Keyword: simulation
Paper Title Other Keywords Page
SURDI1 Computational Challenges in ESS linac, cavity, cryomodule, rfq 1
 
  • H. Danared, M. Eshraqi, E. Laface, R. Miyamoto, S. Molloy, A. Ponton
    ESS, Lund, Sweden
  
  The European Spallation Source, to be built in Lund, Sweden, will be based on a superconducting proton linac. Top-level linac parameters of 2.5 GeV energy, 50 mA pulse current, 14 Hz pulse repetition rate and 2.86 ms pulse length result in 5 MW average beam power and 125 MW peak power. General challenges for the accelerator design and construction range from minimizing beam losses to prototyping, manufacturing and installing the large quantity of RF power soures. The presentation will give an overview of the ESS project and give specific examples of computational challenges related to the beam dynamics of the linac.  
slides icon Slides SURDI1 [11.623 MB]  
 
MOAAI1 Project Overview and Computational Needs to Measure Electric Dipole Moments at Storage Rings storage-ring, dipole, proton, synchrotron 7
 
  • A. Lehrach
    FZJ, Jülich, Germany
  
  The discovery of a non-zero EDM (Electric Dipole Moment) would be a signal for “new physics” beyond the standard model. EDM experiments with charged particles are only possible at storage rings. As a first step towards EDM searches in storage rings we proposed R&D work to be carried out at the Cooler Synchrotron COSY, then perform a first direct EDM measurement of a charged particle in a storage ring at COSY and on a longer time scale construct a dedicated storage ring. Full spin-tracking simulations of the entire experiment are absolutely crucial to explore the feasibility of the planned experiments. It is planned to use the COSY-INFINITY code and its updates to include higher-order nonlinearities, normal form analysis, symplectic tracking and especially spin tracking upon incorporation of RF-E/B spin flippers into the code. Adding the spin degree of freedom substantially enhances the need for the computing power. In order to study subtle effects and simulate particle and spin dynamics during the storage and build-up of the EDM signal, one needs custom-tailored fast trackers capable of following up to 100 billion turns for samples of up to 106 particles.  
slides icon Slides MOAAI1 [3.341 MB]  
 
MOABC3 Simulating the LHC Collimation System with the Accelerator Physics Library MERLIN, and Loss Map Results proton, collimation, scattering, optics 12
 
  • J. Molson, R. Appleby, M. Serluca, A.M. Toader
    UMAN, Manchester, United Kingdom
  • R.J. Barlow
    University of Huddersfield, Huddersfield, United Kingdom
  
  Funding: FP7 EUCARD Cockcroft Institute
We present large scale simulations of the LHC collimation system using the MERLIN code for calculations of loss maps, currently using up to 1.5·109 halo particles. In the dispersion suppressors following the collimation regions, protons that have undergone diffractive interactions can be lost into the cold magnets. This causes radiation damage and could possibly cause a magnet quench in the future with higher stored beam energies. In order to correctly simulate the loss rates in these regions, a high statistics physics simulation must be created that includes both accurate beam physics, and an accurate description of the scattering of a 7 TeV proton in bulk materials. The current version includes the ability to simulate new possible materials for upgraded collimators, and advances to beam-collimator interactions, including proton-nucleus interactions using the Donnachie-Landshoff Regge-Pomeron scattering model. Magnet alignment and field errors are included, in addition to collimator jaw alignment errors, and their effects on the beam losses are systematically estimated. Collimator wakefield simulations are now fully parallel via MPI, and many other speed enhancements have been made. 		 
slides icon Slides MOABC3 [8.057 MB]  
 
MOSBC2 Linac Beam Dynamics Simulations with PyORBIT linac, lattice, space-charge, cavity 20
 
  • A.P. Shishlo
    ORNL, Oak Ridge, Tennessee, USA
  
  Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under Contract No. DE-AC05-00OR22725
Linac dynamics simulation capabilities of the PyORBIT code are discussed. The PyORBIT is an open source and a further development of the original ORBIT code that was developed and used for design, studies, and commissioning of the SNS ring. The PyORBIT code like the original one has a two layers structure. The C++ is used to perform time consuming computations, and a program flow is controlled from the Python language shell. The flexible structure allowed using the PyORBIT also for linac dynamics simulations. The benchmark of the PyORBIT with Parmila and the XAL Online model is presented. 		 
slides icon Slides MOSBC2 [1.857 MB]  
 
MOSBC3 An Implementation of the Virtual Accelerator in the Tango Control System controls, lattice, diagnostics, storage-ring 23
 
  • P.P. Goryl, A.I. Wawrzyniak
    Solaris, Kraków, Poland
  • M. Sjöström
    MAX-lab, Lund, Sweden
  • T. Szymocha
    Cyfronet, Kraków, Poland
  
  Funding: Work supported by the European Regional Development Fund within the frame of the Innovative Economy Operational Program: POIG.02.01.00-12-213/09
Integration of simulating codes into the control system gives a possibility to improve machine operation. Providing tools for making computations directly within the control system and letting exchange data between the control system and models is a way of simplifying the whole process of calculating and applying machine's operational parameters as well as keeping track of them. In addition, having so-called an on-line model could be useful for system diagnostic and faults detection, especially when the objective approach is considered. The concept of the Virtual Accelerator will be presented as well as its implementation for the Tango control system as it is planned to be used for both facilities: the Solaris in Kraków, Poland and the MAX IV in Lund, Sweden. This includes the ModelServer tango device, the simplified C/C++ Tango API to be used with codes like Tracy and the tango2elegant script providing easy solution for integrating the Elegant tool with the Tango. 		 
slides icon Slides MOSBC3 [2.232 MB]  
 
MOACC2 Simulation of Electron Cloud Instability electron, solenoid, positron, betatron 26
 
  • K. Ohmi
    KEK, Ibaraki, Japan
  
  We discuss coupled bunch and single bunch instabilities caused by electron cloud in positron and proton circular accelerator. We focus unstable mode spectrum which characterizes the instabilities.  
slides icon Slides MOACC2 [3.432 MB]  
 
MOACC3 Tracking of a PETRA III Positron Bunch with a Pre-Computed Wake Matrix due to Electron Clouds emittance, electron, positron, wakefield 31
 
  • A. Markoviḱ, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  
  Funding: Work supported by DFG under contract number RI 814/20-2.
At the synchrotron radiation facility at DESY transversal tune spectra have been observed which are characteristic for an interaction of the positron beam with possible electron clouds in the ring. The filling patterns at which this incoherent tune shifts happen are favourable to the growth of the electron density, i.e. long bunch trains with short intra-bunch distances or filling with short trains but also short distances between the trains. Eventually the vertical emittance growth with the originally designed equidistant filling (with 8 or 16 ns bunch spacing) has been avoided by fillings with shorter trains and longer gaps between the trains by still achieving the designed beam current of 100 mA. In this paper we examine the positron bunch stability of PETRA III for certain e-cloud densities and bunch parameters. A PIC simulation of the interaction of the bunch with an e-cloud yields the wake kick on the tail particles for an offset in the transverse centroid position of the head parts. With such a pre-computed wake matrix, we investigate the stability of a single bunch by tracking it through the linear optics of the ring while at each turn applying the kick from the e-cloud. 		 
slides icon Slides MOACC3 [5.237 MB]  
 
MOSCC2 Simulation of Space Effects During Multiturn Injection into the GSI SIS18 Synchrotron injection, emittance, space-charge, septum 37
 
  • S. Appel
    GSI, Darmstadt, Germany
  • O. Boine-Frankenheim
    TEMF, TU Darmstadt, Darmstadt, Germany
  
