Keyword: resonance
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MOPAB015 Optimization of a Skew Parametric Resonance Ionization Cooling Channel Using Genetic Algorithm optics, controls, dipole, collider 111
 
  • Y. Bao
    UCR, Riverside, California, USA
  • A. Afanasev
    GWU, Washington, USA
  • Y.S. Derbenev, V.S. Morozov, A.V. Sy
    JLab, Newport News, Virginia, USA
  • R.P. Johnson
    Muons, Inc, Illinois, USA
  
  Funding: This work is supported by Muons Inc.
Skew Parametric-resonance Ionization Cooling (Skew PIC) is designed for the final 6D cooling of a high-luminosity muon collider. Tracking of muons in such a channel has been modeled in MADX and matter-dominated simulation tool G4beanline in previous studies. In this work, we developed an optimization code based on Genetic Algorithm (GA). We optimized the cooling channel and increased the acceptance of the channel by using the GA code. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB015  
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MOPAB126 Applications of Metamaterials for Particle Beam Diagnostics target, radiation, electron, diagnostics 425
 
  • T.G. Vaughan, P. Karataev
    JAI, Egham, Surrey, United Kingdom
  • V. Antonov
    Royal Holloway, University of London, Surrey, United Kingdom
  • V.V. Soboleva
    RASA Center in Tomsk, Tomsk, Russia
  
  Funding: The work was supported by the Leverhulme Trust through the International Network Grant (IN-2015-012) and the European Union Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 655179 and Russian Governmental Program 'Nauka', N: 0.1656.2016.
Modern and future accelerators, such as linear colliders and X-ray Free Electron Lasers (X-FELs), will be capable of producing femtosecond and sub-femtosecond electron bunches with unprecedented intensity. Non-invasive beam diagnostics will be an integral component of such machines. A new non-destructive method, which employs a Left Handed Metamaterial (LHM), is promising as it provides additional flexibility in the generation and manipulation of radiation compared to techniques which use conventional materials. Simulations of the interaction of a photon beam with the LHM target have been performed using CST Microwave Studio. The range over which the frequency responce is negative can be tuned to the bunch length requirements by varying the parameters of the unit cell such as: the dimensions of the rings and the number of slits in each ring. Simulations have also been performed using Particle Studio on the interaction of an electron beam with the LHM. With a flexible resonance in the terahertz range, this material not only offers applications for ultra short bunch length measurements, but it also opens up the possibility to be used to generate coherent terahertz radiation. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB126  
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MOPIK092 Computer Modelling of the SC202 Superconducting Cyclotron for Hadron Therapy simulation, cyclotron, extraction, proton 742
 
  • O. Karamyshev, V. Malinin, D.V. Popov
    JINR/DLNP, Dubna, Moscow region, Russia
  • Y.F. Bi, G. Chen, K.Z. Ding, Y. Song
    ASIPP, Hefei, People's Republic of China
  • G.A. Karamysheva, N.A. Morozov, E.V. Samsonov, G. Shirkov, S.G. Shirkov
    JINR, Dubna, Moscow Region, Russia
  
  The SC202 superconducting cyclotron for hadron therapy is under development by collaboration of ASIPP (Hefei, China) and JINR (Dubna, Russia). The accelerator will provide about 200 MeV proton beam with maximum current of 1μA in 2017-2018. We have performed simulations of all systems of the SC202 cyclotron and specified the main parameters of magnet, acceleration system and extraction elements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK092  
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MOPIK119 Beam Dynamics in g-2 Storage Ring storage-ring, experiment, quadrupole, dipole 817
 
  • W. Wu, B. Quinn
    UMiss, University, Mississippi, USA
  
  The muon anomalous magnetic moment has played an important role in constraining physics beyond the Standard Model. The Fermilab Muon g-2 Experiment has a goal to measure it to unprecedented precision: 0.14 ppm. To achieve this goal, we must understand the beam dynamics systematic effects in the muon storage ring. We will present the muon beam dynamics and discuss two specific topics here: the beam resonance which is related to the muon loss and the fast rotation analysis to determine the muon momentum distribution.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK119  
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MOPVA018 Resonant Coherent Diffraction Radiation System at ERL Test Accelerator in KEK cavity, radiation, experiment, emittance 887
 
  • Y. Honda, A. Aryshev, R. Kato, T. Miyajima, T. Obina, M. Shimada, R. Takai, N. Yamamoto
    KEK, Ibaraki, Japan
  
  Funding: This work was supported by JSPS KAKENHI Grant Number 16H05991
An Energy Recovery Linac can produce a low emittance and short bunch beam at a high repetition rate. A test accelerator, compact-ERL, has been operating in KEK for development works of technologies related to ERL and CW-Superconducting accelerators. In a special beam operation mode of bunch compression, a short bunch beam of ~150 fs at the repetition rate of CW 1.3 GHz can be realized in the return-loop. One of the promising applications of such a short bunch beam is a high power THz radiation source produced by a coherent radiation. When a charged particle beam passes close to a conductive target, a radiation called diffraction radiation is produced. If the target mirrors form an optical cavity which fundamental frequency matches the repetition frequency of the beam, the radiation resonates in the cavity, resulting in extracting a huge radiation power determined by the loss of the cavity. We plan to perform an experiment of the resonant coherent diffraction mechanism in the return-loop of the compact-ERL to test the feasibility to be a wide band high power THz source. We report the design of the experimental setup to be installed in the summer of 2017. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA018  
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MOPVA052 Study on HOM Power Levels in the BESSY VSR Module HOM, cavity, SRF, operation 982
 
  • A.V. Tsakanian, H.-W. Glock, J. Knobloch, A.V. Vélez
    HZB, Berlin, Germany
  
  The BESSY VSR upgrade of the BESSY II light source represents a novel approach to simultaneously store of long (ca. 15ps) and short (ca. 1.5ps) bunches in the storage ring with the 'standard' user optics. This challenging goal requires installation of four new SRF cavities (2x1.5GHz and 2x1.75GHz) in a single module to minimize space requirements. These cavities are equipped with strong waveguide and beam tube HOM dampers necessary for stable operation. The expected HOM power and spectrum has been analyzed for the complete module. This study is performed for various BESSY VSR bunch filling patterns with 300 mA beam current. In the module different cavity arrangements are analyzed to reach the optimal operation conditions with equally distributed power portions in warm HOM loads and tolerable beam coupling impedance.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA052  
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MOPVA071 Press Forming Tests of Superconducting Spoke Cavity for Laser Compton Scattered Photon Sources cavity, laser, photon, niobium 1031
 
  • M. Sawamura, R. Hajima
    QST, Tokai, Japan
  • H. Hokonohara, Y. Iwashita, H. Tongu
    Kyoto ICR, Uji, Kyoto, Japan
  • T. Kubo, T. Saeki
    KEK, Ibaraki, Japan
  
