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| Titel |
Nonlinear wave structures in collisional plasma of auroral E-region ionosphere |
| VerfasserIn |
A. V. Volosevich, Y. I. Galperin |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 15, no. 7 ; Nr. 15, no. 7, S.890-898 |
| Datensatznummer |
250012873
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| Publikation (Nr.) |
 copernicus.org/angeo-15-890-1997.pdf |
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| Zusammenfassung |
| Studies of the auroral plasma with
small-scale inhomogenieties producing the VHF-radar reflections (radar aurora)
when observed in conditions of the saturated Farley-Buneman instability within
the auroral E region, show strong nonlinear interactions and density
fluctuations of 5–15%. Such nonlinearity and high fluctation amplitudes are
inconsistent with the limitations of the weak turbulence theory, and thus a
theory for arbitrary amplitudes is needed. To this end, a nonlinear theory is
described for electrostatic MHD moving plasma structures of arbitrary amplitude
for conditions throughout the altitude range of the collisional auroral E
region. The equations are derived, from electron and ion motion self-consistent
with the electric field, for the general case of the one-dimensional problem.
They take into account nonlinearity, electron and ion inertia, diffusion,
deviation from quasi-neutrality, and dynamical ion viscosity. The importance of
the ion viscosity for dispersion is stressed, while deviation from the
quasi-neutrality can be important only at rather low plasma densities, not
typical for the auroral E region. In a small amplitude limit these equations
have classical nonlinear solutions of the type of "electrostatic shock
wave" or of knoidal waves. In a particular case these knoidal waves degrade
to a dissipative soliton. A two-dimensional case of a quasi-neutral plasma is
considered in the plane perpendicular to the magnetic field by way of the
Poisson brackets, but neglecting the nonlinearity and ion inertia. It is shown
that in these conditions an effective saturation can be achieved at the
stationary turbulence level of order of 10%. |
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