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| Titel |
Model of strong stationary vortex turbulence in space plasmas |
| VerfasserIn |
G. D. Aburjania, Kh. Z. Chargazia, L. M. Zelenyi, G. Zimbardo |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1023-5809
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| Digitales Dokument |
URL |
| Erschienen |
In: Nonlinear Processes in Geophysics ; 16, no. 1 ; Nr. 16, no. 1 (2009-01-22), S.11-22 |
| Datensatznummer |
250013083
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| Publikation (Nr.) |
 copernicus.org/npg-16-11-2009.pdf |
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| Zusammenfassung |
| This paper investigates the macroscopic consequences of nonlinear solitary
vortex structures in magnetized space plasmas by developing theoretical
model of plasma turbulence. Strongly localized vortex patterns contain
trapped particles and, propagating in a medium, excite substantial
density fluctuations and thus, intensify the energy, heat and mass transport
processes, i.e., such vortices can form strong vortex turbulence. Turbulence
is represented as an ensemble of strongly localized (and therefore weakly
interacting) vortices. Vortices with various amplitudes are randomly
distributed in space (due to collisions). For their description, a
statistical approach is applied. It is supposed that a stationary turbulent
state is formed by balancing competing effects: spontaneous development of
vortices due to nonlinear twisting of the perturbations' fronts, cascading
of perturbations into short scales (direct spectral cascade) and collisional
or collisionless damping of the perturbations in the short-wave domain. In
the inertial range, direct spectral cascade occurs through merging
structures via collisions. It is shown that in the magneto-active plasmas,
strong turbulence is generally anisotropic Turbulent modes mainly develop in
the direction perpendicular to the local magnetic field. It is found that it
is the compressibility of the local medium which primarily determines the
character of the turbulent spectra: the strong vortex turbulence forms a
power spectrum in
wave number space. For example, a new spectrum of turbulent fluctuations
in k−8/3 is derived which agrees with available experimental data.
Within the framework of the developed model particle diffusion processes are
also investigated. It is found that the interaction of structures with each
other and particles causes anomalous diffusion in the medium. The effective
coefficient of diffusion has a square root dependence on the stationary
level of noise. |
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