SIBERIAN JOURNAL OF PHYSICS. Scientific Journal. 2019. V14, i 4

High-Energy and Accelerator Physics, Physics of High-Temperature Plasma

Glinskiy V. V., Timofeev I. V., Annenkov V. V., Arzhannikov A. V. Computer Simulations of Electromagnetic Emissions Produced via Injection of Electron Beam into a Plasma with Strong Transverse Density Gradients Siberian Journal of Physics, 2019, vol. 14, no. 4, p. 5–16. (in Russ.) DOI 10.25205/2541-9447-2019-14-4-5-16

Recent experiments on the injection of kiloampere electron beams into a magnetized plasma at the GOL-PET facility have shown that the power of sub-terahertz radiation escaping from the plasma along the magnetic field increases by more than an order of magnitude if strong transverse density gradients are preliminarily created in the plasma. In this paper, the influence of transverse in homogeneities of plasma density on the efficiency of electromagnetic radiation generation near the harmonics of the plasma frequency is studied using particle-in-cell simulations. Simulations performed for the real relative density of the beam and the real spatial scales of the in homogeneity show that the beam instability develops only in the density wells, and the small transverse size of its localization comparable with the wavelength contributes to a more efficient conversion of unstable oscillations into electromagnetic ones. Despite the fact that radiation at the plasma frequency is blocked across the leading magnetic field, it can leave the generation region with the decrease of the plasma density in the longitudinal direction.

Keywords
electromagnetic radiation, beam-plasma interaction, linear mode conversion

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Trufanov D. Yu., Zobov K. V., Bardakhanov S. P., Zavyalov A. P., Chakin I. K. Application of the Method of Evaporation of a Substance by High-Energy Electron Beam to Produce Tungsten Nanopowder. Siberian Journal of Physics, 2019, vol. 14, no. 4, p. 17–27. (in Russ.) DOI 10.25205/2541-9447-2019-14-4-17-27

The method of producing nanopowder by evaporation by a high-energy electron beam has a great potential for refractory substances, since the electron beam makes it possible to obtain high the power density in the interaction spot is not more than 3–4 cm2 and, as a result, high temperature gradients. The accelerator and electron beam have a high efficiency of transferring energy from the power grid to evaporation (up to 70 %). The electron beam does not introduce pollution and is not selective to the material. Work specifics with an electron accelerator is associated with radiation caused by electron deceleration and high temperatures. These phenomena greatly complicate the monitoring of processes occurring in the evaporation zone. Therefore, at present, the method requires development and adaptation to specific materials. In this work, we studied the process of obtaining nanosized tungsten powder by the indicated method. Experiments were tested that allow obtaining data on the processes of nanopowder synthesis by calorimetry of the evaporation zone and measurements of the radiation level near it. The technology was developed and the parameters of the obtained tungsten nanopowders were determined. Showing ways to increase productivity This method is applied to tungsten.

Keywords
nanopowder, tungsten, evaporation, electron beam, electron accelerator, radiation

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Physics of a Fluid, Neutral and Ionized Gases

Grek G. R., Katasonov M. M., Kozlov V. V., Kornilov V. I., Kryukov A. V., Sadovskiy I. A. Control of the Laminar-Turbulent Transition on the Wing Profile by Distributed Suction through a Finely Perforated Surface. Siberian Journal of Physics, 2019, vol. 14, no. 4, p. 28–54. (in Russ.) DOI 10.25205/2541-9447-2019-14-4-28-54

The results of experimental investigations of the influence of distributed suction through a finely perforated section of a symmetric airfoil on the spatial development of disturbances in the boundary layer are presented. It was found that distributed suction reduces by 10 times the intensity of natural disturbances of the boundary layer and by 20 times the intensity of artificial disturbances generated by an external acoustic field. A spectral analysis of disturbances showed that suction reduces the intensity of high-frequency fluctuations for both natural and forced disturbances. It was found that the distributed suction affects the average flow – when the suction is on, the separation of the boundary layer near the trailing edge of the wing is eliminated. It was found that distributed suction significantly affects the mean flow, up to eliminating the boundary-layer separation near the trailing edge of the wing.

Keywords
boundary layer, linear stability, Tollmien – Schlichting waves, distributed suction, disturbance spectrum

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Suslov D. A., Litvinov I. V., Shtork S. I., Gorelikov E. Yu. The Influence of Transient Regimes on Unsteady Vortex Phenomena in the Model of the Draft Tube of the Hydraulic Turbine. Siberian Journal of Physics, 2019, vol. 14, no. 4, p. 55–68. (in Russ.) DOI 10.25205/2541-9447-2019-14-4-55-68

This article is devoted to study the swirling flow with the formation of the precessing vortex core (PVC) in the cone of the model of the draft tube of the hydraulic turbine. The experiments were carried out on the aerodynamic set-up both in stationary and in transient regimes of operation of the hydraulic turbine. The hydraulic turbine operating conditions were varied by continuously changing the flow rate at a constant rotor speed. The formation of the PVC in the flow and the maximum level of pressure pulsations in the regime modeling the partial load regime of a turbine are revealed. The boundaries of the occurrence of the PVC effect are determined with varying rotor speed and air flow rate. It was found that the dependence of the PVC lifetime in transition regimes correlate with the transition time. It was shown that the velocity profiles in transient conditions change quasistatically between the operation regime with partial loading of the turbine and the regime of the highest efficiency of the turbine.

