Keyword: cathode
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MOZB01 Superconducting RF Guns: Emerging Technology for Future Accelerators gun, SRF, cavity, laser 4085
 
  • J. Teichert
    HZDR, Dresden, Germany
  
  This talk should give an overview of Superconducting photo injectors (SRF guns) and focus on the present status of SRF gun development, the technical requirements and the critical issues like cavity design, photocathode integration, and emittance compensation methods.  
slides icon Slides MOZB01 [22.198 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOZB01  
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MOZB02 Advances in Photocathodes for Accelerators electron, emittance, laser, experiment 48
 
  • L. Cultrera
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  This talk reviews advances in photocathode technology for accelerators: cathodes demonstrating record average currents and deliverable charge, possessing ultra-low intrinsic emittance and sub-picosecond response time. It addresses the grand challenge to combine all these useful properties into a single photoemitter - one that is being actively pursued by the research community.  
slides icon Slides MOZB02 [4.354 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOZB02  
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MOPME008 3d Full Electromagnetic Beam Dynamics Simulations of the Pitz Photoinjector simulation, laser, gun, emittance 391
 
  • Y. Chen, E. Gjonaj, W.F.O. Müller, T. Weiland
    TEMF, TU Darmstadt, Darmstadt, Germany
  
  Funding: work supported by DESY, Hamburg and Zeuthen sites
The electromagnetic (EM) simulation software CST STUDIO SUITE® * has been applied to investigate the beam dynamics for the electron gun of the Photo Injector Test facility at DESY, Zeuthen site (PITZ). A series of 3D beam dynamics simulations are performed to study the bunch injection process at PITZ with the objective of clarifying the discrepancies between measurements and simulations. Multiple comparisons are presented for the transverse emittance and the total emitted charge between the measurement data and simulation results using CST STUDIO SUITE®and Astra **.
* Computer Simulation Technology AG, website: http://www.cst.com/
** K. Floettmann‚ A Space Charge Tracking Algorithm, user manual (version 3), 2011 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPME008  
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MOPRI016 Hydrogen and Cesium Monitor for H− Magnetron Sources plasma, experiment, ion, controls 617
 
  • C.-Y. Tan, D.S. Bollinger, B.A. Schupbach, K. Seiya
    Fermilab, Batavia, Illinois, USA
  
  Funding: Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energ
The relative concentration of cesium to hydrogen in the plasma of a H− magnetron source is an important parameter for reliable operations. If there is too much cesium, the surfaces of the source become contaminated with it and sparking occurs. If there is too little cesium then the plasma cannot be sustained. In order to monitor these two elements, a spectrometer has been built and installed on a test and operating source that looks at the plasma. It is hypothesized that the concentration of each element in the plasma is proportional to the intensity of their spectral lines. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI016  
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MOPRI018 Influence of Growth Method on K3Sb Photocathode Structure and Performance synchrotron, experiment, scattering, emittance 624
 
  • S.G. Schubert, T. Kamps, M. Schmeißer
    HZB, Berlin, Germany
  • K. Attenkofer, J. Smedley
    BNL, Upton, Long Island, New York, USA
  • E.M. Muller
    SBU, Stony Brook, New York, USA
  • H.A. Padmore, J.J. Wong
    LBNL, Berkeley, California, USA
  • M. Ruiz-Osés
    Stony Brook University, Stony Brook, USA
  • J. Xie
    ANL, Argonne, Illinois, USA
  
  Funding: Supported by Director, OoS., OBES of US DOE, Contract DE-AC02-05CH11231, DE-AC02-98CH10886, KC0407-ALSJNTI0013, DE-SC0005713, germ. BMBF, Land Berlin, Helmholtz Assoc.. Use of CHESS by NSF, DMR-0936384.
Future high brightness photoelectron sources delivering >100 mA average current call for a new generation of photocathodes. Materials which qualify for this purpose should exhibit low intrinsic emittance, long lifetime and high quantum efficiency at photon energies in the visible range of the spectrum to relax drive laser requirements. A combination of material science techniques are used to determine the influence of the growth parameters on structure and performance of photocathode materials . In-situ XRR, XRD and GiSAXS measurements were performed at the synchrotron radiation sources, NSLS and CHESS. The growth of K3Sb, a precursor material of one of the prime candidates CsK2Sb, was studied intensively to optimize this intermediate growth step in terms of quantum efficiency and roughness. Three methods, a “layer by layer” type and a “super-lattice type” were examined. K3Sb exists in two crystallographic phases, namely cubic and hexagonal. The cubic phase exhibits a higher quantum efficiency at 532 nm than the hexagonal phase and transforms more easily into CsK2Sb, tuning this phase is believed to be one of the key parameters in the CsK2Sb growth. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI018  
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MOPRI019 In-situ Characterization of K2CsSb Photocathodes electron, laser, vacuum, ion 627
 
  • M. Schmeißer, A. Jankowiak, T. Kamps, S.G. Schubert
    HZB, Berlin, Germany
  • S.G. Schubert
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by German Bundesministerium für Bildung und Forschung contract 05K12CB2 PCHB and Land Berlin.
Alkali antimonide photocathodes with high quantum efficiency hold the promise of delivering electrons for high-brightness injectors. A drift type spectrometer (momentatron) was attached to the HZB preparation system to allow in-situ characterization within short time after fabrication and possibly identify correlations between growth process and cathode performance parameters. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI019  
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MOPRI020 Introducing GunLab – A Compact Test Facility for SRF Photoinjectors gun, electron, SRF, laser 630
 
  • J. Völker, R. Barday, A. Jankowiak, T. Kamps, J. Rudolph, S.G. Schubert, S. Wesch
    HZB, Berlin, Germany
  • A. Ferrarotto, T. Weis
    DELTA, Dortmund, Germany
  • V.I. Shvedunov
    MSU, Moscow, Russia
  • I.Yu. Vladimirov
    MSU SINP, Moscow, Russia
  
  Funding: Work supported by German Bundesministerium für Bildung und Forschung (BMBF contract 05K12CB2 PCHB and 05K10PEA), Land Berlin and grants of Helmholtz Association
Superconducting radio-frequency photoelectron injectors (SRF photoinjectors) are a promising electron source for high brightness accelerators with high average current and short pulse duration like FELs and ERLs. For the upcoming ERL project BERLinPro we want to test and commission different SRF photoinjectors and examine the beam performance of photocathode materials in an independent test facility. Therefore we designed GunLab to characterize the beam parameters from the SRF photoinjectors in a compact diagnostics beamline. In GunLab we want to investigate the complete 6 dimensional phase space as a function of drive laser and RF setup parameters. In this work we present the design and the estimated performance of GunLab. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI020  
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MOPRI021 Laser Systems Generating Short Polarized Electron Bunches at the S-DALINAC laser, electron, operation, experiment 633
 
  • M. Espig, J. Enders, Y. Fritzsche, A. Kaiser, M. Wagner
    TU Darmstadt, Darmstadt, Germany
  
  Funding: Supported by DFG within CRC634 and by the state of Hesse through the LOEWE center HIC for FAIR.
The source of polarized electrons at the superconducting Darmstadt electron linear accelerator S-DALINAC uses photo-emission from strained-layer superlattice-GaAs and bulk-GaAs photocathodes. This system is driven by either 3 GHz gain-switched diode lasers or a short-pulse Ti:Sapphire laser system. Highly polarized electrons are generated with laser light at 780 nm, while blue laser light is used for unpolarized high-current experiments. We present the existing pulsed laser systems and the planned developments for the diode laser system, including, e.g., impedance matching of the diode lasers, gain switching with short electrical pulses and pulsing with a Mach-Zehnder modulator. The pulsed operation is aimed at generating short electron bunches (< 50 ps) at the S-DALINAC with variable repetition rates from some MHz to 3 GHz. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI021  
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MOPRI024 NEA-GaAs (Cs, O) Photocathodes for the ELBE SRF Gun gun, vacuum, SRF, laser 639
 
  • R. Xiang, A. Arnold, P.N. Lu, P. Michel, P. Murcek, J. Teichert, H. Vennekate
    HZDR, Dresden, Germany
  
  Funding: supported by the European Community under the FP7 programme (EuCARD-2, contract number 312453, and LA3NET, contract number 289191), and by the BMBF grant 05K12CR1.
At HZDR a preparation chamber for NEA-GaAs (Cs, O) has been built and commissioned. GaAs is the next photocathode material for the ELBE SRF gun, which has been successfully operated with Cs2Te layer in last years. GaAs At HZDR a preparation chamber for NEA-GaAs (Cs, O) has been built and tested. GaAs is the next photocathode material for the ELBE SRF gun, which has been successfully operated with Cs2Te photocathode in last years. GaAs photocathodes are advantageous because of their high quantum efficiency (QE) with visible light and the extensive experiences of their use in DC guns. Furthermore, GaAs photocathodes provide the possibility to realize a polarized SRF gun in the future. In this presentation we will introduce the new preparation system and the first results of the GaAs tests. The new transfer system under construction will be also presented. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI024  
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MOPRI025 Recent Improvement of Cs2Te Photocathodes at HZDR gun, vacuum, SRF, cavity 642
 
  • R. Xiang, A. Arnold, P.N. Lu, P. Michel, P. Murcek, J. Teichert, H. Vennekate
    HZDR, Dresden, Germany
  
  Funding: Work supported by the European Community-Research Infrastructure Activity (EuCARD, contract number 227579), and the support of the German Federal Ministry of Education and Research grant 05 ES4BR1/8.
The SRF gun has been successfully operated for the radiation source ELBE at HZDR. To achieve higher current and lower beam emittance, a new niobium cavity with superconducting solenoid and a new 13 MHz laser have been recently developed. For this reason, better photocathodes with high quantum efficiency are urgently in demand. In this work we improve the present Cs2Te preparation system for cleaner environment and more precise stoichiometric control than before. A new mask is designed to prevent cesium pollution of the cathode body. Instead of Kapton only alumina ceramics are used for isolation, and the cathode plugs are degassed at higher temperature. New evaporators are installed and tested to obtain an accurate deposition rate. Furthermore, the cathode transfer system is thoroughly cleaned for a better vacuum condition. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI025  
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MOPRI026 Complete Simulation of Laser Induced Field Emission from Nanostructures Using a DGTD, PIC and FEM Code electron, laser, simulation, space-charge 645
 