  The optimization of the Multiturn Injection (MTI) from the UNILAC into the SIS18 is crucial in order to reach the FAIR beam intensities required for heavy ions. In order to achieve the design intensities, the efficiency of the multiturn injection from the UNILAC has to be optimized for high beam currents. We developed a simulation model for the MTI including the closed orbit bump, lattice errors, the parameters of the injected UNILAC beam, the position of the septum and other aperture limiting components, and finally the space charge force and other high-intensity effects. The model is also used to estimate the required proton and heavy-ion beam emittances from the UNILAC and from the projected p-linac. For the accurate prediction of the MTI efficiency a careful validation of the simulation model is necessary. We will present first results of the comparison between experiments and simulation for low and high uranium beam currents.  
slides icon Slides MOSCC2 [2.511 MB]  
 
MOSCC3 Low-energy p-He and mu-He Simulation in Geant4 scattering, proton, plasma, electron 40
 
  • Y. Bao
    PSI, Villigen, Switzerland
  
  The frictional cooling method is one of the most promising methods on cooling a muon beam. Several frictional cooling schemes have been simulated in Geant4 to be efficient to produce intense muon beams. Frictional cooling works at a low energy range, where the energy loss (momentum transfer) from elastic collision is not negligible. In this paper, the p-He collision process is implemented into Geant4 and the simulation results are compared to the literature data. The cross section is then scaled for mu-He interaction, which will provide more accurate Geant4 simulations at low energies.  
slides icon Slides MOSCC3 [0.665 MB]  
 
MOADI1 High Precision Cavity Simulations cavity, impedance, resonance, coupling 43
 
  • W. Ackermann, T. Weiland
    TEMF, TU Darmstadt, Darmstadt, Germany
  
  Funding: Work supported by DESY, Hamburg
The design and optimization of particle accelerator components are fundamentally based on beam dynamics simulations. The knowledge of the interaction of moving charged particles with the surrounding materials and fields enables to optimize individual devices and consequently to take the best advantage of the entire machine. Among the essential accelerator components are radio-frequency cavities which are utilized for acceleration as well as for beam diagnostics. In these applications, precise beam dynamics simulations urgently require high-precision data of the electromagnetic fields. Numerical simulations based on Maxwell’s equations have to represent the resulting fields on an acceptable level of quality even with limited amount of degrees of freedom. On the other hand, the particle beam itself gives rise to the excitation of undesired modes which have to be extracted from the cavities. In the current work, some of the challenges faced in high precision cavity simulations are summarized. Based on high-performance eigenvalue calculations, important features like "low-noise" field evaluations or port-mode boundary approximations to enable traveling-wave transport are addressed. 		 
slides icon Slides MOADI1 [4.234 MB]  
 
MOADC2 Implementational Aspects of Eigenmode Computation Based on Perturbation Theory cavity, factory, electromagnetic-fields 48
 
  • K. Brackebusch, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  
  Funding: Work supported by Federal Ministry for Research and Education BMBF under contracts 05H09HR5 and 05K10HRC.
Geometry perturbations affect the eigenmodes of a resonant cavity and thereby can improve but also impair the performance characteristics of the cavity. To investigate the effects of both, intentional and inevitable geometry variations parameter studies are to be undertaken. Using common eigenmode solvers involves to perform a full eigenmode computation for each variation step, even if the geometry is only slightly altered. Therefore, such investigations tend to be computationally extensive and inefficient. Yet, the computational effort for parameter studies may be significantly reduced by using perturbative computation methods. Knowing a set of initial eigenmodes of the unperturbed geometry these allow for the expansion of the eigenmodes of the perturbed geometry in terms of the unperturbed modes. In this paper, we study the complexity of a numerical implementation of perturbative methods. An essential aspect is the computation and analysis of the unperturbed modes since the number and order of these modes determine the accuracy of the results. 		 
slides icon Slides MOADC2 [2.431 MB]  
 
MOSDI1 Analyzing Multipacting Problems in Accelerators using ACE3P on High Performance Computers cavity, gun, electron, SRF 54
 
  • L. Ge, C. Ko, K.H. Lee, Z. Li, C.-K. Ng, L. Xiao
    SLAC, Menlo Park, California, USA
  
  Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
Track3P is the particle tracking module of ACE3P, a 3D parallel finite element electromagnetic code suite developed at SLAC which has been implemented on the US DOE supercomputers at NERSC to simulate large-scale complex accelerator designs. Using the higher-order cavity fields generated by ACE3P codes, Track3P has been used for analyzing multipacting (MP) in accelerator cavities. The prediction of the MP barriers in the ICHIRO cavity at KEK was the first Track3P benchmark against measurements. Using a large number of processors, Track3P can scan through the field gradient and cavity surface efficiently, and its comprehensive postprocessing tool allows the identifications of both the hard and soft MP barriers and the locations of MP activities. Results from applications of this high performance simulation capability to accelerators such as the Quarter Wave Resonator for FRIB, the 704 MHz SRF gun cavity for BNL ERL and the Muon cooling cavity for Muon Collider will be presented. 		 
 
MOSDC2 GPGPU Implementation of Matrix Formalism for Beam Dynamics Simulation controls, target 59
 
  • N.V. Kulabukhova
    St. Petersburg State University, St. Petersburg, Russia
  
  Matrix formalism is a map integration method for ODE solving. It allows to present solution of the system as sums and multiplications of 2-indexes numeric matrix. This approach can be easy implement in parallel codes. As the most natural for matrix operation GPU architecture has been choosen. The set of the methods for beam dynamics has been implemented. Particles and envelope dynamics are supported. The computing facilities are located in St. Petersburg State University and presented by the NVIDIA Tesla clusters.  
slides icon Slides MOSDC2 [0.770 MB]  
 
TUAAI2 A Massively Parallel General Purpose Multi-objective Optimization Framework, Applied to Beam Dynamic Studies emittance, status, controls, solenoid 62
 
  • Y. Ineichen, A. Adelmann
    PSI, Villigen, Switzerland
  • P. Arbenz
    ETH, Zurich, Switzerland
  • C. Bekas, A. Curioni
    IBM Research - Zurich, Rueschlikon, Switzerland
  
  Particle accelerators are invaluable tools for research in basic and applied sciences. The successful design, commissioning, and operation of accelerator facilities is non trivial. We implemented a framework for general simulation-based multi-optimization methods automating the investigation of optimal sets of machine parameters. In order to solve the emerging, huge problems we propose a massively-parallel master/slave approach. We employ the framework to identify optimal parameters of existing and new accelerators at PSI.  
slides icon Slides TUAAI2 [0.694 MB]  
 
TUABI1 The TRIUMF Optimization Platform and Application to the E-linac Injector TRIUMF, linac, cryomodule, FEL 67
 
  • C. Gong, Y.-C. Chao
    TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
  
  Funding: Funding is received from Natural Sciences and Engineering Research Council of Canada for this research.
Multi-objective genetic algorithms (MOGA) have demonstrated their usefulness for the global optimization of accelerator design using Elegant and Astra. A MOGA platform developed at TRIUMF seeks to expand the capabilities of such tools by allowing multiple simulation engines to be used. The TRIUMF optimization software platform was applied to the transport design of an injection line leading from a cryomodule to the beam dump. The optimization involves two simulation engines, Astra and MAD-X, and demonstrates the ability for the platform to handle multi-engine optimization for a realistic problem. Results of the optimization are shown. 		 
slides icon Slides TUABI1 [1.132 MB]  
 
TUABC3 Multi-Objective Genetic Optimization of Linac Beam Parameters for a seeded FEL linac, FEL, laser, electron 75
 
  • M. Apollonio, R. Bartolini, I.P.S. Martin
    Diamond, Oxfordshire, United Kingdom
  
