Keyword: simulation
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SAPLG01 Advances in Simulation of High Brightness/High Intensity Beams emittance, controls, linac, electron 1
 
  • J. Qiang
    LBNL, Berkeley, California, USA
  
  High brightness/high intensity beams play an important role in accelerator based applications by driving x-ray free electron laser (FEL) radiation, producing spallation neutrons and neutrinos, and generating new particles in high energy colliders. In this paper, we report on recent advances in modeling the high brightness electron beam with application to the next generation FEL light sources and in modeling space-charge effects in high intensity proton accelerators.  
slides icon Slides SAPLG01 [3.914 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SAPLG01  
About • paper received ※ 02 November 2018       paper accepted ※ 19 November 2018       issue date ※ 26 January 2019  
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SAPAF02 Optimization of Heavy-Ion Synchrotrons Using Nature-Inspired Algorithms and Machine Learning injection, emittance, synchrotron, space-charge 15
 
  • S. Appel, W. Geithner, S. Reimann, M. Sapinski, R. Singh, D.M. Vilsmeier
    GSI, Darmstadt, Germany
  
  The application of machine learning and nature-inspired optimization methods, like for example genetic algorithms (GA) and particle swarm optimization (PSO) can be found in various scientific/technical areas. In recent years, those approaches are finding application in accelerator physics to a greater extent. In this report, nature-inspired optimization as well as the machine learning will be shortly introduced and their application to the accelerator facility at GSI/FAIR will be presented. For the heavy-ion synchrotron SIS18 at GSI, the multi-objective GA/PSO optimization resulted in a significant improvement of multi-turn injection performance and subsequent transmission for intense beams. An automated injection optimization with genetic algorithms at the CRYRING@ESR ion storage ring has been performed. The usage of machine learning for a beam diagnostic application, where reconstruction of space-charge distorted beam profiles from ionization profile monitors is performed, will also be shown. First results and the experience gained will be presented.  
slides icon Slides SAPAF02 [2.642 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SAPAF02  
About • paper received ※ 16 October 2018       paper accepted ※ 27 January 2019       issue date ※ 26 January 2019  
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SAPAF03 Comparison of Model-Based and Heuristic Optimization Algorithms Applied to Photoinjectors Using Libensemble cavity, space-charge, gun, solenoid 22
 
  • N.R. Neveu
    IIT, Chicago, Illinois, USA
  • S. T. P. Hudson, J.M. Larson
    ANL, Argonne, Illinois, USA
  • L.K. Spentzouris
    Illinois Institute of Technology, Chicago, Illinois, USA
  
  Funding: U.S. DOE, OS, contract DE-AC02-06CH11357 and grant DE-SC0015479.
Genetic algorithms are common and often used in the accelerator community. They require large amounts of computational resources and empirical adjustment of hyperparameters. Model based methods are significantly more efficient, but often labeled as unreliable for the nonlinear or unsmooth problems that can be found in accelerator physics. We investigate the behavior of both approaches using a photoinjector operated in the space charge dominated regime. All optimization runs are coordinated and managed by the Python library libEnsemble, which is developed at Argonne National Laboratory. 		 
slides icon Slides SAPAF03 [0.653 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SAPAF03  
About • paper received ※ 11 November 2018       paper accepted ※ 19 November 2018       issue date ※ 26 January 2019  
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SAPAF04 Single Objective Genetic Optimization of an 85% Efficient Klystron klystron, cavity, electron, bunching 25
 
  • A. Jensen, J.J. Petillo
    Leidos Corp, Billerica, MA, USA
  • R.L. Ives, M.E. Read
    CCR, San Mateo, California, USA
  • J. Neilson
    SLAC, Menlo Park, California, USA
  
  Overall efficiency is a critical priority for the next generation of particle accelerators as they push to higher and higher energies. In a large machine, even a small increase in efficiency of any subsystem or component can lead to a significant operational cost savings. The Core Oscillation Method (COM) and Bunch-Align-Compress (BAC) method have recently emerged as a means to greatly increase the efficiency of the klystron RF source for particle accelerators. The COM and BAC methods both work by uniquely tuning klystron cavity frequencies such that more particles from the anti-bunch are swept into the bunch before power is extracted from the beam. The single objective genetic algorithm from Sandia National Laboratory’s Dakota optimization library is used to optimize both COM and BAC based klystron designs to achieve 85% efficiency. The COM and BAC methods are discussed. Use of the Dakota optimization algorithm library from Sandia National Laboratory is discussed. Scalability of the optimization approach to High Performance Computing (HPC) is discussed. The optimization approach and optimization results are presented.  
slides icon Slides SAPAF04 [1.476 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SAPAF04  
About • paper received ※ 16 October 2018       paper accepted ※ 19 November 2018       issue date ※ 26 January 2019  
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SAPAG03 Mode-Analysis Methods for the Study of Collective Instabilities in Electron-Storage Rings cavity, damping, impedance, radiation 30
 
  • M. Venturini
    LBNL, Berkeley, California, USA
  
  We report on recent progress on the application of mode analysis to the study of collective instabilities in electron storage rings including Higher Harmonic RF Cavities (HHCs). The focus is on transverse instabilities in the presence of a dominant resistive-wall impedance, a problem of particular relevance to the new generation of diffraction-limited light sources. The secular equation for the system eigenvalues is solved after applying a regularizing transformation, a key step to obtaining numerically accurate solutions. We provide a demonstration that for vanishing chromaticity and in the absence of radiation damping the beam motion is always unstable. This is in contrast to the more conventional Transverse-Mode-Coupling Instability (TMCI) without HHCs, which is known to exhibit a well defined instability threshold.  
slides icon Slides SAPAG03 [2.261 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SAPAG03  
About • paper received ※ 18 October 2018       paper accepted ※ 24 October 2018       issue date ※ 26 January 2019  
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SUPAF04 Symplectic and Self-Consistent Algorithms for Particle Accelerator Simulation plasma, space-charge, betatron, resonance 42
 
  • T. Planche, P. M. Jung
    TRIUMF, Vancouver, Canada
  
  This paper is a review of algorithms, applicable to particle accelerator simulation, which share the following two characteristics: (1) they preserve to machine precision the symplectic geometry of the particle dynamics, and (2) they track the evolution of the self-field consistently with the evolution of the charge distribution. This review includes, but is not limited to, algorithms using a Particle-in-Cell discretization scheme. At the end of this review we discuss to possibility to derived algorithms from an electrostatic Hamiltonian.  
slides icon Slides SUPAF04 [0.424 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAF04  
About • paper received ※ 19 October 2018       paper accepted ※ 24 October 2018       issue date ※ 26 January 2019  
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SUPAF06 Simulations of Coherent Electron Cooling With Free Electron Laser Amplifier and Plasma-Cascade Micro-Bunching Amplifier electron, FEL, plasma, bunching 52
 
  • J. Ma, V. Litvinenko, G. Wang
    BNL, Upton, Long Island, New York, USA
  • V. Litvinenko
    Stony Brook University, Stony Brook, USA
  