Keywords
swirling flow, precessing vortex core, draft tube, transient regime of the hydraulic turbine

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Shaykin A. P., Galiev I. R. Influence Intensity Turbulence on the Width of the Zone Chemical Reactions and Speed Distribution of Methane-Hydrogen Flame. Siberian Journal of Physics, 2019, vol. 14, no. 4, p. 69–73. (in Russ.) DOI 10.25205/2541-9447-2019-14-4-69-73

The prospects using methane-hydrogen fuel in power plants are shown. The effect of turbulence intensity on propagation velocity and width of the zone of chemical reactions methane-hydrogen flame in combustion chamber of variable volume is investigated. The article shows that effect of turbulence intensity on propagation velocity and flame width depends on fuel excess coefficient. During combustion of stoichiometric fuel-air mixtures, an increase in turbulence leads to a more noticeable increase in flame velocity than when burning poor and rich mixtures. It was experimentally found that increase in intensity of turbulence leads to a noticeable change in width of the flame only when burning poor and rich fuel-air mixtures. Processing of the results of foreign and domestic scientists has shown validity of our laws for combustion chambers of different designs using different hydrocarbon fuels. The results of the work can be used in design and debugging of energy-efficient and low-emission combustion chambers.

Keywords
flame propagation velocity, width of chemical reaction zone, intensity of turbulence, hydrogen, hythane, combustion chamber, flame

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Prokhorov E. S. To the Computation of Equilibrium States of Hydrocarbon Combustion Products under the Lack of Oxygen. Siberian Journal of Physics, 2019, vol. 14, no. 4, p. 74–81. (in Russ.) DOI 10.25205/2541-9447-2019-14-4- 74-81

In this paper, we propose a unified approach to the computation of equilibrium states of hydrocarbon combustion products under the lack of oxygen when both gaseous and condensed carbon phases can appear simultaneously among the components of chemical reaction. One of the principles forming the basis of the approach is that the particles of a condensed substance are “large molecules” consisting of a great number of normal molecules. To illustrate the feasibility of the formulated approach, the problem of explosion of reacting gas mixture in a volume has been numerically solved. The computations have been performed for oxy-acetylene and air- acetylene mixtures.

Keywords
combustion products, chemical equilibrium, carbon condensation

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Solid-State and Semiconductor Physics, Physics of Nanostructures

Rubtsova N. N., Borisov G. M., Ledovskikh D. V. Investigation of Femtosecond IR Radiation Two-Photon Absorption by Pump-Probe Method in GaAs (001) Plate Reflection. Siberian Journal of Physics, 2019, vol. 14, no. 4, p. 82– 90. (in Russ.) DOI 10.25205/2541-9447-2019-14-4-82-90

The reflection of probe infrared femtosecond radiation pulses from a gallium arsenide substrate of the (001) orientation in the presence of more powerful pump pulses of the same radiation with a peak power of up to 1 GW/cm2 was investigated. A Yb³⁺:KY(WO₄)₂ laser with a central wavelength of 1 035 nm, a repetition rate of 70 MHz, a pulse duration of 130 fs, and an average power of not more than 0.9 W worked in the GaAs transparency region. The experimental dependence of the recorded signal on the pump radiation intensity is in qualitative agreement with the model dependence for two-photon absorption. The results are important for the correct interpretation of reflectivity kinetics of quantum wells.

Keywords
two-photon absorption, pump-probe, femtosecond radiation pulses

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Chernyshev V. А., Arkhipov A. V. The Crystal Structure of Rare-Earth Impurity Centers R³⁺ in MeF₂: ab initio Calculation. Siberian Journal of Physics, 2019, vol. 14, no. 4, p. 91–102. (in Russ.) DOI 10.25205/2541-9447-2019-14-4-91-102

Ab initio calculations of the impurity centers R³⁺ (R = La – Lu) in CaF₂ were carried out. The calculations were performed by using hybrid functional which takes into account both local and nonlocal (at the Hartree – Fock formalism) exchange. The crystal structure of impurity centers was investigated. The distance “rare-earth ion – ligand”, the radial and angular coordinates of the ions at several coordination spheres near to the impurity ion are determined. Calculations were carried out in the program CRYSTAL17, designed to simulate periodic structures within the MO LCAO approach.

Keywords
rare-earth impurity centers, ab initio calculations, fluorides

91

Chemical, Biological and Medical Physics

Synchrotron Radiation: Generation and Application

Andysheva E. V., Chankina O. V., Khramova E. P., Krestov P. V., Rakshun Ya. V., Sorokoletov D. S. Comparative Study of Element Composition of Species of the Genus Dasiphora (Rosaceae) in the Primorsky Region and Republic of Buryatia. Siberian Journal of Physics, 2019, vol. 14, no. 4, p. 103–117. (in Russ.) DOI 10.25205/2541-9447-2019-14-4-103-117

Element composition was determined in the aboveground organs (leaves and stems) of plants of four species of the genus Dasiphora: D. fruticosa, D. parvifolia, D. mandshurica, D. gorovoii grown in the Primorsky Territory and Republic of Buryatia. The results were compared with two taxa (D. davurica and the variety D. davurica var. flava) which had been studied earlier. Content of 21 elements in the aboveground organs and samples of soil from sites of the plant collection was analysed by the method of X-ray fluorescence analysis using synchrotron radiation (SRXRF). For the first time, composition and content of the elements were determined for a new taxon D. gorovoii. The highest total content of the macroelements (K, Ca) was found in the aboveground organs of the two taxa: D. davurica and D. davurica var. flava; the highest content of the microelements was determined in the aboveground organs of D. gorovoii, D. mandshurica, and D. fruticosa. We found that each species had a characteristic concentration of elements.

Keywords
element composition, X-ray analysis using synchrotron radiation, Dasiphora, Rosaceae, Russian Far East, Eastern Siberia

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Instructions to Contributors

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