Nonlinear propagation of ion-acoustic waves in an electron-positron-ion plasma (original) (raw)
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Journal of Plasma Physics, 2013
The dynamics and propagation of ion acoustic (IA) waves are considered in an unmagnetized collisionless plasma, whose constituents are the relativistically degenerate electrons and positrons as well as the inertial cold ions. At a first step, a linear dispersion relation for IA waves is derived and analysed numerically. For nonlinear analysis, the reductive perturbation technique is used to derive a Korteweg–deVries equation, which admits a localized wave solution in the presence of relativistic degenerate electrons and positrons. It is shown that only compressive IA solitary waves can propagate, whose amplitude, width and phase velocity are significantly modified due to the positron concentration. The latter also strongly influences all the relativistic plasma parameters. Our present analysis is aimed to understand collective interactions in dense astrophysical objects, e.g. white dwarfs, where the lighter species electrons and positrons are taken as relativistically degenerate.
The nonlinear propagation of dust ion-acoustic (DIA) waves in a unmagnetized collisionless degenerate dense plasma (containing degenerate electron and positron, and classical ion fluids) has been theoretically investigated. The K-dV equation has been derived by employing the reductive perturbation method and by taking into account the effect of different plasma parameters in plasma fluid. The stationary solitary wave solution of K-dV equation is obtained, and numerically analyzed to identify the basic properties of DIA solitary structures. It has been shown that depending on plasma parametric values, the degenerate plasma under consideration supports compressive or rarefactive solitary structures. It has been also found that the effect of pressures on electrons, ions, and positrons significantly modify the basic features of solitary waves that are found to exist in such a plasma system. The relevance of our results in astrophysical objects such as white dwarfs and neutron stars, which are of scientific interest, is discussed briefly.
Czechoslovak Journal of Physics, 2004
A rigorous theoretical investigation has been made of arbitrary amplitude compressive and rarefactive ion acoustic solitary waves in three component plasmas, consisting of ions, positrons and non-thermally distributed electrons. The pseudo-potential approach, which is valid for large amplitude solitary waves and the reductive perturbation technique for small amplitude solitary waves, have been employed. It is shown from both weakly and highly nonlinear analyses that the presence of the fast or non-thermal electrons may allow compressive and rarefactive solitary waves to coexist. It is found that the effect of the positron density changes the minimum value of α (a parameter determining the number of fast electrons present in our model) and M (the Mach number) for which the compressive and rarefactive solitary waves can coexist. The present theory is applicable to analyse arbitrary amplitude ion acoustic waves associated with positrons which may occur in space plasmas.
Journal of Plasma Physics, 2012
Arbitrary amplitude and small amplitude ion-acoustic solitary waves (IASWs) have been investigated in a relativistic, collisionless, unmagnetized, and degenerate dense electron–positron–ion plasma. The arbitrary amplitude IASWs have been studied by using the Sagdeev-type pseudo-potential approach. Along with approximate solution, the exact amplitude solitary structure has also been studied numerically. The electrons and positrons are assumed to follow the corresponding Fermi distribution function and the ions are described by the hydrodynamic equations. A new dispersion relation for the ion-acoustic wave has been derived for the relativistic Thomas–Fermi plasma. An energy balance-like equation involving the Sagdeev-type pseudo-potential has been investigated and it has been shown that the concentration of plasma particles has significant effect on the permitted Mach number range of IASWs. Also, it has been pointed out that the only compressional supersonic IASWs can propagate in the...
