SIBERIAN JOURNAL OF PHYSICS. Scientific Journal. 2020. V15, i 1

 

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

 

Baranov G. N., Bogomyagkov A. V., Levichev E. B., Sinyatkin S. V. Magnet Lattice Optimiza-tion for Novosibirsk Fourth Generation Light Source SKIF // Siberian Journal of Physics, 2020, vol. 15, no. 1, p. 5–23. (in Russ.) DOI 10.25205/2541-9447-2020-15-1-5-23

We study magnetic lattice and optimize parameters for the fourth generation light source SKIF (Russian acronym of Siberian Circular Photon Source) to be built in Novosibirsk. We consider several lattice cells to achieve both low emittance and large dynamic aperture. The resulting lattice provides the natural emittance of the electron beam of 75 pm for the beam energy of 3 GeV and the orbit circumference of 476 m. Only two families of chromatic sextupoles give the dynamic aperture and energy bandwidth enough for both good beam lifetime and simple effective injection.

Keywords
synchrotron light source, magnetic lattice, beam emittance, SR brilliance, dynamic aperture

 

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Arzhannikov A. V., Samtsov D. A., Sinitsky S. L., Stepanov V. D. Angular Divergence of Elec-trons in Generating Two Ribbon Beams in a Single Accelerating Diode (Simulation, Ex-periment) // Siberian Journal of Physics, 2020, vol. 15, no. 1, p. 24–41. (in Russ.) DOI 10.25205/2541-9447-2020-15-1-24-41

The paper presents the results of numerical simulation and experimental studies of the generation of two ribbon beams in an accelerating diode with magnetic insulation at a diode voltage of ~ 0.7 MeV and a current of 10 kA in it. Model-ing is implemented using the Particle CST Studio package. The experiments were conducted on the U-3 accelerator of the ELMI installation. In calculations with three-dimensional geometry corresponding to the experiments, the distribu-tion of electron velocities over the pitch angle at the exit of the beams from the diode under the conditions of an inho-mogeneous magnetic field with an induction of about 1 T was obtained. These calculated data were confirmed in an experiment in which, using a sensor with seven recording channels, a distribution function of the velocity of electrons with a characteristic width at half maximum of 0.03 rad was obtained. Using the GEANT4 software package in pro-cessing measurement results with this sensor gives confidence in the correctness of the obtained distribution function.

Keywords
electron beam, distribution function of magnetized electrons, angular spread detector

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Physics of a Fluid, Neutral and Ionized Gases

 

Lysenko V. I., Gaponov S. A., Smorodsky B. V., Kosinov A. D., Yaroslavtsev M. I. Stability of Supersonic Boundary Layer on the Sublimation Surface // Siberian Journal of Physics, 2020, vol. 15, no. 1, p. 42–61. (in Russ.) DOI 10.25205/2541-9447-2020-15-1-42-61

Theoretical investigation of the supersonic flat-plate boundary-layer properties under conditions of the surface material sublimation has been performed for Mach number M = 2. Naphthalene (C10H8) was chosen as the substance for the sublimation coating. Performed computations show that with increasing surface temperature due to stagnation temperature increase, the mass flow rate of naphthalene evaporation increases. Calculations performed on the basis of linear stability theory show that such an increase of evaporation leads to a noticeable decrease of the local growth rates of unstable perturbations in the boundary layer. It is found that stabilization of the boundary layer by the surface coating sublimation occurs with increasing temperature of the sublimation coating, reaching a maximum near the triple point temperature of the sublimation material. The carried out experiments confirmed the stabilizing effect of surface sublimation.

Keywords
supersonic boundary layer, hydrodynamic stability, laminar-turbulent transition, binary gas mixture, sublimation

 

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Abdurakipov S. S., Dulin V. M. Stability Analysis of Round Jets with Density Gradient // Siberian Journal of Physics, 2020, vol. 15, no. 1, p. 62–79. (in Russ.) DOI 10.25205/2541-9447-2020-15-1-62-79

Using Chebyshev spectral collocation method, the temporal and spatial stability analysis of a round jet with tangential velocity profile and transverse density gradient is carried out. The characteristic frequencies, wave numbers and eigen modes of the most unstable normal perturbations are analyzed. It is concluded that considering transverse density gradient in most cases leads to decrease in the growth rates and phase velocities of all unstable modes. It is shown that the relations between the phase and group velocities obtained from the temporal and spatial stability analysis of round jet turn out to be valid only for large shear layer thicknesses.