  We are developing the superconducting spoke cavity for laser Compton scattered (LCS) photon sources. We adopt the superconducting spoke cavity for electron beam drivers to realize a wide use of LCS X-ray and '-ray sources in academic and industrial applications. The spoke cavity can make the accelerator more compact than an elliptical cavity because the cavity size is small at the same frequency and the packing factor is good by installing couplers on outer conductor. Though our proposal design for the photon source consists of the 325 MHz spoke cavities in 4K operation, we are fabricating the half scale model of 650 MHz spoke cavity in order to accumulate our cavity production experience by effective utilization of our limited resources. Since the spoke has more complicated structure than an elliptical cavity, we performed press forming tests for the half spoke and estimated the formed shapes with 3-dimensional measurement.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA071  
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TUPAB147 The Final RF-Design of the 36 MHz-HSI-RFQ-Upgrade at GSI rfq, simulation, multipole, alignment 1678
 
  • M. Baschke, H. Podlech
    IAP, Frankfurt am Main, Germany
  • L. Groening, S. Mickat, C. Zhang
    GSI, Darmstadt, Germany
  
  In Darmstadt/Germany the existing accelerator cite GSI is expanding to one of the biggest joint research projects worldwide: FAIR, a new antiproton and ion research facility with so far unmatched intensities and quality. The existing accelerators will be used as pre-accelerators and therefor need to be upgraded to fulfill the requirements with respect for intensity and beam quality. In a first step the 9.2 m long 36 MHz-HSI-RFQ for high current beams will obtain new electrodes to reach the specific frequency and to allow a higher electric strength. Therefor several simulations with CST MWS have been done. The final RF-design will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB147  
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TUPAB148 Investigation of a Splitring-RFQ for High Current Ion Beams at Low Frequencies rfq, impedance, simulation, ion 1680
 
  • M. Baschke, H. Podlech, A. Schempp
    IAP, Frankfurt am Main, Germany
  
  For hadron linacs RFQs are the first stage of acceleration. To reach high intensities a new Splitring-RFQ is investigated. Not only a high current and high beam quality/brilliance should be achieved, also a good tuning flexibility and comfort for maintenance are part of the study. It will consist of two stages with 27 MHz and 54 MHz to accelerate ions with an A/q of 60 up to energies of 200 keV/u. Therefor RF simulations with CST MWS were done to study the quality factor and the shunt impedance as well as tuning possibilities. First results and the status of the project will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB148  
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TUPIK052 Fast Automatic Ramping of High Average Power Guns cavity, gun, operation, feedback 1809
 
  • Y. Renier
    DESY Zeuthen, Zeuthen, Germany
  • M.K. Grecki, O. Hensler, S. Pfeiffer
    DESY, Hamburg, Germany
  
  The electron guns at PITZ, FLASH and European XFEL are standing wave structures which operate at high average power (>40 kW) to produce long trains of high quality beams. This amount of power heats the cavity surface enough to change signi'cantly the gun resonance frequency. As consequence, to keep the re'ection low, the RF power ramp must be enough slow to permit the water cooling system to keep the gun temperature close to the set-point. Also, as the temperature probe sits close to the surface of the iris, the required gun temperature set-point to maintain the gun on resonance is a function of the average power. The RF power ramping is a difficult process in which temperature and re'ection must be monitored to adjust accordingly the temperature set-point and the ramping speed of the RF power. An automatic software to adjust the RF frequency and the temperature set-point of the PITZ gun in parallel to the RF power ramping has been developed. The use of this software has signi'cantly reduced the time spent to start up the gun or to recover from interlocks, increasing the time spent at nominal parameters which would also be very important for user facilities.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK052  
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TUPVA026 Beam-Beam Studies for FCC-hh optics, simulation, dynamic-aperture, luminosity 2109
 
  • J. Barranco García, T. Pieloni, C. Tambasco
    EPFL, Lausanne, Switzerland
  • X. Buffat, S.V. Furuseth, C. Tambasco
    CERN, Geneva, Switzerland
  • S.V. Furuseth
    NTNU, Trondheim, Norway
  
  Funding: This works was performed in the framework of the European Circular 'Energy Fr'ontier Collider Study, H2020 Framework Programme under grant agreement no. 654305. We acknowledge support from the Swiss State Secretariat for Education, Research and Innovation SERI.
The Future Circular Collider hadron-hadron (FCC-hh) design study is currently exploring different IR design possibilities including round and flat optics or different crossing schemes. The present study intends to evaluate each scenario from the beam-beam effects point of view. In particular the single particle long term stability to maximize beam lifetimes and luminosity reach is used to quantify the differences. The impact of strong head on interactions on the beam quality and lifetime is addressed by means of GPU accelerated simulations code featuring a weak-strong 6-dimensional beam-beam interaction. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA026  
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TUPVA027 Study of Beam-Beam Long Range Compensation with Octupoles octupole, optics, dynamic-aperture, beam-beam-effects 2113
 
  • T. Pieloni, J. Barranco García, C. Tambasco
    EPFL, Lausanne, Switzerland
  • X. Buffat, C. Tambasco
    CERN, Geneva, Switzerland
  
  Funding: The European Circular Energy-Frontier Collider Study (EuroCirCol), EU's Horizon 2020 grant No 654305.
Long range beam-beam effects are responsible for particle losses and define fundamental operational parameters of colliders (i.e. crossing angles, intensities, emittances, β*). In this study we propose octuple magnets as a possible scheme to efficiently compensate long-range beam-beam interactions with a global correction scheme. The impact and improvements on the dynamic aperture of colliding beams together with estimates of the luminosity potentials are discussed for the HL-LHC upgrade and extrapolations made for the FCC project. Results are compared to other compensating schemes. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA027  
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TUPVA045 Compensation of Head-on Beam-Beam Induced Resonance Driving Terms and Tune Spread in the Relativistic Heavy Ion Collider electron, lattice, proton, optics 2171
 
  • W. Fischer, X. Gu, C. Liu, Y. Luo, A. Marusic, R.J. Michnoff, T.A. Miller, M.G. Minty, C. Montag, A.I. Pikin, G. Robert-Demolaize, V. Schoefer, P. Thieberger
    BNL, Upton, Long Island, New York, USA
  • S.M. White
    ESRF, Grenoble, France
  
