Kinetic Alfvén solitary and rogue waves in superthermal plasmas

Abstract

We investigate the small but finite amplitude solitary Kinetic Alfvén waves (KAWs) in low β plasmas with superthermal electrons modeled by a kappa-type distribution. A nonlinear Korteweg-de Vries (KdV) equation describing the evolution of KAWs is derived by using the standard reductive perturbation method. Examining the dependence of the nonlinear and dispersion coefficients of the KdV equation on the superthermal parameter κ, plasma β and obliqueness of propagation, we show that these parameters may change substantially the shape and size of solitary KAW pulses.Only sub-Alfvénic, compressive solitons are supported. We then extend the study to examine kinetic Alfvén rogue waves by deriving a nonlinear Schrödinger equation from the KdV equation. Rational solutions that form rogue wave envelopes are obtained. We examine how the behavior of rogue waves depends on the plasma parameters in question, finding that the rogue envelopes are lowered with increasing electron superthermality whereas the opposite is true when the plasma β increases. The findings of this study may find applications to low β plasmas in astrophysical environments where particles are superthermally distributed. * Electronic address: bbl@sdu.edu.cn Recently, Gogoi and Khan [37] studied the arbitrary amplitude kinetic Alfvén solitons using warm adiabatic ions and kappa-distributed electrons in a magnetized plasma. The system was shown to support compressive and double layer solutions, and it was demonstrated that the spectral index κ has significant effects on the shape and size of the solitary KAWs. Recently rogue waves have become of considerable interest in the broad areas of nonlinear fibre optics [39], optical systems [40, 41], atmospheric research [42] and plasmonics [43].Rogue waves are short-lived phenomena appearing suddenly out of normal waves. Excess

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Modulation of ion-acoustic waves in a nonextensive plasma with two-temperature electrons

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“…The experimental observations were compared with the theoretical findings determined from the solution of cubic NLSE and the Peregrine solitons were observed in triangular shape. Recent investigation of small amplitude solitary Kinetic Alfvén waves in low β plasmas with superthermal electrons has been done by Bains et al (2014). Rational solutions obtained from NLSE by extending KdV equation are examined to study the behavior of rogue waves.…”