Compressive and Rarefactive Electron-Acoustic Solitons and Double Layers in Space Plasmas |
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Authors: | Frank Verheest Tom Cattaert Manfred A Hellberg |
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Institution: | (1) Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281, B-9000 Gent, Belgium;(2) School of Physics (Howard College Campus), University of KwaZulu-Natal, Durban, 4041, South Africa |
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Abstract: | Space observations in several near-Earth environments have revealed the presence of positive-potential, large-amplitude electrostatic
structures, associated with high-frequency disturbances, and indicative of electron dynamics. Earlier models proposed in terms
of electron-acoustic solitary waves in a two-electron-temperature plasma were inadequate, because only negative potential
structures could thus be obtained, whereas the observations point to positive potential structures. In this paper, it is shown
that the theoretical restriction to negative potential solitons is due to the neglect of the inertia of the hot electrons,
implicitly or explicitly assumed in previous papers. If hot electron inertia is retained, however, there exists a parameter
range where positive potential solitary waves are formed, which can have important consequences for the re-interpretation
of several astrophysical phenomena involving two-electron-temperature plasmas.
PACS: 52.35.Mw, 52.35.Sb, 96.50.Ry |
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Keywords: | electron-acoustic modes magnetosphere auroral plasmas |
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