  • A. Fallahi, F.X. Kärtner
    CFEL, Hamburg, Germany
  • K.K. Berggren, R. Hobbs, F.X. Kärtner, P.D. Keathley, M.E. Swanwick, L.F. Velasquez-Garcia, Y. Yang
    MIT, Cambridge, Massachusetts, USA
  
  Funding: DARPA contract number N66001-11-1-4192 and the Center for Free-Electron Laser Science, DESY Hamburg.
We present a general and efficient numerical algorithm for studying laser induced field emission from nanostructures. The method combines the Discontinuous Galerkin Time Domain (DGTD) method for solving the optical field profile, the Particle-In-Cell (PIC) method for capturing the electron dynamics and the Finite Element Method (FEM) for solving the static field distribution. The charge distribution is introduced to the time-domain method based on a modified Fowler-Nordheim field emission model, which accounts for the band-bending of the charge carriers at the emitter surface. This algorithm is capable of considering various effects in the emission process such as space-charge, Coulomb blockade and image charge. Simulation results are compared with experimental findings for optically driven electron emission from nanosharp Si-tips. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI026  
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MOPRI028 Different Countermeasures of Electron Amplification in the Photocathode Unit electron, SRF, gun, simulation 652
 
  • E.T. Tulu, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • A. Arnold
    HZDR, Dresden, Germany
  
  Funding: Federal Ministry for Research and Education BMBF; Project: 05K2013-HOPE
Superconducting radio frequency (SRF) structures may be subjected to electron multipacting (MP). The electrons emitted from one of the structure’s wall under certain conditions are accelerated by the RF field, thereby they may impact the wall again based on the field pattern in the structure. Accordingly the number of electrons increases exponentially caused by secondary electron emission*. The latter depends on the secondary emission coefficient of the surface material and the electron trajectory in the device under study**. This phenomenon limits the accelerating gradient in the cavity, moreover, it might cause an impair of RF components and distortion of the RF signal. Therefore, there should be an efficient countermeasure to suppress MP in order to boost the performance of the SRF gun. In this paper, three techniques of suppression of MP from the vicinity of the cathode, such as DC-bias, geometric modification and the microstructure of the cathode's surface, in the Rossendorf SRF gun are presented. The simulation has been done using CST Microwave Studio® and CST Particle Studio®***. Eventually, the efficient suppression method would be chosen for this particular case.
* H.Padamsee, J. Knobloch and T. Hays, 1998, Ch. 10.
** E. T. Tulu, A. Arnold and U. van Rienen, 16th International Conference on SRF, Paris, France, 2013.
*** CST AG, http://www.cst.com.
 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI028  
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MOPRI029 Spectrometer for Laser-pulsed Electrons from Field Emission Cathodes electron, laser, detector, controls 655
 
  • S. Mingels, B. Bornmann, D. Lützenkirchen-Hecht, G. Müller, V. Porshyn
    Bergische Universität Wuppertal, Wuppertal, Germany
  
  Funding: German Federal Ministry of Education and Research (BMBF). Project number: 05K13PX2.
In order to develop highly brilliant, pulsed electron sources based on photo-induced field emission (PFE), which combines advantages of photo and field emission (FE), a new measurement system was constructed at BUW*. In an UHV system the electrons are extracted from a cold cathode by a mesh electrode under pulsed laser illumination (3.5 ns, 10 Hz, 0.5 – 5.9 eV, > 0.3 mJ) and so far analyzed by a CW-spectrometer. Quantum efficiency investigations of flat metal (Au, Ag of different surface orientations) and semiconductor crystals (n- and p-Si**, GaN) yielded the expected work functions and revealed first hints for PFE effects. However, the kinetic energy of the electrons could not be measured with the CW-spectrometer. In addition, the achievable electric field (< 20 MV/m) was limited by parasitic FE. Hence, the system is presently upgraded with a spectrometer (resolution < 3 meV) that can handle electron pulses and a dust reduced environment is installed at the load lock. First results acquired with the upgraded apparatus on PFE cathodes will be presented at the conference.
* B. Bornmann et al., Rev. Sci. Instrum. 83, 013302 (2012).
** S. Mingels et al., Proc. FEL2013, New York, USA, p. 339. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI029  
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MOPRI031 Multi-alkali Photocathode R&D laser, electron, vacuum, experiment 661
 
  • Y. Seimiya, M. Kuriki, N. Yamamoto
    HU/AdSM, Higashi-Hiroshima, Japan
  
  Multi-alkali photocathode has excellent features: high quantum efficiency, long lifetime, and excitation by visible light, for example green laser. The multi-alkali cathode is considered to be one of the best candidate of the high brightness electron source of the advanced electron accelerator such as ERL and FEL. We study conditions of multi-alkali evaporations, such as thicknesses, substrate temperature, and evaporation rate, and examine the cathode performances, such as quantum efficiency and extractable current density. Antimony (Sb), potassium (K), and cesium (Cs) are used in our evaporation system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI031  
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MOPRI032 A STUDY ON ROBUSTNESS OF NEA-GAAS PHOTOCATHODE* electron, vacuum, experiment, emittance 664
 
  • K. Uchida, R. Kaku, M. Kuriki, K. Miyoshi, Y. Seimiya, N. Yamamoto
    HU/AdSM, Higashi-Hiroshima, Japan
  • H. Iijima
    Tokyo University of Science, Tokyo, Japan
  
  Electron source is one of the most important component in the advanced linac. There is a strong demand on the high performance cathode, such as small emittance, high brightness, and short pulse generation. NEA-GaAs photo-cathode is a unique technology which is capable for generating highly polarized and extremely low emittance beam. Quantum efficiency (QE) of the cathode is high in near IR region, so it is favor to generate a high current density beam. These advantages are originated to the Negative Electron Affinity (NEA) surface, but it is fragile so the operational lifetime is limited. A study on a robust NEA surface cathode is reported. According to the hetero-junction model, Cs-Te thin film deposited on GaAs forms a robust NEA surface. We performed the Cs-Te evaporation experiment on a clean GaAs cathode and measured QE spectra. We found that some sample showed a high quantum efficiency up to 900nm wavelength which strongly suggested a NEA surface formation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI032  
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MOPRI033 Quasi-traveling Wave Side Couple RF Gun Commissioning for SuperKEKB gun, cavity, emittance, coupling 667
 
  • T. Natsui, Y. Ogawa, M. Yoshida, X. Zhou
    KEK, Ibaraki, Japan
  
  We are developing a new RF gun for SuperKEKB. 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. New RF gun which has two side coupled standing wave field is developed. We call it quasi traveling wave side couple RF gun. This gun has a strong focusing field at the cathode and the acceleration field distribution also has a focusing effect. Beam commissioning has been started with the new RF gun. I will report the result of beam commissioning.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI033  
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MOPRI035 Development of the Photocathode LiTi2O4 and Evaluations of the Initial Emittance laser, electron, emittance, cavity 673
 
  • R. Inagaki, M. Hosaka, Y. Takashima, N. Yamamoto
    Nagoya University, Nagoya, Japan
  • T. Hitosugi, S. Shiraki
    Tohoku Uneversity, WPI-AIMR, Sendai, Japan
  • E. Kako, Y. Kobayashi, S. Yamaguchi
    KEK, Ibaraki, Japan
  • M. Katoh, T. Konomi, T. Tokushi
    UVSOR, Okazaki, Japan
  • Y. Okano
    IMS, Okazaki, Japan
  
  In UVSOR, the X-ray free electron laser (XFEL) based on linear accelerator with high pulse repetition about 1MHz has been designed as a candidate for the next radiation sources. We thought a combination of superconducting RF cavity and photocathode is an optimal electron gun for the new accelerator. For this electron gun, we propose a back-illuminated multi-alkali* photocathode with transparent superconductor LiTi2O4**. The reason for using LiTi2O4 is to reflect RF by using feature of penetration depth of superconductor, which is defined from London equation. This feature protects optical components from RF damage. However, LiTi2O4 is a new material and properties are not clear. We have measured the basic properties of this photocathode, such as magnetic susceptibility measurement and photoelectron spectrometry, etc. In this conference, we will explain the detail of the concept and advantage of this cathode, and show the result measured about the basic properties of this photocathode focusing on the initial emittance measurement.
* A. V. Lyashenko et al. JINST 4 P07005 (2009)
** Kumatani et al. APL 101 (2012) 123103″ 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI035  
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MOPRI037 Development of Iridium Cerium Photocathode for the Generation of High-Charge Electron Beam laser, electron, gun, linac 679
 
  • D. Satoh
    TIT, Tokyo, Japan
  • N. Hayashizaki
    RLNR, Tokyo, Japan
  • T. Natsui, M. Yoshida
    KEK, Ibaraki, Japan
  
  We developed an iridium cerium cathode material made by new production method for multi-purpose electron source. For multi-purpose electron source, we focused on the Ir5Ce compound which has a high melting point (> 2100 K) and a low work function (2.57 eV). This material has some excellent properties as both a thermionic cathode and a photocathode. For example, Ir5Ce thermionic cathode can generate one-order higher electrical current than a LaB6 cathode at the same temperature. Another advantage is that an Ir5Ce thermionic cathode has a lifetime two orders longer than that of a LaB6 thermionic cathode under the same conditions. Moreover, we discovered that this material has a reasonably high quantum efficiency (2.70 × 10−3 @213nm at 1000°C) and long-lifetime (> LaB6) as a photocathode. Our research shows that Ir5Ce compound is optimum material for a thermionic cathode and photocathode. We focused on this good emission properties under the high temperature and we tried to develop a backside electron beam heating system and demonstrate a laser pre-pulse heating for a high current thermionic gun system or high charge photocathode gun.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI037  
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MOPRI040 Design and Analysis of an Electron Beam in an Electron Gun for X-Ray Radiotherapy electron, gun, emittance, simulation 688
 
