05 Beam Dynamics and EM Fields
D11 Code Developments and Simulation Techniques
Paper Title Page
TUPMF016 Application of SVD Analysis to Deflecting Cavitiy Space Harmonics 1283
  • C. Yao, L. Emery, D. Hui, H. Shang, Y.P. Sun
    ANL, Argonne, Illinois, USA
  Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Singular value decomposition (SVD) analysis is a powerful tool for identifying different spatial and timing variation patterns in many fields of researches. Recently we applied complex SVD method to space harmonic analysis of a 13-cell defecting cavity that is built and installed in the APS linac injector for beam phase space characterization and emittance exchange experiments. Real and imaginary space harmonics components are extracted from CST simulated data. Fields inside the iris were expressed in analytic forms and produced good agreement. Work is underway to implement the results into elegant simulation model.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF016  
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THPAF016 3D Tracking Methods in a GEANT4 Environment Through Electrostatic Beamlines 2979
  • J.R. Hunt, J. Resta-López, V. Rodin, B. Veglia, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • J.R. Hunt, J. Resta-López, V. Rodin, B. Veglia, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  Funding: Work supported by the EU under Grant Agreement 721559 and the STFC Cockcroft Institute core Grant No. ST/G008248/1.
Due to the relatively infrequent use of electrostatic beamline elements compared with their magnetic counterparts, there are few particle tracking codes which allow for the straightforward implementation of such beamlines. In this contribution, we present 3D tracking methods for beamlines containing electrostatic elements utilising a modified version of the Geant4 based tracking code 'G4beamline'. In 2020 transfer lines will begin transporting extremely low energy (100 keV) antiproton beams from the Extra Low Energy Antiproton (ELENA) ring to the antimatter experiments at CERN. Electrostatic bending and focusing elements have been chosen for the beamlines due to their mass independence and focusing efficiency in the low energy regime. These beamlines form the basis of our model which is benchmarked against simplified tracking simulations. Realistic beam distributions obtained via tracking around ELENA in the presence of collective effects and electron cooling will be propagated along the optimised 3D transfer model to achieve the best beam quality possible for the experiments.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF016  
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THPAF017 Improvement of RF Field Phase and Amplitude Errors Simulations in TraceWin Code 2983
  • D. Uriot
    IRFU, CEA, University Paris-Saclay, Gif-sur-Yvette, France
  Funding: This work is supported by the European Atomic Energy Community's (EURATOM) H2020 Programme under grant agreement n°662186 (MYRTE project)
RF field phase and amplitude errors are usually not correctly simulated and it is a serious problem especially when in high intensity linear accelerators, the main losses are due to particle leaving the beam acceptance. This new development implemented in TraceWin fixes this issue. The objective is to improve the longitudinal beam dynamics simulation methods, by including more close-to-real models for the cavities tuning procedure. By this way, clear distinction should be done between static and dynamic errors and longitudinal diagnostics accuracy can be clearly defined according to beam dynamics results.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF017  
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THPAF028 Multi-Objectives Genetic Algorithms (MOGA) Optimization of PETRA IV Scenarios 3015
  • X.N. Gavaldà, J. Keil, R. Wanzenberg
    DESY, Hamburg, Germany
  This paper reports the application of Multi-Objective Genetic Algorithms (MOGA) to optimize the linear and nonlinear beam dynamics of the different PETRA IV scenarios to transform PETRA III storage ring in a diffracted limited one. As it is well known, the dynamic aperture and momentum acceptance of these kinds of lattices are dramatically reduced due to the increase of the sextupoles strengths to compensate its strong focusing. The reduction of the dynamic aperture jeopardizes the current off-axis injection system and lower beam lifetimes increase the beam instabilities and the radiation safety concerns of the storage ring. MOGA searches the best settings of quadrupoles and sextupoles in a multi-dimensional parameter space taking into account the dynamic properties and the natural emittance as objectives at the level of ten picometers. The lattices studied are the so-called 'Twist lattice' based in a phase space exchange lattice, a solution based in the ESRF-Hybrid Multi-bend Achromat (HMA) design and finally the 'double 'I' lattice combining a non-interleaved sextupoles cell with an ESRF-HMA cell.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF028  
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THPAF030 PETRA III Storage Ring Performance Improvement Based on Multi-Objective Genetic Algorithms (MOGA) 3018
  • X.N. Gavaldà, J. Keil, G.K. Sahoo, R. Wanzenberg
    DESY, Hamburg, Germany
