Author: Adelmann, A.
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Computer Architecture Independent Adaptive Geometric Multigrid Solver for AMR-PIC  
  • M. Frey, A. Adelmann
    PSI, Villigen PSI, Switzerland
  Funding: SNSF project 200021159936
The accurate and efficient simulation of neighboring bunch effects in high intensity cyclotrons requires to solve large-scale N-body problems of O(109…10zEhNZeHn) particles coupled with Maxwell’s equations. In order to capture the effects of halo creation and evolution of such simulations with standard particle-in-cell models an extremely fine mesh with O(108…109) grid points is necessary to meet the condition of high resolution. This requirement represents a waste of memory in regions of void, therefore, the usage of block-structured adaptive mesh refinement algorithms is more suitable. The N-body problem is then solved on a hierarchy of levels and grids using geometric multigrid algorithms. We show benchmarks of a new implementation of an adaptive geometric multigrid algorithm using 2nd generation Trilinos packages that ran on Piz Daint with O(104…105) cores.
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Surrogate Models for Beam Dynamics in Charged Particle Accelerators  
  • A.L. Edelen
    SLAC, Menlo Park, California, USA
  • D. Acharya, A. Adelmann, M. Frey
    PSI, Villigen PSI, Switzerland
  • N.R. Neveu
    ANL, Argonne, Illinois, USA
  High-fidelity, PIC-based beam dynamics simulations are time and resource intensive. Consider a high dimensional search space, that is far too large to probe with such a high resolution simulation model. We demonstrate that a coarse sampling of the search space can produce surrogate models, which are accurate and fast to evaluate. In constructing the surrogate models, we use artificial neural networks [1] and multivariate polynomial chaos expansion [2]. The performance of both methods are demonstrated in a comparison with high-fidelity simulations, using OPAL, of the Argonne Wakefield Accelerator [3]. We claim that such surrogate models are good candidates for accurate on-line modeling of large, complex accelerator systems. We also address how to estimate the accuracy of the surrogate model and how to refine the surrogate model under changing machine conditions. [1] A. L. Edelen et al., arXiv:1610.06151[physics.acc- ph] [2] A. Adelmann, arXiv:1509.08130v6[physics.acc- ph] [3] N. Neveu et al., 2017 J. Phys.: Conf. Ser. 874 012062  
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MOPLG01 Challenges in Simulating Beam Dynamics of Dielectric Laser Acceleration 120
  • U. Niedermayer, O. Boine-Frankenheim, T. Egenolf, E. Skär
    TEMF, TU Darmstadt, Darmstadt, Germany
  • A. Adelmann, S. Bettoni, M. Calvi, M.M. Dehler, E. Ferrari, F. Frei, D. Hauenstein, B. Hermann, N. Hiller, R. Ischebeck, C. Lombosi, E. Prat, S. Reiche, L. Rivkin
    PSI, Villigen PSI, Switzerland
  • R.W. Aßmann, U. Dorda, M. Fakhari, I. Hartl, W. Kuropka, F. Lemery, B. Marchetti, F. Mayet, H. Xuan, J. Zhu
    DESY, Hamburg, Germany
  • D.S. Black, P. N. Broaddus, R.L. Byer, A.C. Ceballos, H. Deng, S. Fan, J.S. Harris, T. Hirano, Z. Huang, T.W. Hughes, Y. Jiang, T. Langenstein, K.J. Leedle, Y. Miao, A. Pigott, N. Sapra, O. Solgaard, L. Su, S. Tan, J. Vuckovic, K. Yang, Z. Zhao
    Stanford University, Stanford, California, USA
  • H. Cankaya, A. Fallahi, F.X. Kärtner
    CFEL, Hamburg, Germany
  • D.B. Cesar, P. Musumeci, B. Naranjo, J.B. Rosenzweig, X. Shen
    UCLA, Los Angeles, California, USA
  • B.M. Cowan
    Tech-X, Boulder, Colorado, USA
  • R.J. England
    SLAC, Menlo Park, California, USA
  • E. Ferrari, L. Rivkin
    EPFL, Lausanne, Switzerland
  • T. Feurer
    Universität Bern, Institute of Applied Physics, Bern, Switzerland
  • P. Hommelhoff, A. Li, N. Schönenberger, R. Shiloh, A.D. Tafel, P. Yousefi
    University of Erlangen-Nuremberg, Erlangen, Germany
  • Y.-C. Huang
    NTHU, Hsinchu, Taiwan
  • J. Illmer, A.K. Mittelbach
    Friedrich-Alexander Universität Erlangen-Nuernberg, University Erlangen-Nuernberg LFTE, Erlangen, Germany
  • F.X. Kärtner
    Deutsches Elektronen Synchrotron (DESY) and Center for Free Electron Science (CFEL), Hamburg, Germany
  • W. Kuropka, F. Mayet
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • Y.J. Lee, M. Qi
    Purdue University, West Lafayette, Indiana, USA
  • E.I. Simakov
    LANL, Los Alamos, New Mexico, USA
  Funding: ACHIP is funded by the Gordon and Betty Moore Foundation (Grant No. GBMF4744). U.N. acknowledges German BMBF Grant No. FKZ:05K16RDB. B.C. acknowledges NERSC, Contract No. DE-AC02-05CH11231.
