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| Titel |
The expected imprint of flux rope geometry on suprathermal electrons in magnetic clouds |
| VerfasserIn |
M. J. Owens, N. U. Crooker, T. S. Horbury |
| 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 ; 27, no. 10 ; Nr. 27, no. 10 (2009-10-26), S.4057-4067 |
| Datensatznummer |
250016691
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| Publikation (Nr.) |
 copernicus.org/angeo-27-4057-2009.pdf |
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| Zusammenfassung |
| Magnetic clouds are a subset of interplanetary coronal mass ejections
characterized by a smooth rotation in the magnetic field direction, which is
interpreted as a signature of a magnetic flux rope. Suprathermal electron
observations indicate that one or both ends of a magnetic cloud typically
remain connected to the Sun as it moves out through the heliosphere. With
distance from the axis of the flux rope, out toward its edge, the magnetic
field winds more tightly about the axis and electrons must traverse longer
magnetic field lines to reach the same heliocentric distance. This increased
time of flight allows greater pitch-angle scattering to occur, meaning
suprathermal electron pitch-angle distributions should be systematically
broader at the edges of the flux rope than at the axis. We model this effect
with an analytical magnetic flux rope model and a numerical scheme for
suprathermal electron pitch-angle scattering and find that the signature of a
magnetic flux rope should be observable with the typical pitch-angle
resolution of suprathermal electron data provided ACE's SWEPAM instrument.
Evidence of this signature in the observations, however, is weak, possibly
because reconnection of magnetic fields within the flux rope acts to intermix
flux tubes. |
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