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Title: Modeling laser wakefield accelerators in a Lorentz boosted frame

Abstract

Modeling of laser-plasma wakefield accelerators in an optimal frame of reference is shown to produce orders of magnitude speed-up of calculations from first principles. Obtaining these speedups requires mitigation of a high-frequency instability that otherwise limits effectiveness in addition to solutions for handling data input and output in a relativistically boosted frame of reference. The observed high-frequency instability is mitigated using methods including an electromagnetic solver with tunable coefficients, its extension to accomodate Perfectly Matched Layers and Friedman's damping algorithms, as well as an efficient large bandwidth digital filter. It is shown that choosing the frame of the wake as the frame of reference allows for higher levels of filtering and damping than is possible in other frames for the same accuracy. Detailed testing also revealed serendipitously the existence of a singular time step at which the instability level is minimized, independently of numerical dispersion, thus indicating that the observed instability may not be due primarily to Numerical Cerenkov as has been conjectured. The techniques developed for Cerenkov mitigation prove nonetheless to be very efficient at controlling the instability. Using these techniques, agreement at the percentage level is demonstrated between simulations using different frames of reference, with speedups reaching twomore » orders of magnitude for a 0.1 GeV class stages. The method then allows direct and efficient full-scale modeling of deeply depleted laser-plasma stages of 10 GeV-1 TeV for the first time, verifying the scaling of plasma accelerators to very high energies. Over 4, 5 and 6 orders of magnitude speedup is achieved for the modeling of 10 GeV, 100 GeV and 1 TeV class stages, respectively.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
Accelerator& Fusion Research Division
OSTI Identifier:
985930
Report Number(s):
LBNL-3746E
Journal ID: ISSN 0021-9991; JCTPAH; TRN: US1006273
DOE Contract Number:  
DE-AC02-05CH11231
Resource Type:
Journal Article
Journal Name:
Journal of Computational Physics
Additional Journal Information:
Journal Name: Journal of Computational Physics; Journal ID: ISSN 0021-9991
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ACCURACY; ALGORITHMS; DAMPING; DIGITAL FILTERS; INSTABILITY; LASERS; MITIGATION; PLASMA GUNS; SIMULATION; TESTING; WAKEFIELD ACCELERATORS

Citation Formats

Vay, J -L, Geddes, C G.R., Cormier-Michel, E, and Grotec, D P. Modeling laser wakefield accelerators in a Lorentz boosted frame. United States: N. p., 2010. Web. doi:10.1063/1.3520322.
Vay, J -L, Geddes, C G.R., Cormier-Michel, E, & Grotec, D P. Modeling laser wakefield accelerators in a Lorentz boosted frame. United States. doi:10.1063/1.3520322.
Vay, J -L, Geddes, C G.R., Cormier-Michel, E, and Grotec, D P. Tue . "Modeling laser wakefield accelerators in a Lorentz boosted frame". United States. doi:10.1063/1.3520322. https://www.osti.gov/servlets/purl/985930.
@article{osti_985930,
title = {Modeling laser wakefield accelerators in a Lorentz boosted frame},
author = {Vay, J -L and Geddes, C G.R. and Cormier-Michel, E and Grotec, D P},
abstractNote = {Modeling of laser-plasma wakefield accelerators in an optimal frame of reference is shown to produce orders of magnitude speed-up of calculations from first principles. Obtaining these speedups requires mitigation of a high-frequency instability that otherwise limits effectiveness in addition to solutions for handling data input and output in a relativistically boosted frame of reference. The observed high-frequency instability is mitigated using methods including an electromagnetic solver with tunable coefficients, its extension to accomodate Perfectly Matched Layers and Friedman's damping algorithms, as well as an efficient large bandwidth digital filter. It is shown that choosing the frame of the wake as the frame of reference allows for higher levels of filtering and damping than is possible in other frames for the same accuracy. Detailed testing also revealed serendipitously the existence of a singular time step at which the instability level is minimized, independently of numerical dispersion, thus indicating that the observed instability may not be due primarily to Numerical Cerenkov as has been conjectured. The techniques developed for Cerenkov mitigation prove nonetheless to be very efficient at controlling the instability. Using these techniques, agreement at the percentage level is demonstrated between simulations using different frames of reference, with speedups reaching two orders of magnitude for a 0.1 GeV class stages. The method then allows direct and efficient full-scale modeling of deeply depleted laser-plasma stages of 10 GeV-1 TeV for the first time, verifying the scaling of plasma accelerators to very high energies. Over 4, 5 and 6 orders of magnitude speedup is achieved for the modeling of 10 GeV, 100 GeV and 1 TeV class stages, respectively.},
doi = {10.1063/1.3520322},
journal = {Journal of Computational Physics},
issn = {0021-9991},
number = ,
volume = ,
place = {United States},
year = {2010},
month = {6}
}