  SPACE is a parallel, relativistic 3D electromagnetic Particle-in-Cell (PIC) code used for simulations of beam dynamics and interactions. An electrostatic module has been developed with the implementation of Adaptive Particle-in-Cloud method. Simulations performed by SPACE are capable of various beam distribution, different types of boundary conditions and flexible beam line, as well as sufficient data processing routines for data analysis and visualization. Code SPACE has been used in the simulation studies of coherent electron cooling experiment based on two types of amplifiers, the free electron laser (FEL) amplifier and the plasma-cascade micro-bunching amplifier.  
slides icon Slides SUPAF06 [1.260 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAF06  
About • paper received ※ 15 October 2018       paper accepted ※ 24 October 2018       issue date ※ 26 January 2019  
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SUPAF07 High-Fidelity Three-Dimensional Simulations of Thermionic Energy Converters electron, space-charge, cathode, operation 59
 
  • N.M. Cook, J.P. Edelen, C.C. Hall, M.V. Keilman, P. Moeller, R. Nagler
    RadiaSoft LLC, Boulder, Colorado, USA
  • J.-L. Vay
    LBNL, Berkeley, California, USA
  
  Funding: This work is supported the US DOE Office of Science, Office of High Energy Physics: DE-SC0017162.
Thermionic energy converters (TEC) are a class of thermoelectric devices, which promise improvements to the efficiency and cost of both small- and large-scale electricity generation. A TEC is comprised of a narrowly-separated thermionic emitter and an anode. Simple structures are often space-charge limited as operating temperatures produce currents exceeding the Child-Langmuir limit. We present results from 3D simulations of these devices using the particle-in-cell code Warp, developed at Lawrence Berkeley National Lab. We demonstrate improvements to the Warp code permitting high fidelity simulations of complex device geometries. These improvements include modeling of non-conformal geometries using mesh refinement and cut-cells with a dielectric solver. We also consider self-consistent effects to model Schottky emission near the space-charge limit for arrays of shaped emitters. The efficiency of these devices is computed by modeling distinct loss channels, including kinetic losses, radiative losses, and dielectric charging. We demonstrate many of these features within an open-source, browser-based interface for running 3D electrostatic simulations with Warp, including design and analysis tools, as well as streamlined submission to HPC centers. 		 
slides icon Slides SUPAF07 [6.097 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAF07  
About • paper received ※ 01 November 2018       paper accepted ※ 19 November 2018       issue date ※ 26 January 2019  
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SUPAF08 Particle-in-Cell Simulation of a Bunched Electrons Beam Acceleration in a TE113 Cylindrical Cavity Affected by a Static Inhomogeneous Magnetic Field electron, acceleration, cavity, resonance 64
 
  • E.A. Orozco
    UIS, Bucaramanga, Colombia
  • J.R. Beltrán, J.D. González, V.E. Vergara
    UMAG, Santa Marta, Colombia
  
  Funding: Universidad Industrial de Santander vice-rectory of research and extension. Mobility program N° Application: 2349
The results of the relativistic full electromagnetic Particle-in-cell (PIC) simulation of a bunched electrons beam accelerated in a TE113 cylindrical cavity in the presence of a static inhomogeneous magnetic field are presented. This type of acceleration is known as Spatial AutoResonance Acceleration (SARA)*. The magnetic field profile is such that it keeps the electrons beam in the acceleration regime along their trajectories. Numerical experiments of bunched electrons beam with the concentrations in the range 108 -109 cm-3 in a linear TE113 cylindrical microwave field of a frequency of 2.45GHz and an amplitude of 15kV /cm show that it is possible accelerate the bunched electrons up to energies of 250keV without serious defocalization effect. A comparison between the data obtained from the full electromagnetic PIC simulations and the results derived from the relativistic Newton-Lorentz equation in a single particle approximation is carried out. This acceleration scheme can be used to produce hard x-ray**.
* Dugar-Zhabon, V. D., & Orozco, E. A. (2009).Physical Review Special Topics-Accelerators and Beams, 12(4), 041301.
** Dugar-Zhabon, V. D., & Orozco, E. A. (2017). (USA Patent: 9,666, 403 )
 		 
slides icon Slides SUPAF08 [1.358 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAF08  
About • paper received ※ 21 October 2018       paper accepted ※ 27 January 2019       issue date ※ 26 January 2019  
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SUPAF09 Sparse Grid Particle-in-Cell Scheme for Noise Reduction in Beam Simulations electron, plasma, target, damping 71
 
  • A.J. Cerfon
    Courant Institute of Mathematical Sciences, New York University, New York, USA
  • L.F. Ricketson
    LLNL, Livermore, California, USA
  
  The complexity of standard solvers grows exponentially with the number of dimensions of the underlying equations. This issue is particularly acute for continuum solvers, which need to discretize the six-dimensional phase-space distribution function, and whose run times are consequently large even for a moderate number of grid points for each dimension. Particle-in-Cell (PIC) schemes are a popular alternate approach to continuum methods, because they only discretize the three-dimensional physical space and are therefore less subject to the curse of dimensionality. Even if so, PIC solvers still have large run times, because of the statistical error which is inherent to particle methods and which decays slowly with the number of particles per cell. In this talk, we will present a new scheme to address the curse of dimensionality and at the same time reduce the numerical noise of PIC simulations. Our PIC scheme is inspired by the sparse grids combination technique, a method invented to reduce grid based error when solving high dimensional partial differential equations [1]. The technique, when applied to the PIC method, has two benefits: 1) it almost eliminates the dependence of the grid based error on dimensionality, just like in a standard sparse grids application; 2) it lowers the statistical error significantly, because the sparse grids have larger cells, and thus a larger number of particles per cell for a given total number of particles. We will analyze the performance of our scheme for standard test problems in beam physics. We will demonstrate remarkable speed up for a certain class of problems, and less impressive performance for others. The latter will allow us to identify the limitations of our scheme and explore ideas to address them.
[1] Griebel M et al. 1990 A combination technique for the solution of sparse grid problems Iterative Methods in Linear Algebra ed R Bequwens and P de Groen (Amsterdam: Elsevier) pp 263-81 		 
slides icon Slides SUPAF09 [1.848 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAF09  
About • paper received ※ 19 October 2018       paper accepted ※ 19 November 2018       issue date ※ 26 January 2019  
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SUPAF10 Reconstruction of Particle Distributions at RFQ Exit at SNS Beam Test Facility quadrupole, rfq, emittance, lattice 76
 
  • Z.L. Zhang
    ORNL RAD, Oak Ridge, Tennessee, USA
  • A.V. Aleksandrov, S.M. Cousineau
    ORNL, Oak Ridge, Tennessee, USA
  
  Fluctuations of beam parameters and uncertainties of quadrupole gradients during measurements have effects on the reconstruction of initial particle distributions. To evaluate these effects, the concept of a distribution discrepancy is proposed. Results suggest effects of fluctuations of beam parameters are small, while uncertainties of quadrupole gradients are the main factors that affect the reconstructed distributions. By comparing the measured distributions with distributions produced by tracking the reconstructed initial distributions, it is proved that the real or quasi-real (closest to real) initial distribution can be obtained as long as the minimum distribution discrepancy is found.  
slides icon Slides SUPAF10 [8.261 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAF10  
About • paper received ※ 18 October 2018       paper accepted ※ 27 January 2019       issue date ※ 26 January 2019  
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SUPAG01 Space Charge and Transverse Instabilities at the CERN SPS and LHC coupling, optics, space-charge, impedance 80
 
