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| Titel |
Compressible coherent structures at ion scales in the slow solar wind |
| VerfasserIn |
Denise Perrone, Olga Alexandrova, André Mangeney, Milan Maksimovic, Catherine Lacombe |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250136349
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| Publikation (Nr.) |
 EGU/EGU2016-17373.pdf |
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| Zusammenfassung |
| We present a study of magnetic field fluctuations close to the ion scales in a slow solar wind
stream. The nature of these fluctuations is found to be characterized by coherent
structures. Although previous studies have shown that coherent current sheets can be
considered as the principal cause of intermittency at the solar wind ion scales, here we
show for the first time that, in the case of the slow solar wind, a large variety of
coherent structures participates to intermittency at proton scales, and current sheets are
not the most common ones. Precisely, we find here compressible (δB∥ ≫ δB⊥),
linearly polarized structures in form of magnetic holes, solitons and shock waves.
Examples of Alfvénic structures (δB⊥ > δB∥) are identified as current sheets and
vortex-like structures. Some of these vortices have δB⊥≫ δB∥, but the majority of
them are characterized by δB⊥ ≳ δB∥. Thanks to multi-point measurements by
Cluster spacecraft, we could determine the normal of the coherent structures and their
propagation velocity and spatial scale along this normal. Independently of the nature
of the structures, the normal is always perpendicular to the local magnetic field,
meaning that k⊥ ≫ k∥. The spatial scales of the studied structures are found to
be 2 to 5 times the proton gyroradius or proton inertial length. Most of them are
simply convected by the wind, but 25% propagate in the plasma frame. Possible
interpretations of the observed structures and the connection with the plasma heating are
discussed. |
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