  The performance of the 3th generation light sources relies on the beam lifetime and the injection efficiency, both related with the beam dynamic properties of the storage ring as momentum acceptance and dynamic aperture, respectively. High values of beam lifetime and injection efficiency are desirable to reduce the storage ring instabilities during injection, the radiation losses and the energy consumption of the facility. This paper reports the first application of Multi-Objective Genetic Algorithms (MOGA) to optimize the linear and non-linear beam dynamics of PETRA III storage ring. Genetic algorithms are a heuristic search that mimics the process of natural evolution to optimize problems with a high level of complexity, as in the case of PETRA III storage ring composed by hundreds of magnets. This computational method uses hundreds of CPUs. MOGA is used to maximize the dynamic aperture and the momentum acceptance finding new combinations of quadrupole and sextupole settings in a multi-dimensional parameter space maintaining the solutions in the level of ten picometers.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF030  
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THPAF059 Ultra Compact Symplectic Scheme for Fast Multi-Particle Tracking 3107
  • K. Skoufaris, Y. Papaphilippou, D. Pellegrini
    CERN, Geneva, Switzerland
  A versatile symplectic integration scheme has been developed in order to produce simplified versions of non linear lattices, preserving fundamental non-linear properties such as the detuning with amplitude and energy, in addition to the linear transport. The method has been applied to the LHC and benchmarked against tracking simulations with Sixtrack. This reduced lattice is made available as a refined replacement of the simple rotation matrix often used in multi-particle studies requiring a fast beam transport routine.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF059  
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THPAF064 Beam Dynamics with Covariant Hamiltonians 3123
  • B.T. Folsom, E. Laface
    ESS, Lund, Sweden
  We demonstrate covariant beam-physics simulation through multipole magnets using Hamiltonians relying on canonical momentum. Space-charge integration using the Lienard–Wiechert potentials is also discussed. This method is compared with conventional nonlinear Lie-operator tracking and the TraceWin software package.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF064  
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THPAF076 Using Graphic-Turtle with the Particle Beam Optics Laboratory (PBO Lab) 3158
  • G.H. Gillespie
    G.H. Gillespie Associates, Inc., Del Mar, California, USA
  A Particle Beam Optics Laboratory (PBO Lab) module has been developed for the Paul Scherrer Institute (PSI) version of the TURTLE program commonly known as Graphic-Turtle. The PSI-TURTLE version extends the original TURTLE program by including several unique beam optics capabilities, as well as by providing a self-contained graphics package. The unique optics modeling, together with the data visualization enhancements, make the PSI-TURTLE program ideal for certain types of beam simulations. The PBO Lab environment provides a single graphic user interface (GUI) that features an easy-to-learn and easy-to-use drag-and-drop beamline construction kit. Underlying the GUI is a sophisticated object model developed specifically for the accelerator community. PBO Lab provides a common interface for multiple charged particle optics codes. Modules have been developed for a number of popular beam optics programs that cover a range of accelerator types and applications. The PSI-TURTLE Module extends those capabilities. The module is described and its main capabilities and limitations are summarized.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF076  
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THPAF083 LINAC-Multitool - an Open Source Java-Toolkit 3179
  • M. Schwarz, D. Bade, J. Corbet, H. Podlech
    IAP, Frankfurt am Main, Germany
  Funding: Work supported by BMBF contr. No. 05P15RFRBA and HIC for FAIR.
Dedicating more precious time to advanced research instead of spending it towards time-consuming routine tasks is a desirable goal in particle accelerator simulation and development. Requirements engineering was started at IAP in order to identify routine processes at our institute's R&D that can be automated or simplified. Results indicated that there were several areas to consider: Bead pull measurements, data processing and visualization for the beam dynamics code LORASR, CST field map processing for the use with TraceWin, conversion between different particle distribution data formats and more. Subsequently development of the LINAC-Multitool started to rationalize these processes and replace preexisting scripts also to ensure consistency of results and increase transparency and reliability of computation. In order to guarantee maintainability, expandability and platform independence, LINAC-Multitool is programmed using Java and will be open source. This contribution presents the current state of development.
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THPAF085 Estimation of Dielectric Losses in the Bessy VSR Warm Beam Pipe Absorbers 3185
  • T. Flisgen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • H.-W. Glock
    HZB, Berlin, Germany
  • A.V. Tsakanian
    Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany
  Funding: Work supported by the German Bundesministerium für Bildung und Forschung, Land Berlin and grants of Helmholtz Association.