  • J.C. Lee, J.-S. Chai, M. Ghergherehchi, H.S. Kim, Y.S. Lee, S. Shin, Y.H. Yeon
    SKKU, Suwon, Republic of Korea
  • B.N. Lee
    KAERI, Dae-jeon, Republic of Korea
  
  Funding: This work was supported by (IT R&D program of MSIP/KEIT [10043897] and MOTIE [13-DU-EE-12]) in KOREA.
Electron linear accelerators are used as x-ray generators for diagnosing the human body. In this paper conceptual design of electron beam for compact electron gun was calculated by using EGN2w and CST-Particle Studio codes. The structure of the electron gun was used for Pierce and diode type and the specification of electron beam was selected as 500 cGy/min. Specifications of designed electron gun were focused on current, beam size and normalized emittance. Optimized beam current, diameter and normalized emittance are 226.88 mA, 0.689 mm (Full width) and 1.03π mm• mrad, respectively by using two simulation codes. Accuracy of simulation was verified by comparison of emitted beam current which has error of 0.74%.
* Subhash C. Sharma et al., Journal of applied clinical medical physics, 8, 3 (2007) 119-125.
* Yuichiro Kamino et al., Med. Phys. 34 (2007) 1797-1808.
 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI040  
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MOPRI041 Electrons Injectors with Cathode Diameter of 6/15mm and New Cup Energy Input on the Wave E11 for Accelerators electron, Windows, gun, target 692
 
  • K.G. Simonov, E.A. Alkhimenko, T.A. Batkova, S.I. Grishin, A.V. Mamontov, G.I. Pravdikovskaya, E.A. Stroykov
    ISTOK, Moscow Region, Russia
  • A.I. Shapovalov
    MRTI RAS, Moscow, Russia
  
  RPC "Istok" has created a number of electron injectors with voltage of 20-60kV and cathode diameter of 6-15mm of diode and triode designs. Injectors use the impregnated cathodes; the injector design allows rapid replacement of cathode assemblies. Injectors have been widely used in linear electron accelerators in Russia and Ukraine, in particular, in the sterilization accelerator center of JSC "MRTI RAS", Moscow, in the accelerator of the Russian Eye and Plastic Surgery Centre, Ufa. Have been proposed new input energy windows on the E11 wave, providing significant levels of transmission of the pulse power at high average power levels. Have been created two types of windows at 10-cm range, in which the ceramic disk made of ecologically clean alumina ceramic with diameter of 103mm and thickness of 13mm is used. In the first type of windows the heat transfer is provided from the peripheral portion, and in the second type of window – both from peripheral and central portions of the ceramic disk. These windows are used in accelerator of FSUE "NIIEFA" (St.Petersburg), installed at Izhora mill for testing the welding seals of atomic reactors and in accelerator of JSC "MRTI RAS".  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI041  
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MOPRI042 Recent Developments at the High-charge PHIN Photoinjector and the CERN Photoemission Laboratory laser, vacuum, feedback, operation 695
 
  • C. Heßler, E. Chevallay, S. Döbert, V. Fedosseev, I. Martini, M. Martyanov, A. Perillo Marcone, Sz. Sroka
    CERN, Geneva, Switzerland
  
  The high-charge PHIN photoinjector has originally been developed to study the feasibility of a photoinjector option for the drive beam of the CLIC Test Facility 3 (CTF3) at CERN and is now being used to investigate the feasibility of a drive beam photoinjector for CLIC. In this paper recent R&D efforts to improve the parameters of the existing system towards CLIC requirements will be discussed. This includes studies of a feedback loop for intensity stabilization, the upgrade of the PHIN vacuum system and the planned upgrade of the driving laser system. For photocathode production and R&D a dedicated photoemission laboratory is available at CERN. To increase the production rate of photocathodes and the availability of the photoemission lab for other studies, an upgrade of the photocathode preparation system with a load-lock system is under study and will also be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI042  
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MOPRI043 Study of a C-band Standing-wave Gun for the SwissFEL Injector gun, solenoid, coupling, emittance 698
 
  • M. Schaer, S. Bettoni, A. Citterio, P. Craievich, M. Negrazus, L. Stingelin, R. Zennaro
    PSI, Villigen PSI, Switzerland
  
  The baseline design of the SwissFEL injector foresees the "PSI Gun 1", a 2.6-cell RF photo-cathode gun operating at S-band frequency, as the electron source. In this paper a new design is presented where a 5.6-cell C-band gun could replace the PSI Gun 1 with no impact on the rest of the injector setup. A conservative maximum gradient of 135 MV/m at the cathode is assumed which drives the electron beam faster into the relativistic regime and therefore allows to tolerate larger charge densities. The presented solution also foresees a coaxial RF coupling from the cathode side in order to place the gun solenoid as near to the photo-cathode as possible, improving the emittance compensation. Astra simulations showed that the transverse beam brightness can be doubled before the first bunch compressor preserving the low transverse emittance value as compared to the current design for the S-band injector configuration of SwissFEL.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI043  
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MOPRI044 Feasibility Study of an Ultrafast Electron Diffraction System in NSRRC electron, gun, injection, emittance 701
 
  • P. Wang, K.C. Leou
    NTHU, Hsinchu, Taiwan
  • N.Y. Huang, W.K. Lau, A.P. Lee
    NSRRC, Hsinchu, Taiwan
  
  It has been suggested that the MeV beam generated from a laser-driven photo-cathode rf gun can be used for ultrafast electron diffraction (UED)*. The feasibility of operating the NSRRC photo-cathode rf gun system for ultrashort bunch generation is being investigated. The results of space-charge tracking calculations show that a low emittance, few hundred femtoseconds MeV beam with reasonable bunch charge can be generated for single shot UED experiments. In this report, a preliminary design of this UED system will be discussed.
* X.J. Wang et al., in Proceedings of PAC'03, p.420. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI044  
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MOPRI045 Beam Diagnostics E-GUN Test Stand at TARLA gun, electron, emittance, radiation 704
 
  • Ç. Kaya, A.A. Aksoy, A. Aydin, V. Karakilic, Ö. Karslı, E. Kazancı, B. Koc, S. Kuday, E.Ç. Polat, I. Sara, M. Yildiz
    Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey
  • S. Özkorucuklu
    Istanbul University, Istanbul, Turkey
  
  Funding: Work supported by Turkish State Planning Organization (Grant No: DPT2006K-120470)
Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) facility, which is essentially proposed to generate oscillator mode FEL in 3-250 microns wavelengths range, will consist of totally normal conducting injector system with 250 keV beam energy, two superconducting RF accelerating modules in order to accelerate the beam 15-40 MeV. Continuous wave (CW) electron beam will provided by TARLA thermionic electron gun (E-GUN). Various aspects of the Thermionic EGUN test stand to deliver the necessary electron beam in terms of bunch charge, current, energy, emittance and profile for the beam diagnostic will be discussed. Primarily measurements results of electron beam energy loss and transverse orbit will be shown as well as beam image and shape measurements.
On behalf of TARLA Collaboration 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI045  
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MOPRI046 The Evolution of the Transverse Energy Distribution of Electrons from a GaAs Photocathode as a Function of its Degradation State electron, detector, laser, brightness 707
 
  • L.B. Jones, B.L. Militsyn, T.C.Q. Noakes
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • H.E. Scheibler, A.S. Terekhov
    ISP, Novosibirsk, Russia
  
  The brightness of a photoelectron injector is fundamentally limited by the mean longitudinal and transverse energy distributions of the photoelectrons emitted from its photocathode, and the electron beam brightness is increased significantly if the mean values of these quantities are reduced. ASTeC have commissioned a Transverse Energy Spread Spectrometer (TESS – an experimental facility designed to measure these transverse and longitudinal energy distributions) which can be used for III-V semiconductor, alkali antimonide/telluride and metal photocathode research*. GaAs photocathodes were activated in our photocathode preparation facility (PPF)**, then transferred to TESS under XHV conditions and progressively degraded through controlled exposure to oxygen. We present commissioning data and initial measurements showing the evolution of the transverse energy distribution of electrons from GaAs photocathodes as a function of their degradation state.
* Proc. FEL ’13, TUPPS033, 290-293
** Proc. IPAC ’11, THPC129, 3185-3187 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI046  
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MOPRI051 Measurements of the Longitudinal Energy Distribution of Low Energy Electrons electron, laser, experiment, simulation 720
 
  • L.J. Devlin, O. Karamyshev, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • L.J. Devlin, O. Karamyshev, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • L.B. Jones, B.L. Militsyn, T.C.Q. Noakes
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  
  Funding: Work supported by STFC Cockcroft Core Grant No.ST/G008248/1
The Transverse Energy Spread Spectrometer (TESS) is an ASTeC experiment designed to measure the energy of electrons from different cathode materials. It is a dedicated test stand for future light sources. A full particle tracking code has been developed in the QUASAR Group, which simulates particle trajectories through TESS. Using this code it is possible to simulate different operational conditions of the experiment and cathode materials. The simulation results can then be benchmarked against experimental data to test the validity of the emission and beam transport model. Within this paper, results from simulation studies are presented and compared against experimental data as a collaboration within the Cockcroft Institute between ASTeC and the QUASAR Group for the case of measuring the longitudinal velocity distribution of electrons emitted from a gallium arsenide cathode using a grid structure as an energy filter. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI051  
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MOPRI054 Status of the APEX Project at LBNL gun, cavity, FEL, linac 727
 
