Perturbation theory for solitons of the Fokas--Lenells equation : Inverse scattering transform approach

Abstract

We present perturbation theory based on the inverse scattering transform method for solitons described by an equation with the inverse linear dispersion law $\omega \sim 1/k$, where $\omega$ is the frequency and $k$ is the wave number, and cubic nonlinearity. This equation, first suggested by Davydova and Lashkin for describing dynamics of nonlinear short-wavelength ion-cyclotron waves in plasmas and later known as the Fokas--Lenells equation, arises from the first negative flow of the Kaup--Newell hierarchy. Local and nonlocal integrals of motion, in particular the energy and momentum of nonlinear ion-cyclotron waves, are explicitly expressed in terms of the discrete (solitonic) and continuous (radiative) scattering data. Evolution equations for the scattering data in the presence of a perturbation are presented. Spectral distributions in the wave number domain of the energy emitted by the soliton in the presence of a perturbation are calculated analytically for two cases: (i) linear damping that corresponds to Landau damping of plasma waves, and (ii) multiplicative noise which corresponds to thermodynamic fluctuations of the external magnetic field (thermal noise) and/or the presence of a weak plasma turbulence.

References in corpus (2)

• On a novel integrable generalization of the nonlinear Schrödinger equation
• Stable three-dimensional modon soliton in plasmas

Cited by in corpus (1)

• $N$-soliton solutions of the Fokas-Lenells equation for the plasma ion-cyclotron waves: Inverse scattering transform approach