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| Titel |
Nongyrotropy in magnetoplasmas: simulation of wave excitation and phase-space diffusion |
| VerfasserIn |
U. Motschmann, H. Kafemann, M. Scholer |
| 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. 6 ; Nr. 15, no. 6, S.603-613 |
| Datensatznummer |
250012820
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| Publikation (Nr.) |
 copernicus.org/angeo-15-603-1997.pdf |
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| Zusammenfassung |
| Nongyrotropic (gyrophase bunched) ion
distributions in a magnetoplasma are studied by analytical methods and by
two-dimensional hybrid code simulations. Nongyrotropy may not occur in a plasma
being simultaneously homogeneous, stationary, and solenoidal in phase space. A
detailed study is performed for a homogeneous and stationary plasma with sources
and sinks in phase space. The analytical investigation cast in the framework of
linearized Maxwell-Vlasov theory yields a coupling of low-frequency left-handed,
right-handed, and longitudinal modes. Nongyrotropic ion distributions are
unstable; they excite left-handed waves. The growth rate is comparable to that
of the ion ring instability. The hybrid code simulation study confirms the
expected propagation direction parallel to the background magnetic field. Three
diffusion processes are studied: arc lengthening, arc broadening, and arc radius
decreasing corresponding to particle energy diffusion. The characteristic
diffusion time-scales are found to be of the order of 101 wave
cycles. |
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