Keyword: synchrotron
Paper Title Other Keywords Page
SAPAF02 Optimization of Heavy-Ion Synchrotrons Using Nature-Inspired Algorithms and Machine Learning injection, emittance, simulation, space-charge 15
  • S. Appel, W. Geithner, S. Reimann, M. Sapinski, R. Singh, D.M. Vilsmeier
    GSI, Darmstadt, Germany
  The application of machine learning and nature-inspired optimization methods, like for example genetic algorithms (GA) and particle swarm optimization (PSO) can be found in various scientific/technical areas. In recent years, those approaches are finding application in accelerator physics to a greater extent. In this report, nature-inspired optimization as well as the machine learning will be shortly introduced and their application to the accelerator facility at GSI/FAIR will be presented. For the heavy-ion synchrotron SIS18 at GSI, the multi-objective GA/PSO optimization resulted in a significant improvement of multi-turn injection performance and subsequent transmission for intense beams. An automated injection optimization with genetic algorithms at the CRYRING@ESR ion storage ring has been performed. The usage of machine learning for a beam diagnostic application, where reconstruction of space-charge distorted beam profiles from ionization profile monitors is performed, will also be shown. First results and the experience gained will be presented.  
slides icon Slides SAPAF02 [2.642 MB]  
DOI • reference for this paper ※  
About • paper received ※ 16 October 2018       paper accepted ※ 27 January 2019       issue date ※ 26 January 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
MOPLG03 Spin Dynamics in Modern Electron Storage Rings: Computational and Theoretical Aspects polarization, storage-ring, electron, radiation 127
  • K.A. Heinemann, O. Beznosov, J.A. Ellison
    UNM, Albuquerque, New Mexico, USA
  • D. Appelö
    University of Colorado at Boulder, Boulder, USA
  • D.P. Barber
    DESY, Hamburg, Germany
  Funding: U.S. Department of Energy, Office of Science, Office of High Energy Physics, Award Number DE-SC0018008
In this talk we present some numerical and analytical results from our work on the spin polarization in high energy electron storage rings. Our work is based on the initial value problem of what we call the full Bloch equations (FBEs). The solution of the FBEs is the polarization density which is proportional to the spin angular momentum density per particle in phase space and which determines the polarization vector of the bunch. The FBEs take into account spin diffusion effects and spin-flip effects due to synchrotron radiation including the Sokolov-Ternov effect and its Baier-Katkov generalization. The FBEs were introduced by Derbenev and Kondratenko in 1975 as a generalization of the Baier-Katkov-Strakhovenko equations from a single orbit to the whole phase space. The FBEs are a system of three uncoupled Fokker-Planck equations plus two coupling terms, i.e., the T-BMT term and the Baier-Katkov term. Neglecting the spin flip terms in the FBEs one gets what we call the reduced Bloch equations (RBEs). The RBEs are sufficient for computing the depolarization time. The conventional approach of estimating and optimizing the polarization is not based on the FBEs but on the so-called Derbenev-Kondratenko formulas. However, we believe that the FBEs offer a more complete starting point for very high energy rings like the FCC-ee and CEPC. The issues for very high energy are: (i) Can one get polarization, (ii) are the Derbenev-Kondratenko formulas satisfactory at very high energy? If not, what are the theoretical limits of the polarization? Item (ii) will be addressed both numerically and analytically. Our numerical approach has three parts. Firstly we approximate the FBEs analytically using the method of averaging, resulting in FBEs which allow us to use large time steps (without the averaging the time dependent coefficients of the FBEs would necessitate small time steps). The minimum length of the time interval of interest is of the order of the orbital damping time. Seco
slides icon Slides MOPLG03 [0.465 MB]  
DOI • reference for this paper ※  
About • paper received ※ 20 October 2018       paper accepted ※ 24 October 2018       issue date ※ 26 January 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
TUPAF01 Upgrade of MAD-X for HL-LHC Project and FCC Studies radiation, coupling, synchrotron-radiation, lattice 165
  • L. Deniau, H. Burkhardt, R. De Maria, M. Giovannozzi, J.M. Jowett, A. Latina, T. Persson, F. Schmidt, I.S. Shreyber, P.K. Skowroński
    CERN, Geneva, Switzerland
  • T.G. Gläßle
    HIT, Heidelberg, Germany
  The design efforts for the High Luminosity upgrade of the Large Hadron Collider (HL-LHC) and for the FCC-ee project required significant extensions of the MAD-X code widely used for designing and simulating particle accelerators. The modelling of synchrotron radiation effects has recently been reviewed, improved and tested on the lattices of ESRF, LEP and CLIC Final Focus System. The results were cross checked with the codes AT, PLACET, Geant4, and MAD8. The implementation of space charge has been drastically restructured in a modular design. The linear coupling calculation has been completely reviewed and improved, from the theory to the implementation in MAD-X code to ensure its correctness in the presence of strong coupling as in the HL-LHC studies. The slicing module has been generalised to allow for thick slices of bending magnets, quadrupoles and solenoids. The SBEND element has been extended to support difference between bending angle and integrated dipole strength. Patches have been added to the list of supported elements. MAD-X PTC has also been extended to track resonance driving terms along layouts, and to support AC dipoles to simulate beams during optics measurements.  
