05 Beam Dynamics and Electromagnetic Fields
D06 Code Developments and Simulation Techniques
Paper Title Page
TUXB01 Methods and Tools to Simulate and Analyse Non-linear Dynamics in Electron Storage Rings 937
 
  • L.S. Nadolski
    SOLEIL, Gif-sur-Yvette, France
 
  This talk will present the different approaches and tools that have been recently developed while trying to understand or predict the non-linear dynamics of electron storage rings. Different algorithms have been recently used at different places to optimize the sextupole tunings, while the refinement of the models of existing machines together with more accurate measurement techniques enable now to fully understand the limitations of such facilities specially in the presence of insertion devices.  
slides icon Slides TUXB01 [7.624 MB]  
 
TUOAB03 Enlarging Dynamic and Momentum Aperture by Particle Swarm Optimization 948
 
  • Z. Bai, W. Li, L. Wang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  Particle swarm optimization (PSO) is a computational intelligence algorithm for global optimization. Obtaining adequate dynamic and momentum aperture is crucial for high injection efficiency and long beam lifetime in low emittance electron storage rings. Different from nonlinear driving terms optimization, we have made direct optimization of dynamic and momentum aperture by PSO algorithm. It is critical to make a criterion for comparison of dynamic and momentum aperture tracking results in the direct optimization procedure. Thus, in this paper we first propose a quantitative criterion of dynamic aperture. Then we apply PSO to the optimization of chromatic and harmonic sextupoles to find the optimum sextupole settings for enlarging the dynamic aperture. Taking the momentum aperture into consideration, we make joint optimization of dynamic and momentum aperture. Also, the momentum aperture has its quantitative criterion. As an example of application, the dynamic and momentum aperture of an FBA lattice studied in the design of storage ring of Hefei Advanced Light Source were optimized, and the results have shown the power of PSO algorithm.  
slides icon Slides TUOAB03 [0.313 MB]  
 
WEPC079 Beta-beating in the Effective Model of the LHC Using PTC 2202
 
  • M.C. Alabau Pons, F. Schmidt, R. Tomás
    CERN, Geneva, Switzerland
  • E.H. Maclean
    JAI, Oxford, United Kingdom
 
  An effective model of the LHC optics has been developed based on measurements of magnetic field, alignment errors and closed orbit. This model utilizes the Polymorphic Tracking Code with MAD-X as front-end to allow the inclusion of harmonics to an arbitrary order in thick lattice elements. Beta-beating calculations have been performed with this model at injection optics and at 3.5 TeV squeezed optics to 3.5 m beta-function at the interaction point. The model predictions are in remarkable agreement with the measurements performed in the 2010 LHC commissioning run.  
 
WEPC088 Embedding Finite Element Results for Accelerator Components in a Moment Approach Beam Dynamics Code* 2217
 
  • 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''.
A moment based beam dynamics code has particular advantages, i.e. accuracy and efficiency, over macro-particle tracking and full particle-in-cell (PIC) codes respectively. Instead of embedding analytical descriptions of the accelerator components in the beam dynamics model, it is proposed to insert a surrogate model obtained from the finite element model of individual accelerator components. We apply the V-Code, which accepts moments up to the sixth order and accounts for space charge effects. We construct and calculate finite element and finite difference time domain models using the CST Studio Suite 2011 software package. An interface is implemented using VBA and MATLAB. As an example of the accuracy of this cascadic simulation approach, we compare the beam dynamics of an S-DALINAC quadrupole obtained by directly tracking particles to the calculated fields with the results for the cascadic approach with the V-Code.
This work was performed during a three month research visit at the Technische Universität Darmstadt, Institut für Theorie Elektromagnetischer Felder, Darmstadt, Germany.
 
 
WEPC091 Studies with a Particle Tracking Code for the SIS100 Resonant Extraction System 2220
 
  • M.M. Kirk, G. Franchetti, H. Klingbeil, P. Moritz, N. Pyka, H. Ramakers, P.J. Spiller, H. Welker
    GSI, Darmstadt, Germany
 
  Several issues concerning the envisaged SIS100 resonant extraction at GSI can be resolved with a simulation-lead approach for which a particle tracking code was developed. Applications to date have included: design and testing of data supply algorithms for the accelerator control system; requirements analysis for the power converter ripple in the quadrupoles forming the doublet focusing; and verification of the RF Knock-Out exciter's performance.  
 
WEPC092 Moment-Based Simulation of the S-DALINAC Recirculations* 2223
 
  • S. Franke, W. Ackermann, T. Weiland
    TEMF, TU Darmstadt, Darmstadt, Germany
  • R. Eichhorn, F. Hug, C. Klose, N. Pietralla, M. Platz
    TU Darmstadt, Darmstadt, Germany
 
  Funding: Work supported by DFG under contract SFB 634.
The Superconducting Linear Accelerator S-DALINAC installed at the institute of nuclear physics (IKP) at TU Darmstadt is designed as a re-circulating linear accelerator. The length of the beam line and the numerous accelerating structures as well as dipole and quadrupole magnets require a highly efficient numerical simulation tool in order to assist the operators by providing a detailed and almost instantaneous insight into the actual machine status. A suitable approach which enables a fast online calculation of the beam dynamics is given by the so-called moment approach where the particle distribution is represented by means of a discrete set of moments or by multiple discrete sets of moments in a multi-ensemble environment. Following this approach the V-Code simulation tool has been implemented at the Computational Electromagnetics Laboratory (TEMF) at TU Darmstadt. In this contribution an overview of the numerical model is presented together with new V-Code simulation results regarding the S-DALINAC recirculation sections.
 