  • E. Métral, D. Amorim, G. Arduini, H. Bartosik, E. Benedetto, H. Burkhardt, K.S.B. Li, A. Oeftiger, D. Quatraro, G. Rumolo, B. Salvant, C. Zannini
    CERN, Geneva, Switzerland
  
  At the CERN accelerator complex, it seems that only the highest energy machine in the sequence, the LHC, with space charge (SC) parameter close to one, sees the predicted beneficial effect of SC on transverse coherent instabilities. In the other circular machines of the LHC injector chain (PSB, PS and SPS), where the SC parameter is much bigger than one, SC does not seem to play a major (stabilising) role, and it is maybe the opposite in the SPS. All the measurements and simulations performed so far in both the SPS and LHC will be reviewed and analysed in detail.  
slides icon Slides SUPAG01 [37.523 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAG01  
About • paper received ※ 20 October 2018       paper accepted ※ 19 November 2018       issue date ※ 26 January 2019  
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SUPAG05 Muon Background Studies for Beam Dump Operation of the K12 Beam Line at CERN proton, experiment, target, background 93
 
  • M.S. Rosenthal, D. Banerjee, J. Bernhard, M. Brugger, N. Charitonidis, B. Döbrich, L. Gatignon, A. Gerbershagen, E. Montbarbon, B. Rae, M.W.U. Van Dijk
    CERN, Geneva, Switzerland
  • T. Spadaro
    INFN/LNF, Frascati, Italy
  
  In the scope of the Physics Beyond Colliders study at CERN a future operation of the NA62 experiment in beam dump mode is discussed, enabling the search for dark sector particles, e.g. heavy neutral leptons, dark photons and axions. For this purpose, the 400 GeV/c primary proton beam, extracted from the SPS, will be dumped on a massive dump collimator located in the front end of the K12 beam line. Muons originating from interactions and decays form a potential background for this kind of experiment. To reduce this background, magnetic sweeping within the beam line is employed. In this contribution, the muon production and transport has been investigated with the simulation framework G4beamline. The high computational expense of the muon production has been reduced by implementing sampling methods and parametrizations to estimate the amount of high-energy muons and efficiently study optimizations of the magnetic field configuration. These methods have been benchmarked with measured data, showing a good qualitative agreement. Finally, first studies to reduce the muon background by adapting the magnetic field configuration are presented, promising a potential background reduction by a factor four.  
slides icon Slides SUPAG05 [1.885 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAG05  
About • paper received ※ 19 October 2018       paper accepted ※ 28 January 2019       issue date ※ 26 January 2019  
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SUPAG06 Simulation Challenges for eRHIC Beam-Beam Study electron, proton, damping, cavity 99
 
  • Y. Luo
    BNL, Upton, Long Island, New York, USA
  • Y. Hao
    FRIB, East Lansing, USA
  • J. Qiang
    LBNL, Berkeley, California, USA
  • Y. Roblin
    JLab, Newport News, Virginia, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The 2015 Nuclear Science Advisory Committee Long Rang Plan identified the need for an electron-ion collider facility as a gluon microscope with capabilities beyond those of any existing accelerator complex. To reach the required high energy, high luminosity, and high polarization, the eRHIC design based on the existing heady ion and polarized proton collider RHIC adopts a very small beta-function at the interaction point, a high collision repetition rate, and a novel hadron cooling scheme. Collision with a full crossing angle of 22 mrad and crab cavities for both electron and proton rings are required. In this article, we will present the high priority R&D items related to beam-beam interaction for the current eRHIC design, the simulation challenges, and our plans to address them. 		 
slides icon Slides SUPAG06 [2.395 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAG06  
About • paper received ※ 18 October 2018       paper accepted ※ 03 December 2018       issue date ※ 26 January 2019  
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SUPAG10 Design Study of a Fast Kicker Magnet Applied to the Beamline of a Proton Therapy Facility kicker, proton, vacuum, cyclotron 110
 
  • W.J. Han
    Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People’s Republic of China
  • X. Liu, B. Qin
    HUST, Wuhan, People’s Republic of China
  
  Funding: Huazhong University Of Science And Technology
A proton therapy facility based on an isochronous superconducting cyclotron is under development in HUST (Huazhong University of Science and Technol-ogy). A fast kicker magnet will be installed in the up-stream of the degrader to perform the beam switch function by kicking the proton beam to the down-stream beam stop. The rising and falling time of the kicker is about 100us, and the maximum repetition rate is 500Hz. This paper introduces simulation and opti-mization of the eddy current and dynamic magnetic field of the fast kicker, by using FEM code OPERA-3D. For kicker materials, laminated steel and soft ferrite are compared and the MnZn ferrite is chosen. Design-ing considerations includes the eddy current effect, field hysteresis, and mechanical structure of the kicker will also be introduced. 		 
slides icon Slides SUPAG10 [1.184 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAG10  
About • paper received ※ 19 October 2018       paper accepted ※ 04 December 2018       issue date ※ 26 January 2019  
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SUPLG01 Computational Accelerator Physics: On the Road to Exascale space-charge, plasma, optics, radiation 113
 
  • R.D. Ryne
    LBNL, Berkeley, USA
  
  The first conference in what would become the ICAP series was held in 1988. At that time the most powerful computer in the world was a Cray YMP with 8 processors and a peak performance of 2 gigaflops. Today the fastest computer in the world has more than 2 million cores and a theoretical peak performance of nearly 200 petaflops. Compared to 1988, performance has increased by a factor of 100 million, accompanied by huge advances in memory, networking, big data management and analytics. By the time of the next ICAP in 2021 we will be at the dawn of the Exascale era. In this talk I will describe the advances in Computational Accelerator Physics that brought us to this point and describe what to expect in regard to High Performance Computing in the future. This writeup as based on my presentation at ICAP’18 along with some additional comments that I did not include originally due to time constraints.  
slides icon Slides SUPLG01 [25.438 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPLG01  
About • paper received ※ 14 November 2018       paper accepted ※ 07 December 2018       issue date ※ 26 January 2019  
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MOPAF02 Realistic Modeling of the Muon g-2 Experiment Beamlines at Fermilab target, storage-ring, experiment, proton 134
 
  • D. Tarazona, M. Berz, K. Makino
    MSU, East Lansing, Michigan, USA
  • D. Stratakis, M.J. Syphers
    Fermilab, Batavia, Illinois, USA
  • M.J. Syphers
    Northern Illinois University, DeKalb, Illinois, USA
  
  Funding: This work is supported by the U.S. Department of Energy under Award No. DE-FG02-08ER41546, by the PhD Accelerator Program at Fermilab, and by a Strategic Partnership Grant from the MSU Foundation.
The main goal of the Muon g-2 Experiment at Fermilab (E989) is to measure the muon anomalous magnetic moment (a, also dubbed as the "anomaly’’) to unprecedented precision. This new measurement will allow to test the completeness of the Standard Model (SM) and to validate other theoretical models beyond the SM. Simulations of the beamlines from the pion production target to the entrance of the g-2 Storage Ring using COSY INFINITY contribute to the understanding and characterization of the muon beam production in relation to the statistical and systematics uncertainties of the E989 measurement. The effect of nonlinearites from fringe fields and high-order contributions on the beam delivery system performance are considered, as well as interactions with the beamline elements apertures, particle decay channels, spin dynamics, and beamline misalignments. 		 
slides icon Slides MOPAF02 [14.110 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-MOPAF02  
About • paper received ※ 22 October 2018       paper accepted ※ 28 January 2019       issue date ※ 26 January 2019  
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MOPAF03 Polarization Lifetime in an Electron Storage Ring, an Ergodic Approach in eRHIC EIC polarization, electron, storage-ring, resonance 140
 
