Keyword: cathode
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MOOCA3 Amorphous Carbon Thin Film Coating of the SPS Beamline: Evaluation of the First Coating Implementation vacuum, electron, proton, operation 44
 
  • M. Van Gompel, P. Chiggiato, P. Costa Pinto, P. Cruikshank, C. Pasquino, J. Perez Espinos, A. Sapountzis, M. Taborelli, W. Vollenberg
    CERN, Geneva, Switzerland
  
  As part of the LHC Injector Upgrade (LIU) project, the Super Proton Synchrotron (SPS) must be upgraded in order to inject in the LHC 25 ns bunch spaced beams of higher intensity. To mitigate the Electron Multipacting (EM) phenomenon in the SPS, CERN developed thin film carbon coatings with a low Secondary Electron Yield (SEY). The development went from coating small samples, up to coating of 6 m long vacuum chambers directly installed in the magnets. To deposit the low SEY amorphous carbon (aC) film on the vacuum chamber inner wall of SPS ring components, a modular hollow cathode train was designed. The minimization of the logistical impact requires a strategy combining in-situ and ex-situ coating, depending on the type of components. To validate the implementation strategy of the aC thin films and the in-situ coating process along the 7 km long SPS beamline, approximately 2 cells of B-type bending dipoles and 9 focussing quadrupoles are foreseen to be treated with the aC coating during the Extended Year End Technical Stop (EYETS) 2016-2017. We will discuss the coating technique and evaluate both the implementation process and the resulting coating performance.  
slides icon Slides MOOCA3 [71.421 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOOCA3  
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MOPIK003 Improvement of the Photoemission Efficiency of Magnesium Photocathodes gun, SRF, laser, cavity 500
 
  • R. Xiang, A. Arnold, P.N. Lu, P. Michel, P. Murcek, J. Teichert, H. Vennekate
    HZDR, Dresden, Germany
  • P. Patra
    IUAC, New Delhi, India
  
  Funding: The work is supported by the European Community under the FP7 programme (EuCARD-2) and by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1.
To improve the quality of photocathodes is one of the critical issues in enhancing the stability and reliability of photo-injector systems. Presently the primary choice is to use metallic photocathodes for the ELBE SRF Gun-II to reduce the risk of contamination of the superconducting cavity. Magnesium has a low work function (3.6 eV) and shows high quantum efficiency (QE) up to 0.3 % after laser cleaning. The SRF Gun II with an Mg photocathode has successfully provided electron beam for ELBE users. However, the present cleaning process with a high intensi-ty laser (activation) is time consuming and generates unwanted surface roughness. This paper presents the investigation of alternative surface cleaning procedures, such as thermal treatment. The QE and topography of Mg samples after treatment are reported. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK003  
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MOPIK008 Numerical Studies on a Modified Cathode Tip for the ELBE Superconducting RF Gun electron, SRF, gun, simulation 515
 
  • E.T. Tulu, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • A. Arnold
    HZDR, Dresden, Germany
  
  Future light sources such as synchrotron radiation sources driven by an Energy Recovery Linac (ERL), Free Electron Laser (FEL) or THz radiation sources have in common that they require injectors, which provide high-brilliance, high-current electron beams in almost continuous operation. Thus, the development of appropriate highly brilliant electron sources is a central factor. A promising approach for this key component is provided by superconducting radiofrequency photoinjectors (SRF guns) [*]. Since 2007, the free-electron laser FELBE at HZDR successfully operates such a SRF gun under real conditions and equipped with all components [**]. Nevertheless, there are limitations caused by multipacting which should be overcome in order to further improve the gun [***]. One aspect in order to reach this aim lies in studying various modifications of the cathode tip [****]. This contribution will present the effectiveness of isosceles triangular grooves with respect to MP.
* Arnold, et al., NIM A, 593, 57, (2008).
** J. Teichert, et al., 2008 NSS/MIC, Dresden, Germany.
*** J. Teichert, et al., J. Phys.: Conf. Ser. 298(2011), 012008.
**** E. T. Tulu, et al., IPAC2014, p652, Dresden, Germany. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK008  
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MOPIK019 Upgrade Options Towards Higher Fields and Beam Energies for Continuous-Wave Room-Temperature VHF RF Guns gun, brightness, electron, cavity 542
 
  • F. Sannibale, J.M. Byrd, D. Filippetto, M.J. Johnson, D. Li, T.H. Luo, C.E. Mitchell, J.W. Staples, S.P. Virostek
    LBNL, Berkeley, California, USA
  
  Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231
Science demand for MHz-class repetition rate electron beam applications such as free electron lasers (FELs), inverse Compton scattering sources, and ultrafast electron diffraction and microscopy (UED/UEM), pushed the development of new gun schemes that could generate high brightness beams at such high rates. At the Lawrence Berkeley Lab (LBNL), we proposed a new concept room-temperature RF gun resonating in the VHF frequency range (30-300 MHz) capable of operating in continuous wave mode at the fields required for high-brightness performance. A first VHF-Gun was constructed and tested in the APEX facility at LBNL, which successfully demonstrated all design parameters and the generation of high brightness electron beams. A second version of the APEX VHF-Gun is being built at LBNL for the LCLS-II, the new SLAC X-ray FEL. Recent studies showed that a proposed LCLS-II upgrade and UED/UEM applications would greatly benefit from an increased gun brightness obtained by raising the electric field at the cathode and the beam energy at the gun exit. In this paper, we present and discuss possible upgrade options that would allow extension of the VHF-Gun performance towards these new goals. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK019  
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MOPIK021 Generation of Transversely Segmented Beam Using a Nano-Patterned Photocathode laser, simulation, gun, acceleration 545
 
  • A. Lueangaramwong, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • G. Andonian
    RadiaBeam, Santa Monica, California, USA
  • P. Piot
    Fermilab, Batavia, Illinois, USA
  
  Funding: Work supported by US Department of Energy (DOE) contract DE-SC0009656 with Radiabeam Technologies and by NSF grant PHY-1535401 with Northern Illinois University.
Plasmonic photocathodes – nano-patterned photocathodes with periodicity comparable to the excitation laser – have demonstrated enhanced quantum efficiency. In the present paper we present numerical simulations of the beam dynamics associated to the emission process from this type of cathodes and to the subsequent acceleration to relativistic energies by combining WARP and IMPACT-T programs. We especially consider the possibility to transversely image the cathode surface at high energy and enable the generation of transversely segment beams. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK021  
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MOPIK022 Experimental Investigation of Field-Emission From Silicon Nano-Cone Cathodes electron, emittance, vacuum, ion 548
 
  • A. Lueangaramwong, C. Buzzard, V. Korampally, O. Mohsen, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • S. Chattopadhyay
    Northern Illinois Univerity, DeKalb, Illinois, USA
  • R. Divan
    Argonne National Laboratory, Argonne, Illinois, USA
  • P. Piot
    Fermilab, Batavia, Illinois, USA
  
  Funding: This work is supported by the NSF grant PHY-1535401 with Northern Illinois University
Field emission cathode are capable of forming electron beam with extreme brightness via strong-field excitation from applied electrostatic, or electromagnetic (radiofrequency and laser) fields. Our group, in collaboration with the Argonne Center for Nanoscale Material, has recently developed nanocone cathode. The present paper reports on the experimental characterization of these cathodes both configured as a single-cone emitter or as large arrays of tightly-packed emitter. The tests carried in a diode setup are capable of measuring IV characteristic curves and beam distributions. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK022  
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MOPIK023 Cornell Laboratory for High Intensity, Ultra-Bright and Polarized Electron Beams electron, gun, simulation, ion 551
 
