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| Titel |
Energetic particle parallel diffusion in a cascading wave turbulence in the foreshock region |
| VerfasserIn |
F. Otsuka, Y. Omura, O. Verkhoglyadova |
| 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 ; 14, no. 5 ; Nr. 14, no. 5 (2007-09-07), S.587-601 |
| Datensatznummer |
250012275
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| Publikation (Nr.) |
 copernicus.org/npg-14-587-2007.pdf |
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| Zusammenfassung |
| We study parallel (field-aligned) diffusion of energetic particles in the
upstream of the bow shock with test particle simulations. We assume parallel
shock geometry of the bow shock, and that MHD wave turbulence convected by
the solar wind toward the shock is purely transverse in one-dimensional
system with a constant background magnetic field. We use three turbulence
models: a homogeneous turbulence, a regular cascade from a large scale to
smaller scales, and an inverse cascade from a small scale to larger scales.
For the homogeneous model the particle motions along the average field are
Brownian motions due to random and isotropic scattering across 90 degree
pitch angle. On the other hand, for the two cascade models particle motion is
non-Brownian due to coherent and anisotropic pitch angle scattering for
finite time scale. The mean free path λ|| calculated by the
ensemble average of these particle motions exhibits dependence on the
distance from the shock. It also depends on the parameters such as the
thermal velocity of the particles, solar wind flow velocity, and a wave
turbulence model. For the inverse cascade model, the dependence of
λ|| at the shock on the thermal energy is consistent with the
hybrid simulation done by Giacalone (2004), but the spatial dependence
of λ|| is inconsistent with it. |
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