Vestnik NSU. Series: Physics. 2014. V9, i 4

Quantum Optics, Quantum Electronics

G. M. Borisov, V. G. Gol’dort, A. A. Kovalyov, S. A. Kochubei, D. V. Ledovskokh V. V. Preobrazhenskii, M. A. Putyato, N. N. Rubtsova, B. R. Semyagin
SPECIFIC FEATURES OF SECOND HARMONIC GENERATION OF FEMTOSECOND YB3+:KY(WO4)2 LASER RADIATION IN HETEROSTRUCTURES A3B5 WITH ASYMMETRIC QUANTUM WELLS

Second harmonic generation of femtosecond Yb3+:KY(WO4)2 laser radiation was investigated in semiconductor heterostructure grown at the singular GaAs substrate of orientation (001) and including a set of asymmetric quantum
wells. Azimuth second harmonic dependence was investigated in transmission for the incidence angles of 10–70 degree, and in reflection for incidence angle of 45 degree by application of p- and s-polarized pumping radiation. Second harmonic signals from heterostructure were several times higher than those from the substrate at p-polarized pumping in transmission and for the cases of p- and s-polarized pumping in reflection. The case of s-polarized pumping radiation and p-polarized second harmonic radiation in reflection resulted in high isotropic contribution from the heterostructure to second harmonic; here, the azimuth dependencies from the heterostructure and from the substrate are essentially different.

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Radiophysics and Electronics

S. A. Kuznetsov, M. A. Astafev, P. A. Lazorsky, V. F. Sklyarov E. A. Lonshakov, A. V. Arzhannikov
SPECTRAL MEASUREMENTS OF DIELECTRIC PROPERTIES OF POLYPROPYLENE FILMS IN THE SUBTERAHERTZ FREQUENCY RANGE

We describe three alternative quasi-optical methods for measuring dielectric properties of low-absorbing polymeric films at subterahertz frequencies using BWO-spectroscopy. For two of them, the dielectric permittivity of a pure film is
determined through amplitude-phase measurements when the film is inserted into Mach-Zehnder and Fabry-Perot interferometers. In the third case, the permittivity is retrieved via investigating spectral features of a supplementary resonant metallic structure created on the film’s surface to enhance its dispersive properties. The described methods were applied to measure the dielectric permittivity for polypropylene films of different thickness (from 10 to 512 um) from the GoodFellow company (UK). The experimental data obtained by these three techniques are compared with each other and the analysis of factors explaining discrepancy in the measured values of the dielectric permittivity is presented.

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Physics of Field, Neutral and Ionized Gases

V. V. Kozlov, G. R. Grek, Yu. A. Litvinenko, S. N. Tolkachev, V. G. Chernoray
EXPERIMENTAL STUDIES OF THE LOCALIZED DISTURBANCES AND THEIR SECONDARY HIGH-FREQUENCY INSTABILITY IN THE FLAT PLATE, UNSWEPT AND SWEPT WING BOUNDARY LAYER (REVIEW)

Results of experimental studies of the streaky structures instability at nonlinear stage of this process in the shear flows are shown in this work. Flow patterns of the streaky structures with secondary high-frequency disturbances generated on them during its spatial evolution are discussed. Different scenarios of the coherent vortical structures occurrence and downstream evolution in the flat plate, unswept and swept wing boundary layer are considered. Features of the sinusoidal and varicose instability of the longitudinal stationary streaky structure at nonlinear stage of its downstream development are shown. To these features concern: modulation of streaky structure in transverse and streamwise direction by frequency of secondary disturbances, occurrence of new streaky structures downstream and occurrence and development of the nonstationary localized vortices such as ?-structures in both cases. Development of a nonlinear stage of flow instability is considered both in the region of the adverse and zero pressure gradient

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S. N. Tolkachev, V. S. Kaprilevskaya, V. V. Kozlov
THE ROLE OF TWO-DIMENSIONAL ROUGHNESS ELEMENT IN THE LAMINAR-TURBULENT PROCESS IN THE FAVORABLE PRESSURE GRADIENT OF THE SWEPT WING

In the article using a liquid crystal thermography investigated the development of stationary and secondary disturbances, which were excited by cylindrical and two-dimensional roughness elements. It was shown, that two-dimensional
roughness element has a destabilizing effect on disturbances, induced by cylindrical roughness element. Also the twodimensional roughness element is able to excite the stationary structures, and then the secondary disturbances the frequency interval of which is lower than in the case of stationary vortices excitation by cylindrical roughness element.

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A. V. Fedorov, A. V. Shulgin, D. A. Tropin
CALCULATION OF PHYSICAL AND CHEMICAL TRANSFORMATIONS IN METHANE – IRON PARTICLES MIXTURE

The refined model of ignition methane – air and reactive iron particle mixture that takes into account the kinetics of particles oxide film growth is developed. Comparison of the ignition delay times in methane-air-particles mixture obtained in the calculation of the proposed model with experimental data showed their satisfactory agreement in the range of temperatures 900–1200 K and pressures 1–1.2 MPa. At low exposure temperatures the new model describes the ignition delay time more accurately than our model constructed earlier.

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Solid-State and Semiconductor Physics, Physics of Nanostructures

A. P. Zavjalov, K. V. Zobov, V. V. Syzrantsev, S. P. Bardakhanov
CONCEPT OF FULL SURFACE AT SYNTESIS AND APPLICATION OF SILICA NANOPOWDER

The paper describes a model of synthesis and analysis of the application of nano-silica obtained by electron beam evaporation. The authors developed the approach that shows of the specific and fully surfaces of nanopowders to have
more significance then the size of the nanoparticles. The experimental results and theoretical models supporting this concept are presented. In particular, the connection between the strength of the epoxy and the total surface value dispersed into epoxy is shown. In the synthesis of large quantities of nanopowder we can use the model concepts to predict specific surface directly from the averaged parameters of synthesis. The main factor for a used synthesis scheme is presented: the multiplication a product of mass performance on specific surface area. The combination of this factor with the model representations of specific surface evaluation allows to estimate the quality and efficiency of the synthesis process. The nanopowder total surface versatility as a criterion of comparability of different modes, and possibly synthesis processes is shown.

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M. A. Parashchenko, N. S. Filippov, V. V. Kirienko, S. I. Romanov ELECTROKINETIC LIQUID FLOW SENSOR

This paper deals with fabrication and characterization of liquid flow sensor based on electrokinetic effect – streaming potential. The possibility of using silicon microchannel membrane as a sensing element of the sensor has been demonstrated. Electric response of the sensor has been determined by passing deionized water through the membrane. A linear dependence of the operating characteristic has been found. Sensitivity and performance of the electrokinetic device have been evaluated. The optimal design of the liquid flow sensor has been proposed.

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