Keyword: operation
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MO1A02 Status of the European XFEL linac, electron, undulator, klystron 7
 
  • H. Weise
    DESY, Hamburg, Germany
  
  Funding: Work supported by the respective funding agencies of the contributing institutes; for details please see http:www.xfel.eu
The European XFEL under construction in Hamburg, Northern Germany, aims at producing X-rays in the range from 260 eV up to 24 keV out of three undulators that can be operated simultaneously with up to 27,000 pulses per second. The FEL is driven by a 17.5 GeV superconducting linac. Installation of this linac is now finished and commissioning is next. First lasing is expected for spring 2017. The paper summarizes the status of the project. First results of the injector commissioning are given. 		 
slides icon Slides MO1A02 [28.909 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MO1A02  
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MOOP03 High Gradient Accelerating Structures for Carbon Therapy Linac impedance, linac, cavity, ion 44
 
  • S.V. Kutsaev, R.B. Agustsson, L. Faillace, E.A. Savin
    RadiaBeam, Santa Monica, California, USA
  • A. Goel, B. Mustapha, A. Nassiri, P.N. Ostroumov, A.S. Plastun
    ANL, Argonne, Illinois, USA
  • E.A. Savin
    MEPhI, Moscow, Russia
  
  Funding: This work was supported by the U.S. Department of Energy, Office of High Energy Physics, under contract 0000219678
Carbon therapy is the most promising among techniques for cancer treatment, as it has demonstrated significant improvements in clinical efficiency and reduced toxicity profiles in multiple types of cancer through much better localization of dose to the tumor volume. RadiaBeam, in collaboration with Argonne National Laboratory, are developing an ultra-high gradient linear accelerator, Advanced Compact Carbon Ion Linac (ACCIL), for the delivery of ion-beams with end-energies up to 450 MeV/u for 12C6+ ions and 250 MeV for protons. In this paper, we present a thorough comparison of standing and travelling wave designs for high gradient S-Band accelerating structures operating with ions at varying velocities, relative to the speed of light, in the range 0.3-0.7. In this paper we will compare these types of accelerating structures in terms of RF, beam dynamics and thermo-mechanical performance. 		 
slides icon Slides MOOP03 [3.497 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOOP03  
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MOOP08 Latest News on High Average RF Power Operation at PITZ gun, vacuum, cathode, Windows 59
 
  • Y. Renier, G. Asova, P. Boonpornprasert, J.D. Good, M. Groß, H. Huck, I.I. Isaev, D.K. Kalantaryan, M. Krasilnikov, O. Lishilin, G. Loisch, D. Melkumyan, A. Oppelt, T. Rublack, F. Stephan
    DESY Zeuthen, Zeuthen, Germany
  • G. Asova
    INRNE, Sofia, Bulgaria
  • M. Bousonville, S. Choroba, S. Lederer
    DESY, Hamburg, Germany
  • C. Saisa-ard
    Chiang Mai University, Chiang Mai, Thailand
  • Q.T. Zhao
    IMP/CAS, Lanzhou, People's Republic of China
  
  The Photo Injector Test Facility at DESY in Zeuthen (PITZ) develops, tests and characterizes high brightness electron sources for FLASH and European XFEL. Since these FELs work with superconducting accelerators in pulsed mode, also the corresponding normal-conducting RF gun has to operate with long RF pulses. Generating high beam quality from the photocathode RF gun in addition requires a high accelerating gradient at the cathode. Therefore, the RF gun has to ensure stable and reliable operation at high average RF power, e.g. 6.5 MW peak power in the gun for 650 μs RF pulse length at 10 Hz repetition rate for the European XFEL. Several RF gun setups have been operated towards these goals over the last years. The latest gun setup was brought into the PITZ tunnel on February 10th 2016 and its RF operation started on March 7th. This setup includes RF gun prototype 4.6 with a new cathode contact spring design and an RF input distribution which consists of an in-vacuum coaxial coupler, an in-vacuum T-combiner and 2 RF windows from DESY production. In this contribution we will summarize the experience from the RF conditioning of this setup towards high average RF power and first experience from the operation with photoelectrons.  
slides icon Slides MOOP08 [0.563 MB]  
poster icon Poster MOOP08 [0.367 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOOP08  
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MOOP11 Operation of the CEBAF 100 MV Cryomodules cryomodule, cavity, electron, controls 65
 
  • C. Hovater, T.L. Allison, R. Bachimanchi, G.H. Biallas, E. Daly, M.A. Drury, A. Freyberger, R.L. Geng, G.E. Lahti, R.A. Legg, C.I. Mounts, R.M. Nelson, T. E. Plawski, T. Powers
    JLab, Newport News, Virginia, USA
  
  Funding: Authored by JSA, LLC under U.S. DOE Contract DE-AC05- 06OR23177.
The Continuous Electron Beam Accelerator Facility (CEBAF) 12 GeV upgrade reached its design energy in December of 2015. Since then CEBAF has been delivering 12 GeV beam to experimental Hall D and 11 GeV to experimental halls A and B in support of Nuclear physics. To meet this energy goal, ten new 100 MV cryomodules (80 cavities) and RF systems were installed in 2013. The superconducting RF cavities are designed to operate CW at a average accelerating gradient of 19.2 MV/m. To support the higher gradients and higher QL (3.2×107) operations, the RF system uses 13 kW klystrons and digital LLRF to power and control each cavity. This paper reports on the C100 operation and optimization improvements of the RF system and cryomodules. 		 
slides icon Slides MOOP11 [1.574 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOOP11  
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MOPRC004 Beam Orbit Analysis and Correction of the FRIB Superconducting Linac linac, quadrupole, simulation, injection 71
 
  • Y. Zhang, Z.Q. He
    FRIB, East Lansing, USA
  
  Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
Beam based alignment (BBA) techniques are important tools for precise beam orbit correction of a high power linac, and supplement to the model based or orbit response matrix (ORM) based correction methods. BBA will be applied to beam orbit analysis and correction of the FRIB linac arcs where a beam orbit offset within 0.1 mm is required to the second order achromatic beam tuning. In this paper, we first introduce the study of model based beam orbit correction of the arc, and then a more precise orbit correction with BBA. Realistic misalignment of beam elements and beam position monitors (BPMs) are included in the simulation studies. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC004  
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MOPRC011 FRIB Lattice-Model Service for Commissioning and Operation simulation, lattice, database, software 90
 
  • D.G. Maxwell, Z.Q. He, G. Shen
    FRIB, East Lansing, USA
  
  Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DESC0000661, the State of Michigan and Michigan State University.
Accelerator beam simulation is crucial for the successful commissioning and operation of the FRIB linear accelerator. A primary requirement of the FRIB linear accelerator is to support a broad range of particle species and change states. Beam simulations must be performed for these various accelerator configurations and it is important the results be managed to ensure consistency and reproducibility. The FRIB Lattice-Model Service has been developed to manage simulation data using a convenient web-based interface, as well as, a RESTful API to allow integration with other services. This service provides a central location to store and organize simulation data. Additional features include search, comparison and visualization. The system architecture, data model and key features are discussed. 		 
poster icon Poster MOPRC011 [1.295 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC011  
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MOPRC029 Experiment of Plasma Discharge on HWR Cavity for In-Situ Surface Cleaning Study cavity, plasma, electron, experiment 133
 