  The optimization of the beam dynamics in a Linac for free electron lasers (FELs) can be a very time consuming process, in which several parameters of the acceleration and compression sections need to be varied simultaneously. The optimization procedure is required to tackle different and often opposite goals at a time, depending on the adopted FEL scheme. As such, multi-objective genetic algorithms are an interesting choice, given their ability to targeting several, often conflicting objectives. We have studied an optimization strategy based on a combination of multi-objective optimization with a fast parallel computation of the FEL performance and, for the specific case of the proposed UK’s New Light Source, we illustrate the benefits of this method for the optimization of the average gain length and its variation along the beam pulse. The method can be extended to other sets of objectives, such as power and bandwidth of the FEL.  
slides icon Slides TUABC3 [5.567 MB]  
 
TUSBC2 Low Noise Particle-in-Cell Simulations of Laser Plasma Accelerator 10 GeV Stages plasma, emittance, laser, electron 78
 
  • E. Cormier-Michel, D.L. Bruhwiler, J.R. Cary, B.M. Cowan, E.J. Hallman
    Tech-X, Boulder, Colorado, USA
  • E. Esarey, C.G.R. Geddes, W. Leemans, C.B. Schroeder, J.-L. Vay
    LBNL, Berkeley, California, USA
  
  Funding: Work supported by DOE/HEP, under grants DE-SC0004441 and DE-FC02-07ER41499, including use of NERSC under DE-AC02-05CH11231.
Because of their ultra-high accelerating gradient, laser plasma based accelerators (LPA) are contemplated for the next generation of high-energy colliders and light sources. The upcoming BELLA project will explore acceleration of electron bunches to 10 GeV in a 1 meter long plasma, where a wakefield is driven by a PW-class laser. Particle-in-cell (PIC) simulations are used to design the upcoming experiments where boosted frame simulations are used to model the full scale stages. As criteria on energy spread and beam emittance become more stringent, PIC simulations become more challenging as high frequency noise artificially increases those quantities. We show that calculating the beam self-fields using a static Poisson solve in the beam frame dramatically reduces particle noise, allowing for more accurate simulation of the beam evolution. In particular, this method gets correct cancellation of the transverse self-electric and magnetic fields of the beam, eliminating artificial self-forces, which is usually not true when using the standard PIC algorithm based on the staggered (“Yee”) electromagnetic field solver. 		 
slides icon Slides TUSBC2 [5.989 MB]  
 
TUACI1 Numerical Modeling of Collective Effects in Free Electron Laser FEL, undulator, radiation, electron 81
 
  • I. Zagorodnov
    DESY, Hamburg, Germany
  
  In order to have a free electron laser (FEL) of high performance we need to design and optimize it taking into account the dynamics of electrons and their interactions with each other and with their surroundings. An accurate self-consistent simulation of collective effects in the charged beams remains a challenging problem for numerical analysis. In this paper we consider only the modeling of FEL process in an undulator section. We give a short overview of the numerical methods adopted in different FEL codes. Advantages and drawbacks of these methods will be discussed. Some approaches to improve the accuracy and efficiency of the codes will be presented and the remaining challenges in FEL modeling will be highlighted.  
slides icon Slides TUACI1 [2.659 MB]  
 
TUADI1 Storage Ring EDM Simulation: Methods and Results lattice, storage-ring, factory, proton 99
 
  • Y. Senichev, A. Lehrach, R. Maier, D. Zyuzin
    FZJ, Jülich, Germany
  • S.N. Andrianov, A.N. Ivanov
    St. Petersburg State University, St. Petersburg, Russia
  • M. Berz, K. Makino
    MSU, East Lansing, Michigan, USA
  
  The idea of Electric Dipole Moment search using the electrostatic storage ring with polarized beam is based on accumulation of additional tiny spin rotation, about one-billionth of radians per second, occurred only in the presence of EDM. This method can be realized under condition of the long-time spin coherency ~1000 seconds. During this time each particle performs about 109 turns in ring moving on different trajectories. At such conditions the spin-rotation aberrations associated with various types of space and time dependent nonlinearities start playing a crucial role. To design such a ring the computer simulation is necessary taking into account all factors affecting the spin. We used COSY-Infinity and integrating program with symplectic Runge-Kutta methods in composition with analytic methods. We developed a new lattice based on the alternating spin rotating. As a result, we can achieve the SCT of ~5000 seconds. The difficulties of these studies are still in the fact that the aberrations growth is observed in the scale of 109 turns and few million particles. For this simulation we use a supercomputer with parallel computing process.  
slides icon Slides TUADI1 [0.951 MB]  
 
TUADC3 Implementing New Beam Line Elements into a Moment Method Beam Dynamics Code rfq, quadrupole, insertion, radio-frequency 104
 
  • T. Roggen, H. De Gersem, B. Masschaele
    KU Leuven, Kortrijk, Belgium
  • W. Ackermann, S. Franke, T. Weiland
    TEMF, TU Darmstadt, Darmstadt, Germany
  
  Funding: This research is funded by grant "KUL 3E100118" "Electromagnetic Field Simulation for Future Particle Accelerators".
Developing beam dynamics simulation tools using the moment method has advantages in terms of precision and efficiency when interests lie in average or rms dimensions of the beam, projected emittances or total energy. The moment method implemented in the V-Code solves the Vlasov equation by time integration, from an initial particle distribution represented by a discrete set of characteristic moments, accounting for all acting internal and external forces along the particle's path. The moment method delivers highly accurate beam dynamics results within a very small CPU time. This article proposes, illustrates and validates a new beam line element for a radiofrequency quadrupole (RFQ) for insertion in the V-Code. The focus will be on the RFQ cell structure, the electric field distribution and the insertion of the field distribution in the moment code. 		 
slides icon Slides TUADC3 [4.387 MB]  
 
TUSDC2 Rapid Integration Over History in Self-consistent 2D CSR Modeling radiation, shielding 112
 
  • K.A. Heinemann, D. Bizzozero, J.A. Ellison, S.R. Lau
    UNM, Albuquerque, New Mexico, USA
  • G. Bassi
    BNL, Upton, Long Island, New York, USA
  
  Funding: This work has been supported by DOE under DE-FG-99ER41104
In our self-consistent algorithm for calculating 2D CSR effects we reduce the field calculation to a 2D integral over the 2D charge and current densities of the bunch and their time history. Our code VM3@A (Vlasov-Maxwell Monte-carlo Method @ Albuquerque) implements this in a time stepping algorithm as discussed in PRST-AB 12, 080704 (2009). A major expense is the integration over history at each time step. By going to Fourier space the 2D integral is reduced to a 1D convolution over history. This may on its own have a computational advantage, however, using the kernel compression technique of Alpert, Greengard and Hagstrom [1, 2], we approximate the convolution kernel by a sum of exponentials. This allows a time step to be taken using information only from the previous time step, thus eliminating the integral over history. Of course 2D Fourier transforms must be calculated at each step, these can be done with an FFT (or NFFT). We discuss the flop count for the two approaches. In addition we implement this as an option in VM3@A and compare efficiencies of our new and old approaches in the context of a bunch compressor system for the LCLS.
[1] SIAM J. Numer. Anal. 37(2000) 1138. See also PhD thesis at http://web.njit.edu/~jiang/pub.html
[2] S. R. Lau, J. Math. Phys. 46, 102503, (2005). Supported by DE-FG02-99ER41104 		 
slides icon Slides TUSDC2 [0.485 MB]  
 
WEAAC2 Simulation of Baseband BTFs Using a Particle-in-cell Code beam-beam-effects, lattice, proton, diagnostics 121
 
  • P.A. Görgen
    TEMF, TU Darmstadt, Darmstadt, Germany
  • O. Boine-Frankenheim
    GSI, Darmstadt, Germany
  • W. Fischer, S.M. White
    BNL, Upton, Long Island, New York, USA
  
