WEPVA —  Posters Wednesday 3   (17-May-17   16:00—18:00)
Paper Title Page
WEPVA001 Electron Injector for Multi-Stage Laser-Driven Plasma Accelerators 3244
 
  • B. Cros, T. Audet, P. Lee, G. Maynard
    CNRS LPGP Univ Paris Sud, Orsay, France
  • A. Chancé, O. Delferrière, A. Mosnier
    CEA/DSM/IRFU, France
  • N. Delerue
    LAL, Orsay, France
  • S. Dobosz-Dufrénoy, A. Maitrallain, P. Monot
    CEA, Gif-sur-Yvette, France
  • J. Schwindling
    CEA/IRFU, Gif-sur-Yvette, France
  • A. Specka
    LLR, Palaiseau, France
 
  Funding: LAbex PALM, Labex P2IO, Triangle de la Physique, ANR grant Equipex CILEX APOLLON, EU H2020 research and innovation programme under grant agreement No. 653782 EUPRAXIA.
An electron injector in the 50-200 MeV range, based on laser wakefield acceleration, is studied in the context of multi-stage laser plasma acceleration. Test experiments carried out at the UHI100 laser facility show that electron bunches in the 100 MeV range, generated by ionization-induced injection mechanism, and accelerated by laser driven wakefield in a mm-scale length plasma can be transported using a magnetic line and precisely analysed. A comparison with simulation results provides insights on electron dynamics and indicates ways to optimize the injector.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA001  
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WEPVA002 Simulations of DLA Grating Structures in the Frequency Domain 3247
SUSPSIK027   use link to see paper's listing under its alternate paper code  
 
  • T. Egenolf, O. Boine-Frankenheim, U. Niedermayer
    TEMF, TU Darmstadt, Darmstadt, Germany
  • O. Boine-Frankenheim
    GSI, Darmstadt, Germany
 
  Dielectric laser accelerators (DLA) driven by ultrashort laser pulses can reach orders of magnitude larger gradients than contemporary RF electron accelerators. A new implemented field solver based on the finite element method in the frequency domain allows the calculation of the structure constant, i.e. the ratio of energy gain to laser peak amplitude. We present the maximization of this ratio as a parameter study looking at a single grating period only. Based on this optimized shape the entire design of a beta-matched grating is completed in an iterative process. The period length of a beta-matched grating increases due to the increasing velocity of the electron when a subrelativistic beam is accelerated. The determination of the optimal length of each grating period thus requires the knowledge of the energy gain within all so far crossed periods. Furthermore, we outline to reverse the excitation in the presented solver for beam coupling impedance calculations and an estimation of the beam loading intensity limit.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA002  
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WEPVA003 Designing a Dielectric Laser Accelerator on a Chip 3250
 
  • U. Niedermayer, O. Boine-Frankenheim, T. Egenolf
    TEMF, TU Darmstadt, Darmstadt, Germany
 
  Funding: This work is funded by the Gordon and Betty Moore Foundation (Grant GBMF4744 to Stanford) and the German Federal Ministry of Science and Education (Grant FKZ:05K16RDB).
Dielectric Laser Acceleration (DLA) achieves gradients of more than 1GeV/m, which are among the highest in non-plasma accelerators. The long-term goal of the ACHIP collaboration* is to provide relativistic (>1 MeV) electrons by means of a laser driven microchip accelerator. Examples of slightly resonant dielectric structures showing gradients in the range of 70% of the incident laser field (1 GV/m) for electrons with β=0.32 and 200% for β=0.91 are presented. We demonstrate the bunching and acceleration of low energy electrons in dedicated ballistic buncher and velocity matched grating structures. However, the design gradient of 500 MeV/m leads to rapid defocusing. Therefore we present a scheme to bunch the beam in stages, which does not only reduce the energy spread, but also the transverse defocusing. The designs are made with a dedicated homemade 6D particle tracking code.
* https://achip.stanford.edu
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA003  
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WEPVA004 Simulation of an Electromagnetic Field Excitation by a THz-pulse and Acceleration of an Electron Bunch in a Dielectric-loaded AXSIS Linac 3253
 
  • K. Galaydych, R.W. Aßmann, U. Dorda, B. Marchetti, G. Vashchenko, I. Zagorodnov
    DESY, Hamburg, Germany
 
  Funding: The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013) / ERC Grant Agreement n. 609920
The Attosecond X-ray Science: Imaging and Spectroscopy (AXSIS) experiment at DESY will use a dielectric loaded waveguide to accelerate electron bunches up to 15 MeV. Such a linac will be powered by a narrowband multicycle THz-pulse with a central frequency of 300 GHz. In this paper we focus on the reflection of the excited field at a pinhole, on the optimization of the bunch injection time and on the bunch dynamics in the acceleration process. The linac excitation by the THz-pulse and the bunch acceleration in the excited field are investigated using CST and ECHO simulations.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA004  
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WEPVA005 Simulation of a Many Period Dielectric Grating-based Electron Accelerator 3256
 
  • W. Kuropka, R.W. Aßmann, U. Dorda, F. Mayet
    DESY, Hamburg, Germany
  • W. Kuropka, F. Mayet
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
 
  Funding: GBMF - Gordon and Betty Moore Foundation
Dielectric laser driven particle accelerators have become a research area of major interest due to the high acceleration gradients achievable. Those are mainly attributed to the high damage thresholds of dielectrics at optical frequencies. Simulations of these structures are usually computed with Particle-In-Cell (PIC) codes. Their accuracy and self consistency comes with a major drawback of high computation costs. Computation of structures consistent of hundreds to thousands of periods are only viable with High Performance Computing clusters. In this proceeding a compromise of CST* PIC simulations combined with a transfer function model is presented to simulate relativistic electron accelerators for particle energies up to the GeV regime or higher. In addition a simplified example accelerator design is investigated and the required electron bunch parameters from a sub-relativistic source are computed.
*CST - Computer Simulation Technology, available from www.
cst.com.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA005  
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WEPVA006 A Concept for Phase-Synchronous Acceleration of Microbunch Trains in DLA Structures at SINBAD 3260
 
  • F. Mayet, R.W. Aßmann, J. Bödewadt, R. Brinkmann, U. Dorda, W. Kuropka, C. Lechner, B. Marchetti, J. Zhu
    DESY, Hamburg, Germany
  • W. Kuropka, F. Mayet
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • J. Zhu
    University of Hamburg, Hamburg, Germany
 
  Funding: GBMF - Gordon and Betty Moore Foundation
The concept of dielectric laser accelerators (DLA) has gained increasing attention in accelerator research, because of the high achievable acceleration gradients (~GeV/m). This is due to the high damage threshold of dielectrics at optical frequencies. In the context of the Accelerator on a Chip International Program (ACHIP) we plan to inject electron bunches into a laser-illuminated dielectric grating structure. At a laser wavelength of 2 micro-meter the accelerating bucket is <1.5 fs. This requires both ultra-short bunches and highly stable laser to electron phase. We propose a scheme with intrinsic laser to electron synchronization and describe a possible implementation at the SINBAD facility (DESY). Prior to injection, the electron bunch is conditioned by interaction with an external laser field in an undulator. This generates a sinusoidal energy modulation that is transformed into periodic microbunches in a subsequent chicane. The phase synchronization is achieved by driving both the modulation process and the DLA with the same laser pulse. This allows scanning the electron bunch to laser phase and will show the dependence of the acceleration process on this delay.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA006  
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WEPVA007 Simulations and Plans for a Dielectric Laser Acceleration Experiment at SINBAD 3264
 
  • F. Mayet, R.W. Aßmann, U. Dorda, W. Kuropka, B. Marchetti, J. Zhu
    DESY, Hamburg, Germany
  • W. Kuropka, F. Mayet
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • J. Zhu
    University of Hamburg, Hamburg, Germany
 
  Funding: GBMF - Gordon and Betty Moore Foundation
In this work we present the outline of an experimental setup for dielectric laser acceleration of relativistic electron bunches produced by the ARES linac under construction at the SINBAD facility (DESY Hamburg). The experiment will be performed as part of the Accelerator on a Chip International Program (ACHIP), funded by the Gordon and Betty Moore Foundation. At SINBAD we plan to test the acceleration of already pre-accelerated relativistic electron bunches in a laser-illuminated dielectric grating structure. In addition to the conceptual layout of the experiment we present first start-to-end simulation results for different ARES working points. The simulations are performed using a combination of the well known particle tracking code ASTRA and the self-consistent particle in cell code VSim.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA007  
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WEPVA008 Beam Dynamics in THz Dielectric Loaded Waveguides for the AXSIS Project 3268
 
  • T. Vinatier, R.W. Aßmann, U. Dorda, B. Marchetti
    DESY, Hamburg, Germany
  • F. Lemery
    CFEL, Hamburg, Germany
 
  In this paper, we investigate with ASTRA simulations the beam dynamics in dielectric-loaded waveguides driven by THz pulses, used as linac structure for the AXSIS project. We show that the bunch properties at the linac exit are very sensitive to the phase velocity of the THz pulse and are limited by the strong phase slippage of the bunch respective to it. We also show that some margins for instabilities of the injection phase into the linac structure are allowed. We finally demonstrate that the bunch properties are optimized when low frequencies (< 300 GHz) are used inside the linac, and that the longitudinal focal point can be put several tens of cm away from the linac exit thanks to ballistic bunching. However, a strong asymmetry in the bunch transverse sizes remains for which a solution is still to be found.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA008  
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WEPVA011 Development of a Laser Driven Dielectric Accelerator for Radiobiology Research 3272
 
  • K. Koyama, M. Yoshida
    KEK, Ibaraki, Japan
  • Z. Chen, H. Okamoto
    The University of Tokyo, Tokyo, Japan
  • M. Uesaka
    The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
 
  Funding: This work was supported by KAKENHI, (Grant-in-Aid for Scientific Research) Grant Number 15H03595 and partly supported by NIMS Nanofabrication Platform in Nanotechnology Platform Project sponsored by the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan.
A laser-driven dielectric accelerator below 1 MeV is under development for applying a sub-micron size electron-beam to radiobiological research. Simulations of the electric field and electron trajectories in the proximity of the dielectric structure (transmission grating) were performed in order to fix parameters of the demonstration experiment. Serious deflection of electron beam towards the grating limited the injection phase as well as the height from the structure. The energy gain of 50-keV electron was estimated to be 1 keV in 30-micron length at the optimum condition. Transmission gratings for the experiment were fabricated by using facilities of the NIMS Nanofabrication Platform. In addition to the acceleration experiment using the simple grating, a resonator type accelerator structure was designed for exciting the acceleration field by a moderately small laser.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA011  
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WEPVA012 Laser Proton Accelerator with Improved Repeatability at Peking University 3275
SUSPSIK028   use link to see paper's listing under its alternate paper code  
 
  • Y.R. Shou
    Peking University, School of Physics, Beijing, People's Republic of China
  • Y.X. Geng, C. Li, L.R.F. Li, Q. Liao, C. Lin, H.Y. Lu, W.J. Ma, P. Wang, M. Wu, X. Xu, X.Q. Yan, Y.Y. Zhao, J.G. Zhu
    PKU, Beijing, People's Republic of China
 
  Funding: National Basic Research Program of China (Grant No. 2013CBA01502), National Natural Science Foundation of China (Grants No. 11575011) and National Grand Instrument Project (2012YQ030142).
The repeatability of laser proton accelerator is mainly limited by laser plasma interaction, laser target coupling and laser parameter variation. In our recent experiments performed on the Compact Laser Plasma Accelerator at Peking University, gain of proton beams with improved repeatability is demonstrated. In order to control the laser plasma interaction in pre-plasma, cross polarized-wave (XPW) generation technique is employed to provide a laser pulse with a good contrast of 10-10. A semi-automatic laser and target alignment system with a sensitivity of few micrometers is employed. The repetition rate of the laser proton accelerator is improved to the level of 0.1 Hz which is beneficial to decrease laser parameter variation. The shot-to-shot variation of proton energies is about 9% for a level of confidence of 0.95.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA012  
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WEPVA013 Small Size Neutron Generators with Laser Induced Plasma and Electron Conductivity Suppressed by Magnetic Field 3278
 
  • V.I. Rashchikov, S.M. Polozovpresenter, A.E. Shikanov
    MEPhI, Moscow, Russia
 
  Coaxial neutron tubes generators with transverse dimension less than 0.1 m are discussed. Laser plasma containing deuterons is created at the anode by a focused laser beam. Deuterons from plasma are accelerated by pulse voltage and produces neutrons on cylindrical cathode symmetrically surrounding the anode. Magnetic field was used to suppress knock on parasitic electron current in the accelerating gap. Computer simulation with code SUMA* was fulfilled to investigate output neutron flow dependence on laser produced plasma density, magnetic fields and pulse voltage shapes and amplitudes, cathode and anode materials. The results obtained are in a good agreement with conducted experiments on diode with electron conductivity suppressed by magnetic field produced by permanent magnets**.
*V.I.Rashchikov, Problems of Atomic Science and Technology. Series: Nuclear Physics Investigations, 10(18), 50 (1990).
**A.E.Shikanov et al., Atomic energy, 119, No.4, 258 (2016).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA013  
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WEPVA014 Status of R&D on New Superconducting Injector Linac for Nuclotron-NICA 3282
 
  • G.V. Trubnikov, A.V. Butenko, N. Emelianov, A.O. Sidorin, E. Syresin
    JINR, Dubna, Moscow Region, Russia
  • T.A. Bakhareva, M. Gusarova, T. Kulevoy, S.V. Matsievskiy, S.M. Polozovpresenter, A.V. Samoshin, N.P. Sobenin, D.V. Surkov, K.V. Taletskiy, S.E. Toporkov, V. Zvyagintsev
    MEPhI, Moscow, Russia
  • A.A. Bakinowskaya, A.A. Marysheva, V.S. Petrakovsky, I.L. Pobol, A.I. Pokrovsky, D.A. Shparla, S.V. Yurevich, V.G. Zaleski
    Physical-Technical Institute of the National Academy of Sciences of Belarus, Minsk, Belarus
  • M.A. Baturitski, S.A. Maksimenko
    INP BSU, Minsk, Belarus
  • S.E. Demyanov
    Scientific-Practical Materials Research Centre of the National Academy of Sciences of Belarus, Minsk, Belarus
  • V.A. Karpovich
    BSU, Minsk, Belarus
  • T. Kulevoy, S.M. Polozovpresenter
    ITEP, Moscow, Russia
  • A.A. Kurayev, V.V. Matbeenko, A.O. Rak
    Belarus State University of Informatics and Radioelectronics (BSUIR), Minsk, Belarus
  • V.N. Rodionova
    Belarussian State University, Scientific Research Institute of Nuclear Problems, Minsk, Belarus
  • A.O. Sidorin
    Saint Petersburg State University, Saint Petersburg, Russia
  • V. Zvyagintsev
    TRIUMF, Vancouver, Canada
 
  The new collaboration of JINR, NRNU MEPhI, INP BSU, PTI NASB, BSUIR and SPMRC NASB starts in 2015 the project of linac-injector design in 2015. The goal of new linac is to accelerate protons up to 25 MeV (and up to 50 MeV at the second stage) and light ions to ~7.5 MeV/u for Nuclotron-NICA injection. Current results of the linac general design and development, beam dynamics simulations, SC cavities design and SRF technology development are presented in this report.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA014  
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WEPVA016 Dielectric Laser Accelerator Investigation, Setup Substrate Manufacturing and Investigation of Effects of Laser Induced Electromigration RF Cavity Breakdown Influences 3286
 
