Keyword: acceleration
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MOZGBE1 Development of Gas Stripper at RIBF plasma, target, electron, heavy-ion 41
 
  • H. Imao
    RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama, Japan
 
  Charge strippers are almost inevitable for accelerations in heavy-ion accelerator complex. The fixed solid strip-pers including carbon-foil strippers are difficult to be used in on-going or upcoming new-generation in-flight RI beam facilities, e.g., RIBF (RIKEN, Japan), FAIR (GSI, Germany), FRIB (NSCL/MSU, US), HIAF (IMP, China) and RAON (RISP, Korea). The He gas stripper developed at RIBF is the first successful stripper significantly be-yond the applicable limit of the fixed carbon-foil strip-pers. We discuss the development of the gas strippers at RIBF and overview the related new-generation strippers being developed in the world.  
slides icon Slides MOZGBE1 [11.802 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBE1  
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MOPMF013 eRHIC EIC: Plans for Rapid Acceleration of Polarized Electron Bunch at Cornell Synchrotron polarization, electron, synchrotron, resonance 108
 
  • F. Méot, E.C. Aschenauer, H. Huang, C. Montag, V. Ptitsyn, V.H. Ranjbar, E. Wang, Z. Zhao
    BNL, Upton, Long Island, New York, USA
  • I.V. Bazarov, D. L. Rubin
    Cornell University, Ithaca, New York, USA
  • L. Cultrera, G.H. Hoffstaetter, K.W. Smolenski, R.M. Talman
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • D. Gaskell, O. Glamazdin, J.M. Grames
    JLab, Newport News, Virginia, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
An option as an injector into the polarized-electron storage ring of eRHIC EIC is a rapid-cycling synchrotron (RCS). Cornell's 10 GeV RCS injector to CESR presents a good opportunity for dedicated polarized bunch rapid-acceleration experiments, it can also serve as a test bed for source and polarimetry developments in the frame of the EIC R&D, as polarized bunch experiments require disposing of a polarized electron source, and of dedicated polarimetry in the linac region and in the RCS proper. This is as well an opportunity for a pluri-disciplinary collaboration between Laboratories. This paper is an introduction to the topic, and to on-going activities towards that EIC R&D project.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF013  
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MOPMF072 On the Feasibility of a Pulsed 14 TeV C.M.E. Muon Collider in the LHC Tunnel collider, luminosity, proton, SRF 296
 
  • V.D. Shiltsev, D.V. Neuffer
    Fermilab, Batavia, Illinois, USA
 
  We will consider technical feasibility, key machine parameters and major challenges of the recently proposed 14 TeV c.m.e. muon-muon collider in the LHC tunnel.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF072  
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MOPMF076 Energy Spread Compensation in Arbitrary Format Multi-Bunch Acceleration With Standing Wave and Traveling Wave Accelerators beam-loading, positron, cavity, linac 307
 
  • M. Kuriki
    HU/AdSM, Higashi-Hiroshima, Japan
 
  In the E-driven ILC (International Linear Collider) positron source, the beam is generated and accelerated in a multi-bunch format with mini-trains. The macro-pulse contains 2 to 8 mini-trains with several train gaps, because the pulse format is a copy of a part of the bunch storage pattern in DR (Damping Ring). This pulse format causes a variation of the accelerator field in the pulse due to the transient beam loading and an intensity fluctuation of captured positron. In this article, we discuss the compensation of the energy spread of such beam in standing wave and traveling wave accelerators. For standing wave accelerator, it can be compensated by switching input RF at appropriate timings. For traveling wave accelerator, it can be compensated by amplitude modulation of the input RF.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF076  
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MOPMF077 A Design Study of the Electron-driven ILC Positron Source Including Beam Loading Effect positron, beam-loading, cavity, booster 311
 
  • H. Nagoshi, M. Kuriki
    HU/AdSM, Higashi-Hiroshima, Japan
  • S. Kashiwagi
    Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
  • K. Negishi
    Iwate University, Morioka, Iwate, Japan
  • T. Omori, M. Satoh, Y. Seimiya, J. Urakawa
    KEK, Ibaraki, Japan
  • Y. Sumitomo
    LEBRA, Funabashi, Japan
  • T. Takahashi
    Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
 
  The International Linear Collider (ILC) is a next-generation accelerator for high-energy physics to study the Higgs and top sector in the Standard Model, and new physics such as supersymmetry and dark matter. ILC positron source based on Electron-driven method has been proposed as a reliable technical backup. In this article, we report the design study of the positron source based on the off-the-shelf RF components. The positron is generated and accelerated in a multi-bunch format. To compensate the energy variation by the transient beam loading effect, we employ AM (Amplitude Modulation) technique and the results were 16.60 ± 0.14 MV (peak-to-peak) for L-band 2m cavity driven by 22.5 MW power and 25.76 ± 0.19 MV (peak-to-peak) for S-band 2m ac-celerator driven by 36 MW power with 0.78 A beam load-ing.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF077  
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MOPML011 Liquid Cluster Ion Beam Processing of Transition Metal Films vacuum, radiation, target, experiment 415
 
  • D. Shimizu, H. Ryuto, M. Takeuchi, D. Yamamoto
    Kyoto University, Photonics and Electronics Science and Engineering Center, Kyoto, Japan
 
  The irradiation effects of cluster ion beams are characterized by the high-density collision of molecules that comprise the clusters against a target. According to molecular dynamics calculations, the local temperature of the colliding cluster and the surface of the target are expected to increase to several thousand K. The enhancement of the chemical interactions between the molecules in the colliding clusters and the atoms on the target surface is expected, if polyatomic molecules, such as ethanol and acetone, are used for the source material of the cluster. So, the irradiation effects of the polyatomic liquid cluster ion beams on transition metal films have been studied to examine the possibility of utilizing the liquid cluster ion beam technique for the processing of transition metal films. The transition metal films were formed by magnetron sputtering. The liquid clusters were produced by the adiabatic expansion method and ionized by electron ionization. The sputtering yields of transition metal films induced by liquid cluster ions are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML011  
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MOPML025 Slow Extraction Optimization at the MedAustron Ion Therapy Center: Implementation of Front End Acceleration and RF Knock Out extraction, proton, synchrotron, kicker 453
 
  • A. De Franco, L. Adler, F. Farinon, N. Gambino, G. Guidoboni, G. Kowarik, M. Kronberger, C. Kurfürst, S. Myalski, S. Nowak, M.T.F. Pivi, C. Schmitzer, I. Strašík, P. Urschütz, A. Wastl
    EBG MedAustron, Wr. Neustadt, Austria
  • L.C. Penescu
    Abstract Landscapes, Montpellier, France
 
  Funding: This project has received funding from the European Union's Horizon 2020 research and Innovation programme under the Marie Skłodowska-Curie grant agreement No 675265.
MedAustron is a synchrotron-based ion therapy center allowing tumour treatment with protons and other light ion species, in particular C6+. Commissioning of all fixed lines, two horizontal and one vertical, has been completed for protons and in parallel to the commissioning of a gantry and C6+, a facility upgrade study is progressing. The upgrade study encompasses the optimization of the slow extraction mechanism by employing the RF empty bucket channeling and RF Knock Out techniques. The former is a front end acceleration technique that suppress spill ripples, fundamental to safely operate the machine at the highest intensities. The latter is an alternative extraction technique which opens up interesting possibilities for fast beam energy and intensity modulations. In this work, we quantify spill smoothening effect achieved with the first and report the results of a feasibility study of the second using a Schottky monitor as a transverse kicker.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML025  
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MOPML034 Development Status of Superconducting RF Transmission Electron Microscope cavity, LLRF, gun, SRF 481
 
  • N. Higashi, A. Enomoto, Y. Funahashi, T. Furuya, X.J. Jin, Y. Kamiya, S. Michizono, F. Qiu, M. Yamamoto
    KEK, Ibaraki, Japan
  • S. Yamashita
    University of Tokyo, Tokyo, Japan
 
  Now we are developing a new type of transmission electron microscope (TEM) employing the accelerator technologies. In place of a DC thermal gun generally used in conventional TEMs, we apply a photocathode gun and a special-shaped superconducting cavity, named two-mode cavity. The two-mode cavity has two resonant modes of TM010 (1.3 GHz) and TM020 (2.6 GHz). To superimpose these, we can suppress the increase of the energy spread, which is needed for the high-spatial-resolution TEMs. We have already developed some prototypes of the photocathode gun and two-mode cavity, and now in the middle of the performance tests. In this presentation, we will show the latest status of the development.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML034  
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TUXGBE2 Study of Ultra-High Gradient Acceleration in Carbon Nanotube Arrays plasma, electron, wakefield, experiment 599
 
  • J. Resta-López, A.S. Alexandrova, V. Rodin, Y. Wei, C.P. Welsch, G.X. Xia
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • Y. M. Li, Y. Zhao
    UMAN, Manchester, United Kingdom
 
  Solid-state based wakefield acceleration of charged particles was previously proposed to obtain extremely high gradients on the order of 1 − 10 TeV/m. In recent years the possibility of using either metallic or carbon nanotube structures is attracting new attention. The use of carbon nanotubes would allow us to accelerate and channel particles overcoming many of the limitations of using natural crystals, e.g. channeling aperture restrictions and thermal-mechanical robustness issues. In this paper, we propose a potential proof of concept experiment using carbon nanotube arrays, assuming the beam parameters and conditions of accelerator facilities already available, such as CLEAR at CERN and CLARA at Daresbury. The acceleration performance of carbon nanotube arrays is investigated by using a 2D Particle-In-Cell (PIC) model based on a multi-hollow plasma. Optimum experimental beam parameters and system layout are discussed.  
slides icon Slides TUXGBE2 [27.296 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUXGBE2  
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TUXGBE4 Beam Quality Limitations of Plasma-Based Accelerators plasma, electron, laser, injection 607
 
