Keyword: synchrotron
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MOAAI1 Project Overview and Computational Needs to Measure Electric Dipole Moments at Storage Rings storage-ring, simulation, dipole, proton 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]  
 
TUACC2 WAVE - A Computer Code for the Tracking of Electrons through Magnetic Fields and the Calculation of Spontaneous Synchrotron Radiation electron, radiation, undulator, synchrotron-radiation 86
 
  • M. Scheer
    HZB, Berlin, Germany
 
  WAVE has been developed since 1990 at BESSY - now Helmholtz-Zentrum Berlin (HZB) - to calculate spontaneous synchrotron radiation for arbitrary magnetic fields. A variety of field models for dipoles, wavelength shifters, and undulators is available. Field maps and tables can be read and written. Many routines to handle magnetic fields are implemented, including simulations of field error e.g. due to misalignment. Coherent radiation of electrons in a bunch and energy losses due to radiation are taken into account. Phase space distribution of electrons are taken into account by various algorithms. Generating functions and linear transfer matrices for particle tracking purposes can be calculated. Subroutines to calculate the effects of insertion devices on the storage ring are included. The program runs in batch mode, controlled by input files, but a simple GUI is also provided. The results are given as ASCII data or binary formats of the programs PAW, ROOT, and HDF5. Parallel runs of WAVE on a cluster are supported. WAVE has been checked and validated with the synchrotron radiation code of the German National Bureau of Standards (PTB) based on Schwinger's formula.  
slides icon Slides TUACC2 [3.685 MB]  
 
TUACC3 A Fast Integrated Green Function Method for Computing 1D CSR Wakefields Including Upstream Transients wakefield, lattice, radiation, dipole 89
 
  • C.E. Mitchell, J. Qiang, R.D. Ryne
    LBNL, Berkeley, California, USA
 
  Funding: This work is supported under DOE Contract No. DE-AC02-05CH11231.
An efficient numerical method for computing wakefields due to coherent synchrotron radiation (CSR) has been implemented using a one-dimensional integrated Green function approach. The contribution from CSR that is generated upstream and propagates across one or more lattice elements before interacting with the bunch is included. This method does not require computing the derivative of the longitudinal charge density, and accurately includes the short-range behavior of the CSR interaction. As an application of this method, we examine the importance of upstream transient wakefields within several bending elements of a proposed Next Generation Light Source.
 
slides icon Slides TUACC3 [2.060 MB]  
 
TUSCC3 Undulator Radiation Inside a Dielectric Waveguide radiation, vacuum, undulator, insertion 96
 
  • A. Kotanjyan, A.A. Saharian
    YSU, Yerevan, Armenia
 
  We investigate the radiation from a charge moving along a helix around a dielectric cylinder immersed in a homogeneous medium. We are mainly concerned with the radiation propagating inside the cylinder. The radiation intensity for the modes propagating inside the cylinder is evaluated by the work done by the radiation field on the charge and by evaluating the energy flux through the cross-section of the cylinder. The insertion of a dielectric waveguide provides an additional mechanism for tuning the characteristics of the undulator radiation by choosing the parameters of the waveguide. The radiated energy inside the cylinder is redistributed among the cylinder modes, the corresponding spectrum differs significantly from the homogeneous medium or free-space results. This change is of special interest in the low-frequency range where the distribution of the radiation energy among small number of modes leads to the enhancement of the spectral density for the radiation intensity. The radiation emitted on the waveguide modes propagates inside the cylinder and the waveguide serves as a natural collector for the radiation.  
slides icon Slides TUSCC3 [0.809 MB]  
 
TUSDI1 Modeling of Coherent Synchrotron Radiation Using a Direct Numerical Solution of Maxwell's Equations radiation, vacuum, electromagnetic-fields, dipole 107
 
  • A. Novokhatski
    SLAC, Menlo Park, California, USA
 
  Funding: Work supported by Department of Energy DE-AC02-76SF00515
We present and discuss the properties of coherent electromagnetic fields of a very short, ultra-relativistic bunch, which travels in a rectangular vacuum under the influence of a bending force of a magnet. The analysis is based on the results of a direct numerical solution of Maxwell’s equations together with Newton's equations. We use a new dispersion-free time-domain algorithm which employs a more efficient use of finite element mesh techniques and hence produces self-consistent and stable solutions for very short bunches. We investigate the fine structure of the CSR fields. We also discuss coherent edge radiation. We present a clear picture of the field using the electric field lines constructed from the numerical solutions. This approach should be useful in the study of existing and future concepts of particle accelerators and ultrafast coherent light sources, where high peak currents and very short bunches are envisioned.
 
slides icon Slides TUSDI1 [10.584 MB]  
 
WEAAC3 Dynamics of Ferrite Cavities and their Effect on Longitudinal Dipole Oscillations cavity, controls, simulation, resonance 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]  
 
WEP13 Model-Based Analysis of Digital Signal Processing Blocks in a Beam Phase Control System controls, dipole, ion, heavy-ion 164
 
  • C. Spies, M. Glesner
    TUD, Darmstadt, Germany
  • H. Klingbeil
    TEMF, TU Darmstadt, Darmstadt, Germany
 
  Funding: This work is supported by the German Federal Ministry of Education and Research under grant number 06DA9028I.
A beam phase control system comprises digital phase detectors and band pass filters to detect coherent longitudinal dipole and higher order bunch oscillations. These digital signal processing functions can be implemented in several ways, e. g. in software or on a programmable logic device. In this paper, we consider different possible implementations and compare them in terms of their real-time performance and their system resource consumption. For the phase detectors, a software implementation is compared against different (e. g. look-up table and CORDIC-based) hardware implementations. For the band pass filters, we consider software, hardware and mixed implementations.
 
 
THP02 Beam Dynamics Simulations Using GPUs simulation, controls, ion, linac 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.  
 
THACC2 Eigenmode Computation for Ferrite-Loaded Cavity Resonators cavity, resonance, heavy-ion, ion 250
 
  • K. Klopfer, W. Ackermann, T. Weiland
    TEMF, TU Darmstadt, Darmstadt, Germany
 
  Funding: Work supported by GSI
For acceleration of charged particles at the heavy-ion synchrotron at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt two ferrite-loaded cavity resonators are installed within the ring. Their eigenfrequency can be tuned by properly choosing a bias current and thereby modifying the differential permeability of the ferrite material. The goal of the presented work is to numerically determine the lowest eigensolutions of accelerating ferrite-loaded cavities based on the Finite Integration Technique. The newly developed solver includes two subcomponents: Firstly, a magnetostatic solver supporting nonlinear material for the computation of the magnetic field which is excited by the specified bias current. This enables to linearize the constitutive equation for the ferrite material at the current working point, at which also the differential permeability tensor is evaluated. Secondly, a Jacobi-Davidson type eigensolver for the subsequent solution of the nonlinear eigenvalue problem. Particular emphasis is put on the implementation to enable efficient distributed parallel computing. First numerical results for biased ferrite-filled cavity resonators are presented.
 
slides icon Slides THACC2 [1.105 MB]  
 
THSDI2 Simulation of Multibunch Instabilities with the HEADTAIL Code simulation, impedance, octupole, wakefield 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 simulation, 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]