Том 60, № 6 (2017)

We present the results of studying the ionospheric F₂ region airglow in the atomic-oxygen red line (λ = 6300Ǻ) when the ionosphere is pumped by high-power HF radio waves. Either thermal modulation of the background airglow brightness or, simultaneously with it, the red-line intensity enhancement were observed, depending on the ionospheric and plasma-wave parameters. Analysis of the red-line emission behavior makes it possible to separate the influence of the ohmic heating and acceleration of electrons by plasma turbulence on the airglow features.

We consider the behavior of the parameters of the ionospheric E_s layers according to the vertical sounding at the Sodankylä observatory and oblique sounding at the Lovozero (Murmansk region)—Gor’kovskaya station (Leningrad region) path during a superstorm of March 17, 2015. Temporal and spatial behavior of these parameters is compared. It was found that the storm significantly distorted the normal course of variations of the sporadic E_s layer characteristics. Specific behavior of the layers during a storm at points separated by about 300 km was detected. With the help of ray tracing calculations using the IRI model, oblique sounding ionograms were constructed for the radio path analyzed. Primary attention is given to the maximum usable frequency of the F₂ layer—MUF-F₂. Additionally, for the disturbed conditions where there is only a high-power E_s layer on the experimental ionograms, the values of MUF-E_s and the ratio K =MUF-E_s/f_oE_s for various cutoff frequencies f_oE_s of the E_s layer and its altitudes \( {h}_{E_s} \) are calculated within the framework of the well-known approximations. Calculations for the case of weak disturbance and semitransparent E_s layers are carried out with the IRI model adapted to the current diagnostics parameters. It was found that the calculated and experimental values of MUF-F₂ are close to each other or coincide, while this cannot be said about MUF-E_s. The calculated and experimental values of MUF-E_s can be matched in the model of mirror reflection from a flat layer for intense layers and the model of the E layer for thick E_s layers of low intensity.

We develop a mathematical model for the formation of underwater images of a perturbed sea surface. On the basis of this model, a method for determination of statistical spatio-temporal characteristics of wind waves, which uses the phenomenon of total internal light reflection at the water—air interface, is proposed.

We discuss the properties of the resonance reflectors applied in high-power relativistic backward-wave oscillators. The obtained results were used to develop a resonance reflector in the form of a section of a coaxial waveguide for a relativistic backward-wave oscillator operated in the ten-centimeter wavelength range. The results of preliminary experiments agree well with the calculations.

We study stability of a synchronous regime in hub clusters of the power networks, which are simulated by ensembles of phase oscillators. An approach allowing one to estimate the regions in the parameter space, which correspond to the global asymptotic stability of this regime, is presented. The method is illustrated by an example of a hub cluster consisting of one generator and two consumers.