  • A. Ferran Pousa, R.W. Aßmann
    DESY, Hamburg, Germany
  • A. Martinez de la Ossa
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
 
  Plasma-based accelerators are a promising novel technology that could significantly reduce the size and cost of future accelerator facilities. However, the typical quality and stability of the produced beams is still inferior to the requirements of Free Electron Lasers (FELs) and other applications. We present here our recent work in understanding the limitations of this type of accelerators, particularly on the energy spread and bunch length, and possible mitigating measures for future applications, like the plasma-based FEL in the EuPRAXIA design study.  
slides icon Slides TUXGBE4 [4.910 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUXGBE4  
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TUXGBF4 ORBIT Simulation, Measurement and Mitigation of Transverse Beam Instability in the Presence of Strong Space Charge in the 3-GeV RCS of J-PARC simulation, impedance, injection, space-charge 620
 
  • P.K. Saha, H. Harada, N. Hayashi, H. Hotchi, Y. Shobuda, F. Tamura
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
 
  The transverse impedance of eight extraction pulse kicker magnets (KM) is extremely strong source of transverse beam instability in the 3-GeV RCS (Rapid Cycling Synchrotron) at J-PARC. To realize the designed 1 MW beam power, collective beam dynamics with including the space charge effect for the coupled bunch instabilities excited by the KM impedance and associated measures were studied by incorporating all realistic time-dependent machine parameters in the ORBIT 3-D particle tracking code. The simulation results were all reproduced by measurements and, as a consequence, an acceleration of 1 MW beam power has been successfully demonstrated. In order to maintain variation of the RCS parameters required for multi-user operation, realistic measures for beam instability mitigation were proposed and also been successfully implemented in reality. To further increase the RCS beam power, beam stability issues and possible measures beyond 1 MW beam power are also considered.  
slides icon Slides TUXGBF4 [2.246 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUXGBF4  
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TUYGBE3 Recent progress of short pulse dielectric two-beam acceleration linear-collider, collider, experiment, wakefield 640
 
  • J.H. Shao, M.E. Conde, D.S. Doran, W. Gai, W. Liu, N.R. Neveu, J.F. Power, C. Whiteford, E.E. Wisniewski, L.M. Zheng
    ANL, Argonne, Illinois, USA
  • C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
 
  Two-Beam Acceleration (TBA) is a structure-based wakefield acceleration method with the potential to meet the luminosity and cost requirements of a TeV class linear collider. The Argonne Wakefield Accelerator (AWA) facility is developing a dielectric-based short pulse TBA scheme with the potential to withstand high acceleration gradients and to achieve low fabrication cost. Recently, the dielectric short pulse TBA technology was successfully demonstrated using K-band 26 GHz structures, achieving 55 MW output power from the power extractor and 28 MeV/m gradient in the accelerator. To improve the generated rf power, an X-band 11.7 GHz power extractor has been developed, which obtained 105 MW in the high power test. In addition, a novel dielectric disk accelerator (DDA) is currently under investigation to significantly increase the efficiency of linear colliders based on short pulse TBA. Details of these research will be presented in this paper.  
slides icon Slides TUYGBE3 [2.224 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUYGBE3  
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TUYGBF3 An EBIS-Based Low-Energy Accelerator for Fine-Focussed Ion Beams ion-source, electron, target, emittance 647
 
  • M. Schmidt, P. Laux, G.H. Zschornack
    DREEBIT, Großröhrsdorf, Germany
 
  Technologies based on focused ion beams have become indispensable for research institutions as well as commercial laboratories and high-tech production facilities (micro- and nanotechnology, semiconductor technology). We report on a compact setup combining an Electron Beam Ion Source (EBIS), a Wien filter for ion species separation, and a fine focusing ion acceleration column capable of producing ion beams with beam diameters in the micrometer range at ion beam energies up to the MeV range. Almost all elements of the periodic system can be injected into the EBIS to produce a broad spectrum of ion charge states with only one ion source. The beam energy of a selected ion species can easily be varied by changing the electric potential of the EBIS drift tube in which the ions are generated, resulting in different implantation depths in various solids. We present studies on beam diameter and emittance, available charge states, and SEM imaging as application.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUYGBF3  
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TUPAF010 Empty Sweeping Bucket for Slow Extraction extraction, resonance, hadrontherapy, synchrotron 676
 
  • L. Falbo, E. Bressi, C. Priano
    CNAO Foundation, Milan, Italy
 
  The extraction process from a synchrotron is one of the most important aspects of an accelerator devoted to clinical purposes, like the hadrontherapy in which hadron beams are used to treat tumors. Indeed the quality of the dose delivered to the patient, in terms of dose uniformity and precision in the beam characteristics, is defined by the way in which the beam is extracted. The quality of the extracted beam (the so called spill) is strongly affected by the stability of the power supplies of the synchrotron magnets whose field stability creates a ripple in the intensity of the extracted beam itself. When it is not possible to improve the power supply stability, it is needed to apply some additional techniques in order to cure the spill ripple. At CNAO, the italian hadrontherapy facility, it has been thought to improve the Empty Bucket Channelling technique by using an energy-moving bucket instead of a stationary bucket. The paper shows the implementation, the advantages and the efficacy of this RF gymnastic, named 'Empty Sweeping Bucket'.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF010  
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TUPAF087 A Two-Stage Splitring-RFQ for High Current Ion Beams at Low Frequencies rfq, simulation, impedance, resonance 941
 
  • M. Baschke, H. Podlech, A. Schempp
    IAP, Frankfurt am Main, Germany
 
  Funding: HIC for FAIR, BMBF Contr. No. 05P15RFRBA
For several accelerator projects RFQs are the first stage of acceleration. To reach high intensities a new Splitring-RFQ is investigated. Not only a high current and high beam quality/brilliance should be achieved, also a good tuning flexibility and comfort for maintenance are part of the study. The RFQ will consist of two stages with 27 MHz and 54 MHz to accelerate ions with an A/q of 60 up to energies of 200 keV/u. RF simulations with CST MWS have been performed to obtain the quality factor, shunt impedance and voltage distribution as well as tuning possibilities. The results and the status of the project will be presented.
 
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TUPAK004 Superconducting CH-Cavity Heavy Ion Beam Testing at GSI cavity, linac, heavy-ion, emittance 962
 
  • W.A. Barth, M. Heilmann, A. Rubin, A. Schnase, S. Yaramyshev
    GSI, Darmstadt, Germany
  • K. Aulenbacher
    IKP, Mainz, Germany
  • K. Aulenbacher, F.D. Dziuba, V. Gettmann, T. Kürzeder, M. Miski-Oglu
    HIM, Mainz, Germany
  • M. Basten, M. Busch, H. Podlech, M. Schwarz
    IAP, Frankfurt am Main, Germany
 
  Recently the first section of a standalone superconducting (sc) continuous wave (cw) heavy ion Linac as a demonstration of the capability of 217 MHz multi gap Crossbar H-mode structures (CH) has been commissioned and extensively tested with beam from the GSI- High Charge State Injector. The demonstrator set up reached acceleration of heavy ions up to the design beam energy and beyond. The required acceleration gain was achieved with heavy ion beams even above the design mass to charge ratio at high beam intensity and full beam transmission. This contribution presents systematic beam measurements with varying RF-amplitudes and phases of the CH-cavity, as well as versatile phase space measurements for heavy ion beams with different mass to charge ratio. The worldwide first and successful beam test with a superconducting multi gap CH-cavity is a milestone of the R&D work of Helmholtz Institute Mainz (HIM) and GSI in collaboration with Goethe University Frankfurt (GUF) in preparation of the sc cw heavy ion Linac project and other cw-ion beam applications.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAK004  
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TUPAK012 Conceptual Design of a Single-Ended MA Cavity for J-PARC RCS Upgrade cavity, operation, vacuum, power-supply 987
 
  • M. Yamamoto, M. Nomura, T. Shimada, F. Tamura
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • M. Furusawa, K. Hara, K. Hasegawa, C. Ohmori, Y. Sugiyama, M. Yoshii
    KEK, Tokai, Ibaraki, Japan
 
  The J-PARC RCS employes Magnetic Alloy (MA) loaded cavities and rf power is fed by vacuum tubes in push-pull operation. The multi-harmonic rf driving and the multi-harmonic beam loading compensation are realized due to the broadband characteristics of the MA. However, the push-pull operation has disadvantages in the multi-harmonics. An unbalance of the anode voltage swing remarkably appears at very high intensity beam acceleration. In order to avoid the unbalance, a single-ended MA cavity is considered for the RCS beam power upgrade because no unbalance arises intrinsically. We will describe the conceptual design of the single-end MA cavity for the RCS upgrade.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAK012  
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TUPAK016 Commissioning of the Diagnostic Beam Line for the Muon RF Acceleration with H Ion Beam Derived from the Ultraviolet Light quadrupole, diagnostics, experiment, MMI 997
 
  • Y. Nakazawa, H. Iinuma
    Ibaraki University, Ibaraki, Japan
  • N. Kawamura, T. Mibe, M. Otani, T. Yamazaki
    KEK, Ibaraki, Japan
  • R. Kitamura
    University of Tokyo, Tokyo, Japan
  • Y. Kondo
    JAEA/J-PARC, Tokai-mura, Japan
  • N. Saito
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • Y. Sue
    Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
 
  Funding: This work is supported by JSPS KAKENHI Grant Numbers JP15H03666, JP16H03987, and JP16J07784.
A muon LINAC is under development for a precise measurement of muon g-2 / EDM at J-PARC. We conducted an experiment of a muon RF acceleration on October and December 2017. The surface muon beam is irradiated to a metal degrader to generate slow negative muonium. The slow negative muoniums are accelerated to 90 keV with an electrostatic accelerator and an RFQ. Prior to muon RF acceleration, we conducted a commissioning of the diagnostic beam line consisting of two quadrupole magnets and a bending magnet. The ultraviolet light is irradiated to an aluminum foil and H ion is generated. It simulates a negative muonium and is accelerated with an electrostatic accelerator. This system allowed us to check operation for the diagnostic beam line, which is essential task for transportation and momentum selection of the negative muonium. In this paper, I would like to report the performance evaluation of the diagnostic beam line by H ions.
 
