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Persistent URL http://purl.org/net/epubs/work/11164289
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Record Id 11164289
Title Ion Acceleration by Alfven Waves on Auroral Field Lines
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Abstract Observations of ion acceleration along auroral field lines at the boundary of the plasma sheet and tail lobe show that the energy of the ions increases with decreasing density. The observations can be explained by ion acceleration through Landau resonance with kinetic Alfven waves (KAWs) such that kA ยท vi = !A, where kA is the wave vector, vi is the ion resonance velocity and !A is the Alfven wave frequency. The ion resonance velocities are proportional to the Alfven velocity which increases with decreasing density. This is in agreement with the data if the process is occurring at the plasma sheet tail lobe boundary. A quasi-linear theory of ion acceleration by KAWs is presented. These ions propagate both down towards the earth and away from the earth. The positions of the Freja and Polar satellites indicate that the acceleration takes place between the two satellites, between 1Re and 5Re. The downward propagating ions develop a horseshoe-type of distribution which has a positive slope in the perpendicular direction. This type of distribution can produce intense lower hybrid wave activity, which is also observed. Finally, the filamentation of shear Alfven waves is considered. It may be responsible for large-scale density striations.
Organisation CLF , STFC
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Related Research Object(s): 64838
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Language English (EN)
Type Details URI(s) Local file(s) Year
Preprint Phys Scripta 2013. ion_acc.pdf 2013