Keyword: space-charge
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MOPME005 Simulation of the Extraction and Transport of a Beam from the SILHI Source with the Warp Code ion, plasma, extraction, simulation 385
 
  • A. Chancé, N. Chauvin
    CEA/DSM/IRFU, France
  
  In a low energy beam transfer (LEBT) line, space charge effects are dominant and make the motion of the particles strongly non-linear. So, the beam dynamics is directly dependent on the 6D distribution of the particles after the ion source extraction system. It is thus essential to simulate accurately the source extraction region and the space charge compensation after it to try to reach an agreement between the simulations and the measurements. Generally, the ion source extraction system is simulated with electrostatic codes (often using simple model for space charge) from which the 6D beam distribution is derived. Then, this distribution can be used as an initial condition to simulate the beam transport in the LEBT with a time dependent PIC code that takes into account space charge compensation. We propose here to simulate accurately the SILHI source extraction system with the Warp and AXCEL-INP codes. The SILHI ion source will be quickly presented and some simulations results will be given and discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPME005  
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MOPME013 A Python Poisson Solver for 3D Space Charge Computations in Structures with Arbitrary Shaped Boundaries simulation, rfq, electron, ion 406
 
  • G. Pöplau, C. Potratz
    COMPAEC e.G., Rostock, Germany
  
  Numerical techniques in the field of particle accelerators are mainly driven by the design of next-generation accelerators: The need for higher simulation complexity and the necessity for more and more specialized algorithms arises from the ever increasing need to include a broader range of physical effects and geometrical details in a computer simulation. This, on the other hand requires fast and reliable simulation tools for a limited user base. Therefore, new approaches in simulation software development are necessary to provide useful tools that are well-suited for the task at hand and that can be easily maintained and adapted by a small user community. We show how Python can be used to solve numerical problems arising from particle accelerator design efficiently. As model problem, the computation of space charge effects of a bunch in RFQs including the vane geometry was chosen and a suited solver was implemented in Python.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPME013  
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MOPME019 Study of a Fast Convolution Method for Solving the Space Charge Fields of Charged Particle Bunches simulation, electron, ion, electromagnetic-fields 418
 
  • D. Zheng, A. Markoviḱ, G. Pöplau, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  
  The kernel of beam dynamics simulations using the particle-in-cell (PIC) model is the solution of Poisson's equation for the electric potential. A very common way to solve Poisson's equation is to use the convolution of charge density and Green's function, the so-called Green's function method. Additionally, the integrated Green's function method* is being used in order to achieve a higher accuracy. For both methods, the convolutions are done using fast Fourier transform based on the convolution theorem. However, the construction of the integrated Green's function and the further convolution is still very time-consuming. The computation can be accelerated without loosing precision if the calculation of Green’s function values is limited to that part of the computational domain with non-zero grid charge density. In this paper we present a general numerical study of these Green's function methods for computing the potential of different bunches: The results can also be used in other simulation codes to improve efficiency.
* J. Qiang, S. Lidia, R. D. Ryne, and C. Limborg-Deprey, “A Three-Dimensional Quasi-Static Model for High Brightness Beam Dynamics simulation,” Phys. Rev. ST Accel. Beams, vol 9, 044204 (2006). 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPME019  
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MOPME038 Space Charge Simulation in COSY using The Fast Multipole Method emittance, multipole, simulation, collider 460
 
  • B.T. Loseth, M. Berz, K. Makino
    MSU, East Lansing, Michigan, USA
  • P. Snopok
    Fermilab, Batavia, Illinois, USA
  • H. Zhang
    JLab, Newport News, Virginia, USA
  
  A method is implemented in COSY Infinity that allows the computation of space charge effects of arbitrary and large distributions of particles in an efficient and accurate way based on a variant of the Fast Multipole Method (FMM). It relies on an automatic multigrid-based decomposition of charges in near and far regions and the use of high-order differential algebra methods to obtain decompositions of far fields that lead to an error that scales with a high power of the order. Given an ensemble of N particles, the method allows the computation of the self-fields of all particles on each other with a computational expense that scales as O(N). Furthermore, the method allows the computation of all high-order multipoles of the space charge fields that are necessary for the computation of high-order transfer maps and all resulting aberrations. Space charge effects are crucial in modeling the latter stages of the six-dimensional (6D) cooling channel for the Muon Collider. Results of simulating the 6D cooling channel for the Muon Collider using the FMM method and other tools and improvements implemented for ionization cooling lattices are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPME038  
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MOPRI001 Induced Heating Power Evaluation in RIB Transfer Line of SPIRAL2 ion, beam-losses, solenoid, ECR 570
 
  • N.Yu. Kazarinov
    JINR, Dubna, Moscow Region, Russia
  • D. Boutin, F.R. Osswald
    IPHC, Strasbourg Cedex 2, France
  
  Radioactive Ion Beams of SPIRAL2 project will be produced in the ECR ion source using the Helium as supporting gas. RIB transported in the transfer lines have a multi-component structure and total current of the beams is defined by Helium ions. The total power of Helium component may reach 300 W. The focusing force acting on the ions in the transfer beam line is strongly dependent on mass-to-charge ratio (this is valid for magnetic optical elements). For this reason supporting gas ions will be lost at initial part of the beam line between ECR ion source and analyzing magnet. The Helium beam losses and induced heating power density at the wall of vacuum tube in RIB transfer line of SPIRAL2 during transportation of Ar, Xe and U ion beam are evaluated in this report.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI001  
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MOPRI010 Laser Ablation Ion Source for the KEK Digital Accelerator ion, laser, extraction, simulation 598
 