Currently Helmholtz Zentrum Berlin prepares the update of the BESSY II ring to BESSY VSR. The updated ring will be capable to simultaneously store short and long bunches to satisfy the various user demands. For this sake, a cryomodule accommodating two 1.5 GHz and two 1.75 GHz superconducting cavities will be installed into the storage ring. The cavity string will be equipped with warm dielectric absorber rings at both ends. Together with the waveguide dampers of the cavities, these rings damp electromagnetic fields excited by the beam. This contribution presents the estimation of the dielectric losses in the beam pipe absorber rings of the BESSY VSR module. The presented approach is based on determining a broad band impedance of the dielectric ring by exciting the numerical model with a single broad band Gaussian bunch. Subsequently, the power deposited into the ring is estimated in frequency domain by multiplying the impedance with the square of the beam current for all considered harmonics of the beam. Finally, these power contributions are added up. In addition to details of the scheme, the contribution presents results for the recent absorber layout of the BESSY VSR string.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF085  
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THPAK009 Benchmark Analyses of Electrostatic Devices for SPIRAL2-DESIR Beam Lines 3225
  • L. Perrot, M. Kemel, S. Rousselot
    IPN, Orsay, France
  Funding: French ANR, Investissements d'Avenir, EQUIPEX. Contract number ANR-11-EQPX-0012.
The new ISOL facility SPIRAL2 is currently being built at GANIL, Caen France. The commissioning of the accelerator is in progress since 2015. SPIRAL2 will produce a large number of new radioactive ion beams (RIB) at high intensities. In 2023, the DESIR facility will receive beams from the upgraded SPIRAL1 facility of GANIL (stable beam and target fragmentation), from the S3 Low Energy Branch (fusion-evaporation and deep-inelastic reactions). In order to deliver the RIB to the experimental set-ups installed in the DESIR hall, 140 meters of beam line are studied since 2014. The transfert lines are today fully design and building will start in 2018. Electrostatic devices (quadrupoles, steerers and deflectors) have been intensively study using various tools. This paper will focus on the detail results of a benchmark using OPERA3D and Comsol Multiphysics apply to the DESIR quadrupole conception.
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THPAK018 Recent Developments in DEMIRCI for RFQ Design 3243
  • E. Celebi
    IBU, Istanbul, Turkey
  • O. Cakir, G. Turemen
    Ankara University, Faculty of Sciences, Ankara, Turkey
  • G. Turemen
    TAEK, Ankara, Turkey
  • G. Unel
    UCI, Irvine, California, USA
  Funding: This project has been supported by TUBITAK with project number 114F106 and 117F143.
DEMIRCI software aims to aid RFQ design efforts by making the process easy, fast and accurate. In this report, DEMIRCI 8-term potential results are compared with the results provided by other commercially available simulation software. Computed electric fields are compared to the re- sults from simulations of a recently produced 352 MHz RFQ. Recent developments like the inclusion of space charge ef- fects in DEMIRCI beam dynamics are also discussed. More- over, further terms are added to 8-term potential to simulate possible vane production errors. The FEM solver was also improved to mesh the cells with errors.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK018  
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THPAK025 Recent Developments in Beam Delivery Simulation - BDSIM 3266
  • L.J. Nevay, A. Abramov, S.T. Boogert, H. Garcia Morales, S.M. Gibson, W. Shields, S.D. Walker
    JAI, Egham, Surrey, United Kingdom
  • J. Snuverink
    PSI, Villigen PSI, Switzerland
  Funding: Work supported by Science and Technology Research council grant 'The John Adams Institute for Accelerator Science' ST/P00203X/1 and Impact Acceleration Account.
