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Title: Nonlinear propagation of ion-acoustic waves in electron-positron-ion plasma with trapped electrons

Abstract

A theoretical investigation has been made for ion-acoustic waves in an unmagnetized electron-positron-ion plasma. A more realistic situation in which plasma consists of a negatively charged ion fluid, free positrons, and trapped as well as free electrons is considered. The properties of stationary structures are studied by the reductive perturbation method, which is valid for small but finite amplitude limit, and by pseudopotential approach, which is valid for large amplitude. With an appropriate modified form of the electron number density, two new equations for the ion dynamics have been found. When deviations from isothermality are finite, the modified Korteweg-deVries equation has been found, and for the case that deviations from isothermality are small, calculations lead to a generalized Korteweg-deVries equation. It is shown from both weakly and highly nonlinear analysis that the presence of the positrons may allow solitary waves to exist. It is found that the effect of the positron density changes the maximum value of the amplitude and M (Mach number) for which solitary waves can exist. The present theory is applicable to analyze arbitrary amplitude ion-acoustic waves associated with positrons which may occur in space plasma.

Authors:
; ;  [1];  [2]
  1. Faculty of Physics, Tabriz University, Tabriz 51664 (Iran, Islamic Republic of)
  2. (Iran, Islamic Republic of)
Publication Date:
OSTI Identifier:
20782435
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 13; Journal Issue: 1; Other Information: DOI: 10.1063/1.2158148; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; AMPLITUDES; ELECTRON DENSITY; ION ACOUSTIC WAVES; IONS; KORTEWEG-DE VRIES EQUATION; MACH NUMBER; NONLINEAR PROBLEMS; PERTURBATION THEORY; PLASMA; PLASMA DENSITY; POSITRONS; SOLITONS; TRAPPED ELECTRONS; TRAPPING