  Funding: Work supported by U.S. DOE under contract No DE-AC02-98CH10886 with the U.S. Department of Energy.
A head-on beam-beam compensation scheme was implemented for operation in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. The compensation consists of a lattice for the minimization of beam-beam driven resonance driving terms, and electron lenses for the reduction of the beam-beam induced tune spread. We describe the implementations of the lattice and electron lenses, and report on measurements of lattice properties and the effect of the electron lenses on the hadron beam. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA045  
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TUPVA050 RHIC Polarized Proton Operation for 2017 lattice, polarization, injection, luminosity 2188
 
  • V.H. Ranjbar, P. Adams, Z. Altinbas, E.C. Aschenauer, G. Atoian, E.N. Beebe, S. Binello, I. Blackler, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, M.R. Costanzo, T. D'Ottavio, K.A. Drees, P.S. Dyer, A.V. Fedotov, W. Fischer, C.J. Gardner, D.M. Gassner, X. Gu, C.E. Harper, M. Harvey, T. Hayes, J. Hock, H. Huang, R.L. Hulsart, J.P. Jamilkowski, T. Kanesue, N.A. Kling, J.S. Laster, C. Liu, Y. Luo, D. Maffei, M. Mapes, G.J. Marr, A. Marusic, F. Méot, K. Mernick, R.J. Michnoff, T.A. Miller, M.G. Minty, C. Montag, J. Morris, G. Narayan, C. Naylor, S. Nemesure, P. Oddo, M. Okamura, S. Perez, A.I. Pikin, A. Poblaguev, S. Polizzo, V. Ptitsyn, D. Raparia, G. Robert-Demolaize, T. Roser, J. Sandberg, W.B. Schmidke, V. Schoefer, F. Severino, T.C. Shrey, K.S. Smith, Z. Sorrell, D. Steski, S. Tepikian, R. Than, P. Thieberger, J.E. Tuozzolo, G. Wang, K. Yip, A. Zaltsman, A. Zelenski, K. Zeno, W. Zhang, B. van Kuik
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by the US Department of Energy under contract number DE-SC0012704
The 2017 operation of the Relativistic Heavy Ion Collider (RHIC) involved the running of only a single experiment at STAR with PHENIX offline in the process of the upgrade to sPHENIX. For this run there were several notable changes to machine operations. These included, transverse polarization, luminosity leveling, a new approach to machine protection and the development of new store and ramped lattices. The new 255 GeV store lattice was designed to both accommodate the necessary phase advance between the e-lens and IP8 for testing and to maximize dynamic aperture. The new lattices on the ramp were designed to maximize polarization transmission during the three strong intrinsic spin resonances crossings. Finally we are also commissioning new 9 MHz RF cavities during this run. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA050  
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TUPVA063 RF Tuning Tests on the Coupled FRANZ RFQ-IH-DTL rfq, DTL, coupling, cavity 2224
 
  • A. Almomani, U. Ratzinger
    IAP, Frankfurt am Main, Germany
  • M. Heilmann
    GSI, Darmstadt, Germany
  
  The neutron beam at the FRANZ facility will be produced by the 7Li(p, n)7Be reaction using an intense 2 MeV proton beam. These protons will be accelerated from 120 keV to 2 MeV by a coupled 4-Rod-type RFQ and a 8 gap interdigital H-type structure (IH-DTL). This coupled RFQ-IH-cavity will be operated at 175 MHz in cw mode and it has a total length of about 2.3 m. The two structures (RFQ, IH-DTL) are internally coupled inductively, and consequently only one RF-amplifier providing a total power up to 250 kW is needed for operation. The IH-DTL is RF tuned together with an Al-RFQ model, before final IH-DTL installation in the FRANZ cave, while the original RFQ was already installed in the beam line. After RF power and beam tests the coupled structure will be installed and continued with RF and beam. This paper will be focused on the RF tuning process and the main results will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA063  
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TUPVA092 An Upgrade Scenario of RF System to Achieve 1.6 MW Beam Acceleration in J-PARC RCS cavity, power-supply, acceleration, impedance 2297
 
  • M. Yamamoto, M. Nomura, T. Shimada, F. Tamura
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • K. Hara, K. Hasegawa, C. Ohmori, Y. Sugiyama, M. Yoshii
    KEK, Tokai, Ibaraki, Japan
  
  The J-PARC RCS has successfully accelerated 1 MW equivalent proton beam. However, the beam commissioning results and the particle tracking simulation suggest that the RCS has possibility to accelerate up to 1.6 MW beam. Since the power supply of the rf system almost reaches the limit under the condition of 1 MW beam, we consider the possible upgrade scenario of the rf system to accelerate 1.6 MW beam.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA092  
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TUPVA112 Acceleration of Polarized Proton and Deuteron Beams in Nuclotron at JINR proton, acceleration, polarization, betatron 2349
 
  • Y. Filatov, A.V. Butenko, A.D. Kovalenko, V.A. Mikhaylov
    JINR, Dubna, Moscow Region, Russia
  • Y. Filatov
    MIPT, Dolgoprudniy, Moscow Region, Russia
  • A.M. Kondratenko, M.A. Kondratenko
    Science and Technique Laboratory Zaryad, Novosibirsk, Russia
  
  The superconducting synchrotron Nuclotron allows one to accelerate proton and deuteron beams up to 13.5 GeV/c. The beam depolarization occurs at the crossing of spin resonances. For deuterons, the vertical polarization is preserved almost to the maximum momentum. Tens of spin resonances are crossing during the proton acceleration. The proton polarization will be preserved by a solenoidal 5% snake up to 3.4 GeV/c at the field ramp rate of 1 T/s. It is planned to use a partial 50% snake to eliminate the resonant depolarization of the proton beam in the total momentum range of the accelerator. The results of simulations and experimental data are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA112  
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WEOAA3 Realizing a High-Intensity Low-Emittance Beam in the J-PARC 3-GeV RCS emittance, injection, sextupole, extraction 2470
 
  • H. Hotchi, H. Harada, S. Kato, K. Okabe, P.K. Saha, Y. Shobuda, F. Tamura, N. Tani, Y. Watanabe, M. Yoshimoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  
  The J-PARC 3-GeV rapid cycling synchrotron (RCS) has two functions; one as a proton driver to produce pulsed muons and neutrons, and the other as an injector to the following 50-GeV main ring (MR). RCS is now intensively developing a high-intensity beam test to realize a high-intensity low-emittance beam with less beam halo required from MR. This paper presents the recent experimental results, together with detailed discussions for the emittance growth and its mitigation mechanisms.  
slides icon Slides WEOAA3 [1.732 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEOAA3  
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WEXB1 Studies and Observations of Beam Dynamics Near a Sum Resonance space-charge, synchrotron, emittance, simulation 2503
 
  • G. Franchetti
    GSI, Darmstadt, Germany
  • S.S. Gilardoni, A. Huschauer, F. Schmidt, R. Wasef
    CERN, Geneva, Switzerland
  