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TUPAL009 Studying a Prototype of Dual-beam Drift Tube Linac DTL, cavity, rfq, simulation 1020
 
  • T. He, L. Lu, W. Ma, L.P. Sun, C.C. Xing, X.B. Xu, L. Yang
    IMP/CAS, Lanzhou, People's Republic of China
 
  For generating high-intensity ion beams from linear ac-celerators, a multi-beam acceleration method which in-volves multiple accelerating beams to suppress the defo-cusing force from space charge effects, then integrating these beams by a beam funneling system, has been pro-posed. An Inter-digital H-mode (IH) two-beam type radio frequency quadrupole (RFQ) with accelerating 108mA (54mA/channel×2) carbon ion from 5 to 60 keV/ u and an IH four-beam RFQ with accelerating 160.8mA (40.2mA/channel×4) carbon ion from 3.6 to 41.6 keV/u had been successfully designed for low energy heavy ion acceleration [1]. In order to demonstrate that an IH dual-beam drift tube linac (DB-DTL) is suitable for high-intensity heavy ion beam acceleration in middle energy region, we has been developing a DB-DTL prototype by using three dimensional electromagnetic CST MicroWave Studio (MWS) and using particles tracking Pi Mode Linac Orbit Calculation (PiMLOC) [2-3]. According to the simulation results, the beam dynamics design and elec-tromagnetic design will be presented in this paper.
* Shota. Iketa et al., Nucl. Instr. and Meth. in Phys. Res. B.239-243 (2017).
 
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TUPAL015 Progress in the Realization and Commissioning of the Exotic Beam Facility SPES at INFN-LNL rfq, cyclotron, target, proton 1035
 
  • G. Bisoffi, A. Andrighetto, P. Antonini, L. Bellan, D. Benini, J. Bermudez, D. Bortolato, M. Calderolla, M. Comunian, S. Corradetti, A. Facco, E. Fagotti, P. Favaron, A. Galatà, F. Galtarossa, M.G. Giacchini, F. Gramegna, A. Lombardi, M. Maggiore, M. Manzolaro, D. Marcato, T. Marchi, P. Mastinu, P. Modanese, M.F. Moisio, A. Monetti, M. Montis, A. Palmieri, S. Pavinato, D. Pedretti, A. Pisent, M. Poggi, G.P. Prete, C. R. Roncolato, M. Rossignoli, L. Sarchiapone, D. Scarpa, D. Zafiropoulos, L. de Ruvo
    INFN/LNL, Legnaro (PD), Italy
  • V. Andreev
    ITEP, Moscow, Russia
  • M.A. Bellato
    INFN- Sez. di Padova, Padova, Italy
  • A.J. Mendez
    ORNL, Oak Ridge, Tennessee, USA
 
  SPES (Selective Production of Exotic Species) is an ISOL type facility for production and post-acceleration of exotic nuclei for forefront research in nuclear physics. Radioactive (RA) species (A=80/160) will be produced by fissions induced by a proton beam impinging on an UCx target: the proton beam will be delivered by a com-mercial cyclotron with a 40 MeV maximum energy and a 0.25 mA maximum current. The RA species, extracted from the Target-Ion-Source system as a 1+ beam , will be cooled in a RFQ (radiofrequency quadrupole) beam cool-er (RFQ-BC) and purified from the isobars contaminants through a High Resolution Mass Separator (HRMS). Post-acceleration will be performed via an ECR-based charge breeder, delivering the obtained q+ RA beam to a being built CW RFQ and to the being upgraded superconducting (sc) linac ALPI (up to 10 MeV/A for a mass-to-charge ratio A/q=7).  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL015  
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TUPAL027 Design of Multi-MW Rapid Cycling Synchrotron for Accelerator Driven Transmutation System lattice, extraction, proton, synchrotron 1057
 
  • Y. Fuwa
    Kyoto ICR, Uji, Kyoto, Japan
  • N. Amemiya
    Kyoto University, Kyoto, Japan
  • Y. Ishi, Y. Kuriyama, T. Uesugi
    Kyoto University, Research Reactor Institute, Osaka, Japan
 
  For the practical application of Accelerator Driven System (ADS) that reduces the harmfulness of radioactive waste by transmutation, we are studying the development of a compact accelerator using a synchrotron as an accelerator capable of supplying a stable proton beam to a nuclear reactor. In this plan, we aim to realize down-sizing and high reliability by adopting an alternating high temperature superconducting magnet and a high repetition synchrotron applying resonant beam extraction. In this presentation we report the basic design of the optical system and beam acceleration sequence of this synchrotron.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL027  
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TUPAL029 Harmonictron cavity, proton, operation, synchrotron 1063
 
  • Y. Mori
    Kyoto University, Research Reactor Institute, Osaka, Japan
  • H. Arima, N. Ikeda, Y. Yonemura
    Kyushu University, Department of Applied Quantum Physics and Nuclear Engineering, Fukuoka, Japan
  • Y. Waga
    Kyushu University, Hakozaki, Japan
 
  The possibility of high intensity hadron/lepton accelerator based on a vertical scaling FFAG with harmonic number jump acceleration, named "Harmonictron", has been proposed. The presentation gives a design example of the Harmonictron for accelerating protons from 50 MeV to 500 MeV for generation intense secondary particles such as muon, neutron etc.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL029  
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TUPAL030 Improvement of RF Capture with Multi-Turn H Injection in KURRI FFAG Synchrotron injection, proton, scattering, closed-orbit 1066
 
  • T. Uesugi, Y. Fuwa, Y. Ishi, Y. Kuriyama, Y. Mori, H. Okita
    Kyoto University, Research Reactor Institute, Osaka, Japan
 
  In the KURRI FFAG synchrotron, charge-exchanging multi-turn injection is adopted with a stripping foil located on the closed orbit of injection energy. No injection bump orbit system is used and the beam escapes from the foil according to the closed-orbit shift by acceleration. The particles hit the foil many times and the emittance grows up during the injection. In this paper, the capture efficiencies are studied with different rf process, including adiabatic capture.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL030  
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TUPAL076 Result of the First Muon Acceleration with Radio Frequency Quadrupole rfq, experiment, simulation, target 1190
 
  • R. Kitamura
    University of Tokyo, Tokyo, Japan
  • S. Bae, B. Kim
    SNU, Seoul, Republic of Korea
  • Y. Fukao, K. Futatsukawa, N. Kawamura, T. Mibe, Y. Miyake, M. Otani, T. Yamazaki
    KEK, Tsukuba, Japan
  • K. Hasegawa, Y. Kondo, T. Morishita
    JAEA/J-PARC, Tokai-mura, Japan
  • H. Iinuma, Y. Nakazawa
    Ibaraki University, Ibaraki, Japan
  • G.P. Razuvaev
    Budker INP & NSU, Novosibirsk, Russia
  • N. Saito
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • Y. Sue
    Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
 
  Funding: This work is supported by JSPS KAKENHI Grant Numbers JP15H03666, JP16H03987, and JP16J07784.
J-PARC E34 experiment aims to measure the muon g-2/EDM precisely with novel techniques including the muon linear accelerator. Slow muon source by the metal foil method in order to cool the muon beam has been developed for the muon acceleration test with RF accelerator, because the muon beam derived from the proton driver was the tertiary beam and has a large emittance. The first verification test of the muon acceleration with RFQ was carried out at the muon test beam line of J-PARC MLF in October 2017. The incident surface muons were decelerated by the thin metal foil target and produced the negative muonium ions (Mu-), which is the bound stat of a positive muon and two electrons. After Mu- were extracted by a electrostatic accelerator as the injector of the RFQ, they were accelerated with RFQ to 88.6 keV. The accelerated Mu- were identified by the momentum selection with the bending magnet after the RFQ, and the measurement of the Time-Of-Flight. Accelerated Mu- were easily distinguished from penetrated positive muons by the difference of the polarity. The latest analysis result of the world's first muon acceleration with RFQ will be reported in this paper.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL076  
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TUZGBF3 Betatron Core Slow Extraction at CNAO betatron, extraction, synchrotron, cavity 1237
 