  • M. Hamberg, M. Jacewicz, J. Oegrenpresenter
    Uppsala University, Uppsala, Sweden
  • M. Karlsson, E. Vargas Catalan
    Uppsala University, Department of Engineering Sciences, Uppsala, Sweden
  • M. Kuittinen, I. Vartiainen
    UEF, Joensuu, Finland
 
  Funding: I thank Stockholm Uppsala centre for FEL research for funding.
Dielectric laser acceleration (DLA) where the high electric fields in lasers are used to accelerate electrons next to nanofabricated dielectric structures has recently been proven in proof of concept studies. In this paper I describe investigations setup and substrate manufacturing. Additionally we describe using the setup for evaluating RF structure breakdown due to laser induced electromigration occurences.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA016  
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WEPVA017 Efficiency Enhancement Induced by a Precursor Electron Bunch in Quasi-Phase Matched Direct Laser Acceleration 3289
SUSPSIK030   use link to see paper's listing under its alternate paper code  
 
  • C.-Y. Hsieh, S.-H. Chen
    NCU, Chung Li, Taiwan
  • I. Jovanovic
    NERS-UM, Ann Arbor, Michigan, USA
  • M.W. Lin
    National Tsing-Hua University (NTHU), Hsinchu, Taiwan
 
  Funding: This work is supported by the Ministry of Science and Technology in Taiwan by Grant MOST 104-2112-M-008-013-MY3 and the United States Defense Threat Reduction Agency through contract HDTRA1-11-1-0009
Direct laser acceleration (DLA) of an electron bunch can be achieved by utilizing the axial field of a well-guided, radially polarized laser pulse in a density-modulated plasma waveguide*. However, the ponderomotive force of a TW-class laser pulse excites a plasma wave that can generate a defocusing electrostatic field, which significantly deteriorates the transverse properties of the injected electron witness bunch**. To improve the quality of the accelerated witness bunch, an additional leading electron bunch, termed as a precursor, is introduced to generate ion-focusing force to effectively confine the trailing witness bunch. We conducted three-dimensional particle-in-cell simulations to investigate the effect of bunch charge, transverse size of the precursor, and the axial separation between the precursor and the witness bunch on the efficacy of DLA. Results indicate that the transverse properties of the witness bunch can be maintained and the overall DLA efficiency can be improved, when a favorable ion-focusing force is provided by the precursor.
* A. G. York, et al., Phys. Rev. Lett. 100, 195001 (2008).
** M. -W. Lin et al., Phys. Plasmas 21, 093109 (2014).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA017  
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WEPVA018 Drive-Witness Acceleration Scheme Based on Corrugated Dielectric mm-Scale Capillary 3292
 
  • K. Lekomtsev, S.T. Boogert, P. Karataev, A. Lyapin
    JAI, Egham, Surrey, United Kingdom
  • A. Aryshev, M. Shevelev, N. Terunuma, J. Urakawa
    KEK, Ibaraki, Japan
  • A.A. Tishchenko
    MEPhI, Moscow, Russia
 
  Funding: This project has received funding from the European Union Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 655179.
In this paper, we investigate a corrugated mm-scale capillary as a compact accelerating structure in a drive-witness acceleration scheme, and suggest a methodology to measure acceleration of a witness bunch. Two typical measurements and the energy gain in a witness bunch as a function of the distance between bunches are discussed. A corrugated capillary is considered as an accelerator/decelerator with an adjustable wakefield pattern depending on a transverse beam position.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA018  
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WEPVA019 Group Velocity Matching in Dielectric-Lined Waveguides and its Role in Electron-THz Interaction 3296
SUSPSIK031   use link to see paper's listing under its alternate paper code  
 
  • A.L. Healy, G. Burt
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • D.M. Graham
    The University of Manchester, The Photon Science Institute, Manchester, United Kingdom
  • S.P. Jamison
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
 
  Terahertz(THz)-driven dielectric-lined waveguides have applications in electron manipulation, particularly acceleration, as the use of dielectric allows for phase velocities below the speed of light. However matching a single frequency to the correct velocity does not maximise electron-THz interaction; waveguide dispersion typically results in an unmatched group velocity and so the pulse envelope of a short THz pulse changes along the length of the structure. This reduces field amplitude and therefore accelerating gradient as the envelope propagates at a different velocity to the electron. Presented here is an analysis of the effect of waveguide dispersion on THz-electron interaction and its influence on structure dimensions and choice of THz pulse generation. This effect on net acceleration is demonstrated via an example of a structure excited by a single-cycle THz pulse, with a comparison of multi-cycle, lower intensity THz pulses on net acceleration.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA019  
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WEPVA020 Dual-Grating Dielectric Accelerators Driven by A Pulse-Front-Tilted Laser 3299
 
  • Y. Wei, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • M.M. Dehler, E. Ferrari, N. Hiller, R. Ischebeck
    PSI, Villigen PSI, Switzerland
  • J.D.A. Smith
    TXUK, Warrington, United Kingdom
  • C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • G.X. Xia
    UMAN, Manchester, United Kingdom
 
  Dual-grating Dielectric Laser-driven Accelerators (DLAs) are considered to be one of the most promising technologies to miniaturize future particle accelerators. Accelerating gradients in the GV/m range seem accessible and 690 MV/m has been demonstrated in fused silica structures. However, the increase in beam energy is limited by the short interaction length between the laser pulses and the electron bunch. In this contribution, a pulse-front-tilt operation for a laser beam is studied to extend the interaction length, resulting in a greater energy gain for a dual-grating DLA. The VSIM code is used to compare this new scheme with the commonly used approach of a normally incident laser beam and advantages are summarized.
[1]T. Plettner, et al., Phys. Rev. ST Accel. Beams 9, 111301 (2006)
[2]K. P. Wootton, et al., Opt. Lett., 41, 2696 (2016).
[3]E. A. Peralta, et al., Nature 503, 91 (2013)
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA020  
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WEPVA021 Phase Space Manipulation of Sub-Picosecond Electron Bunches Using Dielectric Wakefield Structures 3302
SUSPSIK032   use link to see paper's listing under its alternate paper code  
 
  • T.H. Pacey, G.X. Xia
    UMAN, Manchester, United Kingdom
  • D.J. Dunning, Y.M. Saveliev
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
 
  Dielectric lined waveguides have drawn interest due to their application as high gradient accelerating structures, in both externally driven and wakefield schemes. We present simulation studies of sub-picosecond electron bunches interacting with dielectric structures in the self-wake regime. The parameter space for a tunable, sub-millimeter aperture, terahertz frequency structure is investigated. The potential application as a longitudinal phase space dechirper is demonstrated, with specific application to CLARA at Daresbury Laboratory. The impact of transverse effects is considered and minimised. The resulting FEL output is simulated.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA021  
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WEPVA022 RECENT TWO-BEAM ACCELERATION ACTIVITIES AT ARGONNE WAKEFIELD ACCELERATOR FACILITY 3305
 
  • J.H. Shao, S.P. Antipov, M.E. Conde, W. Gai, Q. Gao, G. Ha, W. Liu, N.R. Neveupresenter, J.G. Power, Y.R. Wang, E.E. Wisniewski, L.M. Zheng
    ANL, Argonne, Illinois, USA
  • C.-J. Jing, J.Q. Qiu
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • J. Shi, D. Wang
    TUB, Beijing, People's Republic of China
 
  The Two-Beam Acceleration (TBA) is a modified approach to the structure-based wakefield acceleration which may meet the luminosity, efficiency, and cost requirement of a future linear collider. Recently, various TBA experiments have been carried out at the Argonne Wakefield Accelerator Facility (AWA). With X-band metallic power extractors and accelerators, a 70 MeV/m average accelerating gradient has been demonstrated in two stages while a 150 MeV/m gradient as well as 300 MW extracted power have been achieved in a single stage. In addition, low cost K-band dielectric power extractor and accelerator have also been developed. The preliminary results show power extraction of 55 MW and an average accelerating gradient of 28 MeV/m.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA022  
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WEPVA023 Performance of the PS Injection Kicker System Short Circuit Mode Upgrade for Operation with 2 GeV LIU Beams 3308
 
  • T. Kramer, W. Bartmann, J.C.C.M. Borburgh, L. Ducimetière, L.M.C. Feliciano, A. Ferrero Colomo, B. Goddard, L. Sermeus
    CERN, Geneva, Switzerland
 
  In the framework of the LHC Injector Upgrade (LIU) project an upgrade of the existing PS proton injection kicker system for 2 GeV operation is in progress. The upgrade is based on the operation of the existing kicker system in short circuit mode. This paper briefly reviews the deployed modifications to the system to obtain the specified reduction of pulse reflections unavoidably induced by such a configuration. The implementation of improvements to the magnet entry box, transmission cables and the short circuit plug with integrated LC-filter are described as well as tests and measurements during the 2016/17 annual shutdown. The impact of the residual pulse shape structure on the beam performance for the reference LIU beam is quantified. The paper concludes with a performance analysis, a comparison of measurements vs. simulations and an outlook to the remaining modifications during the next long shut down.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA023  
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WEPVA024 Design of an Inductive Adder for the FCC Injection Kicker Pulse Generator 3312
 
  • D. Woog, M.J. Barnes, L. Ducimetière, J. Holma, T. Kramerpresenter
    CERN, Geneva, Switzerland
 
  The injection system for a 100 TeV centre-of-mass collider is an important part of the Future Circular Collider (FCC) study. Due to issues with conventional kicker systems, such as self-triggering and long term availability of thyratrons and limitations of HV-cables, innovative design changes are planned for the FCC injection kicker pulse generator. An inductive adder (IA) based on semiconductor (SC) switches is a promising technology for kicker systems. Its modular design, and the possibility of an active ripple suppression are significant advantages. Since the IA is a complex device, with multiple components whose characteristics are important, a detailed design study and construction of a prototype is necessary. This paper summarizes the system requirements and constraints, and describes the main components and design challenges of the prototype IA. It outlines the results from simulations and measurements on different magnetic core materials as well as on SC switches. The paper concludes on the design choices and progress for the prototype to be built at CERN.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA024  
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WEPVA029 SIS100 Tunnel Design and Status 3316
 
  • C. Omet, J. Falenski, G. Fehrenbacher, H. Kisker, K. Konradt, A. Sokolov, P.J. Spiller
    GSI, Darmstadt, Germany
  • A. Fischer
    FAIR, Darmstadt, Germany
 
  As the FAIR project is proceeding, many of the building and tunnel designs in the meanwhile are frozen and documents are prepared for tendering. For the future FAIR driver accelerator, SIS100, the accelerator tunnel T110 comprises a 1100 m long tunnel, which has a depth of 17 m under ground. In this paper, its environmental boundary conditions, design principles and the finally chosen layout are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA029  
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WEPVA030 FAIR SIS100 - Features and Status of Realisation 3320
 
  • P.J. Spiller, U. Blell, L.H.J. Bozyk, T. Eisel, E.S. Fischer, J. Henschel, P. Hülsmann, H. Klingbeil, H.G. König, H. Kollmus, P. Kowina, J.P. Meier, A. Mierau, C. Mühle, C. Omet, D. Ondreka, V.P. Plyusnin, I. Pongrac, N. Pyka, P. Rottländer, C. Roux, J. Stadlmann, B. Streicher, St. Wilfert
    GSI, Darmstadt, Germany
 
  SIS100 is a unique heavy ion synchrotron designed for the generation of high intensity heavy ion and Proton beams. New features and solutions are implemented to enable operation with low charge state heavy ions and to minimize ionization beam loss driven by collisions with the residual gas. SIS100 aims for new frontier and world wide leading Uranium bam intensities. A huge effort is taken to stabilized the dynamics of the residual gas pressure and to suppress ion induced desorption. Fast ramped superconducting magnets have been developed and are in production with highest precision in engineering and field quality, matching the requirements from beams with high space charge. A powerful equipment with Rf stations for fast acceleration, pre- and final compression, for the generation of barrier buckets and provision of longitudinal feed-back shall allow a flexible handling of the ion bunches for the matching to various user requirements. Results obtained with FOS (first of series) devices, status of realisation and technical challenges resulting from the demanding goals, will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA030  
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WEPVA033 Conceptual Design Considerations for a 1.3 TeV Superconducting SPS (scSPS) 3323
 
  • F. Burkart, W. Bartmann, M. Benedikt, B. Goddard, A. Milanese, J.S. Schmidtpresenter
    CERN, Geneva, Switzerland
 
  The Future Circular Collider for hadrons (FCC-hh) envisaged at CERN will require a High Energy Booster as injector. One option being studied is to reuse the 6.9 km circumference tunnel of the SPS to house a fast-ramping superconducting machine. This paper presents the conceptual design considerations for this superconducting single aperture accelerator (designated scSPS) which can be used to accelerate protons to an extraction energy of 1.3 TeV, both for FCC and for fixed target beam operation in CERN's North Area. As FCC injector this accelerator has to be used in a fast cycling mode to fulfil the FCC-hh requirements concerning filling time, which impacts directly the choice of magnet technology. The reliability and availability will also play important roles in the design, and the inclusion of a fixed target capacity also has significant implications for the lattice and layout. The cell design, magnet parameters, overall layout, design of the different insertion and performance estimates for specific applications will be presented and discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA033  
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WEPVA034 ELENA - From Installation to Commissioning 3327
 
  • T. Eriksson, W. Bartmann, P. Belochitskii, L. Bojtár, H. Breuker, F. Butin, C. Carli, B. Dupuy, P. Freyermuth, L.V. Jørgensen, B. Lefort, J. Mertens, R. Ostojić, S. Pasinelli, G. Tranquille
    CERN, Geneva, Switzerland
  • W. Oelert
    Johannes Gutenberg University Mainz, Institut für Physik, Mainz, Germany
 
  ELENA (Extra Low ENergy Antiproton ring) is an upgrade project at the CERN AD (Antiproton Decelerator). The smaller ELENA ring will further decelerate 5.3 MeV antiprotons from the AD ring down to 100 keV using electron cooling to obtain good deceleration efficiency and dense beams. An increase of up to two orders of magnitude in trapping efficiency is expected at the AD experiments. This paper will report on the current status of ELENA where beam commissioning of the ring is now taking place. Phase one of the project installation has been completed with ring and injection lines in place, while phase two will finalize the project with installation of 100 keV transfer lines connecting the experiments to ELENA and is planned to take place in 2019/2020.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA034  
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WEPVA035 The PSB Operational Scenario with Longitudinal Painting Injection in the Post-LIU Era 3331
 
  • V. Forte, S.C.P. Albright, M.E. Angoletta, P. Baudrenghien, E. Benedetto, A. Blas, C. Bracco, C. Carli, A. Findlay, R. Garoby, G. Hagmann, A.M. Lombardi, B. Mikulec, M.M. Paoluzzi, J.L. Sanchez Alvarez, R. Wegner
    CERN, Geneva, Switzerland
 