  The effect of space charge on bunches stored for long term in a can be severe for beam survival. This may be the case in projects as SIS100 at GSI or LIU at CERN. In the past decade systematic simulation studies and experiments performed at CERN and GSI have highlighted the space charge induced periodic crossing of “one dimensional” resonances as the underlying mechanism of long term beam loss or emittance growth. However only in 2012, for the first time, the effect of space charge on a normal third order coupled resonance was investigated at the CERN-PS. The experimental results have highlighted an unprecedented asymmetric beam response where in the horizontal plane the beam exhibits a thick halo, whereas the vertical profile has only core growth. The quest for explaining these results requires a journey thorough the 4 dimensional dynamics of the coupled resonance investigating the fix-lines, and requires a detailed code-experiment benchmarking also including beam profile benchmarking. This study shows that the experimental results of the 2012 PS measurements can be explained by the dynamics the fixed lines also including the effect of the dispersion.  
slides icon Slides WEXB1 [18.195 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEXB1  
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WEPAB006 Performance Improvements of the BESSY II Storage Ring by Optimizing the Phase Acceptance injection, sextupole, storage-ring, optics 2571
 
  • P. Kuske, J. Li
    HZB, Berlin, Germany
  
  Linear optics modifications in order to improve injec-tion efficiency and for the installation of two IDs in one straight section demand an optimization of the sextupole correction scheme. Four harmonic sextupole families were sufficient with the earlier 8-fold symmetric lattice. Today there are ten families of harmonic sextupole mag-nets in addition to the three families of chromatic sextu-poles. This paper describes our experimental approach to find better settings for these harmonic sextupoles based on the direct optimization of the injection efficiency with a longitudinal phase offset between storage ring and the injector - in our case a booster synchrotron. As demon-strated in the paper, the resulting improvement of the phase acceptance of the ring leads to increased momen-tum acceptance by suppressing 3rd order non-systematic resonances. This increases not only the injection effi-ciency for long bunches but also the Touschek lifetime, the largest contribution to the overall lifetime of low emittance storage rings.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB006  
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WEPAB011 High Order Magnetic Field Components and Non-Linear Optics at the ANKA Storage Ring wiggler, octupole, sextupole, betatron 2586
 
  • A.I. Papash, E. Blomley, J. Gethmann, E. Huttel, A.-S. Müller, M. Schuh
    KIT, Eggenstein-Leopoldshafen, Germany
  
  The Karlsruhe Institute of technology operates the 2.5 GeV electron storage ring ANKA as an accelerator test facility and synchrotron radiation source. A superconducting wiggler is installed in a short straight section of the ring where vertical beta-function is large (13 m). The life time of the electron beam was reduced from 15 to 12 hours at a high field level of the wiggler (2.5 T) even though the coherent shift of vertical tune was compensated locally. Computer simulations show the non-linear nature of the effect. The ANKA storage ring operates with strong sextupoles at a positive chromaticity of +2/+6. Even residual octupole components of the wiggler field, set at the tolerance limit of fabrication conditions, could reduce the dynamic aperture for off-momentum particles providing the betatron tune is located in the vicinity of a weak octupole resonance and the chromaticity is high. Also the vertical betatron tune is close to the sextupole resonance Qy=8/3. Large resonance stop-band and proximity of sextupole resonance affect the life time as well. Betatron tunes of ANKA have been shifted away of suspected high-order resonances and beam life time was essentially improved.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB011  
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WEPAB055 Characterizing the Nonlinear Performance of a DLSR With the Effective Acceptance of the Bare Lattice lattice, sextupole, storage-ring, emittance 2706
 
  • Y. Jiao, Z. Duan, G. Xu
    IHEP, Beijing, People's Republic of China
  
  Funding: Work supported by NSFC (11475202, 11405187, 11605212)
In a diffraction-limited storage ring (DLSR) light source, associated with the strong focusing and sextu-poles, the detuning terms are large and integer and half integer resonances can be reached at small momentum deviation and transverse amplitudes. We propose to use the effective ring acceptances of the bare lattice to characterize the nonlinear performance of the actual ring, by considering the limiting effects of integer and half integer resonances on beam dynamics. Such a concept will be very useful in lattice design of a DLSR light source. In this paper, we will discuss the reasoning, verification, and application range of this definition. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB055  
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WEPAB069 Possible Suppression of Head-Tail Instability by a Feedback Kicker for a Light Source Without Any Sextupole sextupole, storage-ring, emittance, dynamic-aperture 2738
 
  • T.-Y. Lee, B.H. Oh
    PAL, Pohang, Kyungbuk, Republic of Korea
  
  As storage ring based light sources pursue as low emittance as possible down to the diffraction limited number by adopting as many bending magnets and quadrupoles in a cell, the number of sextupole magnets required to correct chromaticity and secure a sufficiently big dynamic aperture grows substantially. As a result, the circumference of a multi-bend achromatic lattice storage ring is typically very long. This paper discusses over a possible scheme to run a storage ring without sextupole magnets at all and suppress the head-tail instability by using a transverse feedback kicker.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB069  
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WEPIK022 CEPC Booster Lattice Design lattice, dynamic-aperture, collider, booster 2968
 
  • T.J. Bian, X. Cui, J. Gao, C. Zhang
    IHEP, Beijing, People's Republic of China
  
  In September 2012, Chinese scientists proposed a Circular Electron Positron Collider(CEPC) at 240 GeV centre of mass for Higgs studies. The CEPC booster(CEPCB) provides 120 GeV electron and positron beams to the CEPC collider for top-up injection. We foucus on the beam dynamic study for CEPCB and analyse the key point of CEPCB lattice design. In this paper, a lattice design with good dynamic aperture is proposed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK022  
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WEPIK038 Acceleration of Polarized Protons and Deuterons in the Ion Collider Ring of JLEIC collider, ion, polarization, proton 3014
 
  • V.S. Morozov, Y.S. Derbenev, F. Lin, Y. Zhang
    JLab, Newport News, Virginia, USA
  • Y. Filatov
    MIPT, Dolgoprudniy, Moscow Region, Russia
  • A.M. Kondratenko, M.A. Kondratenko
    Science and Technique Laboratory Zaryad, Novosibirsk, Russia
  
