Vol 58, No 10 (2016)

We present the experimental results concerning the features of large-scale artificial plasma-density irregularities excited in the ionospheric F₂ region by high-power HF radio waves. The experiments were performed in recent years using the SURA heating facility. It is shown that at the altitude of the pump-wave reflection, these irregularities are most efficiently generated in the magnetic zenith region. The effect of enhancement of the large-scale irregularity generation at the edge of the pump-wave beam is revealed. The results of studying large-scale irregularities recorded at the altitudes of the topside ionosphere are presented. Experimental results concerning the features of the internal gravity waves generated at the ionospheric altitudes during periodic heating of the ionospheric plasma by high-power HF radio waves are summarized and their possible influence on generation of artificial ionospheric irregularities at a long distance from the heater is discussed.

Within the framework of an approximate approach based on the representation of the Gardnerequation solitons as compound structures (different-polarity kinks), the non-quasistationary evolution of such solitary waves, which is stipulated by the variable quadratic-nonlinearity parameter α. The structure of the composite soliton is studied in cases that are critical for the quasistationary description where the predicted increase in the solitary-wave scales becomes unbounded on finite spatio-temporal intervals. The dependence of the spatial scales of the quasisoliton-field distribution on the quadratic-nonlinearity coefficient near the critical point for the power-law time dependence α(t) is studied in detail. The obtained solution is compared with the results of direct numerical simulation of the Gardner equation with variable coefficients.

We discuss possible applications of relativistic pulsed microwave electronic devices in physics and engineering of modern free-electron lasers. In particular, the possibilities of using high-power millimeter-wave radiation pulses for electron pitching in the operating space of the laser (in a microwave undulator), as well as for cooling and focusing of electron bunches, are considered.

We present experimental results on a high-power transmission line from the broadband pulsed Ka-band gyro-TWT to the phased antenna array. The transmission line is designed to operate in a pulse-periodic regime with a pulse width of up to 250 μs, a duty factor of 8, and an average output power of up to 15 kW. Amplitude–frequency and phase–frequency characteristics of the transmission line were measured at a low power level. It is shown that the nonlinearity of the phase–frequency characteristic does not exceed ±10° in the 34 ± 0.5 GHz frequency band.

We describe an approach for analyzing the generalized synchronization of the unidirectionally coupled virtual cathode oscillators on the within the framework of the large-particle method. The generalized synchronization is diagnosed by the auxiliary-system method to confirm the results of the study.

We calculate the characteristics (the extinction and loss coefficients) of a fiber-optic polarizer with a metal film and a dielectric buffer layer. It is shown that using the metals, in which the real part of the complex refractive index is much smaller than unity (e.g., silver, gold, and copper), in such polarizers makes it possible to significantly reduce the loss for the fundamental transmitted TE₀ mode compared with the aluminum-film polarizers. In this case, a sufficiently high extinction coefficient is preserved.