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Ionospheric plasma response to HF waves operating at frequencies close to the third harmonic of the electron gyrofrequency

Honary, Farideh and Stocker, A. J. and Robinson, T. R. and Stubbe, P. (1995) Ionospheric plasma response to HF waves operating at frequencies close to the third harmonic of the electron gyrofrequency. Journal of Geophysical Research - Space Physics, 100 (A11). pp. 21489-21501. ISSN 0148-0227

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    Abstract

    Experimental results concerning European incoherent scatter observations of heater-induced electron temperature enhancements, anomalous absorption of low-power HF probe waves, and the spectrum of stimulated electromagnetic emission (SEE) in the sidebands of a high-power HF electromagnetic wave are presented. For the experiments reported in this paper, an O mode pump wave was transmitted vertically into the F region above Tromsø, Norway, while the injected frequency was varied in small steps around the third harmonic of the electron gyrofrequency. Systematic variations with pump frequency were observed in the data obtained from all three diagnostics. Measurements of anomalous absorption, the downshifted maximum (DM) spectral feature, and heater-induced electron temperature enhancements all exhibited broad minima as the heater frequency approached the third harmonic of the electron gyrofrequency. In addition, the signal strength of the HF probe wave measured during heater off periods is also reduced at these and higher heater frequencies. The experimental findings suggest that at heater frequencies in the vicinity of the third gyroharmonic, small-scale field-aligned irregularities are not excited, whereas very small scale irregularities, of the order of a few electron cyclotron radii, which are responsible for the production of fast electrons, may be generated. The observed reduction in the diagnostic signal strength is then attributed to the ionized patches produced by these energetic electrons.

    Item Type: Article
    Journal or Publication Title: Journal of Geophysical Research - Space Physics
    Additional Information: Copyright (1995) American Geophysical Union.
    Uncontrolled Keywords: Ionosphere ; Auroral ionosphere ; Electric fields ; heating DCS-publications-id ; art-85 ; DCS-publications-credits ; iono-fa ; DCS-publications-personnel-id ; 5
    Subjects: UNSPECIFIED
    Departments: Faculty of Science and Technology > Engineering
    Faculty of Science and Technology > Physics
    ID Code: 9985
    Deposited By: Dr Steve Marple
    Deposited On: 24 Jun 2008 17:53
    Refereed?: Yes
    Published?: Published
    Last Modified: 26 Jul 2012 18:42
    Identification Number:
    URI: http://eprints.lancs.ac.uk/id/eprint/9985

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