Abstract

The theoretical and experimental data on the study of the optical coefficients of electromagnetic waves in the super high frequency range 2–4,5 GHz and their relationship with the thickness of the conductive films by the example of aluminum are presented. It is showed that transformation of the relief of a thin-film structure with an increase in the bulk mass of the deposited material causes an increase in surface roughness with a maximum of 7 nanometers. It is worth noting that exactly for these thicknesses of the studied films the maximum absorption of the incident electromagnetic wave is experimentally achieved. Meanwhile, a theoretical calculation of the reflection, transmission and absorption coefficients showed the maximum absorption of the incident wave at a thickness of 5 nm. The difference between the experimental and theoretical values of the absorptivity is explained by the non-ideal geometry of ultrathin conductive surfaces. At the thicknesses from 1 nm to 10 nm the film itself is formed in the form of separate nanoislands.

Free electron laser based on multi-turn microtron-recuperator is currently operates at Novosibirsk. Whole facility is a coherent radiation source with ability of wavelength tuning in adequately wide range. The main parameters of radiation (wavelength and radiation power) are depends on electron beam parameters – its energy, average current, movement trajectory. The system of magnetic elements, in turn, appear to be a main instrument to control over beam movement trajectory. The structure, main parameters of this system, abilities of magnetic elements control system are described in this article.

The results of experimental investigations of the influence of distributed suction through a finely perforated surface on the spatial development of perturbations of the straight wing boundary layer at the nonlinear stage of its evolution are presented in this article. It was found that distributed suction reduces the intensity of integral pulsations for natural disturbances by 90 times. A spectral analysis of disturbances showed a decrease in the intensity of high-frequency fluctuations in a narrow frequency band by two orders of magnitude for natural and forced disturbances generated by an external acoustic field. It was found that the distributed suction affects the average flow, namely, when the suction is on, the turbulent state of the boundary layer is eliminated, its separation near the trailing edge of the wing and the laminar flow is defined in the boundary layer.

An experimental study of the effect of pulsations of free supersonic flow on the pulsations of the boundary layer of a flat plate with a sharp edge using a new three-channel hot-wire anemometer measurement system is carried out. The spatial-temporal distributions of the correlation coefficient are obtained for the boundary layer cross sections and for the laminar-turbulent transition region.

In a wind tunnel of low subsonic speeds, an experimental study was conducted of the windward flow of a trapezoidal model of a flying wing (UAV) with a locally installed perturbation generator in the region of maximum susceptibility on its surface. The generator was a three-dimensional roughness element whose height was comparable to the thickness of the boundary layer. The uniqueness of the work was that the experiments were carried out in a wind tunnel at real flight Reynolds numbers on a UAV model at a scale of 1:1. The results of visualization of the flow near a smooth surface and behind roughness were obtained using the method of liquid crystal thermography. The internal structure and processes of development of the longitudinal perturbation behind the roughness downstream were studied in detail using the thermoanemometry method.

This article is devoted to the search for conditions for optimal operation of a microhydroturbine model. The experiments were carried out in air medium. Velocity fields were measured in the outlet cone of a hydraulic turbine using an LDA system. It was shown that by modeling the flow in the air, using the integral swirl parameter S, it is possible to quickly determine the optimal regime of operation of the turbine for the given parameters of the water resource.

The article shows the selection of the optimal process regime for the growth of epitaxial layers of Si_1–xGe_x solid solutions from tin and gallium solution – melt on a Si<111> substrate, with the lowest dislocation densities that we experimentally achieved. An exponential relationship was found between the values of the dislocation density and the film thickness.With a smooth variable composition of the structure, respectively, by smoothly changing the lattiece parameters of the graded-gap solid solution, structurally perfect epitaxial layers Si_1–xGe_x (0 < x < 1) were obtained.

This work presents general studies of the influence of doping methods on the properties of elements with anomalous photovoltaic effects and the process of doping of semi-crystalline thin CdTe films with isovalent impurities is also investigated. The process of thermal diffusion has been studied.

A novel model of a metallic nanoparticle is proposed. The model represents the nanoparticle as a hollow sphere. The existence of a nanohollow inside a particle is related to the behavior of phonons. The strain in the walls of a particle when it's heated is calculated utilizing the theory of a thick-walled shell. We show that in the transition to the elastic state, the expansion strains at the surface of a nanoparticle become sufficient for melting. The dependency of melting temperature on the size of a nanoparticle is discussed.

The article briefly describes the stages of development of ideas about the atomic structure of matter from ancient philosophers to the present day. Various images of the periodic table of elements during its creation and in a modern form are also presented.