  • L. Cultrera, A.C. Bartnik, I.V. Bazarov, C.M. Gulliford, P. Gupta, H. Lee, S.A. McBride, T.P. Moore
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Funding: This work has been funded by the National Science Foundation (Grant No. PHY-1416318) and Department of Energy (Grants No. DE-SC0014338, No. DE-SC0011643 and No. DE-SC0016203).
We report on the current activities pursued at Cornell University for the production of electron beams tailored to a wide range of applications. We have developed the expertise to grow many different type of high quantum efficiency photocathode belonging to the alkali antimonide family. Those materials are ideal candidates to produce high intensity beam with average currents in the mA range. When operated near threshold at cryogenic temperature in transmission mode they can also generate the electron beams needed to perform ultrafast electron diffraction of bio molecules. We have recently expanded our facility with a Mott polarimeter to include the capability to measure polarization of the electron beam. The photocathode lab is being complemented by a dedicated photo-gun laboratory to test the photocathode properties in a real environment and to perform measurement of the beam properties under new and yet unexplored operating conditions. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK023  
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MOPIK075 Design, Simulation and Compare of Flat Cathode Electron Guns with Spherical Cathode Electron Guns for Industrial Accelerators gun, electron, simulation, space-charge 702
 
  • M. Nazari, F. Abbasi
    Shahid Beheshti University, Tehran, Iran
  • S. Ahmadiannamin
    ILSF, Tehran, Iran
  • F. Ghasemi
    NSTRI, Tehran, Iran
  • S. Haghtalab
    IPM, Tehran, Iran
  
  In this article, electron guns with flat and spherical cathodes have been designed and simulated for industrial accelerators. After checking the different features of each cathode geometry, there has been discussed about optimum values of this features. The most important features in selecting the best cathode geometry for industrial accelerators are beam waist radius, beam waist position, current density and price. Finally after comparing the different features of both geometries with each other, suitable geometry was selected.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK075  
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MOPIK098 Techniques for Achieving High Reliability Operation of the Spallation Neutron Source High Power Radio-Frequency System klystron, operation, cavity, neutron 756
 
  • J. Moss, M.S. Champion
    ORNL, Oak Ridge, Tennessee, USA
  
  Funding: *ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. This research was supported by the DOE Office of Science, Basic Energy Science, Scientific User Facilities.
The Spallation Neutron Source (SNS) high power radiofrequency (HPRF) system operates with high reliability to support the goals of the SNS user program. In recent operational periods the availability of the HPRF System has exceeded 97 percent while the neutron source availability overall is typically greater than 90 percent. SNS has a unique set of 92 HPRF stations that operate at either 402.5 MHz or 805 MHz with peak output power ranging from 550 kW to 5 MW and average power ranging from 49.5 kW to 450 kW. The HPRF transmitters consist of chassis-mounted power supplies, solid-state amplifiers and other equipment that support the operation of the klystrons that ultimately provide the RF power to the accelerating structures. Management of the operation and maintenance of the HPRF system has increasingly focused on reliability and sustainability in recent years. Techniques for klystron lifetime preservation and optimization of transmitter reliability have been developed and will be described. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK098  
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MOPIK111 Initial Performance Measurements of Multi-GHz Electron Bunch Trains electron, laser, emittance, gun 795
 
  • D.J. Gibson, R.A. Marsh
    LLNL, Livermore, California, USA
  • Y. Hwang
    UCI, Irvine, California, USA
  
  Funding: This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
LLNL's compact laser-Compton based x-ray source is currently producing up to 35 keV photons, with the capability to upgrade to 250 keV. Increasing the average brightness of such sources requires increasing the electron beam current. To avoid degradation of the narrow-bandwidth performance of the source, the per-bunch charge shouldn't increase; the effective repetition rate of the electron beams must be raised. It has been proposed* to generate bunch trains of several hundred pulses spaced by the period of X-band RF (~87 ps), which raises questions about beam-loading effects on the energy uniformity of the bunches and wakefield effects degrading the emittance of later bunches, compromising the x-ray quality. As a first test of this concept, we have installed into the electron-generating laser of our system optical pulse-stacking hardware to allow generation of 16-electron-bunch trains. Here we present the current status of our x-ray source, along with initial results using this new multi-bunch train. This includes characterization of collective electron beam energy spread and emittance growth.
* D.J. Gibson, et al., IPAC2012. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK111  
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MOPVA010 Setup and Status of an SRF Photoinjector for Energy-Recovery Linac Applications gun, SRF, laser, emittance 865
 
  • T. Kamps, D. Böhlick, A.B. Büchel, M. Bürger, P. Echevarria, A. Frahm, F. Göbel, S. Heling, A. Jankowiak, S. Keckert, H. Kirschner, G. Klemz, J. Knobloch, G. Kourkafas, J. Kühn, O. Kugeler, A.N. Matveenko, A. Neumann, N. Ohm-Krafft, E. Panofski, F. Pfloksch, S. Rotterdam, M.A.H. Schmeißer, M. Schuster, H. Stein, J. Ullrich, A. Ushakov, J. Völker
    HZB, Berlin, Germany
  • I. Will
    MBI, Berlin, Germany
  
  Funding: The work is funded by the Helmholtz-Association, BMBF, the state of Berlin and HZB.
The Superconducting RF (SRF) photoinjector programme for the energy-recovery linac (ERL) test facility BERLinPro sets out to push the brightness and average current limits for ERL electron sources by tackling the main challenges related to beam dynamics of SRF photoinjectors, the incorporation of high quantum efficiency (QE) photocathodes, and suppression of unwanted beam generation. The paper details the experimental layout of the SRF photoinjector and the gun test facility GunLab at Helmholtz-Zentrum Berlin. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA010  
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MOPVA021 Optics Design of the Compact ERL Injector for 60 pC Bunch Charge Operation optics, laser, operation, gun 898
 
  • T. Hotei
    Sokendai, Ibaraki, Japan
  • R. Kato, T. Miyajima, N. Nakamura, M. Shimada
    KEK, Ibaraki, Japan
  
  EUV-FEL light source based on ERL has been designed at KEK for EUV lithography light source. The advantage of ERL is to accelerate high average current beam due to CW operation, and it is possible to drive high average power FEL. To generate the target EUV-FEL power, which is 10 kW, the bunch charge of 60 pC, the beam energy of 10.5 MeV and the bunch length of 1 ps are required at the end of the EUV-FEL injector. In order to demonstrate the target beam performance for the EUV-FEL accelerator, a high charge beam test was carried out at the cERL in KEK. We designed a new optics of the cERL injector prior to the high charge beam operation. To calculate beam dynamics more accurately, accelerator models corrected according to the condition of the actual cERL injector is used for the optics design. From results of the optics design that minimized the emittance and bunch length using the corrected accelerator models, the emittance and bunch length at the end of injector are 0.8 mm-mrad and 3.4 ps. Furthermore, based on the design optics, we carried out high bunch charge beam operation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA021  
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MOPVA033 A Compact Thermionic RF Injector with RF Bunch Compression fed by a Quadrupole-Free Mode Launcher gun, electron, undulator, linac 924
 
  • F. Toufexis, V.A. Dolgashev, C. Limborg-Deprey, S.G. Tantawi
    SLAC, Menlo Park, California, USA
  
  Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515, and the National Science Foundation under Contract No. PHY-1415437.
We present a design for a compact X-Band RF thermionic injector consisting of two iris-loaded accelerator structures. Both structures are fed by a single quadrupole-free TM01 mode launcher. In the first structure the electron bunches are extracted from a thermionic cathode. The second structure creates an energy chirp in the bunch for its further ballistic compression. This injector can produce short electron bunches without the need for a magnetic bunch compressor. We are developing this injector as part of a linac-based 91.392 GHz RF power source, which further comprises a booster linac and a mm-wave decelerator structure that extracts 91.392 GHz RF power from the electron beam. This source will be used to power a short-period RF undulator with 1.75 mm period*.
* F. Toufexis and S.G. Tantawi, A 1.75 mm Period RF-Driven Undulator, these proceedings. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA033  
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MOPVA049 First Commissioning of an SRF Photo-Injector Module for BERLinPro cavity, SRF, solenoid, linac 971
 