  Longitudinal painting has been presented as an elegant technique to fill the longitudinal phase space at injection to the CERN PSB once it is connected with the new Linac4. Painting brings several advantages related to a more controlled longitudinal filamentation, lower peak line density and beating reduction, resulting in a smaller space-charge tune spread. This could be an advantage especially for high intensity beams (> 6·1012 protons per bunch) to limit losses on the transverse acceptance of the machine. This paper presents an overview on the possible advantages of the technique for operational and test beams, taking care of the hardware limitations and possible failure scenarios.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA035  
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WEPVA036 The LHC Injectors Upgrade (LIU) Project at CERN: Proton Injector Chain 3335
 
  • K. Hanke, J. Coupard, H. Damerau, A. Funken, B. Goddard, A.M. Lombardi, D. Manglunki, S. Mataguez, M. Meddahi, B. Mikulec, G. Rumolo, R. Scrivens, E.N. Shaposhnikova, M. Vretenar
    CERN, Geneva, Switzerland
 
  The LHC Injectors Upgrade (LIU) project at CERN aims at delivering high brightness beams required by the LHC in the high-luminosity LHC (HLLHC) era. The project comprises a new H Linac (Linac4) as well as a massive upgrade of the PS Booster, PS and SPS synchrotrons. This paper gives an update of the activities regarding the proton injector chain. We present the target beam parameters, a brief status of the upgrade work per machine and the outcome of the recent reviews. The planning for the implementation of the hardware upgrades and the re-commissioning of the complex will also be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA036  
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WEPVA037 Machine Development Studies in the CERN PS Booster, in 2016 3339
 
  • E. Benedetto, S.C.P. Albright, M.E. Angoletta, W. Bartmann, J.M. Belleman, A. Blas, M. Cieslak-Kowalska, G.P. Di Giovanni, A. Findlay, V. Forte, A. Garcia-Tabares, G. Guidoboni, S. Hancock, M. Jaussi, B. Mikulec, J.C. Molendijk, A. Oeftiger, T.L. Rijoff, F. Schmidt, P. Zisopoulospresenter
    CERN, Geneva, Switzerland
  • M. Cieslak-Kowalska
    EPFL, Lausanne, Switzerland
  • P. Zisopoulospresenter
    Uppsala University, Uppsala, Sweden
 
  The paper presents the outstanding studies performed in 2016 in preparation of the PS Booster upgrade, within the LHC Injector Upgrade project (LIU), to provide twice higher brightness and intensity to the High-Luminosity LHC. Major changes include the increase of injection and extraction energy, the implementation of a H charge-exchange injection system, the replacement of the present Main Power Supply and the deployment of a new RF system (and related Low-Level), based on the Finemet technology. Although the major improvements will be visible only after the upgrade, the present machine can already benefit of the work done, in terms of better brightness, transmission and improved reproducibility of the present operational beams. Studies address the space-charge limitations at low energy, for which a detailed optics model is needed and for which mitigation measurements are under study, and the blow-up reduction at injection in the downstream machine, for which the beams need careful preparation and transmission. Moreover they address the requirements and the reliability of new beam instrumentation and hardware that is being installed in view of LIU.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA037  
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WEPVA038 Tail Repopulation Measurements in the PSB 3343
 
  • E. Benedetto, M. Cieslak-Kowalska, P. Zisopoulospresenter
    CERN, Geneva, Switzerland
  • M. Cieslak-Kowalska
    EPFL, Lausanne, Switzerland
 
  The PS Booster (PSB) is the first circular accelerator in the LHC injector chain providing protons for the full CERN complex. Each of its four rings provides beams in a range of intensities varying from 40 e11 p/cycle to 0.8 e13 p/cycle. Low intensity beams are produced by transverse shaving, that is by scraping the tails, in order to tailor the intensity and transverse emittances. Eventually, tails repopulate and the beam profile reshapes, under the effect of space charge, which is dominant at low energy in the PS Booster. This paper describes the results of the measurements after the shaving process, where the tails are scraped but finally re-appear in the transverse profile, and it provides a first benchmark with space-charge simulations. It highlights the challenges encountered and the lessons learned, to guide the future experiments. The final outcome of these studies is the characterisation of the halo creation mechanism and the determination of the diffusion speed, important for the design of the future PS Booster scraping system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA038  
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WEPVA039 Transition Crossing in the Main Injector for PIP-II 3347
 
  • R. Ainsworth, S. Chaurizepresenter, I. Kourbanis, E.G. Stern
    Fermilab, Batavia, Illinois, USA
 
  Proton Improvement Plan-II (PIP-II) is Fermilab's plan for providing powerful, high-intensity proton beams to the laboratory's experiments. PIP II will include upgrades to the Booster, Recycler and Main Injector which will be required to accelerate 50% more beam as well as increasing the Booster repetition rate from 15 to 20 Hz. To accommodate the faster rate, the momentum separation of the slip stacking beams in the Recycler must increase which will result in in larger longitudinal emittance bunches in MI. In order to cross transition without losses, it is expected a gamma-t jump will be needed. Gamma-t jump schemes for the MI are investigated.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA039  
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WEPVA040 Design of Imaginary Transition Gamma Booster Synchrotron for the Jefferson Lab EIC (JLEIC) 3350
 
  • S.A. Bogacz
    JLab, Newport News, Virginia, USA
 
  Funding: Work has been authored by Jefferson Science Associates, LLC under Contract No. DE-AC05-06OR23177 with the U.S. Department of Energy. The U.S. Government retains a non- exclusive, world-wide license to publish or reproduce this manuscript, or allow others to do so, for U.S. Government purposes.
Baseline design of the JLEIC booster synchrotron is presented. Its aim is to inject and accumulate heavy ions and protons at 285 MeV, to accelerate them to about 7 GeV, and finally to extract them into the ion collider ring. The Figure-8 ring features two 260 deg. achromatic arcs configured with negative momentum compaction lattices, designed to avoid transition crossing for all ion species during the course of acceleration. The arc optics is based on a lightly perturbed 90 deg. FODO, with missing dipoles every fourth half-cell, where the horizontal dispersion is driven partly negative for the inward bending arc leading to negative momentum compaction. The lattice also features a specialized high dispersion injection insert optimized to facilitate the transverse phase-space painting in both planes for multi-turn ion injection. Furthermore, the lattice has been optimized to mitigate magnet error sensitivity and to ease chromaticity correction with two families of sextupoles in each plane. The booster ring is configured with super-ferric, 3 Tesla bends. We are presently launching optimization of the booster synchrotron design to operate in the extreme space-charge dominated regime.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA040  
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WEPVA041 Rematching AGS Booster Synchrotron Injection Lattice for Smaller Transverse Beam Emittances 3353
 
  • C. Liu, J. Beebe-Wang, K.A. Brown, C.J. Gardner, H. Huang, M.G. Minty, V. Schoefer, K. Zeno
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The polarized proton beam is injected into the booster via the charge-exchange (H to H+) scheme. The emittance growth due to scattering at the stripping foil is proportional to the beta functions at the foil. It was demonstrated that the current scheme of reducing the beta functions at the stripping foil preserves the emittance better, however the betatron tunes are above but very close to half integer. Due to concern of space charge and half integer in general, options of lattice designs aimed towards reducing the beta functions at the stripping foil with tunes at more favorable places are explored.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA041  
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WEPVA043 Study of the Suitability of 3D Printing for Ultra-High Vacuum Applications 3356
 
  • S. Jenzer, M. Alves, N. Deleruepresenter, A. Gonnin, D. Grasset, F. Letellier-Cohen, B. Mercier, E. Mistretta, C. Prevost
    LAL, Orsay, France
  • A. Vion
    BV Proto, Sévenans, France
  • J-P. Wilmes
    AGS Fusion, Izernore, France
 
  Funding: IN2P3/CNRS
In the recent year additive fabrication (3D printing) has revolutionized mechanical engineering by allowing the quick production of mechanical components with complex shapes. So far most of these components are made in plastic and therefore can not be used in accelerator beam pipes. We have investigated samples printed using a metal 3D printer to study their behavior under vacuum. We report on our first tests showing that such samples are vacuum compatible and comparing pumping time.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA043  
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WEPVA047 Input Signal Generation for Barrier Bucket RF Systems at GSI 3359
 
  • J. Harzheim, D. Domont-Yankulova, K. Groß, H. Klingbeil
    TEMF, TU Darmstadt, Darmstadt, Germany
  • M. Frey, H. Klingbeil
    GSI, Darmstadt, Germany
 
  At the GSI facility in Darmstadt, Germany, Barrier Bucket RF systems are currently designed for the SIS 100 synchrotron (part of the future FAIR facility) and the Experimental Storage Ring (ESR). The purpose of these systems is to provide single sine voltage pulses at the cavity gap. Due to the high requirements regarding the gap signal quality, the calculation of the pre-distorted input signal plays a major role in the system development. A procedure to generate the input signal based on the dynamic properties in the linear region of the system has been developed and tested at a prototype system. It was shown that this method is able to generate single sine gap signals of high quality in a wide voltage range. As linearity can only be assumed up to a certain magnitude, nonlinear effects limit the quality of the output signal at very high input levels. An approach to overcome this limit is to extend the input signal calculation to a nonlinear model of the system. In this contribution, the current method to calculate the required input signal is presented and experimental results at a prototype system are shown. Additionally, first results in the nonlinear region are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA047  
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WEPVA048 Particle Generation of CapaciTorr Pumps 3363
 
  • S. Lederer, L. Lilje
    DESY, Hamburg, Germany
  • E. Maccallini, P. Manini, F. Siviero
    SAES Getters S.p.A., Lainate, Italy
 
  Non Evaporable Getter pumps have been used since four decades in various scientific and industrial Ultra High and Extremely Ultra High Vacuum applications. For the majority of applications properties like high pumping speed vs. small size, powerless operation and hydrocarbon cleanliness are main aspects for the usage. In addition to this a growing number of applications nowadays also require particle free systems. In this paper we report on investigations on in-vacuum particle creation during the conditioning and activation process of CapaciTorr pumps.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA048  
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WEPVA049 Vacuum- and Bake-Out-Testbenches for the HESR at FAIR 3366
 
  • H. Jagdfeld, M. Bai, U. Bechstedt, N. Bongers, P. Chaumet, F.M. Esser, F. Jordan, F. Klehr, G. Langenberg, G. Natour, U. Pabst, D. Prasuhn, L. Semke, F. Zahariev
    FZJ, Jülich, Germany
 
  The High-Energy Storage Ring (HESR) is one part of the international Facility for Antiproton and Ion Research (FAIR) at GSI Darmstadt. Forschungszentrum Jülich (IKP and ZEA-1) is responsible for the design and development of the HESR. The HESR is designed for antiprotons and heavy ion experiments as well. Therefore the vacuum is required to be 10-11 mbar or better. To achieve this also in the curved sections, where 44 bent dipole magnets are installed, NEG coated dipole chambers will be used to reach the needed pumping speed and capacity. For activation of the NEG a bake-out system is needed. Two test benches were installed to investigate the required equipment needed to reach this low pressure: A vacuum test bench to investigate the influence of different types and quantity of vacuum pumps for the straight sections of the HESR A bake-out test bench for checking the achievable end pressure and develop the bake-out system for the NEG coated dipole chambers in the curved sections of the HESR The results of the tests and the bake-out concept including the layout of the control system and the special design of the heater jackets inside the dipoles and quadrupoles are presented.
1 Central Institute of Engineering, Electronics and Analytics- Engineering and Technology ZEA-1
2 Institute for nuclear physics
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA049  
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WEPVA050 Developments for the Injection Kicker Vacuum System of the HESR at FAIR 3369
 
  • F. Zahariev, M. Bai, N. Bongers, P. Chaumet, F.M. Esser, R. Gebel, H. Glückler, S. Hamzic, H. Jagdfeld, B. Laatsch, W. Lesmeister, L. Reifferscheidt, M. Retzlaff, L. Semke, R. Tölle
    FZJ, Jülich, Germany
  • G. Natour
    Forschungszentrum Jülich GmbH, Central Institute of Engineering, Electronics and Analytics, Jülich, Germany
 
  The Research Center Jülich has taken the leadership of a consortium being responsible for the design and manufacturing of the High-Energy Storage Ring (HESR) going to be part of FAIR. The HESR is designed both for antiprotons and for heavy ion experiments. The injection kicker system of the HESR is located directly behind the septum and consists of two pumping crosses for pumps and measurement devices as well as two vacuum tanks housing the four ferrite magnets which will be operated with 40 kV, 4kA. As well as the magnets, the adjustments frames and the electrical feedthroughs will be installed inside the tanks. Due to the large surface of the magnets the injection kicker system will be very sensitive with regard to the achievable vacuum quality that is expected to be in the order of 10-11 mbar or better. Thus the vacuum system is designed to heat up to 250°C. In order to investigate the achievable end pressure and to develop the heating system a test facility was constructed. The actual vacuum layout of the injection kicker system as well as the experimental test results will be presented and in similar the layout of the control system of the test facility will be described.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA050  
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WEPVA051 Power Converters for the ESS Warm Magnets 3372
 
  • R. Visintini, M. Cautero
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • G. Göransson, C.A. Martins, P.J. Torri
    ESS, Lund, Sweden
 
  In the framework of the Italian In-Kind Contribution (IKC) to the construction of the European Spallation Source (ESS), Elettra Sincrotrone Trieste is in charge of providing some key equipment for the accelerator. Among them, there are the magnets and the associated power converters for the Linac Warm Units (LWU), the High Energy Beam Transport (HEBT) dogleg, the Dump Line (DmpL) and the Accelerator to Target (A2T) sections of the neutron source. Magnets and their power converters are complementary parts of common systems. Their design cannot be totally separated, requiring iterations for an optimal solution that should include also power cable standardization. This work will describe the power converters' solutions adopted for the magnets of the above-mentioned sections. They comprise 4-Quadrant power converters for the correctors, compact DC power converters for the small quadrupole magnets and more powerful DC power converters for the dipole and large quadrupole magnets.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA051  
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WEPVA052 The Infrastructure for the Elettra Sincrotrone Trieste 3375
 
  • D. Zangrando, D. Baron, A. Buonanno, A. Galimberti, A. Martinolli, M. Miculin, D. Morelli
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
 
  Elettra - Sincrotrone Trieste S.C.p.A. is a multidisciplinary international laboratory, specialized in generating high quality synchrotron and free-electron laser light and applying it in materials science. The main assets of the research centre are two advanced light sources, the electron storage ring Elettra and the free-electron laser (FEL) FERMI, continuously (H24) operated supplying light of the selected colour and quality to more than 30 experimental stations. In this paper, we are giving an overview on the status of the infrastructure plants devoted to ensuring the operation of Elettra and FERMI machines. We will also analyse the systems that mostly have impacted on the performance of both accelerators and their downtime.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA052  
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WEPVA053 New Extraction Line for the Lns Cyclotron 3378
 
  • L. Calabretta, A. Calanna, G. D'Agostino, D. Rifuggiato, A.D. Russo
    INFN/LNS, Catania, Italy
  • G. D'Agostino
    Universita Degli Studi Di Catania, Catania, Italy
 