  • F. Méot
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy
Electron polarization in a storage ring is subject to two very long term effects: Sokolov-Ternov polarization and depolarization by diffusion. This leads to an equilibrium state over a very long time scale, and, simulation-wise, is highly CPU-time and -memory consuming. Simulations aimed at determining optimal ring storage energy in an electron-ion collider in this context, are always based on tracking bunches with thousands of particles, and in addition for short time scales in comparison, due to HPC limitations. Based on considerations of ergodicity of electron bunch dynamics in the presence of synchrotron radiation, and on the very slow depolarization aimed at in a collider, tracking a single particle instead is investigated, here. This saves a factor of more than 2 orders of magnitudes in the parameter CPU-time*Memory-allocation, it allows much longer tracking and thus improved accuracy on the evaluation of polarization and time constants. The concept is illustrated with polarization lifetime and equilibrium polarization simulations at the eRHIC electron-ion collider. 		 
slides icon Slides MOPAF03 [1.758 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-MOPAF03  
About • paper received ※ 23 October 2018       paper accepted ※ 27 January 2019       issue date ※ 26 January 2019  
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MOPAG01 Plasma Wakefield Start to End Acceleration Simulations From Photocathode to FEL With Simulated Density Profiles plasma, electron, acceleration, FEL 154
 
  • A. Marocchino
    INFN/LNF, Frascati (Roma), Italy
  
  Plasma Wakefield acceleration is a promising new acceleration technique that profit by a charged bunch, e.g. an electron bunch, to break the neutrality of a plasma channel to produce a wake where a trailing bunch is eventually accelerated. The quest to achieve extreme gradient conserving high brightness has prompted to a variety of new approaches and techniques. Most of the proposed schemes are however limited to the only plasma channel, assuming in the vast majority of cases, ideal scenarios (e.g. ideal bi-gaussian bunches and uniform density plasma channels). Realistic start-to-end simulations from the photocathode to a FEL via a plasma accelerating section are a fundamental step to further investigate realistic scheme possibilities, the underlying physics and future applications. To remove ideal simplifications, the SPARC_LAB simulation team is simulating bunches from the photo-cathode and tracking them all the way to the plasma. Similarly, the density profiles, where bunches evolve and accelerate, are calculated with a magneto-hydrodynamic code. The density profile is imported into the particle in cell codes used to calculate the particle evolution within the plasma section. The use of a multitude of codes, involving different architectures, physical units and programming languages, made necessary the definition of code interfacing and pipe-processes to ensure a proper pipeline of tools that are traditionally used in different fields are do not often come across. By combining the different numerical codes (particle tracker, particle in cell, magneto-hydrodynamics and FEL codes) we could propose a first realistic start-to-end simulation from the photo-cathode to a FEL lasering for a possible upcoming Italian PWFA-FEL facility. Such a work is conducted with a great focus on code reliability and data reproducibility. The Italian PWFA experimental team uses a capillary to control and tailor the plasma density profile, we could perform preliminary code comparison and  
slides icon Slides MOPAG01 [34.540 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-MOPAG01  
About • paper received ※ 16 October 2018       paper accepted ※ 24 October 2018       issue date ※ 26 January 2019  
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MOPAG02 Efficient Modeling of Laser Wakefield Acceleration Through the PIC Code Smilei in CILEX Project laser, plasma, electron, electromagnetic-fields 160
 
  • F. Massimo, A. Beck, A. Specka, I. Zemzemi
    LLR, Palaiseau, France
  • J. Derouillat
    Maison de la Simulation, CEA, Gif-sur-Yvette, France
  • M. Grech, F. Pérez
    LULI, Palaiseau, France
  
  The design of plasma acceleration facilities requires considerable simulation effort for each part of the machine, from the plasma injector and/or accelerator stage(s), to the beam transport stage, from which the accelerated beams will be brought to the users or possibly to another plasma stage. The urgent issues and challenges in simulation of multi-stage acceleration with the Apollon laser of CILEX facility will be addressed. To simulate the beam injection in the second plasma stage, additional physical models have been introduced and tested in the open source Particle in Cell collaborative code Smilei. The efficient initialisation of arbitrary relativistic particle beam distributions through a Python interface allowing code coupling and the self consistent initialisation of their electromagnetic fields will be presented. The comparison between a full PIC simulation and a simulation with a recently developed envelope model, which allows to drastically reduce the computational time, will be also shown for a test case of laser wakefield acceleration of an externally injected electron beam.  
slides icon Slides MOPAG02 [20.462 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-MOPAG02  
About • paper received ※ 15 October 2018       paper accepted ※ 24 October 2018       issue date ※ 26 January 2019  
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TUPAF02 SixTrack Project: Status, Runtime Environment, and New Developments scattering, HOM, collimation, optics 172
 
  • R. De Maria, J. Andersson, L. Field, M. Giovannozzi, P.D. Hermes, N. Hoimyr, G. Iadarola, S. Kostoglou, E.H. Maclean, E. McIntosh, A. Mereghetti, J. Molson, V.K.B. Olsen, D. Pellegrini, T. Persson, M. Schwinzerl, K.N. Sjobak
    CERN, Geneva, Switzerland
  • E.H. Maclean
    University of Malta, Information and Communication Technology, Msida, Malta
  • S. Singh
    Indian Institute of Technology Madras, Chennai, India
  • K.N. Sjobak
    University of Oslo, Oslo, Norway
  • I. Zacharov
    EPFL, Lausanne, Switzerland
  
  Funding: Research supported by the HL-LHC project and Google Summer of Code 2018.
SixTrack is a single-particle tracking code for high-energy circular accelerators routinely used at CERN for the Large Hadron Collider (LHC), its luminosity upgrade (HL-LHC), the Future Circular Collider (FCC), and the Super Proton Synchrotron (SPS) simulations. The code is based on a 6D symplectic tracking engine, which is optimised for long-term tracking simulations and delivers fully reproducible results on several platforms. It also includes multiple scattering engines for beam-matter interaction studies, as well as facilities to run integrated simulations with FLUKA and GEANT4. These features differentiate SixTrack from general-purpose, optics-design software like MAD-X. The code recently underwent a major restructuring to merge advanced features into a single branch, such as multiple ion species, interface with external codes, and high-performance input/output (XRootD, HDF5). This restructuring also removed a large number of build flags, instead enabling/disabling the functionality at run-time. In the process, the code was moved from Fortran 77 to Fortran 2018 standard, also allowing and achieving a better modularization. Physics models (beam-beam effects, RF-multipoles, current carrying wires, solenoid, and electron lenses) and methods (symplecticity check) have also been reviewed and refined to offer more accurate results. The SixDesk runtime environment allows the user to manage the large batches of simulations required for accurate predictions of the dynamic aperture. SixDesk supports CERN LSF and HTCondor batch systems, as well as the BOINC infrastructure in the framework of the LHC@Home volunteering computing project. SixTrackLib is a new library aimed at providing a portable and flexible tracking engine for single- and multi-particle problems using the models and formalism of SixTrack. The tracking routines are implemented in a parametrized C code that is specialised to run vectorized in CPUs and GPUs, by using SIMD intrinsics, OpenCL 1.2, and CUDA tech 		 
slides icon Slides TUPAF02 [0.938 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAF02  
About • paper received ※ 18 October 2018       paper accepted ※ 24 October 2018       issue date ※ 26 January 2019  
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TUPAF06 Simulations of Longitudinal Beam Stabilisation in the CERN SPS With BLonD impedance, emittance, synchrotron, flattop 179
 