  • A. Neumann, A. Burrill, D. Böhlick, A.B. Büchel, M. Bürger, P. Echevarria, A. Frahm, H.-W. Glock, F. Göbel, S. Heling, K. Janke, T. Kamps, S. Keckert, S. Klauke, G. Klemz, J. Knobloch, G. Kourkafas, J. Kühn, O. Kugeler, N. Ohm, E. Panofski, H. Plötz, S. Rotterdam, M. Schenk, M.A.H. Schmeißer, M. Schuster, H. Stein, Y. Tamashevich, J. Ullrich, A. Ushakov, J. Völker
    HZB, Berlin, Germany
  • A. Matheisen, M. Schmökel
    DESY, Hamburg, Germany
  
  Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Association.
Helmholtz-Zentrum Berlin (HZB) is currently building an high average current superconducting ERL to demonstrate ERL operation with low normalized beam emittance of 1 mm·mrad at 100mA and short pulses of about 2 ps. For the injector section a series of SRF photoinjector cavities is being developed. The medium power prototype presented here features a 1.4 x λ/2 cell SRF cavity with a normal-conducting, high quantum efficiency CsK2Sb cathode, implementing a modified HZDR-style cathode insert. This injector potentially allows for 6 mA beam current at up to 3.5 MeV kinetic energy. In this contribution, the first RF commissioning results of the photo-injector module will be presented and compared to the level of performance during the cavity production and string assembly process. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA049  
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MOPVA104 Physical Vapour Deposition of NbTiN Thin Films for Superconducting RF Cavities power-supply, SRF, target, superconductivity 1102
 
  • S. Wilde, B. Chesca
    Loughborough University, Loughborough, Leicestershire, United Kingdom
  • E. Alves
    Associação EURATOM/IST, Instituto de Plasmas e Fusão Nuclear, Lisboa, Portugal
  • N.P. Barradas
    Universidade de Lisboa, Instituto Superior Técnico, Bobadela, Portugal
  • A.N. Hannah, O.B. Malyshev, N. Pattalwar, S.M. Pattalwar, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • G.B.G. Stenning
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  
  The production of superconducting coatings for radio frequency cavities is a rapidly developing field that should ultimately lead to acceleration gradients greater than those obtained by bulk Nb RF cavities. The use of thin films made from superconductors with thermodynamic critical field, HC>HCNb, allows the possibility of multilayer superconductor ' insulator ' superconductor (SIS) films and accelerators that could operate at temperatures above the 2 K typically used. SIS films theoretically allow increased acceleration gradient due to magnetic shielding of underlying superconducting layers [1] and higher operating temperature can reduce cost [2]. High impulse magnetron sputtering (HiPIMS) and pulsed DC magnetron sputtering processes were used to deposit NbTiN thin films onto Si(100) substrate. The films were characterised using scanning electron microscopy (SEM), x-ray diffraction (XRD), Rutherford back-scattering spectroscopy (RBS) and a four-point probe.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA104  
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MOPVA115 Status and Challenges of Vertical Electro-Polishing R&D at Cornell cavity, niobium, SRF, linac 1115
 
  • F. Furuta, M. Ge, T. Gruber, D.L. Hall, J.J. Kaufman, M. Liepe, R.D. Porter, J. Sears
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • V. Chouhan, Y.I. Ida, K.N. Nii, T.Y. Yamaguchi
    MGH, Hyogo-ken, Japan
  • T.D. Hall, M.E. Inman, R. Radhakrishnan, S.T. Snyder, E.J. Taylor
    Faraday Technology, Inc., Clayton, Ohio, USA
  • H. Hayano, S. Kato, T. Saeki
    KEK, Ibaraki, Japan
  
  Advanced Vertical Electro-Polishing (VEP) R&D for SRF Niobium cavities continues at Cornell's SRF group. One focus of this work is new EP cathode development in collaboration with KEK and Marui Galvanizing Co. Ltd (Marui) in Japan, and another focus is on HF free or acid free VEP protocols in collaboration with Faraday Technology Inc. The outcomes of these activities could be a significant cost reduction and an environmentally-friendlier VEP, which would be a breakthrough for future large scale EP applications on SRF cavities. Here we give a status update and report latest results from these R&D activities.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA115  
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MOPVA140 Multipacting Behavior Study for the 112 MHz Superconducting Photo-Electron Gun cavity, gun, electron, SRF 1180
 
  • I. Petrushina
    SUNY SB, Stony Brook, New York, USA
  • V. Litvinenko, G. Narayan, I. Pinayev, F. Severino, K.S. Smith
    BNL, Upton, Long Island, New York, USA
  • V. Litvinenko
    Stony Brook University, Stony Brook, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Superconducting 1.2 MV 112 MHz quarter-wave photo-electron gun (SRF gun) is used as a source of electron beam for the Coherent electron Cooling experiment (CeC) at BNL. During the CeC commissioning we encountered a number of multipacting zones in the gun. It was also observed that introduction of CsK2Sb photocathode creates additional multipacting zone. This paper presents numerical and experimental study of the multipactor discharge in the SRF gun. We also discuss ways of crossing the multipacting levels to the operational voltage. Finally, we compare the results of our numerical simulations of the multipactor discharge using ACE3P with experimental data. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA140  
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TUPAB025 Experimental Results for Multiphoton Nonlinear Photoemission Processes on Phil Test Line laser, photon, electron, gun 1369
 
  • H. Purwar, C. Bruni, V. Chaumat, N. ElKamchi, V. Soskov
    LAL, Orsay, France
  • D. Garzella
    CEA, Gif-sur-Yvette, France
  • B. Lucas
    CNRS LPGP Univ Paris Sud, Orsay, France
  • M. Pittman
    CLUPS, Orsay, France
  • T. Vinatier
    DESY, Hamburg, Germany
  
  One of the prerequisites for the next generation high luminosity light sources is the availability of the short electron bunches. It also has several applications in other domains, including medical diagnostics and high-resolution imaging. In principle, using photoelectric effect a short electron bunch can initially be generated by illuminating a photocathode with an ultra-short light pulse of appropriate wavelength. Strong EM fields from a RF gun or similar accelerating structures, synchronized with the incoming laser pulses, are then used to accelerate these electron bunches initially up to an energy of tens of MeV. We present our preliminary results on the experimental investigation of two-photon nonlinear photoemission processes for the generation of picosecond, low-charge electron bunches conducted at PHIL photoinjector facility. A comparison of the emission efficiency and bunch characteristics with the single photon emission process is also made.
*PHIL is an acronym for Photo-injector at Linear Accelerator Laboratory (LAL). 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB025  
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TUPAB027 Production, Tuning and Processing Challenges of the BERLinPro Gun1.1 Cavity cavity, gun, niobium, SRF 1375
 
  • H.-W. Glock, A. Frahm, J. Knobloch, A. Neumann
    HZB, Berlin, Germany
  • B. Rosin, D. Trompetter
    RI Research Instruments GmbH, Bergisch Gladbach, Germany
  
  Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of the Helmholtz Association
For the BERLinPro energy recovery LINAC, HZB is developing a superconducting 1.4-cell electron gun, which, in its final version, is planned to be capable of CW 1.3 GHz operation with 77 pC/bunch. For this purpose a series of three superconducting cavities, denoted as Gun 1.0, Gun 1.1 (both designed for 6 mA) and Gun 2.0 (100 mA) are foreseen. Gun 1.0 now reached operational status and the Gun 1.1 cavity is completely manufactured. In the paper the chronology of manufacturing, tuning and processing of the Gun 1.1-cavity is described, also giving details about combined mechanical/electrodynamic simulations, which were performed in order to gain deeper understanding of the cavity's unexpected tuning behavior. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB027  
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TUPAB028 Measuring the Spectral Response of Cs-K-Sb Photocathodes for BERLinPro SRF, electron, linac, emittance 1378
 