Citation Formats

Alinejad, H., Sobhanian, S., Mahmoodi, J., and Physics Department, University of Qom, Qom. Nonlinear propagation of ion-acoustic waves in electron-positron-ion plasma with trapped electrons. United States: N. p., 2006. Web. doi:10.1063/1.2158148.
Alinejad, H., Sobhanian, S., Mahmoodi, J., & Physics Department, University of Qom, Qom. Nonlinear propagation of ion-acoustic waves in electron-positron-ion plasma with trapped electrons. United States. doi:10.1063/1.2158148.
Alinejad, H., Sobhanian, S., Mahmoodi, J., and Physics Department, University of Qom, Qom. Sun . "Nonlinear propagation of ion-acoustic waves in electron-positron-ion plasma with trapped electrons". United States. doi:10.1063/1.2158148.
@article{osti_20782435,
title = {Nonlinear propagation of ion-acoustic waves in electron-positron-ion plasma with trapped electrons},
author = {Alinejad, H. and Sobhanian, S. and Mahmoodi, J. and Physics Department, University of Qom, Qom},
abstractNote = {A theoretical investigation has been made for ion-acoustic waves in an unmagnetized electron-positron-ion plasma. A more realistic situation in which plasma consists of a negatively charged ion fluid, free positrons, and trapped as well as free electrons is considered. The properties of stationary structures are studied by the reductive perturbation method, which is valid for small but finite amplitude limit, and by pseudopotential approach, which is valid for large amplitude. With an appropriate modified form of the electron number density, two new equations for the ion dynamics have been found. When deviations from isothermality are finite, the modified Korteweg-deVries equation has been found, and for the case that deviations from isothermality are small, calculations lead to a generalized Korteweg-deVries equation. It is shown from both weakly and highly nonlinear analysis that the presence of the positrons may allow solitary waves to exist. It is found that the effect of the positron density changes the maximum value of the amplitude and M (Mach number) for which solitary waves can exist. The present theory is applicable to analyze arbitrary amplitude ion-acoustic waves associated with positrons which may occur in space plasma.},
doi = {10.1063/1.2158148},
journal = {Physics of Plasmas},
number = 1,
volume = 13,
place = {United States},
year = {Sun Jan 15 00:00:00 EST 2006},
month = {Sun Jan 15 00:00:00 EST 2006}
}
  • The oblique propagation of ion-acoustic soliton-cnoidal waves in a magnetized electron-positron-ion plasma with superthermal electrons is studied. Linear dispersion relations of the fast and slow ion-acoustic modes are discussed under the weak and strong magnetic field situations. By means of the reductive perturbation approach, Korteweg-de Vries equations governing ion-acoustic waves of fast and slow modes are derived, respectively. Explicit interacting soliton-cnoidal wave solutions are obtained by the generalized truncated Painlevé expansion. It is found that every peak of a cnoidal wave elastically interacts with a usual soliton except for some phase shifts. The influence of the electron superthermality, positron concentration,more » and magnetic field obliqueness on the soliton-cnoidal wave are investigated in detail.« less
  • Ion-acoustic (IA) solitary waves are investigated in a magnetized three-component plasma consisting of cold ions, isothermal hot electrons, and positrons. The basic set of fluid equations is reduced to the Korteweg de Vries equation using the standard reductive perturbation (multiple-scale) technique. Theoretical and numerical analyses confirm significant effects of the presence of positrons and the dependence of the electron to positron temperature ratio on the amplitude and the width of IA solitary waves. It is shown that the rarefactive and compressive IA solitary excitations can propagate when the propagation angle {theta} satisfies 0{<=}{theta}<{pi}/2 and {pi}/2<{theta}{<=}{pi}, respectively. Also, it is remarkedmore » that the amplitude of the rarefactive and compressive IA solitary excitations is not affected by the magnitude of external magnetic field B{sub 0}, whereas their width depends strictly on B{sub 0}. The numerical analysis has been done based on the typical numerical data from a pulsar magnetosphere.« less
  • Effects of superthermal and trapped electrons on the oblique propagation of linear and nonlinear ion-acoustic waves in an electron-ion plasma in the presence of a uniform external magnetic field are investigated. In order to model the superthermal electrons, a Lorentzian (kappa) velocity distribution function has been employed. The ions are cold and their dynamics are studied by hydrodynamic equations. First, the linear dispersion relation of the fast and slow modes are obtained. It is shown that the superthermal electrons cause the both modes to propagate with smaller phase velocities. Then, modified Korteweg-de Vries equations describing the propagation of nonlinear slowmore » and fast ion-acoustic waves are derived. It is shown that the presence of superthermal and trapped electrons has great influence on the nature of magnetized ion-acoustic solitons. The dependency of soliton attributes to the parameters associated with the superthermality and trapping mechanism will be shown.« less
  • The properties of obliquely propagating ion-acoustic solitary waves in the presence of ambient magnetic field have been investigated theoretically in an electron-positron-ion nonthermal plasma. The plasma nonthermality is introduced via the q-nonextensive distribution of electrons and positrons. The Korteweg-de Vries (K-dV) and modified K-dV (mK-dV) equations are derived by adopting reductive perturbation method. The solution of K-dV and modified K-dV equation, which describes the solitary wave characteristics in the long wavelength limit, is obtained by steady state approach. It is seen that the electron and positron nonextensivity and external magnetic field (obliqueness) have significant effects on the characteristics of solitarymore » waves. A critical value of nonextensivity is found for which solitary structures transit from positive to negative potential. The findings of this investigation may be used in understanding the wave propagation in laboratory and space plasmas where static external magnetic field is present.« less
  • The purpose of this work is to investigate the linear and nonlinear properties of the ion-acoustic waves (IAW), propagating obliquely to an external magnetic field in a weakly relativistic, rotating, and magnetized electron-positron-ion plasma. The Zakharov-Kuznetsov equation is derived by employing the reductive perturbation technique for this wave in the nonlinear regime. This equation admits the solitary wave solution. The amplitude and width of this solitary wave have been discussed with the effects of obliqueness, relativity, ion temperature, positron concentration, magnetic field, and rotation of the plasma and it is observed that for IAW these parameters affect the propagation propertiesmore » of solitary waves and these plasmas behave differently from the simple electron-ion plasmas. Likewise, the current density and electric field of these waves are investigated for their dependence on the above-mentioned parameters.« less