 
WEPC093 Various Approaches to Electromagnetic Field Simulations for RF Cavities 2226
 
  • C. Liu, W. Ackermann, W.F.O. Müller, T. Weiland
    TEMF, TU Darmstadt, Darmstadt, Germany
 
  Funding: Work supported by BMBF under contract 05H09RD5
In the Superconducting Proton Linac (SPL) cavity, there is not only the fundamental mode for the particle acceleration but also many higher order modes (HOMs), which can lead to particle beam instabilities. This is very dangerous for SPL cavity. Therefore it is necessary to simulate the electromagnetic field in the SPL cavity, so that the field distribution and the shunt impedance for every higher order mode can be precisely calculated. At TEMF this research work can be done in three different ways: field simulation with hexahedron mesh in frequency domain, field simulation with hexahedron mesh in time domain and field simulation with tetrahedral mesh and higher order curvilinear elements. Finally the HOM coupler will be considered for the effective damping of higher order modes in the SPL cavity.
 
 
WEPC094 Energy Loss and Longitudinal Wakefield of Relativistic Short Ion Bunches in Electron Clouds 2229
 
  • F. Yaman, O. Boine-Frankenheim, E. Gjonaj, T. Weiland
    TEMF, TU Darmstadt, Darmstadt, Germany
  • G. Rumolo
    CERN, Geneva, Switzerland
 
  Funding: Work supported by BMBF under contract 06DA9022I
The aim of our study is the numerical computation of the wakefield, impedance and energy loss for an energetic, short (< 10 ns) ion bunch penetrating an electron cloud plasma residing in the beam pipe. We use a 3-D self-consistent and higher order PIC code based on the full-wave solution of the Maxwell equations in the time domain. In our simulations we observe the induced density oscillations in the electron cloud in the longitudinal as well as in the transverse directions. A special numerical procedure is applied to compute the longitudinal wake potential and the broadband coupling impedance due to the beam-electron cloud interaction. The code is applied to the case of the CERN SPS and the projected SIS-100 at GSI. The effects of the beam pipe, electron density, bunch intensity and external magnetic dipole fields are studied. The results are compared to analytical and numerical models of reduced complexity.
 
 
WEPC095 Simulations of the Microbunching Instability at ANKA using a Vlasov-Fokker-Planck Solver 2232
 
  • M. Klein, A.-S. Müller
    KIT, Karlsruhe, Germany
  • K.G. Sonnad
    CLASSE, Ithaca, New York, USA
 
  In order to produce coherent synchrotron radiation the ANKA light source is operated frequently in short bunch mode. It is known that during this procedure strong self fields caused by high electron densities can enforce initial density fluctuations and thus lead to microbunching. The build-up of those substructures is accompanied by bursting radiation which provides higher radiation power for the users. Damping and diffusion due to incoherent radiation smoothens the bunch shape again and hence lead to periodic or chaotic bursting cycles. The evolution of the electron bunch density under the influence of self fields can be described by the Vlasov-Fokker-Plank (VFP) equation. We present results from a numerical solution of the VFP-equation for parameters used in standard short bunch mode at ANKA.  
 
WEPC096 Calculation of High Frequency Fields in Resonant Cavities Based on Perturbation Theory* 2235
 
  • K. Brackebusch, H.-W. Glock, 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.
The knowledge of the eigenmodes of resonant accelerator cavities is essential for the determination of their performance characteristics, comprising resonant frequencies and field distributions inside the cavities. Apart from the material properties the eigenmodes of a cavity depend on its geometry. In spite of the high elaborateness during the complex fabrication process, minor deviations of the actual cavity shape from the desired one are inevitable. Moreover, especially superconducting cavities are subject to extreme operating conditions that may cause deformations of their shape. Any geometry perturbation results in a shift of the resonant frequencies and modified field distributions. In this paper, we will analyze a generalization of Slater's theorem proposed in literature. The method should allow for the calculation of resonant frequencies and field distributions of a slightly perturbed cavity by using a set of precomputed eigenmodes of the unperturbed cavity. We will evaluate the practicability of the method by applying it to cavity geometries for which the eigenmodes are analytically known, ascertain the effort of reasonable calculation results and describe its limitations.
 