  • F. Sannibale, K.M. Baptiste, C.W. Cork, J.N. Corlett, S. De Santis, L.R. Doolittle, J.A. Doyle, D. Filippetto, G.L. Harris, G. Huang, H. Huang, R. Huang, T.D. Kramasz, S. Kwiatkowski, R.E. Lellinger, V. Moroz, W.E. Norum, C. F. Papadopoulos, G.J. Portmann, H.J. Qian, J.W. Staples, M. Vinco, S.P. Virostek, R.P. Wells, M.S. Zolotorev
    LBNL, Berkeley, California, USA
  • R. Huang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  Funding: Work 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 (LBNL), consists in the development of an injector designed to demonstrate the capability of the VHF gun, a normal conducting 186 MHz RF gun operating in CW mode, to deliver the brightness required by X-ray FEL applications at MHz repetition rate. APEX is organized in 3 main phases where different aspects of the required performance are gradually demonstrated. The status and future plans for the project are presented. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI054  
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MOPRI055 APEX Present Experimental Results gun, electron, emittance, laser 730
 
  • D. Filippetto, C.W. Cork, S. De Santis, L.R. Doolittle, G. Huang, R. Huang, W.E. Norum, C. F. Papadopoulos, G.J. Portmann, H.J. Qian, F. Sannibale, J.W. Staples, R.P. Wells
    LBNL, Berkeley, California, USA
  • J. Yang
    TUB, Beijing, People's Republic of China
  
  Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231
The APEX electron source at LBNL combines high-repetition-rate and high beam brightness typical of photo-guns, delivering low emittance electron pulses at MHz frequency. Proving the high beam quality of the beam is an essential step for the success of the experiment. It would enable high repetition rate operations for brightness-hungry applications such as X-Ray FELs, and MHz ultrafast electron diffraction. A full 6D characterization of the beam phase space at the gun beam energy (750 keV) is foreseen in the first phase of the project. Diagnostics for low and high current measurements have been installed and tested, measuring the performances of different cathode materials in a RF environment with mA average current. A double-slit system allows the characterization of beam emittance at high charge and full current (mA). An rf deflecting cavity and a high precision spectrometer allow the characterization of the longitudinal phase space. Here we present the latest results at low and high repetition rate, discussing the tools and techniques used. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI055  
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MOPRI056 Design and Fabrication of a VHF - CW High Repetition Rate Electron Gun cavity, gun, vacuum, operation 733
 
  • R.P. Wells, B. Ghiorso, F. Sannibale, J.W. Staples
    LBNL, Berkeley, California, USA
  • T.M. Huang
    IHEP, Beijing, People's Republic of China
  
  Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231
A high repetition rate, MHz, electron source is a key element in future FEL based light sources. The Advance Photo-injector Experiment (APEX) at Lawrence Berkeley National Laboratory (LBNL) consists of a high repetition rate 186 MHz (VHF-band) CW electron gun, 1 MHz UV laser source and the diagnostic components necessary to quantify the gun’s performance. The gun design is based on well established, conventional RF cavity design, with a couple notable exceptions. The basis for the selection of this technology, novel design features, fabrication techniques and measured cavity performance are presented. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI056  
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MOPRI057 Photoemission from III-V Semiconductor Cathodes electron, vacuum, photon, scattering 736
 
  • S.S. Karkare
    Cornell University, Ithaca, New York, USA
  • I.V. Bazarov, L. Cultrera, W.J. Schaff
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • X.G. Jin
    Institute for Advanced Research, Nagoya, Japan
  • Y. Takeda
    Nagoya University, Nagoya, Japan
  
  Quantum efficiencies (QE) and mean transverse energies (MTE) of GaAs photocathodes grown using various techniques: metal-organic vapor phase epitaxy (MOVPE), molecular beam epitaxy (MBE), and atomic polishing have been compared and found to be identical. GaAs and GaInP based samples grown at Nagoya University were activated and measured in the Cornell ERL photoinjector. These were found to be in agreement with the samples measured at the ERL injector in KEK.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI057  
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MOPRI058 Metal Plasmonic Nanostructures Functionalized by Atomic Layer Deposition of MgO for Photocathode Applications electron, vacuum, resonance, emittance 739
 
  • S.V. Baryshev, S.P. Antipov, A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • M.R. Savina, A.V. Zinovev
    ANL, Argonne, Illinois, USA
  • E. Thimsen
    University of Minnesota, Minneapolis, USA
  
  Funding: Euclid TechLabs LLC acknowledges support from the DOE SBIR program, grant No. DE-SC0009572.
To create high current, long lasting electron sources capable of providing sub-ps bunches, new photocathode concepts are sought. Most recently, plasmonic nanostructured metal surfaces or flat metal surfaces activated by an ultrathin MgO are under great attention. We report on a photocathode design combining these two approaches. It consists of plasmonic Ag nanoparticles (NPs) functionalized by 3 MgO monolayers (MLs). Ag NPs were synthesized by an aerosol method and MgO was grown by atomic layer deposition (ALD). The NPs geometry was tuned to obtain broadband >50% absorption in the entire blue range as evidenced by UV-vis. spectroscopy. The WF of 3 MgO MLs/Ag NPs multilayer was reduced by 1 eV compared to bare NPs, from 5 to 4 eV, as evidenced by UPS and Kelvin probe. Reduction by 1 eV is maximal for this pair of materials, and agrees well with experimental and theoretical findings. While the effect on WF is indeed significant, a special handling protocol for Ag before depositing MgO is a must. It would preserve a clean Ag surface with a WF of nearly 4 eV to achieve 3 eV upon ALD of MgO. This and other issues are under study to promote photocathode applications. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI058  
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MOPRI059 Fabrication of Alkali Antimonide Photocathode for SRF Gun laser, gun, vacuum, SRF 742
 
  • E. Wang, S.A. Belomestnykh, I. Ben-Zvi, D. Kayran, G.T. McIntyre, T. Rao, J. Smedley, D. Weiss, W. Xu
    BNL, Upton, Long Island, New York, USA
  • I. Ben-Zvi, M. Ruiz-Osés
    Stony Brook University, Stony Brook, USA
  • X. Liang
    SBU, Stony Brook, New York, USA
  • H.M. Xie
    PKU, Beijing, People's Republic of China
  
  Funding: * This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE and DOE grant
The first alkali antimonide photocathode was prepared and inserted into the BNL 704 MHz SRF gun. An excimer laser cleaning system was installed in a cathode deposition chamber and the cleaning technique developed previously was used in the first cathode preparation. We also demonstrated that oxidized cathode can be removed by exposing it to the same excimer laser. In this paper, we show the set up of the incorporated laser cleaning system and the QE enhancement of alkali antimony photocathode. The vacuum evolution at transport cart and QE measurement system are also discussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI059  
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MOPRI063 Alkali Antimonide Photocathodes in a Can vacuum, gun, insertion, controls 745
 
  • J. Smedley, K. Attenkofer, T. Rao, S.G. Schubert
    BNL, Upton, Long Island, New York, USA
  • I. Ben-Zvi, X. Liang, E.M. Muller, M. Ruiz-Osés
    Stony Brook University, Stony Brook, USA
  • J. DeFazio
    PHOTONIS USA Pennsylvanis, Inc., Lancaster, Pennsylvania, USA
  • H.A. Padmore, J.J. Wong
    LBNL, Berkeley, California, USA
  • J. Xie
    ANL, Argonne, Illinois, USA
  
  Funding: Work was supported by the US DOE, under Contracts DE-AC02-05CH11231, DE-AC02-98CH10886, KC0407-ALSJNT-I0013, DE-FG02-12ER41837 and DE-SC0005713. Use of CHESS is supported by NSF award DMR-0936384.
The next generation of x-ray light sources will need reliable, high quantum efficiency photocathodes. These cathodes will likely be from the alkali antimonide family, which currently holds the record for highest average current achieved from a photoinjector. In this work, we explore a new option for delivering these cathodes to a machine which requires them: use of sealed commercial vacuum tubes. Several sealed tubes have been introduced into a vacuum system and separated from their housing, exposing the active photocathode on a transport arm suitable for insertion into a photoinjector. The separation has been achieved without loss of QE. These cathodes are compared to those grown via traditional methods, both in terms of QE and in terms of crystalline structure, and found to be similar. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI063  
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MOPRI064 First Test Results from SRF Photoinjector for the R&D ERL at BNL gun, SRF, cavity, electron 748
 
  • D. Kayran, Z. Altinbas, D.R. Beavis, S.A. Belomestnykh, I. Ben-Zvi, J. Dai, S. Deonarine, D.M. Gassner, R.C. Gupta, H. Hahn, L.R. Hammons, C. Ho, J.P. Jamilkowski, P. Kankiya, N. Laloudakis, R.F. Lambiase, V. Litvinenko, G.J. Mahler, L. Masi, G.T. McIntyre, T.A. Miller, D. Phillips, V. Ptitsyn, T. Rao, T. Seda, B. Sheehy, K.S. Smith, A.N. Steszyn, T.N. Tallerico, R. Than, R.J. Todd, E. Wang, D. Weiss, M. Wilinski, W. Xu, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
  • S.A. Belomestnykh, I. Ben-Zvi, J. Dai, L.R. Hammons, V. Litvinenko, V. Ptitsyn
    Stony Brook University, Stony Brook, USA
  
  Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE and DOE grant at Stony Brook, DE-SC0005713.
An ampere class 20 MeV superconducting Energy Recovery Linac (ERL) is presently under commissioning at Brookhaven National Laboratory (BNL). This facility enables testing of concepts relevant for high-energy coherent electron cooling, electron-ion colliders, and high repetition rate Free-Electron Lasers. The ERL will be capable of providing electron beams with sufficient quality to produce high repetition rate THz and X-ray radiation. When completed the SRF photoinjector will provide 2 MeV energy and 300 mA average beam current. The injector for the R&D ERL was installed in 2012, this includes a 704MHz SRF gun* with multi-alkali photocathode, cryo-system upgrade and a novel emittance preservation zigzag-like low energy merger system. We describe the design and major components of the R&D ERL injector then report the first experimental results and experiences learned in the first stage of beam commissioning of the BNL R&D ERL.
* Wencan Xu et al., “Commissioning SRF gun for the R&D ERL at BNL”, IPAC2013 proceedings, WEPWO085. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI064  
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MOPRI074 Conceptual Project Relativistic Electron Cooler for FAIR/HESR electron, proton, high-voltage, acceleration 774
 
