Oblique modulation of electrostatic modes and envelope excitations in pairion and electronpositron plasmas
Abstract
The nonlinear amplitude modulation of electrostatic waves propagating in a collisionless twocomponent plasma consisting of negative and positive species of equal mass and absolute charge is investigated. Pairion (e.g., fullerene) and electronpositron (ep) plasmas (neglecting recombination) are covered by this description. Amplitude perturbation oblique to the direction of propagation of the wave has been considered. Two distinct linear electrostatic modes exist, namely an acoustic lower mode and Langmuirtype optictype upper one. The behavior of each of these modes is examined from the modulational stability point of view. The stability criteria are investigated, depending on the electrostatic carrier wave number, the angle {theta} between the modulation and propagation directions, and the positrontoelectron temperature ratio {sigma}. The analysis shows that modulated electrostatic wavepackets associated to the lower (acoustic) mode are unstable, for small values of carrier wave number k (i.e., for large wavelength {lambda}) and for finite (small) values of the angle {theta} (yet stable for higher {theta}), while those related to the upper (opticlike) mode are stable for large values of the angle {theta} only, in the same limit, yet nearly for all values of {sigma}. These results are of relevance in astrophysical contexts (e.g., in pulsar environments), where ep plasmasmore »
 Authors:
 Azarbaijan University of Tarbiat Moallem, Faculty of Science, Department of Physics, 51745406, Tabriz (Iran, Islamic Republic of)
 (Germany) and Universiteit Gent, Sterrenkundig Observatorium, Krijgslaan 281, B9000 Gent (Belgium)
 (Germany)
 Publication Date:
 OSTI Identifier:
 20860434
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Physics of Plasmas; Journal Volume: 13; Journal Issue: 12; Other Information: DOI: 10.1063/1.2405328; (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; DISTURBANCES; ELECTRON TEMPERATURE; ELECTRONS; EXCITATION; FULLERENES; ION ACOUSTIC WAVES; ION TEMPERATURE; IONS; MODULATION; NONLINEAR PROBLEMS; PLASMA; PLASMA INSTABILITY; POSITRONS; PULSARS; RADIATION TRANSPORT; STABILITY; WAVE PACKETS
Citation Formats
EsfandyariKalejahi, A., Kourakis, I., Shukla, P. K., RuhrUniversitaet Bochum, Fakultaet fuer Physik und Astronomie, Institut fuer Theoretische Physik IV, D44780 Bochum, and RuhrUniversitaet Bochum, Fakultaet fuer Physik und Astronomie, Institut fuer Theoretische Physik IV, D44780 Bochum. Oblique modulation of electrostatic modes and envelope excitations in pairion and electronpositron plasmas. United States: N. p., 2006.
Web. doi:10.1063/1.2405328.
EsfandyariKalejahi, A., Kourakis, I., Shukla, P. K., RuhrUniversitaet Bochum, Fakultaet fuer Physik und Astronomie, Institut fuer Theoretische Physik IV, D44780 Bochum, & RuhrUniversitaet Bochum, Fakultaet fuer Physik und Astronomie, Institut fuer Theoretische Physik IV, D44780 Bochum. Oblique modulation of electrostatic modes and envelope excitations in pairion and electronpositron plasmas. United States. doi:10.1063/1.2405328.
EsfandyariKalejahi, A., Kourakis, I., Shukla, P. K., RuhrUniversitaet Bochum, Fakultaet fuer Physik und Astronomie, Institut fuer Theoretische Physik IV, D44780 Bochum, and RuhrUniversitaet Bochum, Fakultaet fuer Physik und Astronomie, Institut fuer Theoretische Physik IV, D44780 Bochum. Fri .
"Oblique modulation of electrostatic modes and envelope excitations in pairion and electronpositron plasmas". United States.
doi:10.1063/1.2405328.
