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

Journal Article · Fri Jul 01 00:00:00 EDT 2011 · Journal of Computational Physics

DOI:https://doi.org/10.1016/j.jcp.2011.04.003· OSTI ID:21592597

Geddes, C G.R. ^[1]; Cormier-Michel, E ^[2]; Grote, D P ^[3]

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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)

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.

• OSTI ID: 21592597
• Journal Information: Journal of Computational Physics, Vol. 230, 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); ISSN 0021-9991
• Country of Publication: United States
• Language: English

Related Subjects

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