  The LNS Superconducting Cyclotron will be modified to allow the extraction by stripper of ion beams with power up to 10 kW. By choosing properly the position of the stripper foils and of the corrector magnetic channels, it is possible to convoy the trajectories of the selected representative ion beams across a new extraction channel. It is mandatory to design a new extraction line to transport these beams to the existing beam transport line. The extracted beams have an energy spread of about ±0.4%, so, the new extraction line has to compensate the correlation energy-position of the beam and to produce an achromatic waist of the beam at the common starting point of the existing transport lines. The main changes of the cyclotron will be briefly described and the performance and the features of the new extraction line will be presented too.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA053  
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WEPVA054 Study of The New Return Yoke for The Upgraded Superconducting Cyclotron of INFN-LNS 3381
 
  • A. Calanna, L. Allegra, L. Calabrettapresenter, G. Costa, G. D'Agostino, G. Gallo, D. Rifuggiato, A.D. Russo
    INFN/LNS, Catania, Italy
  • G. D'Agostino
    Universita Degli Studi Di Catania, Catania, Italy
 
  The LNS Superconducting Cyclotron (CS) has been working for 20 years making available a wide range of ions and energies. Its operational diagram is peculiar and many experiment are performed each year. In the near future a major upgrade is planned. This will allow to overcome the major limitation of the CS, which is the beam power limited at 100 W. In the new version of the CS, the extracted beam power will be increased up to a factor 100. This improvement will be reached adding a new extraction line dedicated to a specific set of light ions and energies extracted by stripping. The new design could affect the beam dynamics strongly. Indeed, the iron yoke penetrations don't respect the three folds symmetry of our cyclotron. This inhomogeneity produces unwanted field harmonics, which have to be reduced as much as possible to avoid beam precession or second order effects. Here the study accomplished to minimize the perturbation of the non-three fold field symmetry using the current sheet approximation (CSA) is presented, along with the state-of-art configuration of the updated cyclotron  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA054  
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WEPVA055 Pre Orbit Correction Based on Tunnel Level Measurement in SuperKEKB 3385
 
  • A. Morita, H. Koisopresenter, Y. Ohnishi, H. Sugimoto
    KEK, Ibaraki, Japan
 
  The SuperKEKB accelerator tunnel has about 30mm displacement in the vertical direction. From the result of optics correction simulation with the tunnel displacement, it was decided that the beamline components align against the smoothed line of the measured tunnel level in order to save the alignment cost and time. In order to compensate the large tunnel displacement, the pre orbit correction based on the tunnel level measurement is applied at the beginning of the phase-1 commissioning, and the beam circulation is achieved with the small number of magnet adjustments. We report the result of the pre orbit correction.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA055  
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WEPVA056 Development of an Induction Accelerator Cell Driver Utilizing 3.3 kV SiC-MOSFETs 3388
 
  • K. Okamura, K. Takayama
    KEK, Ibaraki, Japan
  • K. Takayama
    Sokendai, Ibaraki, Japan
 
  A novel synchrotron called an induction synchrotron (IS) was developed at KEK in 2006*. In the IS, charged particles are accelerated by pulse voltages driven by switching modulators employing high-speed semiconductor switches. As the switches are turned on and off by gate signals corresponding to the revolution frequency of the ion bunches, switching frequency reaches up to MHz order. The switching power supply (SPS) that generates bipolar pulses is one of the key technologies for the DA. The rating of SPS is roughly 2.5kV-20A-1MHz. To accomplish these requirements, we adopted 7 series connected Si-MOSFET for the switching devices of the 1st generation SPS. However it was too large and complicated for the future practical accelerator driver. Therefore we started to develop the next generation of SPS utilizing silicon carbide (SiC) devices, since they have inherently excellent properties such as high breakdown electric field high drift velocity, and high thermal conductivity**. In this paper, we describe the pulse switching test results of a prototype SiC-MOSFET and the test results of the prototype SPS.
* K. Takayama et al., Phys. Rev. Lett., 98, no.5, pp.054801(1)-054801(4) (2007).
**H. Okumura, Japanese J. Appl. Phys. vol.45, no.10A, pp. 7565-7586, Oct. 2006.
 
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WEPVA057 High-Stability Magnet Power Supplies for SuperKEKB 3391
 
  • T. Oki, T. Adachi, S. Nakamura
    KEK, Ibaraki, Japan
 
  For the SuperKEKB, over 2,000 of magnet power supplies were recycled and around 300 of power supplies were newly fabricated. The newly fabricated power supplies include high performance power supplies: the main bending/wiggler magnet power supplies and the power supplies for final-focus superconducting magnets installed around an interaction point. High power tests were performed and the results are reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA057  
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WEPVA058 Development of HOM Absorber for SuperKEKB 3394
 
  • S. Terui, T. Ishibashi, Y. Suetsugu, Y. Takeuchi, K. Watanabe
    KEK, Ibaraki, Japan
  • H. Ishizaki, A. Kimura, T. Sawhata
    Metal Technology Co. Ltd., Ibaraki, Japan
 
  Higher-order modes (HOM) absorbers are necessary components for recent high-power accelerators in order to prevent beam instabilities (e.g. HOM- Beam Break Up instabilities) or the overheating of vacuum components. Several kinds of absorber materials, such as SiC, ferrite and Kanthal, have been investigated and applied in accelerators. Among these materials, ferrite has been found to be superior to others because of its higher HOM absorbing efficiency. However, because of its low tensile strength and small thermal expansion rate, it cannot be easily bonded to other metals thus limiting its use as a HOM absorber. We reported the success of the fabrication of ferrite-copper-blocks using the spark plasma sintering (SPS)-technique last year. This year we report testing with a high-power RF source and measuring gas desorption rate after baking and secondary electron yield.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA058  
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WEPVA059 Construction of the New Septum Magnet Systems for PF-Advanced Ring 3398
 
  • A. Ueda, S. Asaoka, T. Hondapresenter, S. Nagahashi, N. Nakamura, T. Nogami, H. Takaki, T. Uchiyama
    KEK, Ibaraki, Japan
 
  From July 2016 we are constructing a new beam transport (BT) line for the Photon Factory Advanced Ring (PF-AR). The new BT line was designed to transport the full energy 6.5-GeV beam directly from the LINAC, and the top up injection will be possible for the PF-AR. We designed and produced new pulsed septum magnet systems for this project. Two pulsed septum magnets are used for the injection of the 6.5-GeV beam. The septum magnets were constructed with a passive type magnet, a copper eddy current shield and a silicon steel magnetic shield. The magnetic fields of these magnets have been measured by the search coil method. We paid attention to evaluating eddy current losses of the SUS beam duct in the magnetic field measurement.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA059  
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WEPVA060 Construction of the New Kicker Magnet Systems for PF-Advanced Ring 3401
 
  • A. Ueda, S. Asaoka, T. Hondapresenter, S. Nagahashi, N. Nakamura, T. Nogami, H. Takaki, T. Uchiyama
    KEK, Ibaraki, Japan
 
  From July 2016 we are constructing a new beam transport (BT) line for the Photon Factory Advanced Ring (PF-AR). The new BT line was designed to transport the full energy 6.5-GeV beam directly from the LINAC, and the top up injection will be possible for the PF-AR. We designed and produced new kicker systems for this project. Three kicker magnets are used for the injection of the 6.5-GeV beam. The kicker magnets were designed as a window frame type ferrite core magnet. The magnetic fields of these magnets have been measured by the search coil method. We paid attention to evaluating eddy current losses of the metal coated ceramic duct in the magnetic field measurement.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA060  
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WEPVA061 High-Precision Pattern Power Supply of Kicker Magnet for Multi-Beamline Operation at SACLA 3404
 
  • C. Kondo, T. Fukui, T. Hara, T. Inagaki, Y. Otake, H. Tanaka
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
  • K. Fukami
    JASRI/SPring-8, Hyogo-ken, Japan
  • H. Kawaguchi, Y. Kawaguchi
    Nichicon (Kusatsu) Corporation, Shiga, Japan
  • S. Nakazawa
    SES, Hyogo-pref., Japan
 
  At the Japanese XFEL facility SACLA, two XFEL beamlines (BL2 and BL3) and an injection line to the SPring-8 storage ring are switched by a kicker magnet. This multi-beamline operation has been tested since February 2015, however, CSR effects at a dogleg beam transport to BL2 with a deflecting angle of 3 degree currently limit the peak current of the electron beam. In order to suppress and cancel out the CSR effects, new beam optics is introduced for the dogleg in January 2017. In the new optics, a deflecting angle of the first kicker magnet is increased to 1.5 degree, which is three times larger than that of the old optics. To drive the kicker magnet, a high-power pattern power supply has been developed. To achieve the maximum output of 300 A and 1 kV, SiC MOSFETs are used as switching modules. The newly developed power supply can generate bipolar trapezoidal current waveforms at 60 Hz, and the amplitude and polarity of each waveform are controlled from pulse to pulse according to the beam energy and destination. The target stability is 10 ppm (peak to peak). In this presentation, we report the design and operation results of the newly developed pattern power supply.  
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WEPVA062 Improvements of Vacuum System in J-PARC 3 GeV Synchrotron 3408
 
  • J. Kamiya, Y. Hikichi, M. Kinsho, Y. Namekawa, K. Takeishi, T. Yanagibashi
    JAEA/J-PARC, Tokai-mura, Japan
  • A. Sato
    Nippon Advanced Technology Co., Ltd., Tokai, Japan
 
  The RCS vacuum system has been upgraded since the completion of its construction towards the objectives of both better vacuum quality and higher reliability of the components. For the better vacuum quality, (1) pressure of the injection beam line was improved to prevent the H beam from converting to H0; (2) leakage in the beam injection area due to the thermal expansion was eliminated by applying the adequate torque amount for the clamps; (3) new in-situ degassing method of the kicker magnet was developed. For the reliability increase of the components, (1) A considerable number of fluoroelastmer seal was exchanged to metal seal with the low spring constant bellows and the light clamps; (2) TMP controller for the long cable was developed to prevent the controller failure by the severe electrical noise; (3) A number of TMP were installed instead of ion pumps in the RF cavity section as an insurance for the case of pump trouble.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA062  
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WEPVA063 Development of a New Pulsed Power Supply with the SiC-MOSFET 3412
 
  • T. Takayanagi, K. Horino, J. Kamiyapresenter, M. Kinsho, T. Ueno, K. Yamamoto
    JAEA/J-PARC, Tokai-mura, Japan
  • Y. Mushibe, A. Tokuchi
    Pulsed Power Japan Laboratory Ltd., Kusatsu-shi Shiga, Japan
 
  A new power supply has been developed using linear transformer driver (LTD) technology that adopts SiC-MOSFETs and capacitors without a thyratron switch or a pulse forming network (PFN) device. A new power supply was also designed by connecting the SiC-MOSFETs and the LTD modules in parallel-series. The output voltage and current were 40 kV and 4 kA, respectively with a pulse width of 1500 nsec at a repetition rate of 25 Hz. Furthermore, by adjusting the correction module, to an output voltage per stage of 1/1000, a resolution of the voltage correction of ±0.1 % could be achieved. It was possible to output the current with arbitrary timing by using a trigger input for each LTD module. As a result, fine adjustment of the output voltage waveform was possible within the order of nanoseconds. This new power supply with high voltage output, cur-rent output, and very fast pulse operation is one of the most important key technologies for a kicker system using SiC-MOSFETs. The design and preliminary test results of this prototype power supply are presented here.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA063  
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WEPVA064 The Pulsed Power Supplies of the SESAME Booster and Storage Ring 3415
 
  • E. Huttel, I.A. Abid, S.Kh. Jafar
    SESAME, Allan, Jordan
 
  SESAME the Synchrotron Radiation Light Source in Allan (Jordan) consists of an 800 MeV injector (original from BESSY I, Berlin, Germany) and a 2.5 GeV Storagering. Injection into the Booster is done by an electrostatic Septum and one stripline kicker. Extraction out of the Booster is done by means of a bumper magnet, a strip-line-line kicker and a direct driven in-vacuum septum. Injection into the Storagering is done by a direct driven out-off vacuum septum and one kicker. The pulses of all septa are full sine, the ones of the kicker half sine with exception of the extraction kicker (flat-top). Extraction Kicker and Storage ring injection kicker are switched by Thyratron, all others via transistors. This report describes the injection and extraction optics and the results of the commissioning.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA064  
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WEPVA065 High Precision Magnet Powering for the SESAME Storage Ring 3418
 
  • S.Kh. Jafar, I.A. Abid, A. Ismail
    SESAME, Allan, Jordan
  • E.O. Ari
    ASELSAN A.S., Ankara, Turkey
  • M.C. Bastos, T. Henschel
    CERN, Geneva, Switzerland
  • E.H. Yousefi
    ILSF, Tehran, Iran
 
  SESAME is the first synchrotron light source for the Middle East and is expected to start its operation mid-2017. It is composed of a 22 MeV Microtron, a 0.8 GeV booster synchrotron and a 2.5 GeV storage ring. The storage ring magnets and power supplies were designed, produced and validated under the framework of a collaboration between SESAME and CERN, supported by the European Commission. The power supply control strategy for the SESAME main ring follows the same model used in the LHC, where the power supplies are voltage sources bought from industry, to which a specially designed control unit and current sensors are added to implement a high precision current source. This strategy provides modularity, ease of maintenance, better control over performance and flexibility for the machine. Machine flexibility is further enhanced by individually powering the quadrupole magnets. In this paper, the powering strategy, design and validation of the magnet power supplies are described. Some of the challenges faced during those phases are discussed. Finally, performance results are presented, showing stability of the dipole power supply at nominal current of about 10 parts per million.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA065  
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WEPVA066 The ESS Target Proton Beam Imaging System as in-Kind Contribution 3422
 
  • E. Adli, R. Anderssonpresenter, D.M. Bang, O. Dorholt, H. Gjersdal, O.M. Røhne
    University of Oslo, Oslo, Norway
  • M.G. Ibison, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • S. Joshi
    University College West, Trollhätan, Sweden
  • T.J. Shea, C.A. Thomas
    ESS, Lund, Sweden
 
  Funding: This work is part of the Norwegian in-kind contribution to ESS.
The ESS Target Proton Beam Imaging System will image the 5 MW ESS proton beam as it enters the spallation target. The system will operate in a harsh radiation environment, leading to a number of challenges: development of radiation hard photon sources, long aperture-restricted optical paths, and fast electronics to provide rapid response to beam anomalies. The newly formed accelerator group at the University of Oslo is the in-kind partner for the Imaging System. This paper outlines the main challenges of the Imaging System and how they are addressed within the collaborative nature of the in-kind project.
 