  • V.V. Parkhomchuk, M.I. Bryzgunov, A.P. Denisov, V.M. Panasiuk, V.B. Reva
    BINP SB RAS, Novosibirsk, Russia
  • K. Aulenbacher, J. Dietrich
    HIM, Mainz, Germany
  • V. Kamerdzhiev
    FZJ, Jülich, Germany
  
  To develop a 4 MeV relativistic electron cooling system for the HESR storage ring, which is part of the future GSI facility FAIR, is proposed to further boost the luminosity even with strong heating effects of high-density internal targets. In addition the upgrade to 8 MeV of the relativistic electron cooler is essential for the future Electron Nucleon Collider (ENC@FAIR) project. The basic feature of the design are the power for magnet field coils at accelerating and decelerating column is generated by turbines (one option under investigation in this research group) operated on SF6 gas under pressure  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI074  
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TUPRO076 Initial Experimental Analysis into the eRHIC Polarized Electron Beam Transport System dipole, electron, operation, network 1217
 
  • C. Yeckel, E. Dobrin, P. Holen, R.C. Miller, M. Stangenes, K.A. Thompson, L.W. Thompson
    Stangenes Industries, Palo Alto, California, USA
  • I. Ben-Zvi, R.F. Lambiase, J. Skaritka, E. Wang
    BNL, Upton, Long Island, New York, USA
  
  Stangenes Industries is working closely with Brookhaven National Lab in the United States to develop the eRHIC future ion collider. The collider requires a polarized electron source with high average current, short bunch length and small emittance. An array of photocathodes with their beams funneled into a common trajectory is utilized to achieve the required beam current and cathode lifetime. Stangenes Industries is charged with delivering the prototype injector for preliminary beam studies that will lead to full implementation by 2020. This study focuses on the development of the of beam transport system extending from cathode to beam dump. A majority of the complexity involves the so called "combiner magnet" that acts as a high frequency-rotating dipole to bend each beam into the final common trajectory. Preliminary experiments into the feasibility of such a system are analyzed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO076  
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TUPME055 Room-temperature Burst-mode GHz and THz Pulse-train Photoinjector electron, laser, bunching, acceleration 1492
 
  • F.H. Chao, C.H. Chen, K.Y. Huang, Y.-C. Huang, Y.C. Wang, M.H. Wu
    NTHU, Hsinchu, Taiwan
  • P.J. Chou
    NSRRC, Hsinchu, Taiwan
  
  A photoinjector usually generates an electron pulse with few ps pulse duration repeating at 10-100 Hz. The low-pulse rate limits the data rate in a number of applications. Although high-repetition-rate operation is possible from a superconducting accelerator, the high cost and complexity of a superconducting system prevent it from being widely used. In this paper, we present our study toward a burst-mode GHz/THz pulse train photoinjector operating at room temperature. For the GHz operation mode, we self-develop a driver laser system, generating tens of laser pulses at 2.856 GHz in an adjustable 5-10 ns temporal envelope repeating at 10 Hz. Upon illuminating the photocathode with the driver laser, our S-band photoinjector (supported by Tsing Hua University, Beijing) is to generate a GHz electron pulse train with the same temporal structure as that of the driver laser pulses. For the THz operation mode, we illuminate the photocathode with two lasers, one being a typical UV gun-driver laser at 260 nm and the other being a mid-infrared laser at 100 THz. The UV laser induces photoemission and the infrared laser gates the emission current at 100 THz by virtue of the Schottky effect.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME055  
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WEPRO015 RF Injector Beam Dynamics Optimization for LCLS-II emittance, simulation, linac, brightness 1974
 
  • C. F. Papadopoulos, D. Filippetto, F. Sannibale
    LBNL, Berkeley, California, USA
  • P. Emma, T.O. Raubenheimer, J.F. Schmerge, L. Wang, F. Zhou
    SLAC, Menlo Park, California, USA
  
  Funding: This work was supported in part by the Work supported, in part, by the LCLS-II Project and by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231
LCLS-II is a proposal for a high repetition rate (>1 MHz) FEL, based on a CW, superconducting linac. The LCLS-II injector is being optimized by a collaboration from Cornell University, Fermilab, LBNL, and SLAC. There are a number of different possible technical choices for the injector including an rf gun or a high voltage DC gun. In this paper we present the status of the simulations for the injector optimization for an rf gun choice for LCLS-II. A multiobjective genetic optimizer is implemented for this reason, and optimized solutions for different bunch charges, corresponding to different operating modes, are presented. These operating points are also the initial part of the start-to-end simulations for LCLS-II. Finally, we discuss the trade-offs between compression and brightness conservation in the low energy (<100 MeV) part of the accelerator, as well as the status of sensitivity studies. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRO015  
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WEPRO019 Comparison of the NSLS-II Linac Model to Measurements linac, emittance, simulation, gun 1983
 
  • R.P. Fliller
    BNL, Upton, Long Island, New York, USA
  
  Funding: This manuscript has been authored by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy
The NSLS-II linac and associated transport lines were successfully installed and commissioned in the spring of 2012. Various beam measurements were performed to ensure that the linac met specifications and would be a suitable injector for the NSLS-II booster. In this paper we discuss the outcomes of these measurements and compare them to the model of the NSLS-II linac. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRO019  
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WEPRO055 Development of a Quasi 3-D Ellipsoidal Photo Cathode Laser System for PITZ laser, electron, emittance, simulation 2069
 
  • T. Rublack, M. Khojoyan, M. Krasilnikov, F. Stephan
    DESY Zeuthen, Zeuthen, Germany
  • A.V. Andrianov, E. Gacheva, E. Khazanov, A. Poteomkin, V. Zelenogorsky
    IAP/RAS, Nizhny Novgorod, Russia
  • I. Hartl, S. Schreiber
    DESY, Hamburg, Germany
  • E. Syresin
    JINR, Dubna, Moscow Region, Russia
  
  Funding: Funded by the German Federal Ministry of Education and Research (BMBF) project 05K10CHE in the framework of the German-Russian collaboration "Development and Use of Accelerator-Based Photon Sources".
3-D ellipsoidal photo cathode laser pulses are considered as the next step in optimization of photo injectors required for a successful operation of linac based free electron lasers. Significant improvements in electron beam emittance obtained from the beam dynamics simulations using such laser pulses compared to the conventional cylindrical pulses motivated the experimental studies in order to develop a laser system for quasi 3-D ellipsoidal pulses. The Institute of Applied Physics (Nizhny Novgorod, Russia) in collaboration with the Joint Institute of Nuclear Research (Dubna, Russia) and the Photo Injector Test facility at DESY, Zeuthen site (PITZ) is developing such a photo cathode laser system. Experimental tests of the laser system with photoelectron beam production are planned at PITZ. The laser pulse shaping is realized using the spatial light modulator technique. The laser system is capable of pulse train generation. First cross-correlation measurements were done demonstrating in principle the ability to generate and measure quasi ellipsoidal laser pulses. In this contribution the overall set-up, working principle and the actual progress of the development will be reported. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRO055  
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WEPRO103 Femtosecond Time-resolved Transmission Electron Microscopy using an RF Gun electron, gun, laser, emittance 2205
 
  • J. Yang, M. Gohdo, K. Kan, T. Kondoh, K. Tanimura, Y. Yoshida
    ISIR, Osaka, Japan
  • J. Urakawa
    KEK, Ibaraki, Japan
  
  The first prototype of RF gun based relativistic-energy electron microscopy has been constructed at Osaka University to study ultrafast structural dynamic processes in matter. The RF gun driven by a femtosecond laser has generated a 100-fs-pulse MeV electron beam with emittance of 0.1 mm-mrad and energy spread of 10-4. Both the electron diffraction and image measurements have been succeeded in the prototype using the femtosecond electron beam. In the diffraction measurement, an excellent quality of diffraction pattern was acquired with electron number of 106. The single-shot measurement is available in the prototype. In the image measurement, the TEM image was acquired with a total electron number of 108. The magnification was 3,000 times. In the next step, we will reduce further the emittance to increase the beam brightness on the sample, and then improve the spatial resolution to <10 nm.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRO103  
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WEPRO114 SALOME: An Accelerator for the Practical Course in Accelerator Physics quadrupole, electron, experiment, emittance 2235
 
  • V. Miltchev, D. Riebesehl, J. Roßbach, M. Trunk
    Uni HH, Hamburg, Germany
  • O. Stein
    CERN, Geneva, Switzerland
  
  SALOME (Simple Accelerator for Learning Optics and the Manipulation of Electrons) is a short low energy linear electron accelerator built by the University of Hamburg. The goal of this project is to give the students the possibility to obtain hands-on experience with the basics of accelerator physics. In this contribution the layout of the device will be presented. The most important components of the accelerator will be discussed and an overview of the planned demonstration experiments will be given.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRO114  
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WEPME001 Virtual Cathode Drive Laser Diagnostics with a Large Dynamic Range for a Continuous Wave SRF Photoinjector laser, electron, diagnostics, operation 2251
 
  • E. Panofski, A. Jankowiak, T. Kamps, G. Klemz
    HZB, Berlin, Germany
  
  Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Association
In a SRF photoinjector the close relationship between the laser pulse and the generated electron bunch parameters requires continuous monitoring of some of the laser pulse parameters. A laser diagnostic system, called virtual cathode, is a key part of a system that controls the stability of the laser. One of the main challenges for the virtual cathode is to cover the large dynamic range of the photocathode laser between commissioning at 120 Hz and operation at 1.3 GHz repetition rate with constant laser pulse parameters. The design of the virtual cathode as well as first measurements with a photocathode drive laser for the SRF injector test facility GunLab of BERLinPro will be presented. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME001  
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WEPME007 Multi-Bunch Generator Cavity cavity, impedance, electron, coupling 2267
 
