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Wave acceleration of electrons in the Van Allen radiation belts

Horne, Richard B.; Thorne, Richard M.; Shprits, Yuri Y.; Meredith, Nigel P.; Glauert, Sarah A.; Smith, Andy J.; Kanekal, Shrikanth G.; Baker, Daniel N.; Engebretson, Mark J.; Posch, Jennifer L.; Spasojevic, Maria; Inan, Umran S.; Pickett, Jolene S.; Decreau, Pierrette M.E.. 2005 Wave acceleration of electrons in the Van Allen radiation belts. Nature, 437 (7056). 227-230. 10.1038/nature03939

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Abstract/Summary

The Van Allen radiation belts are two regions encircling the Earth in which energetic charged particles are trapped inside the Earth's magnetic field. Their properties vary according to solar activity and they represent a hazard to satellites and humans in space. An important challenge has been to explain how the charged particles within these belts are accelerated to very high energies of several million electron volts. Here we show, on the basis of the analysis of a rare event where the outer radiation belt was depleted and then re-formed closer to the Earth, that the long established theory of acceleration by radial diffusion is inadequate; the electrons are accelerated more effectively by electromagnetic waves at frequencies of a few kilohertz. Wave acceleration can increase the electron flux by more than three orders of magnitude over the observed timescale of one to two days, more than sufficient to explain the new radiation belt. Wave acceleration could also be important for Jupiter, Saturn and other astrophysical objects with magnetic fields.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1038/nature03939
Programmes: BAS Programmes > Global Science in the Antarctic Context (2005-2009) > Sun Earth Connections
ISSN: 0028-0836
NORA Subject Terms: Atmospheric Sciences
Space Sciences
Date made live: 21 Dec 2007 14:46
URI: http://nora.nerc.ac.uk/id/eprint/1813

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