  • A.D. Wu, Y. He, T.C. Jiang, C.L. Li, Y.M. Li, W.M. Yue, S.H. Zhang, H.W. Zhao
    IMP/CAS, Lanzhou, People's Republic of China
  • L.M. Chen
    Institute of Physics, Chinese Academy of Sciences, Beijing, People's Republic of China
  • L. Yang
    IHEP, Beijing, People's Republic of China
  
  Hydrocarbons, which migrate from the vacuum bumps system, will absorb on the cavity surface after periods of operation. The contaminants can reduce the surface electron work function to enhance the field emission effect and restrict the cavity accelerating gradient. The room temperature in-situ plasma surface processing to clean the hydrocarbon contaminants can act as a convenient and efficient technology for the accelerator on line performance recovery. For better control of the discharge inside the cavity, the experiment works on a single HWR cavity aims to research the ignition between the swarm parameters (gas flow, pressure, forward power).  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC029  
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MOPLR004 Development of an High Gradient, S-band, Accelerating Structure for the FERMI Linac linac, quadrupole, electron, wakefield 136
 
  • C. Serpico, I. Cudin
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • A. Grudiev
    CERN, Geneva, Switzerland
  
  The FERMI seeded free-electron laser (FEL), located at the Elettra laboratory in Trieste, is driven by a 200 meter long, S-band linac routinely operated at nearly 1.5 GeV and 10 Hz repetition rate [1]. The high energy part of the Linac is equipped with seven, 6 meter long Backward Traveling Wave (BTW) structures: those structures have small iris radius and a nose cone geometry which allows for high gradient operation [2]. Nonetheless a possible development of high-gradient, S-band accelerating struc-tures for the replacement of the actual BTW structures is under consideration. This paper investigates a possible solution for RF couplers that could be suitable for linac driven FEL where reduced wakefields effects, high oper-ating gradient and very high reliability are required.  
poster icon Poster MOPLR004 [0.947 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR004  
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MOPLR007 Redesign of the End Group in the 3.9 GHz LCLS-II Cavity HOM, cavity, dipole, linac 145
 
  • A. Lunin, I.V. Gonin, T.N. Khabiboulline, N. Solyak
    Fermilab, Batavia, Illinois, USA
  
  Funding: Operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the U.S. DOE
Development and production of Linac Coherent Light Source II (LCLS-II) is underway. The central part of LCLS-II is a continuous wave superconducting RF (CW SCRF) electron linac. The 3.9 GHz third harmonic cavity similar to the XFEL design will be used in LCLS-II for linearizing the longitudinal beam profile*. The initial design of the 3.9 GHz cavity developed for XFEL project has a large, 40 mm, beam pipe aperture for better higher-order mode (HOM) damping. It is resulted in dipole HOMs with frequencies nearby the operating mode, which causes difficulties with HOM coupler notch filter tuning. The CW linac operation requires an extra caution in the design of the HOM coupler in order to prevent its possible overheating. In this paper we present the modified 3.9 GHz cavity End Group for meeting the LCLS-II requirements
* LCLS-II 3.9 GHz Cryomodules, Physics Requirements Document, LCLSII-4.1-PR-0097-R1, SLAC, USA, 2015 		 
poster icon Poster MOPLR007 [1.590 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR007  
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MOPLR009 X-Band Travelling Wave Accelerating Section R&D for HTF electron, coupling, cavity, vacuum 152
 
  • K. Jin
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  Hefei Light Source (HLS) was mainly composed of an 800 MeV electron storage ring and an 800MeV-1GeV constant-gradient accelerator in NSRL. The new Linac with Full Energy Injection and the Top-up Injection scheme has been developed successfully. And the other functioning as X Ray Free Electron Laser test facility has been considered. In the project, in order to compress the bunch length and to achieve the beam energy distribution linearization. A 15MeV, operation frequency 11.424GHz traveling wave accelerating section as harmonic compensation is being developed. In this paper, X Ray Free Electron Laser Hefei Test Facility (HTF) is introduce briefly. And the R&D of the x-band accelerating section with collinear load are presented in detail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR009  
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MOPLR010 4 K SRF Operation of the 10 MeV CEBAF Photo-Injector cryomodule, SRF, cavity, cryogenics 155
 
  • G.V. Eremeev, M.A. Drury, J.M. Grames, R. Kazimi, M. Poelker, J.P. Preble, R. Suleiman, Y.W. Wang, M. Wright
    JLab, Newport News, Virginia, USA
  
  Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
SRF accelerating cavities are often operated in superfluid helium of temperature near 2 K to enhance the cavity quality factor Q0 and manage cryogenic heat loads, which are particularly important at large SRF accelerator facilities. This temperature paradigm, however, need not put SRF technology out of the reach of small institutions or even limit SRF operation at large facilities to provide 10-100 MeV beam energy. At the Jefferson Lab CEBAF accelerator there are regularly scheduled maintenance periods during which the liquid helium temperature is raised to 4 K, reducing cryogenic plant power consumption by ~50% and saving megawatts of electrical power. During such a recent period, we accelerated a continuous-wave electron beam at the CEBAF photo-injector to 6.3 MeV/c with current ~80μA using two niobium cavities at helium temperature of 4 K. This contribution describes the SRF and cryogenic performance and uses measured beam quality and energy stability as key metrics. These measurements indicate that 4 K operation of niobium SRF cavities in CEBAF and at small institutions may be a sensible and cost effective mode of operation, provided the cryogenic load associated with lower Q0 is manageable for the number of SRF cavities needed. For Jefferson Lab, this enhances our scientific reach allowing additional low-energy ~10 MeV experiments each year. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR010  
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MOPLR014 Construction of a Third Recirculation for the S-DALINAC* dipole, linac, recirculation, simulation 168
 
  • M. Arnold, T. Kürzeder, J. Pforr, N. Pietralla, M. Steinhorst
    TU Darmstadt, Darmstadt, Germany
  • F. Hug
    IKP, Mainz, Germany
  
  Funding: * Work supported by DFG through CRC 634 and RTG 2128
Since 1991 the superconducting recirculating electron accelerator S-DALINAC is running at TU Darmstadt. Its designated design energy of 130 MeV wasn't reached yet due to a lower quality factor of the 3 GHz cavities and thus a higher dissipated power to the helium bath. To increase the maximum achievable energy in cw operation from approx. 85 MeV to the design value of 130 MeV the main accelerator will be passed a fourth time. In this configuration the accelerating gradients of the cavities can be lowered, so that the resulting dissipated power will match the available cooling power of the cryo plant. To realize an additional main linac pass a new recirculation beam line is needed. The most crucial points are the design of the separation dipole and its mirrored version as well as a properly calculated lattice. For the implementation of a new recirculation beam line the existing sections must be adapted to fit the new boundary conditions. This contribution will present some aspects of the design and will report on the actual status of this project. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR014  
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MOPLR024 Progress Towards Nb3Sn CEBAF Injector Cryomodule cavity, cryomodule, niobium, electron 193
 
  • G.V. Eremeev, K. Macha, U. Pudasaini, C.E. Reece, A-M. Valente-Feliciano
    JLab, Newport News, Virginia, USA
  