  • E.A. Savin, S.V. Matsievskiy, Ya.V. Shashkov, N.P. Sobenin
    MEPhI, Moscow, Russia
  • A.A. Zavadtsev
    Nano, Moscow, Russia
  
  The concept of the six bunch generator cell for the washers and diaphragm loaded structure (Moscow Meson Factory) power supply is proposed. The required power is 0.8 MW on the 991 MHz frequency. The high-voltage electron gun produces electron bunches and puts them into the cylindrical resonator tuned to TE02 mode and operating frequency. Bunches produces RF field that takes energy from the following bunches and then energy transfer to the accelerating structure throw the tuned coupling system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME007  
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WEPME023 VIL410, CPI’s 1.3 GHz, 25 kW CW IOT Amplifier System operation, controls, insertion, embedded 2305
 
  • I. Igor, R. Army, P. Brown, S. Locke, R. Rizzo, R. Snyder, G. Solomon, M. Tracy, T.A. Treado
    CPI, Beverley, Massachusetts, USA
  
  The VIL10 Heatwave™ Inductive Output Tube (IOT) amplifier system has been developed to meet the requirements of superconducting RF accelerators. Two VIL410 systems were completed and delivered in April 2014. The VKL9130A1 IOT in the VIL410 provides up to 30 kW RF output power over a 5 MHz bandwidth centered at 1.30 GHz. It operates both CW and pulsed. The VIL410 amplifier has been designed to achieve very tight amplitude and phase control. The amplitude and phase ripple are specified to be better than 0.1% rms and better than 0.2 degrees rms, respectively. The stability of the output power is specified to be better than 0.2% over a 20 second period. In normal operation, smooth control of the output is accomplished via RF input from the low level system. The VIL410 uses CPI’s VSL3616 solid state power amplifier (SSPA) to drive the IOT. The VSL3616 is a 700 watt CW SSPA which operates at 250 watts CW in the VIL410. The VIL410 has an embedded processor that controls all internal functions of the amplifier system and interfaces directly to EPICS. The VIL410 can be operated locally using a LabView PC Host program or remotely by EPICS.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME023  
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WEPME025 Design and Performance of Ultimate Vacuum System for the AREAL Test Facility vacuum, gun, dipole, electron 2311
 
  • A.A. Gevorgyan, V.S. Avagyan, B. Grigoryan, T.H. Mkrtchyan, A.S. Simonyan, V. V. Vardanyan
    CANDLE SRI, Yerevan, Armenia
  
  The design specification of the AREAL test facility require the residual pressure at the level of 1nTorr with beam through entire vacuum chamber. We present the main features of the vacuum system, including the design and fabrication peculiarities of the dedicated components like dipole magnet stainless steel vacuum chamber and the cubes for beam diagnostic stations. The philosophy and instrumentation of the vacuum system are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME025  
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WEPME029 Development of a Field Emitter-based Extractor Gauge for the Operation in Cryogenic Vacuum Environments vacuum, cryogenics, ion, operation 2320
 
  • M. Lotz, O.K. Kester, St. Wilfert
    GSI, Darmstadt, Germany
  
  This paper presents an investigation of a CNT emitter-based extractor gauge which is designed for pressure reading in cryogenic ultra-high vacuum systems. The results show that the modified gauge works well in both room temperature and cryogenic vacuum environments. Furthermore, it could be demonstrated that the modified gauge responds much more sensitive to small pressure fluctuations in cryogenic environments than the same gauge type having a hot-filament cathode.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME029  
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WEPME030 Design and Construction of a Prototype Sputter ion Pump in ILSF ion, vacuum, operation, electron 2323
 
  • O. Seify, H. Ghasem, S. Kashani, J. Rahighi
    ILSF, Tehran, Iran
  • H. Ghasem
    IPM, Tehran, Iran
  
  Design and construction process of special kind of sputter ion pump is described briefly in this paper. In order to investigate the optimization of effective parameters in choosing and designing ILSF ion pumps, this pump has been designed and manufactured. By optimizing some parameters such as dimension and shape of penning cells, anode voltage, magnetic field and internal structure of pump, it is possible to significantly decrease the cost of construction and operation of synchrotron vacuum system. One of the most important advantages of this design, is that the initial parameters and finally internal structure of the prototype pump are changeable easily. The effect of parameters like anode voltage, magnetic field etc. on pumping speed and final pressure are described. With the existing optimization it is expected that an ultimate pressure of 1x10-11 Torr could be achieved.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME030  
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WEPME036 Simulation of the Trajectory of Electrons in a Magnetron Sputtering System of TiN with CST Particle Studio vacuum, electron, simulation, experiment 2341
 
  • J. Wang, L. Fan, Y.Z. Hong, W.L. Liu, X.T. Pei, K. Tang, Y. Wang, W. Wei, Y.H. Xu, B. Zhang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  Funding: National Nature Science Foundation of China under Grant Nos.11075157.
In the process of magnetron sputtering deposition, electromagnetic fields have an important influence on the trajectory of particle movement and the properties of the TiN thin film in many cases. Even for simple geometries, the analytical prediction for charged particles trajectories is extremely cumbersome, so numerical simulations are essential to obtain a better understanding of the possible effects and helpful to optimize the design of experimental facility and experimental process. A software of CST PARTICLE STUDIOTM has been used to simulate the effect of magnetic and electric fields on electrons trajectories in the process of film coating. According to the simulation results, the improvement measures of the system design and experimental process have been achieved. The author put forward the improvement measures on film coating process according to the simulation results. The result shows that it is feasible and convenient to use three dimensional tool in the simulation of trajectory of electrons in a magnetron sputtering system. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME036  
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WEPME039 Leak Propagation Dynamics for the HIE-ISOLDE Superconducting Linac vacuum, cryomodule, linac, simulation 2351
 
  • G. Vandoni, M. Ady, M.A. Hermann, R. Kersevan, D.T. Ziemianski
    CERN, Geneva, Switzerland
  
  In order to cope with space limitations of existing infrastructure, the cryomodules of the HIE-Isolde superconducting linac feature a common insulation and beam vacuum, imposing the severe cleanliness standard of RF cavities to the whole cryostat. Protection of the linac vacuum against air-inrush from the three experimental stations through the HEBT lines relies on fast valves, triggered by fast cold cathode gauges. To evaluate the leak propagation velocity as a function of leak size and geometry of the lines, a computational and experimental investigation is being carried out at CERN. A 28 m long tube is equipped with strain gauges installed on thin-walled flanges, as well as fast reacting glow discharge and cold-cathode gauges. A leak is opened by the effect of a cutting pendulum, equipped with an accelerometer for data acquisition triggering, on a thin aluminium window followed by a calibrated orifice. The air inrush dynamics is simulated by Test-Particle Monte Carlo in the molecular regime and by Finite Elements fluid dynamics in the viscous regime.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME039  
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WEPME055 Residual Gas in the 14 m-long Aluminium Vacuum System of the Storage Ring of Taiwan Photon Source: toward Ultra-high Vacuum vacuum, ion, storage-ring, photon 2396
 
  • T.Y. Lee, C.K. Chan, C.H. Chang, C.-C. Chang, S.W. Chang, Y.P. Chang, B.Y. Chen, J.-R. Chen, Z.W. Chen, C.M. Cheng, Y.T. Cheng, G.-Y. Hsiung, S-N. Hsu, H.P. Hsueh, C.S. Huang, Y.T. Huang, L.H. Wu, Y.C. Yang
    NSRRC, Hsinchu, Taiwan
  
  In the Taiwan Photon Source project, the storage ring includes 24 sectors (each of length 14 m) of an aluminium vacuum chamber system. The design, manufacture, cleaning, welding and assembly of the vacuum components were undertaken by the NSRRC vacuum group. The ultimate objective is to attain a leak-tight, ultra-high vacuum and a vacuum system with a small rate of outgassing. In this work, we used a residual-gas analyzer (RGA) to analyze the variation of residual gas during proceeding toward ultra-high vacuum. This process, which led the pressure down to ~10-11 torr, includes baking, operation of ion pumps, degassing of hot cathode gauges and activation of NEG pumps. When a sufficiently small low pressure is attained, the ion pumps are turned off to test the building up of pressure. The outgassing property and the variation of the residual gas of the aluminium chamber and the ion pumps can be measured.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME055  
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WEPRI042 Nb Coated HIE-ISOLDE QWR Superconducting Accelerating Cavities: From Process Development to Series Production cavity, niobium, cryomodule, SRF 2571
 
  • A. Sublet, I. Aviles Santillana, B. Bártová, S. Calatroni, N.M. Jecklin, I. Mondino, M. Therasse, W. Venturini Delsolaro, P. Zhang
    CERN, Geneva, Switzerland
  • M. Cantoni
    EPFL, Lausanne, Switzerland
  
  The new HIE-ISOLDE accelerator at CERN requires the production of 32 superconducting cavities (20 high-beta and 12 low-beta) in order to increase the energy of the rare isotope beam delivered to the experiments. The Quarter Wave Resonators (QWRs) cavities (0.3m diameter and 0.8m height) are made of OFE 3D-forged copper and are coated by DC-bias diode sputtering with a thin superconducting layer of niobium. Following a preliminary process development phase, the series production of the high-beta cavities has started. An overview of the development phase is presented, describing the key parameters varied to match the HIE-ISOLDE specifications (operation at 4.5 K with an accelerating field of 6 MV/m at 10W RF losses and Q0=4.5x108) and the resulting niobium film characteristics. The first series of cavities, produced using the baseline coating recipe, and their RF performance is reviewed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI042  
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WEPRI043 Implementation of Carbon Thin Film Coatings in the Super Proton Synchrotron (SPS) for Electron Cloud Mitigation dipole, electron, quadrupole, target 2574
 
