Cavitating Langmuir Turbulence Observed during High-Latitude Ionospheric Wave Interaction Experiments

Incoherent scatter radar data obtained during high power radio wave ionospheric interaction experiments performed in northern Scandinavia show an induced spectral line at the O-mode pump frequency simultaneous with strong enhancements at the natural Langmuir resonance frequency, both just below the reflection height. These characteristics provide an unmistakable signature of cavitating (a.k.a. strong) Langmuir turbulence, and show that this turbulence occurs not only in midlatitude but also during high latitude ionospheric interaction experiments. Cavitating turbulence is thus not dependent on specific geophysical conditions but is due to fundamental wave-plasma interaction processes in the ionospheric plasma.