Comprehensive Studies of Langmuir Turbulence Experiments at HAARP
Abstract
We report the results from a recent series of campaigns employing the HAARP HF transmitter 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, and aspect angle were recorded. Short pulse, low duty cycle experiments demonstrate control of artificial field-aligned irregularities (AFAI). Among the effects observed and studied are: SLT spectra including cascade, collapse, and co-existence spectra and an outshifted plasma line. High time resolution studies of the temporal evolution of the plasma line reveal the appearance of an overshoot effect on ponderomotive timescales. Plasma line spectra exhibit a marked dependence on aspect angle including the discovery of a second region of strong turbulence displaced southward from the primary HF interaction region along the geomagnetic field line. 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 2008
- Bibcode:
- 2008AGUFMSA42A..06S
- Keywords:
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- 2403 Active experiments