  • J. Repond, K. Iliakis, M. Schwarz, E.N. Shaposhnikova
    CERN, Meyrin, Switzerland
  
  The Super Proton Synchrotron (SPS) at CERN, the Large Hadron Collider (LHC) injector, will be pushed to its limits for the production of the High Luminosity LHC proton beam while beam quality and stability in the longitudinal plane are influenced by many effects. Particle simulation codes are an essential tool to study the beam instabilities. BLonD, developed at CERN, is a 2D particle-tracking simulation code, modelling the longitudinal phase space motion of single and multi-bunch beams in multi-harmonic RF systems. Computation of collective effects due to the machine impedance and space charge is done on a multi-turn basis. Various beam and cavity control loops of the RF system are implemented (phase, frequency and synchro-loops, and one-turn delay feedback) as well as RF phase noise injection used for controlled emittance blow-up. The longitudinal beam stability simulations during long SPS acceleration cycle (~ 20 s) include a variety of effects (beam loading, particle losses, controlled blow-up, double RF system operation, low-level RF control, injected bunch distribution, etc.). Simulations for the large number of bunches in the nominal LHC batch (288) use the longitudinal SPS impedance model containing broad and narrow-band resonances between 50 MHz and 4 GHz. This paper presents a study of beam stabilisation in the double harmonic RF system of the SPS system with results substantiated, where possible, by beam measurements.  
slides icon Slides TUPAF06 [1.518 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAF06  
About • paper received ※ 18 October 2018       paper accepted ※ 24 October 2018       issue date ※ 26 January 2019  
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TUPAF08 A Full Field-Map Modeling of Cornell-BNL CBETA 4-Pass Energy Recovery Linac FFAG, linac, optics, dipole 186
 
  • F. Méot, S.J. Brooks, D. Trbojevic, N. Tsoupas
    BNL, Upton, Long Island, New York, USA
  • J.A. Crittenden
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy
The Cornell-BNL Electron Test Accelerator (CBETA) is a four-pass, 150 MeV energy recovery linac (ERL), now in construction at Cornell. A single fixed-field alternating gradient (FFAG) beam line recirculates the four energies, 42, 78, 114 and 150 MeV. The return loop is comprised of 107 quadrupole-doublet cells, built using Halbach permanent magnet technology. Spreader and combiner sections (4 independent beam lines each) connect the 36 MeV linac to the FFAG loop. We present here a start-to-end simulation of the 4-pass ERL, entirely, and exclusively, based on the use of magnetic field maps to model the magnets and correctors. There are paramount reasons for that and this is discussed, detailed outcomes are presented, together with comparisons with regular beam transport (mapping based) techniques. 		 
slides icon Slides TUPAF08 [2.568 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAF08  
About • paper received ※ 23 October 2018       paper accepted ※ 07 December 2018       issue date ※ 26 January 2019  
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TUPAF10 Experience With CBETA Online Modeling Tools EPICS, lattice, linac, MMI 196
 
  • C.M. Gulliford, A.C. Bartnik, J. Dobbins, D. Sagan
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • J.S. Berg
    BNL, Upton, Long Island, New York, USA
  • A. Nunez-delPrado
    UCF, Orlando, USA
  
  Funding: NYSERDA, the New York StateEnergy Research and Development Agency
The Cornell-Brookhaven CBETA machine is a four pass Energy Recovery Linac (ERL) with a Non-scaling Fixed-Field Alternating gradient (NS-FFA) arc. For online modeling of single particle dynamics in CBETA, a customized version of the Tao program, which is based upon the Bmad toolkit, has been developed. This online program, called CBETA-V, is interfaced to CBETA’s EPICS control system. This paper describes the online modeling system and initial experience during machine running. 		 
slides icon Slides TUPAF10 [4.227 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAF10  
About • paper received ※ 17 October 2018       paper accepted ※ 28 January 2019       issue date ※ 26 January 2019  
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TUPAF12 Longitudinal Beam Dynamics With a Higher-Harmonic Cavity for Bunch Lengthening cavity, operation, storage-ring, synchrotron 202
 
  • G. Bassi, J. Tagger
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy
We discuss the longitudinal beam dynamics in storage rings in the presence of a higher-harmonic cavity (HHC) system for bunch lengthening. We first review the general conditions for HHC operations, either in active or passive mode, assuming the stability of the system. For uniform filling patterns, a distinction is made between operations with a normal-conducting HHC, where optimal conditions for bunch lengthening can be satisfied, and operations with super-conducting HHC, where optimal conditions can be met only approximately. The option to operate the NSLS-II storage ring with a passive, super-conducting third harmonic cavity (3HC) system is discussed next. The stability and performance of the system in the presence of a gap in the uniform filling, which corresponds to the present mode of operation of the NSLS-II storage ring, is investigated with self-consistent Vlasov-Fokker-Planck simulations performed with the code SPACE*.
* G. Bassi, A. Blednykh and V. Smaluk, Phys Rev. Accel. Beams 19, 024401 (2016). 		 
slides icon Slides TUPAF12 [17.562 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAF12  
About • paper received ※ 20 October 2018       paper accepted ※ 28 January 2019       issue date ※ 26 January 2019  
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TUPAF15 A Holistic Approach to Simulating Beam Losses in the Large Hadron Collider Using BDSIM collimation, quadrupole, beam-losses, ECR 221
 
  • S.D. Walker, A. Abramov, S.T. Boogert, H. Garcia Morales, S.M. Gibson, L.J. Nevay, H. Pikhartova, W. Shields
    JAI, Egham, Surrey, United Kingdom
  
  To fully understand the beam losses, subsequent radiation, energy deposition, backgrounds and activation in particle accelerators, a holistic approach combining a 3-D model, physics processes and accelerator tracking is required. Beam Delivery Simulation (BDSIM) is a program developed to simulate the passage of particles, both primary and secondary, in particle accelerators and calculate the energy deposited by these particles via material interactions using the Geant4 physics library. A Geant4 accelerator model is built from an existing optical description of a lattice by procedurally placing a set of predefined accelerator components. These generic components can be refined to an arbitrary degree of detail with the use of user-defined geometries, detectors, field maps, and more. A detailed model of the Large Hadron Collider has been created in BDSIM, validated with existing tracking codes and applied to study beam loss patterns.  
slides icon Slides TUPAF15 [2.065 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAF15  
About • paper received ※ 31 October 2018       paper accepted ※ 08 December 2018       issue date ※ 26 January 2019  
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TUPAF19 pyaopt Optimization Suite and its Applications to an SRF Cavity Design for UEMs SRF, gun, cavity, electron 229
 
  • A. Liu, P.V. Avrakhov, R.A. Kostin
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • C.-J. Jing
    Euclid Beamlabs LLC, Bolingbrook, USA
  