Keywords
stability analysis, round jet, spectral collocation method

 

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Zudov V. N., Shmagunov O. A. Initiation of Ignition of a Combustible Mixture in a Flow by Local Energy Supply // Siberian Journal of Physics, 2020, vol. 15, no. 1, p. 80–89. (in Russ.) DOI 10.25205/2541-9447-2020-15-1-80-89

A direct numerical simulation of the influence of a local energy release region on the development of the combustion propagation process in a high-speed flow of homogeneous fuel-air mixture (Н2 + air) is carried out. The mathematical model of the energy source describes the physical phenomena characteristic for pulsed energy supply using laser radiation. The energy supply and ignition are modeled taking into account a given kinetic scheme. The results on the spatial and temporal evolution of the ignition region are presented. The dependence of the position of the ignition region on the flow velocity is investigated.

Keywords
optical discharge, homogeneous combustion, numerical simulation, nonequilibrium flow

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Solid-State and Semiconductor Physics, Physics of Nanostructures

 

Kovalyov A. A. Modes of Travelling Electromagnetic Waves within Cylinders // Siberian Journal of Physics, 2020, vol. 15, no. 1, p. 90–97. (in Russ.) DOI 10.25205/2541-9447-2020-15-1-90-97

An algorithm is proposed for numerical calculation of traveling electromagnetic wave modes for solid and hollow solid state cylinders. Complex eigenvalues are defined for angular parameters characterizing emissive modes and whis-pering gallery modes (WG-mode). The polar component imaginary parts of the wave vectors are found for all modes, including WG modes. The calculation is carried out for the fixed cylinder sizes. The field distributions are calculated inside the cylinders. The dependence of the mode parameters on the extinction coefficients of the cylinder material was studied. The ratio of the density of energy fluxes for the radial and polar directions shows a sharp change when passage from the emissive modes to WG modes.


Keywords
traveling electromagnetic wave, whispering gallery mode

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Chemical, Biological and Medical Physics

Synchrotron Radiation: Generation and Application

 

Mikhailenko M. A., Sharafutdinov М. R., Eltsov I. V., Trenikhin M. V., Tolochko B. P. Inves-tigation of Complexation of Bismuth Potassium Citrate with Polysaccharides // Siberian Journal of Physics, 2020, vol. 15, no. 1, p. 100–107. (in Russ.) DOI 10.25205/2541-9447-2020-15-1-100-107

The interaction of potassium bismuth citrate (PBC) with polysaccharides of various structures – dextran (linear) and arabinogalactan (branched) was investigated. The NMR method revealed the donor-acceptor character of the interac-tion of dextran with PBC in water solutions. Synchrotron radiation and transmission electron microscopy was show the formation of the anisotropic PBC-nanocrystals the covered of dextran layers.


Keywords
potassium bismuth citrate, dextran, arabinogalactan, synchrotron radiation

 

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Educational and Methodical Provision of Teaching of Physics

 

Arzhannikov A. V., Knyazev B. A. First Online Physics Olympiads between United Russian-American High-School Teamsв // Siberian Journal of Physics, 2020, vol. 15, no. 1, p. 108–138. (in Russ.) DOI 10.25205/2541-9447-2020-15-1-108-138

The article is dedicated to the twentieth anniversary of two Internet physics olympiads organized by the Physics Department of Novosibirsk State University, in which senior pupils from Russia and the USA participated. For the time when before the advent of popular social networks there were a few more years when the currently popular messengers were not yet widespread, the organization of such competitions was technically and organizationally far from a trivial task. It was also necessary to overcome the problem of different programs and different levels of school physics teaching in Russia and the USA, as well as the problem of the language barrier. All these tasks were successfully solved by the joint efforts of the Russian and American organizing committees, and in 1999 the competitions Novosi-birsk – San Diego and in 2000 Novosibirsk – St. Petersburg – San Diego – Seattle were held. A successful invention that allowed equalizing the chances of teams and replacing interethnic rivalry with cooperation was the idea to hold competitions between international teams, consisting of an equal number of Russian and American schoolchildren communicating with each other via direct video communication. Sets of tasks were prepared for the olympiads, both ordinary, written, and video clips with tasks-demonstrations. The latter have been particularly successful in resolving the problem of the language barrier. The great help in conducting these two Olympiads was the many years of experi-ence gained by NSU during the All-Siberian Olympiads and the idea of the demonstration tasks used in entrance ex-aminations at the Physics Department of NSU. We present in this article both the content of the tasks of the Olympi-ads and the responses of the domestic and American press to the events described

Keywords
physics teaching, physics olympiads, tasks on physics

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Instructions to Contributors

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