Author: Adelmann, A.
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SUPAF11
 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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SUPAF12
 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. 		 
slides icon Slides MOPLG01 [3.947 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-MOPLG01  
About • paper received ※ 20 October 2018       paper accepted ※ 24 October 2018       issue date ※ 26 January 2019  
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TUPAF07
 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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TUPAG05
 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 ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAG14  
About • paper received ※ 19 October 2018       paper accepted ※ 10 December 2018       issue date ※ 26 January 2019  
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