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Title: Amplitude modulation of quantum-ion-acoustic wavepackets in electron-positron-ion plasmas: Modulational instability, envelope modes, extreme waves

A semirelativistic fluid model is employed to describe the nonlinear amplitude modulation of low-frequency (ionic scale) electrostatic waves in an unmagnetized electron-positron-ion 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 dark-type envelope solitons (voids, holes). The plasma configurational parameters (namely, the relativistic degeneracy parameter, the positron concentration, and the ionic temperature) are shown to affect the conditions for modulational instability significantly, in fact modifying the associated threshold as well as the instability growth rate. In particular, the relativistic degeneracy parameter leads to an enhancement of the modulational instability mechanism. Furthermore, the effect of different relevant plasma parameters on the characteristics (amplitude, width) of these envelope solitary structures is also presented in detail. Finally, the occurrence of extreme amplitude excitation (rogue waves) is also discussed briefly. Our results aim at elucidating the formation and dynamics of nonlinear electrostatic excitations in superdensemore » astrophysical regimes.« less
Authors:
 [1] ;  [2] ; ;  [3] ;  [4] ;  [5] ;  [1]
  1. Department of Physics, University of Peshawar, Peshawar 25000 (Pakistan)
  2. (Pakistan)
  3. Centre for Plasma Physics, Department of Physics and Astronomy, Queen's University Belfast, BT7 1NN Northern Ireland (United Kingdom)
  4. Department of Physics, Faculty of Science, Damietta University, New Damietta, P.O. Box 34517 (Egypt)
  5. (Saudi Arabia)
Publication Date:
OSTI Identifier:
22408088
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 22; Journal Issue: 2; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; AMPLITUDES; ASTROPHYSICS; ELECTRONS; EXCITATION; FREQUENCY MODULATION; INSTABILITY GROWTH RATES; IONS; NONLINEAR PROBLEMS; PERTURBATION THEORY; PLASMA WAVES; POSITRONS; QUANTUM PLASMA; RELATIVISTIC RANGE; SCHROEDINGER EQUATION; SOLITONS; WAVE PACKETS