Beam Delivery Simulation (BDSIM) is a program to seamlessly simulate the passage of particles in an accelerator, the surrounding environment and detectors. It uses a suite of high energy physics software including Geant4, CLHEP and ROOT to create a 3D model from an optical description of an accelerator and simulate the interaction of particles with matter as well as the production of secondaries. BDSIM is used to simulate energy deposition and charged particle backgrounds in a variety of accelerators worldwide. The latest developments are presented including low-energy tracking extension, more detailed geometry, support for ion beams and improved magnetic fields. A new analysis suite that allows scalable event by event analysis is described for advanced analysis such as the trace back of energy deposition to primary particle impacts.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK025  
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THPAK030 Studies of Longitudinal Dynamics in the Micro-Bunching Instability Using Machine Learning 3277
  • T. Boltz, M. Brosi, E. Bründermann, A.-S. Müller, P. Schönfeldt, M. Yan
    KIT, Karlsruhe, Germany
  • M. Schwarz
    CERN, Geneva, Switzerland
  The operation of synchrotron light sources with short electron bunches increases the emitted CSR power in the THz frequency range. However, the spatial compression leads to complex longitudinal dynamics, causing the formation of micro-structures in the longitudinal bunch profiles. The fast temporal variation and small scale of these micro-structures put challenging demands on their observation. At the KIT storage ring KARA (KArlsruhe Research Accelerator), diagnostics have been developed allowing direct observation of the dynamics by an electro-optical setup, and indirect observation by measuring the fluctuation of the emitted CSR. In this contribution, we present studies of the micro-structure dynamics on simulated data, obtained using the numerical Vlasov-Fokker-Planck solver Inovesa, and first applications on measured data. To deal with generated data sets in the order of terabytes in size, we apply the machine learning technique k-means to identify the dominant micro-structures in the longitudinal bunch profiles. Following this approach, new insights on the correlation of the CSR power fluctuation to the underlying longitudinal dynamics can be gained.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK030  
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THPAK032 Elaborated Modeling of Synchrotron Motion in Vlasov-Fokker-Planck Solvers 3283
  • P. Schönfeldt, T. Boltz, A. Mochihashi, A.-S. Müller, J.L. Steinmann
    KIT, Karlsruhe, Germany
  Funding: Funded by the German Federal Ministry of Education and Research (Grant No. 05K16VKA) & Initiative and Networking Fund of the Helmholtz Association (contract number: VH-NG-320).
Solving the Vlasov-Fokker-Planck equation is a well-tested approach to simulate dynamics of electron bunches self-interacting with their own wake-field. Typical implementations model the dynamics of a charge density in a damped harmonic oscillator, with a small perturbation due to collective effects. This description imposes some limits to the applicability: Because after a certain simulation time coherent synchrotron motion will be damped down, effectively only the incoherent motion is described. Furthermore - even though computed - the tune spread is typically masked by the use of a charge density instead of individual particles. As a consequence, some effects are not reproduced. In this contribution, we present methods that allow to consider single-particle motion, coherent synchrotron oscillation, non-linearities of the accelerating voltage, higher orders of the momentum compaction factor, as well as modulations of the accelerating voltage. We also provide exemplary studies - based on the KIT storage ring KARA (KArlsruhe Research Accelerator) - to show the potential of the methods.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK032  
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THPAK042 On Long-Term Space-Charge Tracking Simulation 3305
  • J. Qiang
    LBNL, Berkeley, California, USA
  The nonlinear space-charge effects in high intensity accelerator can degrade beam quality and cause particle losses. Self-consistent macroparticle tracking simulations have been widely used to study these space-charge effects. However, it is computationally challenging for long-term tracking simulation of these effects. In this paper, we study a fully symplectic self-consistent particle-in-cell model and numerical methods to mitigate numerical emittance growth. We also discuss about a fast alternative frozen space-charge model that has a potential to improve computational speed significantly.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK042  
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THPAK043 Performance Optimization of a Beam Dynamics PIC Code On Hybrid Computer Architectures 3309
  • Zh.C. Liu
    IHEP, Beijing, People's Republic of China
  • J. Qiang
    LBNL, Berkeley, California, USA
  The self-consistent multi-particle tracking based on particle-in-cell method (PIC) has been widely used in particle accelerator beam dynamics study. However, the PIC simulation is time-consuming and needs to use modern parallel computers for high resolution applications. In this paper, we implemented and optimized a parallel beam dynamics PIC code on two types of hybrid parallel computer architectures: one is the GPU and GPU cluster, while the other is the "Knight Landing" CPU cluster.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK043  
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THPAK049 Simulation Code Design for the Interpreted Language Using the Compiled Module 3327
  • K. Fukushima, M.A. Davidsaver, Z.Q. He, M. Ikegami, G. Shen, T. Yoshimoto, T. Zhang
    FRIB, East Lansing, USA
  • J. Qiang
    LBNL, Berkeley, California, USA
  Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DESC0000661.