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WEPVA067 Preliminary Results on the Resonant Excitation of THz Wakefield in a Multi-Mode Dielectric Loaded Waveguide by Bunch Train 3426
 
  • D. Wang, Y.-C. Du, W. Gai, W.-H. Huang, L. Niu, X.L. Su, C.-X. Tang, Q.L. Tian, L.X. Yan
    TUB, Beijing, People's Republic of China
  • S.P. Antipov
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • Y.F. Liang
    Tsinghua University, Beijing, People's Republic of China
 
  Funding: Work supported by the National Nature Science Foundation of China (NSFC Grants No.11475097) and the National Key Scientific Instrument and Equipment Development Project of China (Grants No. 2013YQ12034504)
We report the preliminary experimental results on the resonant excitation of THz wakefield in a multi-mode dielectric loaded waveguide (DLW) by electron bunch train at the Tsinghua University accelerator beamline. The bunch train with certain longitudinal periodicity was generated based on nonlinear longitudinal space charge oscillation [1]. By passing such bunch train through a multi-mode DLW, we observed selective excitation of the fifth longitudinal mode (TM05 mode) was resonantly excited. Future experiment plan is to tune the bunch train interval with a chicane in the beamline in order to selectively excite arbitrary mode for tunable THz radiation source with multi-mode DLWs.
*wangdan16@mail.tsinghua.edu.cn
*yanlx@mail.tsinghua.edu.cn
 
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WEPVA068 Design and Development of Accelerator Magnet Power Supply Based on SiC-MOSFET 3429
SUSPSIK111   use link to see paper's listing under its alternate paper code  
 
  • L. Yang, F. Long, Z.H. ZhenHua
    IHEP, Beijing, People's Republic of China
 
  SiC is a new type of semiconducting material with rapid development after the first generation and the second generation of semiconductor materials represented by silicon and gallium arsenide. SiC-MOSFET has a high frequency, high breakdown voltage, high temperature, radiation and many other points, suitable for future use in the accelerator magnet power supply. In this paper, the development and operation of a SiC-MOSFET-based accelerator magnet power supply are described in detail. The experiment results show that the performance of this power supply is superior to that of the same specification using Si-MOSFET. The power supply adopts one-way AC power supply, and the output stage adopts the full bridge circuit topology. The power device adopts C2M0040120D SiC-MOSFET, the working frequency is 30 kHz, the output current is ± 20A, the output voltage is ± 20V, and power is 400W. The Digital Power Supply Control Module (DPSCM) is used to realize high-precision digital closed-loop control, which supports on-line debugging and PC control. Power supply can be used to correct the magnet power, with high efficiency, high stability, and fast response and so on.  
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WEPVA070 Alignment and Calibration for Collimation System in CSNS/RCS 3432
 
  • J.B. Yu, L. Dong, L. Kang, B. Li, X.J. Nie, A.X. Wang, G.Y. Wang, X.L. Wang, J.S. Zhang
    IHEP, Beijing, People's Republic of China
  • J.X. Chen, T. Luo, C.J. Ning
    CSNS, Guangdong Province, People's Republic of China
 
  Funding: National Natural Science Foundation of China (Grant Nos.11375217)
In order to reduce the uncontrolled losses in the localized station, the beam collimation system has been performed for the 1.6GeV synchrotron of CSNS. The CSNS/RCS transverse collimation system is designed to be a two-stage system which consists of one primary collimator and four secondary collimators. All collimators had completed processing and now been installed in the tunnel. To meet the requirements of physical system, alignment for collimation system have to be done before circulating beams. This paper will show the alignment technique of collimation system. Then some problems during the alignment process will be mentioned. For the primary collimator will be replaced in second-stage of CSNS, and the alignment for the replaced collimator will be introduced finally.
 
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WEPVA071 Preliminary Conceptual Study of Next Generation Tau-Charm Factory at China 3436
 
  • Q. Luo
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  Funding: Work supported by National Natural Science Foundation of China 11375178 and the Fundamental Research Funds for the Central Universities, Grant No WK2310000046
As BEPC II would accomplish its mission in the next decade, research on high energy science demands a successor. The luminosity of this successor should be one or two orders higher than BEPC II, while the electron beam should be longitudinal polarized at the IP. This paper discusses the feasibility and key technologies of the next tau-charm collider: a greenfield new facility or an upgrade of BEPC II.
 
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WEPVA075 Labview-Based Software for Electron Gun Controller 3439
 
  • Z.X. Shao, H. Gao, W. Liupresenter, C.Y. Pan
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  Funding: Supported by the National Science Foundation of China (No: 21327901)
Instrument control can improve measurement level of automation. In the actual control of the accelerator electron gun, we need to obtain a voltage with different amplitudes for the filament. Boost and voltage regulator modules should be used in the 220V AC input conditions. In order to adjust the filament voltage and stabilize the filament current more convenient, we developed a control software based on LabVIEW.
 
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WEPVA077 Design of the Control System of Pulsed Power Supplies for WHMM Injection Bump Magnets 3442
 
  • J. Zhao, D.Q. Gao, H. Zhang, Z.Z. Zhou
    IMP/CAS, Lanzhou, People's Republic of China
 
  The injection bump system of the synchrotron of the Wuwei Heavy-ion Medical Machine(WHMM) consists of four horizontal bump magnets to merge the injection beam with the circulating beam. In order to control the injection beam with sufficient accuracy, the bump mag-nets need four pulsed power supplies with high speed, precision, reliability. The power supplies, whose IBGT (Insulated Gate Bipolar Transistor) are working in the linear area, are required to output the maximum current of 2900A. Furthermore, the current pulse is activated by synchronous triggering events, the current pulse frequen-cy is required about 30Hz, and that the pulse current falling edge should be less than 60us. In this paper, a control system for the pulsed power supplies was described in details. The commissioning results showed that the control system owned high reliability and flexible and that beam could be injected effectively into the synchrotron of the WHMM. In addition, one on-line current pulse waveform is shown in the result section.  
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WEPVA081 Topology Optimization for a Superconducting Cyclotron Main Magnet 3446
SUSPSIK109   use link to see paper's listing under its alternate paper code  
 
  • L.G. Zhang, K. Fan, S. Hu, L.X.F. Li, Z.Y. Mei, B. Qin, Z.J. Zeng
    HUST, Wuhan, People's Republic of China
  • W. Chen
    Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People's Republic of China
 
  Main magnet is the heaviest component in a superconducting cyclotron, which occupies a large amount of cost. Topology optimization method is implanted to minimize the weight of main magnet while keep the field performance, which will make significant economic benefit. Due to the powerful superconducting coils, the main magnet is driven into saturation, and the nonlinear effect of the material must be considered. If the ordinary standard density method is used for the main magnet structure optimization, the nonlinear B-H relation have to be interpolated and the sensitivity analysis is very complicated. In this paper, a proper 2D model is established and the optimization formulation is given using standard density method. Then, the optimized topology of the main magnet for a 250MeV superconducting proton cyclotron is designed.  
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WEPVA082 Technical Overview of the SOLARIS Low-Conductivity Water Cooling System 3449
 
  • P. Czernecki, P. Bulira, P. Gębala, J. Janiga, P. Klimecki
    Solaris National Synchrotron Radiation Centre, Jagiellonian University, Kraków, Poland
 
  National Synchrotron Radiation Centre Solaris started operation in May 2015. In order to receive heat deposited in various synchrotron devices during operation, a low-conductivity water (LCW) cooling system was installed. To fulfill all tasks of cooling system at an acceptable cost of investment and maintenance certain technical and economic conditions, i.e.:installation materials, LCW quality, hydraulic balancing system, automation, control and diagnostics, including the planned service intervals, have to be met. Within this presentation the design, construction and operation of the LCW cooling system will be discussed.  
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WEPVA084 Performance of the PAL-XFEL High Precision Magnet Power Supplies 3452
 
  • S.-H. Jeong, J.H. Han, Y.G. Jung, H.-S. Kang, D.E. Kim, H.-G. Lee, S.B. Lee, B.G. Oh, K.-H. Park, H.S. Suh
    PAL, Pohang, Kyungbuk, Republic of Korea
 
  In the PAL-XFEL, 632 magnet power supplies (MPS) have been operated since 2016. High current unipolar MPSs(>100A) were configured buck mode with single power stack or two. The corrector MPSs for low current were the H-bridge type for bipolar current driving. The nine different types of MPS were installed for beam dy-namics in the PAL-XFEL machine. All MPSs had been tested and confirmed their performances before installa-tion. We described here the status of the MPS operation after installation on 2016.  
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WEPVA085 Development of High Stabile Magnet Power Supply 3455
 
  • K.-H. Park, J.H. Han, S.-H. Jeong, Y.G. Jung, D.E. Kim, H.-G. Lee, S.B. Lee, B.G. Oh, H.S. Suh
    PAL, Pohang, Kyungbuk, Republic of Korea
 
  A high stable magnet power supply (MPS) was devel-oped, which was a bipolar type with 200A of the output current at the 40V of output voltage. The MPS has been implemented by the digital signal processing technology using the DSP, FPGA, ADCs and so on. The output cur-rent stability of the MPS showed about 4 ppm peak-to-peak in a short term experiment at the 200A of its full output current. This paper shows the several design con-siderations being implemented to this high stable MPS. Some experimental data such as output stability, some waveforms and so on are given in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA085  
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WEPVA087 Magnetic Measurements of NICA Booster Dipoles 3458
 
  • V.V. Borisov, A.V. Bychkov, A.M. Donyagin, O. Golubitsky, H.G. Khodzhibagiyan, S.A. Kostromin, M.M. Omelyanenko, M.M. Shandov
    JINR, Dubna, Moscow Region, Russia
  • A.V. Shemchuk
    JINR/VBLHEP, Dubna, Moscow region, Russia
 
  NICA is a new accelerator collider complex under construction at the Joint Institute for Nuclear Research in Dubna. NICA booster magnetic system consists of 40 dipole and 48 quadrupole superconducting magnets. Measurement of magnetic field parameters is assumed for each booster magnets. At the moment 20 series dipole magnets are assembled and have passed all tests. Booster dipole magnets are 2.14 m-long, 128 /65 mm (h/v) aperture magnets with design similar to Nuclotron dipole magnet but with curved (14.1 m radius) yoke. They will produce fields up to 1.8 T. The magnetic field parameters will be measured at warm (300 K) and cold (4.5 K) conditions. This paper describes magnetic measurements methods and developing of magnetic measurements system. The obtained results of magnetic measurements of 20 magnets are summarized here.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA087  
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WEPVA088 Testing of SC-Magnets of NICA booster synchrotron 3461
 
  • S.A. Kostromin, V.V. Borisov, A.M. Donyagin, A.R. Galimov, O. Golubitsky, H.G. Khodzhibagiyan, B.Yu. Kondratiev, S.A. Korovkin, A.V. Kudashkin, G.L. Kuznetsov, D. Nikiforov, A.V. Shemchuk, A.Y. Starikov, A. Tikhomirov
    JINR, Dubna, Moscow Region, Russia
  • T.E. Serochkina
    JINR/VBLHEP, Dubna, Moscow region, Russia
 
  Serial tests of sc-magnets of NICA Booster started at the dedicated facility of LHEP JINR. Magnets' assembly and testing workflow are presented. Main steps of the magnet preparation to the cryogenics tests are described. First results of serial tests are presented and discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA088  
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WEPVA089 Magnetic Measurement System for the NICA Quadrupole Magnets 3464
 
  • A.V. Shemchuk
    JINR/VBLHEP, Dubna, Moscow region, Russia
  • V.V. Borisov, A.V. Bychkov, A.M. Donyagin, O. Golubitsky, H.G. Khodzhibagiyan, S.A. Kostromin, M.M. Omelyanenko, M.M. Shandov
    JINR, Dubna, Moscow Region, Russia
 
  NICA is a new accelerator collider Nuclear Research (JINR) in Dubna. More than 250 superconducting magnets need for the NICA booster and collider. These magnets will be assembled and tested at the new test facility in the Laboratory of High Energy Physics JINR. A method of measuring the quality of the magnetic field in the aperture of the quadrupole magnet for the booster synchrotron is described. Commissioning of equipment for magnetic measurements in the aperture of the doublet of quadrupole lenses is described.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA089  
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WEPVA090 The Vacuum System of MAX IV Storage Rings: Installation and Conditioning 3468
 
  • E. Al-Dmour, M.J. Grabski
    MAX IV Laboratory, Lund University, Lund, Sweden
 
  The installation of the vacuum system of the 3 GeV storage ring was started in November 2014 and finished in May 2015. In August 2015 the commissioning of the storage ring started, the first stored beam has been achieved on the 15th of September 2015. The installation of the vacuum system of the 1.5 GeV storage ring was done from September 2015 and the main part finished in December 2015, the connection to the Linac with the transfer line has been done in August 2016. In September 2016 the commissioning of the 1.5 GeV storage ring started with the first stored beam achieved on the 30th of September 2016. The vacuum system conditioning for the two rings was successful; the average dynamic pressure reduction and the increase in the lifetime with the accumulated beam dose is a demonstration of the good performance of the vacuum system. The installation procedure and the results of the conditioning together with the latest developments are introduced here.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA090  
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WEPVA094 Study of an Improved Beam Screen Design for the LHC Injection Kicker Magnet for HL-LHC 3471
 
  • V. Vlachodimitropoulos, M.J. Barnespresenter, L. Ducimetière, L. Vega Cid, W.J.M. Weterings
    CERN, Geneva, Switzerland
 
  During Run 1 of the LHC, one of the injection kicker magnets (MKIs) occasionally exhibited an excessively high ferrite temperature, caused by coupling of the high intensity beam to the real impedance of the magnet. Beam-screen upgrades have been very effective in reducing beam coupling impedance during Run 2. However, temperature measurements during LHC operation have shown that one end of the MKIs ferrite yoke is consistently hotter than the other: this effect is due to highly non-uniform beam induced power deposition along the kicker. Electromagnetic and thermal simulations show that part of the ferrite yoke will be above its Curie temperature when the LHC is operated with HL-LHC beam parameters, which could increase the turn-around time between fills of the LHC. An impedance mitigation study is presented in this paper with emphasis on the effect of the beam screen layout upon both total beam induced power deposition and its longitudinal distribution. Results of complex thermal simulations, to benchmark the effectiveness of the proposed schemes, are reported. To validate the proposed modification a test bench measurement was performed and preliminary results are discussed  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA094  
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WEPVA095 Preliminary Estimate of Beam Induced Power Deposition in a FCC-hh Injection Kicker Magnet 3475
 
  • A. Chmielinska, M.J. Barnespresenter, W. Bartmann, F. Burkart, B. Goddard
    CERN, Geneva, Switzerland
  • A. Chmielinska
    EPFL, Lausanne, Switzerland
 
  The Future Circular Collider for hadrons (FCC-hh) will require a fast injection kicker system that is highly reliable and that does not limit accelerator performance. Important considerations in the design of such a system are machine protection constraints, collider filling factor and hence rise and fall times of the kicker magnet field. Fast rise time kicker magnets are generally ferrite loaded transmission line type magnets with a rectangular shaped aperture. The beam coupling impedance of the kicker magnets is crucial, as this can be a dominant contribution to beam instabilities. In addition, beam-induced heating of the ferrite yoke due to the real component of the longitudinal beam coupling impedance needs to be controlled: if the ferrite temperature exceeds the Curie point this impacts the ability to inject beam and hence the availability of the machine. This paper presents estimates for the beam induced power deposition in the ferrite yoke, based on a calculated FCC beam spectrum and an analytical model of longitudinal impedance for unshielded kicker magnets.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA095  
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WEPVA096 Thermal Analysis of the LHC Injection Kicker Magnets 3479
 
  • L. Vega Cid, M.J. Barnespresenter, V. Vlachodimitropoulos, W.J.M. Weterings
    CERN, Geneva, Switzerland
  • A. Abánades
    ETSII UPM, Madrid, Spain
 