  A simulation model for transverse bunched beam transfer functions (BTFs) at the base harmonic is presented. It is based on a code including different machine effects, most notably transverse space charge using a two-dimensional (2D) Poisson solver. A simplified model for the simulation of the strong-strong beam-beam effect was implemented using either 2D field data or analytic expressions under the assumption of Gaussian beams for the beam-beam interaction. The validity of the BTF model is verified based on the comparison of BTF and Schottky spectra features with analytic expectations from literature. The simulation model is then applied to the RHIC proton lattice. A linear transfer map is used between interaction points. BTFs including the beam-beam effect are simulated. Measurements are compared to simulation results at machine conditions.  
slides icon Slides WEAAC2 [2.829 MB]  
 
WEAAC3 Dynamics of Ferrite Cavities and their Effect on Longitudinal Dipole Oscillations cavity, controls, resonance, synchrotron 124
 
  • C. Spies, M. Glesner
    TUD, Darmstadt, Germany
  • U.K. Hartel, H. Klingbeil
    TEMF, TU Darmstadt, Darmstadt, Germany
  • H.G. König
    GSI, Darmstadt, Germany
  
  Funding: This work is supported by the German Federal Ministry of Education and Research under grant number 06DA9028I.
In a synchrotron, particles are accelerated by repeatedly passing through RF cavities. In the SIS18 synchrotron at GSI, ferrite cavities are used. Each cavity is equipped with local control systems to adjust the amplitude and phase of the accelerating field. In this paper, we consider ferrite cavities of the type that is currently used in the SIS18 at GSI and will be used in the future SIS100 which is being built in the frame of the FAIR project. We analyze the dynamics of the cavities in conjunction with their local control loops. An emphasis is put on the cavities' reaction to changes in the desired amplitude or resonant frequency. Using simulations, we show that the cavities' dynamics hardly influence longitudinal dipole oscillations, and conclude that a high-level model for the RF cavities is sufficient. 		 
slides icon Slides WEAAC3 [1.055 MB]  
 
WESAI2 Space Charge and Electron Cloud Simulations electron, resonance, space-charge, proton 130
 
  • G. Franchetti
    GSI, Darmstadt, Germany
  • F. Zimmermann
    CERN, Geneva, Switzerland
  
  Funding: AccNet
Tracking of high intensity effects for few turns of a circular accelerator is at reach of present computational capabilities. The situation is very different when the prediction of beam behaviour is extended to hundred of thousands of turns, where special approaches for the control of computer artifact are necessary sometimes to the expense of a complete physical modeling. The identification of the key physical ingredients helps to the development of computer algorithms capable of treating the long term tracking. In this talk it is presented the actual state of simulations for long term tracking of high intensity bunches of the SIS100 addressing the self consistent treatment of beam loss. A more realistic modeling of the incoherent effect of electron cloud is addressed as well. 		 
slides icon Slides WESAI2 [7.523 MB]  
 
WESAI3 Simulating the Wire Compensation of LHC Long-range Beam-beam Effects optics, beam-beam-effects, resonance, luminosity 135
 
  • T.L. Rijoff, F. Zimmermann
    CERN, Geneva, Switzerland
  
  The performance of the Large Hadron Collider (LHC) and its minimum crossing angle are limited by long-range beam-beam collisions. Wire compensators can mitigate part of the long-range effects. We perform simulations to explore the efficiency of the compensation at possible wire locations by examining the tune footprint and the dynamic aperture. Starting from the weak-strong simulation code BBTrack we developed a new Lyapunov calculation tool, which seems to better diagnose regular or chaotic particle behavior. We also developed faster ways to execute the simulation and the post-processing. These modifications have allowed us to study different wire positions (longitudinal and transverse), varying wire currents, several wire shapes, and a range of beam-beam crossing angles, in view of a prototype wire installation in the LHC foreseen for 2014/15. Our simulations demonstrate that the wire can provide a good compensation,also for reduced crossing angle. Benefits of an LHC wire compensator include a better overlap of colliding bunches,as well as the possibility of smaller β* or higher beam current  
slides icon Slides WESAI3 [17.486 MB]  
 
WESAI4 Electron Cloud Simulations with PyECLOUD electron, ISOL, collider, hadron 138
 
  • G. Iadarola
    Naples University Federico II, Science and Technology Pole, Napoli, Italy
  • G. Rumolo
    CERN, Geneva, Switzerland
  
  PyECLOUD is a newly developed code for the simulation of the electron cloud (EC) build-up in particle accelerators. Almost entirely written in Python, it is mostly based on the physical models already used in the ECLOUD code but, thanks to the implementation of new optimized algorithms, it exhibits a significantly improved performance in accuracy, speed, reliability and flexibility. PyECLOUD simulations have been already broadly employed for benchmarking the EC observations in the Large Hadron Collider (LHC). Thanks to the new feature of running EC simulations with bunch-by-bunch length and intensity data from machine measurements, the “scrubbing” process of the LHC beam pipes could be reconstructed from heat load measurements in the cryogenic dipoles. In addition, PyECLOUD simulations also provide the estimation of the bunch-by-bunch energy loss, which can be compared with the measurements of the stable phase shift. They can also provide the correct EC distribution data for beam dynamics simulations with the HEADTAIL code.  
slides icon Slides WESAI4 [3.466 MB]  
 
WEP01 Simulations for Ion Clearing in an ERL ion, electron, vacuum, linac 143
 
  • G. Pöplau, A. Markoviḱ, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • A. Meseck
    HZB, Berlin, Germany
  
  Funding: supported by BMBF under contract no. 05K10HRC
Energy Recovery Linacs (ERLs) being the most promising candidates for next-generation light sources put very high demands on preservation of beam brightness and reduction of beam losses. Thus, it is mandatory to avoid the impact of ionized residual gas considered as a source for instabilities in accelerators. Recently, we have presented simulations for the clearing of ionized residual gas with electrodes performed with an upgraded version of software package MOEVE PIC Tracking [1] which is being currently further developed to model the interaction of the ions with the electron beam in presence of external electromagnetic potentials such as the field of clearing electrodes. The tracking code allows for studies on clearing times for electrodes with different voltage as well as detailed studies of the behavior of the ions in the environment of the electrodes. In this paper we take further steps to study possible designs of clearing electrodes. Especially, we will consider the influence of different gas mixtures on clearing times and possible configurations for the clearing electrodes. We use parameters planned for BERLinPro as an example for our studies.
[1] G. Pöplau, A. Meseck, U. van Rienen, Simulation of the Behavior of Ionized Residual Gas in the Field of Electrodes, IPAC 2012, New Orleans. 		 
 
WEP02 Numerical Studies on the Influence of Fill Patterns on Ion Clouds ion, electron, vacuum, emittance 146
 
  • A. Meseck
    HZB, Berlin, Germany
  • G. Pöplau, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  
  Funding: supported by BMBF under contract no. 05K10HRC
Energy Recovery Linacs (ERLs) are the most promising candidates for next-generation light sources now under active development. An optimal performance of these machines requires the preservation of the high beam brightness generated in the injector. For this, the impact of the ionized residual gas on the beam has to be avoided as it causes instabilities and emittance growth. Obviously, the vacuum chamber has to be cleared out of ions but as the potential of the electron beam attracts the ions, it is not enough to install vacuum pumps. One measure for ion clearing are gaps in the bunch train long enough that the ions have time to escape the force of the bunch potential. In this paper, we present numerical studies of the behavior of an ion cloud that interacts with a bunch train. Especially, we consider different distributions for the particles in the bunch, different fill patterns and several mixtures of ions in the residual gas. The simulations are performed with the package MOEVE PIC Tracking. The presented numerical investigations take into account the parameters of the ERL BERLinPro with the objective to deduce appropriate measures for the design and operation of BERLinPro. 		 
 
WEP06 Particle Tracking in Electrostatic Fields with Energy Conservation controls, quadrupole, storage-ring, lattice 149
 
  • A.N. Ivanov
    St. Petersburg State University, St. Petersburg, Russia
  
  The key idea of the research is to consider spin dynamics in electrostatic fields. Due to the fact, that spin rotation frequency explicitly depends on velocity of the particle and its kinetic energy is changed in electrostatic fields it is important to use some technique that provides both conservation energy and symplicticity condition. An appropriate mathematical model is described and the results of numerical calculation are shown. In conclusion, fringe fields influence is examined and compared with case of ideal fields.  
 
