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| Titel |
Modelling of optical emissions enhanced by the HF pumping of the ionospheric F-region |
| VerfasserIn |
T. Sergienko, B. Gustavsson, U. Brandstrom, K. Axelsson |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 30, no. 5 ; Nr. 30, no. 5 (2012-05-31), S.885-895 |
| Datensatznummer |
250017229
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| Publikation (Nr.) |
 copernicus.org/angeo-30-885-2012.pdf |
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| Zusammenfassung |
| Strong enhancement of the optical emissions with excitation threshold from
1.96 eV (630.0 nm from O(1D)) up to 18.75 eV (427.8 nm from N2+(1NG))
have been observed during experiments of the ionosphere modification by high
power HF radio waves. Analysis of the optical emission ratios showed clearly
that a significant part of the ionospheric electrons have to be accelerated
to energies above 30 eV and more in the region where the HF radio wave
effectively interacts with the ionospheric plasma. The Monte-Carlo model of
electron transport and the optical emission model were used to study the
dependence of the optical emission intensity on the acceleration electron
parameters. We obtained the following results from analysis of the enhanced
intensities of the four optical emissions (630.0, 557.7, 844.6 and 427.8 nm)
observed in the EISCAT heating experiment on 10 March 2002. The 630.0
emission with an excitation threshold of 1.96 eV is formed predominately by
the thermal electrons, where the accelerated electrons play a minor role in the
excitation of this emission. In order to explain the experimentally observed
intensity ratios, the accelerated electrons must gain energies of more than
60 eV. For accelerated electrons with a power law energy dependence, the
efficiency of the optical emission excitation depends on the exponent
defining the shape of the electron spectra. However, an agreement with the
observed emission intensities is achieved for exponent values not less than
zero. Moreover, increasing the exponent to higher values does not affect the
emission intensity ratios. |
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