 
WEPC097 A Concatenation Scheme for the Computation of Beam Excited Higher Order Mode Port Signals 2238
 
  • T. Flisgen, H.-W. Glock, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
 
  Ongoing studies investigate in how far higher order mode (HOM) port signals of superconducting RF cavities can be used for machine and beam diagnostics. Apart from experiments e.g. at the FLASH facility at DESY in Hamburg, numerical modelling is needed for the prediction of HOM coupler signals. For this purpose, the RF properties of the entire accelerating module have to be taken into account, since higher order modes can propagate along the cavity chain. A discretization of the full chain, followed by a wake field simulation is only feasible with powerful and expensive cluster computers. Instead, an element wise wake field simulation of sub-sections of the chain, followed by a suitable concatenation scheme can be performed on standard hardware assuming the beam to be sufficiently stiff. In this paper a concatenation scheme for the computation of beam excited HOM port signals is derived as a generalization of the Coupled S-Parameter scheme CSC. Furthermore, the validity of the method is shown for a sample structure.  
 
WEPC098 Automatic Pole and Q-Value Extraction for RF Structures 2241
 
  • C. Potratz, H.-W. Glock, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • F. Marhauser
    JLAB, Newport News, Virginia, USA
 
  The experimental characterization of RF structures like accelerating cavities often demands for measuring resonant frequencies of Eigenmodes and corresponding (loaded) Q-values over a wide spectral range. A common procedure to determine the Q-values is the -3dB method, which works well for isolated poles, but may not be applicable directly in case of multiple poles residing in close proximity (e.g. for adjacent transverse modes differing by polarization). Although alternative methods may be used in such cases, this often comes at the expense of inherent systematic errors. We have developed an automation algorithm, which not only speeds up the measurement time significantly, but is also able to extract Eigenfrequencies and Q-values both for well isolated and overlapping poles. At the same time the measurement accuracy may be improved as a major benefit. To utilize this procedure merely complex scattering parameters have to be recorded for the spectral range of interest. In this paper we present the proposed algorithm applied to experimental data recorded for superconducting higher-order-mode damped multi-cell cavities as an application of high importance.  
 
WEPC099 Coupler Design and Optimization by GPU-Accelerated DG-FEM 2244
 
  • C. Potratz, H.-W. Glock, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
 
  The numerical optimization of rf-components like couplers is a common task during the design phase of particle accelerators. Typically, these optimizations involve the simulation of a multitude of very similar structures with minor geometric variations. Nevertheless, this process is in its entire extend rather demanding on both the invested time and hardware budget. With recent advancements in the field of numerical electromagnetic field simulation and consumer graphic processors, an interesting alternative for the time-consuming simulation part of the optimization is available. In this contribution we show, how the Discontinuous Galerkin FEM method in conjunction with consumer graphic cards can be used to build moderately prized cluster solutions for the parallel simulation of rf-components. The contribution will mainly focus on, but is not limited to, Higher Order Mode couplers as a typical application example, where the DG-FEM method accelerated by a graphic processor might be used to significantly reduce the overall time necessary for the optimization.  
 
WEPC100 Simulation of the Single Bunch Instability due to the Electron Cloud Effect by Tracking with a Pre-computed 2D Wake Matrix* 2247
 
  • A. Markoviḱ, G. Pöplau, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
 
  Funding: Supported by DFG Contract Nr. RI 814/20-1.
The passage of a positron bunch through an initially homogeneous electron cloud (e-cloud) changes the distribution of the e-cloud in a way that the concentration of electrons in the proximity of the beam axis grows rapidly. The electrons are primarily moving in the transverse plane and are very sensitive on the beam centroid position in that plane. Thus the transverse kick of the e-cloud on the tail particles depends on the centroid position of the head particles of the same bunch. A PIC simulation of the interaction of a positron beam with an e-cloud yields the wake kick from the electrons on the tail particles for a certain offset in the transverse centroid position of the head parts of the bunch. With such a pre-computed 2D wake matrix, for a certain e-cloud density, we investigate the stability of a single bunch by tracking it through the linear optics of the storage ring while at each turn applying the kick from the e-cloud. We examine the positron bunch stability of KEKB-LER and PETRAIII for a certain electron cloud density.
 
 
WEPC101 Simulation of the Interaction of an Electron Beam with Ionized Residual Gas 2250
 
  • G. Pöplau, 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 number 05K10HRC
Light sources of the next generation such as ERLs require minimal beam losses as well as a stable beam position and emittance over the time. Instabilities caused by ion accumulation have to be avoided. In Rostock the tracking code MOEVE PIC Tracking has been developed for the simulation of space charge influenced beam dynamics, which is recently applied for simulations of the interaction beam - e-cloud. In this paper we apply MOEVE PIC Tracking for simulation of the interaction of the ionized residual gas with an electron bunch. We demonstrate numerical results with parameters planed for the ERL BERLinPro.
 