We are planning to use two types of the accelerator simulation codes for FRIB (Facility for Rare Isotope Beams). One is the linear envelope tracking code "FLAME" for fast simulations. FLAME can calculate the FRIB-linac beam envelope within an order of ms. This is useful in systematic surveys, wide range optimizations and so forth. This code, written in C++, was designed with Python interface from the beginning. On the other hand, "Advanced-IMPACT" is the particle tracking code dedicated for precise and realistic calculations, which can simulate the particle losses, nonlinear and space-charge effects. This code is refactored from the Fortran code IMPACT-Z developed in LBNL. Both codes provide the compiled modules for Python to support flexible inputs and direct outputs management in memory. In other words, they can be directly connected to the modern scientific tools through the Python interface without delay in the data transport. In addition, these modules can accomplish the interactive simulation processes without losing computational efficiency. We report the knowledges applicable for other accelerator simulation codes among those obtained through these developments and designs.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK049  
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THPAK050 MuSim, a User-Friendly Interface for Multiple Simulation Codes 3330
  • T.J. Roberts
    Muons, Inc, Illinois, USA
  MuSim is a new and innovative graphical framework that permits the user to construct, explore, optimize, analyze, and evaluate nuclear, accelerator, and other particle-based systems efficiently and effectively. It is designed for both students and experienced scientists to use in dealing with the many modeling tools and their different description languages and data formats. Graphical interfaces are used throughout, making it easy to construct the system graphically, display the system with particle tracks, analyze results, and use on-screen controls to vary parameters and observe their effects in (near) real time. Such exploration is essential to give users insight into how systems behave, and is valuable to both new users and experienced system designers. The use of URL-based component libraries will encourage collabor-ation among geographically diverse teams. This project will facilitate access to advanced modeling and simulation tools for inexperienced users and provide workflow management for them and advanced users.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK050  
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THPAK069 Open XAL Status Report 2018 3388
  • A.P. Zhukov, C.K. Allen, A.P. Shishlo
    ORNL, Oak Ridge, Tennessee, USA
  • C.P. Chu, Y. Li
    IHEP, Beijing, People's Republic of China
  • J.F. Esteban Müller, E. Laface, Y. Levinsen, N. Milas, C. Rosati
    ESS, Lund, Sweden
  • P. Gillette, G. Normand, A. Savalle
    GANIL, Caen, France
  • X.H. Lu
    CSNS, Guangdong Province, People's Republic of China
  The Open XAL accelerator physics software platform is being developed through an international collaboration among several facilities since 2010. The goal of the collaboration is to establish Open XAL as a multi-purpose software platform supporting a broad range of tool and application development in accelerator physics and high-level control (Open XAL also ships with a suite of general purpose accelerator applications). This paper discusses progress in beam dynamics simulation, new RF models, and updated application framework along with new generic accelerator physics applications. We present the current status of the project, a roadmap for continued development and an overview of the project status at each participating facility.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK069  
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THPAK075 Simulation of Particle Interactions in a High Intensity Radio-Frequency Quadrupole for Molecular Hydrogen Ions 3405
  • M.J. Easton, H.P. Li, Y.R. Lu, Z. Wang
    PKU, Beijing, People's Republic of China
  • J. Qiang
    LBNL, Berkeley, California, USA
  High-intensity deuteron accelerators run the risk of deuteron-deuteron interactions leading to activation. For this reason, in the commissioning phase, a molecular hydrogen ion (H2+) beam is often used as a model for the deuteron beam without the radiation risk. However, composite ions are susceptible to particle interactions that do not affect single ions, such as stripping of electrons and charge exchange. Such interactions affect the beam dynamics results, and may lead to production of secondary particles, which in high-intensity beams may cause damage to the accelerator and reduce the quality of the beam. In order to understand these effects, we have modified the IMPACT-T particle tracking code to include particle interactions during the tracking simulation through a high-intensity continuous-wave (CW) radio-frequency quadrupole (RFQ). This code is also designed to be easily extensible to other interactions, such as collisions or break-up of heavier ions. Preliminary results and possibilities for future development will be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK075  
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THPAK076 Development and Benchmarking of the IMPACT-T Code 3408
SUSPF089   use link to see paper's listing under its alternate paper code  
  • H.P. Li, M.J. Easton, Y.R. Lu, Z. Wang
    PKU, Beijing, People's Republic of China
  • J. Qiang
    LBNL, Berkeley, California, USA
  The multi-particle tracking code IMPACT-T is widely used to calculate the particle motion in high intensity linacs. The code is a self-consistent three-dimensional beam dynamics simulation toolbox that utilizes the particle-in-cell method in the time domain. In the collaboration between PKU and LBNL, an RFQ module was implemented to the IMPACT-T code, which enables simulations of the accelerator front-end. In order to benchmark the newly developed module in the IMPACT-T code, we have simulated the beam transport in Beijing Isotope Separation On-Line (BISOL) high intensity deuteron driver linac. It consists of a 3 MeV RFQ and 40 MeV superconducting HWR linac with five cryomodules. After comparing the simulation results with PARMTEQM, TraceWin and Toutatis, we obtained a very good agreement, which represents the validation of the new code.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK076  
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THPAK079 New Algorithms in Zgoubi 3418
  • D.T. Abell
    RadiaSoft LLC, Boulder, Colorado, USA
  • F. Méot
    BNL, Upton, Long Island, New York, USA
  Funding: This work was supported in part by the US Department of Energy, Office of Science, Office of Nuclear Physics under Award No. DE-SC0017181.