  • N. Munemoto
    Department of Energy Sciences, Tokyo Institute of Technology, Yokohama, Japan
  • Y. Fuwa, S. Ikeda, M. Kumaki
    RIKEN, Saitama, Japan
  • Y. Fuwa
    Kyoto ICR, Uji, Kyoto, Japan
  • S. Ikeda, K. Takayama
    TIT, Yokohama, Japan
  • M. Kumaki
    RISE, Tokyo, Japan
  • M. Okamura
    BNL, Upton, Long Island, New York, USA
  • S. Takano, K. Takayama
    KEK, Ibaraki, Japan
  • K. Takayama
    Sokendai, Ibaraki, Japan
  
  KEK Digital Accelerator (DA) is a small scale induction synchrotron and operated at 10Hz and recently has succeeded to accelerate gaseous ions*. There is a strong demand of fully striped carbon ions because the DA is regarded as the second generation of cancer therapy driver, which does not require an injector and electron stripper. We need a novel carbon ion source providing C6+ beams, which are directly injected into the DA and accelerated up to required energy. For this purpose, a laser ablation ion source(LAIS) is promising**. To obtain high yield C6+ ions from ablation plasma, the laser irradiation condition has been evaluated and relationship between beam properties of charge spectrum, intensity, and temperature, and carbon target materials were examined. Two laser systems, long pulse (6 ns) and short pulse (170 ps), were employed to irradiate a graphite and amorphous carbon target. The current densities and profile of the generated plasmas in time were measured and charge state distributions were analyzed. In addition we will report a full design integrating this LAIS, the extraction system, the longitudinal chopper system, and the low energy beam transport line.
* T.Yoshimoto et al., presented in this conference
** N.Munemoto et al., Proceedings of ICIS2013, published in Rev. Sci. Inst. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI010  
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MOPRI026 Complete Simulation of Laser Induced Field Emission from Nanostructures Using a DGTD, PIC and FEM Code electron, laser, simulation, cathode 645
 
  • A. Fallahi, F.X. Kärtner
    CFEL, Hamburg, Germany
  • K.K. Berggren, R. Hobbs, F.X. Kärtner, P.D. Keathley, M.E. Swanwick, L.F. Velasquez-Garcia, Y. Yang
    MIT, Cambridge, Massachusetts, USA
  
  Funding: DARPA contract number N66001-11-1-4192 and the Center for Free-Electron Laser Science, DESY Hamburg.
We present a general and efficient numerical algorithm for studying laser induced field emission from nanostructures. The method combines the Discontinuous Galerkin Time Domain (DGTD) method for solving the optical field profile, the Particle-In-Cell (PIC) method for capturing the electron dynamics and the Finite Element Method (FEM) for solving the static field distribution. The charge distribution is introduced to the time-domain method based on a modified Fowler-Nordheim field emission model, which accounts for the band-bending of the charge carriers at the emitter surface. This algorithm is capable of considering various effects in the emission process such as space-charge, Coulomb blockade and image charge. Simulation results are compared with experimental findings for optically driven electron emission from nanosharp Si-tips. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI026  
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MOPRI049 An Ultracold Electron Facility in Manchester electron, laser, emittance, extraction 714
 
  • Ö. Mete, R. Appleby, W. Bertsche, M.A. Harvey, G.X. Xia
    UMAN, Manchester, United Kingdom
  • S. Chattopadhyay
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • A.J. Murray
    The University of Manchester, The Photon Science Institute, Manchester, United Kingdom
  
  An ultra-cold atom based electron source (UCAE) facility has been built in the Photon Science Institute (PSI), University of Manchester. In this paper, the key components and working principles of this source are introduced. Pre-commissioning status of this facility and the preliminary simulations results are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI049  
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MOPRI088 Beam Transport Experiments Using Gabor Lenses electron, beam-transport, experiment, focusing 818
 
  • K. Schulte, M. Droba, S. Klaproth, O. Meusel, D. Noll, U. Ratzinger
    IAP, Frankfurt am Main, Germany
  
  A prototype Gabor lens has successfully been tested at the GSI High Current Test Injector (HOSTI)*. The experiments comprised the investigation of an emittance dominated and a space-charge dominated beam transport. In particular, the high-current measurements represent a necessary step towards evaluating the focusing performance of the lens and to gain experience in a real accelerator environment. Besides the evaluation of the technical feasibility, the behavior of the electron cloud was characterized by the parameter analysis of the confined non-neutral plasma during beam transport measurements as well as subsequently performed diagnostic experiments. This contribution will present experimental results as well as numerical studies on an improved Gabor lens design for the possible application at the GSI High Current Injector (HSI) in the context of an upgrade program for FAIR**.
*K. Schulte et al., Proc. of IPAC'13, Shanghai, China, 2013, THPWO021
**L. Dahl, Proc. of HIAT’09, Venice, Italy, 2009, FR-01
 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI088  
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TUOAB03 Nonlinear Optics for Suppression of Halo Formation in Space Charge Dominated Beams focusing, quadrupole, emittance, simulation 953
 
  • Y.K. Batygin, A. Scheinker
    LANL, Los Alamos, New Mexico, USA
  • C. Li
    IMP, Lanzhou, People's Republic of China
  