  Funding: DOE SBIR
In order to achieve sharp, high resolution real-time imaging, electrons in a MeV UEM (ultrafast electron microscope) beamline need to minimize instabilities. The Superconducting RF (SRF) photocathode gun is a promising candidate to produce highly stable electrons for UEM/UED applications. It operates in an ultrahigh Q, CW mode, and dissipates a few watts of RF power, which make it possible to achieve a 10s ppm level of beam stability by using modern RF control techniques. In order to find the best performance of the gun design, an optimization procedure is required. pyaopt is a Python-based optimization suite that supports multi-objective optimizations using advanced algorithms. In this paper, the novel SRF photogun design and its optimizations through pyaopt and Astra’s beam simulations will be discussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAF19  
About • paper received ※ 22 October 2018       paper accepted ※ 15 December 2018       issue date ※ 26 January 2019  
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TUPAF20 Mean-Field Density Evolution of Bunched Particles With Non-Zero Initial Velocity electron, emittance, distributed, space-charge 233
 
  • B.S. Zerbe, P.M. Duxbury
    MSU, East Lansing, Michigan, USA
  
  Funding: NSF Grant 1625181 NSF Grant RC108666 MSU Col. Nat. Sci., Provost Off., Col. Comm. Art and Sci.
Reed (2006) presented a 1D mean-field model of initially cold pancake-beam expansion demonstrating that the evolution of the entire spatial distribution can be solved for all time where the 1D assumption holds. This model is relevant to ultra-fast electron microscopy as it describes the evolution of the distribution within the photoelectron gun, and this model is similar to Anderson’s sheet beam density time dependence (Anderson 1987) except that Reed’s theory applies to freely expanding beams instead of beams within a focussing channel. Our recent work (Zerbe 2018) generalized Reed’s analysis to cylindrical and spherical geometries demonstrating the presence of a shock that is seen in the Coulomb explosion literature under these geometries and further discussed the absence of a shock in the 1D model. This work is relevant as it offers a mechanistic explanation of the ring-like density shock that arises in non-equilibrium pancake-beams within the photoelectron gun; moreover, this shock is coincident with a region of high-temperature electrons providing an explanation for why experimentally aperturing the electron bunch results in a greater than 10-fold improvement in beam emittance(Williams 2017), possibly even resulting in bunch emittance below the intrinsic emittance of the cathode. However, this theory has been developed for cold-bunches, i.e. bunches of electrons with 0 initial momentum. Here, we briefly review this new theory and extend the cylindrical- and spherical- symmetric distribution to ensembles that have non-zero initial momentum distributions that are symmetric but otherwise unrestricted demonstrating how initial velocity distributions couple to the shocks seen in the less general formulation. Further, we derive and demonstrate how the laminar condition may be propagated through beam foci. 		 
slides icon Slides TUPAF20 [1.396 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAF20  
About • paper received ※ 19 October 2018       paper accepted ※ 15 December 2018       issue date ※ 26 January 2019  
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TUPAF22 FEL Simulation Using the Lie Method wiggler, FEL, bunching, electron 240
 
  • K. Hwang, J. Qiang
    LBNL, Berkeley, California, USA
  
  Funding: U.S. Department of Energy under Contract No. DE-AC02-05CH11231
Advances in numerical methods for free-electron-laser~(FEL) simulation under wiggler period averaging~(WPA) are presented. First, WPA is generalized using perturbation Lie map method. The conventional WPA is identified as the leading order contribution. Next, a widely used shot-noise modeling method is improved along with a particle migration scheme across the numerical mesh. The artificial shot noise arising from particle migration is suppressed. The improved model also allows using arbitrary mesh size, slippage resolution, and integration step size. These advances will improve modeling of longitudinal beam profile evolution for fast FEL simulation. 		 
slides icon Slides TUPAF22 [2.245 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAF22  
About • paper received ※ 17 October 2018       paper accepted ※ 28 January 2019       issue date ※ 26 January 2019  
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TUPAF23 Start-to-End Simulations of THz SASE FEL Proof-of-Principle Experiment at PITZ undulator, electron, FEL, emittance 246
 
  • M. Krasilnikov, P. Boonpornprasert, F. Stephan
    DESY Zeuthen, Zeuthen, Germany
  • H.-D. Nuhn
    SLAC, Menlo Park, California, USA
  • E. Schneidmiller, M.V. Yurkov
    DESY, Hamburg, Germany
  
  The Photo Injector Test facility at DESY in Zeuthen (PITZ) develops high brightness electron sources for modern linac-based Free Electron Lasers (FELs). The PITZ accelerator has been proposed as a prototype for a tunable, high power THz source for pump and probe experiments at the European XFEL. A Self-Amplified Spontaneous Emission (SASE) FEL is considered to generate the THz pulses. High radiation power can be achieved by utilizing high charge (4 nC) shaped electron bunches from the PITZ photo injector. THz pulse energy of up to several mJ is expected from preliminary simulations for 100 um radiation wavelength. For the proof-of-principle experiments a re-usage of LCLS-I undulators at the end of the PITZ beamline is under studies. One of the challenges for this setup is transport and matching of the space charge dominated electron beam through the narrow vacuum chamber. Start-to-end simulations for the entire experimental setup - from the photocathode to the SASE THz generation in the undulator section - have been performed by combination of several codes: ASTRA, SC and GENESIS-1.3. The space charge effect and its impact onto the output THz radiation have been studied. The results of these simulations will be presented and discussed.  
slides icon Slides TUPAF23 [2.534 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAF23  
About • paper received ※ 18 October 2018       paper accepted ※ 24 October 2018       issue date ※ 26 January 2019  
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TUPAG02 First Steps Towards a New Finite Element Solver for MOEVE PIC Tracking electron, FEM, emittance, vacuum 260
 
  • U. van Rienen, C.R. Bahls, J. Heller, D. Zheng
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • U. van Rienen
    University of Rostock, Rostock, Germany
  
  Funding: This work has been supported by the German Federal Ministry for Research and Education BMBF under contract 015K16HRA.
A relevant task in designing high-brilliance light sources based on high-current linear accelerators (e.g. Energy Recovery Linacs (ERLs)) consists in systematic investigations of ion dynamics in the vacuum chamber of such machines. This is of high importance since the parasitic ions generated by the electron beam turned out to be a current-limiting factor for many synchrotron radiation sources. In particular, the planned high current operation at ERL facilities requires a precise analysis and an accurate development of appropriate measures for the suppression of ion-induced beam instabilities. The longitudinal transport of ions through the whole accelerator plays a key role for the establishment of the ion concentration in the machine. Using the Particle-in-Cell (PIC) method, we started redesigning our code MOEVE PIC Tracking in order to allow for the fast estimation of the effects of ions on the beam dynamics. For that, we exchanged the previously used Finite Difference (FD) method for the solution of Poisson’s equation within the PIC solver by a solver based on the Finite Element Method (FEM). Employing higher order FEM, we expect to gain improved convergence rates and thus lower computational times. We chose the Open Source Framework FEniCS for our new implementation. 		 
slides icon Slides TUPAG02 [0.924 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAG02  
About • paper received ※ 21 October 2018       paper accepted ※ 24 October 2018       issue date ※ 26 January 2019  
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TUPAG10 Nonlinear Optics at UMER: Lessons Learned in Simulation octupole, lattice, optics, resonance 278
 