The particle tracking code Zgoubi*,** is used for a broad array of accelerator design studies, including FFAGs*** and EICs****,*****. In this paper, we describe recent work aimed at improving Zgoubi's speed and flexibility. In particular, we describe a new implementation of the Zgoubi tracking algorithm that requires significantly less memory and arithmetic. And we describe a new algorithm that performs symplectic tracking through field maps. In addition, we describe the current efforts to parallelize Zgoubi.
**F. Méot, FERMILAB-TM-2010, 1997
***F. Lemuet et al., NIM-A, 547:638, 2005
****F. Méot et al., eRHIC/45, 2015
*****F. Lin et al., IPAC17, WEPIK114, 2017
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK079  
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THPAK083 An s-Based Symplectic Spectral Space Charge Algorithm 3425
  • N.M. Cook, D.T. Abell, D.L. Bruhwiler, J.P. Edelen, C.C. Hall, S.D. Webb
    RadiaSoft LLC, Boulder, Colorado, USA
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics under Award Number DE-SC001340.
Traditional finite-difference particle-in-cell methods for modeling self-consistent space charge introduce non-Hamiltonian effects that make long-term tracking in storage rings unreliable. Foremost of these is so-called grid heating. Particularly for studies where the Hamiltonian invariants are critical for understanding the beam dynamics, such as nonlinear integrable optics, these spurious effects make interpreting simulation results difficult. To remedy this, we present a symplectic spectral space charge algorithm that is free of non-Hamiltonian numerical effects and, therefore, suitable for long-term tracking studies. We present initial results demonstrating the implementation of the algorithm, using a spectral representation of the fields and macro particles to preserve Hamiltonian structures. We then discuss applications to the Integrable Optics Test Accelerator (IOTA), currently under construction at Fermilab.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK083  
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THPAK087 Software-Computing System for Numerical Modelling of Beam Dynamics in Accelerators 3435
SUSPF088   use link to see paper's listing under its alternate paper code  
  • E. Krushinevskii, E. Sboeva
    Saint Petersburg State University, Saint Petersburg, Russia
  • S.N. Andrianov, A.N. Ivanov, N.V. Kulabukhova
    St. Petersburg State University, St. Petersburg, Russia
  The spectrum of software packages for the physics of charged particles beams is extremely wide. From most popular and effective systems can be allocated such programs as COSY Infinity, MAD X, MARYLIE, TRANSPORT. Heterogeneous individual formats of input and output data, the lack of a common and user-friendly interface and the narrow specialization of these programs poses a number of challenges for the modern researchers. It significantly reduces the effectiveness and quality of corresponding computational experiments. In this article we present a universal tool for automation and acceleration of computing experiments. The authors consider a method for developing the concept and prototype of a corresponding software package that would combine the advantages of existing (non-commercial) systems. This software will be able to unify the input and output data format for certain programs, visualize the information in various ways, provide reference and training information for "beginners". The results obtained within the developed framework will be a significant contribution both to the development of numerical and symbolical methods for solving evolution nonlinear equations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK087  
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THPAK088 Matrix Representation of Lie Transform in TensorFlow 3438
  • A.N. Ivanov, S.N. Andrianov, N.V. Kulabukhova, A.A. Sholokhova
    St. Petersburg State University, St. Petersburg, Russia
  • E. Krushinevskii, E. Sboeva
    Saint Petersburg State University, Saint Petersburg, Russia
  In the article, we propose an implementation of the matrix representation of Lie transform using TensorFlow as a computational engine. TensorFlow allows easy description of deep neural networks and provides automatic code execution on both single CPU/GPU and cluster architectures. In this research, we demonstrate the connection of the matrix Lie transform with polynomial neural networks. The architecture of the neural network is described and realized in code. In terms of beam dynamics, the proposed technique provides a tool for both simulation and analysis of experimental results using modern machine learning techniques. As a simulation technique one operates with a nonlinear map up to the necessary order of nonlinearity. On the other hand, one can utilize TensorFlow engine to run map optimization and system identification problems.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK088  