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Operations at 4 K instead of 2 K have the potential to reduce the operational cost of an SRF linac by a factor of 3, if the cavity quality factor can be maintained. Cavities coated with Nb3Sn have been shown to achieve the accelerating gradients above 10 MV/m with a quality factor around 1010 at 4 K. Because such performance is already pertinent for CEBAF injector cryomodule, we are working to extend these results to CEBAF accelerator cavities envisioning coating of two CEBAF 5-cell cavities with Nb3Sn. They will be installed in an injector cryomodule and tested with beam. The progress on this path is reported in this contribution. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR024  
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MOPLR036 Study on Multilayer Thin Film Coating on Superconducting Cavity cryogenics, electromagnetic-fields, radio-frequency, controls 215
 
  • Y. Iwashita, Y. Fuwa, H. Tongu
    Kyoto ICR, Uji, Kyoto, Japan
  • H. Hayano, T. Kubo, T. Saeki
    KEK, Ibaraki, Japan
  • M. Hino
    Kyoto University, Research Reactor Institute, Osaka, Japan
  • H. Oikawa
    Utsunomiya University, Utsunomiya, Japan
  
  Funding: This research is supported by following programs: Grant-in-Aid for Exploratory Research 26600142 and Photon and Quantum Basic Research Coordinated Development Program from the MEXT.
Multilayer thin film coating is a promising technology to enhance performance of superconducting cavities. Until recently, principal parameters to achieve the sufficient performance had not been known, such as the thickness of each layer. We proposed a method to deduce a set of the parameters to exhibit a good performances. In order to verify the scheme, we are trying to make some experiments on the subject at Kyoto. The sample preparation and the test setup for the measurement apparatus will be discussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR036  
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MOPLR054 Progress and Operation Experiences of the J-PARC Linac linac, ion, ion-source, rfq 257
 
  • K. Hasegawa
    JAEA/J-PARC, Tokai-mura, Japan
  
  The J-PARC linac started beam commissioning in 2006 and has delivered beam to users since 2008. The linac had been operated with a beam energy of 181 MeV and a peak beam current of 15-20 mA, which corresponds to the 3 GeV Rapid Cycling Synchrotron (RCS) beam power of 300 kW. An energy of 400 MeV and higher peak beam current of 50 mA linac was required to reach the goal of the J-PARC project. For the beam energy upgrade, we installed a new accelerating structure, Annular-ring Coupled Structure linac (ACS) in 2013. The ion source and the Radio Frequency Quadrupole linac were replaced to increase the peak beam current in 2014. Since then, the linac provides beams to demonstrate a 1 MW equivalent beam at the RCS and also for routine operation for user programs. The progress and operation experiences of the J-PARC linac are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR054  
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MOPLR071 A 3-MeV Linac for Development of Accelerator Components at J-PARC linac, rfq, laser, ion 298
 
  • Y. Kondo, H. Asano, E. Chishiro, K. Hirano, T. Itou, Y. Kawane, N. Kikuzawa, S.I. Meigo, A. Miura, S. Mizobata, T. Morishita, H. Oguri, K. Ohkoshi, A. Ohzone, Y. Sato, S. Shinozaki, K. Shinto, H. Takei, K. Tsutsumi
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • Z. Fang, Y. Fukui, K. Futatsukawa, K. Ikegami, T. Miyao, K. Nanmo, T. Shibata, T. Sugimura, A. Takagi
    KEK, Ibaraki, Japan
  • T. Hori
    Nippon Advanced Technology Co., Ltd., Tokai, Japan
  • T. Ishiyama, T. Maruta
    KEK/JAEA, Ibaraki-Ken, Japan
  • M. Mayama, Y. Sawabe
    Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan
  
  We are constructing a linac for development of accelerator components at J-PARC. This linac consists of a H− ion source, a low energy beam transport (LEBT), an radio frequency quadrupole (RFQ) linac, and a diagnostics bean line. The beam energy is 3 MeV, the beam current is 30 mA, and the duty factor is 0.6%, which corresponds to 0.5 kW. The accelerator itself has a capacity of at least 1 kW. However, the beam power is limited by radiation dose, because there are no radiation shields between the accessible area during the operation. The source and LEBT are same as the J-PARC linac's. The RFQ is a used one in the J-PARC linac, called RFQ I. At first, we are planning to conduct experiments of the laser charge exchange development for the transmutation facility. Then, this linac will be used for the development accelerator components such as beam scrapers, bunch shape monitors, laser profile monitors, and so on. We will be able to install new devices into the actual J-PARC linac after the full testing. The development of H− ion source can be carried out at this system, and also RFQ in the future. In this paper, present status of this 3-MeV linac at J-PARC is presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR071  
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MOP106001 Energy Stability of ERLs and Recirculating Linacs linac, recirculation, cavity, simulation 304
 
  • R.G. Eichhorn, J. Hoke, Z. Mayle
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Energy recovery linacs can be seen as a hybrid between a linear and a circular accelerator. It has been shown in the past that an appropriate choice of the longitudinal working point can significantly improve the energy stability of a recirculating linac. In this contribution we will expand the concept of energy recovery linacs and investigate the energy spread of the beam as well as the recovery efficiency stability which can be a more demanding quantity in a high current ERL.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOP106001  
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MOP106012 MESA - an ERL Project for Particle Physics Experiments target, experiment, electron, linac 313
 
  • F. Hug, K. Aulenbacher, R.G. Heine, B. Ledroit, D. Simon
    IKP, Mainz, Germany
  
  The Mainz Energy-recovering Superconducting Accelerator (MESA) will be constructed at the Institut für Kernphysik of the Johannes Gutenberg University of Mainz. The accelerator is a low energy continuous wave (CW) recirculating electron linac for particle physics experiments. MESA will be operated in two different modes serving mainly two experiments: the first is the external beam (EB) mode, where the beam is dumped after being used with the external fixed target experiment P2, whose goal is the measurement of the weak mixing angle with highest accuracy. The required beam current for P2 is 150 μA with polarized electrons at 155 MeV. In the second operation mode MESA will be run as an energy recovery linac (ERL). The experiment served in this mode is a (pseudo) internal fixed target experiment named MAGIX. It demands an unpolarized beam of 1 mA at 105 MeV. In a later construction stage of MESA the achievable beam current in ERL-mode shall be upgraded to 10 mA. Within this contribution an overview of the MESA project will be given highlighting the latest accelerator layout and the challenges of operation with high density internal gas targets.
Work supported by DFG through cluster of excellence PRISMA, CRC 1044 and RTG 2128 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOP106012  
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MOP106023 Intra Bunch Train Transverse Dynamics in the Superconducting Accelerators FLASH and European XFEL cavity, beam-transport, HOM, transverse-dynamics 333
 
  • T. Hellert, W. Decking, M. Dohlus
    DESY, Hamburg, Germany
  
  At FLASH and the European XFEL accelerator superconducting 9-cell TESLA cavities accelerate long bunch trains at high gradients in pulsed operation. Several RF cavities with individual operating limits are supplied by one RF power source. Within the bunch train, the low-level-RF system is able to restrict the variation of the vector sum voltage and phase of one control line below 3·10-4 and 0.06 degree, respectively. However, individual cavities may have a significant spread of amplitudes and phases. Misaligned cavities in combination with variable RF parameters will cause significant intra-pulse orbit distortions, leading to an increase of the multi-bunch emittance. An efficient model including coupler kicks was developed to describe the effect at low beam energies. Comparison with start-to-end tracking and experimental data will be shown.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOP106023  
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TU1A05 High Power Operation of SNS SC Linac cavity, linac, ion, cryomodule 348
 