  • L. Falbo, E. Bressi, S. Foglio, C. Priano
    CNAO Foundation, Milan, Italy
 
  CNAO is the only Italian hadrontherapy facility able to treat tumors with beams of protons and carbon ions. Beam is extracted with a momentum selection scheme in which beam enters the third order resonance driven by a betatron core. When irradiating a tumor, it is thought as divided in the longitudinal plane in several slices while each slice is divided in the transverse plane in several spots called voxels. Considering the dose uniformity that can be obtained during extraction, the machine must extract an average intensity related to the voxel that requires less dose. Therefore during a treatment, for some slices, a technique is needed to lower the extracted beam intensity with respect to the nominal one. A way to guarantee the correct average intensity according to the treatment planning requirements, is to introduce a mechanical filter (a degrader) that reduces the intensity of the accelerated particles. However this method used in the first treatments at CNAO showed some disadvantages and it has been replaced by what has been called the "dynamic betatron" method. The paper shows the implementations and the advantages of this method in the CNAO treatments.  
slides icon Slides TUZGBF3 [2.151 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUZGBF3  
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TUPMK012 Acceleration of Charged Particles by Own Field in a Non-Stationary One-Dimensional Stream interface, ECR, electron, operation 1516
 
  • A.S. Chikhachev
    Allrussian Electrotechnical Institute, Moskow, Russia
 
  The behavior of a non-stationary stream of the charged particles interacting with own field is studied. For the description the integral of the movement received in works * ** - Meshchersky's integral is used. The additional integral of the movement - interfaced to Meshchersky's integral, necessary for completely self-agreed description of a stream of the particles interacting with own field is constructed. The system of the equations reducing a problem to the solution of system of the ordinary differential equations is removed. Private decisions for potential, density of particles and density of current are provided. Earlier the problem was studied in work ***.
* Mestschersky J. Astronomische Nachrichten, 1893, T.132, N3153, p. 9.
** Nestschersky ibid, 1902, T.159, N3807, p. 15.
*** Chikhachev A.S., Technical Phisics, 2014, vol 59, N 4, pp 487-493.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMK012  
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TUPML003 Design of an L-band Accelerating Structure for the Argonne Wakefield Accelerator Facility Witness Beam Line Energy Upgrade linac, impedance, coupling, quadrupole 1533
 
  • J.H. Shao, M.E. Conde, D.S. Doran, J.F. Power
    ANL, Argonne, Illinois, USA
  • C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
 
  The Argonne Wakefield Accelerator (AWA) facility has been devoting much effort to the fundamental R&D of two-beam acceleration (TBA) technology with two parallel L-band beam lines. Beginning from the 70 MeV drive beam line, the high frequency (C-band and above) rf power is extracted from the beam by a decelerating structure (a.k.a. power extractor), transferred to an accelerating structure in the witness beam line, and used to accelerate the 15 MeV main beam. These high frequency accelerating structures usually have a small aperture to obtain high gradient and high efficiency, making it difficult for the low energy main beam to pass. To address this issue, one proposal is to increase the main beam energy to above 30 MeV by replacing the current witness linac. A 9-cell 𝜋-mode L-band standing-wave accelerating structure has therefore been designed to meet the high shunt impedance and low cost requirements. In addition, the single-feed coupling cell has been optimized with additional symmetrical ports to eliminate field distortion. The detailed design of the new accelerating structure will be presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML003  
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TUPML005 Study of a Dielectric Disk Structure for Short Pulse Two-Beam Acceleration impedance, collider, beam-loading, linear-collider 1539
 
  • J.H. Shao, M.E. Conde, D.S. Doran, J.F. Power
    ANL, Argonne, Illinois, USA
  • C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
 
  Argonne Flexible Linear Collider (AFLC), a proposed 3 TeV electron-positron linear collider based on two-beam acceleration (TBA) scheme, applies a short pulse length (∼20 ns) to obtain a high accelerating gradient (267 MV/m) and a compact footprint (∼18 km). The baseline design of the main accelerator section adopts 26 GHz K-band traveling-wave dielectric-loaded accelerators (DLA) with an rf to beam efficiency 𝜂𝑟𝑓 −𝑏𝑒𝑎𝑚 of 27%. Recently, an alternative structure which is similar to a metallic disk-loaded one but with dielectric disks, noted as dielectric disk accelerator (DDA), has been investigated and optimized, leading to ∼45% improvement in 𝜂𝑟𝑓 −𝑏𝑒𝑎𝑚. To demonstrate the key technologies, an X-band prototype structure has been designed and will be tested at Argonne Wakefield Accelerator (AWA) facility with a 300 MW metallic power extractor. Detailed comparison between K-band DLA and DDA for AFLC main accelerator as well as the preliminary design of the X-band DDA prototype will be presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML005  
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TUPML007 Short Pulse High Power RF Generation with an X-Band Dielectric Power Extractor experiment, simulation, linear-collider, collider 1546
 
  • J.H. Shao, M.E. Conde, D.S. Doran, W. Gai, W. Liu, N.R. Neveu, J.F. Power, C. Whiteford, E.E. Wisniewski, L.M. Zheng
    ANL, Argonne, Illinois, USA
  • C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
 
  Short pulse high power rf generation is one of the key technologies for the Argonne Flexible Linear Collider (AFLC), a proposed 3 TeV electron-positron linear collider based on two-beam acceleration (TBA) scheme. Compared with metallic power extractors, dielectric structures have the potential to achieve lower fabrication cost and to withstand higher gradient. Recently, an X-band dielectric power extractor (a.k.a, DPETS) has been developed at the Argonne Wakefield Accelerator (AWA) facility and achieved 105 MW output power when driven by a high charge 8-bunch train separated by 770 ps. The design, the cold test measurement, the preliminary high power test results, and the structure inspection will be presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML007  
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TUPML036 ALEGRO, the Advanced LinEar collider study GROup collider, plasma, laser, linear-collider 1619
 
  • P. Muggli
    MPI, Muenchen, Germany
  • B. Cros
    CNRS LPGP Univ Paris Sud, Orsay, France
 
  We briefly describe activities of ALEGRO, the Advanced LinEar collider study GROup.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML036  
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TUPML041 Two-Stage Laser-Driven Plasma Acceleration With External Injection for EuPRAXIA plasma, electron, laser, wakefield 1634
 
  • E.N. Svystun, R.W. Aßmann, U. Dorda, A. Ferran Pousa, T. Heinemann, B. Marchetti, P.A. Walker, M.K. Weikum, J. Zhu
    DESY, Hamburg, Germany
  • A. Ferran Pousa, T. Heinemann, A. Martinez de la Ossa
    University of Hamburg, Hamburg, Germany
  • T. Heinemann
    USTRAT/SUPA, Glasgow, United Kingdom
 
  The EuPRAXIA (European Particle Research Accelerator with eXcellence In Applications) project aims at producing a conceptual design for the worldwide plasma-based accelerator facility, capable of delivering multi-GeV electron beams with high quality. This accelerator facility will be used for various user applications such as compact X-ray sources for medical imaging and high-energy physics detector tests. EuPRAXIA explores different approaches to plasma acceleration techniques. Laser-driven plasma wakefield acceleration with external injection of an RF-generated electron beam is one of the basic research directions of EuPRAXIA. We present studies of electron beam acceleration to GeV energies by a two-stage laser wakefield acceleration with external injection from an RF accelerator. Electron beam injection, acceleration and extraction from the plasma, using particle-in-cell simulations, are investigated.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML041  
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TUPML045 Segmented Terahertz Driven Device for Electron Acceleration electron, laser, linac, controls 1642
 
  • D. Zhang
    DESY, Hamburg, Germany
  • A-L. Calendron, H. Cankaya, M. Fakhari, A. Fallahi, Y. Hua, N.H. Matlis, X. Wu, L.E. Zapata
    CFEL, Hamburg, Germany
  • M. Hemmer, F.X. Kärtner
    Deutsches Elektronen Synchrotron (DESY) and Center for Free Electron Science (CFEL), Hamburg, Germany
  • F.X. Kärtner
    MIT, Cambridge, Massachusetts, USA
 
  Funding: ERC Synergy Grant AXSIS (609920), Deutsche Forschungsgemeinschaft (SPP1840 SOLSTICE and CUI EXC1074), and Gordon and Betty Moore foundation (ACHIP GBMF4744)
We present a segmented THz based device (STEAM) capable of performing multiple high-field operations on the 6D-phase-space of ultrashort electron bunches. Using only a few microjoules of single-cycle THz radiation, we have shown record THz-based acceleration of >30 keV of an incoming 55keV electron beam, with a peak acceleration field gradient of around 70 MV/m that is comparable with that from a conventional RF accelerator. It can be scaled up to GV/m gradients that can accelerate electrons into the MeV regime. At the same time, the STEAM device can also manipulate the electrons that show high focusing gradient (2 kT/m), compression of electron bunches down to 100 fs and streaking gradient of 140 µrad/fs, which offers temporal profile characterizations with resolution below 10 fs. The STEAM device can be fabricated with regular mechanical machining tools and supports real-time switching between different modes of operation. It paves the way for the development of THz-based compact electron guns, accelerators, ultrafast electron diffractometers and Free-Electron Lasers.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML045  
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TUPML047 Optimisation of High Transformer Ratio Plasma Wakefield Acceleration at PITZ plasma, wakefield, laser, electron 1648
 
  • G. Loisch, P. Boonpornprasert, J.D. Good, M. Groß, H. Huck, M. Krasilnikov, O. Lishilin, A. Oppelt, Y. Renier, F. Stephan
    DESY Zeuthen, Zeuthen, Germany
  • R. Brinkmann, A. Martinez de la Ossa, J. Osterhoff
    DESY, Hamburg, Germany
  • F.J. Grüner
    CFEL, Hamburg, Germany
  • F.J. Grüner, A. Martinez de la Ossa
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
 