  Funding: Research supported by the HL-LHC project.
The CERN Large Hadron Collider LHC is equipped with two fast pulsed magnet systems (MKIs) that inject particle beams coming from the injector chain. Operation with high intensity beams for many hours can lead to significant beam induced heating of the ferrite yokes of the MKIs. When the ferrite exceeds the Curie temperature of 125°C it loses its magnetic properties, preventing further injection until the ferrite cools down, potentially causing a delay of several hours. Hence important upgrades of the beam-screen were implemented after Run 1 of LHC. However, the High-Luminosity (HL) LHC will be operated with significantly higher intensity beams and hence additional measures are required to limit the ferrite temperature. These magnets operate under ultra-high vacuum conditions: convection is negligible and, as a result of low emissivity of the inside of the vacuum tanks, thermal radiation is limited. A detailed study of the thermal behaviour of these magnets is reported and compared with measurements. In addition several options to improve cooling of the ferrites are presented and analysed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA096  
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WEPVA097 Upgrading the SPS Fast Extraction Kicker Systems for HL-LHC 3483
 
  • M.J. Barnes, M.S. Beck, H.A. Day, L. Ducimetière, E. Garcia-Tabares Valdivieso, B. Goddard, H. Neupert, A. Romano, L. Vega Cid, W.J.M. Weterings
    CERN, Geneva, Switzerland
  • C. Zannini
    ADAM SA, Geneva, Switzerland
 
  The CERN SPS has two fast extraction systems, each consisting of travelling wave kicker magnets (MKEs). The beam induced heating in the ferrite yoke of these magnets was historically kept to an acceptable level by implementing water cooling of the kicker magnets: in addition serigraphy was applied on the surfaces of the ferrite yoke facing the beam. Nevertheless, high intensity beams needed in the future for HL-LHC will significantly increase the beam induced heating, potentially raising the MKE ferrite yoke temperature to its Curie point. Hence detailed studies of longitudinal beam coupling impedance were carried out to identify simple but effective methods of further reducing beam induced power deposition. Based on the results of these studies, and in the framework of the LHC Injectors Upgrade (LIU) project, an upgraded MKE kicker magnet was installed during the 2015-2016 shutdown. This paper reports and compares results of predictions, laboratory measurements, temperature measurements during SPS operation, and machine development studies. Measurements of both dynamic pressure rise in the upgraded magnet and Secondary Electron Yield, on samples, are also reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA097  
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WEPVA098 Measurements on a 12.5 kV Prototype Inductive Adder for the CLIC DR Extraction Kickers 3487
 
  • J. Holma, M.J. Barnespresenter
    CERN, Geneva, Switzerland
 
  The CLIC study is investigating the technical feasibility of an electron-positron collider with high luminosity and a nominal centre-of-mass energy of 3 TeV. The pre-damping rings and damping rings (DRs) will produce ultra-low emittance beam with high bunch charge. To avoid beam emittance increase, the DR kicker systems must provide extremely stable field pulses during injection and extraction of bunches. The DR extraction kicker system consists of a stripline kicker and two pulse modulators. The current specifications for the modulators call for pulses with 160 ns or 900 ns flattop duration of ±12.5 kV and 305 A, with ripple of not more than ±0.02 % (±2.5 V). An inductive adder is a very promising approach to meeting the specifications because analogue modulation methods can be applied to adjust the output waveform. Recently, the first full-scale, 20-layer, 12.5 kV prototype inductive adder has been assembled at CERN and testing has commenced. The goal is to tailor the output waveform of the prototype to the waveform required for the DR extraction stripline kicker. The results of the initial tests and measurements are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA098  
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WEPVA099 Influence of Conducting Serigraphy Upon Field Pulse Shape of the SPS Extraction Kicker Systems 3491
 
  • A. Adraktas, M.J. Barnespresenter, L. Ducimetière
    CERN, Geneva, Switzerland
 
  Fast pulsed magnets with ferrite yokes are used for beam extraction from the CERN SPS accelerator. These kickers are transmission line type magnets with a rectangular shaped aperture through which the beam circulates. Unless special precautions are taken, the beam impedance of the yoke can provoke significant induced heating, especially for high intensity beams. Previous upgrades of the SPS extraction kicker magnets have included silver fingers serigraphed on the surface of the ferrite facing the beam, to help shield the ferrite yoke from circulating beam. Beam based measurements of the extracted beam indicated that the serigraphy may influence the shape of the field pulse, causing it to increase slightly in magnitude during the flat-top. Hence theoretical studies have been carried out to determine whether the serigraphy influences the field pulse: these studies are reported in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA099  
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WEPVA100 Operational Experience of the Upgraded LHC Injection Kicker Magnets During Run 2 and Future Plans 3495
 
  • M.J. Barnes, A. Adraktas, G. Bregliozzi, L. Ducimetière, B. Goddard, B. Salvant, J. Sestak, L. Vega Cid, W.J.M. Weterings, C. Yin Vallgren
    CERN, Geneva, Switzerland
 
  During Run 1 of the LHC, one of the injection kicker magnets caused occasional operational delays due to beam induced heating with high bunch intensity and short bunch lengths. In addition, there were also sporadic issues with vacuum activity and electrical flashover of the injection kickers. An extensive program of studies was launched and significant upgrades were carried out during Long Shutdown 1 (LS 1). These upgrades included a new design of beam screen to reduce both beam coupling impedance of the kicker magnet and the electric field associated with the screen conductors, hence decreasing the probability of electrical breakdown in this region. This paper presents operational experience of the injection kicker magnets during the first years of Run 2 of the LHC, including a discussion of faults and kicker magnet issues that limited LHC operation. In addition, in light of these issues, plans for further upgrades are briefly discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA100  
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WEPVA101 Review of Stripline Beam Impedance: Application to the Extraction Kicker for the CLIC Damping Rings 3499
 
  • C. Belver-Aguilar, M.J. Barnespresenter
    CERN, Geneva, Switzerland
 
  The beam coupling impedance of the stripline kicker for beam extraction from the CLIC Damping Rings (DRs) has been studied analytically, numerically with CST Particle Studio (PS) and measured in the laboratory, although not all the results were understood. In order to have a better knowledge about the beam coupling impedance of a stripline kicker, a simple model has been first studied, with flat electrodes and a cylindrical beam pipe. From this preliminary study, a new approach for the dipolar component of the horizontal impedance has been derived, when considering both odd and even operating modes of the striplines. This new approach has been used to understand the differences found between the predicted transverse impedance and the two wire measurements carried out in the laboratory for the prototype CLIC DR striplines. Future tests of beam coupling impedance with beam in the ALBA Synchrotron Ligth Source will complete this study.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA101  
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WEPVA102 Design of the New CERN nTOF Neutron Spallation Target: R&D and Prototyping Activities 3503
SUSPSIK112   use link to see paper's listing under its alternate paper code  
 
  • R. Esposito, M. Calviani, T. Coiffet, M. Delonca, L. Dufay-Chanat, E. Gallay, M. Guinchard, D. Horvath, T. Koettig, A.P. Perez, A.T. Perez Fontenla, A. Perillo-Marcone, S. Sgobba, M.A. Timmins, A. Vacca, V. Vlachoudis
    CERN, Geneva, Switzerland
  • M. Beregret
    UTBM, Belfort, France
  • L. Gomez Pereira
    University of Vigo, Pontevedra, Spain
  • F. Latini
    University of Rome La Sapienza, Rome, Italy
  • R. Logé
    EPFL, Lausanne, Switzerland
 
  A new spallation target for the CERN neutron time-of-flight facility will be installed during Long Shutdown 2 (2019-2020), with the objective of improving operational reliability, avoiding water contamination of spallation products, corrosion/erosion and creep phenomena, as well as optimizing it for the 20 m distant vertical experimental area 2, whilst keeping the same physics performances of the current target at the 200 m far experimental area 1. Several solutions have been studied with FLUKA Monte Carlo simulations in order to find the optimal solution with respect to neutron fluence, photon background, resolution function, energy deposition and radiation damage. Thermo-mechanical studies (including CFD simulations) have been performed in order to evaluate and optimize the target ability to withstand the beam loads in terms of maximum temperatures reached, cooling system efficiency, maximum stresses, creep and fatigue behaviour of the target materials, leading to a preliminary mechanical design of the target. This paper also covers the further prototyping and material characterization activities carried out in order to validate the feasibility of the investigated solutions.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA102  
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WEPVA103 Renovation of CERN Antiproton Production Target Area and Associated Design, Testing and R&D Activities 3506
 
  • C. Torregrosa, M.E.J. Butcher, M. Calviani, A. De Macedo, S. De Man, R. Ferriere, E. Grenier-Boley, B. Lefort, E. Lopez Sola, A. Perillo-Marcone, M.A. Timmins
    CERN, Geneva, Switzerland
 
  In the Antiproton Decelerator (AD) Target Area antiprotons are produced by the collisions of 26 GeV/c proton beam with a fixed target. They are then collected by a 400 kA pulsed magnetic horn, momentum selected and injected into the AD facility. The area has been in operation since the 80s, keeping most of the equipment dating back to this period. A major upgrade is foreseen during the CERN's Long Shutdown 2 to guarantee the next decades of antiproton physics. Among other R&D activities, three main systems are within the scope of this upgrade; (i) a new antiproton target design, pressurized-air-cooled and with a new core configuration based on the results from the HiRadMat27 experiment. (ii) Manufacturing of a set of new magnetic horns and testing them using a dedicated test bench replicating the real horn setup. (iii) Design of new target and horn's trolleys, which are responsible for their positioning as well as providing an efficient long term maintenance giving the high radioactivity of the area. This paper presents an overview of these and other critical activities associated to the renovation of the target area, including status and direction of the new proposed designs.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA103  
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WEPVA105 Upgrading of Ageing CERN Underground Infrastructure to Fulfil the Space Requirements of New Facilities at CERN 3510
 
  • A. Martínez Sellés, E. Carlier, V. Di Murro, B. Goddard, E. Gschwendtner, F.J. Magnin, R.F. Morton, J.A. Osborne
    CERN, Geneva, Switzerland
  • V. Di Murro
    University of Cambridge, Cambridge, United Kingdom
 
  Particle accelerator technology is constantly being developed, and new equipment and machines replace the former ones to keep pushing the energy and intensity frontiers. Therefore, in order to meet the space requirements of new equipment, the infrastructure often needs to be modified, and given its rigid nature, this presents a challenge for the civil engineers to provide the needed space without compromising the safety and serviceability of the structures. In this paper two underground works are presented: a new cross-passage tunnel for the AWAKE experiment completed in 2014 and the future SPS Beam Dump. The challenges that must be faced are: (a) to make sure that the movements of the adjacent structures remain within admissible limits, (b) to design and execute the works such that the life span of the structure is not reduced, (c) To ensure the effectiveness of existing and new drainage systems during and after the works. For these purposes, in the frame of future tunnel asset management, the use of novel and conventional monitoring techniques plays a crucial role as it can predict in real time potential tunnel deformations which can lead, in the worst scenario, to tunnel failure  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA105  
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WEPVA106 A Consolidation Roadmap for the CERN Power Converters 3514
 
  • D. Nisbet, J.-P. Burnet
    CERN, Geneva, Switzerland
 
  At CERN the Electrical Power Converter group is re-sponsible for the design and exploitation of more than 5000 power systems throughout the accelerator complex, powering predominantly magnet circuits, in addition to RF and electro-static systems. Currently, a variety of systems are in operation, in some cases these are over 30 years old. Furthermore, the group must maintain operationally a total of six hardware platforms, each with dedicated software. In light of this, a consolidation roadmap has been determined to rejuvenate the power converter complex and to reduce the total number of control platforms. This paper presents a summary of the CERN power converter equipment to be consolidated, and the roadmap to achieve consolidation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA106  
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WEPVA108 Operational Feedback and Analysis of Current and Future Designs of the Injection Protection Absorbers in the Large Hadron Collider at CERN 3517
 
  • D. Carbajo Perez, N. Biancacci, C. Bracco, G. Bregliozzi, M. Calviani, M.I. Frankl, L. Gentini, S.S. Gilardoni, G. Iadarola, I. Lamas Garcia, A. Lechner, A. Perillo-Marconepresenter, B. Salvant
    CERN, Geneva, Switzerland
 
  Two injection protection absorbers, so-called TDIs (Target Dump Injection), are installed close to Interaction Points IP2 and IP8 of the Large Hadron Collider (LHC) right downstream of the injection kicker magnets (MKI). Malfunction or timing errors in the latter lead to wrong steering of the beam, which must then be intercepted by the TDI to avoid downstream equipment (which includes superconducting magnets) damage. In recent years, MKI failures during operation have brought to light opportunities for improvement of the TDI. The upgrade of this absorber, so-called TDIS (where S stands for segmented), is conceived as part of the High Luminosity-LHC (HL-LHC) project and those operational issues are taken into account for its design. The present document describes not only the aspects related to the current TDI performance and their impact in its successor's design but also the key modifications to cope with the stronger requirements associated to the higher luminosity goal.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA108  
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WEPVA109 Design of the New PS Internal Dumps, in the Framework of the LHC Injector Upgrade (LIU) Project 3521
 
  • G. Romagnoli, J.A. Briz Monago, M. Calviani, J.J. Esala, E. Grenier-Boley, A. Masi, F.-X. Nuiry, A. Perillo-Marconepresenter, T. Polzin, V. Vlachoudis
    CERN, Geneva, Switzerland
 
  For the LHC injectors upgrade (LIU) at CERN, the two PS (Proton Synchrotron) dumps will be redesigned and upgraded for the new high intensity beams. The EN-STI group is in charge of the design and installation of the new dumps, foreseen for the next CERN's Long Shutdown in 2019-2020. As internal dumps, the PS dumps have been installed in 1975 directly in the PS vacuum ring between the main bending magnets and they are operating since then. The dumps enter the beam line when requested by beam operation, with a 6 kg Cu block moved quickly with a spring-based mechanism. This Cu block is not expected to survive the impact of the future beams. A new design is presented for the dump core based on FLUKA-ANSYS coupled simulations. The dumps should work with any PS beam foreseen within LIU, be water cooled in ultra-high vacuum medium, and enter the beam chamber in less than 250 ms. The dump should be used 200000 times per year, with a lifetime of 20 years, with almost zero maintenance. The new challenging design is based on an oscillating thin blade shaving turn after turn the circulating beam. The material considered for the blade are Cu, Ti or CuCrZr with embedded cooling channels.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA109  
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WEPVA110 Analysis and Operational Feedback on the New Design of the High Energy Beam Dump in the CERN SPS 3524
 
  • P. Rios Rodriguez, J.A. Briz Monago, M. Calviani, K. Cornelis, S. De Man, R. Esposito, S.S. Gilardoni, B. Goddard, J.L. Grenard, D. Grenier, M. Grieco, J. Humbert, V. Kain, F.M. Leaux, C. Pasquino, A. Perillo-Marconepresenter, J.R.F. Poujol, S. Sgobba, D. Steyart, F.M. Velotti, V. Vlachoudis
    CERN, Geneva, Switzerland
 