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contracts No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
The figure-8-shaped ion collider ring of Jefferson Lab Electron-Ion Collider (JLEIC) is transparent to the spin. It allows one to preserve proton and deuteron polarizations using weak stabilizing solenoids when accelerating the beam up to 100 GeV/c. When the stabilizing solenoids are introduced into the collider's lattice, the particle spins precess about a spin field, which consists of the field induced by the stabilizing solenoids and the zero-integer spin resonance strength. During acceleration of the beam, the induced spin field is maintained constant while the resonance strength experiences significant changes in the regions of interference peaks. The beam polarization depends on the field ramp rate of the arc magnets. Its component along the spin field is preserved if acceleration is adiabatic. We present the results of our theoretical analysis and numerical modeling of the spin dynamics during acceleration of protons and deuterons in the JLEIC ion collider ring. We demonstrate high stabil-ity of the deuteron polarization in figure-8 accelerators. We analyze a change in the beam polarization when crossing the transition energy. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK038  
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WEPIK052 Energy Acceptance and on Momentum Aperture Optimization for the Sirius Project lattice, storage-ring, betatron, dynamic-aperture 3041
 
  • P.S. Dester, L. Liu, F.H. de Sá
    LNLS, Campinas, Brazil
  
  A fast objective function to calculate Touschek lifetime and on momentum aperture is essential to explore the vast search space of strength of quadrupole and sextupole families in Sirius. Touschek lifetime is estimated by using the energy aperture (dynamic and physical), rf system parameters and driving terms. Non-linear induced betatron oscillations are considered to determine the energy aperture. On momentum aperture is estimated by using a chaos indicator and resonance crossing considerations. Touschek lifetime and on momentum aperture constitute the objective function, which was used in a multi-objective genetic algorithm to perform an optimization for Sirius.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK052  
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WEPIK074 Twiss Parameter Measurement and Application to Space Charge Dynamics betatron, space-charge, emittance, lattice 3101
 
  • K. Ohmi, S. Igarashi, T. Toyama
    KEK, Ibaraki, Japan
  • H. Harada, S. Hatakeyama
    JAEA/J-PARC, Tokai-mura, Japan
  • N. Kuroo
    UTTAC, Tsukuba, Ibaraki, Japan
  • Y. Sato
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • R. Tomás, A. Wegscheider
    CERN, Geneva, Switzerland
  
  We are looking for feasible and quantitative method to evaluate space charge induced beam loss in J-PARC MR. One possible way is space charge simulation and theory based on measured Twiss parameter. Twiss parameter measurement using turn-by-turn monitors is presented. Resonance strengths of lattice magnets and space charge force are estimated by the measured Twiss parameters. Emittance growth and beam loss under the resonance strengths are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK074  
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WEPIK089 Characterization of Resonant Impedances of CERN-SPS Gate Valves impedance, simulation, coupling, vacuum 3139
 
  • T. Kaltenbacher, J. Repond, C. Vollinger
    CERN, Geneva, Switzerland
  
  For the CERN High Luminosity LHC project, a doubling of bunch intensity is foreseen. However, this intensity increase is currently limited by the LHC injector chain, in part due to longitudinal multi-bunch instabilities in the SPS. Therefore, the implementation of an accurate SPS impedance model was started some time ago in order to obtain a better understanding of instability sources and develop mitigation measures. In this paper, we present the electromagnetic characterization of commonly used all-metal gate valves with respect to their contribution to the SPS longitudinal impedance. The valve impedance was evaluated with commercially available EM-field simulation programs and verified with RF-bench measurements. Using this input, it was possible to obtain in particle simulations the dependence of the multi-bunch stability threshold on the number of these valves. A practical means of mitigation is to use a commercially available impedance shielded version of these gate valves. We also present the associated reduction in beam coupling impedance and the expected gain in beam stability if all existing unshielded valves are replaced by shielded valves.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK089  
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WEPIK090 Characterization of Shielding for the CERN-SPS Vacuum Flanges With Respect to Beam Coupling Impedance impedance, shielding, vacuum, coupling 3143
 
  • T. Kaltenbacher, C. Vollinger
    CERN, Geneva, Switzerland
  
  Longitudinal multi-bunch instabilities in the CERN-SPS pose a serious limitation for future beam intensities required for high luminosity LHC. Hence, an impedance model for the SPS accelerator was developed from which one group of vacuum flanges could be identified as being a major culprit for these instabilities. These flanges support high impedance modes and their impact on beam stability was traced to a longitudinal mode at about 1.4GHz. For improvement of multi-bunch stability threshold, this group of flanges will be shielded as part of an impedance reduction campaign. We describe the evaluation of different impedance shielding designs proposed to reduce the longitudinal beam coupling impedance of this group of vacuum flanges in the SPS. EM-field simulations were performed to identify remaining resonances in these vacuum flanges with impedance shield prototypes installed, and the simulation models were benchmarked with RF-measurements. Depending on the performance and other parameters, the most suitable shield design will be selected, built and installed. As a first step, the installation of one shielding design in some positions in the SPS is planned for the beginning of 2017.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK090  
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WEPIK091 Amplitude Dependent Closest Tune Approach Generated by Normal and Skew Octupoles octupole, coupling, simulation, injection 3147
 
  • E.H. Maclean, T. Persson, R. Tomás
    CERN, Geneva, Switzerland
  
  Amplitude dependent closest tune approach, an action dependent analogue of the DQmin generated by linear coupling, was observed in the LHC during Run1. It restricts the accessible resonance free area of the tune diagram and by altering tune spread has the potential to impact upon Landau damping. A theoretical description of such behaviour, generated by normal octupoles and linear coupling has recently been validated in the LHC, however simulation has established that amp-dependent closest approach may also be generated by a combination of normal and skew octupoles. This paper summarizes these simulation based observations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK091  
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WEPIK093 New Methods for Measurement of Nonlinear Errors in LHC Experimental IRs and Their Application in the HL-LHC dipole, dynamic-aperture, optics, collider 3155
 
  • E.H. Maclean, F.S. Carlier, J.M. Coello de Portugal, A. Garcia-Tabares, M. Giovannozzi, L. Malina, T. Persson, P.K. Skowroński, R. Tomás
    CERN, Geneva, Switzerland
  
  Studies of nonlinear errors in LHC experimental insertions (IRs) during Run 1 were based upon feed-down to tune and coupling from the crossing angle orbit bumps. Useful for validating the magnetic model, this method alone is of limited use to understand discrepancies between magnetic and beam-based measurement. Feed-down from high-order multipoles is also difficult to observe. During Run 2 several alternative methods were tested in the LHC. This paper summarizes the results of these tests, and comments on their potential application to the High-Luminosity LHC upgrade.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK093  
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WEPIK098 Resonant Kicker System With Sub-part-per-million Amplitude Stability kicker, electron, operation, dipole 3174
 