WEP07 Traveling Poles Elimination Scheme and Calculations of External Quality Factors of HOMs in SC Cavities cavity, HOM, factory, linac 152
 
  • T. Galek, T. Flisgen, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • A. Neumann
    HZB, Berlin, Germany
  • B. Riemann
    DELTA, Dortmund, Germany
  
  Funding: Funded by EU FP7 Research Infrastructure Grant No. 227579 and funding approved by German Federal Ministry of Research & Education, Project: 05K10HRC
The main scope of this work is the automation of the extraction procedure of the external quality factors Qext of Higher Order Modes (HOMs) in Superconducting (SC) radio frequency cavities [*]. The HOMs are generated by charged particle beams traveling at the speed of light through SC cavity. The HOMs decay very slowly, depending on localization inside the structure and cell-to-cell coupling, and may influence succeeding charged particle bunches. Thus it is important, at the SC cavity design optimization stage, to calculate the Qext of HOMs. The Traveling Poles Elimination (TPE) scheme has been used on scattering parameters spectra to obtain external quality factors. The combination of Coupled S-Parameter Calculations (CSC) method and vector fitting procedure allows us to study very complicated structures in much better details and almost automated extraction of HOMs' Qext factors. The results are also reasserted by careful eigenmode analysis of the SC cavity. The S-Parameter and eigenmode simulations were performed using CST Microwave Studio.
*Axel Neumann et al., "Status of the HOM Calculations for the BERLinPro Main Linac Cavity", FRAAC3 (this conference) 		 
 
WEP08 Comparison of Different Electromagnetic Solvers for Accelerator Simulations wakefield, gun 155
 
  • J. Xu, R. Zhao, X. Zhufu
    IS, Beijing, People's Republic of China
  • C. Li, X. Qi, L. Yang
    IMP, Lanzhou, People's Republic of China
  • M. Min
    ANL, Argonne, USA
  
  Funding: Chinese Academy of Science
Electromagnetic simulations are fundamental for accelerator modeling. In this paper two high-order numerical methods will be studied. These include continuous Galerkin (CG) method with vector bases, and discontinuous Galerkin (DG) method with nodal bases. Both methods apply domain decomposition method for the parallelization. Due to the difference in the numerical methods, these methods have different performance in speed and accuracy. DG method on unstructured grid has the advantages of easy parallelization, good scalability, and strong capability to handle complex geometries. Benchmarks of these methods will be shown on simple geometries in detail first. Then they will be applied for simulation in accelerator devices, and the results will be compared and discussed. 		 
 
WEP11 Stochastic Response Surface Method for Studying Microphoning and Lorenz Detuning of Accelerator Cavities cavity, radiation, SRF, insertion 158
 
  • J. Deryckere, H. De Gersem, B. Masschaele, T. Roggen
    KU Leuven, Kortrijk, Belgium
  
  Funding: This research is funded by grant KUL_3E100118 and grant KUL_3E080005.
The dependence of the eigenfrequencies of a superconductive cavity on its geometry are represented by a stochastic response surface model. The model is constructed on the basis of both information on the eigenfrequencies as on their sensitivities with respect to the geometry. The eigenmodes are calculated using the 2D or 3D finite element method or finite integration technique. The stochastic representation does not only model uncertainties on the geometrical parameters but also inaccuracies of the eigenmode solvers, e.g. due to remeshing. Variations or optimisations of the geometry are carried out on the surrogate model. The model allows an efficient evaluation of microphoning and Lorentz detuning of accelerator cavities. 		 
poster icon Poster WEP11 [0.665 MB]  
 
WEP12 Realistic 3-Dimensional Eigenmodal Analysis of Electromagnetic Cavities using Surface Impedance Boundary Conditions cavity, impedance, resonance, radio-frequency 161
 
  • H. Guo, B.S.C. Oswald
    PSI, Villigen, Switzerland
  • P. Arbenz
    ETH, Zurich, Switzerland
  
  Funding: The work of the first author (H. Guo) was supported in part by grant no. 200021-117978 of the Swiss National Science Foundation.
The new X-ray Free Electron Laser (SwissFEL) at the Paul Scherrer Institute (PSI) employs, among many other radio frequency elements, a transverse deflecting cavity for beam diagnostics. Since the fabrication process is expensive, an accurate 3-D eigenmodal analysis is indispensable. The software package Femaxx has been developed for solving large scale eigenvalue problems on distributed memory parallel computers. Usually, it is sufficient to assume that the tangential electric field vanishes on the cavity wall. To better approximate reality, we consider the cavity wall conductivity is large but finite, and thus the tangential electrical field on the wall is nonzero. We use the surface impedance boundary conditions (SIBC) arising from the skin-effect model. The resulting nonlinear eigenvalue problem is solved with a nonlinear Jacobi–Davidson method. We demonstrate the performance of the method. First, we investigate the fundamental mode of a pillbox cavity. We study resonance, skin depth and quality factor as a function of the cavity wall conductivity. Second, we analyze the transverse deflecting cavity to assess the capability of the method for technologically relevant problems. 		 
 
WEACI1 Design and Applications of the Bmad Library for the Simulation of Particle Beams and X-Rays lattice, solenoid, controls, quadrupole 179
 
  • D. Sagan
    CLASSE, Ithaca, New York, USA
  
  The Bmad software library has been developed for simulations of high-energy particle beams along with simulations of the x-rays produced by the particle beams. Owing to its modular, object-oriented design, Bmad is now used in a number of programs at Cornell's Laboratory for Elementary-Particle Physics. This paper will discuss the design of the Bmad library. Features such as the ability to have overlapping elements, the ability to define in a lattice file the action of control-room ‘‘knobs'', and the ability to choose from a number of different tracking options on an element-by-element basis have all contributed to a versatile simulation environment that eases the task of programmers and users using Bmad. Also discussed is the uses that Bmad has been put to including synchrotron radiation tracking with reflections from the vacuum chamber walls, spin tracking, beam break-up instability, intra-beam scattering, etc. Besides simulation and design programs, Bmad can be used in control programs to do such things as orbit and Twiss correction calculations.  
slides icon Slides WEACI1 [1.884 MB]  
 
WEACC2 Space Charge Effects and Focusing Methods for Laser Accelerated Ion Beams space-charge, solenoid, focusing, laser 184
 
  • P. Schmidt, O. Boine-Frankenheim, V. Kornilov, P. Spädtke
    GSI, Darmstadt, Germany
  
  Funding: GSI Helmholtzzentrum für Schwerionenforschung Planckstr. 1 D-64291 Darmstadt
We employ the 3D PIC simulation code VORPAL to study the transport of laser accelerated proton beams in the framework of the LIGHT project at GSI. Initially the beam is assumed to be neutralized by co-moving electrons. For different initial beam distribution models we study the effect of space charge after the electrons have been removed. The results of the simulations are compared to an envelope model. We derive conditions in terms of the beam parameters and the distance from the production target for a safe removal of the electrons. As an option for the controlled de-neutralization of the beam a thin metallic foil is studied. Besides space charge, we also account for the effect of secondary electrons generated from the foil. 		 
slides icon Slides WEACC2 [0.993 MB]  
 
WEACC3 Matrix Formalism for Long-term Evolution of Charged Particle and Spin Dynamics in Electrostatic Fields lattice, storage-ring, quadrupole, dipole 187
 
  • A.N. Ivanov, S.N. Andrianov
    St. Petersburg State University, St. Petersburg, Russia
  