  Traditional accelerator designs utilize linear focusing elements (quadrupoles, solenoids) to provide stable particle motion. High – intensity rms - matched non - uniform beams are intrinsically mismatched with linear focusing structure. It results in space charge induced beam emittance growth and halo formation, which can be suppressed in a quadrupole channel with higher-order multipole field components. In this paper, overview of FODO quadrupole channels with arbitrary multipoles is given. Effective averaged potential is presented for the structure with periodic combination of multipole lenses and quadrupoles. Density of matched beam avoiding emittance growth and halo formation is derived. Performed analysis allows matching of realistic beam with the internal structure of the focusing field. Beam dynamics studies with suppressed halo are presented and discussed.  
slides icon Slides TUOAB03 [3.404 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUOAB03  
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TUPRO061 Benchmarking Beam Envelope Models for the European Spallation Source DTL, simulation, dipole, linac 1174
 
  • I. List
    Cosylab, Ljubljana, Slovenia
  • E. Laface
    ESS, Lund, Sweden
  
  TraceWin is used at the European Spallation Source (ESS) as the design tool, while fast and accurate on-line models will be needed during the operations. Three models are compared: the ESS Linac Simulator (ELS), TraceWin and the OpenXAL. In all of the benchmarked models, dynamics of each beam-line element is, to the first order, represented by a transfer matrix. Differences in the matrices occur, since different reference frames are used and as well different assumptions about the energy of the particles are made. General transformations of the reference frames will be presented. Using those, the comparison of transfer maps among TraceWin and OpenXAL are given. When the differences between TraceWin and OpenXAL were unclear, the benchmark versus other code, like MAD-X and Dynac was done. The best implementations were combined into a new on-line model implementation Java ELS (or JELS) and at last the comparison of the latter with TraceWin is given.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO061  
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TUPME043 Temporal Electron-bunch Shaping from a Photoinjector for Advanced Accelerator Applications laser, wakefield, acceleration, gun 1454
 
  • F. Lemery, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • P. Piot
    Fermilab, Batavia, Illinois, USA
  
  Advanced-accelerator applications often require the production of bunches with shaped temporal distributions. An example of sought-after shape is a linearly-ramped current profile that can be improve the transformer ratio in beam-driven acceleration, or produce energy-modulated pulse for, e.g., the subsequent generation of THz radiation. Typically,  such a shaping is achieved by manipulating ultra-relativistic electron bunches. In this contribution we discuss the possibility of shaping the bunch via photoemission and demonstrate using particle-in-cell simulations the production of MeV electron bunches with quasi-ramped current profile.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME043  
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TUPME059 Longitudinal Bunch Shaping with a Double Dogleg based Emittance Exchange Beam Line emittance, controls, experiment, cavity 1506
 
  • G. Ha, M.E. Conde, W. Gai, C.-J. Jing, K.-J. Kim, J.G. Power, A. Zholents
    ANL, Argonne, Illinois, USA
  • M.-H. Cho, G. Ha, W. Namkung
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  • C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
  
  Funding: Work supported by High Energy Physics, Office of Science, US DOE.
A new program is under development at Argonne National Laboratory (ANL) to use an emittance exchange (EEX) beamline to produce longitudinally shaped electron bunches. While the ultimate goal is to generate triangular shapes for high transformer ratio wakefield acceleration we are also exploring, in general, the capability of the double dogleg EEX beamline to control the bunch shape. We are studying effects that degrade the quality of the longitudinal current profile including: non-uniform particle distribution, emittance, the deflecting cavity thick-lens effect, 2nd order effects, space charge effects and coherent synchrotron radiation effects. We will present the double dogleg EEX beamline layout and the diagnostic design as well as give a progress report on the experimental status of the program. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME059  
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TUPRI017 Artificial Collisions, Entropy and Emittance Growth in Computer Simulations of Intense Beams emittance, simulation, focusing, scattering 1588
 
  • O. Boine-Frankenheim, I. Hofmann, J. Struckmeier
    GSI, Darmstadt, Germany
  
  During particle tracking with self-consistent space charge artificial collision between the macro-particles lead to diffusion-like, numerical effects. The artificial collisions generate a stochastic noise spectrum. As a consequence the entropy and the emittance of the particle beam can growth along periodic focusing structures. The growth rates depend on the number of simulation macro-particles and on the space charge tune shifts. For long-term tracking studies the numerical diffusion can lead to incorrect beam loss predictions. In our study we present analytical prediction for the numerical friction and diffusion in 2D and 3D simulations. For simple focusing structures with derive a relation between the friction coefficient and the entropy growth. The scaling of the friction coefficient with the macro-particle number and the space charge tune shift is obtained from 2D and 3D simulations and compared to the analytic predictions.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI017  
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TUPRI018 Transition Energy Crossing in the Future FAIR SIS-100 for Proton Operation proton, quadrupole, synchrotron, feedback 1591
 
  • S. Aumon, D. Ondreka, S. Sorge
    GSI, Darmstadt, Germany
  • K. Groß
    TEMF, TU Darmstadt, Darmstadt, Germany
  
  The FAIR project foresees to deliver an intense single bunch beam with 2·1013 protons of 50ns duration to the experiments. Besides the original γt-shift scenario, an alternative RF proton cycle has been recently studied: the transition energy is crossed with possibly a gamma transition jump. The flexibility of the lattice allowing to change the value of γt, a transition crossing has been considered for two possible energies. This challenging scenario is limited by several constraints such as space charge, a small momentum acceptance and by the required RF manipulations aiming to produce the final single bunch beam in the future SIS-100. This paper focuses on how the high intensity beam would suffer of the mismatch in bunch length at transition and new sets of beam parameter are defined for the proton beam. The jump quadrupole system is also presented. The applicability of the foreseen longitudinal feedback system to cure quadrupolar oscillations is also discussed in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI018  
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TUPRI019 Incoherent and Coherent Effects of Space Charge Limited Electron Clouds electron, wakefield, simulation, dipole 1594
 
