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| Titel |
Apparent temperature anisotropies due to wave activity in the solar wind |
| VerfasserIn |
D. Verscharen, E. Marsch |
| 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 ; 29, no. 5 ; Nr. 29, no. 5 (2011-05-25), S.909-917 |
| Datensatznummer |
250017025
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| Publikation (Nr.) |
 copernicus.org/angeo-29-909-2011.pdf |
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| Zusammenfassung |
| The fast solar wind is a collisionless plasma permeated by
plasma waves on many different scales. A plasma wave represents the natural
interplay between the periodic changes of the electromagnetic field and the
associated coherent motions of the plasma particles. In this paper, a model
velocity distribution function is derived for a plasma in a single, coherent, large-amplitude wave. This model allows one to study the kinetic
effects of wave motions on particle distributions. They are by in-situ
spacecraft measured by counting, over a certain sampling time, the particles
coming from various directions and having different energies. We compare our
results with the measurements by the Helios spacecraft, and thus find that by
assuming high wave activity we are able to explain key observed features of
the measured distributions within the framework of our model. We also address
the recent discussions on nonresonant wave–particle interactions and apparent
heating. The applied time-averaging procedure leads to an apparent ion
temperature anisotropy which is connected but not identical to the intrinsic
temperature of the underlying distribution function. |
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