  • H. Kirschner, A. Jankowiak, T. Kamps, J. Kühn, M.A.H. Schmeißer
    HZB, Berlin, Germany
  
  A spectral response setup was commissioned at the Cs-K-Sb photocathode preparation and analysis system developed for the BERLinPro project. The setup is designed to measure the spectral quantum efficiency from 370 to 700 nm and to monitor the photocurrent during the photocathode growth process and the photocathode lifetime at 515 nm.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB028  
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TUPAB029 UHV Photocathode Plug Transfer Chain for the BERLinPro SRF-Photoinjector SRF, vacuum, cavity, laser 1381
 
  • J. Kühn, J. Borninkhof, M. Bürger, A. Frahm, A. Jankowiak, T. Kamps, M.A.H. Schmeißer, M. Schuster
    HZB, Berlin, Germany
  • P. Murcek, J. Teichert, R. Xiang
    HZDR, Dresden, Germany
  
  A dedicated particle free UHV photocathode plug transfer chain from the preparation system to the SRF-Photoinjector was set up and commissioned at HZB for the BERLinPro project. The plug handling system was designed in collaboration with the ELBE team at HZDR, where the same transfer chain is in commissioning phase. In the future the exchange of photocathodes between the laboratories offers the possibility to test different types of photocathodes in different SRF-photoinjectors.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB029  
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TUPAB031 Status and Perspectives of the S-DALINAC Polarized-Electron Injector electron, gun, experiment, laser 1388
 
  • M. Herbert, J. Enders, M. Espig, Y. Fritzsche, N. Kurichiyanil, M. Wagner
    TU Darmstadt, Darmstadt, Germany
  
  Funding: Work supported by the Deutsche Forschungsgemeinschaft through grants GRK 2128 and SFB 1245
The S-DALINAC Polarized Injector (SPIn) uses GaAs photocathodes to provide pulsed and/or polarized electron beams for nuclear-structure investigations. Recently, a test facility for Photo-Cathode Activation, Test and Cleaning using atomic-Hydrogen \mbox{(Photo-CATCH)} has been developed. This setup uses an inverted-insulator geometry for the photo-electron gun. Currently, tests and optimizations are conducted at \mbox{Photo-CATCH} in order to implement this new gun design at SPIn. We will present the current status of \mbox{Photo-CATCH}, the planned upgrade of SPIn (aimed at an operational voltage of 200 kV) and future measurements. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB031  
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TUPAB032 Development of a Cryogenic GaAs DC Photo-Gun for High-Current Applications electron, cryogenics, vacuum, ion 1391
 
  • S. Weih, T. Eggert, J. Enders, M. Espig, Y. Fritzsche, N. Kurichiyanil, M. Wagner
    TU Darmstadt, Darmstadt, Germany
  
  Funding: Work supported by DFG (GRK 2128) and BMBF (05H15RDRB1)
For high-current applications of GaAs photocathodes it is necessary to maximize the charge lifetime of the cathode material to ensure reliable operation. By means of cryogenic cooling of the electrode, the local vacuum conditions around the source can be improved due to cryogenic adsorption of reactive rest-gas molecules at the surrounding walls. Furthermore, the cooling also allows a higher laser power deposited in the material, resulting in higher currents that can be extracted from the cathode. Ion-backbombardment is expected to be reduced using electrostatic bending of the electrons behind the cathode. To measure the characteristics of such an electron source, a dedicated set-up is being developed at the Photo-CATCH test facility in Darmstadt. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB032  
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TUPAB050 A Lifetime Study of CsK2Sb Multi-Alkali Cathode laser, vacuum, electron, experiment 1440
 
  • M. Kuriki, L. Guo, M. Urano, A. Yokota
    HU/AdSM, Higashi-Hiroshima, Japan
  • K. Negishi
    Iwate University, Morioka, Iwate, Japan
  • Y. Seimiya
    KEK, Ibaraki, Japan
  
  Funding: Quantum beam project by the Ministry of Education, Culture, Sports, Science, and Technology, entitled High Brightness Photon Beam by Laser Compton Scattering and Cooperative supporting Program for Research Education in University by KEK(High Energy Accelerator Research Organization)
\rm CsK2Sb is a high performance photo-cathode for accelerators requiring the high brightness electron beam. It can be driven by a green laser generated as SHG of a solid state laser. The quantum efficiency is as high as 10\%. In this article, the robustness of the cathode was studied experimentally. We found that 1/e lifetime of the cathode was inversely proportional to the vacuum pressure. The normalized temporal life was \rm (4.72± 0.08)× 10-5~Pa.hour for 532 nm laser. The lifetime regarding to the extracted charge density was also inversely proportional to the vacuum pressure. The normalized charge life was \rm (1.19± 0.03± 0.04)× 10-4 Pa.C/mm2. The cathode is robust enough for a high brightness electron accelerator. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB050  
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TUPAB051 Substrate Dependence of CsK2Sb Cathode Performance electron, laser, experiment, lattice 1443
 
  • M. Kuriki, L. Guo, M. Urano, A. Yokota
    HU/AdSM, Higashi-Hiroshima, Japan
  • K. Negishi
    Iwate University, Morioka, Iwate, Japan
  • Y. Seimiya
    KEK, Ibaraki, Japan
  
  Funding: Quantum beam project by the Ministry of Education, Culture, Sports, Science, and Technology, entitled High Brightness Photon Beam by Laser Compton Scattering and Cooperative supporting Program for Research and education in University by KEK(High Energy Accelerator Research Organization).
\rm CsK2Sb is a high performance cathode which can be driven with a green laser. The cathode is generated by evaporation on a substrate in a high vacuum environment. The cathode was evaporated on various material and surface condition to evaluate the dependence of the cathode performance. GaAs (100), Si(100), and Si(111) were examined as samples of the substrate. For each materials, the cathode on the cleaned and as-received substrates were examined and those on the cleaned showed better performance than the as-received for all materials. The detail of the experimental results are presented. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB051  
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TUPAB059 Study on CsKSb Photocathode for the RF Electron Gun gun, electron, cavity, laser 1456
 
  • H. Ono, J. Miyamatsu, M. Washio
    Waseda University, Tokyo, Japan
  • H. Iijima
    Tokyo University of Science, Tokyo, Japan
  • K. Sakaue
    Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
  
  At Waseda University, we have been developing a Cs-Te photocathode S-band RF electron gun and application experiments of the electron beam. On the experiments, charge amount is important factor, which strongly depends on laser power and photocathode quality. At present, we are studying CsKSb photocathode to increase the charge amount of an electron beam generated from the RF-Gun. As a result of using CsKSb photocathode in the RF-cavity, we obtained as much charge as using Cs-Te photocathode but the lifetime was shorter than that of Cs-Te. In order to lengthen the photocathode lifetime, we tried to coat a protective film on CsKSb photocathode surface and investigated its robustness for poor vacuum condition that simulates cathode transportation and usage in the RF-Gun. In this conference, we report current status of fabricating coated photocathode and future prospects.
A. Buzulutskov et al. The protection of K-Cs-Sb photocathodes with CsBr films Nuclear Instruments and Methods in Physics Research A 400 (1997) 173-176 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB059  
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TUPAB074 Measurements of Thermal Emittance for Cesium Telluride Photocathodes in an L-Band RF Gun laser, emittance, gun, electron 1491
 