 
WEPC102 Recent Developments for Efficient 3D Space Charge Computations Based on Adaptive Multigrid Discretizations 2253
 
  • G. Pöplau, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • M.J. de Loos
    TUE, Eindhoven, The Netherlands
  • S.B. van der Geer
    Pulsar Physics, Eindhoven, The Netherlands
 
  Funding: Partly supported by BMBF under contract number 05K10HRC
Efficient and accurate space-charge computations are essential for the design of high-brightness charged particle sources. Recently a new adaptive meshing strategy based on multigrid was implemented in GPT and the capabilities were demonstrated. This new meshing scheme uses the solution of an intermediate step in the multigrid algorithm itself to define optimal mesh line positions. In this paper we discuss further developments of this adaptive meshing strategy. We compare the new algorithm with the current meshing scheme of GPT, where the mesh line positions are based upon the projected charge density.
 
 
WEPC104 Vicky : A Computer Code for Use in the Design and Simulation of Particle Accelerators 2256
 
  • F. Iazzourene
    ELETTRA, Basovizza, Italy
 
  Vicky is a computer code under development for designing and simulating particle accelerators. Like other existing codes, the features include machine imperfections, closed orbit correction, Twiss functions matching, chromaticity evaluation and correction, particle tracking and so on. The goal is to give the users a friendly graphical interface with widgets to perform the wished tasks, for example to plot the orbit, the Twiss functions, the tune diagram, the dynamic aperture and so on, to select and read an input file describing the considered lattice, to perform the Twiss functions matching, a closed orbit correction and so on. The code provides a description of the particle motion by 10 parameters: four beta-functions, four alpha-functions and two phase advances, that is a 4*4 generalized transverse coupling, together with an emphasis on the treatment of the complex 3D magnetic fields of the undulators used in today’s modern synchrotron radiation facilities. The code is written in C++. It uses the free packages QT for the online plots and the graphical user interface and IT++ for the mathematics. The present status and some results of its application will be presented.  
 
WEPC105 Multiparticle Simulation of Intrabeam Scattering for SuperB 2259
 
  • T. Demma, M.E. Biagini, M. Boscolo
    INFN/LNF, Frascati (Roma), Italy
  • K.L.F. Bane, A. Chao, M.T.F. Pivi
    SLAC, Menlo Park, California, USA
 
  Intrabeam scattering (IBS) is associated with multiple small angle scattering events leading to emittance growth. In most electron storage rings, the growth rates arising from IBS are much longer than damping times due to synchrotron radiation, and the effect on emittance growth is negligible. However, IBS growth rates increase with increasing bunch charge density, and for storage rings such as SuperB, that operate with high bunch charges and very low vertical emittance, the IBS growth rates can be large enough to produce significant emittance increase. Several formalisms have been developed for calculating IBS growth rates in storage rings*. However these models, based on Gaussian bunch distributions, cannot investigate some interesting aspects of IBS such as its evolution during the damping process and its effect on the beam distribution. We developed a multiparticle tracking code, based on the Binary Collision Model**, to investigate these effects. In this communication we present the structure of the code and simulation results obtained with particular reference to the SuperB parameters. Simulation results are compared with those of conventional IBS theories.
* A. Piwinski, Lect. Notes Phys. 296 (1988); J.D. Bjorken and S.K. Mtingwa, Part. Accel. 13 (1983); K. Kubo et al., Phys. Rev. ST-AB 8 (2005).
** Peicheng Yu et al., Phys. Rev. ST–AB 12 (2009).
 
 
WEPC106 Touschek Effect at DAΦNE for the New KLOE Run in the Crab-Waist Scheme 2262
 
  • M. Boscolo, P. Raimondi
    INFN/LNF, Frascati (Roma), Italy
  • E. Paoloni
    University of Pisa and INFN, Pisa, Italy
  • A. Perez
    INFN-Pisa, Pisa, Italy
 
  Funding: Work supported by the EuCARD research programme within the 'Assessment of Novel Accelerator Concepts' work package (ANAC-WP11)
The innovative crab-waist collision scheme has been recently implemented at DAΦNE for a new KLOE run. This scheme requires special attention to the Touschek effect, both for the lifetime and the machine induced backgrounds into the detector. These two aspects have been handled starting from the same Monte Carlo simulation. The DAΦNE optical model has been tuned to keep the effects of Touschek scattering under control with a trade-off between critical parameters, following the indications given by simulations. Connections between numerical results and lattice modifications are discussed here. Dedicated lifetime measurements have been carried out to validate these studies. Particle losses at the IR have been minimized by means of the same optical knobs, but in addition proper shieldings have been implemented to further decrease their impact on the detector performance. IR distributions of the Touschek particle losses have been tracked from the beam pipe into KLOE for direct comparison of measured and expected backgrounds. Moreover, these studies are carried out with the same software tools used for the SuperB factory design, allowing a direct validation test of this approach.
 