  The transformer ratio, the ratio between maximum accelerating field and maximum decelerating field in the driving bunch of a plasma wakefield accelerator (PWFA), is one of the key aspects of this acceleration scheme. It not only defines the maximum possible energy gain of the PWFA but it is also connected to the maximum percentage of energy that can be extracted from the driver, which is a limiting factor for the efficiency of the accelerator. Since in linear wakefield theory a transformer ratio of 2 cannot be exceeded with symmetrical drive bunches, any ratio above 2 is considered high. After the first demonstration of high transformer ratio acceleration in a plasma wakefield at PITZ, the photoinjector test facility at DESY, Zeuthen site, limiting aspects of the transformer ratio are under investigation. This includes e.g. the occurrence of bunch instabilities, like the transverse two stream instability, or deviations of the experimentally achieved bunch shapes from the ideal.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML047  
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TUPML064 Staged Two Beam Acceleration Beam Line Design for the AWA Facility kicker, experiment, gun, laser 1688
 
  • N.R. Neveu
    IIT, Chicago, Illinois, USA
  • W. Gai, C.-J. Jing, J.G. Power
    ANL, Argonne, Illinois, USA
  • C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • L.K. Spentzouris
    Illinois Institute of Technology, Chicago, Illinois, USA
 
  Funding: This work is funded by the DOE Office of Science, grant no. DE-SC0015479, and contract No. DE-AC02- 06CH11357.
Two beam acceleration is a candidate for future high energy physics machines and FEL user facilities. This scheme consists of two independent electron beam lines operating synchronously. High-charge, 70 MeV drive bunch trains are injected from the RF photo-injector into decelerating structures to generate a few hundred of MW of RF power. This RF power is transferred through an RF waveguide to accelerating structures that are used to accelerate the witness beam. Staging refers to the sequential acceleration (energy gain) in two or more structures on the witness beam line. A kicker was incorporated on the drive beam line to accomplish a modular design so that each accelerating structure can be independently powered by a separate drive beam. Simulations were performed in OPAL-T to model the two beam lines. Beam sizes at the center of the structures was minimized to ensure good charge transmission. The resulting design will be the basis for proof of principle experiments that will take place at the Argonne Wakefield Accelerator (AWA) facility.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML064  
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TUPML079 A Start to End Simulation of the Laser Plasma Wakefield Acceleration Experiment at ESCULAP plasma, electron, laser, wakefield 1731
 
  • K. Wang, C. Bruni, K. Cassou, V. Chaumat, N. Delerue, D. Douillet, S. Jenzer, V. Kubytskyi, P. Lepercq, H. Purwar
    LAL, Orsay, France
  • E. Baynard, M. Pittman
    CLUPS, Orsay, France
  • J. Demailly, O. Guilbaud, S. Kazamias, B. Lucas, G. Maynard, O. Neveu, D. Ros
    CNRS LPGP Univ Paris Sud, Orsay, France
  • D. Garzella
    CEA, Gif-sur-Yvette, France
  • R. Prazeres
    CLIO/ELISE/LCP, Orsay, France
 
  We present a start to end (s2e) simulation of the Laserplasma Wake Field Accelerator (LPWA) foreseen as the ESCULAP project. We use a photo injector to produce a 5 MeV 10 pC electron bunch with a duration of 1 ps RMS, it is boosted to 10 MeV by a S-band cavity and then compressed to 74 fs RMS (30 fs FWHM) by a magnetic compression chicane (dogleg). After the dogleg, a quadrupole doublet and a triplet are utilized to match the Twiss parameters before injecting into the subsequent plasma wakefield. A 40 TW laser is used to excite plasma wakefield in the 10 cm plasma cell. An optimized configuration has been determined yielding at the plasma exit an electron beam at 180 MeV with energy spread of 4.2%, an angular divergence of 0.6 mrad and a duration of 4 fs.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML079  
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WEPAL022 Operating Experience of Water Cooling System in the J-PARC LINAC and RCS linac, diagnostics, klystron, DTL 2203
 
  • K. Suganuma, K. Fujirai, M. Kinsho, P.K. Saha, Y. Yamazaki
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
 
  The cooling system for the J-PARC LINAC and RCS uses a total of 25 circulation pumps to cool the accelerator devices. In February 2017, we experienced damage of circulation pumps due to low flow rate, and started the development of an abnormality detection system concentrating on the vibration measurements of the circulation pumps. In this report, the vibration measurement results of the coolant circulation pumps and the development status of abnormality detection through multivariate analysis using vibration values are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL022  
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THPAF042 Improvement of the Longitudinal Beam Transfer from PS to SPS at CERN cavity, emittance, controls, proton 3060
 
  • A. Lasheen, H. Damerau, J. Repond, M. Schwarz, E.N. Shaposhnikova
    CERN, Geneva, Switzerland
 
  The beam transfer from the Proton Synchrotron (PS) to the Super Proton Synchrotron (SPS) at CERN is a critical process for the production of beams for the Large Hadron Collider (LHC). A bunch-to-bucket transfer is performed with the main drawback that the rf frequency in the SPS (200 MHz) is five times higher than the one in the PS (40 MHz). The PS bunches are therefore shortened non-adiabatically before extraction by applying a fast rf voltage increase (bunch rotation) to fit them into the short rf buckets in the SPS. However, particles with large amplitude of synchrotron oscillations in the PS longitudinal phase space are not properly captured in the SPS. They contribute to losses at the injection plateau and at the start of acceleration in the SPS. In this contribution, we present measurements and simulations performed to identify the source of the uncaptured particles. The tails of the particle distribution were characterized by applying longitudinal shaving during acceleration. Furthermore, the rotated bunch distribution was improved by linearizing the rf voltage using a higher-harmonic rf cavity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF042  
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THPAF077 Ion-optical Measurements at CRYRING@ESR during Commissioning MMI, injection, simulation, closed-orbit 3161
 
  • O. Geithner, Z. Andelkovic, M. Bai, A. Bräuning-Demian, V. Chetvertkova, O. Chorniy, C. Dimopoulou, W. Geithner, O.E. Gorda, F. Herfurth, M. Lestinsky, S.A. Litvinov, S. Reimann, A. Reiter, M. Sapinski, R. Singh, T. Stöhlker, G. Vorobjev, U. Weinrich
    GSI, Darmstadt, Germany
  • A. Källberg
    Stockholm University, Stockholm, Sweden
 
  CRYRING@ESR is a heavy ion storage ring, which can cool and decelerate highly charged ions down to a few 100 keV/u. It has been relocated from Sweden to GSI, downstream of the experimental storage ring (ESR), within the FAIR project. The ring will be used as a test facility for FAIR technologies as well as for physics experiments with slow exotic ion beams for several FAIR collaborations: SPARC, BioMat, FLAIR and NUSTAR. CRYRING@ESR is in its commissioning phase since summer 2016. Several ion-optical measurements such as tunes, tune diagram, dispersion, chromaticity and orbit response matrix were performed at the ring. The measurements will be used for several purposes such as improvement of the theoretical model, closed orbit control and correction of unacceptable misalignments, calibration coefficients and field errors.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF077  
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THPAK034 Practical Betatron Tune Behavior During Acceleration in Scaling FFAG Rings at KURNS booster, betatron, proton, extraction 3287
 
  • Y. Ishi, Y. Fuwa, Y. Kuriyama, Y. Mori, H. Okita, T. Uesugi
    Kyoto University, Research Reactor Institute, Osaka, Japan
  • J.-B. Lagrange
    Imperial College of Science and Technology, Department of Physics, London, United Kingdom
 
  In scaling FFAG* accelerators, ideally, betatron tunes are fixed for each closed orbit concerned with the certain beam energy. Therefore, they should not vary during the acceleration. However, it is not the case since practical implementations of the magnetic field can not provide perfect scaling conditions. There are two types of radial scaling FFAG ring at Kyoto University Research Reactor Institute: one has no return yokes so called 'yoke free type' adopted by MAIN RING which has a large tune variations causing non negligible beam losses; the other has return yokes and filed clamps adopted by BOOSTER RING which has smaller tune variations compared with MAIN RING. We report the tune measurements and calculations based on 3-d magnetic field calculations about these two types of ring and discuss the scaling conditions in FFAG accelerators.
FFAG* : FFAG stands for fixed filed alternating gradient. It describes one the focusing scheme in the circular accelerator.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK034  
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THPAK065 Application of Transverse-to-Longitudinal Phase-Space-Exchanged Beam Produced from a Nano-Structure Photocathode to a Soft X-Ray Free-Electron Laser cathode, simulation, quadrupole, laser 3379
 
  • A. Lueangaramwong, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • G. Andonian
    RadiaBeam, Santa Monica, California, USA
  • P. Piot
    Fermilab, Batavia, Illinois, USA
 
  Nano-structured cathodes can form transversely modulated beams which can be subsequently converted to temporally modulated beam via a transverse-to-longitudinal phase space-exchanging beamline. We demonstrate via numerical simulation the generation of transversely modulated beam at the nm scale and investigate the corresponding enhancement in a soft-X-ray SASE free-electron laser. Our study is supported by start-to-end simulation combining WARP, IMPACT-T and GENESIS(FEL process) and focuses on the optimization of the beamline to preserve initial modulation at the nanometer level. We also discuss the scaling of the concept to shorter-wavelengths.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK065  
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THPAK075 Simulation of Particle Interactions in a High Intensity Radio-Frequency Quadrupole for Molecular Hydrogen Ions rfq, proton, simulation, electron 3405
 
  • M.J. Easton, H.P. Li, Y.R. Lu, Z. Wang
    PKU, Beijing, People's Republic of China
  • J. Qiang
    LBNL, Berkeley, California, USA
 
