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| Titel |
Remarks on the parallel propagation of small-amplitude dispersive Alfvénic waves |
| VerfasserIn |
S. Champeaux, D. Laveder, T. Passot, P. L. Sulem |
| 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 ; 6, no. 3/4 ; Nr. 6, no. 3/4, S.169-178 |
| Datensatznummer |
250003221
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| Publikation (Nr.) |
 copernicus.org/npg-6-169-1999.pdf |
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| Zusammenfassung |
| The envelope formalism for the description of
a small-amplitude parallel-propagating Alfvén wave train is tested against
direct numerical simulations of the Hall-MHD equations in one space dimension
where kinetic effects are neglected. It turns out that the magnetosonic-wave
dynamics departs from the adiabatic approximation not only near the resonance
between the speed of sound and the Alfvén wave group velocity, but also when
the speed of sound lies between the group and phase velocities of the Alfvén
wave. The modulational instability then does not anymore affect asymptotically
large scales and strong nonlinear effects can develop even in the absence of the
decay instability. When the Hall-MHD equations are considered in the
long-wavelength limit, the weakly nonlinear dynamics is accurately reproduced by
the derivative nonlinear Schrödinger equation on the expected time scale,
provided no decay instabilities are present. The stronger nonlinear regime which
develops at later time is captured by including the coupling to the nonlinear
dynamics of the magnetosonic waves. |
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