  The matrix formalism as a numerical approach for solving of ODE equations is considered. It is a map method and has several advantages over classical step-by-step integration methods. This approach allows to present the solution as set of numerical matrices. A complete derivation of the equations this method is based on will be shown. Problems of symplectification and computing performance are discussed. We have developed an application that provides a tool for differential equations solving. The developed program allows to generate the final programming codes on C++, Fortran, MATLAB, C#, Java languages. The given approach is applied to long-term evolution of charged particle and spin dynamics in electrostatic fields.  
slides icon Slides WEACC3 [1.441 MB]  
 
WESCI1 EM Simulations in Beam Coupling Impedance Studies: Some Examples of Application impedance, kicker, resonance, extraction 190
 
  • C. Zannini, G. Rumolo
    CERN, Geneva, Switzerland
  • C. Zannini
    EPFL, Lausanne, Switzerland
  
  In the frame of the SPS upgrade an accurate impedance model is needed in order to predict the instability threshold and if necessary to start a campaign of impedance reduction. Analytical models, 3-D simulations and bench measurements are used to estimate the impedance contribution of the different devices along the machine. Special attention is devoted to the estimation of the impedance contribution of the kicker magnets that are suspected to be the most important impedance source in SPS. In particular a numerical study is carried out to analyze the effect of the serigraphy in the SPS extraction kicker. An important part of the devices simulations are the ferrite model. For this reason a numerical based method to measure the electromagnetic properties of the material has been developed to measure the ferrite properties. A simulation technique, in order to account for external cable is developed. The simulation results were benchmarked with analytical models and observations with beam. A numerical study was also performed to investigate the limits of the wire method for beam coupling impedance measurements.  
slides icon Slides WESCI1 [1.571 MB]  
 
WESCI2 Numerical Calculation of Beam Coupling Impedances in the Frequency Domain using FIT impedance, kicker, space-charge, coupling 193
 
  • U. Niedermayer, O. Boine-Frankenheim
    TEMF, TU Darmstadt, Darmstadt, Germany
  
  The transverse impedance of kicker magnets is considered to be one of the main beam instability sources in the projected SIS-100 at FAIR and also in the SPS at CERN. The longitudinal impedance can contribute to the heat load, which is especially a concern in the cold sections of SIS-100 and LHC. In the high frequency range, commercially available time domain codes like CST Particle Studio® serve to calculate the impedance but they become inapplicable at medium and low frequencies which become more important for larger size synchrotrons. We present the ongoing work of developing a Finite Integration (FIT) solver in frequency domain which is based on the Parallel and Extensible Toolkit for Scientific computing (PETSc) framework in C++. Pre- and post-processing are done in MATLAB®. Infinite beam pipe boundary conditions are used. The code is applied to an inductive insert used to compensate the longitudinal space charge impedance in low energy machines. Another application focuses on the impedance contribution of a ferrite kicker with inductively coupled pulse forming network (PFN) and frequency dependent complex material permeability.  
slides icon Slides WESCI2 [3.468 MB]  
 
WESCI3 Electromagnetic Characterization of Materials for the CLIC Damping Rings damping, impedance, electron, vacuum 198
 
  • E. Koukovini-Platia, G. De Michele, G. Rumolo
    CERN, Geneva, Switzerland
  • C. Zannini
    EPFL, Lausanne, Switzerland
  
  The performance of the Compact Linear Collider (CLIC) damping rings (DR) is likely to be limited by collective effects due to the unprecedented brilliance of the beams. Coating will be used in both electron (EDR) and positron damping rings (PDR) to suppress effects like electron cloud formation or ion instabilities. The impedance modeling of the chambers, necessary for the instabilities studies which will ensure safe operation under nominal conditions, must include the contribution from the coating materials applied for electron cloud mitigation and/or ultra-low vacuum pressure. This advocates for a correct characterization of this impedance in a high frequency range, which is still widely unexplored. The electrical conductivity of the materials in the frequency range of few GHz is determined with the waveguide method, based on a combination of experimental measurements of the complex transmission coefficient S21 and CST 3D electromagnetic (EM) simulations.  
slides icon Slides WESCI3 [2.488 MB]  
 
THAAI1 The Dark Current and Multipacting Capabilities in OPAL: Model, Benchmarks and Applications electron, cyclotron, cavity, gun 201
 
  • C. Wang, Z.G. Yin, T.J. Zhang
    CIAE, Beijing, People's Republic of China
  • A. Adelmann
    PSI, Villigen, Switzerland
  
  Dark current and multiple electron impacts (multipacting), as for example observed in radio frequency (RF) structures of accelerators, are usually harmful to the equipment and the beam quality. These effects need to be suppressed to guarantee stable operation. Large scale simulations can be used to understand the cause and develop strategies to suppress these phenomena. We extend OPAL, a parallel framework for charged particle optics in accelerator structures and beam lines, with the necessary physics models to efficiently and precise simulate multipacting phenomenas. We added a Fowler-Nordheim field emission model, two secondary electron emission models, developed by Furman-Pivi and Vaughan respectively, as well as efficient 3D boundary geometry handling capabilities. The models and their implementation are carefully benchmark against a non-stationary multipacting theory for the classic parallel plate geometry. A dedicated, parallel plate experiment shows excellent agreement between theory, model/simulations and experiment.  
slides icon Slides THAAI1 [6.191 MB]  
 
THAAI2 Efficient Modeling of Laser-plasma Accelerators Using the Ponderomotive-based Code INF&RNO laser, plasma, wakefield, electron 206
 
  • C. Benedetti, E. Esarey, W. Leemans, C.B. Schroeder
    LBNL, Berkeley, California, USA
  
  Funding: Work supported by the Office of Science, Office of High Energy Physics, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Numerical modeling of laser-plasma accelerators using the ponderomotive approximation allows efficient modeling of 10 GeV and beyond laser-plasma accelerators. The time-averaged ponderomotive force approximation also allows simulation in cylindrical geometry which captures relevant 3D physics at 2D computational cost. In this talk I will present the code INF&RNO (INtegrated Fluid & paRticle simulatioN cOde). The code is based on an envelope model for the laser while either a PIC or a fluid description can be used for the plasma. The effect of the laser pulse on the plasma is modeled with the time-averaged poderomotive force. These and other features, such as dynamical resampling of the phase space distribution to reduce on-axis noise and boosted-Lorentz-frame modeling capability, allow for a speedup of several orders of magnitude compared to standard full PIC simulations while still retaining physical fidelity. The code has been benchmarked against analytical solutions and 3D PIC simulations and a set of validation tests together with a discussion of the performances will be presented. Applications to the BELLA PW laser-plasma accelerator experiments at LBNL will be discussed. 		 
slides icon Slides THAAI2 [1.881 MB]  
 
THAAI3 MAD-X Progress and Future Plans lattice, multipole, optics, quadrupole 211
 
  • L. Deniau
    CERN, Geneva, Switzerland
  
  The design efforts for the High Luminosity upgrade of the Large Hadron Collider (HL-LHC) will require significant extensions of the MAD-X code widely used for designing and simulating particle accelerators. These changes are framed into a global redesign of the MAD-X architecture meant to consolidate its structure, increase its robustness and flexibility, and improve its performance. Some examples of recent extensions to MADX like the RF-multipole element will be presented. Improvement for models and algorithms selection providing better consistency of the results and a wider range of use will be discussed. The computation efficiency will also be addressed to better profit of recent technologies. In this paper, we will describe the last improvements and the future plans of the project.  
slides icon Slides THAAI3 [6.830 MB]  
 
THP02 Beam Dynamics Simulations Using GPUs controls, ion, linac, synchrotron 227
 
  • J. Fitzek, S. Appel, O. Boine-Frankenheim
    GSI, Darmstadt, Germany
  
  PATRIC is a particle tracking code used at GSI to study collective effects in the FAIR synchrotrons. Due to the need for calculation-intense simulations, parallel programming methods are being explored to optimize calculation performance. Presently the tracking part of the code is parallelized using MPI, where each node represents one slice of the particles that travel through the accelerator. In this contribution different strategies will be presented to additionally employ GPUs in PATRIC and exploit their support for data parallelism without major code modifications to the original tracking code. Some consequences of using only single-precision in beam dynamics simulations will be discussed.  
 
