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| Titel |
MHD simulations of the flapping instability in tail-like magnetic configurations with guide field |
| VerfasserIn |
Daniil Korovinskiy, Andrey Divin, Ivan Ivanov, Vladimir Semenov, Nikolay Erkaev, Anton Artemiev, Stefano Markidis, Giovanni Lapenta, Viktoria Ivanova, Darya Kubyshkina |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250097994
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| Publikation (Nr.) |
 EGU/EGU2014-13628.pdf |
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| Zusammenfassung |
| The flapping (kink) mode developing in the magnetotail-like magnetic configuration with
tailward growing normal magnetic component and finite guide field is studied by means of
linearized 2-dimensional and non-linear 3-dimensional MHD modeling. We consider a
particular case of a weak normal magnetic component (that is, small radius of the magnetic
field line curvature), which makes the configuration unstable to a special branch of ballooning
instability known as "double-gradient" mode, introduced recently to describe the magnetotail
flapping oscillations. The initial tail-like equilibrium is provided by conventional
Grad-Shafranov equation. The results of the 2D linearized MHD code are in agreement with
the analytical predictions, and the growth rate is found to be close to the peak value
provided by an analytical estimate. Both 2D and 3D calculations confirm that the
double-gradient mode is excited in a region of large curvature of the magnetic field lines. In
agreement with the analytical predictions, non-zero guide field reduces the growth rate
significantly for large (compare to the current sheet width L) wave numbers k, hence the
modes kL ~ 1 are the fastest growing. Thus, the non-zero guide field introduces
a characteristic wavelength corresponding to the dispersion curve peak. For the
guide field of ~ 0.5 (in the lobe magnetic field units), the mode decays totally. |
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