  High-intensity deuteron accelerators run the risk of deuteron-deuteron interactions leading to activation. For this reason, in the commissioning phase, a molecular hydrogen ion (H2+) beam is often used as a model for the deuteron beam without the radiation risk. However, composite ions are susceptible to particle interactions that do not affect single ions, such as stripping of electrons and charge exchange. Such interactions affect the beam dynamics results, and may lead to production of secondary particles, which in high-intensity beams may cause damage to the accelerator and reduce the quality of the beam. In order to understand these effects, we have modified the IMPACT-T particle tracking code to include particle interactions during the tracking simulation through a high-intensity continuous-wave (CW) radio-frequency quadrupole (RFQ). This code is also designed to be easily extensible to other interactions, such as collisions or break-up of heavier ions. Preliminary results and possibilities for future development will be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK075  
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THPAL004 Research and Development of RF System for SC200 Cyclotron cavity, LLRF, cyclotron, simulation 3616
 
  • G. Chen, C. Chao, G. Liu, X.Y. Long, Z. Peng, Y. Song, Y.S. Wang, C.S. Wei, M. Xu, Q. Yang, X. Zhang, Y. Zhao
    ASIPP, Hefei, People's Republic of China
  • L. Calabretta, A.C. Caruso
    INFN/LNS, Catania, Italy
  • O. Karamyshev, G.A. Karamysheva, N.A. Morozov, E. Samsonov, G. Shirkov
    JINR, Dubna, Moscow Region, Russia
 
  A 200MeV compact isochronous superconducting cyclotron, named SC200, for proton therapy is under development by collaboration of ASIPP (Hefei, China) and JINR (Dubna, Russia). The radio frequency (RF) system as one of most significant subsystems in cyclotron consists of acceleration cavity, low level RF, RF source and transmission network. SC200 has two cavities connected in the centre, which are operated at 91.5 MHz with second harmonic. To meet the required acceleration voltage, the cavities have been carefully designed with comprised choices between several aspects, such as Q factor, mechanic stability and so on. The low-level RF (LLRF) system has been implemented by using the FPGA to achieve the significant accelerating voltage with an amplitude stability of <0.2% and a phase stability of < 0.1 degree. The cavity and LLRF system have been tested outside of cyclotron, the results will be presented. For future, the commissioning of whole RF system will be started after the assembly of SC200 at the end of 2019.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL004  
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THPAL033 Measurement of the Internal Dark Current in a High Gradient Accelerator Structure at 17 GHz multipactoring, electron, experiment, simulation 3705
 
  • H. Xu, M.A. Shapiro, R.J. Temkin
    MIT/PSFC, Cambridge, Massachusetts, USA
 
  Funding: Work supported by the U.S. Department of Energy, Office of High Energy Physics, under Grant No. DE-SC0015566
We report a study of internal dark current generation by multipactor inside a 17 GHz single cell standing wave disk-loaded waveguide accelerator structure. The multipactor takes place on the side wall of the central cell, driven by the local rf electric and magnetic fields. Theory indicates that a resonant multipactor mode with two rf cycles can be excited near 45 MV/m gradient and a single rf cycle multipactor mode near 60 MV/m. The accelerator structure had two thin slits opened on the side wall of the central cell to directly extract and measure the internal dark current. The dark current was measured as a function of the gradient up to a gradient of 70 MV/m. The experimental results agreed well with theory, showing the two predicted multipactor modes. To further study the effect of the central cell side wall surface properties on the structure performance, we prepared and tested a second structure with the central cell side wall coated with a layer of diamond-like carbon. The comparison of the results showed that the coating reduced the internal dark current and thus enhanced the structure performance considerably.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL033  
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THPMF081 Intrinsic Emittance of Single Crystal Cathodes photon, electron, cathode, emittance 4263
 
  • S.S. Karkare, H.A. Padmore
    LBNL, Berkeley, California, USA
  • G. Adhikari, W.A. Schroeder
    UIC, Chicago, Illinois, USA
 
  The transverse momentum of electrons is conserved during photoemission from atomically ordered surfaces of single crystal materials. Photocathodes used in all photoinjectors today have disordered surfaces and do not exploit this phenomenon. Recently, using this conservation of transverse momentum, significant reduction in intrinsic emittance was demonstrated from the (111) surface of silver*. Here, we present measurements of transverse momentum distributions of electrons photoemitted from the ordered surfaces of Ag and Cu single crystals at several photon energies. These measurements will help in understanding the photoemission process and show how band-structure and the conservation of transverse momentum can be used to obtain further reduction in intrinsic emittance from photocathodes.
*Karkare et al., Phys. Rev. Lett. 118, 164802 (2017)
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF081  
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THPMK048 The Design and Construction of a Novel Dual-Mode Dual-Frequency Linac Design operation, impedance, cavity, resonance 4391
 
  • M.H. Nasr, S.G. Tantawi
    SLAC, Menlo Park, California, USA
 
  One promising approach in boosting accelerators efficiency is dual-mode simultaneous operation. In our work, the topic of dual-mode acceleration is studied from a wider perspective with new approaches and tools. We present a new type of accelerator structures that operates simultaneously with two modes and two frequencies. The frequencies are not constrained to be harmonically related, but rather have a common sub-harmonic. These designs will utilize a newly developed parallel-feeding network that feeds each individual accelerating cell independently using a distributed feeding network. As a result, the design problem converges to a single-cell design with identical cells. The cells are designed for maximum efficiency using new geometrical optimization that utilizes nonuniform rational B-spline (NURBS) with a series of control points. We will present a study on the topic for S-band simultaneous operation with C-band or X-band.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK048  
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THPMK087 Conceptual Design of the RF System for the Storage Ring and Linac of the New Light Source in Thailand cavity, storage-ring, linac, operation 4505
 
  • N. Juntong, T. Chanwattana, K. Kittimanapun, T. Pulampong, P. Sunwong
    SLRI, Nakhon Ratchasima, Thailand
 
  The new light source facility in Thailand will be a ring-based light source with the circumference of approximately 300m and an electron energy of 3GeV. The target beam emittance is below 1.0 nm·rad with a maximum beam current of 300mA. The injector utilizes a full energy C-band linac with a photocathode RF electron gun. The storage ring RF system is based on a 500MHz frequency. The EU-HOM damped cavity and the new SPring-8 design TM020 cavity is the choice of the storage ring cavity. The RF power unit for storage ring can either be a high-power klystron feeding all RF cavities or a combination of low power IOTs or solid-state amplifiers feeding each cavity. The high gradient C-band structure is considered as the main accelerating structure for linac. The RF power system for linac will base on klystron and a modular modulator. Details of RF systems options for this new light source project will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK087  
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THPMK147 Measurement of Slice-Emittance of Electron Bunch Using RF Transverse Deflector emittance, injection, experiment, electron 4648
 
  • T. Sasaki, Y. Nakazato, M. Washio
    Waseda University, Tokyo, Japan
  • Y. Koshiba
    RISE, Tokyo, Japan
  • K. Sakaue
    Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
 
  We have been studying a compact electron accelerator based on an S-band Cs-Te photocathode rf electron gun at Waseda University. We are applying this high quality electron beam to soft X-ray generation, coherent THz wave generation and pulse radiolysis experiment. In these applications, longitudinal parameters of the electron beam are important. Thus, we developed the RF deflecting cavity which can directly convert longitudinal distribution of the beam to transverse with high temporal resolution, and succeeded in measuring longitudinal profile of an electron beam from the RF gun. Encouraged by these successful results, we started to measure slice emittance. Slice emittance would be very useful for improving the RF electron gun cavity. Therefore, we tried to measure the slice emittance of the electron beam by applying the Q-scan method to deflected beam by RF deflecting cavity. In this conference, we will report the principle, experimental results of the slice emittance measurement, and future prospects.
C. Vaccarezza et al., "Slice emittance measurements at SPARC photoinjector with a RF deflector", Proc. of EPAC08, Genoa, Italy
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK147  
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THPML011 Possibilities for Fabricating Polymer Dielectric Laser Accelerator Structures with Additive Manufacturing laser, site, electron, lattice 4671
 
  • E.I. Simakov, R.D. Gilbertson, M.J. Herman, G. Pilania, D.Y. Shchegolkov, E.M. Walker, E. Weis
    LANL, Los Alamos, New Mexico, USA
  • R.J. England, K.P. Wootton
    SLAC, Menlo Park, California, USA
 
  Funding: Los Alamos National Laboratory LDRD Program
We present results of recent studies of new materials designed for the additive manufacturing of accelerating structures for dielectric laser accelerators (DLAs). Demonstration of a stand-alone practical DLA requires innovation in design and fabrication of efficient laser accelerator structures and couplers. Many complicated three-dimensional structures for laser acceleration (such as a long woodpile structure with couplers) are difficult to manufacture with conventional microfabrication technologies. LANL has a large effort focused on developing new materials and techniques for additive manufacturing. The materials for DLA structures must have high dielectric constant (larger than 4), low loss in the infrared regime, high laser damage threshold, and be able to withstand the electron beam damage. This presentation will discuss the development of novel infrared dielectric materials that are of interest for laser acceleration and are compatible with additive manufacturing, as well as recent advances in additive manufacturing of dielectric woodpile structures using a Nanoscribe direct laser-writing 3D printer.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML011  
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THPML012 Simulations and Measurements of the Wakefield Loading Effect in Argonne Wakefield Accelerator Beamline wakefield, experiment, linac, higher-order-mode 4675
 