 
WEPC107 Development of a Steady State Simulation Code for Klystron Amplifiers 2265
 
  • C. Marrelli
    CERN, Geneva, Switzerland
  • M. Migliorati, A. Mostacci, L. Palumbo
    Rome University La Sapienza, Roma, Italy
  • B. Spataro
    INFN/LNF, Frascati (Roma), Italy
  • S.G. Tantawi
    SLAC, Menlo Park, California, USA
 
  The design of klystrons is based on the intensive utilization of simulation codes, which can evaluate the complete beam-cavities interaction in the case of large signals. In the present work, we present the development of a 2-D steady state simulation code that can self-consistently evaluate the effects of the electromagnetic field on the particles and of the particles back on the field. The algorithm is based on the iterative solution of the power balance equation in the RF structures and allows determining the amplitude and phase of the electromagnetic field starting from the cavity modes. Some applications of the code to a single cavity and a two cavity klystron are presented and compared with the results obtained from other codes. The effect of the space charge forces in the klystron drift tubes is also evaluated.  
 
WEPC108 CSR Impedance for an Ultrarelativistic Beam moving in a Curved Trajectory 2268
 
  • D.M. Zhou, K. Ohmi, K. Oide
    KEK, Ibaraki, Japan
 
  A dedicated computer code, CSRZ, has been developed to calculate the coherent synchrotron radiation (CSR) impedance for an ultrarelativistic beam moving in a curved trajectory. Following the pioneering work of T. Agoh and K. Yokoya*, the code solves the parabolic equation in the frequency domain in a curvilinear coordinate system. The beam is assumed to move along a vacuum chamber which has a uniform rectangular cross section but with variable bending radius. Using this code, we did investigations in calculating the longitudinal CSR impedance of a single and a series of bending magnets. The calculation results indicate that the shielding effect due to outer chamber wall can be well explained by a simple optical approximation model at high frequencies. The CSR fields reflected by the outer wall may interfere with each other in a long bending magnet and lead to sharp narrow peaks in the CSR impedance.
* T. Agoh and K. Yokoya, Phys. Rev. ST Accel. Beams, 7(5):054403 (2004).
 
 
WEPC109 Emittance Optimization Using Particle Swarm Algorithm* 2271
 
  • Z. Bai, W. Li, L. Wang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  In this paper we use a swarm intelligence algorithm, particle swarm optimization (PSO), to optimize the emittance directly. Some constraint conditions such as beta functions, fractional tunes and dispersion function, are considered in the emittance optimization. We optimize the strengths and positions of quadrupoles to search low emittances. Here an FBA lattice studied in the design of the Hefei Advanced Light Source storage ring is used as the testing lattice. The PSO is shown to be beneficial in the optimization.  
 
WEPC111 Single Particle Tracking Simulation for Compact Cyclotron* 2274
 
  • H.W. Kim, J.-S. Chai, B.N. Lee, Y.S. Lee, K.R. Nam, H.S. Song
    SKKU, Suwon, Republic of Korea
 
  Funding: Ministry of Education, Science and Technology, Republic of Korea. Department of Energy Science and School of Information and Communication Engineering of SungKyunKwan University.
Low energy compact cyclotrons for Positron emission tomography (PET) are needed for the production of radio-isotope. In the magnet design for those cyclotrons, single particle tracking simulation after the design is important to check the quality of designed magnetic field of the magnet. The study of single particle tracking simulation for cyclotron magnet is shown in this paper. Maximum beam energy of example cyclotron is 9 MeV for proton and pseudo accelerating gap is adapted for the simulation. 3D CAD program CATIA P3 V5 R18 is used for design the magnet and pseudo accelerating gap. All magnetic and electric field calculations had been performed by OPERA-3D TOSCA and the own-made program OPTICY is used for other calculations - phase slip, radial and axial tune.
 
 
WEPC114 Covariant Formulation of the Vlasov Equation 2277
 
  • O.I. Drivotin
    St. Petersburg State University, St. Petersburg, Russia
 
  In traditional approach, the Vlasov equation is considered as integro-differential equation. That formulation includes partial derivatives on phase coordinates. According to the covariant approach, physical relations should be presented by tensor equations. The main feature of the covariance is that any tensor equation can be written without using of coordinates. In covariant formulation of the Vlasov equation, we use such tensor objects as Lie derivatives. Classical and relativistic cases are described similarly. A difference between these two cases appears only in form of particle motion equations. Another feature of presented approach is consideration of degenerate distributions in the phase space. By degenerate distribution we mean a distribution having support of dimension smaller than dimension of the phase space. The simplest case of degenerate distribution is the distribution described by the Dirac measure. Another example is the Kapchinsky-Vladimirsky distribution, for which particles are distributed on the 3-dimensional surface in the 4-dimensional phase space.  
 
WEPC115 A Global Optimization Approach Based on Symbolic Presentation of a Beam Propagator 2280
 
  • S.N. Andrianov, A.N. Ivanov, M. Kosovtsov, E.A. Podzyvalov
    St. Petersburg State University, St. Petersburg, Russia
 
  It is known that modern systems of beam lines consist of huge control elements even in the case of small machines. The problem of the beam line design leads us to formulate this problem as a global optimization ones. This approach allows us defining a family of appropriate solutions. On the next steps a researcher should narrow this optimal solutions set using additional methods and concepts. The symbolic presentation of necessary information plays leading role on all steps of the suggested approach. The corresponding implementation presented in the paper allows us to find the optimal sets in parameters spaces in a proper way. The corresponding applied software was used for solution of some practical probems. The described ideology implies to use distributed and parallel technologies for necessary computing and will be integrated in the Virtual Accelerator concept.  
 
