Gyroharmonic properties of the middle-scale artificial ionospheric turbulence during heating of the ionospheric F2 layer by a high-power O-mode radio wave

We present the results of studying the properties of artificial F-spread that appears on ionograms during heating of the ionospheric F2 region by a high-power O-mode radio wave. It is shown that the regions of resonant interaction of a high-power radio wave with plasma, where the pump-wave energy is almost totally absorbed and the plasma is subject to intense heating, affect significantly the development of a self-focusing instability of a high-power radio wave and the generation of middle-scale (with characteristic scales across the magnetic field l⊥ ≈ 0.4–1.5 km) artifical ionospheric inhomogeneities. It is established that the intensity of such inhomogeneities depends on the sign and magnitude of detuning of the pump-wave frequency with respect to the electron gyroresonance harmonic frequency Δf = fPW − nfce and has the minimum value for Δf ≈ −20 kHz, thus demonstrating the asymmetry of the gyroharmonic properties of their excitation mechanism. Relationship between the observed phenomena and known characteristics of the artificial ionospheric turbulence for fPW ≈ nfce is analyzed.