Перегляд за автором "Sashkova, Y. V."
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Публікація Localized field enhancement in slow-wave modes of modified Bragg waveguide(IEEE, 2017) Odarenko, E. N.; Sashkova, Y. V.; Shmat'ko, A. A.Modified scheme of Bragg reflection waveguide with additional layers between the hollow core and cladding is considered. Dispersion diagrams are calculated on the base of dispersion equations solutions for ordinary and modified Bragg waveguides. Slow-wave regimes are considered for both kinds of structure. Electric field spatial distributions for localized slowwave modes of Bragg reflection waveguide are obtained. It is shown that modified scheme of Bragg waveguide provides the enhanced localization of the surface modes field in the hollow core. Therefore modified Bragg waveguide is the promising electrodynamic system not only for laser-driven accelerators but also for the vacuum electron devices where usual slow-wave structures are unconvenient.Публікація New Technologies of Laser Hardening of Parts of Fuel Equipment(Sumy State University, 2023) Hnatenko, O. S.; Afanasieva, O. V.; Lalazarova, N. O.; Kurskoy, Yu. S.; Odarenko, E. N.; Sashkova, Y. V.; Ivanchenko, O. V.Laser thermal hardening of steel (laser hardening) consists in heating a section of the steel surface above the phase transition temperature by laser radiation, followed by rapid cooling due to heat removal. As a result of this treatment, martensite is formed – a saturated solid carbon solution in α-iron. For laser hardening, gas CO2 lasers, solid-state (mainly Nd:YAG) and fiber lasers with a power of 0.5 kW or more are most often used. Optical systems for deploying and scanning the beam allow you to harden large areas of the surface with maximum efficiency. Not all products need processing of significant areas. Measuring and cutting tools, parts of fuel equipment, pump injectors are subject to significant abrasive wear of individual small areas. Less powerful lasers can be used to process them. There are no results of using low power pulsed lasers (up to 20 W) for surface hardening of steel products. The purpose of this work is to determine the modes of surface hardening of parts and tools made of carbon and alloy steels using low power pulsed solid-state YAG lasers. For laser hardening, a solid-state YAG laser with a power of 5 W (diode pumping, radiation wavelength = 1.064 µm, pulsed mode) was used. The use of a nonlinear crystal made it possible to obtain UV radiation from λ = 0.355 µm (third harmonic). Processing with single pulses and multi-pulse processing with short pulses were investigated. Thermal hardening was carried out on carbon and alloy steels of various compositions: 20, 45, У12, Р6M5, Р9, ШХ15, structural and tool steels for the purpose. The possibility of hardening by UV radiation was evaluated on steels 20, 45, У12 and ЩХ15. The efficiency of laser thermal hardening was evaluated by measuring microhardness. For surface hardening of products, where partial melting of the surface is possible, low-power pulsed lasers can be used. Laser hardening by UV radiation is a promising direction for thermal hardening of steels without surface melting. Hardening with a low-power laser is expedient for hardening parts of fuel equipment.Публікація Physical and Technological Principles of Processing Steel with UV Laser Radiation(СумДУ, 2023) Hnatenko, O. S.; Afanasieva, O. V.; Lalazarova, N. O.; Odarenko, E. N.; Sashkova, Y. V.; Ivanchenko, O. V.; Kurskoy, Yu.S.The main purpose of the article is to study the hardening of steel using non-standard wavelengths of laser radiation. The physical principles of the interaction of laser radiation with matter are also described. Experiments were carried out on hardening steel with a UV laser (wavelength 355 nm). The following experiments and a comparative analysis of volumetric hardening of steel with cooling in water, hardening with a YVO4 laser beam with (λ = 1.06 μm and hardening with a YVO4 laser beam with (λ = 0.355 μm. The studies were carried out on structural steel 45 and tool steels У12 and Р6M5. In the course of the research, new interesting scientific results were obtained: the study of the microstructure of U12 steel samples using an electron microscope showed that the martensite formed during quenching by UV radiation is more dispersed, as a result of which it can be concluded that such processing can lead to the production of surface nanostructures up to 100 nm in size. However, due to the low productivity and low power of UV radiation, the proposed steel hardening can be recommended for measuring and cutting tools.Публікація Simulations of the Plane Wave Scattering by Multilayer Cylindrical Structure(Institute of Radiophysics and Electronics National Academy of Sciences of Ukraine, 2014) Sashkova, Y. V.; Odarenko, E. N.In this paper the important problem of the electromagnetic field spatial distribution visualization for the wave scattered by a multilayer dielectric cylinder is considered. The solution of this problem allows investigating of the focusing properties of such structures and to optimize their parameters and dimensions.Публікація The Effect of Additional Layers Parameters on the Modifided Bragg Waveguide Characteristics(IEEE, 2017) Sashkova, Y. V.; Odarenko, E. N.Bragg waveguide with additional layers between hollow core and periodic cladding is considered. On the base of dispersion equation solutions dispersion diagrams are obtained. The transversal spatial distributions of the electric field intensity are shown. The characteristics of Bragg waveguide respect to additional layer thickness and permittivity are considered. It is shown that increase of additional layers thickness results in increase of slow-waves number. Also field intensity decay in channel is reduced. Number of slow-waves increases respect to additional layers permittivity too. But distribution of the electric field intensity in the channel changes insignificantly. So one can tune additional layers parameters to get expected Bragg waveguide characteristics.Публікація Visualization of the Monochromatic Plane Wave Scattering by Multilayer Lens(IEEE, 2016) Sashkova, Y. V.; Odarenko, E. N.The scattering of electromagnetic wave by the N-layer dielectric cylinder is considered in this work. A universal simulation project is developed for determine of the characteristics of the field scattered by a multilayered cylinder and visualization of the electric field spatial distribution. Amplitude distributions of the electric field for different values of the inner cylinders diameters, material parameters and incident radiation wavelength are obtained.