WEPC116 A Matrix Presentation for a Beam Propagator including Particles Spin 2283
 
  • M. Kosovtsov, S.N. Andrianov, A.N. Ivanov
    St. Petersburg State University, St. Petersburg, Russia
 
  Particles beam dynamics in magnetic and electrical fields with spin is discussed. This approach provides a constructive method of matrix presentation derivation for a beam propagator in magnetic and electrical fields. The beam propagator is evaluated in according to the well-known Lie algebraic tools. But in contrast to traditional approaches matrix presentation for Lie propagators bases on two-indexes matrices. This approach permit to apply all of matrix algebra opportunities and advantages in contrast with the tenzor presentation based on multi-indexes description. The necessary computation can be realized in symbolic (using computer algebra codes as Mathematica, Maple, Maxima and so on). The corresponding symbolic objects itself can be stored in special databases and used then in numerical computing. Parallel and distributed conception is well acceptable with the suggested matrix formalism. Some symbolic and numerical results are discussed for problems of long term evolution of particles with spin.  
 
WEPC117 Symmetry Based Design for Beam Lines* 2286
 
  • S.N. Andrianov, A.N. Ivanov, M. Kosovtsov
    St. Petersburg State University, St. Petersburg, Russia
 
  Usually, the beam line design problems are solved using numerical optimization methods (for example, in the frame of so called global optimization paradigm). But this approach demonstrates enough effectiveness only after sufficient reduction of a control parameters set. In this paper we present the symmetry design concept based on symbolic computations for the corresponding beam line propagator. The combination of symbolic algebra codes (such as Maple, Mathematica, Maxima and so on) with the matrix formalism for Lie algebraic tools enables us to carry out the entire theoretical and computing processes for design of the beam line under study. For this purpose some of necessary physical requirements are formulated in the terms of the corresponding symmetry conditions. The suggested approach can be realized in both exact and approximate forms of the symmetry terms. The found conditions can sufficiently reduce the number of control parameters for the next optimization step.  
 
WEPC119 PYMAD – Integration of MADX in PYTHON 2289
 
  • K. Fuchsberger, Y.I. Levinsen
    CERN, Geneva, Switzerland
 
  The de-facto standard software for modeling accelerator lattices at CERN is MADX (Methodical Accelerator Design), which is implemented and still maintained in the programming languages C and FORTRAN. For detailed processing, analysis and plotting of MADX results, other programming languages are often used. One very popular scripting language is PYTHON, which is widely used in the physics community and provides powerful numerical libraries and plotting routines. Therefore, access to MADX models from PYTHON is a common demand. Currently, several possible concepts for the realization of such a project are evaluated, including direct access to MADX via CYTHON (C extension of PYTHON) or the re-usage of the existing JMAD Java libraries, benefiting from the already available model-definitions. A first prototype is already in use and the release as an open source project is in preparation. This paper presents the concepts and the current status of the project, as well as some usage examples.  
 
WEPC120 Status of JMAD, the JAVA-API for MADX 2292
 
  • K. Fuchsberger, X. Buffat, Y.I. Levinsen, G.J. Müller
    CERN, Geneva, Switzerland
 
  MADX (Methodical Accelerator Design) is the de-facto standard software for modeling accelerator lattices at CERN. This feature-rich software package is implemented and still maintained in the programming languages C and FORTRAN. Nevertheless the controls environment of modern accelerators at CERN, e.g., of the LHC, is dominated by JAVA applications. A lot of these applications, for example, for lattice measurement and fitting, require a close interaction with the numerical models, which are all defined by the use of the proprietary MADX scripting language. To close this gap an API to MADX for the JAVA programming language (JMAD) was developed. JMAD was first presented to the public about one year ago. In the meantime, a number of improvements were done, and additional MADX features (e.g., tracking) were made available for JAVA applications. Additionally, the graphical user interface was improved, and the first release as open source software is in reach. This paper describes the current status and some new features of the project, as well as some usage examples.  
 
WEPC121 XML Constructs for Developing Dynamics Applications or Towards a Universal Representation of Particle Accelerators in XML 2295
 
  • J.T.M. Chrin, R.A. Krempaska, H. Lutz, G. Prekas
    PSI, Villigen, Switzerland
  • T.A. Pelaia
    ORNL, Oak Ridge, Tennessee, USA
 
  A recognized practice within the development of high-level beam dynamics applications is to separate data parameters destined for the configuration of the application from the programming language domain. The contemporary approach is to generate input files that provide the configuration parameters in a structured data format specified by the Extensible Markup Language (XML), enhancing flexibility and simplifying code maintenance. Furthermore, a careful choice of syntactic constructs, i.e. structured elements, attributes, etc., that map well to the various accelerator components, provides a basis for portability of applications. This has been exemplified by the XAL software package which initiated an XML description of the Standard Machine Format (SMF) accelerator object model. We have since adopted XML-SMF to provide an XML representation of both the Swiss Light Source (SLS) and the SwissFEL Injector Test Facility. We demonstrate how such XML constructs allow us to deploy the same orbit display application at both facilities. Our experience leads us to advocate a Universal Machine Format (UMF) that encompasses an all-inclusive XML schema for the management of accelerator information.  
poster icon Poster WEPC121 [0.313 MB]  
 