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THPAK107 Space-Charge Hamiltonian with a Space Coordinate as Independent Variable 3484
  • T. Planche, P. M. Jung, S.D. Rädel
    TRIUMF, Vancouver, Canada
  We present a version of the Low Lagrangian tailored to treat space-charge effects in particle accelerators: the Lagrangian is relativistic and uses a space coordinate as the independent variable. From this Lagrangian we obtain the corresponding Hamiltonian. From the Hamiltonian we obtain equations of motion for the 8 canonical variables, which can be plugged into a symplectic numerical integrator. We will finally discuss the possibility of numerically solving this problem using an explicit symplectic integrator.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK107  
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THPAK112 Toward an End-to-End Model for ISAC-I Accelerators 3500
  • O. Shelbaya, O.K. Kester
    TRIUMF, Vancouver, Canada
  Diurnal-like transmission variations in the ISAC-I warm accelerator system necessitates periodic retuning by operators. While beam loss points are well known, re-tuning nevertheless results in additional downtime and reduced count rates at experiments. This has motivated the development of an end-to-end simulation of the ISAC-I linear accelerator (linac) system to understand and characterize the nature of transmission instabilities spanning several hours to days.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK112  
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THPAK116 Modeling Surface Roughness Effects and Emission Properties of Bulk and Layered Metallic Photocathode 3515
  • D.A. Dimitrov, G.I. Bell
    Tech-X, Boulder, Colorado, USA
  • I. Ben-Zvi, J. Smedley
    BNL, Upton, Long Island, New York, USA
  • J. Feng, S.S. Karkare, H.A. Padmore
    LBNL, Berkeley, California, USA
  Funding: This work was supported by the Office of Science, Office of Basic Energy Sciences of the U.S. Department of Energy under Contract Nos. DE-SC0013190, DE-AC02-05CH11231, and KC0407-ALSJNT-I0013.
The thermal limit of the intrinsic emittance of photocathodes represents an important property to measure experimentally and to understand theoretically. Detailed measurements of intrinsic emittance have become possible in momentatron experiments. Moreover, recent developments in material design have allowed growing photoemissive layers with controlled surface roughness. Although analytical formulations of the effects of roughness have been developed, a full theoretical model and experimental verification are lacking. We aim to bridge this gap by developing realistic models for different materials in the three-dimensional VSim particle-in-cell code. We have recently implemented modeling of electron photo-excitation, transport, and emission from photoemissive layers grown on a substrate. We report results from simulations with these models on electron emission from antimony and gold. We consider effects due to density of states, photoemissive layer thickness, surface roughness and how they affect the spectral response of quantum yield and intrinsic emittance.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK116  
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THPAK118 Beam Dynamics Studies for a Strong-Focusing Cyclotron 3522
  • J. Gerity, S. Assadi, P.M. McIntyre, A. Sattarov
    Texas A&M University, College Station, USA
  Results are presented from end-to-end simulation of a 100 MeV strong focusing cyclotron (SFC). The develop-ment of the high-current SFC is motivated by applica-tions for production of medical isotopes and for a proton driver for subcritical fission. It uses a novel superconducting cavity to provide suffi-cient energy gain to fully separate all turns. An arc-contour F-D doublet, trim dipole winding, and sextupole are located along each turn within the aperture of each sector dipole to control the betatron and synchrotron motion and to stabilize non-linear dynamics with high-current operation. The phase space evolution of a proton bunch in the SFC was simulated using both the code OPAL and an ad hoc Runge-Kutta tracker. Iterative optimization of the dipole, quadrupole, and sextupole fields was used to provide precise isochronicity, favorable betatron phase advance, and cancellation of dispersion in each cell.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK118  
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THPAK129 Modeling Challenges for Energy Recovery Linacs With Long, High Charge Bunches 3544
  • C. Tennant
    JLab, Newport News, Virginia, USA
