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Determination of the growth rate for the linearized Zakharov—Kuznetsov equation

Published online by Cambridge University Press:  13 March 2009

M. A. Allen
Affiliation:
Department of Physics, University of Warwick, Coventry CV4 7AL, U.K.
G. Rowlands
Affiliation:
Department of Physics, University of Warwick, Coventry CV4 7AL, U.K.

Abstract

Studies of the Zakharov—Kuznetsov equation governing solitons in a strongly magnetized ion-acoustic plasma indicate that a perturbed flat soliton is unstable and evolves into higher-dimensional solitons. The growth rate γ = γ(k) of a small sinusoidal perturbation of wavenumber k to a flat soliton has already been found numerically, and lengthy analytical work has given the value of We introduce a more direct analytical method in the form of an extension to the usual multiple-scale perturbation approach and use it to determine a consistent expansion of γ about k = 0 and the other zero at k2 = 5.By combining these results in the form of a two-point Padé approximant, we obtain an analytical expression for γ valid over the entire range of k for which the solution is unstable. We also present a very efficient numerical method for determining the growth rate curve to great accuracy. The Padé approximant gives excellent agreement with the numerical results.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1993

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