WEPC123 Numerical Algorithm based on the PDE Method for the Solution of the Fokker-Planck Equation 2298
 
  • M. Dolinska
    NASU/INR, Kiev, Ukraine
  • C. Dimopoulou, A. Dolinskii, F. Nolden, M. Steck
    GSI, Darmstadt, Germany
 
  Funding: Work supported by HIC for FAIR
This paper discus a fast and accurate algorithm for numerical solution of Fokker-Planck equation based on the solution of the parabolic Partial Differential Equations (PDE), where the Crank–Nicholson scheme is used. The stability, convergence and round-off errors of the algorithm are studied. The numerical results on Fokker–Planck equation solution with PDE method are compared with other numerical methods. Using the PDE solver, we will be able to predict the stochastic cooling process of notch filter in storage rings.
 
 
WEPC125 Higher Order Modes in Coupled Cavities of the FLASH Module ACC39 2301
 
  • R.M. Jones, I.R.R. Shinton
    UMAN, Manchester, United Kingdom
  • Z. Li
    SLAC, Menlo Park, California, USA
 
  We analyse the higher order modes (HOMs) in the 3.9GHz bunch shaping cavities installed in the FLASH facility at DESY. A suite of finite element computer codes (including HFSS and ACE3P) and globalised scattering matrix calculations are used to investigate the modes in these cavities. This study is primarily focused on the dipole component of the multiband expansion of the wakefield, with the emphasis being on the development of a HOM-based BPM system for ACC39. Coupled inter-cavity modes are simulated together with a limited band of trapped modes.  
 
WEPC128 Application of Dynamical Maps to the FFAG EMMA Commissioning* 2304
 
  • Y. Giboudot, R. Nilavalan
    Brunel University, Middlesex, United Kingdom
  • A. Wolski
    The University of Liverpool, Liverpool, United Kingdom
 
  Funding: Work supported by the Engineering and Physical Sciences Research Council, UK.
The lattice of the Non Scaling FFAG EMMA has four degrees of freedom (strengths and transverse positions of each of the two quadrupoles in each periodic cell). Dynamical maps computed from an analytical representation of the magnetic field may be used to predict the beam dynamics in any configuration of the lattice. An interpolation technique using a mixed variable generating function representation for the map provides an efficient way to generate the map for any required lattice configuration, while ensuring symplecticity of the map. The interpolation technique is used in an optimisation routine, to identify the lattice configuration most closely machine specified dynamical properties, including the variation of time of flight with beam energy (a key characteristic for acceleration in EMMA).
yoel.giboudot@stfc.ac.uk
 
 
WEPC132 Simulations of Surface Effects and Electron Emission from Diamond-Amplifier Cathodes 2307
 
  • D.A. Dimitrov, R. Busby, J.R. Cary, D.N. Smithe
    Tech-X, Boulder, Colorado, USA
  • I. Ben-Zvi
    Stony Brook University, Stony Brook, USA
  • X. Chang, T. Rao, J. Smedley, Q. Wu
    BNL, Upton, Long Island, New York, USA
  • E. Wang
    PKU/IHIP, Beijing, People's Republic of China
 
  Funding: The authors wish to acknowledge the support of the U.S. Department of Energy (DOE) under grants DE-SC0004431 (Tech-X Corp.), DE-AC02-98CH10886 (BNL), and DE-SC0005713 (Stony Brook University).
Emission of electrons in diamond experiments based on the promising diamond-amplifier concept* was recently demonstrated**. Transmission mode experiments have shown the potential to realize over two orders of magnitude charge amplification. However, the recent emission experiments indicate that surface effects should be understood in detail to build cathodes with optimal properties. We have made progress in understanding secondary electron generation and charge transport in diamond with models we implemented in the VORPAL particle-in-cell computational framework. We will introduce models that we have been implementing for surface effects (band bending and electron affinity), charge trapping, and electron emission from diamond. Then, we will present results from 3D VORPAL diamond-vacuum simulations with the integrated capabilities on generating electrons and holes, initiated by energetic primary electrons, charge transport, and then emission of electrons from diamond into vacuum. Finally, we will discuss simulation results on the dependence of the electron emission on diamond surface properties.
* I. Ben-Zvi et al., Secondary emission enhanced photoinjector, C-AD Accel. Phys. Rep. C-A/AP/149, BNL (2004).
** X. Chang et al., Phys. Rev. Lett. 105, 164801 (2010).
 
