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| Titel |
Three-dimensional simulation of the electromagnetic ion/ion beam instability: cross field diffusion |
| VerfasserIn |
H. Kucharek, M. Scholder, A. P. Matthews |
| 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 ; 7, no. 3/4 ; Nr. 7, no. 3/4, S.167-172 |
| Datensatznummer |
250004253
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| Publikation (Nr.) |
 copernicus.org/npg-7-167-2000.pdf |
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| Zusammenfassung |
| In a system with at least one ignorable
spatial dimension charged particles moving in fluctuating fields are tied to the
magnetic field lines. Thus, in one-and two-dimensional simulations cross-field
diffusion is inhibited and important physics may be lost. We have investigated
cross-field diffusion in self-consistent 3-D magnetic turbulence by fully
3-dimensional hybrid simulation (macro-particle ions, massless electron fluid).
The turbulence is generated by the electromagnetic ion/ion beam instability. A
cold, low density, ion beam with a high velocity stream relative to the
background plasma excites the right-hand resonant instability. Such ion beams
may be important in the region of the Earth's foreshock. The field turbulence
scatters the beam ions parallel as well as perpendicular to the magnetic field.
We have determined the parallel and perpendicular diffusion coefficient for the
beam ions in the turbulent wave field. The result compares favourably well
(within a factor 2) with hard-sphere scattering theory for the cross-field
diffusion coefficient. The cross-field diffusion coefficient is larger than that
obtained in a static field with a Kolmogorov type spectrum and similar total fluctuation
power. This is attributed to the resonant behaviour of the particles in the
fluctuating field. |
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