  • J. Upadhyay, E.I. Simakov
    LANL, Los Alamos, New Mexico, USA
  • M.E. Conde, Q. Gao, N.R. Neveu, J.G. Power, J.H. Shao, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
  • N.R. Neveu
    IIT, Chicago, Illinois, USA
 
  A beam driven acceleration experiment in a photonic band gap (PBG) structure is planned at Argonne wakefied accelerator (AWA) facility at Argonne National Laboratory. We plan to pass a high charge (drive) beam through a travelling wave 11.7 GHz PBG structure and generate a wakefield. This wakefield will be probed by a low charge (witness) beam to demonstrate wakefield acceleration and deceleration. The drive and witness bunches will be accelerated to above 60 MeV in the main accelerator at AWA which has frequency of 1.3 GHz. The charges used in this experiment could be as high as 20 nC. To measure the exclusive effect of PBG the structure on acceleration and deceleration of the witness bunch we have to exclude the effect of beam loading of the main AWA accelerator structure. To understand the wakefield effect in AWA, we conducted an experiment where we passed the high charge (10 nC) beam through the accelerator structure which was followed by a 2 nC witness beam separated by 4 wavelength. The energy of witness beam was measured in the presence and absence of the drive beam. The beam loading was observed and quantified. The results of this work will be presented in the conference.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML012  
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THPML013 Demonstration of the Wakefield Acceleration in an 11.7 GHz Photonic Band Gap Accelerator Structure experiment, wakefield, electron, higher-order-mode 4678
 
  • J. Upadhyay, E.I. Simakov
    LANL, Los Alamos, New Mexico, USA
  • M.E. Conde, Q. Gao, N.R. Neveu, J.G. Power, J.H. Shao, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
 
  We plan to conduct a beam driven acceleration experiment in a photonic band gap (PBG) accelerator structure operating at 11.7 GHz at Argonne Wakefield Accelerator (AWA) facility. For the experiment, the PBG structure will be excited by a high charge (up to 10 nC) electron bunch, and a second smaller charge witness bunch will be accelerated. Because the PBG structure was fabricated with electroforming, the AWA beamline includes a Be window placed before the PBG structure that protects the cathode from contamination due to possible outgassing from the electroformed copper. The diameter of the Be window is 9 mm and the beam tube diameter of the PBG structure is 6.4 mm. The size of the high charge electron beam on Be window has to be minimized to minimize scattering. The parameters of the beamline had to be adjusted to achieve good propagation of the beam. An OPAL simulation for the AWA beamline was performed for 1, 5, and 10 nC beams. The beam size was experimentally measured at different positions in the beamline for different charges to verify simulations. Finally, the high charge electron beam was passed through the PBG structure and acceleration of the witness bunch was measured  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML013  
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THPML014 A Metamaterial Wagon Wheel Structure for Wakefield Acceleration by Reversed Cherenkov Radiation wakefield, experiment, simulation, electron 4681
 
  • X.Y. Lu, I. Mastovsky, M.A. Shapiro, R.J. Temkin
    MIT/PSFC, Cambridge, Massachusetts, USA
  • M.E. Conde, C.-J. Jing, J.G. Power, J.H. Shao, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
 
  Funding: U.S. Department of Energy, Office of Science, Office of High Energy Physics under Award Number DE-SC0015566 and the U.S. Department of Energy Office of Science under Contract No. DE-AC02-06CH11357
We present the design and experimental operation on an X-band metamaterial (MTM) wagon wheel structure for wakefield acceleration. The structure was designed and fabricated at MIT, and tested at the Argonne Wakefield Accelerator (AWA) laboratory at Argonne National Lab. The MTM wagon wheel structure is an all-metal periodic structure at 11.4 GHz. The fundamental TM mode has a negative group velocity, so when an electron beam travels through, energy is extracted from the beam by reversed Cherenkov radiation, which was verified in the experiment. Single bunches up to 45 nC were sent through the structure with a beam aperture of 6 mm and generated microwave power up to 25 MW in a 2 ns pulse, in agreement with both the analytical wakefield theory and the numerical CST simulations. Two bunches with a total charge of 85 nC generated 80 MW of microwave power. The structure is scalable to a power extractor of over 1 GW by increasing the structure length from 8 cm to 22 cm.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML014  
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THPML024 Monoenergetic Beam Generated by Laser Accelerator at Peking University laser, proton, quadrupole, experiment 4702
 
  • K. Zhu, J.E. Chen, Y.X. Geng, C. Li, D.Y. Li, Q. Liao, C. Lin, H.Y. Lu, W.J. Ma, Y.R. Shou, Wu,M.J. Wu, X.H. Xu, X.Q. Yan, J.Q. Yu, Y.Y. Zhao, J.G. Zhu
    PKU, Beijing, People's Republic of China
 
  An ultrahigh-intensity laser incident on a target sets up a very strong electrostatic field exceeding 100 GV/m, it will few orders magnitude shrink down the traditional radio frequency accelerators. Whereas, to build a real accelerator for routine operation, many scientific and technical challenges for laser acceleration need to overcome before they could be applied to these applications. Recently A laser accelerator− Compact Laser Plasma Accelerator (CLAPA) is being built with a beam line to deliver proton beam with the energy of 1~15MeV, energy spread of ¡À1% and 107-8 protons per pulse. The very high current proton beam is accelerated in laser ultrathin-foil interaction and transported by a beam line consisting of the electric quadruple and analyzing magnets. It makes sure the good beam qualities such as energy spread, charge, repeatability and availability of different energy, which means that for the first laser acceleration becomes a real laser accelerator. With the development of high-rep rate PW laser technology, we can now envision a compact beam therapeutic machine of cancer treatment in the near future soon.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML024  
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THPML031 Collective Acceleration of Laser Plasma in Non-stationary and Non-uniform Magnetic Field plasma, laser, target, experiment 4716
 
  • A.A. Isaev, C.I. Kozlovskij, E.D. Vovchenko
    MEPhI, Moscow, Russia
 
  This paper presents the new experimental results concerning acceleration of deuterium ions extracted from laser plasma in the rapid-growing nonuniform magnetic field in order to initiate the nuclear reactions D(d, n)3He and Т (d,n)4He. In order to obtain plasma a laser that generates in Q-switched mode the pulses of infrared radiation (λ = 1.06 μm) with the energy W ≤ 0.85 J and duration of ≈10 ns. In the present study, the velocity of a bunch of a laser plasma at a magnetic field induction rate of 3-108 T/s was experimentally measured, and angular distributions of accelerated particle fluxes were measured in the range from 0 to 30 degrees. The maximum and mean ion velocities were determined by the time-of-flight technique. The proposed system allows the generation of neutrons, including possibly thermonuclear ones, on counterflows using two similar magnetic accelerators located coaxially, facing each other. In this case the problem related to degradation of solid neutron-generating targets is resolved. There also occurs a possibility of fast accumulated running time of packed solid targets at using of deuteron-tritium laser targets.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML031  
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THPML032 Using Deep Reinforcement Learning for Designing Sub-Relativistic Electron Linac network, electron, linac, cavity 4720
 
  • Shin, S.W. Shin, J.-S. Chai, M. Ghergherehchi
    SKKU, Suwon, Republic of Korea
 
  Generally, when designing an accelerator device, the design is based on the experience and knowledge of the designer. Most of the design process proceeds by chang-ing the parameters and looking at the trends and then determining the optimal values. This process is time-consuming and tedious. In order to efficiently perform this tedious design process, a method using an optimization algorithm is used. Recently, many people started to get interested in the algorithm used in AlphaGo, which became famous when it won the professional Go player developed by google The algorithm used in AlphaGo is an algorithm called reinforcement learning that learns how to get optimal reward in various states by moving around a solution space that the agent has not told beforehand. In this paper, we will discuss about designing an particle accelerator by applying Deep Q-network algorithm which is one kind of deep learning reinforcement learning.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML032  
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THPML042 Integrating the Lorentz Force Law for Highly-Relativistic Particle-in-Cell Simulations plasma, laser, simulation, radiation 4734
 
  • A.V. Higuera, J.R. Cary
    Tech-X, Boulder, Colorado, USA
  • J.R. Cary
    CIPS, Boulder, Colorado, USA
 
  Funding: This work is supported by the DOE under Grants No. DE-SC0011617 and DE-SC0012444, and by DOE/NSF Grant No. DE-SC0012584
Integrating the Relativistic Lorentz Force Law for plasma simulations is an area of current research (*, **, ***). In particular, recent research indicates that interaction with highly-relativistic laser fields is particularly problematic for current integration techniques (****). Here is presented a special-purpose integrator yielding improved accuracy for highly-relativistic laser-particle interactions. This integrator has been implemented in the particle-in-cell code VSim, and the authors present an accuracy and performance comparison with several particle push methods.
* http://aip.scitation.org/doi/abs/10.1063/1.4979989
** https://arxiv.org/abs/1702.04486
*** https://arxiv.org/abs/1710.09164
**** http://aip.scitation.org/doi/abs/10.1063/1.4905523
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML042  
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THPML043 Optimization of Dielectric Laser-Driven Accelerators laser, electron, simulation, plasma 4737
 
  • C.P. Welsch, M.G. Ibison, Y. Wei
    The University of Liverpool, Liverpool, United Kingdom
  • M.G. Ibison, Y. Wei, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • J.D.A. Smith
    TXUK, Warrington, United Kingdom
  • G.X. Xia
    UMAN, Manchester, United Kingdom
 