  • F.B. Petrov, O. Boine-Frankenheim, O.S. Haas
    TEMF, TU Darmstadt, Darmstadt, Germany
  
  Funding: Work is supported by the BMBF under contract 05H12RD7.
Recent studies show that the space charge limited (saturated) electron cloud generated by relativistic bunches has strongly inhomogeneous distribution. In particular, a dense electron sheath is formed near the pipe wall. This feature modifies the stopping powers and the microwave transmission compared with the uniform cloud case. In this paper we investigate further the influence of the space charge limited electron cloud on relativistic bunches. In particular, we focus on the incoherent tune spread and compare the results with the homogeneous cloud case. We derive analytical expressions governing the pinch dynamics of the saturated cloud in round geometry. The contribution of the electron cloud sheath to the wake fields is investigated as well. Findings of the analytical theory are then successfully compared with numerical particle-in-cell simulations. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI019  
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TUPRI024 Simulation of Space Charge Dynamics on HPC simulation, GPU, distributed, controls 1609
 
  • N.V. Kulabukhova, S.N. Andrianov
    St. Petersburg State University, St. Petersburg, Russia
  • A. Bogdanov, A. Degtyarev
    Saint Petersburg State University, Saint Petersburg, Russia
  
  To represent the space charge forces of beam a software based on analytical models for space charge distributions was developed. Special algorithm for predictor-corrector method for beam map evaluation scheme including the space charge forces were used. This method allows us to evaluate the map along the reference trajectory and to analyze beam envelope dynamics. In three dimensional models the number of computing resources we use is significant. For this purpose graphical processors are used. This software is a part of Virtual Accelerator concept which is considered as a set of services and tools of modeling beam dynamics in accelerators on distributed computing resources.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI024  
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TUPRI027 Detailed Magnetic Model Simulations of the H− Injection Chicane Magnets for the CERN PS Booster Upgrade, including Eddy Currents, and Influence on Beam Dynamics injection, simulation, vacuum, emittance 1618
 
  • E. Benedetto, B. Balhan, J. Borburgh, C. Carli, V. Forte, M. Martini
    CERN, Geneva, Switzerland
  • V. Forte
    Université Blaise Pascal, Clermont-Ferrand, France
  
  The CERN PS Booster will be upgraded with an H− injection system. The chicane magnets for the injection bump ramp-down in 5 ms and generate eddy currents in the inconel vacuum chamber which perturb the homogeneity of the magnetic field. The multipolar field components are extracted from 3D OPERA simulations and are included in the lattice model. The beta-beating correction is computed all along the ramp and complete tracking simulations including space-charge are performed to evaluate the impact of these perturbations and their correction.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI027  
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TUPRI029 The CERN PS Booster Space Charge Simulations with a Realistic Model for Alignment and Field Errors simulation, resonance, lattice, alignment 1624
 
  • V. Forte, E. Benedetto, M. McAteer
    CERN, Geneva, Switzerland
  
  The CERN PS Booster is one of the machines of the LHC injector chain which will be upgraded within the LIU (LHC Injectors upgrade) project. The injection energy of the PSB will be increased to 160MeV in order to mitigate direct space charge effects, considered to be the main performance limitation, thus allowing to double the brightness for the LHC beams. In order to better predict the gain to be expected, space charge simulations are being carried out. Efforts to establish a realistic modeling of field and alignment errors aim at extending the basic model of the machine towards a more realistic one. Simulations of beam dynamics with strong direct space charge and realistic errors are presented and analysed in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI029  
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TUPRI031 A Precise Beam Dynamics Model of the PSI Injector 2 to Estimate the Intensity Limit cyclotron, simulation, extraction, acceleration 1630
 
  • A.M. Kolano, R.J. Barlow
    University of Huddersfield, Huddersfield, United Kingdom
  • A. Adelmann, C. Baumgarten
    PSI, Villigen PSI, Switzerland
  
  We describe a precise beam dynamics model of the production set up of the Injector 2 Cyclotron at the Paul Scherrer Institut (PSI). Injector 2 is a 72 MeV separate-sector cyclotron producing a high intensity proton beam up to 2.7 mA CW, which is then injected into the 590 MeV Ring Cyclotron. The model includes space charge and is calculated for optimised matched initial conditions. It has been verified with measurements. Based on this model we estimate the limits to the intensity obtainable from Injector 2. The precise beam dynamics model is based on the OPAL (Object Oriented Parallel Accelerator Library) simulation code, a tool for charged-particle optics calculations in large accelerator structures and beam lines including 3D space charge.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI031  
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TUPRI044 Investigation of Microbunching-instability in BERLinPro electron, simulation, linac, emittance 1662
 
  • S.D. Rädel, A. Jankowiak, A. Meseck
    HZB, Berlin, Germany
  
  Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Association
BERLinPro is using the new energy recovery linac technology. As, maintaining the low emittance and energy spread is of major importance in an ERL, the deep understanding and control of effects which can degrade the emittance and energy spread such as space charge effects are of interest. The microbunching caused by the longitudinal space charge forces can lead to an increase in emittance and energy spread in the arcs of the loop. In this contribution, the impacts of the microbunching instability on the beam quality and its implication for BERLinPro are discussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI044  
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TUPRI045 Beam Coupling Impedance Simulation in the Frequency Domain for the SIS100 Synchrotron impedance, coupling, dipole, synchrotron 1665
 
  • U. Niedermayer, O. Boine-Frankenheim
    TEMF, TU Darmstadt, Darmstadt, Germany
  • O. Boine-Frankenheim
    GSI, Darmstadt, Germany
  