  • L.M. Zheng, W. Gai, C.-X. Tang
    TUB, Beijing, People's Republic of China
  • W. Gai, C.-J. Jing, W. Liu, N.R. Neveu, J.G. Power, J.H. Shao, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
  • W. Liu
    Euclid TechLabs, LLC, Solon, Ohio, USA
  
  The thermal emittance is a major contributor to the final emittance of an electron beam in a photocathode RF gun. In this paper we present measurement results of thermal emittance for the cesium telluride photocathode at the Argonne Wakefield Accelerator (AWA) facility using the quadrupole scan method. Measurements of the thermal emittance vs. the laser spot size are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB074  
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TUPAB076 Design of an X-Band Photocathode for Tsinghua Thomson Scattering X-Ray Source gun, laser, solenoid, emittance 1497
 
  • L.Y. Zhou, H.B. Chen, Y.-C. Du, W. Gai, W.-H. Huang, J. Shi, C.-X. Tang, D. Wang, Z. Zhang, Z. Zhou
    TUB, Beijing, People's Republic of China
  
  Compared with S-band and C-band accelerating structures, X-band structures can run at a higher accelerating gradient and are more compact in size. In order to obtain higher electron energy in a limited space, a new X-band photo-injector operating at 11.424GHz has been designed at the Accelerator Laboratory of Tsinghua University. The structural design of the X-band photo-cathode RF gun and the accelerating structures as well as the beam dynamics simulation are presented in this paper, followed by the optimization of the structure based on the dispersed optimization experiment method(DOE). The results show that the design satisfies the working requirements with a small space occupied and a high beam quality.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB076  
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TUPAB083 Commissioning Experience and Beam Optimization for DCLS Linac linac, gun, emittance, FEL 1509
 
  • M. Zhang, D. Gu, Q. Gu, D. Huang, Z. Wang
    SINAP, Shanghai, People's Republic of China
  
  Dalian Coherent Light Source (DCLS), which will focus on the Physical Chemistry with time-resolved pump-probe experiments and EUV absorption spectroscopy techniques, is the first high gain FEL user facility in China. The 300MeV linac consists of a laser-driven rf-gun followed by 7 Sband accelerating tubes. A magnetic chicane is adopted to get the desired 300A peak current. After 5 months component installation, first photoelectrons were generated on 17 August 2016. In this paper, we give a summary of the commissioning experience and the beam parameters measurements. In addition, beam jitter sources are studied based on real machine performances.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB083  
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TUPAB095 The New MAX IV Gun Test Stand gun, laser, emittance, operation 1537
 
  • J. Andersson, F. Curbis, M. Kotur, D. Kumbaro, F. Lindau, E. Mansten, S. Thorin, S. Werin
    MAX IV Laboratory, Lund University, Lund, Sweden
  
  The gun test stand from MAX-Lab has been upgraded and moved to a new facility at the MAX IV Laboratory. The new test stand will reuse parts of the equipment from the old test stand but a number of improvements to the setup are be made. In this paper we report on the design of the new gun test stand, research plans in the near future as well as planned and possible future research topics.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB095  
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TUPAB096 Pulse Shaping at the MAX IV Photoelectron Gun Laser laser, gun, electron, emittance 1541
 
  • M. Kotur, J. Andersson, M. Brandin, F. Curbis, L. Isaksson, D. Kumbaro, F. Lindau, E. Mansten, D. Olsson, R. Svärd, S. Thorin, S. Werin
    MAX IV Laboratory, Lund University, Lund, Sweden
  • J. Björklund Svensson
    Lund University, Lund, Sweden
  
  A motivation for the development of a versatile, programmable source of shaped picosecond pulses for use in photocathode electron gun preinjectors is presented. We present the experimental setup for arbitrary longitudinal pusle shaping of the MAX IV photocathode gun laser. The setup consists of a grating-based Fourier-domain shaper capable of stretching the pulses directly in the UV domain. Preliminary results are presented and discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB096  
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TUPAB097 MAXIV Photocathode Gun Laser System Specification and Diagnostics laser, gun, linac, diagnostics 1544
 
  • F. Lindau, J. Andersson, J. Björklund Svensson, M. Brandin, F. Curbis, L. Isaksson, M. Kotur, D. Kumbaro, E. Mansten, D. Olsson, R. Svärd, S. Thorin, S. Werin
    MAX IV Laboratory, Lund University, Lund, Sweden
  • J. Björklund Svensson
    Lund University, Division of Atomic Physics, Lund, Sweden
  
  The MAXIV injector has two guns - a thermionic used for ring injections, and a photocathode used for short pulse facility operation. A commercial Ti:sapphire laser from KMLabs drives the copper based photocathode gun. It has been running without major issues for more than 3 years. The laser delivers up to §I{500}{\textmu J} on the cathode at the third harmonic, §I{263}{nm}, via a vacuum laser transport system. To achieve the desired pulse duration of 2–§I10{ps} the laser pulses, originally ~§I{100}{fs} long, are stretched with a prism pair and the resulting §I{1.5}{ps} pulses stacked by a series of birefringent \textalpha -BBO crystals. Diagnostics consist of photodiodes, spectrometers, and cameras. Longitudinal pulse characterization is done with a cross correlator and a UV FROG.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB097  
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TUPAB102 Compact Electron RF Travelling Wave Gun Photo Injector gun, laser, solenoid, electron 1550
 
  • R. Zennaro, P. Craievich, C.P. Hauri, L. Stingelin, A. Trisorio, C. Vicario
    PSI, Villigen PSI, Switzerland
  
  This paper reports on studies of a travelling wave photo gun as multipurpose device. The gun would be a cheap and compact alternative to thermionic guns with a bunching system or a standing wave photo injector gun. It allows one to reach much larger beam energies at the gun output. It can provide a beam with energy of up to 50 MeV and several hundred pC charge with low emittance and short bunch length. The laser system is a compact, industrial grade system with high MTBF and low maintenance cost. The gun design is based on the two-meter accelerating structures installed in SwissFEL, only the input coupler has been modified to accommodate the cathode. The gun is powered by a C-band (5.712 GHz) modulator-klystron system, identical to those of SwissFEL. The input coupler is a simple double feed coupler and it has been designed to increase the electric field enhancement at the cathode surface to improve the emittance. The first three accelerating cells have been readjusted in length in order to get the proper phase advance and synchronism with the beam. The remaining 110 accelerating cells and the output coupler follows the original design of the accelerating cavities for SwissFEL.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB102  
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TUPAB126 Multi-objective Genetic Optimization of Single Shot Ultrafast Electron Diffraction Beamlines gun, emittance, electron, cavity 1615
 
  • C.M. Gulliford, A.C. Bartnik, I.V. Bazarov
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • J.M. Maxson
    UCLA, Los Angeles, California, USA
  
  We present the results of multi-objective genetic algorithm optimizations of two single-shot ultrafast electron diffraction (UED) beam lines. The first is based on a 225 kV dc gun featuring a novel cryocooled photocathode system and buncher cavity. The second uses a 100 MV/m 1.6 cell normal conducting rf (NCRF) gun, as well as a 9 cell 2 Pi/3 bunching cavity placed between two solenoids. Optimizations of the transverse projected emittance as a function of bunch charge are presented and discussed in terms of the scaling laws derived in the charge saturation limit. Additionally, optimization of the transverse coherence length as a function of final rms bunch length at the sample location have been performed. These results demonstrate the viability of the approaches taken for both beamlines studied as well as the use of using genetic algorithms in the design and operation of UED beamlines.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB126  
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TUPAB127 A Cryogenically Cooled High Voltage DC Photogun gun, electron, cryogenics, vacuum 1618
 
