SIBERIAN JOURNAL OF PHYSICS 2021. Volume 16, № 2

SIBERIAN JOURNAL OF PHYSICS. Scientific Journal. 2021. V16, i 2
Radiophysics and Electronics
Bazarova A. S., Sychev R. S., Bazarov A. V., Atutov E. B., Bashkuev Yu. B. Seasonal Distribution of the Radio Wave Refraction Index over the Territory of Buryatia. // Siberian Journal of Physics, 2021, vol. 16, no. 2, pp. 5–13. (in Russ.) DOI 10.25205/2541-9447-2021-16-2-5-13 The values of the atmospheric refraction index N for ultra-short radio waves for the territory of Buryatia according to the data of meteorological stations were calculated. The monthly average values N contours maps for the central months of the seasons of 2020 were constructed. It is shown the humidity of Lake Baikal and the relief significantly influence N. On average, the values of the refractive index near the lake are 20–30 N-units higher. It is revealed the monthly average N values have maxima in winter and summer with minimums in spring and autumn, with the main maximum occurring in July. Keywords radio meteorology, atmospheric refraction index, seasons of year, relief Funding The Ministry of Education and Science of the Russian Federation, budget project no. 0270-2021-0004 “Development of ELF-VLF-LF-MF and VHF radio waves propagation fundamental foundations in inhomogenious impedance channels” supported this work	5
Physics of a Fluid, Neutral and Ionized Gases
Pavlenko A. M., Bykov A. V., Zanin B. Yu., Katasonov M. M. Study of Flow around a Trapezoidal Model of a Small-Sized UAV into Turbulent Wake. Siberian Journal of Physics, 2021, vol. 16, no. 2, pp. 14–28. (in Russ.) DOI 10.25205/2541-9447-2021-16-2-14-28 Investigations of the structure of the flow near the surface of a trapezoidal model of a small unmanned aerial vehicle were carried out when it enters a narrow turbulent wake. All experimental data were obtained in a wind tunnel at subsonic flow velocities. A feature of the work was that the study of the flow around the model was carried out at full-scale (flight) Reynolds numbers. Using the soot-oily visualization method, data on the features of the flow around the model were obtained, taking into account such factors as the angle of attack, the presence and absence of a source of external disturbances that generated a turbulent wake. The experiments were carried out in two flow regimes: at a zero angle of attack, when there are local separation bubbles on the wing, and at a large (supercritical) angle of attack of 18 degrees, when there is a global stall of the flow from the leading edge. It was shown that the turbulent wake has a significant effect on the nature of the flow near the model surface in both cases. Local separation bubbles gradually decrease in size with a decrease in the distance between the sources of disturbances and the wing. Large-scale vortices significantly decrease in geometrical dimensions and shift towards the side edges in the event of a global stall of the flow, thereby increasing the region of the attached flow on the model surface. Keywords global flow stall, local separation bubble, turbulent wake, free stream disturbances, three-dimensional boundary layer, trapezoidal flying wing, UAV, natural Reynolds number Funding This work was carried out within the framework of the Program of Fundamental Scientific Research of State Academies of Science for 2021–2023 (project no. 121030500149-8)	14
Akinin S. А., Starov A. V. Specific Features of Flow on Compression Surfaces of a Convergent Air Intake. // Siberian Journal of Physics, 2021, vol. 16, no. 2, pp. 29–40. (in Russ.) DOI 10.25205/2541-9447-2021-16-2-29-40 The results of computational and experimental studies of a model of a hypersonic convergent air intake are presented. Experimental studies were carried out in a hot-shot wind tunnel IT-302M SB RAS at a Mach number M = 5.7 and an angle of attack a = 4 °. Numerical modeling was carried out in a three-dimensional setting in the ANSYS Fluent soft-ware package. The calculations were carried out in 4 versions using different turbulence models: k-e standard, RNG k-e, k-w standard and k-w SST. The features of the flow structure are established. The pressure distributions on the compression surfaces and in the air intake channel are obtained. The separated flow at the entrance of the inner channel was studied. It was found that the use of various turbulence models has a significant effect on the size and position of separation. The best agreement between the calculated and experimental data on the level of static pressure was shown by the variant with the k-e standard turbulence model. Keywords hypersonic air intake, convergent compression surface, shock wave, boundary layer, separation, numerical simulation, turbulence model, experiment Funding The research was carried out within the framework of the Program of Fundamental Scientific Research of the state academies of sciences in 2013–2020 (project no. АААА-А17-117030610126-4)	29