 
WEPC134 Unified Accelerator Modeling Using the Bmad Software Library 2310
 
  • D. Sagan, I.V. Bazarov, J.Y. Chee, J.A. Crittenden, G. Dugan, K. Finkelstein, G.H. Hoffstaetter, C.E. Mayes, S. Milashuk, D. L. Rubin, J.P. Shanks
    CLASSE, Ithaca, New York, USA
  • R. Cope
    CSU, Fort Collins, Colorado, USA
 
  Funding: Work supported by the National Science Foundation and by the US Department of Energy under contract numbers PHY-0734867 and DE-FC02-08ER41538.
The Bmad software library has proved to be a useful tool for accelerator simulations owing to its modular, object-oriented design. It is now used in a number of design, simulation and control programs at the Cornell Laboratory for Accelerator-based Sciences and Education. Work is ongoing to expand Bmad in a number of directions. One aim is tohave a complete framework in order to simulate Cornell's Energy Recovery Linac from Gun cathode (including space-charge) to photon generation to photon tracking through to the x-ray experimental end stations. Other work includes synchrotron radiation tracking including reflections from the vacuum chamber walls which is useful for electron cloud investigations, spin tracking, beam break-up instability, intra-beam scattering, etc. This paper will discuss the current state of the Bmad software along with the long-term goals.
 
 
WEPC135 Recent Developments in Modeling Time-resolved Shielded-pickup Measurements of Electron Cloud Buildup at CESRTA 2313
 
  • J.A. Crittenden, Y. Li, X. Liu, M.A. Palmer, J.P. Sikora
    CLASSE, Ithaca, New York, USA
  • R.P. Badman
    Syracuse University, Syracuse, USA
  • S. Calatroni, G. Rumolo
    CERN, Geneva, Switzerland
  • S. Kato
    KEK, Ibaraki, Japan
 
  Funding: Work supported by the U.S. National Science Foundation PHY-0734867, PHY-1002467 and the U.S. Department of Energy DE-FC02-08ER41538
The Cornell Electron Storage Ring Test Accelerator program includes investigations into the mitigation of electron cloud buildup using a variety of techniques in custom vacuum chambers. The CESR ring accommodates two such chambers equipped with BPM-style pickup detectors shielded against the direct beam-induced signal. The signals provide time-resolved information on cloud development. Results for diamond-like carbon, amorphous carbon, and TiN coatings have been compared to those for an uncoated aluminum chamber. Here we report on extensions to the ECLOUD modeling code which refine its description of a variety of new types of in situ vacuum chamber comparisons. Our results highlight the sensitivity afforded by these measurements to the modeled photoelectron production and secondary yield parameters. We draw conclusions comparing the photoelectron and secondary yield properties of the various vacuum chamber coatings, including conditioning effects as a function of synchrotron radiation dose. We find substantial conditioning effects in both the quantum efficiency for producing photoelectrons and in the secondary yield.
 
 
WEPC137 Undulator Radiation Simulation by QUINDI 2316
 
  • D. Schiller, E. Hemsing, J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
 
  QUINDI, a code developed to simulate coherent emission from bending systems, has been upgraded to include undulators as a beamline element. This approach allows us to better model the radiation produced by a relativistic electron bunch propagating through such a device.  
 
WEPC141 Application of the SYNRAD3D Photon-Tracking Model to Shielded Pickup Measurements of Electron Cloud Buildup at CesrTA 2319
 
  • L.E. Boon
    Purdue University, West Lafayette, Indiana, USA
  • J.A. Crittenden, T. Ishibashi
    CLASSE, Ithaca, New York, USA
  • K.C. Harkay
    ANL, Argonne, USA
 
  Funding: Work supported by U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
We present calculations of synchrotron radiation photon reflection in the vacuum chamber at the Cornell Electron Storage Ring Test Accelerator (CesrTA), applying them as input to the electron cloud buildup code ECLOUD to model time-resolved local measurements with shielded pickup detectors. The recently developed SYNRAD3D photon-tracking code employs a reflection model based on data from the Center for X-Ray Optics at LBNL. This study investigates the dependence of electron cloud buildup on the azimuthal position and kinetic energy distribution of photoelectron production on the vacuum chamber wall.
 
 
WEPS016 Update on Comparison of the Particle Production using MARS Simulation Code 2514
 
  • G. Prior, S.S. Gilardoni
    CERN, Geneva, Switzerland
  • X.P. Ding
    UCLA, Los Angeles, California, USA
  • H.G. Kirk, N. Souchlas
    BNL, Upton, Long Island, New York, USA
 
  Funding: EU FP7 EUROnu WP3
In the International Design Study for the Neutrino Factory (IDS-NF), a 5-15 GeV (kinetic energy) proton beam impinges a Hg jet target in order to produce pions that will decay into muons. The muons are then captured and transformed into a beam that can be passed to the downstream acceleration system. The target sits in a solenoid field tapering from 20 T down to below 2 T over several meters permitting a optimized capture of the pions that will produce useful muons for the machine. The target and pion capture system have been simulated in MARS simulation code and this work presents an updated comparison of the particles production using the MARS code versions m1507 and m1510.