THP07 Some Computational Challenges in the Modeling of Accelerators and their Solutions in the Simulation Code Warp laser, plasma, acceleration, electron 233
 
  • J.-L. Vay, C. Benedetti
    LBNL, Berkeley, California, USA
  • R.H. Cohen, A. Friedman, D.P. Grote
    LLNL, Livermore, California, USA
  
  Funding: Supported by US-DOE Contracts DE-AC02-05CH11231 and DE-AC52-07NA27344, and the SciDAC/ComPASS project. Used resources of NERSC, supported by US-DOE Contract DE-AC02-05CH11231.
The Particle-In-Cell Code-Framework Warp originated in the Heavy Ion Fusion program to guide the development of accelerators that can deliver beams suitable for implosion of inertial fusion capsules. The range of application of Warp has considerably widened far beyond the initial area and it is now applied to the study and design of existing and next-generation high-energy accelerators, including, for example, the study of laser wakefield acceleration and electron cloud effects. We present an overview of Warp's capabilities, summarizing recent original numerical methods that were developed to address computational challenges such as space and time scale disparities, spurious numerical dispersion, efficient wideband digital filtering on parallel platforms, etc. The original methods include simulations in Lorentz boosted frames, an electromagnetic solver with tunable numerical dispersion and efficient stride-based digital filtering, Particle-In-Cell with Adaptive Mesh Refinement, a large-timestep ‘‘drift-Lorentz'' mover for arbitrarily magnetized species, and a relativistic Lorentz invariant leapfrog particle pusher. Selected examples of applications will be given. 		 
 
THP08 Beam Dynamics Studies for Particle Driven Plasma Wakefield Acceleration Experiments at PITZ plasma, electron, laser, focusing 236
 
  • M. Khojoyan, M. Groß, G. Klemz, G. Koss, M. Krasilnikov, A. Oppelt, F. Stephan
    DESY Zeuthen, Zeuthen, Germany
  • M. Khojoyan
    ANSL, Yerevan, Armenia
  
  The Photo Injector Test Facility at DESY, Zeuthen site (PITZ) is developing and optimizing high brightness electron sources for linac based free electron lasers such as FLASH and the European XFEL. The high quality of the 25 MeV electron beam together with the availability of a highly flexible photocathode laser system makes the PITZ injector a perfect facility for variety of experimental studies. Two approaches are of great interest for future applications in the context of particle driven plasma wakefield acceleration experiments: self-modulation and transformer ratio studies. In both cases a high density electron beam is interacting with a plasma which has a density of about 1015 cm-3. ASTRA simulations were done to study the e-beam density along the existing PITZ beamline, especially at two different possible longitudinal positions of the planned plasma cell, in order to reach the particle density required for occurrence of self-modulation. The results of the beam dynamics studies are presented and discussed in this paper.  
 
THP13 Emission Studies of Photocathode RF Gun at PITZ gun, electron, cathode, space-charge 242
 
  • J. Li, G. Asova, M. Groß, L. Hakobyan, I.I. Isaev, Ye. Ivanisenko, M. Khojoyan, G. Klemz, G. Kourkafas, M. Krasilnikov, K. Kusoljariyakul, M. Mahgoub, D. Malyutin, B. Marchetti, A. Oppelt, B. Petrosyan, S. Rimjaem, A. Shapovalov, F. Stephan, G. Vashchenko
    DESY Zeuthen, Zeuthen, Germany
  • G. Feng
    DESY, Hamburg, Germany
  • D. Richter
    HZB, Berlin, Germany
  • L. Shang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  The Photo Injector Test facility at DESY, Zeuthen site (PITZ), was built to develop and optimize electron sources for linac based Free Electron Lasers(FELs) like FLASH and the European XFEL. For the value of the bunch charge extracted from a photocathode, discrepancy has been observed between the data measured at PITZ and simulation results from the ASTRA code. As a factor which could explain the discrepancy, a Schottky-like effect is considered. Meanwhile, the Parmela code was applied to the emission studies on the PITZ gun as benchmark. Since Parmela cannot be used to simulate a Schottky-like effect with its own modules, MATLAB scripts have been developed to implement this feature of the photoemission in an RF gun.  
 
THACC3 Preliminary Study of Single Spike SASE FEL Operation at 0.26 Nanometers Wavelength for the European XFEL electron, radiation, laser, FEL 253
 
  • B. Marchetti, M. Krasilnikov, F. Stephan
    DESY Zeuthen, Zeuthen, Germany
  • M. Dohlus, Y.A. Kot, I. Zagorodnov
    DESY, Hamburg, Germany
  • J. Rönsch-Schulenburg
    Uni HH, Hamburg, Germany
  
  The production of ultra-short (fs or sub-fs long), high power, radiation pulses in the X-ray spectral region, showing a single spike spectrum, represents a challenge for many existent SASE- FELs [1, 2]. In order to realize single spike operation the length of the electron bunch after compression must be extremely small [3] (less than a micrometer) and the consequent degradation of its emittance has not to suppress the radiation production. Several technical restrictions, such as limits of diagnostics for small charges, RF jitter and micro-bunching instabilities play an important role in the choice of the operation working point. In this paper we are going to study the feasibility of single spike or few spikes lasing for bunches with charge of tens of pC in the European XFEL facility giving some preliminary results concerning the choice of the working point.
[1] J.B. Rosenzweig et al., NIM A 593 (2008) 39-44
[2] S. Reiche et al., NIM A 593 (2008) 45-48
[3] R. Bonifacio et al., PRL vol. 73 n.1 (1994)
 		 
slides icon Slides THACC3 [1.401 MB]  
 
THSDI2 Simulation of Multibunch Instabilities with the HEADTAIL Code impedance, octupole, wakefield, synchrotron 262
 
  • N. Mounet, E. Métral, G. Rumolo
    CERN, Geneva, Switzerland
  
  Multibunch instabilities due to beam-coupling impedance can be a critical limitation for synchrotrons operating with many bunches. To study these instabilities, the HEADTAIL code has been extended to simulate the motion of many bunches under the action of wake fields. All the features already present in the single-bunch version of the code have remained available, in particular synchrotron motion, chromaticity, amplitude detuning due to octupoles and the ability to load any kind of wake fields through tables. The code has been then parallelized in order to track thousands of bunches in a reasonable amount of time, showing a linear scaling with the number of processors used. We show benchmarks against Laclare's theory in simple cases, obtaining a good agreement. Results for bunch trains in the LHC and comparison with beam-based measurements are also exhibited.  
slides icon Slides THSDI2 [7.278 MB]  
 
THSDC3 Calculation of Longitudinal Instability Threshold Currents for Single Bunches synchrotron, damping, cavity, shielding 267
 
  • P. Kuske
    HZB, Berlin, Germany
  
  Based on the publication by M. Venturini, et al.[1] a computer program has been written that solves the Vlasov-Fokker-Planck equation numerically on a two dimensional grid. In this code different types of longitudinal interactions and their combinations are implemented like the shielded CSR- as well as the purely resistive and inductive interactions of the electrons within the bunch. The details of the program will be presented in the paper. Calculations have been performed for the 1.7 GeV storage ring BESSY II and the 600 MeV ring MLS. The results are compared with measurements on both rings which were based on the observation of the onset of bursts of coherent synchrotron radiation. Fair agreement is found between theoretical and experimental observations. The theoretical results complement calculations performed by Bane, et al. for the shielded CSR-interaction [2]. The new results emphasize the resistive nature of the CSR-Interaction, especially in regions where shielding effects are small.
[1] M. Venturini, et al., Phys. Rev. ST-SB, 8, 014202(2005)
[2] K.L.F. Bane, et al., “Comparison of Simulation Codes for Microwave Instability in Bunched Beams“, IPAC 2010, Kyoto, Japan
 		 
slides icon Slides THSDC3 [1.006 MB]  
 