  For the quantification of intensity thresholds due to coherent instabilities and beam induced heating in the FAIR synchrotron SIS100 a detailed knowledge of transverse and longitudinal beam coupling impedance is required. Due to the rather long proton and heavy-ion bunches, the relevant spectrum is below 100MHz. For the computation of beam coupling impedances in the low frequency regime, frequency domain methods are more advantageous than (explicit) time domain methods. We show the setup of a 2D finite element code that allows to compute the impedance for arbitrary longituninally homogeneous beam and structure shapes. Perfectly conducting pipes, a dispersive ferrite tube, and thin resistive beam pipe serve as test cases. The influence of the beam velocity on the coupling impedance is studied.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI045  
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TUPRI046 Dynamics of Ion Distributions in Beam Guiding Magnets ion, quadrupole, simulation, electron 1668
 
  • A. Markoviḱ, G. Pöplau, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • W. Hillert, D. Sauerland
    ELSA, Bonn, Germany
  • A. Meseck
    HZB, Berlin, Germany
  
  Funding: Supported by the German Federal Ministry of Education and Research (BMBF) under contract number 05K13HRC.
Ions generated by synchrotron radiation and collisions of the beam with the rest gas in the vacuum chamber could be a limiting factor for the operation of electron storage rings and Energy Recovery Linacs (ERL). In order to develop beam instability mitigation strategies, a deeper understanding of the ion-cloud behaviour is needed. Numerical simulations of the interaction between electron beams and parasitic ions verified with dedicated measurements can help to acquire that knowledge. This paper presents results of detailed simulations of the interaction in quadrupole magnets and drift sections of the Electron Stretcher Accelerator ELSA in Bonn. The focus is on the evaluation of the dynamics of different ion species and their characteristic distribution in quadrupole magnets. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI046  
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TUPRI048 A Map Approach for Electron Cloud Density in a Strong LHC Dipole electron, simulation, dipole, collider 1674
 
  • S. Petracca, A. Stabile
    U. Sannio, Benevento, Italy
  • A. Stabile
    INFN-Salerno, Baronissi, Salerno, Italy
  
  The luminosity is limited by the electron cloud effects in presently running and proposed future storage rings. The evolution of the electron density during the electron cloud formation can be reproduced using a bunch-to-bunch iterative map formalism. By performing simulation codes this approach has been used to obtain a numerical prediction of the coefficients in the map, while in the presence of a magnetic field an analytic formula has been obtained for the linear coefficient. The next goal is finding a theoretical prescription of the quadratic coefficient at least in the presence of magnetic dipole. Then it will be possible to reproduce, by using the map formalism, the dynamics of electron cloud without performing the simulations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI048  
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TUPRI059 The Proton Synchrotron Transverse impedance model impedance, simulation, kicker, proton 4096
 
  • S. Persichelli, N. Biancacci, S.S. Gilardoni, M. Migliorati, E. Métral, B. Salvant
    CERN, Geneva, Switzerland
  
  The current knowledge of the transverse impedance of the CERN Proton Synchrotron (PS) has been established by theoretical computations, electromagnetic simulations and beam-based measurements at different energies. The transverse coherent tune and phase advance shifts as a function of intensity have been measured in order to evaluate the total effective transverse impedance and its distribution in the accelerator. In order to understand the beam dynamics, the frequency dependence of the impedance budget has also been evaluated considering the individual contribution of several machine devices. 3D models of many PS elements have been realized to perform accurate impedance simulations, while resistive wall and indirect space charge impedances have been evaluated with theoretical and numerical computations. Finally comparisons between the total budget and the measurement results are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI059  
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TUPRI063 Electromagnetic Simulations for Non-ultrarelativistic Beams and Application to the CERN Low Energy Machines impedance, coupling, simulation, vacuum 1718
 
  • C. Zannini, N. Biancacci, T.L. Rijoff, G. Rumolo
    CERN, Geneva, Switzerland
  • T.L. Rijoff
    TU Darmstadt, Darmstadt, Germany
  
  In the framework of the PS-Booster upgrade project an accurate impedance model is needed in order to determine the effect on the beam stability and assess the impact of the new devices to be installed in the machine. CST 3-D EM simulations are widely used to estimate the impedance contribution of the different devices along the CERN accelerator complex. Unlike the highly relativistic case, in which the reliability of the EM solver has been proved in many specific cases by comparing simulations with analytical results, the nonrelativistic case has been so far not yet benchmarked. In order to use systematically CST 3-D EM simulations for the PS-Booster, or even lower energy machines like the antiproton decelerator ELENA, a validation campaign has been carried out. The main complication to single out the beam coupling impedance, as resulting from the interaction of the beam with the surroundings, consisted of removing reliably the strong contribution of the direct space charge of the source bunch, which is included in the EM calculation. The simulation results were then benchmarked with the analytical results for the case of a PEC cylindrical tube and of a ferrite loaded kicker.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI063  
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WEPRO061 Optimization of the SIS18 Injector Operation for FAIR acceleration, operation, experiment, controls 2088
 