  • M.A. Plum
    ORNL, Oak Ridge, Tennessee, USA
  
  Funding: Work performed at (or work supported by) Oak Ridge National Laboratory, which is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
The SNS superconducting linac (SCL) provides 972 MeV, 1.5 MW H− beam for the storage ring and neutron spallation target. It has now been in operation for 11 years, and we have gained some experience in long-term operational issues. Three inter-related issues are gradient changes, errant beams, and trip rates. In this presentation we will provide an update on our progress to mitigate these issues, and also report on the overall status of the SCL. 		 
slides icon Slides TU1A05 [5.831 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TU1A05  
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TU2A01 State of the Art, Status and Future of RF Sources for Linacs klystron, linac, collider, status 353
 
  • E. Jensen
    CERN, Geneva, Switzerland
  
  This talk tries an overview of recent developments in RF sources for linear accelerators of different scales and for various applications, spanning a frequency range from about 100 MHz to X-band, spanning duty factors from about 10-3 to CW, and spanning power levels from a few kW up to hundreds of MW average. Exciting recent trends include new bunching concepts for klystrons promising a significant increase of efficiency and better power combiners paving the way to MW-class solid state power amplifiers.  
slides icon Slides TU2A01 [15.049 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TU2A01  
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TU2A02 Pulsed High Power Klystron Modulators for ESS Linac Based on the Stacked Multi-Level Topology klystron, linac, flattop, DTL 359
 
  • C.A. Martins, G. Göransson, M. Kalafatic
    ESS, Lund, Sweden
  • M. Collins
    Lund Technical University, Lund, Sweden
  
  ESS has launched an internal R&D project in view of designing, prototyping and validating a klystron modulator compatible with the requirements based on a novel topology named SML (Stacked Multi-Level). This topology is modular and based on the utilization of High Frequency (HF) transformers. The topology allows for the usage of industrial standard power electronic components at the primary stage at full extent which can easily be placed and wired in a conventional electrical cabinet. It requires only few special components like HF transformers, rectifiers and filters (i.e. passive components) to be placed in an oil tank. This arrangement allows scaling up in average and pulse power to the required levels while keeping the size, cost, efficiency and reliability of the different modules under good control. Besides the very good output pulse power quality, the AC grid power quality is also remarkably high with a line current harmonic distortion below 3%, a unitary power factor and an extremely reduced line voltage flicker below 0.3%. A reduced scale modulator prototype has been built and validated experimentally.  
slides icon Slides TU2A02 [8.596 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TU2A02  
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TUOP05 First Experiments at the CW-Operated RFQ for Intense Proton Beams rfq, ion, coupling, experiment 394
 
  • P.P. Schneider, D. Born, M. Droba, C. Lorey, O. Meusel, D. Noll, H. Podlech, A. Schempp, B. Thomas, C. Wagner
    IAP, Frankfurt am Main, Germany
  
  This contribution describes the first experiments with the cw-operated RFQ*, which is designed to accelerate protons from 120keV to 700keV for the FRANZ-Project**. The commissioning is done using the RF and ion beam scrubbing technique. In the first phase, the acceptance of the RFQ is scanned and the performance of the RFQ without space-charge effects is evaluated with a 2mA proton beam. The second phase will increase the beam current up to 50mA and a third phase with a machine upgrade for a beam current of up to 200mA is planned. The configuration of a high-current RFQ***, transporting beam current increasing from 2mA with no space-charge forces to a beam with high space-charge effects gives an unique insight in the beam optics of the space-charge effects. The measurements are done with a slit-grid emittance scanner for the transversal phase-space, a faraday cup for the transmitted current and a momentum spectrometer to measure the energy spread. The results set the basis for later experiments on variations of the beam current and the future coupling of the RFQ with an IH-structure****.
* Bechtold, A., et al., MOP001, LINAC08
** Meusel, O., et al., MO3A03, LINAC12
*** Vossberg, M., et al., WEPFI009, IPAC13
**** Heilmann, M., et al., THPWO017, IPAC13 		 
slides icon Slides TUOP05 [2.435 MB]  
poster icon Poster TUOP05 [4.550 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUOP05  
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TUPRC003 Effect of Number of Macro Particles on Time Evolution of Phase Space Distribution electron, emittance, simulation, linac 414
 
  • T. Miyajima
    KEK, Ibaraki, Japan
  
  Funding: This work was supported by JSPS KAKENHI Grant Number 26600147.
In particle tracking simulation with space charge effect, the macro-particle model, which has same mass-to-charge ratio, is widely used, since it does not require any symmetry of beam shape. However, selection of proper number of macro-particles is important, because the accuracy depends on it. Emittance, which is calculated by phase-space distribution, is especially affected by the number of macro-particles. In order to study the relation between the number of macro-particles and the resolution in the phase space, we defined a transformation, which describes reduction process of macro-particle number, and analyzed static phase space distribution. As a next step, we studied the effect of the macro-particle number on the dynamics of the phase space distribution for 1D charged particle distribution in the rest frame. The numerical result shows that the number of macro-particles affected the phase space distribution around the head and the tail of the bunch.
* T. Miyajima, "Effect of number of macro particles in phase space distribution", in Proc. of IPAC2015, Richmond, VA, USA, pp.242-244 (2015). 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPRC003  
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TUPRC007 An RFQ Based Neutron Source for BNCT rfq, simulation, cavity, neutron 427
 
  • X.W. Zhu, Z.Y. Guo, Y.R. Lu, H. Wang, Z. Wang, K. Zhu, B.Y. Zou
    PKU, Beijing, People's Republic of China
  
  Boron Neutron Capture Therapy (BNCT), promises a bright prospect for future cancer treatment, in terms of effectiveness, safety and less expanse. The PKU RFQ group proposes an RFQ based neutron source for BNCT. A unique beam dynamics design of 162.5 MHz BNCT-RFQ, which accelerates 20 mA of H+ from 30 keV to 2.5 MeV in CW operation, has been performed in this study. The Proton current will be about 20 mA. The source will deliver a neutron yield of 1.76×1013 n/sec/cm2 in the Li(p, n)Be reaction. Detailed 3D electromagnetic (EM) simulations of all components, including cross-section, tuners, pi-rods, and undercuts, of the resonant structure are performed. The design of a coaxial type coupler is developed. Two identical RF couplers will deliver approximately 153 kW CW RF power to the RFQ cavity. RF property optimizations of the RF structures are performed with the utilization of the CST MICROWAVE STUDIO.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPRC007  
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TUPRC024 Design and Implementation of an Automated High-Pressure Water Rinse System for FRIB SRF Cavity Processing cavity, SRF, alignment, controls 468
 
  • I.M. Malloch, E.S. Metzgar, L. Popielarski, S. Stanley
    FRIB, East Lansing, Michigan, USA
  
  Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE SC0000661, the State of Michigan and Michigan State University.
Traditionally, high-pressure water rinse (HPR) systems have consisted of relatively simple pump and rinse wand actuator systems intended to clean superconducting radio frequency (SRF) cavities during processing prior to test assembly. While these types of systems have proven effective at achieving satisfactory levels of cleanliness, large amounts of operator touch-labor are involved, especially in SRF cavities with complex geometries, where several fixture changes and cavity manipulations may be required. With this labor comes the risk of cavity damage or contamination, and the expense of the operator's time. To reduce this operator intervention and maximize cavity cleanliness and process throughput, a new, fully-automated, robotic HPR system has been commissioned in the Facility for Rare Isotope Beams (FRIB) cavity processing facility. This paper summarizes the design and commissioning process of the HPR system, and demonstrates improvements to the FRIB processing facility through the minimization of cavity contamination risk and reduction of technician labor through system automation. Comparative cavity RF test results are presented to further demonstrate system effectiveness. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPRC024  
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TUPLR022 Particulate Study on Materials for Cleanroom Assembly of SRF Cavities cavity, niobium, SRF, experiment 512
 
  • L. Zhao, A.V. Reilly
    JLab, Newport News, Virginia, USA
  
  Reducing particulates is an important aspect for clean-room operation. Knowing that it is impossible to completely eliminate all particulates in a clean room, efforts have been made to prevent particulates from entering SRF cavities during high pressure rinsing (HPR) and assembly. At Jefferson Lab, one practice to achieve this goal has been clamping covers to cavity open flanges during assembly. Several cover materials that have been used are examined and alternative candidate materials are under development. Clamps as a known particulate generator are carefully examined and cleaning efficiency of different methods is studied. Cover tests were done on different cavity flanges, including an LCLS-II beam pipe flange, which helps the selection of cover materials for prototype and production of the project.
Authored by Jefferson Science Associates, LLC under U.S. DOE Contracts DE-AC05-06OR23177 and DE-AC02-76SF00515 for the LCLS-II Project. 		 
poster icon Poster TUPLR022 [1.282 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR022  
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TUPLR044 Design and Operation of Pulsed Power Systems Built to ESS Specifications klystron, high-voltage, power-supply, electronics 558
 
  • M.K. Kempkes, M.P.J. Gaudreau, M.G. Munderville, I. Roth
    Diversified Technologies, Inc., Bedford, Massachusetts, USA
  • J. Domenge
    Sigma Phi Electronics, Wissembourg, France
  • J.L. Lancelot
    Sigmaphi, Vannes, France
  
  Diversified Technologies, Inc. (DTI), in partnership with SigmaPhi Electronics (SPE) has built three long pulse solid-state klystron transmitters to meet spallation source requirements. Two of the three units are installed at CEA Saclay and the National Institute of Nuclear and Particle Physics (IN2P3), where they will be used as test stands for the European Spallation Source (ESS). The systems delivered to CEA and IN2P3 demonstrate that the ESS klystron modulator specifications (115 kV, 25 A per klystron, 3.5 ms, 14 Hz) have been achieved in a reliable, manufacturable, and cost-effective design. There are only minor modifications required to support transition of this design to the full ESS Accelerator, with up to 100 klystrons. The systems will accommodate the recently-determined increase in average power (~660 kW), can offer flicker-free operation, are equally-capable of driving Klystrons or MBIOTs, and are designed for an expected MTBCF of over ten years, based on operational experience with similar systems.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR044  
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TUPLR045 Thyratron Replacement klystron, network, collider, medical-accelerators 561
 
  • I. Roth, M.P.J. Gaudreau, M.K. Kempkes, M.G. Munderville
    Diversified Technologies, Inc., Bedford, Massachusetts, USA
  
  Funding: *Work supported by DOE under contract DE-SC0011292
Semiconductor thyristors have long been used as a replacement for thyratrons in low power or long pulse RF systems. To date, however, such thyristor assemblies have not demonstrated the reliability needed for installation in short pulse, high peak power RF stations used with many pulsed electron accelerators. The fast rising current in a thyristor tends to be carried in a small region, rather than across the whole device, and this localized current concentration can cause a short circuit failure. An alternate solid-state device, the insulated-gate bipolar transistor (IGBT), can readily operate at the speed needed for the accelerator, but commercial IGBTs cannot handle the voltage and current required. It is, however, possible to assemble these devices in arrays to reach the required performance levels without sacrificing their inherent speed. Diversified Technologies, Inc. (DTI) has patented and refined the technology required to build these arrays of series-parallel connected switches. DTI is currently developing an affordable, reliable, form-fit-function replacement for the klystron modulator thyratrons at SLAC capable of pulsing at 360 kV, 420 A, 6μs, and 120 Hz. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR045  
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TUPLR053 Development and Measurements of a 325 MHz RFQ rfq, linac, proton, antiproton 578
 
  • M. Schütt, M.A. Obermayer, U. Ratzinger
    IAP, Frankfurt am Main, Germany
  • A. Schnase
    GSI, Darmstadt, Germany
  
  In order to have an inexpensive alternative to 4-Vane RFQs above 200 MHz, we study the possibilities of a Ladder-RFQ. The 325 MHz RFQ is designed to accelerate protons from 95 keV to 3.0 MeV according to the design parameters of the research program with cooled antiprotons at FAIR. This particular high frequency for an RFQ creates difficulties, which are challenging in developing a cavity, especially for 4-ROD RFQs, which dimensions become critically small with increasing the frequency. In order to define a satisfying geometrical configuration for this resonator, both from the RF and the mechanical point of view, different designs have been examined and compared. Very promising results were reached with a ladder type RFQ, which has been investigated since 2013. Due to its geometry, the manufacturing in terms of complexity, time and costs is more beneficial compared to welded accelerators. Furthermore, maintenance is easy to handle. The manufacturing, coppering and assembling of a 0.8 m prototype RFQ is finished. We present recent measurements of the RF-field including power measurements, frequency-tuning, field flatness as well as power measurements.  
poster icon Poster TUPLR053 [47.463 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR053  
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TUPLR056 Results of Operation of 162.5 MHz RFQ Couplers rfq, cavity, vacuum, multipactoring 584
 
  • S. Kazakov, J.P. Edelen, T.N. Khabiboulline, O.V. Pronitchev, J. Steimel
    Fermilab, Batavia, Illinois, USA
  
  Two couplers for RFQ of PXEI facility were designed and manufactured. Each coupler designed to deliver 50 KW, CW to RFQ at 162.5 MHz. Results of couplers operation are reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR056  
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TUP106007 Results of Intensity Upgrade Phase I for 200 MeV H− Linac at Brookhaven linac, ion, target, ion-source 634
 
  • D. Raparia, B. Briscoe, C. Cullen, T. Lehn, V. LoDestro, A. McNerney, J. Ritter, A. Zelenski
    BNL, Upton, Long Island, New York, USA
  
  The 200 MeV H− Linac has been operational for the last 45 years providing beam for the physics and isotope programs. Yearly integrated intensity delivered to BLIP has bean increased by six fold in past decade. Recently we have finish intensity, which resulted 40% more intensity for Brookhaven Linac Isotope Program (BLIP) and reduced losses along the linac and transfer line to BLIP by several folds. We will present detail of the upgrade and the future upgrades plane to further increase the intensity by factor of two  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUP106007  
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WE1A01 PIP-II Injector Test: Challenges and Status rfq, cryomodule, solenoid, SRF 641
 
  • P. Derwent, J.-P. Carneiro, J.P. Edelen, V.A. Lebedev, L.R. Prost, A. Saini, A.V. Shemyakin, J. Steimel
    Fermilab, Batavia, Illinois, USA
  
