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Studies Of Self-Focusing Instability At Arecibo, D. T. Farley, C. Lahoz, Bela G. Fejer

Bela G. Fejer

Precisely simultaneous radar and satellite measurements at the altitude of reflection of a strong HF heating wave above the Arecibo Observatory were made on June 7, 1977. Parametric instabilities produce strong enhancements in the plasma line and ion line incoherent scatter radar echoes. These echoes also exhibit periodic deep fading that is attributed to a self-focusing instability. This explanation was confirmed by the in situ observation of electron density fluctuations with peak-to-peak amplitudes reaching at least 3% and a spatial dependence that corresponded closely to the radar fading pattern, at least for irregularity wavelengths ranging from a few hundred meters …