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    The Intensities of High Frequency‐Enhanced Plasma and Ion Lines During Ionospheric Heating (2019)
    Wiley
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    Publication Date: 2019
    Description: Abstract An ultrahigh frequency (UHF) observation during an ionospheric heating campaign at European Incoherent SCATter scientific association (EISCAT) demonstrates that the electron temperature and the intensities of the enhanced plasma and ion lines systematically vary as a function of the pump frequency near the fifth electron gyroharmonic. Specifically, with the change in the pump frequency, the weaker the enhancement in the electron temperature is, the more intense the intensities of the enhanced ion line is. The analysis shows that the enhanced electron temperature plays a significant role in determining the intensities of the enhanced Langmuir and ion acoustic waves by the parametric decay instability and the oscillation two‐stream instability, and the intensities of the enhanced plasma and ion lines depend on whether the enhanced Langmuir and ion acoustic waves satisfy the Bragg condition exactly or approximately. Moreover, an alternative explanation for the overshoots in the enhanced plasma and ion lines is presented, namely, the overshoots may be attributed not only to the anomalous absorption of the pump but also to the modifications of the plasma on the traveling path of the enhanced Langmuir and ion acoustic waves.
    Print ISSN: 2169-9380
    Electronic ISSN: 2169-9402
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 2
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    The behavior of electron density and temperature during ionospheric heating near the fifth electron gyrofrequency (2016)
    Wiley
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    Publication Date: 2016-12-31
    Description: The experimental phenomena involving the changes in electron temperature and electron density as a function of pump frequency during an ionospheric heating campaign at EISCAT near Tromsø, Norway, are reported. When the pump frequency is slightly above the fifth electron gyrofrequency, the UHF radar observation shows some apparent enhancements over a wide altitude range in radar echo, ion line and electron density respectively, which are apparently altitude independent and consistent temporally with the up-shifting and spread of plasma line around the reflection altitude. However, they do not in fact correspond to true increase in electron density. Based on some existing theories, some discussions are presented to try to explain the above enhancements and the up-shifting and spread of plasma line. Even so, the mechanism remains to be determined. In addition, the observation also shows some enhancements in electron temperature as a function of pump frequency around the reflection altitude of the pump, which are depend on the behavior of dispersion of the upper hybrid wave near the fifth electron gyrofrequency.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 3
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    The extending of observing altitudes of plasma and ion lines during ionospheric heating (2018)
    Wiley
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    Publication Date: 2018-01-17
    Description: The ultra-high frequency (UHF) observation during an ionospheric heating experiment on 11 March 2014 at the European Incoherent Scatter Scientific Association (EISCAT) Tromsø site illustrated a remarkable extension of observing altitudes of the enhanced plasma line and the ion line, implying that the enhanced ion acoustic wave and Langmuir wave should satisfy the Bragg condition within the extending altitude range. An analysis shows that the dependence of the wave number of the traveling ion acoustic wave on the profiles of enhanced electron temperature and ion mass, as are expected from the dispersion relation of the ion acoustic wave, leads to the extension of observing altitudes of the enhanced ion line. In addition, the altitude extension of the enhanced plasma line is dependent mainly on the profile of the electron density, although it is not independent of the profile of the electron temperature. Considering a small gradient profile of electron density, however, the enhanced electron temperature, as well as the thermal conduction along the magnetic field, may lead to the altitude extension of the enhanced plasma line.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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