  • K.J. Ruisard, B.L. Beaudoin, I. Haber, T.W. Koeth, D.B. Matthew
    UMD, College Park, Maryland, USA
  
  Funding: Funding through DOEHEP Award DESC0010301, NSF Award PHY1414681, NSF GRFP program. Manuscript authored by UT-Battelle, LLC, under Contract No. DEAC0500OR22725 with the U.S. Department of Energy.
Invited talk: Design of accelerator lattices with nonlinear optics to suppress transverse resonances is a novel approach and may be crucial for enabling low-loss high-intensity beam transport. Large amplitude-dependent tune spreads, driven by nonlinear field inserts, damp resonant response to driving terms. This presentation will focus on simulations of the UMER lattice operated as a quasi-integrable system (1 invariant of transverse motion) with a single strong octupole insert. We will discuss the evolution of simulation models, including the observation of losses associated with the original operating point near a fourth-order resonance. Other operating points farther from this resonance are considered and shown to be more promising. 		 
slides icon Slides TUPAG10 [3.447 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAG10  
About • paper received ※ 19 October 2018       paper accepted ※ 28 January 2019       issue date ※ 26 January 2019  
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TUPAG11 ESS Accelerator Lattice Design Studies and Automatic Synoptic Deployment rfq, lattice, ion-source, controls 285
 
  • Y. Levinsen, R. De Prisco, M. Eshraqi, T.J. Grandsaert, A. Jansson, H. Kocevar, Ø. Midttun, N. Milas, R. Miyamoto, D.C. Plostinar, A. Ponton, T.J. Shea
    ESS, Lund, Sweden
  • H.D. Thomsen
    AU, Aarhus, Denmark
  
  The European Spallation Source (ESS) is currently under construction in the south of Sweden. A highly brilliant neutron source with a 5 MW proton driver will provide state of the art experimental facilities for neutron science. A peak proton beam power in the accelerator of 125 MW means that excellent control over the beam losses becomes essential. The beam physics design of the ESS accelerator is in a TraceWin format, for which we have developed revision control setup, automated regression analysis and deployment of synoptic viewer and tabulated spreadsheets. This allows for an integrated representation of the data that are always kept synchronized and available to other engineering disciplines. The design of the accelerator lattice has gone through several major and minor iterations which are all carefully analysed. In this contribution we present the status of the latest studies which is the first time a complete end-to-end study beginning from the ion source has been performed.  
slides icon Slides TUPAG11 [7.733 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAG11  
About • paper received ※ 18 October 2018       paper accepted ※ 28 January 2019       issue date ※ 26 January 2019  
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TUPAG13 S-Based Macro-Particle Spectral Algorithm for an Electron Gun electron, cathode, gun, solenoid 290
 
  • P. M. Jung, T. Planche
    TRIUMF, Vancouver, Canada
  
  We derive a Hamiltonian description of a continuous particle distribution and its electrostatic potential from the Low Lagrangian. The self consistent space charge potential is discretized according to the spectral Galerkin approximation. The particle distribution is discretized using macro-particles. We choose a set of initial and boundary conditions to model the TRIUMF 300keV thermionic DC electron gun. The field modes and macro-particle coordinates are integrated self-consistently. The current status of the implementation is discussed.  
slides icon Slides TUPAG13 [1.335 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAG13  
About • paper received ※ 01 November 2018       paper accepted ※ 10 December 2018       issue date ※ 26 January 2019  
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TUPAG20 Computational Beam Dynamics Requirements for FRIB linac, ECR, emittance, controls 303
 
  • P.N. Ostroumov, Y. Hao, T. Maruta, A.S. Plastun, T. Yoshimoto, T. Zhang, Q. Zhao
    FRIB, East Lansing, USA
  
  Funding: Work supported by the U.S. DOE of Science under Cooperative Agreement DE-SC0000661 and the NSF under Cooperative Agreement PHY-1102511, the State of Michigan and Michigan State University.
The Facility for Rare Isotope Beams (FRIB) being built at Michigan State University moved to the commissioned stage in the summer of 2017. There were extensive beam dynamics simulations in the FRIB driver linac during the design stage. Recently, we have used TRACK and IMPACT simulation codes to study dynamics of ion beam contaminants extracted from the ECR together with main ion beam. The contaminant ion species can produce significant losses after the stripping. These studies resulted in development of beam collimation system at relatively low energy of 16 MeV/u and room temperature bunchers instead of originally planned SC cavities. Commissioning of the Front End and the first 3 cryomodules enabled detailed beam dynamics studies experimentally which were accompanied with the simulations using above-mentioned beam dynamics codes and optimization code FLAME. There are significant challenges in understanding of beam dynamics in the FRIB linac. The most computational challenges are in the following areas: (1) Simulation of the ion beam formation and extraction from the ECR; (2) Development of the virtual accelerator model available on-line both for optimization and multi-particle simulations. The virtual model should include realistic accelerator parameters including device misalignments; (3) Large scale simulations to support high-power ramp up of the linac with minimized beam losses; (4) Interaction of the beam with the gas stripper which is the backup option for high power operation of the linac. 		 
slides icon Slides TUPAG20 [5.721 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAG20  
About • paper received ※ 02 November 2018       paper accepted ※ 10 December 2018       issue date ※ 26 January 2019  
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TUPAG21 Novel, Fast, Open-Source Code for Synchrotron Radiation Computation on Arbitrary 3D Geometries GPU, undulator, radiation, electron 309
 
  • D.A. Hidas
    BNL, Upton, Long Island, New York, USA
  
  Open Source Code for Advanced Radiation Simulation (OSCARS) is an open-source project (https://oscars.bnl.gov) developed at Brookhaven National Laboratory for the computation of synchrotron radiation from arbitrary charged particle beams in arbitrary and time-dependent mag- netic and electric fields on arbitrary geometries in 3D. Computational speed is significantly increased with the use of built-in multi-GPU and multi-threaded techniques which are suitable for both small scale and large scale computing infrastructures. OSCARS is capable of computing spectra, flux, and power densities on simple surfaces as well as on objects imported from common CAD software. It is additionally applicable in the regime of high-field acceleration. The methodology behind OSCARS cal- culations will be discussed along with practical examples and applications to modern accelerators and light sources.  
slides icon Slides TUPAG21 [1.712 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAG21  
About • paper received ※ 20 October 2018       paper accepted ※ 18 December 2018       issue date ※ 26 January 2019  
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WEPAF01 A Compact Permanent Magnet Spectrometer for CILEX electron, dipole, laser, permanent-magnet 320
 
  • M. Khojoyan, A. Cauchois, J. Prudent, A. Specka
    LLR, Palaiseau, France
  
  Laser Wakefield acceleration experiments make exten- sive use of small permanent magnets or magnet assemblies for analyzing and focusing electron beams produced in plasma accelerators. Besides being compact, these magnets have to have a large angular acceptance for the divergent laser and electron beams which imposes constraint of the gap size. We will present the optimized design and charac- terization of a 100 mm long, 2.1 Tesla permanent magnet dipole. Furthermore, we will present the performance of such a magnet as a spectrometer in the CILEX/APOLLON 10PW laser facility in France.  
slides icon Slides WEPAF01 [6.898 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-WEPAF01  
About • paper received ※ 15 October 2018       paper accepted ※ 28 January 2019       issue date ※ 26 January 2019  
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WEPAF02 Simulations of Beam Chopping for Potential Upgrades of the SNS LEBT Chopper rfq, LEBT, gun, operation 325
 
