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Titel |
Letter to the Editor: First direct observations of the reduced striations at pump frequencies close to the electron gyroharmonics |
VerfasserIn |
F. Honary, T. R. Robinson, D. M. Wright, A. J. Stocker, M. T. Rietveld, I. McCrea |
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 ; 17, no. 9 ; Nr. 17, no. 9, S.1235-1238 |
Datensatznummer |
250013816
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Publikation (Nr.) |
copernicus.org/angeo-17-1235-1999.pdf |
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Zusammenfassung |
It is well known that the ionospheric plasma
response to high-power HF radio waves changes drastically as the heater
frequency approaches harmonics of the electron gyrofrequency. These include
changes in the spectrum of the stimulated electromagnetic emission, reduction in
the anomalous absorption of low-power diagnostic waves propagating through the
heated volume, and reduction in the large scale F-region heating. Theoretical
models as well as previous experimental evidence point towards the absence of
small-scale field-aligned plasma density irregularities at pump frequencies
close to electron gyroharmonics as the main cause of these changes. Results
presented in this paper are the first direct observations of the reduced
striations at the 3rd gyroharmonic made by the CUTLASS radar. In addition,
simultaneous EISCAT observations have revealed that the "enhanced
ion-line" usually present in the EISCAT ion-line spectrum during the first
few seconds after heater switch on, persisted at varying strengths while the
heater was transmitting at frequencies close to the 3rd electron gyroharmonics.
Key words. Ionosphere (active experiments; ionospheric
irregularities) · Radio science (ionospheric physics) |
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