  The Proton Improvement Plan II (PIP-II) at Fermilab is a program of upgrades to the injection complex. At its core is the design and construction of a CW-compatible, pulsed H− superconducting RF linac. To validate the concept of the front-end of such machine, a test accelerator known as PXIE is under construction. It includes a 10 mA DC, 30 keV H− ion source, a 2 m-long Low Energy Beam Transport (LEBT), a 2.1 MeV CW RFQ, followed by a Medium Energy Beam Transport (MEBT) that feeds the first of 2 cryomodules increasing the beam energy to about 25 MeV, and a High Energy Beam Transport section (HEBT) that takes the beam to a dump. The ion source, LEBT, RFQ, and initial version of the MEBT have been built, installed, and commissioned. This report presents the overall status of the PXIE warm front end, including results of the beam commissioning through the installed components, and progress with SRF cryomodules and other systems.  
slides icon Slides WE1A01 [9.457 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-WE1A01  
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TH1A02 Operation of KOMAC 100 MeV Linac target, linac, ion, DTL 683
 
  • H.S. Kim
    KAERI, Daejon, Republic of Korea
  • Y.-S. Cho, H.-J. Kwon
    Korea Atomic Energy Research Institute (KAERI), Gyeongbuk, Republic of Korea
  
  Funding: This work was supported by the Ministry of Science, ICT & Future Planning of the Korean Government.
A 100-MeV proton linear accelerator at the KOMAC (Korea Multi-purpose Accelerator Complex) was under development for past 15 years, including preliminary design study period, and was successfully commissioned in 2013. The operation of the linac for user service started in July 2013 with two beam lines: one for a 20-MeV beam and the other for a 100-MeV beam. The linac is composed of a 50-keV microwave proton source, a 3-MeV four-vane-type RFQ (radio-frequency quadrupole) and a 100-MeV DTL (drift tube linac). In 2015, the linac operating time was more than 2,800 hours with an availability of better than 89% and unscheduled downtime was about 73 hours, mainly due to the ion source and HVCM problems. More than 2,100 samples from various fields such as material science, bio and nano technology and nuclear science, were treated in 2015. Currently, additional beamline for radioisotope production is being commissioned and a new beamline for low-flux irradiation experiments are under construction along with a continuous effort being made to increase the average beam power. 		 
slides icon Slides TH1A02 [18.355 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TH1A02  
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TH1A04 SARAF 4-Rods RFQ RF Power Line Splitting Design and Test rfq, proton, coupling, vacuum 693
 
  • J. Rodnizki, D. Hirschmann, Z. Horvitz, B. Kaizer, A. Perry, L. Weissman
    Soreq NRC, Yavne, Israel
  
  In the last years the SARAF 176 MHz 3.8 m long 4-rod RFQ accelerates routinely 2-4 mA CW proton beams to 1.5 MeV for basic studies in physics. However, it has not been successful in running CW deuteron beam for long periods. The findings imply that the RF coupler is the bottle neck to reach 250 kW CW dissipated power, equivalent to 65 kV inter-rod voltage, required to run the CW deuteron beam. A new design that splits the RFQ power between two couplers was built and commissioned successfully. A 3dB splitter and two new RF couplers were installed. The RF couplers improved design allows better brazing methods, vacuum properties and RF sealing. This design is innovative from two points of view: (a) implementation of two synchronized couplers located in two separated RF cells in a 4-rod RFQ. (b) The ability to run the RFQ in 200-250 kW to accelerate a 5 mA CW deuteron beam by 2.6 MV required for the new modulation design for 1.3 MeV/u. To our knowledge, SARAF RFQ will be the first 4-rod RFQ capable of running a CW deuteron beam at these power densities. This work may contribute to other 4-rod RFQ projects which intend to run CW beams in high dissipation power, like FRANZ and MYRRHA.  
slides icon Slides TH1A04 [6.109 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TH1A04  
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THOP05 Status and Operation of the ALBA Linac linac, klystron, injection, storage-ring 754
 
  • R. Muñoz Horta, D. Lanaia, F. Pérez
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
  
  The pre-injector of the ALBA Light Source is a Linac that delivers electrons up to a maximum energy of 125 MeV. It consist in a pre-bunching, a bunching and two accelerating sections feed by two 35 MW klystrons. Since July 2014, ALBA is operating in top-up mode, and the Linac is delivering 110 MeV electrons in multibunch mode every 20 minutes. Recently, new injection modes have been implemented and successfully tested. For one side, injection to the ALBA Booster is now also available with only one of the two klystrons in operation, and the Linac delivering a 67 MeV beam. On the other hand, the Linac single bunch mode has been integrated to the top-up operation application. By means of an algorithm, single bunch mode operation provides any kind of filling pattern in the ALBA storage ring, with single bunch shots injected to those buckets with lowest current. The performance of the Linac beam operated in these different modes is reported.  
slides icon Slides THOP05 [0.604 MB]  
poster icon Poster THOP05 [4.967 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THOP05  
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THOP09 Tuning of the CERN 750 MHz RFQ for Medical Applications rfq, linac, quadrupole, target 763
 
  • B. Koubek, Y. Cuvet, A. Grudiev, C. Rossi, M.A. Timmins
    CERN, Geneva, Switzerland
  
  CERN has built a compact 750 MHz RFQ as an injector for a hadron therapy linac. This RFQ was designed to accelerate protons to an energy of 5 MeV within only 2 m length. It is divided into four segments and equipped with 32 tuners in total. The RFQ length corresponds to 5λ which is considered to be close to the limit for simple field adjustment using tuners. Nevertheless the high frequency results in a sensitive structure and requires careful tuning by means of the alignment of the pumping ports and fixed tuners. This paper gives an overview of the tuning procedure and bead pull measurements of the RFQ.  
slides icon Slides THOP09 [16.367 MB]  
poster icon Poster THOP09 [23.832 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THOP09  
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THPRC015 Cool-Down Performance of the Cornell ERL Cryomodules cryomodule, cavity, linac, cryogenics 802
 
  • R.G. Eichhorn, F. Furuta, M. Ge, G.H. Hoffstaetter, M. Liepe, S.R. Markham, T.I. O'Connell, P. Quigley, D.M. Sabol, J. Sears, E.N. Smith, V. Veshcherevich, D. Widger
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  In the framework of the ERL prototyping, Cornell University has built two cryomodules, one injector module and one prototype Main Linac Cryomodule (MLC). In 2015, the MLC was successfully cooled down for the first time. We will report details on the cool-down as well as cycle tests we did in order to achieve slow and fast cool-down of the cavities. We will also report on the improvement we made on the injector cryomodule which also included a modification of the heat exchanger can that allows now a more controlled cool-down, too.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPRC015  
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THPRC017 Performance of SRF Cavity Tuners at LCLS II Prototype Cryomodule at FNAL cavity, cryomodule, SRF 808
 
  • J.P. Holzbauer, Y.M. Pischalnikov, W. Schappert, J.C. Yun
    Fermilab, Batavia, Illinois, USA
  
  Performances of the fast/slow tuners mounted on the 8 SRF cavities of first LCLS-II prototype cryomodule assembled at FNAL will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPRC017  
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THPRC025 Solid-State Pulsed Power System for a Stripline Kicker kicker, high-voltage, distributed, pulsed-power 824
 