  • B. Han, S.N. Murray, T.R. Pennisi, V.V. Peplov, M.P. Stockli, R.F. Welton
    ORNL, Oak Ridge, Tennessee, USA
  • R.B. Saethre, C. Stinson
    ORNL RAD, Oak Ridge, Tennessee, USA
  
  Funding: This work was performed at Oak Ridge National Laboratory, which is managed by UT-Battelle, LLC, under contract number DE-AC05-00OR22725 for the United States Department of Energy.
The LEBT chopper is a critical element of the SNS accelerator system. In this work, the benefit of increasing the chopping voltage amplitude for the present chopping pattern is shown with beam simulations, and an ongoing hardware upgrade of the chopper pulser units is discussed. In addition, with the prospect of higher voltage capability of the new pulser design, two alternative chopping patterns which reduce the switching frequency of the chopper pulsers down to 1/2 or 1/4 of the present chopping pattern, are also explored with beam simulations. 		 
slides icon Slides WEPAF02 [7.431 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-WEPAF02  
About • paper received ※ 31 October 2018       paper accepted ※ 07 December 2018       issue date ※ 26 January 2019  
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WEPAF04 Longitudinal Beam Dynamics in FRIB and ReA Linacs rfq, cavity, emittance, linac 330
 
  • A.S. Plastun, P.N. Ostroumov, A.C.C. Villari, Q. Zhao
    FRIB, East Lansing, USA
  
  The Front-End and first three cryomodules of the Facility for Rare Isotope Beam (FRIB) at Michigan State University (MSU) commissioned in July, 2018. The paper describes the online tuning procedures of the longitudinal beam dynamics through the FRIB linac. These procedures include tuning of the accelerating field phases and amplitudes in the cavities. We developed an automated simulation-based tuning procedure for the multi-harmonic buncher. In order to tune the radio-frequency quadrupole (RFQ) we measured and calculated its threshold voltage and scanned its longitudinal acceptance. Tuning of the rebunchers and superconducting accelerating cavities is per-formed by means of the phase scans and Time-Of-Flight (TOF) beam energy measurements with beam position and phase monitors. While FRIB is being commissioned, the re-accelerator (ReA3) for rare isotope beams (RIBs) is being upgraded. We redesigned the ReA3 RFQ to improve its cooling system and provide reliable operation with 16.1 MHz prebunched ion beams with A/Q = 5. In order to provide matching of any ReA3 beam both to the following upgrade cryomodules and physics experiments’ requirements, room temperature rebuncher/debuncher is being designed. The design procedure includes the beam dynamics, electromagnetic, thermal and mechanical simulations and optimizations.  
slides icon Slides WEPAF04 [2.406 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-WEPAF04  
About • paper received ※ 19 October 2018       paper accepted ※ 28 January 2019       issue date ※ 26 January 2019  
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WEPLG01 Analysis of Emittance Growth in a Gridless Spectral Poisson Solver for Fully Symplectic Multiparticle Tracking emittance, space-charge, lattice, plasma 335
 
  • C.E. Mitchell, J. Qiang
    LBNL, Berkeley, California, USA
  
  Funding: This work was supported by the Director, Office of Science, Office of High Energy Physics, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Gridless spectral methods for self-consistent symplectic space charge modeling possess several advantages over traditional momentum-conserving particle-in-cell methods, including the absence of numerical grid heating and the presence of an underlying multi-particle Hamiltonian. Nevertheless, evidence of collisional particle noise remains. For a class of such 1D and 2D algorithms, we provide analytical models of the numerical field error, the optimal choice of spectral modes, and the numerical emittance growth per timestep. We compare these results with the emittance growth models of Struckmeier, Hoffman, Kesting, and others. 		 
slides icon Slides WEPLG01 [11.804 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-WEPLG01  
About • paper received ※ 18 October 2018       paper accepted ※ 28 January 2019       issue date ※ 26 January 2019  
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WEPLG03 Theoretical and Computational Modeling of a Plasma Wakefield BBU Instability plasma, wakefield, impedance, dipole 341
 
  • S.D. Webb, D.L. Bruhwiler, N.M. Cook
    RadiaSoft LLC, Boulder, Colorado, USA
  • A.V. Burov, V.A. Lebedev, S. Nagaitsev
    Fermilab, Batavia, Illinois, USA
  
  Funding: This work was supported in part by the Department of Energy, Office of Science, Office of High Energy Physics, under contract number DE-SC0018718.
Plasma wakefield accelerators achieve accelerating gradients on the order of the wave-breaking limit, m c2 kp/e, so that higher accelerating gradients correspond to shorter plasma wavelengths. Small-scale accelerating structures, such as plasma and dielectric wakefields, are susceptible to the beam break-up instability (BBU), which can be understood from the Panofsky-Wenzel theorem: if the fundamental accelerating mode scales as b-1 for a structure radius b, then the dipole mode must scale as b-3, meaning that high accelerating gradients necessarily come with strong dipole wake fields. Because of this relationship, any plasma-accelerator-based future collider will require detailed study of the trade-offs between extracting the maximum energy from the driver and mitigating the beam break-up instability. Recent theoretical work* predicts the tradeoff between the witness bunch stability and the amount of energy that can be extracted from the drive bunch, a so-called efficiency-instability relation . We will discuss the beam break-up instability and the efficiency-instability relation and the theoretical assumptions made in reaching this conclusion. We will also present preliminary particle-in-cell simulations of a beam-driven plasma wakefield accelerator used to test the domain of validity for the assumptions made in this model.
* V. Lebedev, A. Burov, and S. Nagaitsev, "Efficiency versus
instability in plasma accelerators", Phys. Rev. Acc. Beams 20, 121301
(2017). 		 
slides icon Slides WEPLG03 [2.234 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-WEPLG03  
About • paper received ※ 01 November 2018       paper accepted ※ 28 January 2019       issue date ※ 26 January 2019  
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WEPLG05 Review of Spectral Maxwell Solvers for Electromagnetic Particle-in-Cell: Algorithms and Advantages plasma, laser, electron, distributed 345
 
  • R. Lehé, J.-L. Vay
    LBNL, Berkeley, California, USA
  
  Electromagnetic Particle-In-Cell codes have been used to simulate both radio-frequency accelerators and plasma-based accelerators. In this context, the Particle-In-Cell algorithm often uses the finite-difference method in order to solve the Maxwell equations. However, while this method is simple to implement and scales well to multiple processors, it is liable to a number of numerical artifacts that can be particularly serious for simulations of accelerators. An alternative to the finite-difference method is the use of spectral solvers, which are typically less prone to numerical artifacts. In this talk, I will review recent progress in the use of spectral solvers for simulations of plasma-based accelerators. This includes techniques to scale those solvers to large number of processors, extensions to cylindrical geometry, and adaptations to specific problems such as boosted-frame simulations.  
slides icon Slides WEPLG05 [2.861 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-WEPLG05  
About • paper received ※ 06 November 2018       paper accepted ※ 28 January 2019       issue date ※ 26 January 2019  
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