slides icon Slides TUPAF01 [5.986 MB]  
DOI • reference for this paper ※  
About • paper received ※ 17 October 2018       paper accepted ※ 24 October 2018       issue date ※ 26 January 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
TUPAF06 Simulations of Longitudinal Beam Stabilisation in the CERN SPS With BLonD simulation, impedance, emittance, flattop 179
  • J. Repond, K. Iliakis, M. Schwarz, E.N. Shaposhnikova
    CERN, Meyrin, Switzerland
  The Super Proton Synchrotron (SPS) at CERN, the Large Hadron Collider (LHC) injector, will be pushed to its limits for the production of the High Luminosity LHC proton beam while beam quality and stability in the longitudinal plane are influenced by many effects. Particle simulation codes are an essential tool to study the beam instabilities. BLonD, developed at CERN, is a 2D particle-tracking simulation code, modelling the longitudinal phase space motion of single and multi-bunch beams in multi-harmonic RF systems. Computation of collective effects due to the machine impedance and space charge is done on a multi-turn basis. Various beam and cavity control loops of the RF system are implemented (phase, frequency and synchro-loops, and one-turn delay feedback) as well as RF phase noise injection used for controlled emittance blow-up. The longitudinal beam stability simulations during long SPS acceleration cycle (~ 20 s) include a variety of effects (beam loading, particle losses, controlled blow-up, double RF system operation, low-level RF control, injected bunch distribution, etc.). Simulations for the large number of bunches in the nominal LHC batch (288) use the longitudinal SPS impedance model containing broad and narrow-band resonances between 50 MHz and 4 GHz. This paper presents a study of beam stabilisation in the double harmonic RF system of the SPS system with results substantiated, where possible, by beam measurements.  
slides icon Slides TUPAF06 [1.518 MB]  
DOI • reference for this paper ※  
About • paper received ※ 18 October 2018       paper accepted ※ 24 October 2018       issue date ※ 26 January 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
TUPAF12 Longitudinal Beam Dynamics With a Higher-Harmonic Cavity for Bunch Lengthening cavity, operation, storage-ring, simulation 202
  • G. Bassi, J. Tagger
    BNL, Upton, Long Island, New York, USA
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy
We discuss the longitudinal beam dynamics in storage rings in the presence of a higher-harmonic cavity (HHC) system for bunch lengthening. We first review the general conditions for HHC operations, either in active or passive mode, assuming the stability of the system. For uniform filling patterns, a distinction is made between operations with a normal-conducting HHC, where optimal conditions for bunch lengthening can be satisfied, and operations with super-conducting HHC, where optimal conditions can be met only approximately. The option to operate the NSLS-II storage ring with a passive, super-conducting third harmonic cavity (3HC) system is discussed next. The stability and performance of the system in the presence of a gap in the uniform filling, which corresponds to the present mode of operation of the NSLS-II storage ring, is investigated with self-consistent Vlasov-Fokker-Planck simulations performed with the code SPACE*.
* G. Bassi, A. Blednykh and V. Smaluk, Phys Rev. Accel. Beams 19, 024401 (2016).
slides icon Slides TUPAF12 [17.562 MB]  
DOI • reference for this paper ※  
About • paper received ※ 20 October 2018       paper accepted ※ 28 January 2019       issue date ※ 26 January 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
TUPAG17 Beamline Map Computation for Paraxial Optics FEL, radiation, optics, electron 297
  • B. Nash, J.P. Edelen, N.B. Goldring, S.D. Webb
    RadiaSoft LLC, Boulder, Colorado, USA
  Funding: Department of Energy office of Basic energy sciences, DE-SC0018571
Modeling of radiation transport is an important topic tightly coupled to many charged particle dynamics simulations for synchrotron light sources and FEL facilities. The radiation is determined by the electron beam and magnetic field source, and then passes through beamlines with focusing elements, apertures and monochromators, in which one may typically apply the paraxial approximation of small angular deviations from the optical axis. The radiation is then used in a wide range of spectroscopic experiments, or else may be recirculated back to the electron beam source, in the case of an FEL oscillator. The Wigner function representation of electromagnetic wavefronts has been described in the literature and allows a phase space description of the radiation, similar to that used in charged particle dynamics. It can encompass both fully and partially coherent cases, as well as polarization. Here, we describe the calculation of a beamline map that can be applied to the radiation Wigner function, reducing the computation time. We discuss the use of ray tracing and wave optics codes for the map computation and benchmarking. We construct a four crystal 1:1 imaging beamline that could be used for recirculation in an XFEL oscillator, and benchmark the map based results with SRW wavefront simulations.
slides icon Slides TUPAG17 [2.289 MB]  
DOI • reference for this paper ※  
About • paper received ※ 19 October 2018       paper accepted ※ 18 December 2018       issue date ※ 26 January 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)