FRAAI1 Computational Needs for RF Design of Superconducting Cavities cavity, HOM, SRF, linac 270
 
  • A. Lunin, T.N. Khabiboulline, V.P. Yakovlev
    Fermilab, Batavia, USA
  
  Funding: Operated by Fermi Research Alliance, LLC under Contract No.DE-AC02-07CH11359 with the U.S. Department of Energy.
The computational approaches assure essential guidance and order for the design of a superconducting cavities and cryomodules. The nature of superconductivity requires precise surface electromagnetic fields computation in order to design the cavity shape with a maximum accelerating gradient. At the same time the thickness of the cavity shell is limited by the ability to cool it down the temperature of liquid He, which makes the mechanical stability of the cavity and liquid He vessel assembly extremely important. Hence, it demands a self consistent electro-mechanical optimization in order to minimize microphonics and/or Lorentz force detuning phenomena. Specific challenges are an estimation of RF losses caused by the interaction of the passing beam with SC cavity and a multipactor analysis in the SC cavity and RF coupler. Finally the irregular time structure of a beam train with its own dense spectra may stochastically induce HOM fields in a cavity which results the beam emittance dilution. The study of these effects leads to specifications of SC cavity and cryomodule and can significantly impact on the efficiency and reliability of the superconducting linac operation. 		 
slides icon Slides FRAAI1 [8.162 MB]  
 
FRAAC2 Arbitrary High-Order Discontinuous Galerkin Method for Electromagnetic Field Problems electromagnetic-fields, higher-order-mode, cavity, coupling 275
 
  • K. Papke, C.R. Bahls, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  
  Funding: Work supported by Federal Ministry for Research and Education BMBF under contract 05K10HRC
For the design and optimization of Higher-Order-Mode Coupler, used in RF accelerator structures, numerical computations of electromagnetic fields as well as scattering parameter are essential. These computations can be carried out in time domain. In this work the implementation and investigation of a time integration scheme, using the Arbitrary high-order DERivatives (ADER) approach, applied on the Discontinuous Galerkin finite-element method (DG-FEM) is demonstrated for solving 3-D electromagnetic problems in time domain. This scheme combines the advantage of high accuracy with the possibility of an efficient implementation as local time stepping scheme, which reduces the calculation time for special applications considerable. It is implemented in NUDG++*, a framework written in C++ that deals with the DG-FEM for spatial discretization of the Maxwell equations. Accuracy and performance is analyzed by a suitable benchmark.
* Nodal Unstructured Discontinuous Galerkin in C++ 		 
slides icon Slides FRAAC2 [6.767 MB]  
 
FRSAC1 Hybrid Programming and Performance for Beam Propagation Modeling wakefield, undulator, cavity 284
 
  • M. Min, A. Mametjanov
    ANL, Argonne, USA
  • J. Fu
    RPI, Troy, New York, USA
  
  Funding: DOE ASCR (Advanced Scientific Computing Research) Program
We examined hybrid parallel infrastructures in order to ensure performance and scalability for beam propagation modeling as we move toward extreme-scale systems. Using an MPI programming interface for parallel algorithms, we expanded the capability of our existing electromagnetic solver to a hybrid (MPI/shared-memory) model that can potentially use the computer resources on future-generation computing architecture more efficiently. As a preliminary step, we discuss a hybrid MPI/OpenMP model and demonstrate performance and analysis on the leadership-class computing systems such as the IBM BG/P, BG/Q, and Cray XK6. Our hybrid MPI/OpenMP model achieves speedup when the computation amounts are large enough to compensate the OMP threading overhead. 		 
slides icon Slides FRSAC1 [4.252 MB]  
 
FRSAC2 Comparison of Eigenvalue Solvers for Large Sparse Matrix Pencils cavity, target, electromagnetic-fields, superconducting-cavity 287
 
  • F. Yaman, W. Ackermann, T. Weiland
    TEMF, TU Darmstadt, Darmstadt, Germany
  
  Funding: Work supported by the DFG through SFB 634
Efficient and accurate computation of eigenvalues and eigenvectors is of fundamental importance in the accelerator physics community. Moreover, the eigensystem analysis is generally used for the identifications of many physical phenomena connected to vibrations. Therefore, various types of algorithms such that Arnoldi, Lanczos, Krylov-Schur, Jacobi-Davidson etc. were implemented to solve the eigenvalue problem efficiently. In this direction, we investigate the performance of selected commercial and freely available software tools for the solution of a generalized eigenvalue problem. We choose two setups by considering spherical and billiard resonators in order to test the robustness, accuracy, and computational speed and memory consumption issues of the recent versions of CST, Matlab, Pysparse, SLEPc and CEM3D. Simulations were performed on a standard personal computer as well as on a cluster computer to enable the handling of large sparse matrices in the order of hundreds of thousands up to several millions degrees of freedom. We obtain interesting comparison results with the examined solvers which is useful for choosing the appropriate solvers for a given practical application. 		 
slides icon Slides FRSAC2 [10.095 MB]  
 
FRSAI3 PIC Simulations of Laser Ion Acceleration via TNSA electron, laser, proton, plasma 290
 
  • L. Lecz
    TEMF, TU Darmstadt, Darmstadt, Germany
  • O. Boine-Frankenheim, V. Kornilov
    GSI, Darmstadt, Germany
  
  The laser acceleration of protons via the TNSA (Target Normal Sheath Acceleration) mechanism from a thin metal foil (few micrometer) interacting with intense and short (several 100 fs) laser pulse is investigated by using 1D and 2D particle-in-cell electro-magnetic VORPAL [1] simulations. The protons originate from the very thin hydrogen-rich contamination layer on the target rear surface. In the 1D view we have found that two models well describe the longitudinal acceleration in the two extreme cases: quasi-static acceleration [2] for mono-layers and isothermal plasma expansion [3] for thick layers. The grid heating, which is the most important issue in 2D simulations, and its effect on the proton acceleration is discussed. The required numerical parameters and boundary conditions for stable and reliable 2D simulations are also presented.
[1] http://www.txcorp.com/products/VORPAL/
[2] M. Passoni et al., Phys Rev E 69, 026411 (2004)
[3] P. Mora, Phys. Rev. Lett., 90, 185002 (2003) 		 
slides icon Slides FRSAI3 [4.325 MB]  
 
FRABI2 Big Data Analysis and Visualization: What Do Linacs and Tropical Cyclones Have in Common? plasma, linac, laser, electron 299
 
  • E.W. Bethel, S. Byna, J. Chou, E. Cormier-Michel, C.G.R. Geddes, M. Howison, F. Li, P. Prabhat, J. Qiang, O. Rübel, R.D. Ryne, M.F. Wehner, K. Wu
    LBNL, Berkeley, California, USA
  
  Funding: This work was supported by the Director, Office of Science, Office and Advanced Scientific Computing Research, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
While there is wisdom in the old adage "the two constants in life are death and taxes," there are unavoidable truths facing modern experimental and computational science. First is the growing "impedence mismatch" between our ability to collect and generate data, and our ability to store, manage, and gain understanding from it. The second is the fact that we cannot continue to rely on the same software technologies that have worked well for the past couple of decades for data management, analysis, and visualization. A third is that these complementary activities must be considered in a holistic, rather than balkanized way. The inseperable interplay between data management, analysis, visualization, and high performance computational infrastructure, are best viewed through the lens of case studies from multiple scientific domains, where teams of computer and accelerator scientists combine forces to tackle challenging data understanding problems. 		 
slides icon Slides FRABI2 [3.622 MB]