Spatial Structure of Plasma Density Perturbations Excited at Altitudes of the Upper and Outer Ionosphere During <i>F</i>2-Layer Heating by Powerful HF Radio Waves

The results of measurements of the spatial structure of variations in the electron concentration excited at altitudes of the Earth’s upper and outer ionosphere by modification of the F2-layer of the mid-latitude ionosphere by powerful HF radio waves of O-polarization radiated by the SURA heating facility are analyzed. The results were obtained by the method of low-orbit satellite radio tomography. The characteristics of a cavity with a reduced plasma concentration formed at altitudes near the height of reflection of a powerful radio wave, ducts with an increased plasma concentration formed at altitudes of the external ionosphere due to the displacement of plasma from the region of its strong heating along the geomagnetic field, and various wave disturbances HF-induced at ionospheric altitudes are considered. In addition, the properties of detected plasma density disturbances of a special nature, revealed in a vertical column above the SURA facility, were also studied. The sizes of studied irregularities are from several tens to several hundred kilometers, and the area of their registration extends far beyond the region of resonant interaction of a powerful O-polarized radio wave with the ionospheric plasma near the height of its reflection, where the most intense artificial ionospheric turbulence is excited.