Lysenko V. I., Smorodsky B. V., Kosinov A. D. Development of Disturbances in the Supersonic Boundary Layer under Helium Injection from the Surface. // Siberian Journal of Physics, 2021, vol. 16, no. 2, pp. 41–47. (in Russ.) DOI 10.25205/2541-9447-2021-16-2-41-47 Experiments on the influence of distributed injection of helium on the development of the supersonic boundary layer unstable disturbances have been performed. It is revealed, that injection of helium in a certain range of blowing mass flow rate, leads to a certain decrease of spatial amplification rates of natural disturbances. Keywords supersonic boundary layer, development of disturbances, helium Funding The research was carried out within the state assignment of Ministry of Science and Higher Education of the Russian Federation (project no. 121030500161-0)	41
Zudov V. N., Tupikin A. V. Effect of an Electric Field on an Optical Breakdown in the Air Stream. // Siberian Journal of Physics, 2021, vol. 16, no. 2, pp. 48–58. (in Russ.) DOI 10.25205/2541-9447-2021-16-2-48-58 Experimental data on the effect of an electric field on the plasma of an optical discharge in an air flow have been obtained. Two configurations of an external electric field under the action of an optical discharge on the plasma are considered. To create an electric field, flat (the field along the beam and across the flow) and ring electrodes (the field across the laser beam and along the flow) were used. It was found that there are two modes of combined discharge (optical and electrical). When the field was created symmetrically with respect to the flow axis, an electrical breakdown was observed from the nozzle exit (positively charged electrode) to the focusing point of the laser beam, while no streamers were observed in the optical discharge wake. In another case, an electric discharge is realized between flat electrodes simultaneously with optical breakdown. In a field of constant strength above 3 kV/cm, the presence of an optical discharge plasma promoted electrical breakdown of the medium. In this case, the parameters of the electrical breakdown depended on the shape of the electrodes, the polarity of the applied voltage, and the air flow rate. Keywords experimental simulation, laser radiation, optical discharge, electric field, electrical discharge, air stream Funding This work was carried out within the framework of a state assignment (state registration no. 121030500157-3) and with partial financial support from the Russian Foundation for Basic Research (grant no. 19-08-00304)	48
Prokhorov E. S. Melting Point of Carbon Particles behind the Gas Detonation Front. // Siberian Journal of Physics, 2021, vol. 16, no. 2, pp. 59–70. (in Russ.) DOI 10.25205/2541-9447-2021-16-2-59-70 A mathematical model of gas detonation of fuelenriched mixtures of hydrocarbons with oxygen has been formulated, which makes it possible to numerically study the equilibrium flows of detonation products in the presence of free carbon condensation. Reference data for graphite were used to describe the thermodynamic properties of carbon condensate. The calculations are compared with the known results of experimental studies in which, when detonating an acetylene-oxygen mixture in a pipe closed at one end, it is possible to obtain nanoscale particles from a carbon material with special properties. It is assumed that the melting point of such a material is lower than that of graphite and is about 3100 K. Only with such an adjustment of the melting temperature, the best agreement (with an accuracy of about 3 %) was obtained between the calculated and experimental dependence of the detonation front velocity on the molar fraction of acetylene in the mixture. Keywords gas detonation, chemical equilibrium, carbon condensation	59