  • M. Paraliev, C.H. Gough
    PSI, Villigen PSI, Switzerland
  
  High stability resonant kicker magnet systems have been developed as part of the fast electron beam switching system of Swiss Free Electron Laser (SwissFEL). They are designed to separate two closely spaced electron bunches (28 ns apart) accelerated in one RF macro-pulse and to send them to two separate undulator lines. High shot-to-shot amplitude stability is required to minimize the disturbance of the electron beam trajectories and to ensure stable X-ray lasing. The stability and speed was unlikely to be achieved by standard pulsed systems and a novel 18 MHz, lumped-element resonator deflector with high Q was developed. It is driven into resonance by a specialized pulsed RF driver. At resonance, the circulating currents can approach 300 A and the resulting magnetic field gives the required deflection to the electron bunches. The advanced DC offset measurement system is also described in this paper. The measured stability reached less than 1 ppm (10e-6) rms, well within the project requirements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK098  
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WEPIK102 Measurement of RF Resonances and Measured Impact on Transverse Multibunch Instabilities from In-vacuum Insertions Devices vacuum, damping, coupling, dipole 3188
 
  • G. Rehm
    DLS, Oxfordshire, United Kingdom
  
  Diamond Light Source has currently 15 in-vacuum insertion devices (ID) installed, mostly built in-house. Their measured impact on multi-bunch mode damping as a result of varying magnet gap was shown before, now we augment these with measurements of broadband frequency spectra with stored beam obtained using an antenna placed in the ID vacuum. Finally, we present off-line measurements of resonances in the ID vessel acquired using a vector network analyser and two antennae installed in-vacuum.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK102  
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WEPIK111 Derivation of a Finite Element Formulation From a Lagrangian for the Electromagnetic Potentials electromagnetic-fields, coupling, operation, interface 3208
 
  • A.R. Vrielink, M.H. Nasr, S.G. Tantawi
    SLAC, Menlo Park, California, USA
  
  Conventional electromagnetic finite element solvers typically solve a weak formulation of the Helmholtz wave equation. While mathematically this approach is correct, it does not fully reflect the fundamental physics involved. We offer an alternative variational formulation which is not derived from the Helmholtz wave equation but is more fundamentally tied to the physics of the system: a Lagrangian for the electromagnetic potentials. Solving for the potentials directly allows for a natural accounting of the beam wave interaction. It could also potentially avoid the issue of deleterious spurious modes inherent when selecting the Coulomb gauge and enforcing the subsequent divergence free condition, eliminating the need for vector basis functions. Herein we present the theory and the resulting formulation including a discussion on gauge fixing. We conclude with some numerical results demonstrating the potential of this formulation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK111  
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WEPIK116 Aberration Compensation in a Skew Parametric-Resonance Ionization Cooling Channel multipole, damping, simulation, sextupole 3221
 
  • A.V. Sy, Y.S. Derbenev, V.S. Morozov
    JLab, Newport News, Virginia, USA
  • A. Afanasev
    GWU, Washington, USA
  • Y. Bao
    UCR, Riverside, California, USA
  • R.P. Johnson
    Muons, Inc, Illinois, USA
  
  Funding: This work was supported in part by U.S. DOE STTR Grant DE-SC0005589. Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Skew Parametric-resonance Ionization Cooling (Skew PIC) represents a novel method for focusing of highly divergent particle beams, as in the final 6D cooling stage of a high-luminosity muon collider. In the muon collider concept, the resultant equilibrium transverse emittances from cooling with Skew PIC are an order of magnitude smaller than in conventional ionization cooling. The concept makes use of coupling of the transverse dynamic behavior, and the linear dynamics are well-behaved with good agreement between analytic solutions and simulation results. Compared to the uncoupled system, coupling of the transverse dynamic behavior purports to reduce the number of multipoles required for aberration compensation while also avoiding unwanted resonances. Aberration compensation is more complicated in the coupled case, especially in the high-luminosity muon collider application where equilibrium angular spreads in the cooling channel are on the order of 200 mrad. We present recent progress on aberration compensation for control of highly divergent muon beams in the coupled correlated optics channel, and a simple cooling model to test the transverse acceptance of the channel. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK116  
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WEPIK118 Synchronous Phase Shift from Beam Loading Analysis beam-loading, cavity, storage-ring, operation 3227
 
  • G. Bassi, A. Blednykh, J. Rose, V.V. Smaluk, J. Tagger
    BNL, Upton, Long Island, New York, USA
  
  We discuss measurements, performed in the NSLS-II storage ring, of the synchronous phase shift as a function of single bunch current from beam loading parameters. The synchronous phase is calculated from the forward and reflected power measured in the RF cavities. The comparison with direct synchronous phase measurements shows good agreement.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK118  
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WEPIK122 Applying Square Matrix to Optimize Storage Ring Nonlinear Lattice lattice, dynamic-aperture, sextupole, storage-ring 3241
 
  • Y. Li, L. Yu
    BNL, Upton, Long Island, New York, USA
  
  Funding: Supported by US DOE Contract No. DE-AC02-98CH10886 and DE-SC0012704.
A new method of using linear algebra technique to analyze periodical nonlinear beam dynamics is presented. For a given dynamical system, a square upper triangular transfer matrix is constructed out of a one turn Taylor transfer map. First we separate the matrix into different low dimensional invariant subspaces according to their eigenvalues. Then a stable Jordan transformation can be obtained on each subspace. The transformation provides an excellent action-angle approximation to the solution of the nonlinear dynamics. And the deviation of the new action from constancy provides a measure of the nonlinearity of the motions, which provides a novel method to optimize the nonlinear dynamic system. We applied this method to optimize various rings, such as NSLS-II, SPEAR3, and APS-U lattice, the promising dynamic aperture have been achieved from both tracking simulation and experimental measurements. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK122  
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WEPVA097 Upgrading the SPS Fast Extraction Kicker Systems for HL-LHC kicker, impedance, electron, extraction 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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WEPVA141 Ion Cyclotron Resonance Heating Transmitter Opening Switch Upgrade operation, plasma, high-voltage, impedance 3600
 
  • M.P.J. Gaudreau, M.K. Kempkes, 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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THXA1 Beam-Based Optimization of Storage Ring Nonlinear Beam Dynamics sextupole, dynamic-aperture, injection, storage-ring 3627
 
  • X. Huang, J.A. Safranek
    SLAC, Menlo Park, California, USA
  
  Funding: Work supported in part by the U.S. Department of Energy under contract number DE-AC02-76SF00515.
This paper will present considerations and algorithms for direct online optimization of the nonlinear beam dynamics of existing and future storage rings. The experimental setup and results from using this approach to improve the dynamic aperture of the SPEAR3 storage ring, using the robust conjugate direction search method and the particle swarm optimization method, will be covered. 		 
slides icon Slides THXA1 [1.589 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THXA1  
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THPAB049 Progress in the Understanding of the Performance Limitations in the CERN Low Energy Ion Ring ion, sextupole, optics, space-charge 3819
 