  • D. Ondreka, H. Liebermann, B.R. Schlei
    GSI, Darmstadt, Germany
  
  In the FAIR accelerator complex, the existing synchrotron SIS18 will serve as an injector, supplying intense beams of heavy ions and protons for further acceleration in the synchrotron SIS100. In order to satisfy the intensity requirements for FAIR, SIS18 has to be operated routinely at the space charge limit. Particularly demanding requirements arise from the operation with medium charge state heavy ions due to the dynamic vacuum created by ions lost through charge exchange reactions. It is therefore crucial to avoid losses in SIS18 as much as possible while confining unavoidable losses onto low desorption surfaces. In this contribution we report on the ongoing activities related to minimizing the losses by means of a better quantitative understanding and control of the beam. This includes the development of more accurate theoretical models, benchmarked with machine experiments, as well as the practical integration of the models into the control system, using beam instrumentation data in the calculation of set values whenever possible.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRO061  
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WEPRO065 New Design of J-PARC Main Ring Injection System for High Beam Power Operation injection, kicker, septum, operation 2097
 
  • K. Fan, K. Ishii, H. Matsumoto, N. Matsumoto, T. Shibata, T. Sugimoto
    KEK, Ibaraki, Japan
  
  The present J-PARC main ring (MR) injection system has worked for 6 years since 2008, and the performance has been improved a lot by correcting the original design faults. But there are still problems in the existing injection system that affects the daily operation. In order to realize the MR beam power to the design limit, a high performance injection system is crucial. The remaining problems may have severe effects on high intensity beam, and become a big block to the realization of high beam power operation. Thus, upgrade the present injection system to satisfy the demands of high beam power operation is extremely important. The upgrade will redesign injection septa to obtain high performance, which will reduce the leakage field greatly. The kicker rise time will be reduced greatly by optimizing the configuration and using speed-up circuit. A compensation kicker magnet is being studied for reflection tail field cancelation. Careful 3D electromagnetic field simulations and 3D particle tracking are performed to ensure the accuracy of magnets design.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRO065  
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WEPRO066 Study for Space Charge effect in tune space at J-PARC MR coupling, resonance, quadrupole, simulation 2100
 
  • K. Ohmi, S. Igarashi
    KEK, Ibaraki, Japan
  • H. Harada
    JAEA, Ibaraki-ken, Japan
  • Y. Sato
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  
  Choice of tune operating point is serious for operation of high intensity proton machine. Space charge force induces tune spread and nonlinear resonance. Nonlinear resonances are also contained in accelerator lattice. We discuss optimization of operating point based on space charge simulation in J-PARC Main Ring.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRO066  
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WEPRO108 Electron Diffraction on VELA at Daresbury electron, gun, laser, experiment 2218
 
  • M. Surman
    STFC/DL/SRD, Warrington, Cheshire, United Kingdom
  • P. Aden, R.J. Cash, D.M.P. Holland, M.D. Roper
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
  • W.A. Bryan
    Swansea University, Swansea, Wales
  • J.A. Clarke, J.W. McKenzie
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • P.D. Lane, D.A. Wann
    University of York, York, United Kingdom
  • J.G. Underwood
    UCL, London, United Kingdom
  
  Accelerator based Ultrafast Electron Diffraction (UED) is a technique for static and dynamic structural studies in material and biological sciences. The recently commissioned VELA accelerator at the Daresbury Laboratory provides multi-MeV beams for science and industry and will provide a test bed for the UK electron diffraction community. We present the design of the diffractometer currently being installed on VELA which will allow capture of a single shot diffraction pattern with a 1 pC electron bunch and outline future options.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRO108  
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THPRO038 Energy-Silenced HGHG laser, FEL, bunching, electron 2946
 
  • E. Hemsing, G. Marcus, A. Marinelli
    SLAC, Menlo Park, California, USA
  • D. Xiang
    Shanghai Jiao Tong University, Shanghai, People's Republic of China
  
  We study the effect of longitudinal space charge on the correlated energy spread of a relativistic beam that has been microbunched for the emission of high harmonic radiation. We show that, in the case of microbunching induced by a laser modulator followed by a dispersive chicane, longitudinal space charge forces can act to significantly reduce the induced energy spread of the beam without a reduction in the harmonic bunching content. This effect may significantly relax constraints on the harmonic number achievable in HGHG FELs, which are otherwise limited by the induced energy spread from the laser.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO038  
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THPRO048 Emittance and Bunch Length Measurement of the Electron Beams from the NSRRC Photocathode Gun emittance, electron, gun, cavity 2974
 
  • A.P. Lee, M.C. Chou, N.Y. Huang, J.-Y. Hwang, W.K. Lau, C.C. Liang
    NSRRC, Hsinchu, Taiwan
  • P. Chiu, P. Wang
    NTHU, Hsinchu, Taiwan
  • Y. Hao
    BNL, Upton, Long Island, New York, USA
  
  A high brightness photo-injector is under development for single pass FEL research at NSRRC. The gun test facility (GTF) equipped with a photocathode rf gun a compensation solenoid, a S-band high power pulse klystron as well as a UV driver laser has been constructed for testing the photocathode rf gun. The gun is fabricated in house and being tested at the GTF. Since the transverse emittance is a key property of the electron beam from the rf gun, multi-slit method is used to characterize the transverse emittance of the electron beam. Another key property of the electron beam is bunch length. An S-band three-cell deflecting cavity is designed to measure the bunch length. The setup and results of emittance measurement as well as the structure design of the deflecting cavity is reported in this contribution.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO048  
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THPRO058 Study of the “Particle-in-Cell” Induced Noise on High Intensity Beams emittance, simulation, synchrotron, resonance 3005
 
  • F. Kesting, G. Franchetti
    GSI, Darmstadt, Germany
  • U. Ratzinger
    IAP, Frankfurt am Main, Germany
  
