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Title: High and low frequency instabilities driven by counter-streaming electron beams in space plasmas

A four-component plasma composed of a drifting (parallel to ambient magnetic field) population of warm electrons, drifting (anti-parallel to ambient magnetic field) cool electrons, stationary hot electrons, and thermal ions is studied in an attempt to further our understanding of the excitation mechanisms of broadband electrostatic noise (BEN) in the Earth's magnetospheric regions such as the magnetosheath, plasmasphere, and plasma sheet boundary layer (PSBL). Using kinetic theory, beam-driven electrostatic instabilities such as the ion-acoustic, electron-acoustic instabilities are found to be supported in our multi-component model. The dependence of the instability growth rates and real frequencies on various plasma parameters such as beam speed, number density, temperature, and temperature anisotropy of the counter-streaming (relative to ambient magnetic field) cool electron beam are investigated. It is found that the number density of the anti-field aligned cool electron beam and drift speed play a central role in determining which instability is excited. Using plasma parameters which are closely correlated with the measurements made by the Cluster satellites in the PSBL region, we find that the electron-acoustic and ion-acoustic instabilities could account for the generation of BEN in this region.
Authors:
 [1] ;  [2] ;  [1] ;  [3]
  1. South African National Space Agency (SANSA) Space Science, P.O. Box 32, Hermanus 7200, Republic of South Africa (South Africa)
  2. (South Africa)
  3. University of the Western Cape, Robert Sobukwe Road, Bellville 7535, Republic of South Africa (South Africa)
Publication Date:
OSTI Identifier:
22300126
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 5; Other Information: (c) 2014 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; BOUNDARY LAYERS; ELECTRON BEAMS; ELECTRON DRIFT; ELECTRONS; INSTABILITY GROWTH RATES; MAGNETIC FIELDS; MAGNETOSHEATH; PLASMA; PLASMA SHEET; PLASMASPHERE