  • N. Butler, M.P.J. Gaudreau, M.K. Kempkes, M.G. Munderville, F.M. Niell
    Diversified Technologies, Inc., Bedford, Massachusetts, USA
  
  Funding: *Work supported by DOE under contract DE-SC0004255
Diversified Technologies, Inc. (DTI) has designed, built, and demonstrated a prototype pulse amplifier for stripline kicker service capable of less than 5 ns rise and fall times, 5 to 90 ns pulse lengths, peak power greater than 13.7 MW at pulse repetition rates exceeding 100 kHz, and measured jitter under 100 ps. The resulting pulse is precise and repeatable, and will be of great interest to accelerator facilities requiring electromagnetic kickers. The pulse generator is based on the original specifications for the NGLS fast deflector. DTI's planar inductive adder configuration uses compensated-silicon power transistors in low inductance leadless packages with a novel charge-pump gate drive to achieve unmatched performance. The prototyping efforts guided the design of the full unit, however the magnetics and transmission line effects of the system were not revealed until the entire unit was assembled. The unit was brought to LBNL, compared with other researcher's efforts, and was judged very favorably. A number of development prototypes have been constructed and tested, including a successful 18.7 kV, 749 A unit. The modularity of this design will enable configuration of systems to a wide range of potential applications in both kickers and other high speed requirements, including high performance radars, directed energy systems, and excimer lasers. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPRC025  
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THPLR007 Dark Current Studies in ILC Main Linac linac, focusing, radiation, electron 855
 
  • A.I. Sukhanov, I.L. Rakhno, N. Solyak, I.S. Tropin
    Fermilab, Batavia, Illinois, USA
  
  Studies and optimization of design of the International Linear Collider (ILC) based on the TESLA-type 9-cell 1.3 GHz superconducting RF (SRF) cavities are currently underway. Dark current electron generated by field emission (FE) in SRF cavities can be captured and accelerated in the main ILC linac up to very high energy before they are removed by focusing and steering magnets. Dark current electrons, interacting with the materials surrounding SRF cavities, produce electromagnetic showers and contribute to the radiation in the main ILC tunnel. In this paper present preliminary results of the simulation study of dark current in the ILC linac.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR007  
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THPLR011 Traveling Wave Accelerating Structure Power Input Calculation With Equivalent Circuit Method coupling, impedance, interface, resonance 864
 
  • S.V. Matsievskiy, V.I. Kaminskiy
    MEPhI, Moscow, Russia
  
  Nowadays linac accelerating RF systems design is usually done by the finite difference method. It provides high accuracy of calculations and freedom in topology choosing, but may draw considerable amounts of computer resources with long calculation times. Alternative to this method, equivalent circuit method exists. The basic idea of this method is to build a lumped element circuit, which with certain approximation acts as an original accelerating cell. It drastically reduces the number of equations to solve. This method is long known but usually only used for the particular accelerating structures when speed of calculation is a key-factor. This paper describes an attempt to create more universal and user-friendly software application for calculating electrical field distribution in accelerating structures, provides mathematical equations this software is based on. The resulting application may be used for preliminary calculations of acceleration structures and help to determine cells electrodynamic parameters reducing overall design time.  
poster icon Poster THPLR011 [0.789 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR011  
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THPLR019 A Laser Pulse Controller for the Injector Laser at FLASH and European XFEL laser, timing, undulator, hardware 882
 
  • C. Grün, S. Schreiber, T. Schulz
    DESY, Hamburg, Germany
  
  FLASH is a multi-beamline free-electron laser user facility which provides femtosecond long high brilliant photon pulses in the extreme-UV and soft-X ray wavelength range. One pulsed superconducting linac accelerates electron bunches for two undulator beamlines, while a third beamline is under construction. Within each RF-pulse, trains of hundreds of electron bunches are produced in a photo-cathode RF gun, accelerated in the linac and distributed by fast kickers into the undulator beamlines. In order to fulfill the parameter ranges of the multiple user experiments each bunch train can be tuned individually in bunch number from 0 - 800, spacing from 1 μs - 25 μs and intensity from 0.1 nC - 1 nC. To make this possible, three injector laser systems are used and this allows FLASH to vary independently the laser settings for the designated undulator beamlines. A laser controller has been developed to make a multi-users operation mode possible. The controller uses a Field Programmable Gate Array (FPGA) to control the time structure of the laser pulses and it provides the interface for the timing and the machine protection system. The controller has been implemented using the MicroTCA.4 technology. The controller was ported to the injector laser system at the European XFEL facility and is in operation since end 2015.  
poster icon Poster THPLR019 [1.967 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR019  
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THPLR025 Modernisation of the 108 MHz RF Systems at the GSI UNILAC controls, cavity, PLC, LLRF 898
 
  • B. Schlitt, G. Eichler, S. Hermann, M. Hoerr, M. Mueh, S. Petit, A. Schnase, G. Schreiber, W. Vinzenz, J. Zappai
    GSI, Darmstadt, Germany
  
  A substantial modernisation of the RF systems at the 108 MHz Alvarez type post-stripper section of the GSI heavy ion linac UNILAC was launched in 2014 to prepare the existing facility for the future FAIR operation. A new 1.8 MW RF cavity amplifier prototype for low duty-cycle operation (2 ms pulse length at 10 Hz repetition rate) based on the widely-used tetrode TH558SC was designed and built by THALES and is under commissioning. A call for tenders was started for a 150 kW solid state driver amplifier. An RF test bench for the amplifier prototypes is in preparation at GSI including new control racks, commercial grid power supplies, and a modern PLC system for amplifier control. The existing powerful 1 MVA anode power supplies will be reused and are also being equipped with new PLC systems. The development of a digital low-level RF system based on the MTCA.4 standard and commercial vector modulator and FPGA boards was started. Status and details of the modernisation as well as first commissioning results of the new high power amplifier prototype will be reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR025  
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THPLR035 FZJ SRF TSR with Integrated LHe Vessel cavity, simulation, SRF, electromagnetic-fields 926
 
  • E.N. Zaplatin
    FZJ, Jülich, Germany
  
  Single- or Multi-Spoke SRF cavities are one of the basic accelerating structures for the low and intermediate energy part of many accelerators. Different types of external loads on the resonator walls predetermine the main working conditions of the SC cavities. The most important of them are very high electromagnetic fields that result in strong Lorentz forces acting on cavity walls and the pressure on cavity walls from the helium tank that also deforms the cavity shape. For the accelerators operating in pulsed regime the Lorentz forces are the dominant factor. The liquid helium vessel pressure instability even for 2K operations is the source of large microphonics and dominates for cw operation. Here we propose an innovative integrated helium vessel-cavity and stiffener design that will provide an effective passive damping minimizing df/dp ratio. Minimizing df/dp may be accomplished without an enhancement of the structure rigidity, which in turn minimizes the load on the cavity tuner. A separate stiffening scheme reducing Lorentz force cavity detuning to be added without violation of df/dp optimization. The developed at the Research Center in Jülich, Germany (FZJ) the 352 MHz, β=v/c=0.48 Triple-Spoke Resonator was used as an example to demonstrate the proposed conceptual integrated helium vessel-cavity design.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR035  
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THPLR044 First Performance Test on the Superconducting 217 MHz CH Cavity at 4.2 K cavity, linac, controls, low-level-rf 953
 