  Numerical noise in PIC codes produces artifacts which affects long term beam simulations needed for accelerator as the SIS100. A detailed study on the effect of numerical noise occurring in multi-particle tracking codes is presented. The influence of the granularity of particle distributions and the fineness of the meshes of Poisson solvers on the particle dynamics was studied. These results are used to discuss the effect of the PIC numerical noise in a long term space charge benchmarking study.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO058  
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THPRO072 Field Parametrisation for the ESS Superconducting Cavities cavity, linac, simulation, HOM 3044
 
  • T. Lindqvist
    Lund University, Lund, Sweden
  • E. Laface
    ESS, Lund, Sweden
  
  Here we present a method for constructing a parametrization of the electric field in the superconducting elliptic cavities of the ESS linac. The parametrization is done by replicating the electric field from measured data using trigonometric and exponential functions. The field generated by the parameters exhibits a mean error of 0.28% ( maximum error of 3.8% and s.t.d. error 1.1%), with the advantage of only taking up a fraction of the required data. The field in the entire cavity is extrapolated by combining the Maxwell equations with the parametrized form of the field. We also present particle simulations based on the parametrization model to showcase some typical accelerator behaviour. Additionally we present a small extension of the parametrization method to also model spoke cavities.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO072  
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THPRO081 Simulation and Observation of Driven Beam Oscillations with Space Charge in the CERN PS Booster simulation, dipole, quadrupole, focusing 3073
 
  • M. McAteer, J.M. Belleman, E. Benedetto, C. Carli, A. Findlay, B. Mikulec, R. Tomás
    CERN, Geneva, Switzerland
  
  Funding: This project has been supported by a Marie Curie Early Initial Training Network Fellowship of the European Community's Seventh Framework Programme, contract number (PITN-GA-2011-289485-OPAC).
As part of the LHC Injector Upgrade project, the CERN PS Booster will operate at higher injection and extraction energies and with nearly a factor of two increase in beam brightness. In order to better understand the machine’s limitations, a campaign of nonlinear optics measurements from turn-by-turn trajectory measurements is planned for after Long Shutdown 1. The goal of this work is to establish an efficient procedure for implementing a resonance compensation scheme after the machine’s injection energy is increased. The trajectory measurement system is expected initially to require high intensity beam in order to have good position measurement resolution, so understanding space charge effects will be important for optics analysis. We present the results of simulations of driven beam oscillations with space charge effects, and comparison with trial beam trajectory measurements. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO081  
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THPRO092 Stochastic Noise Effects in High Current PIC Simulation emittance, lattice, simulation, solenoid 3101
 
  • I. Hofmann, O. Boine-Frankenheim
    TEMF, TU Darmstadt, Darmstadt, Germany
  • O. Boine-Frankenheim, I. Hofmann
    GSI, Darmstadt, Germany
  
  The numerical noise inherent to particle-in-cell simulation of 3D high intensity bunched beams is studied with the TRACEWIN code and compared with the analytical model by Struckmeier (1994). The latter assumes the six-dimensional rms emittance or rms entropy growth can be related to Markov type stochastic processes due to temperature anisotropy and the artificial "collisions" caused by using macro-particles and calculating the space charge effect. Our entropy growth confirms the dependency on bunch temperature anisotropy as predicted by Struckmeier. However, we also find noise generation by the non-Liouvillean effect of the Poisson solver grid, which exists in periodic focusing systems even when local temperature anisotropy is absent - contrary to predictions by Struckmeier's model.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO092  
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THPRO094 Large Scale Particle Tracking and the Application in the Simulation of the RFQ Accelerator rfq, software, simulation, emittance 3107
 
  • L. Du, Q.Z. Xing
    TUB, Beijing, People's Republic of China
  • Y.K. Batygin
    LANL, Los Alamos, New Mexico, USA
  • Y. He, L. Yang
    IMP, Lanzhou, People's Republic of China
  • J. Xu, R. Zhao
    IS, Beijing, People's Republic of China
  
  Large scale particle tracking is important for the design and optimization of the Radio-frequency Quadrupole (RFQ) accelerator. In this paper, we present RFQ simulation results of new parallel software named LOCUS3D, which is developed at Institute of Software, Chinese Academy of Sciences. It is based on Particle-In-Cell method and calculates three-dimensional space charge field by an efficient parallel fast Fourier transform method. A RFQ accelerator in Tsinghua University is simulated by tracking 100 million macro particles. This RFQ is designed to accelerate protons from 50 keV to 3 MeV, with peak beam current of 50 mA. As large number of particles been simulated, more accurate and detailed information have been obtained.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO094  
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THPRO097 Space-charge Neutralization of 750-keV H− Beam at LANSCE emittance, beam-transport, simulation, ion 3116
 
  • Y.K. Batygin, C. Pillai, L. Rybarcyk
    LANL, Los Alamos, New Mexico, USA
  
  The injector part of Los Alamos Neutron Science Center (LANSCE) includes 750-keV H− beam transport located upstream of the Drift Tube Linac. Space charge effects play an important role in the beam transport therein. A series of experiments were performed to determine the level of beam space charge neutralization, and time required for neutralization. Measurements performed at different places along the structure indicate significant variation of neutralized space charge beam dynamics along the beamline. Results of measurements were compared with numerical simulations using macroparticle method and envelope equations to determine values of the effective beam current after neutralization, and effective beam emittance, required for beam tuning.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO097  
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THPME003 A Precise Determination of the Core-halo Limit emittance, linac, extraction, instrumentation 3208
 
  • P.A.P. Nghiem, N. Chauvin, D. Uriot, M. Valette
    CEA/DSM/IRFU, France
  • W. Simeoni
    IF-UFRGS, Porto Alegre, Brazil
  
