocking and RF bypassing capacitors, HOM suppressors, and a cooling system. A pair of production amplifiers are planned to be power-combined for up to 3.6 MW peak power at high duty factor. Three of these combined amplifiers will be installed in place of the original 1968-vintage amplifiers to return LANSCE operation to 12% beam duty factor with higher peak current than presently possible. 		 
 
THPPC083 Investigation of Feedback Control for Klystron Ripple cavity, feedback, klystron, controls 3479
 
  • R. Zeng, D.P. McGinnis, S. Molloy
    ESS, Lund, Sweden
  • A.J. Johansson
    Lund University, Lund, Sweden
  
  At ESS (European Spallation Source), there might be potentially serious droop and ripple because of long RF pulse more than 3 ms. It is important for us to know to what extent the droop and ripple affects the klystron output, and how much we can tolerate. The variations of the phase and amplitude of klystron output due to the change in klystron cathode voltage is investigated in this Paper. The mechanism and the effectiveness of the feedback control to suppress the variations are given. To understand the limitation of the feedback, both proportional controller and proportional-integral controller used in feedback loop are simulated and analyzed respectively for superconducting cavity and normal conducting cavity. The tolerances of the droop and ripple in cathode voltage under feedback control are shown according to the data and results obtained.  
 
THPPD070 Design of High Power Pulse Modulator for Driving of Twystron used in S-band Linear Accelerator electron, vacuum, klystron, power-supply 3674
 
  • V. Aslani, F. AbbasiDavani, F. Ghasemi, M.Sh. Shafiee
    sbu, Tehran, Iran
  
  This design related to an s-band linear accelerator that the main tube and buncher of it have been made. RF power supply is used in this accelerator tube made up of a Twystron with 2.5 MW peak power and frequency band width 2.9~3.1 GHz. This paper offers the design of modulator for this RF amplifier. This modulator design uses solid-state method and is under construction with specification of ; Adjustable voltage from 0 to 120 kV, adjustable pulse width 2 until7μsecond, adjustable repetition rate 80-120 Hz ,ripple less than0.25% and efficiency up 80 percent. This system designed with series of 6 modules that each of them provides 5kV and IGBT switches that transform the voltage on the pulse transformer.  
 
THPPD077 ISIS Injector 2 MW Pulsed RF System Power Supply Upgrade controls, linac, simulation, power-supply 3695
 
  • R.J. Anderson
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  • M. Keelan
    STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
  
  The ISIS pulsed neutron and muon source uses a 4-stage 70 Mev linear accelerator powered by TH116 triode valves. The TH116 anode supply capacitor banks have until recently been supplied by conventional 6-pulse silicon controlled rectifier (SCR) bridges delivering up to 40 kV at 5 A direct current. This dated system has become increasingly difficult to maintain. Early trials of an upgraded system using modern, compact, capacitor charging, switch mode supplies (SMPSs) resulted in severe supply power quality issues due to the pulsed nature of the current demanded from the capacitor banks. Measurements and Spice simulations of the old and replacement supplies allowed the power quality issues to be investigated and an additional external-to-the-SMPS regulator control loop to be developed. The new SMPSs operating with the additional control loop have been tested successfully on several of the linear accelerator stages and are now in continuous operational use. The process of replacing all the original SCR 6-pulse bridges is now well advanced and the operational benefits for ISIS are becoming evident.  
 
THPPD078 Cold Cathode Thyratron Based High-voltage Kicker Generators at the Duke Accelerators: Six Year Experience kicker, power-supply, extraction, high-voltage 3698
 
  • V. Popov, S.F. Mikhailov, P.W. Wallace, Y.K. Wu
    FEL/Duke University, Durham, North Carolina, USA
  
  Funding: This work is supported in part by the US DOE grant #DE-FG02-97ER41033.
The performance of the Duke storage ring based light sources, the Duke storage ring FEL and High Intensity Gamma-ray Source (HIGS), has been greatly improved since 2007 as the result of operating a new full-energy, top-off booster injector (0.18 - 1.2 GeV), allowing fixed energy operation of the storage ring (0.25 - 1.2 GeV). The injection/extraction kicker system is one of the key components of the accelerator facility which determines efficiency and reliability of the light source operation. Pseudo-Spark Switches(PSS), also known as cold cathode thyratrons, are the critical components of the high voltage pulse generators for kickers. More than six years of operation has allowed us to study the lifetime issue for the 10 kA class devices. Recently, we have tested the next generation cold cathode thyratron, with one installed in one of our storage ring kicker high voltage generators. In the present paper we will also present preliminary test results of this new thyratron and the required modifications of its triggering driver to improve its performance. 		 
 
