Modulational Instability, Ion-Acoustic Envelope Solitons, and Rogue Waves in Four-Component Plasmas
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Modulational Instability, Ion-Acoustic Envelope Solitons, and Rogue Waves in Four-Component Plasmas1 N. A. Chowdhurya,*, A. Mannana, M. M. Hasana, and A. A. Mamuna a Department
of Physics, Jahangirnagar University, Savar, Dhaka-1342, Bangladesh *e-mail: [email protected]
Received August 14, 2018; revised October 8, 2018; accepted October 25, 2018
Abstract—Modulational instability (MI) of ion-acoustic waves (IAWs) has been theoretically investigated in a plasma system which is composed of inertial warm adiabatic ions, isothermal positrons, and two-temperature super-thermal electrons (cool and hot). A nonlinear Schrödinger equation (NLSE) is derived by using reductive perturbation method that governs the MI of the IAWs. The numerical analysis of the solution of NLSE shows the existence of both stable (dark envelope solitons) and unstable (bright envelope solitons and rogue waves) regimes of IAWs. It is observed that the basic features (viz., stability of the wave profile and MI growth rate) of the IAWs are significantly modified by the superthermality of electrons and related plasma parameters. The results of our present investigation should be useful for understanding different nonlinear phenomena in both space (viz., Saturn’s magnetosphere and interplanetary medium) and laboratory plasmas (viz., hot-cathode discharge and high-intensity laser irradiation). DOI: 10.1134/S1063780X19050027
1. INTRODUCTION During the last few decades, research regarding electron–positron–ion (e–p–i) plasma has been spectacularly increased, because the observational (viz., Viking satellite [1] and Themis mission [2]) results have exposed the existence of large amount of e–p–i plasma in the space, namely, Saturn’s magnetosphere [3], pulsar magnetosphere [4], and laboratories plasmas [5]. Many authors have encountered with wave dynamics [6–9], viz., electron-acoustic waves (EAWs), positron-acoustic waves, ion-acoustic (IA) waves (IAWs), and IA rogue waves (IARWs), to understand the physics of collective behavior in such kind of space and laboratory plasmas. Highly energetic particles may coexist with isothermally distributed particles in space and laboratory plasmas and their characteristics are deviated from the Maxwellian distribution. Sometimes, these energetic particles may be governed by non-Maxwellian highenergy tail distribution, which is known as generalized Lorentzian or kappa (κ) distribution [10–12]. The κdistribution and its relation to the Maxwellian distribution were first introduced by Vasylinuas [10]. This type of distribution may arise due to the external forces acting on the natural space plasmas or wave–particle interaction. The Lorentzian or κ-distribution function reduces to the Maxwellian for the limit of large spectral index [11], i.e., κ → ∞ . A lot of works have done by considering single-temperature super-thermal 1 The article is published in the original.
electrons in plasma model [7, 12]. But in space, as well as in laboratory plasmas, electrons are found to have two distinct tempera
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