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Historically, nearly all energy recovery linacs (ERLs) built and operated were used to drive a free-electron laser (FEL). The requirement for high peak current bunches necessitates bunch compression and handling the attendant beam dynamical challenges. In recent years, ERLs have turned from being drivers of light sources toward applications for nuclear physics experiments, Compton backscattering sources and strong electron cooling. Unlike an FEL, these latter uses require long, high charge bunches with small energy spread. The electron bunch must maintain a small projected energy spread and therefore must avoid gross distortion due to CSR and longitudinal space charge over a single (or multiple) recirculations. Accurately modeling the relevant collective effects in the system 'space charge, microbunching instability, CSR and the effect of shielding' in addition to beam dynamical processes such as halo, presents a formidable challenge. Absent a code that models all of these effects, we outline an approach towards the design, analysis and optimization of the high-energy electron cooler for the Jefferson Lab Electron-Ion Collider and survey widely used codes and their capabilities.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK129  
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THPAK136 Wide-Ranging Genetic Research of Matching Line Design for Plasma Accelerated Beams with GIOTTO 3561
SUSPF090   use link to see paper's listing under its alternate paper code  
  • M. Rossetti Conti
    Universita' degli Studi di Milano & INFN, Milano, Italy
  • A. Bacci, A.R. Rossi
    Istituto Nazionale di Fisica Nucleare, Milano, Italy
  • A. Giribono, C. Vaccarezza
    INFN/LNF, Frascati (Roma), Italy
  GIOTTO is a code based on a Genetic Algorithm, being used in the field of particles accelerators for some years*-***. Its main use concerns beam-dynamics optimizations for low energy linacs, or injectors, where the beam space-charge plays an important role on its dynamics. Typical optimizations regard the Velocity Bunching technique or, more generally, the emittance and energy spread minimization. Recent improvements in GIOTTO, here discussed, have added the important capability to solve problems with a wide research domain, making GIOTTO able to design a beam Transfer Line (TL) from scratch****. The code, taking as input the TL length and the optics elements, can define the correct lattice of the line that transports and matches the beam from the linac to the undulators of an FEL, finding the right gradients, positions and dimensions for the optics elements by exploring the parameters values in selected ranges. Further, the introduction of Twiss parameters into the fitness function makes GIOTTO a powerful tool in the design of highly different beam lines. Lastly, a new routine for the statistical analysis of parameters jitters effects on the beam is under development.
*Bacci et al, NIM-B, 263, 488 (2007)
**Bacci et al, presented at PAC'07, THPAN031
***Bacci et al, presented at IPAC'16, WEPOY039
****Rossetti Conti et al, NIM-A (2018, in press)
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK136  
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THPAK144 A Pseudospectral Method for Solving the Bloch Equations of the Polarization Density in e- Storage Rings 3589
SUSPF087   use link to see paper's listing under its alternate paper code  
  • K.A. Heinemann, O. Beznosov, J.A. Ellison
    UNM, Albuquerque, New Mexico, USA
  • D. Appelö
    University of Colorado at Boulder, Boulder, USA
  • D.P. Barber
    DESY, Hamburg, Germany
  Funding: Work supported by DOE under DE-SC0018008
We consider the numerical evolution of Bloch equations for the polarization density in high-energy electron storage rings. Equilibrium polarization is well characterized by the DK formulas for current rings, but deviations may be important at the high energies we have in mind. We believe the Bloch equations derived in* give a more accurate description at all energies. These form a system of three coupled linear partial differential equations for the three components of the polarization density. Following** we formulate the equations in action-angle variables and approximate the Fokker-Planck terms. We aim to integrate these equations numerically in order to approximate the equilibrium and compare with the DK formulas. The smoothness and simple geometry of the problem makes it amenable to pseudospectral discretization using Fourier modes in the angles and Chebyshev polynomials in the actions, leading to a large ODE system. We will explore time stepping algorithms for the needed long time integration. Here, we present results for simple models checking the accuracy of the numerical method but note that our ultimate goal is to simulate polarization in the FCC and CEPC rings.
* Ya.S.Derbenev, A.M.Kondratenko, Sov. Phys. Dokl., 19, p.438 (1975).
** D.P.Barber, K.Heinemann, H.Mais, G.Ripken,
A Fokker-Planck treatment of stochastic particle motion…,
DESY-91-146, 1991.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK144  
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