  For high-intensity beams, the dynamics of the dense core is different from that of the much less dense halo. Relations between core emittance growth and halo generation are often studied, halo scraping often experienced and halo re-formation observed. For all that, a clear distinction between the core and the halo parts does not exist. This paper proposes a new method for precisely determining the core-halo limit applicable to any particle distribution type. Once this limit is known, the importance of the halo relative to the core can be precisely quantified. The core-halo limit determination may be easily extended to the nD phase space, allowing the definition of emittance and Twiss parameters for the core and the halo separately.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME003  
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THPME019 LIPAc, the 125mA / 9MeV / CW Deuteron IFMIF’s Prototype Accelerator: What Lessons Have We Learnt from LEDA? rfq, linac, proton, emittance 3256
 
  • F. Scantamburlo, J. Knaster, Y. Okumura
    IFMIF/EVEDA, Rokkasho, Japan
  • N. Chauvin, R. Gobin, P.A.P. Nghiem
    CEA/DSM/IRFU, France
  • A. Kasughai, H. Shidara
    Japan Atomic Energy Agency (JAEA), International Fusion Energy Research Center (IFERC), Rokkasho, Kamikita, Aomori, Japan
  
  The Engineering Validation and Engineering Design Activities (EVEDA) phase of IFMIF aims at running a 9 MeV / 125 mA / CW deuteron accelerator to demonstrate the feasibility of IFMIF’s 40 MeV / 125 mA / CW accelerator with components mainly designed and constructed in European labs. LEDA was operated successfully in 1999-2001 as a 6.7 MeV / 100 mA / CW proton accelerator with high availability. The present paper assesses the experience gained in LEDA and explains how LIPAc, the IFMIF prototype accelerator, is inheriting its role of breaking through technological boundaries.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME019  
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THPME056 A Space-charge Compatible "Tomography" of Beam Phase-space Distributions experiment, simulation, beam-transport, focusing 3358
 
  • N. Pichoff
    CEA/DSM/IRFU, France
  • A. Lasheen
    CERN, Geneva, Switzerland
  
  The well-known 3-gradient method allows accessing to a beam RMS emittance and Twiss parameters at a position A by measuring its rms size at a downstream position B with at least 3 different transport conditions from A to B. We suggest extending this method to access to a beam phase-space distribution model at A from beam profiles measured at B. We propose to use an iterative method which consists in: - defining a parametric model describing the beam distribution in 4D transverse phase-space at a position A, - adjusting iteratively the model parameters by minimizing the difference between beam profiles measured at B and these obtained by transporting the beam generated according to the model with TraceWIN code from A to B. This method allows taking into account space-charge and other transport non-linearities.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME056  
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THPME139 Emittance Measurement with Wire Scanners at CADS MEBT1 emittance, rfq, quadrupole, linac 3575
 
  • H. Geng, P. Cheng, C. Meng, S. Pei, B. Sun, H.J. Wang, B. Xu, F. Yan, Y.L. Zhao
    IHEP, Beijing, People's Republic of China
  
  The C-ADS project has started beam commissioning. The ion source and LEBT has been commissioned successfully, while the RFQ is under conditioning. The Medium Energy Beam Transport line-1 (MEBT) is the place where extensive beam parameter measurement will be carried out. Beam emittance is one of the most critical parameters which have to characterized. In the C-ADS injector-I, the MEBT-1 has installed three wire scanners to measure the beam sizes. The transverse emittance measurement method using the wire scanners will be discussed in detail in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME139  
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THPRI032 Study of a RF Gun with a Thermoionic Cathode gun, cavity, injection, simulation 3837
 
  • A.S. Setty, A.S. Chauchat, D. Fasse, D. Jousse, P. Sirot
    Thales Communications & Security (TCS), Gennevilliers Cedex, France
  
  The low energy part of our pre injectors* is made up of a 90 kV DC thermoionic triode gun, followed by a 500 MHz sub harmonic prebuncher and a 3 GHz prebuncher. These two cavities are respectively fed with 500 W, a modulation of ± 25 kV, and 90 W corresponding to a ± 10 kV. The gun grid is modulated within a 500 MHz signal. The initial 1 ns phase extension at the gun level is reduced, at the buncher entry, to 40 ps for 75% of the gun current. This study proposes to replace the gun and the two cavities by a RF gun integrated in a modulated cavity at 200 MHz followed by a drift in order to bunch the beam. This study will compare the beam dynamics simulations for these two cases.
*A. Setty et al, "Design and Construction of Turnkey Linacs as Injectors for Light Sources", Proceedings IPAC 2012, USA, Louisiana, May 2012. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI032  
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THPRI065 Effects of Beam Loading and Higher-order Modes in RF Cavities for Muon Ionization Cooling cavity, beam-loading, plasma, higher-order-mode 3921
 
  • M. Chung, A.V. Tollestrup, K. Yonehara
    Fermilab, Batavia, Illinois, USA
  • B.T. Freemire
    IIT, Chicago, Illinois, USA
  • F. Marhauser
    Muons, Inc, Illinois, USA
  
  Envisioned muon ionization cooling channel is based on vaccum and/or gas-filled RF cavities of frequencies of 325 and 650 MHz. In particular, to meet the luminosity requirement for a muon collider, the muon beam intensity should be on the order of 1012 muons per bunch. In this high beam intensity, transient beam loading can significantly reduce the accelerating gradients and deteriorate the beam quality. We estimate this beam loading effect using an equivalent circuit model. For gas-filled cavity case, the beam loading is compared with plasma loading. We also investigate the excitation of higher-order modes and their effects on the performance of the cavity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI065  
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