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Title: Arbitrary amplitude fast electron-acoustic solitons in three-electron component space plasmas

Abstract

We examine the characteristics of fast electron-acoustic solitons in a four-component unmagnetised plasma model consisting of cool, warm, and hot electrons, and cool ions. We retain the inertia and pressure for all the plasma species by assuming adiabatic fluid behaviour for all the species. By using the Sagdeev pseudo-potential technique, the allowable Mach number ranges for fast electron-acoustic solitary waves are explored and discussed. It is found that the cool and warm electron number densities determine the polarity switch of the fast electron-acoustic solitons which are limited by either the occurrence of fast electron-acoustic double layers or warm and hot electron number density becoming unreal. For the first time in the study of solitons, we report on the coexistence of fast electron-acoustic solitons, in addition to the regular fast electron-acoustic solitons and double layers in our multi-species plasma model. Our results are applied to the generation of broadband electrostatic noise in the dayside auroral region.

Authors:
;  [1];  [2];  [3]; ;  [4];  [2]
  1. South African National Space Agency (SANSA) Space Science, P.O. Box 32, Hermanus 7200, Republic of South Africa (South Africa)
  2. (UWC), Robert Sobukwe Road, Bellville 7535, Republic of South Africa (South Africa)
  3. Department of Physics, University of the Western Cape (UWC), Robert Sobukwe Road, Bellville 7535, Republic of South Africa (South Africa)
  4. Indian Institute of Geomagnetism, New Panvel (West), Navi Mumbai 410218 (India)
Publication Date:
OSTI Identifier:
22598982
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 23; Journal Issue: 6; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; AMPLITUDES; DENSITY; ELECTRONS; FLUIDS; IONS; LAYERS; MACH NUMBER; MOMENT OF INERTIA; NOISE; PLASMA; SOLITONS; SPACE; SWITCHES

Citation Formats

Mbuli, L. N., Maharaj, S. K., Department of Physics, University of the Western Cape, Bharuthram, R., Singh, S. V., Lakhina, G. S., and Department of Physics, University of the Western Cape. Arbitrary amplitude fast electron-acoustic solitons in three-electron component space plasmas. United States: N. p., 2016. Web. doi:10.1063/1.4952637.
Mbuli, L. N., Maharaj, S. K., Department of Physics, University of the Western Cape, Bharuthram, R., Singh, S. V., Lakhina, G. S., & Department of Physics, University of the Western Cape. Arbitrary amplitude fast electron-acoustic solitons in three-electron component space plasmas. United States. doi:10.1063/1.4952637.
Mbuli, L. N., Maharaj, S. K., Department of Physics, University of the Western Cape, Bharuthram, R., Singh, S. V., Lakhina, G. S., and Department of Physics, University of the Western Cape. 2016. "Arbitrary amplitude fast electron-acoustic solitons in three-electron component space plasmas". United States. doi:10.1063/1.4952637.
@article{osti_22598982,
title = {Arbitrary amplitude fast electron-acoustic solitons in three-electron component space plasmas},
author = {Mbuli, L. N. and Maharaj, S. K. and Department of Physics, University of the Western Cape and Bharuthram, R. and Singh, S. V. and Lakhina, G. S. and Department of Physics, University of the Western Cape},
abstractNote = {We examine the characteristics of fast electron-acoustic solitons in a four-component unmagnetised plasma model consisting of cool, warm, and hot electrons, and cool ions. We retain the inertia and pressure for all the plasma species by assuming adiabatic fluid behaviour for all the species. By using the Sagdeev pseudo-potential technique, the allowable Mach number ranges for fast electron-acoustic solitary waves are explored and discussed. It is found that the cool and warm electron number densities determine the polarity switch of the fast electron-acoustic solitons which are limited by either the occurrence of fast electron-acoustic double layers or warm and hot electron number density becoming unreal. For the first time in the study of solitons, we report on the coexistence of fast electron-acoustic solitons, in addition to the regular fast electron-acoustic solitons and double layers in our multi-species plasma model. Our results are applied to the generation of broadband electrostatic noise in the dayside auroral region.},
doi = {10.1063/1.4952637},
journal = {Physics of Plasmas},
number = 6,
volume = 23,
place = {United States},
year = 2016,
month = 6
}
  • We examine the characteristics of large amplitude slow electron-acoustic solitons supported in a four-component unmagnetised plasma composed of cool, warm, hot electrons, and cool ions. The inertia and pressure for all the species in this plasma system are retained by assuming that they are adiabatic fluids. Our findings reveal that both positive and negative potential slow electron-acoustic solitons are supported in the four-component plasma system. The polarity switch of the slow electron-acoustic solitons is determined by the number densities of the cool and warm electrons. Negative potential solitons, which are limited by the cool and warm electron number densities becomingmore » unreal and the occurrence of negative potential double layers, are found for low values of the cool electron density, while the positive potential solitons occurring for large values of the cool electron density are only limited by positive potential double layers. Both the lower and upper Mach numbers for the slow electron-acoustic solitons are computed and discussed.« less
  • A three-component plasma model composed of ions, cool electrons, and hot electrons is adopted to investigate the existence of large amplitude electron-acoustic solitons not only for the model for which inertia and pressure are retained for all plasma species which are assumed to be adiabatic but also neglecting inertial effects of the hot electrons. Using the Sagdeev potential formalism, the Mach number ranges supporting the existence of large amplitude electron-acoustic solitons are presented. The limitations on the attainable amplitudes of electron-acoustic solitons having negative potentials are attributed to a number of different physical reasons, such as the number density ofmore » either the cool electrons or hot electrons ceases to be real valued beyond the upper Mach number limit, or, alternatively, a negative potential double layer occurs. Electron-acoustic solitons having positive potentials are found to be supported only if inertial effects of the hot electrons are retained and these are found to be limited only by positive potential double layers.« less
  • Using the Sagdeev pseudopotential technique, the existence of large amplitude ion-acoustic solitons is investigated for a plasma composed of ions, and hot and cool electrons. Not only are all species treated as adiabatic fluids but the model for which inertial effects of the hot electrons is neglected whilst retaining inertia and pressure for the ions and cool electrons has also been considered. The focus of this investigation has been on identifying the admissible Mach number ranges for large amplitude nonlinear ion-acoustic soliton structures. The lower Mach number limit yields a minimum velocity for the existence of ion-acoustic solitons. The uppermore » Mach number limit for positive potential solitons is found to coincide with the limiting value of the potential (positive) beyond which the ion number density ceases to be real valued, and ion-acoustic solitons can no longer exist. Small amplitude solitons having negative potentials are found to be supported when the temperature of the cool electrons is negligible.« less
  • No abstract prepared.
  • In a series of papers by Maharaj et al., including “Existence domains of slow and fast ion-acoustic solitons in two-ion space plasmas” [Phys. Plasmas 22, 032313 (2015)], incorrect expressions for the Sagdeev potential are presented. In this paper, we provide the correct expression of the Sagdeev potential. The correct expression was used to generate the numerical results for the above-mentioned series of papers, so that all results and conclusions are correct, despite the wrong Sagdeev potential expressions printed in the papers. The correct expression of the Sagdeev potential presented here is a very useful generic expression in the sense thatmore » a single expression can be used to study nonlinear structures associated with any acoustic mode, despite the fact that the supersonic and subsonic species would vary if solitons associated with different linear modes are studied.« less