Dielectric Laser Acceleration (DLA) achieves the high- est gradients among structure-based electron accelerators. The use of dielectrics increases the breakdown field limit, and thus the achievable gradient, by a factor of at least 10 in comparison to metals. Experimental demonstrations of DLA in 2013 led to the Accelerator on a Chip International Program (ACHIP), funded by the Gordon and Betty Moore Foundation. In ACHIP, our main goal is to build an acceler- ator on a silicon chip, which can accelerate electrons from below 100keV to above 1MeV with a gradient of at least 100MeV/m. For stable acceleration on the chip, magnet- only focusing techniques are insufficient to compensate the strong acceleration defocusing. Thus spatial harmonic and Alternating Phase Focusing (APF) laser-based focusing tech- niques have been developed. We have also developed the simplified symplectic tracking code DLAtrack6D, which makes use of the periodicity and applies only one kick per DLA cell, which is calculated by the Fourier coefficient of the synchronous spatial harmonic. Due to coupling, the Fourier coefficients of neighboring cells are not entirely independent and a field flatness optimization (similarly as in multi-cell cavities) needs to be performed. The simu- lation of the entire accelerator on a chip by a Particle In Cell (PIC) code is possible, but impractical for optimization purposes. Finally, we have also outlined the treatment of wake field effects in attosecond bunches in the grating within DLAtrack6D, where the wake function is computed by an external solver.
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DOI • reference for this paper ※  
About • paper received ※ 20 October 2018       paper accepted ※ 24 October 2018       issue date ※ 26 January 2019  
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Recent Developments of the Open Source Code OPAL  
  • A. Adelmann
    PSI, Villigen PSI, Switzerland
  After a general introduction of OPAL, I will introduce a set of new features available with version 2.0 released in July 2018. All new features will be presented together with examples of ongoing research projects. In the OPAL-t flavour, elements can now be placed in 3D, without restriction. Overlapping fringe fields are handled, and off-momentum beams as occurring in tolerance studies can be tracked. Furthermore, survey plots of placed elements are a valuable diagnostic when dealing with complex designs. A new element, a flexibly configurable collimator, will be presented. In the OPAL-cyc flavour, a robust way of generating matched distributions with linear space charge is introduced. A new method for describing fixed field accelerators (FFAs) in a very general way will be shown. A new element TRIMCOIL can be used to correct for field-errors in cyclotrons and FFAs. The OPAL language (a derivative of the MAD language) was extended to allow the specification of multi objective optimisation problems, which are then solved with a built in NGSA-II genetic algorithm. A new feature SAMPLER allows you to setup and run random or sequential parameter studies and seamless utilisation of a vast number of computing cores. Finally, a set of Python tools (pyOPALTools) was created for post processing. The manual is now available on the OPAL-wiki as well as in pdf format.  
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Trimcoil Optimisation Using Multi-Objective Optimisation Techniques and HPC  
  • M. Frey, A. Adelmann, J. Snuverink
    PSI, Villigen PSI, Switzerland
  Funding: SNSF project 200021159936
Uncertainties in the bunch injection (i.e. energy, radius, radial momentum and angle) as well as magnet inaccuracies harm the isochronicity of the PSI 590 MeV Ring Cyclotron. An additional magnetic field provided by trim coils is an effective solution to restore this condition. Therefore, an accurate description of trim coils is essential to match the turn pattern of the machine in simulations. However, due to the high-dimensional search space consisting of 21 design variables and more than 180 objectives the turns cannot be matched in a straightforward manner and without sufficient HPC resources. In this talk we present a realistic trim coil model for the PSI 590 MeV Ring Cyclotron implemented in OPAL that was used together with its built-in multi-objective optimisation algorithm to find the 4 injection parameters and the magnetic field strengths of 17 trim coils. The optimisations were performed on Piz Daint (currently 3rd fastest supercomputer world-wide) with more than 1000 cores per job.
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TUPAG14 Constrained Multi-Objective Shape Optimization of Superconducting RF Cavities to Counteract Dangerous Higher Order Modes 293
  • M. Kranjcevic, P. Arbenz
    ETH, Zurich, Switzerland
  • A. Adelmann
    PSI, Villigen PSI, Switzerland
  • S. Gorgi Zadeh, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  High current storage rings, such as the Z operating mode of the FCC-ee, require superconducting radio frequency (RF) cavities that are optimized with respect to both the fundamental mode and the dangerous higher order modes. In order to optimize the shape of the RF cavity, a constrained multi-objective optimization problem is solved using a massively parallel implementation of an evolutionary algorithm. Additionally, a frequency-fixing scheme is employed to deal with the constraint on the frequency of the fundamental mode. Finally, the computed Pareto front approximation and an RF cavity shape with desired properties are shown.  
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DOI • reference for this paper ※  
About • paper received ※ 19 October 2018       paper accepted ※ 10 December 2018       issue date ※ 26 January 2019  
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