  Funding: This project has received funding from the European Union's Seventh Framework Programme for research, technological development and demonstration under grant agreement no 289191.
Dielectric laser-driven accelerators (DLAs) utilizing large electric field from commercial laser system to accelerate particles with high gradients in the range of GV/m have the potential to realize a first particle accelerator ‘on a chip'. Dual-grating structures are one of the candidates for DLAs. They can be mass-produced using available nanofabrication techniques due to their simpler structural geometry compared to other types of DLAs. Apart from the results from optimization studies that indicate the best structures, this contribution also introduces two new schemes that can help further improve the accelerating efficiency in dual-grating structures. One is to introduce a Bragg reflector that can boost the accelerating field in the channel, the other applies pulse-front-tilt operation for a laser beam to help extend the interaction length.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML043  
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THPML051 Electron Acceleration by Plasma Wave in the Presence of a Transversely Propagated Laser with Magnetic Field electron, plasma, laser, wakefield 4749
 
  • M. Yadav, S. C. Sharma
    DELTECH, New Delhi, India
  • D.N. Gupta, M. Kaur
    University of Delhi, Delhi, India
 
  It has been revealed that a relativistic plasma wave, having an extremely large electric field, may be utilized for the acceleration of plasma particles. The large accelerating field gradient driven by a plasma wave is the basic motivation behind the acceleration mechanism. Such a plasma wave can be excited by a single laser in the form wakefield in laser-plasma interactions. In this paper, we study the enhancement of electron acceleration by plasma wave in presence of a laser* propagated perpendicular to the propagation of the wake wave. Electrons trapped in the plasma wave are effectively accelerated by the additional field of the laser combined with wakefield. The additional resonance provided by the laser field contributes to the large energy gain of electrons during acceleration. The resonant enhancement of electron acceleration has been validated by single particle simulations**. The dependence of energy gain on laser intensity, laser spot size, initial electron energy, and electron trajectories have been investigated.
* G. D. Tsakiris, C. Gahn, and V. K. Tripathi, Phys. Plasmas 7, 3017 (2000)
** Maninder Kaur, and D. N. Gupta, IEEE, 45, p 2841 - 2847, (2017)
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML051  
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THPML058 Recent Results from MICE on Multiple Coulomb Scattering and Energy Loss scattering, emittance, detector, lepton 4766
 
  • P. Franchini
    University of Warwick, Coventry, United Kingdom
 
  Funding: STFC, DOE, NSF, INFN, and CHIPP
Multiple Coulomb scattering and energy loss are well known phenomena experienced by charged particles as they traverse a material. However, from recent measurements made by the MuScat collaboration, it is known that the available simulation codes (GEANT4, for example) overestimate the scattering of muons in low Z materials. This is of particular interest to the Muon Ionization Cooling Experiment* (MICE) collaboration which has the goal of measuring the reduction of the emittance of a muon beam induced by energy loss in low Z absorbers. MICE took data without magnetic field suitable for multiple scattering measurements in the autumn of 2015 with the absorber vessel filled with xenon and in the spring of 2016 using a lithium-hydride absorber. In the autumn of 2016 MICE took data with magnetic fields on and studied the energy loss of muons in a lithium-hydride absorber. These data are all compared with the Bethe-Bloch formula and with the predictions of various models, including the default GEANT4 model.
*Submitted by the MICE Speakers bureau, to be prepared and presented by a MICE member to be selected in due course
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML058  
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THPML088 Cavity Impedance Reduction Strategies During Multi Cavity Operation in the SIS100 High Intensity Hadron Synchrotron cavity, controls, emittance, resonance 4863
 
  • D. Mihailescu Stoica, D. Domont-Yankulova
    Technische Universität Darmstadt (TU Darmstadt, RMR), Darmstadt, Germany
  • D. Domont-Yankulova, H. Klingbeil
    TEMF, TU Darmstadt, Darmstadt, Germany
  • H. Klingbeil, D.E.M. Lens
    GSI, Darmstadt, Germany
 
  Funding: Supported by GSI Helmholtzzentrum für Schwerionenforschung GmbH
The planned SIS100 heavy ion synchrotron at the GSI Helmholtzzentrum für Schwerionenforschung will possess twenty ferrite accelerating cavities in its final stage of extension. As at injection and at flat top during slow extraction of the planned acceleration cycles the RF voltage will be relatively low, not all cavities will be active in this part of operation. It is important to analyse the impact of the inactive cavities on the overall RF voltage and subsequently their implication on the longitudinal particle dynamics. Classical approaches for reducing the beam impedance consist of active detuning of the cavities to pre-described parking frequencies. The fact that two out of ten buckets have to stay empty in all SIS100 scenarios is of particular interest as additional frequency components appear in the excitatory beam current, which have to be considered when the cavity is detuned. Therefore multi-cavity particle tracking simulations, consisting of twenty cavities and their attached LLRF control systems, are carried out in order to analyse different possibilities to minimize the impact on the beam dynamics and emittance growth.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML088  
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THPML091 Design of a High Gradient 60 GHz Dielectric Accelerating Structure experiment, electromagnetic-fields, electron, simulation 4873
 
  • D.Z. Cao, D. Dan, W. Gai, C.-X. Tang, H. Zha
    TUB, Beijing, People's Republic of China
 
  RF breakdown are the main limitation for the application of high gradient structures. Higher frequencies and shorter pulse length benefit the design of accelerating structure for the breakdown threshold of surface field is Es=f1/2 τ-1/4. Power source which generates very short V-band pulse with nearly hundred megawatt is now available. The paper presents the analysis of a V-band dielectric acceleration structure and power source. Future plan about RF transmission and power coupling of the whole structure will be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML091  
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THPML120 Development of Coating Technique for Superconducting Multilayered Structure site, cavity, target, experiment 4954
 
  • R. Ito, T. Nagata
    ULVAC, Inc, Chiba, Japan
  • H. Hayano, T. Kubo, T. Saeki
    KEK, Ibaraki, Japan
  • H. Ito
    Sokendai, Ibaraki, Japan
  • Y. Iwashita, R. Katayama
    Kyoto ICR, Uji, Kyoto, Japan
  • H. Oikawa
    Utsunomiya University, Utsunomiya, Japan
 
  In order to increase the maximum acceleration gradient of SRF cavities, S-I-S (superconductor-insulator-superconductor) multilayered structure theory has been proposed. We focused on NbN which has a higher superconducting transition temperature than Nb. Firstly, we researched the optimal deposition condition for N2 gas reactive sputtering of NbN by using in-house inter-back type DC magnetron sputtering equipment. The critical condition for a thin film with strong crystalline orientation of NbN was identified. The superconducting transition temperature of the NbN thin film, which were coated under the best condition, was over 14 K. Secondly, we tried making S-I-S multilayered samples that was composed of NbN/SiO2/Nb substrate. The coating condition for the NbN layer was determined based on the research results in a single layer. The SiO2 layer was deposited with a film thickness of 30 nm that was theoretically expected to be effective as barrier layer. We applied O2 gas reactive AC magnetron sputtering for coating. In this article, the detailed results of the NbN single layer and multilayer film depositions are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML120  
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FRXGBF1 Re-Acceleration of Ultra Cold Muon in J-PARC Muon Facility linac, rfq, experiment, emittance 5041
 
  • Y. Kondo, K. Hasegawa, T. Morishita
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • S. Bae, H. Choi, S. Choi, B. Kim, H.S. Ko
    SNU, Seoul, Republic of Korea
  • Y. Fukao, K. Futatsukawa, N. Kawamura, T. Mibe, Y. Miyake, M. Otani, K. Shimomura, T. Yamazaki, M. Yoshida
    KEK, Tsukuba, Japan
  • N. Hayashizaki
    RLNR, Tokyo, Japan
  • T. Iijima, Y. Sue
    Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
  • H. Iinuma, Y. Nakazawa
    Ibaraki University, Ibaraki, Japan
  • K. Ishida
    RIKEN Nishina Center, Wako, Japan
  • Y. Iwashita
    Kyoto ICR, Uji, Kyoto, Japan
  • Y. Iwata
    NIRS, Chiba-shi, Japan
  • R. Kitamura
    University of Tokyo, Tokyo, Japan
  • S. Li
    The University of Tokyo, Graduate School of Science, Tokyo, Japan
  • G.P. Razuvaev
    Budker INP & NSU, Novosibirsk, Russia
  • N. Saito
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
 
  Funding: This work is supported by JSPS KAKENHI Grant Numbers JP15H03666, JP16H03987, and JP16J07784.
J-PARC is developing the reacceleration system of the ultra slow (30 meV) muon (USM) obtained by two-photon laser resonant ionization of muonium atoms. The muon beam thus obtained has low emittance, meeting the requirement for the g-2/EDM experiment. J-PARC E34 experiment aims to measure the muon anomalous magnetic moment (g-2) with a precision of 0.1 ppm and search for EDM with a sensitivity to 10-21 e cm. The USM's are accelerated to 212 MeV by using a muon dedicated linac to be a ultra cold muon beam. The muon LINAC consists of an RFQ, a inter-digital H-mode DTL, disk and washer coupled cell structures, and disk loaded structures. The ultra-cold muons will have an extremely small transverse momentum spread of 0.1% with a normalized transverse emittance of around 1.5 pi mm-mrad. Proof of the slow muon acceleration scheme is an essential step to realize the world first muon linac. In October 2017, we have succeeded to accelerate slow negative muoniums generated using a simpler muonium source to 89 keV. In this talk, present design of the muon linac and the result of the world first muon acceleration experiment are reported.
 
slides icon Slides FRXGBF1 [8.378 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-FRXGBF1  
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