Cavitating Langmuir turbulence observed during high-latitude ionospheric wave interaction experiments

Incoherent scatter radar data obtained during high power radio wave ionosph eric interaction experiments performed in northern Scandinavia show an indu ced spectral line at the O-mode pump frequency simultaneous with strong enh ancements 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 turbu lence occurs not only in midlatitude but also during high latitude ionosphe ric interaction experiments. Cavitating turbulence is thus not dependent on specific geophysical conditions but is due to fundamental wave-plasma inte raction processes in the ionospheric plasma.