  • H. Lee, I.V. Bazarov, L. Cultrera
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  A DC high voltage photogun with cryogenically cooling of the electrode has been newly built at Cornell University. This gun is designed to provide a DC high voltage and a photocathode in this gun can be cooled down to a cryogenic temperature. A photocathode puck design from INFN/DESY/LBNL is used, so we will be able to run a photocathode from other institutions as well. This paper describes the mechanical, thermal, and high voltage design of this gun. We also present data of high voltage conditioning and the thermal profile along the electrode structure.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB127  
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TUPAB128 Single Photoemitter Tips in a DC Gun: Limiting Aberration-induced Emittance emittance, electron, laser, cryogenics 1622
 
  • I.V. Bazarov, L. Cultrera, C.M. Gulliford, H. Lee
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • H.K. Fung
    Cornell University, Ithaca, New York, USA
  • J.M. Maxson
    UCLA, Los Angeles, California, USA
  
  Ultrafast electron diffraction (UED) offers unique advantages over x-ray diffraction, like stronger scattering cross-section, versatility in sample types and ability to offer smaller apparatus foot print. There is a growing need to increase brightness of electron beams especially for single-shot UED applications. We explore the utilization of field enhancement from a micron-scale single tip inside a DC gun to obtain brighter sub-pC electron beams using a nominal cathode electric field of several MV/m. The additional field enhancement can place moderate voltage sources on par with the highest gradient devices and allow improved performance presently not possible in the existing photoemission guns.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB128  
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TUPAB129 Optimization of Beam Dynamics for an S-Band Ultra-High Gradient Photoinjector brightness, gun, electron, emittance 1626
 
  • A.D. Cahill, A. Fukasawa, J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
  • C. Limborg, W. Qin
    SLAC, Menlo Park, California, USA
  
  Funding: Work Supported by DOE/SU Contract DE-AC02-76-SF00515, US NSF Award PHY-1549132, the Center for Bright Beams, and DOE SCGSR Fellowship. Travel to IPAC'17 supported by the Div. of Phys. of the US NSF (Accel. Sci. Prog.) and the Div. of Beam Phys. of the APS
New electron sources with improved brightness are desired to enhance the capabilities of FELs, making them more compact and fully coherent. Improvements in electron source brightness can be achieved by increasing electric fields on the cathode of photo-emitted electron guns. Recent developments in pulsed RF accelerator structures show that very high gradient fields can be sustained with low breakdown rates by operating at cryo-temperatures, which when applied to photoguns will lead to a large increase in the electron beam brightness. In particular, our simulations show that when operating with a peak gradient field of 240 MV/m on the cathode of an S-band, electron beam brightness of 80~nC/(mm· mrad)2/mm can be achieved with 100~pC bunches. In this paper, we present the design and optimization of an 1.x cell S-Band RF photoinjector, where the x varies from 4-6. The optimization in brightness has been obtained by using a multi-objective genetic algorithm on the solutions calculated with the ASTRA code. We calculate the optimum length of the rf gun, position of accelerating structure, and laser pulse dimensions for a variety of charges. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB129  
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TUPAB139 Design of an X-Band Photoinjector Operating at 1 kHz gun, solenoid, cavity, power-supply 1659
 
  • W.S. Graves, A.C. Goodrich, M.R. Holl, N.J. O'Brien
    Arizona State University, Tempe, USA
  • V. Bharadwaj, P. Borchard
    Tibaray Inc., Stanford, USA
  • V.A. Dolgashev, E.A. Nanni
    SLAC, Menlo Park, California, USA
  
  A kHz repetition rate RF photoinjector with novel features has been designed for the ASU CXLS project. The photoinjector consists of a 9.3 GHz 4.5 cell standing-wave RF cavity that is constructed from 2 halves. The halves are brazed together, with the braze joint bisecting the irises and cells, greatly simplifying its construction. The cathode is brazed onto this assembly. RF power is coupled into the cavity through inline circular waveguide using a demountable TM01 mode launcher. The mode launcher feeds the power through 4 ports distributed azimuthally to eliminate both dipole and quadrupole field distortions. The brazed-in cathode and absence of complex power coupler result in a very inexpensive yet high performance device. The clean design allows the RF cavity to sit entirely within the solenoid assembly. The cathode gradient is 120 MV/m at 3 MW of input power. The cathode cell is just 0.17 RF wavelength so that laser arrival phase for peak acceleration is 70 degrees from zero crossing resulting in exit energy of 4 MeV. The photoinjector will operate with 1μs pulses at 1 kHz, dissipating 3 kW of heat. Details of the design are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB139  
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TUPAB142 Tracking of Electrons Created at Wrong RF Phases in the RHIC Low Energy Cooler electron, space-charge, cavity, laser 1666
 
  • J. Kewisch, A.V. Fedotov, D. Kayran, S. Seletskiy
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by the US Department of Energy under contract No. DE-SC0012704.
The RHIC Low Energy Cooler will be based on a 400 keV DC electron gun with a photo-cathode and a 2.2 MeV SRF booster cavity. Electron that leave the cathode at the wrong time may be decelerated and turned around in the booster and return to the cathode with energies up to 1 MeV. On the way back these electron will encounter the defocussing EM fields up to nine following electron bunches. Such electrons may be created for various reasons: Cosmic rays, stray laser light including a catastrophic failure of the laser timing system or as secondaries of returning electrons. We present tracking results from the GPT program* and discuss the consequences for the machine protection system.
* www.pulsar.nl 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB142  
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TUPIK030 Characterization of the AMIT Internal Ion Source With a Devoted DC Extraction Test Bench ion, ion-source, electron, cyclotron 1740
 
  • D. Obradors-Campos, M.B. Ahedo, J.M. Barcala, J. Calero, P. Calvo, M.A. Domínguez, E.F. Estévez, J.M. Figarola, L. García-Tabarés, D. Gavela, P. Gómez, A. Guirao, J.L. Gutiérrez, J.I. Lagares, D. López, L.M. Martínez, J. Munilla, C. Oliver, J.M. Pérez Morales, I. Podadera, E. Rodríguez García, F. Toral, R. Varela, C. Vázquez
    CIEMAT, Madrid, Spain
  • R. Iturbe, B. López
    ANTEC Magnets SLU, Vizcaya, Spain
  
  Funding: Work partially funded under the Resolution of the Spanish Ministery of Economy, Industry and Competitiveness dated May 24 th, 2016 and project FIS2013-40860-R
With the main aim of a compact machine for 18F and 11C radioisotope production, AMIT cyclotron relies on a superconducting 4T magnet with an internal cold cathode PIG ion source for H− production. Given the limited access to the ion source in the cyclotron as well the reduced number of beam diagnostics, an experimental facility was proposed for the commissioning of such ion source. The versatility of this test bench, which includes a movable puller, gives us the opportunity to validate and characterize the ion source behavior as well as to optimize the H− production. In a first stage, the discharge characteristics of the ion source has been studied in the CIEMAT IST facilities. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK030  
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TUPIK051 Statistics on High Average Power Operation and Results from the Electron Beam Characterization at PITZ gun, operation, vacuum, Windows 1806
 
  • Y. Renier, P. Boonpornprasert, J.D. Good, M. Groß, H. Huck, I.I. Isaev, D.K. Kalantaryan, M. Krasilnikov, X. Li, O. Lishilin, G. Loisch, D. Melkumyan, A. Oppelt, H.J. Qian, T. Rublack, C. Saisa-ard, F. Stephan, Q.T. Zhao
    DESY Zeuthen, Zeuthen, Germany
  • G. Asova
    INRNE, Sofia, Bulgaria
  • M. Bousonville, S. Choroba, S. Lederer
    DESY, Hamburg, Germany
  
