Evolution of the frequency spectrum of an extraordinary wave near the upper hybrid resonance in a turbulent plasma

One investigated into frequency spectrum of an extraordinary wave shaped under wave multiple scattering near the upper hybrid resonance and behind transformation point. One applied both the eikonal approach and approach in terms of high length of wave of fluctuations causing small angle scattering. One demonstrated coincidence of those approaches. It is shown that near the upper hybrid resonance the spectral spreading of a sounding wave is proportional to its wave vector. It, as well as, the predicted value of spreading makes small angle scattering one of the main effects to explain vast spreading of spectra observed during the experiment