THPPD081 Droop Compensation for the High Voltage Converter Modulators at the Spallation Neutron Source high-voltage, controls, klystron, LLRF 3704
 
  • G. Patel, D.E. Anderson, D.J. Solley, M. Wezensky
    ORNL, Oak Ridge, Tennessee, USA
  
  Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725
The Spallation Neutron Source (SNS) has been in operation since 2006 and has demonstrated up to 1 MW of beam power. At 1MW, the High Voltage Converter Modulators (HVCMs) are delivering 11MW pulsed power to the Klystrons for 1185us at 60 Hz. The pulsed output of the modulator has a substantial voltage droop. The future operational goals of the accelerator involve delivering 1.4 MW to the target. This implies an increase in the output pulse width of the HVCM, resulting in loss of RF control from inadequate control margin for LLRF systems due to modulator voltage reduction at the end of pulse. Initially, the HVCM was designed with a pulse width modulation scheme for droop compensation but early operations revealed this technique unreliable for full power operation. Increasing the output voltage of the modulator would likely compromise system reliability. This paper proposes the use of alternate modulation schemes to address the voltage droop. The effect of frequency modulation and phase shift modulation on output pulse is studied and concludes by selecting an optimum modulation algorithm to be implemented. Experimental results will also be presented. 		 
 
THPPR049 Study on Electron Microbeam Generation for MRT Based on Photo-cathode RF-Gun gun, electron, laser, radiation 4086
 
  • Y. Yoshida, K. Sakaue, M. Washio
    RISE, Tokyo, Japan
  
  We have been developing an MRT (Microbeam Radiation Therapy) based on Cs-Te photo cathode RF-Gun at Waseda University. MRT is proposed to treat tumor by using array of several micro-meter parallel beams. In this therapy, irradiated normal tissue repairs itself, by contrast, even a non-irradiated tumor tissue dies. In the other words, the microbeam enhances the radiation sensitivity difference between normal and tumor issues. Therefore, MRT is considered one of the most useful tumor therapies in the future. We have generated electron microbeam by tungsten collimator slit and analyzed their dose distribution in air and in the PMMA phantom. We have used radiochromic film called GAFCHROMIC dosimetry film type HD-810 to measure them. We have compared these experimental results with Monte Carlo simulation of the dose distribution using the EGS5 code. In this conference, we would like to report the electron microbeam procedure, optimization of irradiation condition, evaluation of microbeam specifications and future prospects.  
 
THPPR059 Progress of the Equivalent Velocity Spectroscopy Method for Femtosecond Pulse Radiolysis by Pulse Rotation and Pulse Compression electron, laser, radiation, linac 4109
 
  • T. Kondoh, K. Kan, K. Norizawa, A. Ogata, S. Tagawa, J. Yang, Y. Yoshida
    ISIR, Osaka, Japan
  • H. Kobayashi
    KEK, Ibaraki, Japan
  
  Femtosecond pulse radiolysis is developed for studies of electron beam induced ultra-fast reaction in matter. 98 fs electron pulse was generated by a photocathode RF gun LINAC with a magnetic bunch compressor. However for more fine time resolution, the Equivalent velocity spectroscopy (EVS) method is required to avoid degradation of time resolution caused by velocity difference between electron and analysing light in sample. In the EVS method, incident analysing light is oblique toward electron beam with an angle associated with refractive index of sample, and then, electron pulse is rotated toward the direction of travel to overlap with light pulse. In previous studies, pulse rotation had not been compatible with pulse compression. However, by oblique incident of light to the photocathode, pulse rotation was compatible with pulse compression, and the time resolution was improved by principle of the equivalent velocity spectroscopy.  
 
FRXBA01 Overview of Recent Progress on High Repetition Rate, High Brightness Electron Guns gun, electron, SRF, brightness 4160
 
  • F. Sannibale
    LBNL, Berkeley, California, USA
  
  In the last few years, the formidable results of x-ray light sources based on FELs opened the door to classes of experiments not accessible before. Operating facilities have relatively low repetition rates (~ 10-100 Hz), and the natural step forward consists in the development of FEL light sources capable of extending their rates by orders of magnitude in the MHz regime. Additionally, ERL based x-ray facilities with their promise of outstanding performance also require extremely high, GHz-class repetition rates. The development of such facilities would represent the next revolutionary step in terms of science capability. To operate such light sources, an electron injector capable of MHz/GHz repetition rates and with the brightness required by X-ray FELs or ERLs is required. Such injector presently does not exist. In response to that, many groups around the world are intensively working on different schemes and technologies that show the potential for achieving the desired results. This presentation includes a description of the requirements for such injectors, an overview of the pursued technologies, and a review of the results obtained so far by the groups active in the field.  
slides icon Slides FRXBA01 [6.290 MB]  
 
FRXBB01 Femtosecond Electron Guns for Ultrafast Electron Diffraction electron, gun, emittance, laser 4170
 
  • J. Yang, K. Kan, T. Kondoh, N. Naruse, K. Tanimura, Y. Yoshida
    ISIR, Osaka, Japan
  • J. Urakawa
    KEK, Ibaraki, Japan
  
  This talk should describe the development of electron guns for producing femtosecond electron pulses with low (<0.1 micron) emittance, for ultrafast electron diffraction. Comparisons should be made between the systems developed by groups in Asia, Europe and America, outlining any similarities and contrasts. The focus should be on the technology for generating, accelerating, and controlling the bunches, but some description of the science applications should also be included. Finally, prospects for future developments should be considered.  
slides icon Slides FRXBB01 [7.004 MB]