  • P. Costa Pinto, T.C. Basso, A. Bellunato, P. Edwards, M. Mensi, A. Sublet, M. Taborelli
    CERN, Geneva, Switzerland
  
  Low Secondary Electron Yield (SEY) carbon thin films get rid of electron multipacting in accelerator beam pipes. Two magnetic cells of the SPS were coated with such material and installed. In total more than forty vacuum vessels and magnet interconnections were treated. The feasibility of the coating process was validated. The performance of the carbon thin film will be tested with LHC nominal beams after the end of the long shutdown 1. Particular attention will be drawn to the long term behaviour. This paper presents the sputtering techniques used to coat the different components; their characterization (SEY measurements on coupons, RF multipacting tests and pump down curves); and the technology to etch the carbon film in case of a faulty coating. The strategy to coat the entire SPS will also be exposed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI043  
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WEPRI050 Development and Test Results of a Quasi-waveguide Multi-cell Resonator cavity, niobium, impedance, HOM 2595
 
  • Z.A. Conway, A. Barcikowski, S.M. Gerbick, M. Kedzie, M.P. Kelly, J.S. Kerby, S.H. Kim, S.V. Kutsaev, R.C. Murphy, A. Nassiri, P.N. Ostroumov, T. Reid, T.L. Smith, A. Zholents
    ANL, Argonne, Illinois, USA
  
  Funding: Work supported by the U.S. Department of Energy, Offices of Nuclear Physics and Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
This paper reports the successful fabrication and test results of a novel 2815 MHz superconducting deflecting cavity operating in a TE-mode trapped in a quasi-waveguide structure with extremely high shunt impedance. The waveguide structure of this cavity allows for the free propagation of all higher order modes (HOMs) out of the cavity via the beam ports, eliminating the need for HOM dampers inside the cavity when operated with high beam current. The absence of HOM dampers greatly simplifies the cavity fabrication and operation at cryogenic temperatures. This cavity with its high shunt impedance is ideal for the spatial rotation of short bunches in a small physical space, a requirement for the generation of sub-picosecond short pulse x-rays in electron storage rings or luminosity upgrades of colliders. Results characterizing the fabrication accuracy and precision, the RF performance at 2 K, and frequency tuning considerations will be discussed here. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI050  
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WEPRI058 Commissioning Status of the Advanced Superconducting Test Accelerator at Fermilab gun, laser, cryomodule, cavity 2615
 
  • J. Ruan, R. Andrews, C.M. Baffes, D.R. Broemmelsiek, K. Carlson, B. Chase, M.D. Church, D.J. Crawford, E. Cullerton, J.S. Diamond, N. Eddy, D.R. Edstrom, E.R. Harms, A. Hocker, A.S. Johnson, A.L. Klebaner, M.J. Kucera, J.R. Leibfritz, A.H. Lumpkin, J.N. Makara, S. Nagaitsev, O.A. Nezhevenko, D.J. Nicklaus, L.E. Nobrega, P.S. Prieto, J. Reid, J.K. Santucci, G. Stancari, D. Sun, M. Wendt, S.J. Wesseln
    Fermilab, Batavia, Illinois, USA
  • P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  
  Funding: *Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The Advanced Superconducting Test Accelerator (ASTA) is under construction at Fermilab. This accelerator will consist of a photo-electron gun, injector, ILC-type cryomodules, and multiple downstream beam-lines. Its purpose is to be a user-based facility for Advanced Accelerator R&D. . Following the successful commissioning of the photoinjector gun, a Tesla style 8-cavity cryomodule and a high gradient capture cavity have been cooled down to 2 K and powered commissioning and performance characterization has begun. We will report on the commissioning status and near-term future plans for the facility. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI058  
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THOBB03 Novel Device for In-situ Thick Coatings of Long, Small Diameter Accelerator Vacuum Tubes vacuum, electron, target, plasma 2834
 
  • A. Hershcovitch, M. Blaskiewicz, J.M. Brennan, W. Fischer, C.J. Liaw, W. Meng, R.J. Todd
    BNL, Upton, Long Island, New York, USA
  • A.X. Custer, A.A. Dingus, M.Y. Erickson, N.Z. Jamshidi, R.R. Laping, H.J. Poole
    PVI, Oxnard, California, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
To alleviate the problems of unacceptable ohmic heating and of electron clouds, a 50 cm long cathode magnetron mole was fabricated and successfully operated to copper coat an assembly containing a full-size stainless steel cold bore RHIC magnet tubing connected to two types of RHIC bellows, to which two additional RHIC tubing pipes were connected. To increase cathode lifetime, movable magnet package was developed, and thickest possible cathode was made, with rather challenging target to substrate distance of less than 1.5 cm. The magnetron is mounted on a carriage with spring loaded wheels that successfully crossed bellows and adjusted for variations in vacuum tube diameter, while keeping the magnetron centered. Electrical power and cooling water are fed through a motorized spool driven umbilical cabling system, which is enclosed in a flexible braided metal sleeve. Optimized process to ensure excellent adhesion was developed. Coating adhesion of 10 μm Cu surpassed all industrial tests; exceeded maximum capability of a 12 kg pull test fixture. Details of experimental setup for coating two types of bellows and a full-scale magnet tube sandwiched between them will be presented. 		 
slides icon Slides THOBB03 [2.033 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THOBB03  
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THPRO028 Bunch Compressor Design for CLIC Drive Beam gun, linac, linear-collider, collider 2924
 
  • A.A. Aksoy
    Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey
  • J. Esberg, D. Schulte
    CERN, Geneva, Switzerland
  
  The drive-beam linac which is required for generation RF power at Compact Linear Collider (CLIC) has to accelerate an electron beam with 8.4 nC per bunch up to 2.4 GeV in almost fully loaded structures. The required beam stability in both transverse and longitudinal directions are of concern for such a high bunch charge. We present different bunch compressor designs for the Drive Beam and compare their performance including the effects beam energy and phase jitters.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO028  
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THPRO042 Field Emission Studies of Heat Treated Mo Substrates SRF, gun, electron, cavity 2955
 
  • R. Barday, A. Jankowiak, T. Kamps, C. Klimm, J. Knobloch, F. Siewert, A. Varykhalov
    HZB, Berlin, Germany
  • S. Lagotzky, G. Müller
    Bergische Universität Wuppertal, Wuppertal, Germany
  • B. Senkovskiy
    Technische Universität Dresden, Dresden, Germany
  
  Funding: This work was supported by German Bundesministerium für Bildung und Forschung project 05K13PX2, Land Berlin and grants of Helmholtz Association.
Molybdenum can be used as a substrate for the bi-alkali antimonide photocathodes utilized for the generation of high brightness electron beams in a superconducting radio frequency (SRF) photoinjector cavities. Operation at high field strength is required to obtain a low emittance beam, thus increasing the probability of field emission (FE) from the cathode surface. Usually, substrates are heated in situ before alkali de- position to remove oxide layers from the surface. FE on Mo substrates was measured by means of a field emission scanning microscope (FESM). It turned out that in situ heat treatment (HT) of the Mo surface significantly changes the FE behaviour by activation of new emitters. For a better understanding of the mechanism for enhanced emission after in situ heating a witness Mo sample was investigated using x-ray photoelectron spectroscopy. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO042  
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THPRO044 Report on Gun Conditioning Activities at PITZ in 2013 gun, cavity, vacuum, FEL 2962
 
  • M. Otevřel, P. Boonpornprasert, J.D. Good, M. Groß, I.I. Isaev, D.K. Kalantaryan, M. Khojoyan, G. Kourkafas, M. Krasilnikov, D. Malyutin, D. Melkumyan, T. Rublack, F. Stephan, G. Vashchenko
    DESY Zeuthen, Zeuthen, Germany
  • G. Asova
    INRNE, Sofia, Bulgaria
  • P. Boonpornprasert, S. Rimjaem
    Chiang Mai University, Chiang Mai, Thailand
  • F. Brinker, K. Flöttmann, S. Lederer, B. Marchetti, S. Schreiber
    DESY, Hamburg, Germany
  • Ye. Ivanisenko
    PSI, Villigen PSI, Switzerland
  • M.A. Nozdrin
    JINR, Dubna, Moscow Region, Russia
  • G. Pathak
    Uni HH, Hamburg, Germany
  • D. Richter
    BESSY GmbH, Berlin, Germany
  
  Recently three RF guns were prepared at the Photo Injector Test Facility at DESY, location Zeuthen (PITZ) for their subsequent operation at FLASH and the European XFEL. The gun 3.1 is a previous cavity design and is currently installed and operated at FLASH, the other two guns 4.3 and 4.4 were of the current cavity design and are dedicated to serve for the start-up of the European XFEL photo-injector. All three cavities had been dry-ice-cleaned prior their conditioning and hence showed low dark current levels. The lowest dark current level – as low as 60μA at 65MV/m field amplitude – has been observed for the gun 3.1. This paper reports in details about the conditioning process of the most recent gun 4.4. It informs about experience gained at PITZ during establishing of the RF conditioning procedure and provides a comparison with the other gun cavities in terms of the dark currents. It also summarizes the major setup upgrades, which have affected the conditioning processes of the cavities.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO044  
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THPRO051 Cavity Design for a S-Band Photoinjector RF Gun with 400 Hz Repetition Rate cavity, gun, FEL, emittance 2983
 
  • J.W. McKenzie, 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
  • V.V. Paramonov
    RAS/INR, Moscow, Russia
  
  As part of the design of CLARA (Compact Linear Accelerator for Research and Applications), the proposed UK FEL test facility at Daresbury Laboratory, a high repetition rate S-band photoinjector RF gun is being developed. This gun will be able to operate at up to 400 Hz repetition rate in single bunch mode. We present the initial cavity design including its optimisation for the beam dynamics of CLARA. We also present the initial cooling design for the cavity which will enable the high repetition rates to be achieved.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO051  
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THPRO093 Low Emittance Electron Beam Transportation in Compact ERL Injector gun, focusing, laser, solenoid 3104
 