Pinakov V. I. The Acoustic Nature of “Storm Nose”, “Supercell” Vortices and Tornadoes. // Siberian Journal of Physics, 2021, vol. 16, no. 2, pp. 71–80. (in Russ.) DOI 10.25205/2541-9447-2021-16-2-71-80 The process of cumulonimbus cloud Cb calvus formation in the middle latitudes of real atmosphere is analyzed in this work. Its transformation from initial lifecycle stage to “maturity” undergoes due to the formation of the waveguide called “aerial acoustic channel” in the troposphere near the level of temperature minimum that is close to 2 km altitude. This “aerial acoustic channel” can be considered as analog of “deep sound channel” that corresponds to the minimal sound speed level. Tropospheric “channel” related to the thermal inversion zone is almost unlimited horizontally. Synchronous generation of two compression waves (ascending one above Cb and descending one inside Cb) is caused by Cb calvus dome ascension. The first one can provoke the aerodynamic draft previously unexplained. The second one results in the growth of its “storm nose” and in the axial and peripheral descending mechanisms in Cb. The penetration of Cb into stratosphere results in the destruction of dynamic balance around Cb top and hence in its unloading in the descending decompression wave. Here the air cools down to the “dew point” in the place of conjugation with parental cloud – due to Snellius law it results in the formation of aerosol “vortex” as condensation front; this “vortex” has calculated value of its generatrix against vertical. Due to D. Snow’s criterion, this vortex forms either “supercell” vortex or tornado vortex. Keywords condensation front, Snellius law, mesocyclone, subcritical slip angle, wave pressure, phase velocity	71
Solid-State and Semiconductor Physics, Physics of Nanostructures
Kolyako A. V., Pleshkov A. S., Tretyakov D. B., Entin V. M., Ryabtsev I. I., Neizvestny I. G. Investigation of Long-Term Stability of Single-Photon Quantum Key Distribution in a Polarization Coding Scheme. // Siberian Journal of Physics, 2021, vol. 16, no. 2, pp. 81–93. (in Russ.) DOI 10.25205/2541-9447-2021-16-2-81-93 Experimental results demonstrating long-term stability of the operation of our atmospheric quantum cryptography setup using the BB84 protocol and polarization coding are presented. It was shown that the “sifted” quantum key distribution rate and the quantum bit error rate in the key remained constant for 1 hour and were equal to 10 kbit/s and 6.5 %, respectively, at a distance between the transmitter and the receiver equal to 20 cm. Theoretical dependences of the secret quantum key generation rate on a quantum channel transmission coefficient for single-photon detectors, which were used in this experiment, and for new detectors with a reduced level of dark pulses are given. Keywords quantum cryptography, BB84 protocol, polarization coding, single-photon detectors Funding This work was supported by A. V. Rzhanov Institute of Semiconductor Physics SB RAS and Novosibirsk State University	81
Educational and Methodical Provision of Teaching of Physics
Zaikin A. D., Suhanov I. I. The Physics Laboratory Works – Individualized Computer Simulations. // Siberian Journal of Physics, 2021, vol. 16, no. 2, pp. 94–104. (in Russ.) DOI 10.25205/2541-9447-2021-16-2-94-104 The physics laboratory-works creating and operating computer simulations experience is described. A significant amount of laboratory works can be classified as a “black box”. The studied physical phenomenon is hidden from direct observation, the control is carried out by means of electrical measuring devices. It is difficult to distinguish physical reality from its imitation when performing such work, so the virtualization of this one does not require realistic images. The schematic representation of the laboratory installation greatly simplifies the process of creating a simulator. A unique set of installation parameters is formed for each student performing laboratory work on the simulator, which contributes to the independence of the student's work. These parameters are stored in Google Sheets. Their transfer to the laboratory work’s html-template is carried out in encrypted form through the Google Apps Script service. Virtual laboratory work is implemented as a cross-platform web application. Keywords laboratory assignment, simulator, Google Sheet, Google Apps Script	94
Instructions to Contributors	105
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