  • A. Huschauer, H. Bartosik, S. Hancock, V. Kain
    CERN, Geneva, Switzerland
  
  The performance of heavy ion beams in the CERN Low Energy Ion Ring is mainly limited by beam loss occuring during the radio-frequency capture and the first part of acceleration. Since October 2015, the driving mechanism of these losses has been studied in detail and an interplay of direct space charge forces and excited betatron resonances was identified as the most plausible explanation of the phenomenon. In this paper we summarize the current understanding of the loss mechanism by presenting recent experimental and simulation studies. We discuss strategies to mitigate beam loss and further improve the performance of the accelerator in the future.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB049  
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THPAB081 The Effects of Space-Charge on the Dynamics of the Ion Booster in the Jefferson Lab EIC (JLEIC) booster, space-charge, injection, emittance 3906
 
  • E.W. Nissen, S.A. Bogacz
    JLab, Newport News, Virginia, USA
  
  Funding: Notice: This manuscript has been authored by Jefferson Science Associates, LLC under Contract No. DE-AC05-06OR23177 with the U.S. Department of Energy.
Optimization of the booster synchrotron design to operate in the extreme space-charge dominated regime is proposed. This study is motivated by the ultra-high luminosity promised by the JLEIC accelerator complex, which poses several beam dynamics and lattice design challenges for its individual components. We examine the effects of space charge on the dynamics of the booster synchrotron for the proposed JLEIC electron ion collider. This booster will inject and accumulate protons and heavy ions at an energy of 280 MeV and then engage in a process of acceleration and electron cooling to bring it to its extraction energy of 8 GeV. This would then be sent into the ion collider ring part of JLEIC. In order to examine the effects of space charge on the dynamics of this process we use the software SYNERGIA. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB081  
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THPAB100 On the Impact of Empty Buckets on the Ferrite Cavity Control Loop Dynamics in High Intensity Hadron Synchrotrons controls, cavity, beam-loading, simulation 3954
 
  • D. Mihailescu Stoica, D. Domont-Yankulova
    Technische Universität Darmstadt (TU Darmstadt, RMR), Darmstadt, Germany
  • D. Domont-Yankulova, H. Klingbeil
    TEMF, TU Darmstadt, Darmstadt, Germany
  • H. Klingbeil, D.E.M. Lens
    GSI, Darmstadt, Germany
  
  Funding: Supported by the Helmholtz Graduate School for Hadron and Ion Research
Due to technical reasons two of ten buckets have to stay empty in the planned SIS100 synchrotron at the GSI Helmholtzzentrum für Schwerionenforschung. The planned low level RF control systems consist of linear P and PI type controllers. These are responsible to maintain a desired phase and amplitude of the gap voltage. In addition the cavity is controlled to follow a prescribed resonance frequency ramp. In SIS100 the acceleration will be performed by ferrite cavities with comparatively small quality factors. Therefore, effects resulting from transient beam loading have to be expected. Influences due to empty buckets are analysed in the frequency domain and particle tracking simulations are carried out to estimate the effect on the overall system with particular consideration of emittance growth and particle loss. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB100  
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THPAB129 Contribution to the ESS LLRF System by Polish Electronic Group LLRF, controls, cavity, FPGA 4026
 
  • J. Szewiński, M. Gosk, Z. Gołębiewski, P. Krawczyk, I.M. Kudla
    NCBJ, Świerk/Otwock, Poland
  • A. Abramowicz, K. Czuba, M.G. Grzegrzolka, I. Rutkowski
    Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
  • W. Cichalewski, D.R. Makowski, A. Napieralski
    TUL-DMCS, Łódź, Poland
  
  Funding: Described work will be done as a part of polish in-kind contribution, granted by the Polish Ministry of Science and Higher Education in the decision number DIR/WK/2016/03.
Development of the LLRF system at ESS is coordinated by the Lund University, but part of it, LLRF systems for M-Beta and H-Beta sections, will be delivered within in-kind contribution from Poland. This document will describe the scope of work, work plan, and technical details of the selected components of the M-Beta and H-Beta LLRF systems sections. Described contribution will be made by the Polish Electronic Group (PEG), a consortium of three scientific units. LLRF system for ESS will be made of both, commercially available components and components designed specially for this project, and those last ones will be presented and described here. Except the technical details, the organizational aspects, such as schedule, project management or quality control, will be presented as well. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB129  
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THPIK021 Structural Mechanical Analysis of 4-Rod RFQ Structures in View of a Newly Revised CW RFQ for the HLI at GSI rfq, quadrupole, linac, simulation 4142
 
  • D. Koser, H. Podlech
    IAP, Frankfurt am Main, Germany
  • P. Gerhard, L. Groening
    GSI, Darmstadt, Germany
  • O.K. Kester
    TRIUMF, Vancouver, Canada
  
  Funding: BMBF Contr. No. 05P15RFRBA
The High Charge State Injector (HLI) at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany, serves as one of the two injector linacs for the UNILAC as well as dedicated injector for the upcoming cw linac project for super heavy element research. As the front end of the HLI is planned to be upgraded for cw operation a newly revised cw capable RFQ structure with an operating frequency of 108 MHz is required. The existent 4-rod structure, which was commissioned at the HLI in 2010, suffers from severe modulated rf power reflections originating from mechanical oscillations of the electrodes that both limit the achievable performance and impede stable operation*. Besides preceding vibration measurements that were done by GSI using a laser vibrometer**, the structural mechanical behavior of the 4-rod geometry was extensively analyzed using ANSYS Workbench. Thereby the crucial mechanical eigenmodes could be identified and their impact on the rf properties was investigated by simulations using CST MWS. A completely newly revised 4-rod RFQ design with optimized structural rigidity was developed of which a 6-stem prototype is currently being manufactured.
*P. Gerhard et al., Experience With a 4-Rod CW Radio Frequency Quadrupole, LINAC12, THPLB07
**P. Gerhard et al., In Situ Measurements of Mechanical Vibrations of a 4-Rod RFQ at GSI, LINAC14, TUPP057 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK021  
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THPIK113 Tuner of a Second Harmonic Cavity of the Fermilab Booster cavity, injection, booster, extraction 4362
 
  • I. Terechkine, K.L. Duel, R.L. Madrak, A.V. Makarov, G.V. Romanov, D. Sun, C.-Y. Tan
    Fermilab, Batavia, Illinois, USA
  
