Journal article
An impenetrable barrier to ultrarelativistic electrons in the Van Allen radiation belts
Nature (London), Vol.515(7528), pp.531-534
11/27/2014
DOI: 10.1038/nature13956
PMID: 25428500
Abstract
Early observations indicated that the Earth's Van Allen radiation belts could be separated into an inner zone dominated by high-energy protons and an outer zone dominated by high-energy electrons. Subsequent studies showed that electrons of moderate energy (less than about one megaelectronvolt) often populate both zones, with a deep 'slot' region largely devoid of particles between them. There is a region of dense cold plasma around the Earth known as the plasmasphere, the outer boundary of which is called the plasmapause. The two-belt radiation structure was explained as arising from strong electron interactions with plasmaspheric hiss just inside the plasmapause boundary, with the inner edge of the outer radiation zone corresponding to the minimum plasmapause location. Recent observations have revealed unexpected radiation belt morphology, especially at ultrarelativistic kinetic energies (more than five megaelectronvolts). Here we analyse an extended data set that reveals an exceedingly sharp inner boundary for the ultrarelativistic electrons. Additional, concurrently measured data reveal that this barrier to inward electron radial transport does not arise because of a physical boundary within the Earth's intrinsic magnetic field, and that inward radial diffusion is unlikely to be inhibited by scattering by electromagnetic transmitter wave fields. Rather, we suggest that exceptionally slow natural inward radial diffusion combined with weak, but persistent, wave-particle pitch angle scattering deep inside the Earth's plasmasphere can combine to create an almost impenetrable barrier through which the most energetic Van Allen belt electrons cannot migrate.
Details
- Title: Subtitle
- An impenetrable barrier to ultrarelativistic electrons in the Van Allen radiation belts
- Creators
- D N Baker - University of Colorado BoulderA N Jaynes - University of Colorado BoulderV C Hoxie - University of Colorado BoulderR M Thorne - University of California, Los AngelesJ C Foster - Massachusetts Institute of TechnologyX Li - University of Colorado BoulderJ F Fennell - Space Sciences LaboratoryJ R Wygant - University of MinnesotaS G Kanekal - Goddard Space Flight CenterP J Erickson - Massachusetts Institute of TechnologyW Kurth - University of IowaW Li - University of California, Los AngelesQ Ma - University of California, Los AngelesQ Schiller - University of Colorado BoulderL Blum - University of Colorado BoulderD M Malaspina - University of Colorado BoulderA Gerrard - New Jersey Institute of TechnologyL J Lanzerotti - New Jersey Institute of Technology
- Resource Type
- Journal article
- Publication Details
- Nature (London), Vol.515(7528), pp.531-534
- DOI
- 10.1038/nature13956
- PMID
- 25428500
- ISSN
- 0028-0836
- eISSN
- 1476-4687
- Language
- English
- Date published
- 11/27/2014
- Academic Unit
- Physics and Astronomy; University College Courses
- Record Identifier
- 9984199757702771
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