  The Photo Injector Test Facility at DESY in Zeuthen (PITZ) develops, tests and characterizes high brightness electron sources for FLASH and European XFEL. Since these FELs work with superconducting accelerators in pulsed mode, also the corresponding normal-conducting RF gun has to operate with long RF pulses. Generating high beam quality from the photo-cathode RF gun in addition requires a high accelerating gradient at the cathode. Therefore, the RF gun has to ensure stable and reliable operation at high average RF power, e.g. 6.5 MW peak power in the gun for 650 μs RF pulse length and 10 Hz repetition rate for the European XFEL. Several RF gun setups have been operated towards these goals over the last years. The latest gun setup is in operation since March 2016 and includes RF Gun 4.6 with an improved contact spring design. The RF input distribution consists of a coaxial coupler, a T-combiner and 2 RF windows from DESY production. In this contribution we will present statistics on the high average power operation and results from the characterization of the produced electron beam.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK051  
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TUPVA115 Progress with Long-Range Beam-Beam Compensation Studies for High Luminosity LHC electron, simulation, proton, optics 2358
 
  • A. Rossi, O. Aberle, J. Albertone, A. Bertarelli, C.B. Boccard, F. Carra, G. Cattenoz, Y. Delaup, S.D. Fartoukh, G. Gobbi, J. Lendaro, Y. Papaphilippou, D. Perini, S. Redaelli, H. Schmickler, C. Zanoni
    CERN, Geneva, Switzerland
  • A.M. Barnyakov, A.E. Levichev, D.A. Nikiforov
    BINP SB RAS, Novosibirsk, Russia
  • M. Fitterer, A.S. Patapenka, G. Stancari, A. Valishev
    Fermilab, Batavia, Illinois, USA
  
  Long-range beam-beam (LRBB) interactions can be a source of emittance growth and beam losses in the LHC during physics and will become even more relevant with the smaller '* and higher bunch intensities foreseen for the High Luminosity LHC upgrade (HL-LHC), in particular if operated without crab cavities. Both beam losses and emittance growth could be mitigated by compensat-ing the non-linear LRBB kick with a correctly placed current carrying wire. Such a compensation scheme is currently being studied in the LHC through a demonstration test using current-bearing wires embedded into col-limator jaws, installed either side of the high luminosity interaction regions. For HL-LHC two options are considered, a current-bearing wire as for the demonstrator, or electron lenses, as the ideal distance between the particle beam and compensating current may be too small to allow the use of solid materials. This paper reports on the ongoing activities for both options, covering the progress of the wire-in-jaw collimators, the foreseen LRBB experiments at the LHC, and first considerations for the design of the electron lenses to ultimately replace material wires for HL-LHC.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA115  
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WEPAB024 Commissioning and First Heating with the European XFEL Laser Heater laser, undulator, electron, FEL 2625
 
  • M. Hamberg
    Uppsala University, Uppsala, Sweden
  • F. Brinker, M. Scholz
    DESY, Hamburg, Germany
  
  Funding: We thank DESY and Swedish research council under Project number DNR-828-2008-1093 for financial support.
The Laser Heater of the European XFEL has been installed and commissioning is in progress. We discuss the setup and the results of the first electron beam heating in the injector section. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB024  
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WEPAB116 LCLS Injector Laser Shaping and Applications laser, electron, FEL, emittance 2844
 
  • S. Li, S.C. Alverson, D.K. Bohler, A.B. Egger, A.R. Fry, S. Gilevich, Z. Huang, A. Miahnahri, D.F. Ratner, J. Robinson, F. Zhou
    SLAC, Menlo Park, California, USA
  
  In the Linear Coherent Light Source (LCLS) at SLAC, the injector laser plays an important role as the source of the electron beam for the Free Electron Laser (FEL). The beam emittance and FEL performance are highly related to the transverse shape of the injector laser. When the injector laser has hot spots and non-uniformities that can carry over to the electron beam and degrade electron emittance and FEL performance, it requires long hours of manual adjustment by laser engineers and strenuous machine tuneup. The injector laser shaping project at LCLS aims to have precise control of the driver laser transverse profile in order to produce arbitrary electron beam profiles, which will enable us to study effects of laser shape on beam emittance and FEL performances. We use a digital micromirror device (DMD) to manipulate the drive laser profile. In this paper, we briefly discuss the implementations of laser shaping at LCLS. We demonstrate two applications of laser shaping. We present results of using laser shaping to control the X-ray laser output via an online optimizer. We also show the photocathode quantum efficiency measurements across cathode surface using the DMD.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB116  
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WEPIK025 Spectral Diagnostics of Argon Plasma in a 10mm Aperture Plasma Window plasma, electron, vacuum, ion 2978
 
  • P.P. Gan, S. Huang, Y.R. Lu, S.Z. Wang, Z.X. Yuan, K. Zhu
    PKU, Beijing, People's Republic of China
  
  A 10 mm diameter 60 mm long plasma window has been designed and managed to generate arc discharge with argon gas experimentally in Peking University. Based on the previous experiments and simulations, we have measured the electron temperature and density of the plasma via argon spectral diagnostics, and analyzed the conditions to satisfy the criterion of local thermal equilibrium (L.T.E). The electron temperature is in the range of 12000 K to 16000 K. The electron density is in the range of 2.2×1016 cm-3 to 3.2×1016 cm-3, increasing with discharge current and gas flow rate. The results indicate that our argon plasma is in the L.T.E status. The sealing pressure characteristics of the plasma window is mentioned as well.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK025  
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WEPVA117 Preliminary Mechanical Design Study of the Hollow Electron Lens for HL-LHC electron, solenoid, proton, gun 3547
 
  • C. Zanoni, G. Gobbi, D. Perini
    CERN, Geneva, Switzerland
  • G. Stancari
    Fermilab, Batavia, Illinois, USA
  
  A Hollow Electron Lens has been proposed in order to improve performance of halo control and collimation in the Large Hadron Collider in view of its High Luminosity upgrade (HL-LHC). The concept is based on a beam of electrons that travels around the protons for a few meters. The electron beam is produced by a cathode and then guided by a strong magnetic field generated by a set of solenoids. Mechanical design and integration require a preliminary knowledge of the optimal configuration of the solenoids that drive the electron trajectories. The estimation of such trajectories by means of a dedicated Matlab tool is presented. The influence of the main geometrical and electrical parameters is analysed and discussed. The main mechanical design choices are also outlined along with the concept of the electron collector. The aim of this paper is to provide an overview of the feasibility study of the Electron Lens for LHC. The methods used in this study also serve as examples for future mechanical and integration designs of similar devices.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA117  
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THOBB1 High Power Test Results of the Eli-NP S-Band Gun Fabricated with the New Clamping Technology Without Brazing gun, vacuum, operation, klystron 3662
 
  • D. Alesini, A. Battisti, M. Bellaveglia, A. Falone, A. Gallo, V.L. Lollo, L. Pellegrino, S. Pioli, S. Tomassini, A. Variola
    INFN/LNF, Frascati (Roma), Italy
  • F. Cardelli, L. Palumbo
    University of Rome La Sapienza, Rome, Italy
  • L. Ficcadenti, V. Pettinacci
    INFN-Roma, Roma, Italy
  • D.T. Palmer
    Istituto Nazionale di Fisica Nucleare, Milano, Italy
  • L. Piersanti
    INFN-Roma1, Rome, Italy
  