Astrophysics and Space Science, 2015
A precise theoretical investigation has been made on electron-acoustic (EA) Gardner solitons (GSs) and double layers (DLs) in a four-component plasma system consisting of nonextensive hot electrons and positrons, inertial cold electrons, and immobile positive ions. The well-known reductive perturbation method has been used to derive the Korteweg-de Vries (K-dV), modified K-dV (mK-dV), and Gardner equations along with their solitary wave as well as double layer solutions. It has been found that depending on the plasma parameters, the K-dV solitons and GSs are either compressive or rarefactive, whereas the mK-dV solitons are only compressive, and Gardner DLs are only rarefactive. The analytical comparison among the K-dV solitons, mK-dV solitons, and GSs are also investigated. It has been identified that the basic properties of such EA solitons and EA DLs are significantly modified due to the effects of nonextensivity and other plasma parameters related to plasma particle number densities and to temperature of different plasma species. The results of our present investigation can be helpful for understanding the nonlinear electrostatic structures associated with EA waves in various interstellar space plasma environments and cosmological scenarios (viz. quark-gluon plasma, protoneutron stars, stellar polytropes, hadronic matter, dark-matter halos, etc.) Keywords Electron-acoustic waves • Nonextensive electrons and positrons • Electron-positron-ion plasmas • Gardner solitons and DLs B A. Rafat
International Journal of Applied and Computational Mathematics, 2019
Based on reductive perturbation theory, the nonlinear structure of non-extensive multispecies plasma containing hot electrons, adiabatic cold electrons, cold positrons and ions has been investigated via different nonlinear KdV, mKdV and Gardner's equations. It is shown that the formation and properties of electron acoustic solitary waves and double-layer can exist in such plasma system depending on some relevant physical parameters such as electron and positron density ratios, electrons temperatures ratio and non-extensive parameter. The existence conditions of these types of waves are extensively discussed. The obtained results may be useful in improving and understanding the propagation of the nonlinear electron waves in space plasma, Earth's magnetosphere and solar wind.
Electrostatic Solitary Waves in Relativistic Degenerate Electron–Positron–Ion Plasma
IEEE Transactions on Plasma Science, 2015
The linear and nonlinear properties of ion acoustic excitations propagating in warm dense electron-positron-ion plasma are investigated. Electrons and positrons are assumed relativistic and degenerate, following the Fermi-Dirac statistics, whereas the warm ions are described by a set of classical fluid equations. A linear dispersion relation is derived in the linear approximation. Adopting a reductive perturbation method, the Korteweg-de Vries equation is derived, which admits a localized wave solution in the form of a small-amplitude weakly super-acoustic pulse-shaped soliton. The analysis is extended to account for arbitrary amplitude solitary waves, by deriving a pseudoenergy-balance like equation, involving a Sagdeev-type pseudopotential. It is shown that the two approaches agree exactly in the small-amplitude weakly super-acoustic limit. The range of allowed values of the pulse soliton speed (Mach number), wherein solitary waves may exist, is determined. The effects of the key plasma configuration parameters, namely, the electron relativistic degeneracy parameter, the ion (thermal)-to-the electron (Fermi) temperature ratio, and the positron-to-electron density ratio, on the soliton characteristics and existence domain, are studied in detail. Our results aim at elucidating the characteristics of ion acoustic excitations in relativistic degenerate plasmas, e.g., in dense astrophysical objects, where degenerate electrons and positrons may occur. Index Terms-Plasma oscillations, plasma waves. I. INTRODUCTION R ECENTLY there has been a great deal of interest in elucidating the dynamics of collective processes in degenerate dense plasmas, commonly found in dense astrophysical objects (e.g., white and brown dwarfs, neutron stars, and magnetars), in the core of giant planets (e.g., Jovian planets), which can Manuscript
Nonlinear propagation of weakly relativistic ion-acoustic waves in electron–positron–ion plasma
Pramana, 2016
This work presents theoretical and numerical discussion on the dynamics of ion-acoustic solitary wave for weakly relativistic regime in unmagnetized plasma comprising non-extensive electrons, Boltzmann positrons and relativistic ions. In order to analyse the nonlinear propagation phenomena, the Korteweg-de Vries (KdV) equation is derived using the well-known reductive perturbation method. The integration of the derived equation is carried out using the ansatz method and the generalized Riccati equation mapping method. The influence of plasma parameters on the amplitude and width of the soliton and the electrostatic nonlinear propagation of weakly relativistic ion-acoustic solitary waves are described. The obtained results of the nonlinear low-frequency waves in such plasmas may be helpful to understand various phenomena in astrophysical compact object and space physics.
Positron acoustic solitary waves interaction in a four-component space plasma
Astrophysics and Space Science, 2012
The characteristics of the head-on collision (HOC) between two positron acoustic solitary waves (PASWs) in a four component electron-positron-ion (EPI) space plasma have been investigated theoretically, using the extended Poincaré-Lighthill-Kuo (PLK) method. The analytical phase shifts after the collision of the two solitary waves occurs are derived. Numerically, the influences of the cold/hot positron parameters on the phase shifts are explicitly investigated. The present theory is applied to analyze the formation and the interaction of localized coherent PASWs structures in space plasmas (pulsar environments).