  Introducing a second harmonic cavity in the accelerating system of the Fermilab Booster promises significant reduction of the particle beam loss during the injection, transition, and extraction stages. To follow the changing energy of the beam during acceleration cycles, the cavity is equipped with a tuner that employs perpendicularly biased AL800 garnet material as the frequency tuning media. The required tuning range of the cavity is from 75.73 MHz at injection to 105.64 MHz at extraction. This large range necessitates the use of a relatively low bias magnetic field at injection, which could lead to high RF loss power density in the garnet, or a strong bias magnetic field at extraction, which could result in high power consumption in the tuner's bias magnet. The required 15 Hz repetition rate of the device and high sensitivity of the local RF power loss to the level of the magnetic field added to the challenges of the bias system design. In this report, the main features of a proposed prototype of the second harmonic cavity tuner are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK113  
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THPIK120 The RF and Mechanical Design of a Compact, 2.5 kW, 1.3 GHz Resonant Loop Coupler for the APEX Buncher Cavity cavity, vacuum, electron, operation 4380
 
  • S.P. Virostek, F. Sannibale, J.W. Staples
    LBNL, Berkeley, California, USA
  • H.J. Qian
    DESY Zeuthen, Zeuthen, Germany
  
  Funding: This work is supported by the Office of Science, United States Department of Energy under DOE contract DE-AC02-05CH11231.
The Advanced Photo-injector Experiment (APEX) at the Lawrence Berkeley National Laboratory (LBNL) is an injector system designed to demonstrate the capability of a normal conducting 186 MHz RF gun operating in CW mode to deliver the brightness required by X-ray FEL applications operating at MHz repetition rate, such as LCLS-II. A 240 kV, 1.3 GHz CW buncher cavity design was developed as part of the APEX experiment. The two-cell cavity profile has been optimized to minimize the RF power requirements and to remove multipacting resonances over the full range of operation. In order to excite the cavity stably at pi-mode and remove the dipole-like coupler kick, the two cells are to be independently driven by four, 2.5 kW, coaxial resonant loop couplers with integrated ceramic windows and a matching section in the body of the coupler. The coupler's inner conductor has a single diameter change at a specified distance from the ceramic insulator in order to cancel the wave reflected from the ceramic window, thus comprising the matching section. The details of the RF analysis, mechanical design, fabrication and testing of the coupler are presented here. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK120  
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THPVA004 Pushing the Space Charge Limit: Electron Lenses in High-Intensity Synchrotrons? space-charge, electron, synchrotron, ion 4417
 
  • W.D. Stem, O. Boine-Frankenheim
    TEMF, TU Darmstadt, Darmstadt, Germany
  • O. Boine-Frankenheim
    GSI, Darmstadt, Germany
  
  Funding: Work is supported by BMBF contract FKZ:05P15RDRBA
Several accelerator projects require an increase in the number of particles per bunch, which is constrained by the space charge limit. Above this limit the transverse space charge force in combination with the lattice structure causes beam quality degradation and beam loss. Proposed devices to mitigate this beam loss in ion beams are electron lenses. An electron lens imparts a nonlinear, localized focusing kick to counteract the (global) space-charge forces in the primary beam. This effort is met with many challenges, including a reduced dynamic aperture (DA), resonance crossing, and beam-beam alignment. This contribution provides a detailed study of idealized electron lens use in high-intensity particle accelerators, including a comparison between analytical calculations and pyORBIT particle-in-cell (PIC) simulations. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA004  
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THPVA017 Integer Spin Resonance Crossing With Preserving Beam Polarization on VEPP-4M polarization, acceleration, solenoid, experiment 4451
 
  • A.K. Barladyan, A.Yu. Barnyakov, S.A. Glukhov, S.E. Karnaev, E.B. Levichev, S.A. Nikitin, I.B. Nikolaev, I.N. Okunev, P.A. Piminov, A.G. Shamov, A.N. Zhuravlev
    BINP SB RAS, Novosibirsk, Russia
  
  The method to preserve the electron beam polarization on the VEPP-4M storage ring during acceleration with crossing the integer spin resonance energy E=1763 MeV is described. It is based on the use of the non-compensated longitudinal magnetic field of the KEDR detector. This method has been successfully applied for the needs of the R measurement experiment.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA017  
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THPVA032 Space-Charge Simulation of Integrable Rapid Cycling Synchrotron lattice, sextupole, space-charge, optics 4501
 
  • J.S. Eldred, A. Valishev
    Fermilab, Batavia, Illinois, USA
  
  Integrable optics is an innovation in particle accelerator design that enables strong nonlinear focusing without generating parametric resonances. We use a Synergia space-charge simulation to investigate the application of integrable optics to a high-intensity hadron ring that could replace the Fermilab Booster. We find that incorporating integrability into the design suppresses the beam halo generated by a mismatched KV beam. Our integrable rapid cycling synchrotron (iRCS) design includes other features of modern ring design such as low momentum compaction factor and harmonically canceling sextupoles. Experimental tests of high-intensity beams in integrable lattices will take place over the next several years at the Fermilab Integrable Optics Test Accelerator (IOTA) and the University of Maryland Electron Ring (UMER).  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA032  
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THPVA056 Study of Influence of Dipole and Quadrupole Power Ripple on Slow Extraction for XiPAF extraction, simulation, quadrupole, dipole 4569
 
  • Q. Zhang, G.R. Li, Z.Y. Lin, X.W. Wang, H.J. Yao, S.X. Zheng
    TUB, Beijing, People's Republic of China
  • X. Guan
    Tsinghua University, Beijing, People's Republic of China
  
  The 3rd resonant slow extraction and RF-Knockout technology has been adopted for XiPAF, which was designed for proton therapy and single event effects. The separatrix of stable region will fluctuate in the process of slow extraction due to power ripple, hence influence the uniform of extracted beam and the extraction efficiency. The influence of dipole and quadrupole power ripple is studied in theory and simulated by a MPI parallel multi-particle program, a method of making beam less sensitive to power ripple is discussed and verified by simulation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA056  
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THPVA133 HEATHER - HElium Ion Accelerator for RadioTHERapy ion, acceleration, proton, injection 4768
 
  • J. Taylor, T.R. Edgecock
    University of Huddersfield, Huddersfield, United Kingdom
  • S. Green
    University Birmingham, Birmingham, United Kingdom
  • C. Johnstone
    Fermilab, Batavia, Illinois, USA
  
  A non-scaling fixed field alternating gradient (nsFFAG) accelerator is being designed for helium ion therapy. This facility will consist of 2 superconducting rings, treating with helium ions (He2+ ) and image with hydrogen ions (H + 2 ). Currently only carbon ions are used to treat cancer, yet there is an increasing interest in the use of lighter ions for therapy. Lighter ions have reduced dose tail beyond the tumour compared to carbon, caused by low Z secondary particles produced via inelastic nuclear reactions. An FFAG approach for helium therapy has never been previously considered. Having demonstrated isochronous acceleration from 0.5 MeV to 900 MeV, we now demonstrate the survival of a realistic beam across both stages.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA133  
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