  • F.D. Dziuba, M. Amberg, M. Basten, M. Busch, H. Podlech
    IAP, Frankfurt am Main, Germany
  • W.A. Barth, M. Miski-Oglu
    GSI, Darmstadt, Germany
  • W.A. Barth, M. Miski-Oglu
    HIM, Mainz, Germany
  
  Funding: HIM, GSI, BMBF Contr. No. 05P15RFRBA, EU Project MYRTE
At the Institute for Applied Physics (IAP) of Frankfurt University a superconducting (sc) 217 MHz Crossbar-H-mode (CH) cavity with 15 accelerating cells and a gradient of 5.5 MV/m has been designed. The cavity is the key component of the demonstrator project at GSI which is the first stage to a new sc continuous wave (cw) linac for the production of Super Heavy Element (SHE) in the future. A successful and reliable beam operation of this first prototype will be a milestone on the way to the proposed linac. After fabrication at Research Instruments (RI) GmbH, Germany, the cavity without helium vessel has been commissioned at the new cryogenic test facility of the IAP with low level rf power at 4 K. The results of this first cold test will be presented in this contribution. 		 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR044  
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THPLR045 Operation Mode and Machine State Control for FRIB Driver Linac Operation linac, ion, controls, heavy-ion 956
 
  • M. Ikegami, D. Dudley, M.G. Konrad, Z. Li, G. Shen, V. Vuppala
    FRIB, East Lansing, USA
  
  Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
FRIB is a heavy ion linac facility to accelerate all stable ions up to 200 MeV/u with the beam power of 400 kW under construction at Michigan State University. It is required for FRIB driver linac to support various modes of operation with different ion species, charge states, beam energy and so on to meet requirements from experiments. In this paper, we describe overall design of operation modes, machine states, and software to manage transitions of those mitigating the risk of machine damage in FRIB. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR045  
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THPLR051 High-Power RF Test of IFMIF-EVEDA RFQ at INFN-LNL rfq, cavity, controls, vacuum 975
 
  • E. Fagotti, L. Antoniazzi, M.G. Giacchini, F. Grespan, M. Montis, A. Palmieri
    INFN/LNL, Legnaro (PD), Italy
  
  A partial test at full power and CW duty cycle will be performed at INFN-LNL on the last elements of the IFMIF RFQ, approximately two meters of structure, using a specific electromagnetic boundary element on the low energy end. The aim is to reach, in the RFQ coupled with its power coupler system, after an adequate period of conditioning, cw operation at nominal field level (132 kV between electrodes) for at least two hours without breakdown. The description of the experimental setup and procedure, as well as the main results of the conditioning procedure will be reported in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR051  
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THPLR054 Recent RF and Mechanical Developments for the ESS RFQ rfq, cavity, vacuum, simulation 978
 
  • N. Misiara, A. Albéri, G. Bourdelle, A.C. Chauveau, D. Chirpaz-Cerbat, M. Desmons, A.C. France, M. Lacroix, P.-A. Leroy, J. Neyret, G. Perreu, O. Piquet, B. Pottin, H. Przybilski, N. Sellami
    CEA/IRFU, Gif-sur-Yvette, France
  
  The ESS Radio-Frequency Quadrupole (RFQ) is a 4-vane resonant cavity designed at the frequency of 352.21 MHz frequency. It must accelerate and bunch a 70 mA proton beams from 75 keV to 3.62 Mev of energy with a 4% duty cycle. The current 3D design evolved and is currently divided in 5 segments for a total length of 4.54 m. This paper presents a complete radiofrequency (RF) analysis using the ANSYS Multiphysics 3D RF simulating code HFSS and a RFQ 4-wire transmission line model (TLM). It describes the integrated cooling strategy based on a coupling between the RF power losses and the thermo-mechanical physics in order to allow a proper RFQ tuning once under operation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR054  
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THPLR059 Status of a 325 MHz High Gradient CH - Cavity cavity, linac, ion, resonance 982
 
  • A. Almomani, U. Ratzinger
    IAP, Frankfurt am Main, Germany
  
  Funding: BMBF with contract number 05P12RFRB9
The reported linac developments aim on compact ion accelerators and on an increase of the effective accelerat-ing field (voltage gain per meter). Within a funded pro-ject, a high gradient Crossbar H-type CH-cavity operat-ed at 325 MHz was developed and successfully built at IAP-Frankfurt. The effective accelerating field for this cavity is expected to reach about 13.3 MV/m at a beam energy of 12.5 AMeV, corresponding to β=0.164. The results from this cavity might influence the later energy upgrade of the Unilac at GSI Darmstadt. The aim is a compact pulsed high current ion accelerator for significantly higher energies up to 200 AMeV. Detailed investigations for two different types of copper plating (high lustre and lustre less) with respect to the high spark limit will be performed on this cavity. The 325 MHz GSI 3 MW klystron test stand is best suited for these investigations. Additionally, operating of normal conducting cavities for the case of very short RF pulses will be discussed at cryogenic temperature. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR059  
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THPLR063 RF Design of a Deuteron Beam RFQ rfq, cavity, dipole, simulation 996
 
  • C.X. Li, W.P. Dou, Y. He, F.F. Wang, Z.J. Wang, X.B. Xu, Z.L. Zhang
    IMP/CAS, Lanzhou, People's Republic of China
  
  In a material irradiation facility in IMP, a RFQ is required for accelerating deuteron beam from 20 keV/u to 1.52 MeV/u. The structure design of the RFQ is drawing on the experience of the RFQ of Injector II of China ADS LINAC. Four-vane structure is adopted and the operation frequency is 162.5 MHz. Inter vane voltage is 65 kV and the Kilpatrick factor is 1.4. Π-mode stabilizing loops are used to move the dipole modes away from the working mode. Slug tuners are used to compensate for capacitance errors induced by machining. Cutbacks and end plate are modified to reach a reasonable field flatness. After the structure design and optimization, the simulation results of the cavity frequency is 162.459 MHz, the power loss is 109 kW. The multiphysics simulations are also performed to determine the frequency shift caused by the shift of the cooling water temperature.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR063  
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THPLR065 Beam Commissioning Status and Results of the FNAL PIP2IT Linear Accelerator RFQ rfq, experiment, proton, controls 1002
 
  • J. Steimel, C.M. Baffes, P. Berrutti, J.-P. Carneiro, J.P. Edelen, T.N. Khabiboulline, L.R. Prost, V.E. Scarpine, A.V. Shemyakin
    Fermilab, Batavia, Illinois, USA
  • A.L. Edelen
    CSU, Fort Collins, Colorado, USA
  • M.D. Hoff, A.R. Lambert, D. Li, T.H. Luo, J.W. Staples, S.P. Virostek
    LBNL, Berkeley, California, USA
  • V.L. Sista
    BARC, Mumbai, India
  
  Funding: Operated by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359 with the United States Department of Energy.
An H− beam was accelerated through a continuous wave (CW) capable, 4-vane, radio frequency quadrupole (RFQ) at Fermilab that was designed and constructed at Berkeley Lab. This RFQ is designed to accelerate up to 10 mA H− beam from 30 keV to 2.1 MeV in a test accelerator (PIP2IT). This paper presents results of specification verification and commissioning. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR065  
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