  • T. Miyajima, K. Harada, Y. Honda, T. Kume, S. Nagahashi, N. Nakamura, T. Obina, S. Sakanaka, M. Shimada, R. Takai, T. Uchiyama, A. Ueda, M. Yamamoto
    KEK, Ibaraki, Japan
  • R. Hajima, R. Nagai, N. Nishimori
    JAEA, Ibaraki-ken, Japan
  • J.G. Hwang
    Kyungpook National University, Daegu, Republic of Korea
  
  For future light source based on Energy Recovery Linac (ERL), an injector, which consists of a photocathode DC gun and superconducting RF cavities, is a key part to generate a low emittance, short pulse and high bunch charge electron beam. In compact ERL (cERL) which is a test accelerator to develop key technologies for ERL, the generation of low emittance electron beam with 0.1 mm mrad normalized emittance and 390 keV beam energy from the photocathode DC gun, and the acceleration to 5.6 MeV by superconducting cavity, were demonstrated in the first beam commissioning. To keep the high quality in the beam transportation, understanding the beam optics, which is affected by not only the focusing effects due to the gun, solenoid magnets and RF cavities but also space charge effect, is required. In this presentation, we will show that how to measure and correct the focusing effect by experimental method. Using this method, we succeeded in correcting the analytical model to give the good agreement with the measured gun focusing for low charge beam. And, we will show the space charge effect for high bunch charge beam.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO093  
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THPME092 Status of Diamond Detector Development for Beam Halo Investigation at ATF2 electron, detector, vacuum, photon 3449
 
  • S. Liu, P. Bambade, F. Bogard, J-N. Cayla, H. Monard, C. Sylvia, T. Vinatier
    LAL, Orsay, France
  • N. Fuster-Martínez
    IFIC, Valencia, Spain
  • I. Khvastunov
    National Taras Shevchenko University of Kyiv, The Faculty of Physics, Kyiv, Ukraine
  • T. Tauchi, N. Terunuma
    KEK, Ibaraki, Japan
  
  Funding: Chinese Scholarship Council
We are developing a diamond detector for beam halo and Compton spectrum diagnostics after the interaction point (IP) of ATF2, a low energy (1.3 GeV) prototype of the final focus system for ILC and CLIC linear collider projects. Tests of a 500 μm thick sCVD diamond detector with a dimension of 4.5 mm×4.5 mm have been carried out with radioactive sources and with electron beam from PHIL low energy (<10 MeV) photo-injector at LAL. The tests at PHIL were done with different beam intensities in air, just after the exit window at the end of the beam line, to test the response of the diamond detector and the readout electronics. We have successfully detected signals from single electrons, using a 40 dB amplifier, and from an electron beam of 108 electrons, using a 24 dB attenuator. A diamond sensor with 4 strips has been designed and fabricated for installation in the vacuum chambers of ATF2 and PHIL, with the aim to scan both the beam halo (with 2 strips of 1.5 mm×4 mm) and the beam core (with 2 strips of 0.1 mm×4 mm) transverse distributions. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME092  
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THPME133 Bunch Length Measurement with 2-Cell RF-Deflector at Waseda University electron, cavity, gun, coupling 3556
 
  • T. Takahashi, Y. Nishimura, M. Nishiyama, K. Sakaue, M. Washio
    Waseda University, Tokyo, Japan
  • T. Takatomi, J. Urakawa
    KEK, Ibaraki, Japan
  
  We have been studying on a system to measure the length of electron bunch generated by a photocathode rf electron gun at Waseda University. We adopted the rf-deflector system which can convert the longitudinal distribution to transverse by sweeping the electron bunch. By using HFSS, we optimized the design of the 2 cell rf-deflector which is operating on π-mode, dipole (TM110-like) mode at 2856 MHz. The fabrication and the tuning of the rf deflector have successfully processed. We have installed the rf-deflector in the accelerator system of Waseda University, and performed the measurement of the bunch length. It is confirmed that this rf-deflector has the temporal resolution of 167fs with 700kW supply when the beam energy is 4.8MeV. This means that our rf-deflector system has possibility to measure the ultra-short bunch length. In this conference, the rf-deflector system in Waseda University, the result of the bunch length measurement, the performance of the rf-deflector and the future plan will be reported.
Work supported by JSPS Grant-in-Aid for Scientific Research (A) 10001690 and the Quantum Beam Technology Program of MEXT. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME133  
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THPME146 Bunch Length Measurement by Using a 2-Cell Superconducting RF Cavity in cERL Injector at KEK cavity, electron, experiment, gun 3596
 
  • J.G. Hwang, E.-S. Kim
    Kyungpook National University, Daegu, Republic of Korea
  • T. Miyajima
    KEK, Ibaraki, Japan
  
  The development of future light source and linear colliders require high quality electron beams with short bunch length. The measurement of the bunch length is important technique for future electron machine. In general, the bunch length was measured by using deflecting cavity which has the time dependent transverse electromagnetic field. However, the transverse electric field of 2-cell superconducting RF (SRF) cavity can also provide the correlation between the bunch length and beam size as like the role of the deflecting cavity in bunch length measurement. The deflection strength was calibrated by changing the RF phase and the beam offset because the strength of transverse electric field of RF cavity depends on the phase of RF field and the beam offset in the cavity. We will present new way to measure the bunch length by using 2-cell SRF cavity, which has the acceleration field of 15 MV/m, and the measured result with the bunch length of 3 ps in cERL injector.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME146  
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THPRI038 Simulation Study of Electron Gun for Six MeV Linac for X-Ray Cargo Inspection electron, gun, simulation, focusing 3847
 
  • S. Ahmadiannamin, F. AbbasiDavani, R. Ghaderi, F. Ghasemi
    sbu, Tehran, Iran
  • M. Lamehi Rashti
    IPM, Tehran, Iran
  • S. Zarei
    Nuclear Science and Technology Research, InstituteRadiation Application School, Tehran, Iran
  
  Electron guns are designed in different models. Output beam quality and efficiency of the linear accelerator for each application depends on choosing the suitable model of electron gun. The most common types are diode and triode electron guns. Simulation Study of diode electron gun of Six MeV Linac for X-Ray Cargo Inspection represented in this article. Vaughan analytical method was used to obtain the initial dimensions. In final stage, CST Particle Studio software used to obtain the dimensional details.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI038  
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THPRI043 Thermal-mechanical Analysis of the RF Structures for the ELI-NP Proposal gun, RF-structure, linac, HOM 3860
 
  • V. Pettinacci
    INFN-Roma, Roma, Italy
  • D. Alesini, L. Pellegrino
    INFN/LNF, Frascati (Roma), Italy
  • L. Palumbo
    URLS, Rome, Italy
  
  The room temperature RF structures in the ELI-NP Linac will operate in multi-bunch with high repetition rate (100 Hz). For these reasons they are subject to some kW of power dissipated on the internal cavities surfaces. The resulting thermal deformation of the cavities shapes could imply variations in their electromagnetic fields. To limit these effects and optimize the cooling design, a fully coupled ElectroMagnetic- Thermal-Mechanical analysis has been performed on the S-Band Radiofrequency Gun and on the C-Band multi-cell structures. In the paper the study done in Ansys Workbench with HFSS and Ansys Mechanical is reviewed  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI043  
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THPRI059 Field Emission Study of RF cavity in Static Magnetic Field gun, cavity, solenoid, electron 3905
 
  • T.H. Luo, D. Li
    LBNL, Berkeley, California, USA
  • W. Gai
    ANL, Argonne, Illinois, USA
  • J.H. Shao
    TUB, Beijing, People's Republic of China
  
  The RF cavity performance in solenoid magnetic field is crucial for the muon ionization cooling. Previous experiments have shown that the strong external magnetic field can significantly lower the maximum achievable RF voltage in the cavity. The mechanism of this performance degradation has been studied both analytically and experimentally, but so far no conclusive cause has been determined yet. In this paper, we propose an experiment to study the effect of a static B field on the field emission in the RF cavity, which hasn't been investigated before, and which can contribute to the cavity performance degradation in the solenoid field.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI059  
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THPRI076 Laser Triggered RF Breakdown Study Using an S-band Photocathode Gun laser, gun, experiment, HOM 3943
 
  • J.H. Shao, W. Gai
    ANL, Argonne, Illinois, USA
  • H.B. Chen, Y.-C. Du, W.-H. Huang, J. Shi, C.-X. Tang, L.X. Yan
    TUB, Beijing, People's Republic of China
  • C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • F.Y. Wang
    SLAC, Menlo Park, California, USA
  
  A laser triggered RF breakdown experiment was carried out with an S-band photocathode gun at Tsinghua University for attempting understanding of the RF breakdown processes. By systematic measurement of the time dependence of the breakdown current at the gun exit and the stored RF energy in the cavity, one might gain insight into the time evolution of RF breakdown physics. A correlation of the stored energy and field emission current has been analysed with an equivalent circuit model. Experimental details and analysis methods are reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI076  
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THPRI077 Electric Field Enhancement Study using an L-band Photocathode Gun gun, experiment, simulation, pick-up 3946
 
  • J.H. Shao, W. Gai
    ANL, Argonne, Illinois, USA
  • H.B. Chen, J. Shi
    TUB, Beijing, People's Republic of China
  • C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • F.Y. Wang, L. Xiao
    SLAC, Menlo Park, California, USA
  
  RF breakdown in high gradient accelerating structures is a fundamental problem that is still needed better understanding. Past studies have indicated that field emission, which is usually represented by electric field enhancement (i.e. β) produced from the Fowler-Nordheim plot, is strongly coupled to the breakdown problem. A controlled surface study using a high gradient L-band RF gun is being carried out. With a flat cathode, the maximum electric field on the surface reached 103 MV/m. And electric field as high as 565 MV/m on the surface was achieved by a pin-shaped cathode. The field enhancement factor was measured at different surface field during the conditioning process. Initial results of the study are presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI077  
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