  CERN's Super Proton Synchrotron (SPS) high-energy internal dump (Target Internal Dump Vertical Graphite, known as TIDVG) is required to intercept beams from 102 to 450 GeV. The equipment installed in 2014 (TIDVG#3) featured an absorbing core composed of different materials surrounded by a water-cooled copper jacket, which hold the UHV of the machine. An inspection of a previous equipment (TIDVG#2) in 2013 revealed significant beam induced damage to the aluminium section of the dump, which required imposing operational limitations to minimise the risk of reproducing this phenomenon. Additionally, in 2016 a vacuum leak was detected in the dump assembly, which imposed further limitations, i.e. a reduction of the beam intensity that could be dumped per SPS supercycle. This paper presents a new design (TIDVG#4), which focuses on improving the operational robustness of the device. Moreover, thanks to the added instrumentation, a careful analysis of its performance (both experimentally and during operation) will be possible. These studies will help validating technical solutions for the design of the future SPS dump to be installed during CERN's Long Shutdown 2 in 2020 (TIDVG#5).  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA110  
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WEPVA111 Change of Critical Current Density in Nb-Ti and Nb3Sn Strands After Millisecond Heating 3528
SUSPSIK110   use link to see paper's listing under its alternate paper code  
 
  • V. Raginel, K. Kulesz, M. Mentink, R. Schmidt, A.P. Verweij, D. Wollmann
    CERN, Geneva, Switzerland
  • D. Kleiven
    NTNU, Trondheim, Norway
 
  The damage mechanisms and limits of superconducting magnet components due to direct beam impact are not well understood. The energy deposition from beam losses can cause significant temperature rise and mechanical stress in the magnet coils, which can lead to a degradation of the insulation strength and critical current of the superconductor. An improved understanding of these mechanisms is not only important for the LHC in view of the planned increase in beam brightness, but also for other high energy accelerators using superconducting magnets. An experimental road map has been defined to study these damage mechanisms. Experiments have been performed with Nb-Ti and Nb3Sn strands and cable stacks at room temperature. This contribution focuses on the experimental study on the effect of millisecond heating on superconducting strands.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA111  
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WEPVA112 Characterisation of the Mechanical Behaviour of Superconducting Cables Used in High Field Magnets From Room Temperature Down to 77K 3532
 
  • O. Sacristan De Frutos, M. Daly, P. Ferracin, C. Fichera, M. Guinchard, T. Mikkola, F. Savary, G. Vallone
    CERN, Geneva, Switzerland
 
  A comprehensive knowledge of the mechanical properties of the superconducting cable used in high-field magnets is of paramount importance to study and model the behaviour of the magnet coil from assembly to the operational conditions at cryogenic temperature. The mechanical characterisation of such kind of materials presents practical challenges associated with the heterogeneity of the materials, the geometry, size and quality of the samples that can be produced out of actual cables. These constraints impose the undertaking of such measurements from a nonstandard approach, and hence the development of tailor-made tooling. An extensive characterisation campaign for the determination of the mechanical properties of the superconducting cable at room and cryogenic temperature was launched at CERN in order to determine the most relevant mechanical properties of the superconducting cables used in the MQXF and 11T magnets. This paper describes the design of the tooling developed for this specific application as well as the experimental set-up used for the tests, and discusses the outcomes of the matrix of tests performed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA112  
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WEPVA113 Thermo-Physical and Mechanical Characterisation of Novel Materials under Development for HL-LHC Beam Intercepting Devices 3536
 
  • O. Sacristan De Frutos, A. Bertarelli, L. Bianchi, F. Carra, J. Guardia, M. Guinchard, S. Redaelli
    CERN, Geneva, Switzerland
 
  Funding: The research leading to these results has received funding from the European Commission under the FP7 Research Infrastructures project EuCARD-2, grant agreement no.312453
The collimation system for high energy particle accelerators as HL-LHC, must be designed to withstand the close interaction with intense and energetic particle beams, safely operating over an extended range of temperatures in extreme conditions (pressure, strain-rate, radiation), which are to become more demanding with the High Luminosity LHC. In order to withstand such conditions, the candidate materials must possess among other properties outstanding thermal shock resistance and high thermal and electrical conductivity, condition only met by advanced or novel materials. Therefore, an extensive R&D program has been launched to develop novel materials capable of replacing or complementing materials used for present collimators. So far, Molybdenum Carbide - Graphite and Copper-Diamond composites have been identified as the most promising materials. Literature data are scarce or non-existing for these materials. For this reason the successive characterisation campaigns constitute a linchpin of the R&D program. This paper reviews the experimental program followed for the thermo-physical and mechanical characterisation of the materials, and discusses the most relevant results.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA113  
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WEPVA114 Optimising Machine-Experiment Interventions in HL-LHC 3540
 
  • F. Sanchez Galan, C. Adorisio, I. Bergstrom, D. Brethoux, S. Evrard, A. Gaddi, L.P. Krzkempek, M. Lazzaroni, J. Perez Espinos, M. Raymond, H. Vincke
    CERN, Geneva, Switzerland
 
  Funding: This Research is supported by the HL-LHC project
The luminosity reach of the HL-LHC experiments implies new constraints for the protection of the inner triplets from the machine debris. In general activation levels will increase a factor of 15-30 from the 2015 values (LS1), affecting both radiation tolerance of equipment and maintenance scenarios. The design of new equipment takes into account these constraints and the entire layout of tunnel equipment near the interaction regions will al-low for simplified maintenance. In particular, new ab-sorbers will replace the existing protection of the ma-chine-experiment cavern boundaries, with an optimised layout of the region. This paper summarises the main constraints (both physical and operational) existing at the region, together with the solutions adopted to reduce worker's dose.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA114  
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WEPVA116 HL-LHC Inner Triplet Powering and Control Strategy 3544
 
  • S. Yammine, H. Thiesen
    CERN, Geneva, Switzerland
 
  In order to achieve the target 3000 fb-1 integrated field for the HL-LHC (High Luminosity ' Large Hadron Collider) at ATLAS and CMS, new large aperture quadrupoles are required for the final focusing triplet magnets before the interaction points. These low-' magnets, based on the Nb3Sn technology, deliver a peak field of 11.4 T. They consist of two outer quadrupoles, Q1 and Q3 and a central one divided into two identical magnets, Q2a and Q2b. To optimize the powering and the beam dynamics of these triplets, the quadrupoles will be powered in series by a single high-current two quadrants (2-Q) converter [18 kA, ±10 V]. Three 4-Q trim power converters are added over Q1 [±2 kA, ±10 V], Q2a [±0.12 kA, ±10 V] and Q3 [±2 kA, ±10 V] to account for possible transfer function difference between the quadrupoles. This paper presents the powering scheme of the four mentioned coupled circuits. A digital control strategy, using four standard LHC digital controllers, to decouple the four systems and to achieve a high precision control is proposed and discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA116  
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WEPVA117 Preliminary Mechanical Design Study of the Hollow Electron Lens for HL-LHC 3547
 
  • C. Zanoni, G. Gobbi, D. Perini
    CERN, Geneva, Switzerland
  • G. Stancari
    Fermilab, Batavia, Illinois, USA
 
  A Hollow Electron Lens has been proposed in order to improve performance of halo control and collimation in the Large Hadron Collider in view of its High Luminosity upgrade (HL-LHC). The concept is based on a beam of electrons that travels around the protons for a few meters. The electron beam is produced by a cathode and then guided by a strong magnetic field generated by a set of solenoids. Mechanical design and integration require a preliminary knowledge of the optimal configuration of the solenoids that drive the electron trajectories. The estimation of such trajectories by means of a dedicated Matlab tool is presented. The influence of the main geometrical and electrical parameters is analysed and discussed. The main mechanical design choices are also outlined along with the concept of the electron collector. The aim of this paper is to provide an overview of the feasibility study of the Electron Lens for LHC. The methods used in this study also serve as examples for future mechanical and integration designs of similar devices.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA117  
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WEPVA120 Beam Dynamics Simulation for EPU200 in TPS 3551
 
  • M.-S. Chiu, C.H. Chen, J.Y. Chen, P.J. Chou, T.Y. Chungpresenter, Y.-C. Liu, F.H. Tseng
    NSRRC, Hsinchu, Taiwan
 
  The Taiwan Photon Source (TPS) is a low-emittance 3-GeV light source at Natioal Synchrotron Radiation Research Center (NSRRC). Five in-vacuum undulator beamlines were delivered to users on Sep. 22, 2016. To generate 10 ~ 500 eV photon with variuos polarizations, users proposed a new EPU : EPU200. In this paper, we present the preliminary results of beam dynamics simulation for EPU200.  
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WEPVA121 Thermal Experimet Results on TPS Beam Position Monitors 3554
 
  • Y.T. Huang, C.K. Chanpresenter, J. -Y. Chuang, I.C. Sheng, Y.C. Yang
    NSRRC, Hsinchu, Taiwan
 
  Beam position monitors mounted in straight sections exhibit an unusual temperature rise which is attributed to poor thermal and electrical conductivity of the stainless steel BPM chamber, to the vicinity to RF-bellows, and the large button electrode size to get superior signal levels. Thermocouples tied to BPM flanges and RF bellows show that the temperature could reach 50 oC when storing a beam current of 400 mA and BPMs located between two RF-bellows in RF cavity sections responds by even 5-10 oC higher values than average. To resolve this issue, off site experiments and simulations were conducted to further understand the heat flow in the whole structure. In this paper we discuss more details of these studies.  
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WEPVA122 Two Year Operational Experience With the Tps Vacuum System 3557
 
  • Y.C. Yang, C.K. Chanpresenter, J. -Y. Chuang, Y.T. Huang, C.C. Liang, I.C. Sheng
    NSRRC, Hsinchu, Taiwan
 
  The Taiwan Photon Source (TPS), a 3-GeV third generation synchrotron light source, was commissioned in 2014 December and is now currently operated in top-up mode at 300mA for users. During the past two years, the machine was completed to meet design goals with among others the installation of superconducting cavities (SRF), the installation of insertion devices (ID) and the correction of vacuum chamber structure downstream from the IDs. The design goal of 500mA beam current was achieved with a total accumulated beam dose of more than 1000Ah, resulting in three orders of magnitude reduction of out-gassing. As the beam current was increased, a few vacuum problems were encountered, including vacuum leaks, unexpected pressure bursts, etc. Vacuum related issues including high pressure events, lessons learned and operational experience will be presented and discussed in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA122  
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WEPVA123 Beam Cleaning of the Vacuum System of the TPS Storage Ring without Baking in Situ 3561
 
  • C.K. Chan, C.-C. Chang, B.Y. Chen, C.M. Cheng, Y.T. Cheng, J. -Y. Chuang, Y.M. Hsiao, Y.T. Huang, I.C. Sheng, C. Shueh, L.H. Wu, Y.C. Yang
    NSRRC, Hsinchu, Taiwan
 
  A maintenance procedure without baking in situ has been successfully developed and applied to maintain and upgrade the TPS storage ring vacuum system to shorten the machine downtime. The data of photon-stimulated desorption(PSD) reveal that no obvious discrepancy between the in-situ baked and the non-in-situ baked vacuum systems. A beam conditioning dose of extent only 11.8 A·h is required to recover rapidly the dynamic pressure of an unbaked vacuum system to its pre-intervention value according to the TPS maintenance experience.  
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WEPVA127 Design of a 3.5 T Superconducting Multipole Wiggler 3564
 
  • J.C. Jan, C.-H. Chang, H.-H. Chen, S.D. Chen, T.Y. Chungpresenter, C.-S. Hwang, F.-Y. Lin, G.-H. Luo
    NSRRC, Hsinchu, Taiwan
 
  A 3.5 T superconducting multipole wiggler (SMPW) has been designed through the collaboration of National Synchrotron Radiation Research Center (NSRRC) and Synchrotron Light Research Institute (SLRI). The SMPW will support the hard X-ray source for the X-ray absorption spectroscopy (XAS) beamline in SLRI. The design concept of the SMPW follows from, and improves on, the operating experience of the superconducting magnet in NSRRC. An improvement of the operation and compatible with the cooling capacity of the cryogenic system, is the design goal. A quick and easy recovery of the magnet from a quench event is also required. The design of the magnet circuit and the mechanical of the SMPW are also discussed herein.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA127  
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WEPVA128 The Data Acquisition System and Inspection Equipment on Vibration Evaluation for Deionized and Cooling Water Pumps in TPS 3568
 
  • Y.-H. Liu, Y.-C. Chung, C.K. Kuanpresenter, Z.-D. Tsai
    NSRRC, Hsinchu, Taiwan
 
  The purpose of this paper is to evaluate the vibration amplitude and spectrum for TPS water pump systems. The utility systems operate continuously since 2014, some of deionized and cooling water pumps produced higher vibration amplitude and noise during operation. The possibly reason could be poor system accuracy, inappropriate installation and commission adjustment. The data acquisition system on vibration evaluation for deionizes water pumps was established in 2016. Accord-ing to the long-tern vibration amplitude recording, the system operational status could be clarified. After vibra-tion test for several months, the bearing of booster deion-ized water pump was found abrasive since coupling be-tween motor and pump misaligned. Besides, the founda-tion of copper deionized water pump system was broken and observed by rapidly increase vibration amplitude in short term. The water pump systems were repaired and maintained base on vibration evaluation. There is still some remain problems for deionized and cooling water pump systems. The utility systems could prevent mal-function through regular vibration inspection and daily data acquisition.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA128  
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WEPVA129 Arc-Flash Hazard and Protection for Electric Switchboard at NSRRC 3571
 
  • T.-S. Ueng, Y.F. Chiu, C.K. Kuanpresenter, K.C. Kuo, Y.-C. Lin
    NSRRC, Hsinchu, Taiwan
 
  During the operation of electrical equipment the arc-flash accident could damage the equipment and endanger the working personnel. In order to prevent this type of accidents from happening and to minimize the damages, a delicate setup is being installed inside the electric switchboard for suppressing the accidents at the initial stage of arcing at NSRRC's power system. The installed device includes the arc sensor, the smoke detector, the high rupturing capacity fuse, the circuit breaker and the protection relay. Further improvement on preventing the arc-flash accidents is also under study.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA129  
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WEPVA130 Simulation the Iterative Learing Control Applied to the TPS Booster Ring Quadruple Magnet Power Supply 3574
 
  • B.S. Wang, Y.-C. Chien, C.Y. Liu, K.-B. Liu, Y.S. Wong
    NSRRC, Hsinchu, Taiwan
 
  In the newly built TPS (Taiwan Photon Source), the AC power supplies of the Booster ring are required to operate in DC and AC mode with accuracy. Especially in AC mode, during the booster ramping process, the current ramping profiles of the Quadruple Magnets have to track that of the Dipole AC power supply with precise phase and amplitude to maximize the beam energy boost efficiency. At the present time, analog controllers are used for all the booster supplies and the tracking waveforms are generated externally in an EPICS control unit, converted to analog signals with precision Digital-to-Analog Converters (DACs) and then distributed to all the booster power supplies with differential signal pairs. In this paper, here we propose a hybrid iterative learning control algorithm combined with discrete PID feedback controller with the objective to eliminate the signal integrity problem inherent in analogue signals, so that boosting the beam energy might become more reliable. The proposed digital controller algorithm for the TPS booster ring magnet power supply and quadruple magnet load has been simulated with success.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA130  
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WEPVA131 Single-Inductor Bipolar Outputs Power Converters 3577
 
