High Time-resolution Studies of RF Interaction Experiments at HAARP
Abstract
The high power HAARP HF transmitter is employed to generate and study strong Langmuir turbulence (SLT) in the interaction region of overdense ionospheric plasma. Diagnostics included the Modular UHF Ionospheric Radar (MUIR) sited at HAARP, the SuperDARN-Kodiak HF radar, and HF receivers to record stimulated electromagnetic emissions (SEE). Dependence of diagnostic signals on HAARP HF parameters, including pulselength, duty-cycle, aspect angle, and frequency were recorded. Short pulse, low duty cycle experiments demonstrate control of artificial field-aligned irregularities (AFAI) and isolation of ponderomotive effects. Among the effects observed and studied are: SLT spectra including cascade, collapse, and co-existence spectra and an outshifted plasma line under certain ionospheric conditions. High time resolution studies of the temporal evolution of the plasma line reveal the appearance of an overshoot effect on ponderomotive timescales. Bursty turbulence is observed in the collapse and cascade lines. Plasma line spectra exhibit a marked dependence on aspect angle with the strongest interaction region observed displaced southward of the HF zenith pointing angle. Experimental results are compared to previous high latitude experiments and predictions from recent modeling efforts.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFMSA33A1756S
- Keywords:
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- 2403 IONOSPHERE / Active experiments;
- 2471 IONOSPHERE / Plasma waves and instabilities;
- 6944 RADIO SCIENCE / Nonlinear phenomena;
- 7852 SPACE PLASMA PHYSICS / Solitons and solitary waves