Excitation of electron cyclotron harmonic waves in the inner Saturn magnetosphere within local plasma injections: EXCITATION OF ECH WAVES AT SATURN

X. Tao; R. M. Thorne; R. B. Horne; S. Grimald; C. S. Arridge; G. B. Hospodarsky; D. A. Gurnett; A. J. Coates; F. J. Crary

doi:10.1029/2010JA015598

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Excitation of electron cyclotron harmonic waves in the inner Saturn magnetosphere within local plasma injections: EXCITATION OF ECH WAVES AT SATURN

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Excitation of electron cyclotron harmonic waves in the inner Saturn magnetosphere within local plasma injections: EXCITATION OF ECH WAVES AT SATURN

X. Tao, R. M. Thorne, R. B. Horne, S. Grimald, C. S. Arridge, G. B. Hospodarsky, D. A. Gurnett, A. J. Coates and F. J. Crary

Journal of Geophysical Research: Space Physics, Vol.115(A12), A12204

12/2010

DOI: 10.1029/2010JA015598

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Abstract

[1] Strong electron cyclotron harmonic (ECH) waves have been observed by Cassini associated with local plasma injection regions in the Saturnian magnetosphere. Using measured electron distributions from the Cassini plasma spectrometer, we calculated local growth rates and path-integrated wave gain of ECH waves inside an injection event using the HOTRAY code. We showed that electrons with energy near a few eV have a collision frequency comparable to their bounce frequency; thus, they cannot have an empty loss cone. We then demonstrated that the growth of ECH waves inside the injection event can be driven by electron phase space density gradients associated with the loss cone distribution of injected electrons at energies between a few hundred eV and a few keV. This conclusion is contrary to previous results that the source of free energy for growth of ECH waves is provided by electrons near a few eV. Results in this work are helpful for understanding the generation of ECH waves and their roles in electron dynamics in the Saturnian magnetosphere.

Details

Title: Subtitle: Excitation of electron cyclotron harmonic waves in the inner Saturn magnetosphere within local plasma injections: EXCITATION OF ECH WAVES AT SATURN
Creators: X. Tao - University of California, Los Angeles
R. M. Thorne - University of California, Los Angeles
R. B. Horne - British Antarctic Survey
S. Grimald - Université Toulouse III - Paul Sabatier
C. S. Arridge - University College London
G. B. Hospodarsky - University of Iowa
D. A. Gurnett - University of Iowa
A. J. Coates - University College London
F. J. Crary - Southwest Research Institute
Resource Type: Journal article
Publication Details: Journal of Geophysical Research: Space Physics, Vol.115(A12), A12204
DOI: 10.1029/2010JA015598
ISSN: 0148-0227
eISSN: 2156-2202
Language: English
Date published: 12/2010
Academic Unit: Physics and Astronomy
Record Identifier: 9984455276002771

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