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| Titel |
Radar observations of artificial E-region field-aligned irregularities |
| VerfasserIn |
E. Nossa, D. L. Hysell, C. T. Fallen, B. J. Watkins |
| 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 ; 27, no. 7 ; Nr. 27, no. 7 (2009-07-07), S.2699-2710 |
| Datensatznummer |
250016582
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| Publikation (Nr.) |
 copernicus.org/angeo-27-2699-2009.pdf |
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| Zusammenfassung |
| Artificial E region field aligned plasma density irregularities
(FAIs) were generated using HAARP in four different experimental modes
and observed with a coherent scatter radar imager located 450 km to
the southwest where it could detect field-aligned backscatter. The
experiments were conducted in July of 2008, during the Polar Aeronomy
and Radio Science Summer School (PARS), during quiet conditions in the
daytime when the E layer was dense and absorption was
modest. The echoes observed during zenith and magnetic zenith heating
experiments were deflected from their nominally anticipated horizontal
positions toward the midpoint position. The occurrence of hysteresis
when heating with amplitude modulated pulses implied the
development of the resonance instability, although the threshold for the
onset of instability appeared to be higher than what has been
predicted theoretically. Heating experiments involving pump
frequencies slightly above and below the second electron gyroharmonic
frequency produced no significant differences in the observed
echoes. Finally, heating with a pump frequency slightly above the
E region critical frequency appears to have produced FAIs at two
distinct altitudes where the upper-hybrid resonance condition could be
satisfied. |
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