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Trapping and acceleration of upflowing ionospheric electrons in the magnetosphere by electrostatic electron cyclotron harmonic (ECH) waves

Horne, Richard B.. 2015 Trapping and acceleration of upflowing ionospheric electrons in the magnetosphere by electrostatic electron cyclotron harmonic (ECH) waves. Geophysical Research Letters, 42 (4). 975-980. https://doi.org/10.1002/2014GL062406

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Abstract/Summary

During geomagnetically active conditions upflowing field-aligned electrons which form part of the Birkland current system have been observed at energies of up to 100 eV. If the first adiabatic invariant is conserved these electrons would reach the conjugate ionosphere without trapping in the magnetosphere. Here we show, by using quasi-linear diffusion theory, that electrostatic electron cyclotron harmonic (ECH) waves can diffuse these low energy electrons in pitch angle via Doppler shifted cyclotronresonance and trap them in the magnetosphere. We show that energy diffusion is comparable to pitch angle diffusion up to energies of a few keV. We suggest that ECH waves trap ionospheric electrons in the magnetosphere and accelerate them to produce butterfly pitch-angle distributions at energies of up to a few keV. We suggest that ECH waves play a role in magnetosphere-ionosphere coupling and help provide the source electron population for the radiation belts.

Item Type: Publication - Article
Digital Object Identifier (DOI): https://doi.org/10.1002/2014GL062406
Programmes: BAS Programmes > BAS Programmes 2015 > Space Weather and Atmosphere
ISSN: 0094-8276
Additional Keywords: trapping, acceleration, ECH waves
Date made live: 07 Nov 2014 17:10 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/508762

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