  High gradient RF photoguns have been a key development to enable several applications of high quality electron beams. They allow the generation of beams with very high peak current and low transverse emittance, satisfying the tight demands for free-electron lasers, energy recovery Linacs, Compton/Thomson Sources and high-energy linear colliders. A new fabrication technique for this type of structures has been recently developed and implemented at the Laboratories of the National Institute of Nuclear physics in Frascati (LNF-INFN, Italy). It is based on the use of special RF-vacuum gaskets that allow avoiding brazing in the realization process. The S-band gun of the Compton-based ELI-NP gamma beam system (GBS) has been fabricated with this new technique. It operates at 100 Hz with 120 MV/m cathode peak field and long RF pulses to allow the 32 bunch generation foreseen for the GBS. High gradient tests have been performed at full power full repetition rate and have shown the extremely good performances of the structure in term of breakdown rates. In the paper we report and discuss all experimental results with details of the electromagnetic design and mechanical realization processes.  
slides icon Slides THOBB1 [6.211 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THOBB1  
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THPAB023 The Influence of Initial Current Density Distribution on the Emittance Reduction emittance, gun, electron, flattop 3744
 
  • H. Yamashita, T. Kii, K. Masuda, K. Nagasaki, T. Nogi, H. Ohgaki, K. Torgasin, H. Zen
    Kyoto University, Kyoto, Japan
  
  In this study, the influence of current density distribu-tion on the cathode surface on the beam emittance evolution was investigated. The emittance evolution with different beam profiles (flat-top, peak and hollow distribution) have been compared. The modification of the current profile was shown to affect the axial distance of the point of minimal emittance over wide range. The hollow profile allows extending the axial distance of the point of emittance minimum keeping its value extremely low. Further the parameters of a peak profile, which give the smallest emittance were determined. This work demonstrates the significance of initial current density distribution for the emittance evolution.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB023  
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THPAB035 Central Region Design of the Hust SCC250 Superconducting Cyclotron cyclotron, ion-source, proton, injection 3778
 
  • L.X.F. Li
    Private Address, Wuhan, People's Republic of China
  • K.J. Kuanjun, M.Z. Mei, Z.J. Zeng, L.G. Zhang
    HUST, Wuhan, People's Republic of China
  
  Recently, the development of a 250 MeV cyclotron for advanced cancer therapy has been carried out by Huazhong University of Science and Technology(HUST) . It has four sector magnet and RF cavity which resonance frequency is 74.69 MHz. The internal ion source was adopted and the central region was designed to accommodate the starting beam. In this paper, the design of the central region to optimize the initial circumstances for H¬+ beam were described. The electric and magnetic field distribution were designed by electrostatic and magnetic solver in OPERA-3D TOSCA. The beam characteristics including the beam orbit, motion of the center of orbit, energy gain was investigated for central region was simulated by means of computer code Z3CYCLONE.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB035  
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THPAB073 Magnetized and Flat Beam Experiment at FAST emittance, electron, quadrupole, radiation 3876
 
  • A. Halavanau, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • J. Hyun
    Sokendai, Ibaraki, Japan
  • D. Mihalcea, P. Piot, T. Sen, J.C.T. Thangaraj
    Fermilab, Batavia, Illinois, USA
  
  A photocathode, immersed in solenoidal magnetic field, can produce canonical-angular-momentum (CAM) dominated electron beams. Such beams have an application in electron cooling of hadron beams and can also be uncoupled to yield asymmetric-emittance (flat) beams. In the present paper we explore the possibilities of the flat beam generation at Fermilab's Accelerator Science and Technology (FAST) facility linear accelerator. We present optimization of the beam flatness and four-dimensional transverse emittance and investigate the mapping and its limitations of the produced eigen-emittances to conventional emittances using a skew-quadrupole channel. Possible application of flat beams at the FAST facility are also discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB073  
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THPIK106 Low Power RF Characterisation of the 400 Hz Photoinjector for CLARA cavity, simulation, linac, vacuum 4342
 
  • L.S. Cowie, P. Goudket, B.L. Militsyn
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • G. Burt
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • T.J. Jones
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
  
  The CLARA High Repetition Rate Photoinjector comprises an S-band dual feed cavity and will operate at a repetition rate of up to 400 Hz and is capable of reaching an electric field strength on the cathode of 120 MV/m. The cavity was brazed after tuning and arrived at Daresbury Laboratory in February 2016. Extensive low power RF testing has been performed including measurements of the quality factors and coupling, pass-band mode frequencies, on axis field and RF repeatability of replacement of cathode plug. The dual feed coupler has been tuned and a Magic Tee type splitter installed. The photoinjector is now installed on the VELA beam line for commissioning and characterisation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK106  
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THPIK107 Design and Characterisation of the Focusing Solenoidal System for the CLARA High Repetition Rate Electron Source solenoid, multipole, simulation, alignment 4346
 
  • D.J. Scott, A.R. Bainbridge, K.B. Marinov, B.L. Militsyn, B.J.A. Shepherd
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • R.J. Cash, T.J. Jones
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
  • C.S. Edmonds
    The University of Liverpool, Liverpool, United Kingdom
  
  One of the critical components of electron injectors based on RF photoelectron sources is the focusing system. The system typically consists of a Main Focusing Solenoid and a Bucking Coil. Combination of these two solenoids should provide proper focusing of the beam at the exit of the RF cavity and zero longitudinal magnetic field in the photocathode plane to minimise the beam emittance. Imperfection of the solenoid design, manufacturing and alignment frequently leads to asymmetry of the focusing field which has to be compensated with additional coils. In order to eliminate mechanical and magnetic misalignment the CLARA photoinjector solenoids are mounted on one integrated bench and before installation into the beamline have been aligned in the magnet laboratory with simultaneous measurement of the magnetic field. In order to define multipole field components, dedicated measurements of the transverse magnetic field have been done. The amplitudes of the multipoles have been obtained from analysis of the transverse field map. We present here the results of field characterisation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK107  
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THPVA114 Status of High-Efficiency Klystron Development for the PLS-II and PAL-XFEL klystron, electron, cavity, gun 4726
 
  • S.J. Park, H.S. Han, W.H. Hwang, S.D. Jang, Y.D. Joo, K.R. Kim, C.D. Park, Y.J. Park
    PAL, Pohang, Kyungbuk, Republic of Korea
  • J.H. Hwang, S.S. Jang
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  • S.Y. Hyun, H.S. Seo, D.H. Yu
    Vitzrotech Co., Ltd., Ansan City, Kyunggi-Do, Republic of Korea
  
  Funding: This work was supported by the National R&D program (grant number: 2016R1A6B2A01016828) through the National Research Foundation of Korea (NRF).
We are developing a high-efficiency klystron for use in the PLS-II(Pohang Light Source II) and the PAL-XFEL in the Pohang Accelerator Laboratory. Since the PLS-II and the PAL-XFEL are already running with ~70 klystron modulator systems, newly developed klystrons should be designed to fit into existing installation spaces and power supplies, and their overall lengths(< 2 m) and beam perveances(2 upervs) should not be changed. In order to achieve the high efficiency with aforementioned boundary conditions, we are going to adopt a multi-cell output cavity in which, unlike those of the the SLAC X-band and KEK C-band klystrons, the cell frequencies are independently tuned to provide maximum beam-to-rf power conversion. In this article we report on our physics and engineering design efforts to achieve the high efficiency with minimum instabilities. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA114  
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THPVA148 Inexpensive Brazeless RF Accelerator gun, vacuum, operation, electron 4812
 
  • S.P. Antipov, C.-J. Jing, R.A. Kostin, S.V. Kuzikov, J.Q. Qiu
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • A.A. Vikharev
    IAP/RAS, Nizhny Novgorod, Russia
  
  Funding: DOE SBIR
A simple, inexpensive way to manufacture a standard radio frequency (RF) driven particle accelerator is presented. The simplification comes from two innovations: utilization of LCLS gun - type RF design to avoid an expensive brazing process and copper plating of stainless steel that further reduces manufacturing cost. This is realized by a special structure design where accelerating structure cells are made out of copper plated stainless steel with knife edges and structure irises - copper disks acts also as gaskets for vacuum and RF seal. Besides the reduced cost, brazeless assembly allows integration of effective cooling and magnet optics elements into accelerator cells. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA148  
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