@article{osti_20860434,
title = {Oblique modulation of electrostatic modes and envelope excitations in pairion and electronpositron plasmas},
author = {EsfandyariKalejahi, A. and Kourakis, I. and Shukla, P. K. and RuhrUniversitaet Bochum, Fakultaet fuer Physik und Astronomie, Institut fuer Theoretische Physik IV, D44780 Bochum and RuhrUniversitaet Bochum, Fakultaet fuer Physik und Astronomie, Institut fuer Theoretische Physik IV, D44780 Bochum},
abstractNote = {The nonlinear amplitude modulation of electrostatic waves propagating in a collisionless twocomponent plasma consisting of negative and positive species of equal mass and absolute charge is investigated. Pairion (e.g., fullerene) and electronpositron (ep) plasmas (neglecting recombination) are covered by this description. Amplitude perturbation oblique to the direction of propagation of the wave has been considered. Two distinct linear electrostatic modes exist, namely an acoustic lower mode and Langmuirtype optictype upper one. The behavior of each of these modes is examined from the modulational stability point of view. The stability criteria are investigated, depending on the electrostatic carrier wave number, the angle {theta} between the modulation and propagation directions, and the positrontoelectron temperature ratio {sigma}. The analysis shows that modulated electrostatic wavepackets associated to the lower (acoustic) mode are unstable, for small values of carrier wave number k (i.e., for large wavelength {lambda}) and for finite (small) values of the angle {theta} (yet stable for higher {theta}), while those related to the upper (opticlike) mode are stable for large values of the angle {theta} only, in the same limit, yet nearly for all values of {sigma}. These results are of relevance in astrophysical contexts (e.g., in pulsar environments), where ep plasmas are encountered, or in pair fullereneion plasmas, in laboratory.},
doi = {10.1063/1.2405328},
journal = {Physics of Plasmas},
number = 12,
volume = 13,
place = {United States},
year = {Fri Dec 15 00:00:00 EST 2006},
month = {Fri Dec 15 00:00:00 EST 2006}
}

A semirelativistic fluid model is employed to describe the nonlinear amplitude modulation of lowfrequency (ionic scale) electrostatic waves in an unmagnetized electronpositronion plasma. Electrons and positrons are assumed to be degenerated and inertialess, whereas ions are warm and classical. A multiscale perturbation method is used to derive a nonlinear Schrödinger equation for the envelope amplitude, based on which the occurrence of modulational instability is investigated in detail. Various types of localized ion acoustic excitations are shown to exist, in the form of either bright type envelope solitons (envelope pulses) or darktype envelope solitons (voids, holes). The plasma configurational parameters (namely,more »

Modulated electrostatic modes in pair plasmas: Modulational stability profile and envelope excitations
A pair plasma consisting of two types of ions, possessing equal masses and opposite charges, is considered. The nonlinear propagation of modulated electrostatic wave packets is studied by employing a twofluid plasma model. Considering propagation parallel to the external magnetic field, two distinct electrostatic modes are obtained, namely a quasiacoustic lower moddfe and a Langmuirlike, as optictype upper one, in agreement with experimental observations and theoretical predictions. Considering small yet weakly nonlinear deviations from equilibrium, and adopting a multiplescale technique, the basic set of model equations is reduced to a nonlinear Schroedinger equation for the slowly varying electric field perturbationmore » 
Oblique modulation of ionacoustic waves and envelope solitons in electronpositronion plasma
The effect of oblique modulation on the amplitude dynamics of ionacoustic wave propagating in a collisionless electronpositronion plasma is investigated. Using KrylovBogoliubovMitropolsky (KBM) perturbation method, a nonlinear Schroedinger (NLS) equation is derived which governs the evolution of obliquely modulated ionacoustic envelope excitations. It is found that the presence of positron component significantly modifies the stability domains for small angles of propagation with the direction of modulation. The stationary solutions of NLS equation, i.e., bright and dark envelope solitons, become narrower as the concentration of positron component increases. 
Effect of nonthermal electrons on oblique electrostatic excitations in a magnetized electronpositronion plasma
The linear and nonlinear propagation of ionacoustic waves are investigated in a magnetized electronpositronion (epi) plasma with nonthermal electrons. In the linear regime, the propagation of two possible modes and their evolution are studied via a dispersion relation. In the cases of parallel and perpendicular propagation, it is shown that these two possible modes are always stable. Then, the Kortewegde Vries equation describing the dynamics of ionacoustic solitary waves is derived from a weakly nonlinear analysis. The influence on the solitary wave characteristics of relevant physical parameters such as nonthermal electrons, magnetic field, obliqueness, positron concentration, and temperature ratio ismore »