  • Y.T. Li, C.Y. Liu, K.-B. Liu, B.S. Wangpresenter, Y.S. Wong
    NSRRC, Hsinchu, Taiwan
 
  In the circuit design for electronic products, bipolar power supply is often required. A non-isolated dual polarity power supply design is using two inductors to achieve this function. The number of inductors on the circuit would increase both the cost of products and space requirement. So the use of a single inductor bipolar power converter design can effectively reduce the cost and space to enhance product competitiveness. In this paper, the principle of a new single-inductor bipolar power converter will be described and tested to prove the feasibility of this design.  
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WEPVA132 Switching Power Supply Automatic Test System in Taiwan Photon Source 3580
 
  • Y.S. Wong, C.Y. Liu, K.-B. Liu, B.S. Wangpresenter
    NSRRC, Hsinchu, Taiwan
 
  This paper studies the use of a novel switching power supply automatic test system used in Taiwan photon source, Model 8000 is the ultimate solution for power electronic testing, the system includes a wide range of hardware choice such as AC/DC source, electronic loads, DMM, oscillate scope, noise analyzer and short/OVP tester. The ATS 8000 system uses a unique test command optimazation technology to prevent repetitive control commands from being sent to system hardware devices. This improve test speed dramatically and makes ideal choice for both high speed production applications as well as design verification.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA132  
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WEPVA134 Impedance Measurement of Vacuum Chamber Components for the Advance Photon Source (APS) Upgrade 3583
SUSPSIK052   use link to see paper's listing under its alternate paper code  
 
  • M.P. Sangroula
    IIT, Chicago, Illinois, USA
  • R.M. Lill, R.R. Lindberg, X. Sun
    ANL, Argonne, Illinois, USA
 
  Funding: U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC0206CH11357.
The proposed Advance Photon Source Upgrade (APS-U) employs a multi-bend achromat (MBA) lattice to increase the photon brightness by two to three orders of magnitude. One of the main design challenges of the upgrade is to minimize rf heating and collective instabilities associated with the impedance of small-aperture vacuum components. As part of this effort, my research focuses on impedance measurement and simulation of various MBA vacuum components. Here, we present the summary of the impedance contributions for the APS-U and describe our planned impedance measurement technique, including some measurement results for the non-evaporative getter (NEG)-coated copper chamber and simulation results for other critical components using a novel Goubau line (G-line) set up.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA134  
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WEPVA136 Vacuum System for the Diamond Light Source DDBA Upgrade 3587
 
  • M.P. Cox, M.J. Duignan, R. Howard, S.C. Lay, A.G. Miller, H.S. Shiers, A. Wolfenden
    DLS, Oxfordshire, United Kingdom
 
  One cell of the Diamond Light Source (Diamond) storage ring was upgraded in late 2016 to a Double Double Bend Achromat (DDBA) configuration to provide an additional mid-achromat insertion device straight. For practical reasons it was decided to use discrete non-evaporable getter (NEG) pumps rather than NEG coatings. This paper outlines the vacuum design of the up-grade, the reasons for the choices made and the vacuum simulation tools used as well as describing the vacuum system engineering, assembly, installation and commissioning. The measured vacuum performance is found to be in close agreement with the simulations and a simple expression is derived for the beam gas lifetime.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA136  
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WEPVA137 Progress on the Design of the Storage Ring Vacuum System for the Advanced Photon Source Upgrade Project 3590
 
  • B.K. Stillwell, B. Billett, B. Brajuskovic, J.A. Carter, E.S. Kirkus, M.A. Lale, J.E. Lerch, J. R. Noonan, M.M. O'Neill, B.G. Rocke, K.J. Suthar, D.R. Walters, G.E. Wiemerslage, J. Zientek
    ANL, Argonne, Illinois, USA
 
  Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Recent work on the design of the storage ring vacuum system for the Advanced Photon Source Upgrade project (APS-U) includes: revising the vacuum system design to accommodate a new lattice with reverse bend magnets, modifying the designs of vacuum chambers in the FODO sections for more intense incident synchrotron radiation power, modifying the design of rf-shielding bellows liners for better performance and reliability, modifying photon absorber designs to make better use of available space, and integrated planning of components needed in the injection, extraction, and rf cavity straight sections. An overview of progress in these areas is presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA137  
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WEPVA138 The RaDIATE High-Energy Proton Materials Irradiation Experiment at the Brookhaven Linac Isotope Producer Facility 3593
 
  • K. Ammigan, P. Hurhpresenter, R.M. Zwaska
    Fermilab, Batavia, Illinois, USA
  • A. Amroussia, C.J. Boehlert
    Michigan State University, East Lansing, Michigan, USA
  • M.S. Avilov, F. Pellemoine
    FRIB, East Lansing, USA
  • M. Calviani, E. Fornasiere, A. Perillo-Marcone, C. Torregrosa
    CERN, Geneva, Switzerland
  • A.M. Casella, D.J. Senor
    PNNL, Richland, Washington, USA
  • C.J. Densham
    STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
  • T. Ishida, S. Makimura
    KEK, Ibaraki, Japan
  • V.I. Kuksenko, S.G. Roberts
    University of Oxford, Oxford, United Kingdom
  • Y. Lee, T.J. Shea, C.A. Thomas
    ESS, Lund, Sweden
  • L.F. Mausner, D. Medvedev, N. Simos
    BNL, Upton, Long Island, New York, USA
  • E. Wakai
    KEK/JAEA, Ibaraki-Ken, Japan
 
  Funding: Work supported by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
The RaDIATE collaboration (Radiation Damage In Accelerator Target Environments) was founded in 2012 to bring together the high-energy accelerator target and nuclear materials communities to address the challenging issue of radiation damage effects in beam-intercepting materials. Success of current and future high intensity accelerator target facilities requires a fundamental understanding of these effects including measurement of materials property data. Toward this goal, the RaDIATE collaboration organized and carried out a materials irradiation run at the Brookhaven Linac Isotope Producer facility (BLIP). The experiment utilized a 181 MeV proton beam to irradiate several capsules, each containing many candidate material samples for various accelerator components. Materials included various grades/alloys of beryllium, graphite, silicon, iridium, titanium, TZM, CuCrZr, and aluminum. Attainable peak damage from an 8-week irradiation run ranges from 0.03 DPA (Be) to 7 DPA (Ir). Helium production is expected to range from 5 appm/DPA (Ir) to 3,000 appm/DPA (Be). The motivation, experimental parameters, as well as the post-irradiation examination plans of this experiment are described.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA138  
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WEPVA140 Design Studies and Optimization of High-Field Nb3Sn Dipole Magnets for a Future Very High Energy pp Collider 3597
 
  • V.V. Kashikhin, I. Novitski, A.V. Zlobin
    Fermilab, Batavia, Illinois, USA
 
  Funding: Work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy
High filed accelerator magnets with operating fields of 15-16 T based on the Nb3Sn superconductor are being considered for the LHC energy upgrade or a future Very High Energy pp Collider. Magnet design studies are being conducted in the U.S., Europe and Asia to explore the limits of the Nb3Sn accelerator magnet technology while optimizing the magnet design and performance parame-ters, and reducing magnet cost. The first results of these studies performed at Fermilab in the framework of the US-MDP are reported in this paper.
 
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WEPVA141 Ion Cyclotron Resonance Heating Transmitter Opening Switch Upgrade 3600
 
  • M.P.J. Gaudreau, M.K. Kempkespresenter, J. Kinross-Wright, R.E. Simpson
    Diversified Technologies, Inc., Bedford, Massachusetts, USA
 
  Diversified Technologies Inc. (DTI) has installed a high-power solid-state opening switch upgrade package to replace the mercury ignitron crowbars in the Ion Cyclotron Resonance Heating (ICRH) Transmitters at MIT Plasma Fusion Science Center's (PFSC) Alcator C Mod, a Tokamak-type fusion experimental device. The speed of the series opening switch avoids the large fault currents on the transformer and power feed inherent with a crowbar. This improvement enables re-optimization of the Transformer/Rectifier (T/R) set, ultimately allowing increased power output and increased tetrode reliability. The ratings of the prior high voltage power supply are a compromise between high output power (lower impedance required from the T/R set) and crowbar reliability (higher impedance required from the power supply to limit fault current). DTI's opening switch upgrade safely allows the use of significantly reduced transformer impedance and lower droop, giving increased power as well as improved tube protection. DTI's opening switch kit can readily be adapted to any similar transmitters as an upgrade from a crowbar.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA141  
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WEPVA142 Active Compensation Coils in the Fermilab g-2 Experiment 3602
 
  • K.E. Badgley
    Texas A&M University, College Station, USA
  • B. Kiburg
    Fermilab, Batavia, Illinois, USA
  • M.W. Smith
    University of Washington, CENPA, Seattle, USA
 
  The recently commissioned Fermilab muon g-2 experiment is aiming to determine the anomalous magnetic moment of the muon to 140 ppb. To achieve this level of precision, the magnetic field seen by the muon must be know at fraction of a ppm level, which puts limits on the required magnetic field uniformity. In addition to the mechanical adjustments made to magnet pole tips, a set of 200 trim coils were added to the ring. These coils form concentric rings with 100 on the top pole and 100 on the bottom. Measurements of the remaining integrated filed errors were made using NMR probes. The use of these trim coils to reduce the remaining higher order field errors will be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA142  
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WEPVA143 Cooling-down and Cooling of Superconducting Magnets at 4.5K with Very Little Liquid Helium using Coolers* 3606
 
  • M.A. Green, S. Chouhan
    FRIB, East Lansing, USA
 
  Funding: This work is supported in part by a grant from the National Science Foundation. The Michigan State University grant number is PHY0958726.
Because liquid helium is often in short supply, it is often difficult to get helium for cooling superconducting magnets that are too large to be cryogen free magnets. Grade A helium is often available in high-pressure bottles, but not in large quantities. This report describes how one can cool-down and maintain a constant temperature of ~4.5 K in a superconducting magnet that has less than 5 L of liquid in the cryostat once it has been filled with liquid helium. One can do this with either GM coolers in the drop-in mode with pulsed tube coolers. The number of coolers needed to cool the magnet depends to the heat load at 4.5 K and the desired cool-down time for the magnet system. This type of cooling system is suitable for magnets that are away from a conventional large helium refrigeration system. Examples are S/C insertion (wigglers and undulators), spectrometer magnets, and ECR ion source magnets.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA143  
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WEPVA145 Analysis of Mean Free Path and Field Dependent Surface Resistance 3609
 
  • J.T. Maniscalco, F. Furuta, D.L. Hallpresenter, P.N. Koufalis, M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: NSF-PHY 1416318
Work from Cornell in 2016 built on recent theoretical research in the field of SRF to link the electron mean free path to the field-dependent BCS surface resistance. This research relates the magnitude of the ‘‘anti-Q-slope'', the puzzling reduction of surface resistance with increasing RF field intensity observed in certain cavities, to the doping level of nitrogen-doped niobium, quantified by the mean free path: shorter mean free paths correspond directly with stronger anti-Q-slopes. The theoretical connection comes through the overheating of the quasiparticles, which more effectively transfer their energy to the lattice at short mean free paths. In this report, we present an update of this analysis, investigating recent test results of low-temperature-doped single-cell and nine-cell cavities. We also study the theoretical implications for cavities at frequencies higher and lower than the often-studied 1.3~GHz.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA145  
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WEPVA146 Vacuum System Design and Simulation for CHESS-U 3612
 
  • Y. Li, S.T. Barrett, D.C. Burke, J.V. Conway, X. Liu, A. Lyndaker
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: This work is supported by National Science Foundation Reward #DMR-1332208
A major upgrade project (dubbed CHESS-U) is planned to elevate performance of Cornell High Energy Synchrotron Source (CHESS) to the state-of-art 3rd generation light sources. In the project, about 80-m of Cornell Electron Storage Ring (CESR) will be replaced with double-bend achromat (DBA) lattice to reduce electron beam emittance. In this presentation, we will describe designs of the CHESS-U vacuum system, including new beam pipe extrusions and chambers, sliding joints, and crotch absorbers. Vacuum pumping system consists of distributed pumps (in the form of NEG strips) in the dipole chambers, and compact discrete NEG/Ion pumps in the quad straight and undulator beampipes. MolFlow+ is used to evaluate pumping performances of the CHESS-U vacuum system. First, we demonstrate that the planned vacuum pumping system can achieve and sustain required ultra-high vacuum level in CHESS-U operations, after an initial beam conditioning. Second, we will explore beam commissioning processes of the new vacuum chambers, and simulate the saturation of the NEG strips during the commissioning. These simulations will aid continuing design optimization for the CHESS-U vacuum pumping system.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA146  
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WEPVA147 Iron-Free Detector System for the Linear Collider with Multiple Return Solenoids 3615
 
  • A.A. Mikhailichenko
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  We investigate the Iron-free magnetic system for implementation in a detector for future Linear Collider. One peculiarity is in usage of many small-diameter solenoids for the flux return. Machine-detector interface is discussed also.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA147  
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WEPVA148 Dynamics of Target Motion Under Exposure of Hard Gamma Undulator Radiation 3618
 
  • A.A. Mikhailichenko
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  We describe time dependent dynamics of the target motion under exposure by undulator radiation in a system for positron production. We took into account inertia of material of target. Calculations carried with help of FlexPDE code.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA148  
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WEPVA150 New Controller for High Voltage Converter Modulator at Spallation Neutron Source 3621
 
  • D.L. Brown, X. Geng, S.W. Lee, M. Wezensky, A.P. Zhukov
    ORNL, Oak Ridge, Tennessee, USA
 
  Funding: This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy.
We have developed a new control system for the high voltage converter modulator at the Spallation Neutron Source to replace the original control system designed by Los Alamos National Laboratory which is approaching obsolescence. The new controller, based on national instruments PXI/FlexRIO FPGA hardware, offers enhancements over the original system such as modular construction, flexibility and non-proprietary software. The new controller also provides new capabilities like modulator pulse flattening, waveform capture & first fault detection. This paper will discuss the design of the system, including the human machine interface, based on lessons learned at the Spallation Neutron Source and other projects. It will also discuss performance and other issues related to operation in an accelerator facility which requires high availability. To date half of the high voltage converter modulators have been upgraded with the new controller with the remainder scheduled for completion by mid-2017.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA150  
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WEPVA151 The eRHIC Interaction Region Magnets 3624
 
  • B. Parker, R.B. Palmer, H. Witte
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
Designing eRHIC Interaction Region (IR) magnets faces special Machine Detector Interface challenges. Based upon HERA-II experience, a fundamental consideration is to avoid excessive background due to synchrotron radiation striking masks and septa in the vicinity of the experiment. Circumventing such radiation is problematic because the colliding beams have quite different rigidities; we must shield the e-beam from hadron IR magnet multi-tesla coil fields. On the outgoing-hadron, i.e. forward IR side, this difficulty is compounded by needing large hadron beam apertures to enable downstream separation and experimental detection of a mix of scattered and produced forward going charged particles and (in the electron-ion case) a wide-spread cone of neutrons. Here we present superconducting magnet designs with combinations of active and passive shielding and Sweet Spot coils to meet these requirements along with the design of a superferric spectrometer dipole, with an integrated cancel coil, that extends the forward experimental acceptance.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA151  
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