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Title: Numerical methods for instability mitigation in the modeling of laser wakefield accelerators in a Lorentz-boosted frame

Abstract

Modeling of laser-plasma wakefield accelerators in an optimal frame of reference has been shown to produce orders of magnitude speed-up of calculations from first principles. Obtaining these speedups required mitigation of a high-frequency instability that otherwise limits effectiveness. In this paper, methods are presented which mitigated the observed instability, including an electromagnetic solver with tunable coefficients, its extension to accommodate Perfectly Matched Layers and Friedman's damping algorithms, as well as an efficient large bandwidth digital filter. It is observed that choosing the frame of the wake as the frame of reference allows for higher levels of filtering or damping than is possible in other frames for the same accuracy. Detailed testing also revealed the existence of a singular time step at which the instability level is minimized, independently of numerical dispersion. A combination of the techniques presented in this paper prove to be very efficient at controlling the instability, allowing for efficient direct modeling of 10 GeV class laser plasma accelerator stages. The methods developed in this paper may have broader application, to other Lorentz-boosted simulations and Particle-In-Cell simulations in general.

Authors:
 [1];  [2];  [3]
  1. Lawrence Berkeley National Lab., 1 Cyclotron Road, Berkeley, CA 94720 (United States)
  2. Tech-X Corporation, 5621 Arapahoe Ave., Suite A, Boulder, CO, 80303 (United States)
  3. Lawrence Livermore National Lab., L-637, Livermore, CA 94550 (United States)
Publication Date:
OSTI Identifier:
21592597
Resource Type:
Journal Article
Journal Name:
Journal of Computational Physics
Additional Journal Information:
Journal Volume: 230; Journal Issue: 15; Other Information: DOI: 10.1016/j.jcp.2011.04.003; PII: S0021-9991(11)00227-0; Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-9991
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 97 MATHEMATICAL METHODS AND COMPUTING; ACCELERATION; ALGORITHMS; DIGITAL FILTERS; GEV RANGE 01-10; INSTABILITY; LASERS; PLASMA; PLASMA GUNS; PLASMA SIMULATION; RELATIVITY THEORY; WAKEFIELD ACCELERATORS; ACCELERATORS; ENERGY RANGE; GEV RANGE; LINEAR ACCELERATORS; MATHEMATICAL LOGIC; SIMULATION

Citation Formats

Vay, J.-L., E-mail: jlvay@lbl.gov, Geddes, C G.R., Cormier-Michel, E, and Grote, D P. Numerical methods for instability mitigation in the modeling of laser wakefield accelerators in a Lorentz-boosted frame. United States: N. p., 2011. Web. doi:10.1016/j.jcp.2011.04.003.
Vay, J.-L., E-mail: jlvay@lbl.gov, Geddes, C G.R., Cormier-Michel, E, & Grote, D P. Numerical methods for instability mitigation in the modeling of laser wakefield accelerators in a Lorentz-boosted frame. United States. doi:10.1016/j.jcp.2011.04.003.
Vay, J.-L., E-mail: jlvay@lbl.gov, Geddes, C G.R., Cormier-Michel, E, and Grote, D P. Fri . "Numerical methods for instability mitigation in the modeling of laser wakefield accelerators in a Lorentz-boosted frame". United States. doi:10.1016/j.jcp.2011.04.003.
@article{osti_21592597,
title = {Numerical methods for instability mitigation in the modeling of laser wakefield accelerators in a Lorentz-boosted frame},
author = {Vay, J.-L., E-mail: jlvay@lbl.gov and Geddes, C G.R. and Cormier-Michel, E and Grote, D P},
abstractNote = {Modeling of laser-plasma wakefield accelerators in an optimal frame of reference has been shown to produce orders of magnitude speed-up of calculations from first principles. Obtaining these speedups required mitigation of a high-frequency instability that otherwise limits effectiveness. In this paper, methods are presented which mitigated the observed instability, including an electromagnetic solver with tunable coefficients, its extension to accommodate Perfectly Matched Layers and Friedman's damping algorithms, as well as an efficient large bandwidth digital filter. It is observed that choosing the frame of the wake as the frame of reference allows for higher levels of filtering or damping than is possible in other frames for the same accuracy. Detailed testing also revealed the existence of a singular time step at which the instability level is minimized, independently of numerical dispersion. A combination of the techniques presented in this paper prove to be very efficient at controlling the instability, allowing for efficient direct modeling of 10 GeV class laser plasma accelerator stages. The methods developed in this paper may have broader application, to other Lorentz-boosted simulations and Particle-In-Cell simulations in general.},
doi = {10.1016/j.jcp.2011.04.003},
journal = {Journal of Computational Physics},
issn = {0021-9991},
number = 15,
volume = 230,
place = {United States},
year = {2011},
month = {7}
}