East European Journal of Physics https://periodicals.karazin.ua/eejp <p>EEJP is an international peer-reviewed journal devoted to experimental and theoretical research on nuclear physics, cosmic rays and particles, high-energy physics, solid-state physics, plasma physics and controlled thermonuclear fusion, physics of charged particle beams, plasma electronics, radiation materials science, physics of thin films, condensed matter physics, functional materials and coatings, technical thermophysics and industrial power, medical physics and physical technologies in an interdisciplinary context.</p> <p>EEJP registered by the order of Ministry of Education and Science of Ukraine <strong>No. 1643 of 28.12.2019</strong>, and included in the list of scientific professional Editions of Ukraine (<strong>category “A”, specialty: 104, 105</strong>), in which results of dissertations for obtaining Ph.D. and Dr. Sci. degrees in physical and mathematical sciences can be published.</p> <p>The Journal is a part of the <strong>Web of Science Core Collection (ESCI)&nbsp;</strong>scientometric platform and indexed by&nbsp;<strong>SCOPUS</strong>.</p> <p>&nbsp;</p> V.N. Karazin Kharkiv National University en-US East European Journal of Physics 2312-4334 <p>Authors who publish with this journal agree to the following terms:<br><br></p> <ol type="a"> <ul> <li class="show">Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a&nbsp;<a href="http://creativecommons.org/licenses/by/4.0/" target="_new">Creative Commons Attribution License</a>&nbsp;that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.</li> </ul> </ol> <ol type="a"> <ul> <li class="show">Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.</li> </ul> </ol> <ol type="a"> <ul> <li class="show">Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work (See&nbsp;<a href="http://opcit.eprints.org/oacitation-biblio.html" target="_new">The Effect of Open Access</a>).</li> </ul> </ol> Study of 14N(γ,np)3α Reaction for Eγ up to 150 MeV https://periodicals.karazin.ua/eejp/article/view/18431 <p>The reaction <sup>14</sup>N(g,np)3a induced by bremsstrahlung photons of endpoint energy E<sub>g</sub><sup>max</sup> = 150 MeV has been investigated using diffusion chamber, which is placed into the magnetic field. The distribution functions of the reaction yield, the energy and momentum of the final particles from Е<sub>g</sub> were measured and it was determined that at Е<sub>g</sub> &gt; 45 MeV, change in the behavior of these functions occurs. The average energy T<sup>aver</sup> was calculated for the particles with the energy falling within a 1 MeV interval of the total kinetic energy T<sub>0</sub>&nbsp;= E<sub>g</sub> ‑ Q, where Q is the energy threshold of the reaction (Q = 19.77 MeV). At T<sub>0</sub> ~ 20 MeV, the dependence of the contributions from T<sup>aver</sup> to T<sub>0</sub> changes sharply. At T<sub>0</sub> &gt; 20 MeV, most of the energy is carried away by nucleons, their relative contribution is equal, and this agrees with the assumption of the quasideuteron interaction mechanism. The momentum distribution distributions for the neutron and proton have a similar form, with a strong shift of the maximum towards higher energies with an increase in the energy of the γ quantum. For a system of 3α‑particles, in each distribution, peak is observed centered at 100 MeV/<em>c</em>, the relative contribution of which smoothly decreases with increasing momentum, and a wide high-energy "tail" appears. The energy and angular correlations of the np‑pair depends on both of the energy Е<sub>g</sub> and the momentum of the system of 3α‑particles.</p> Serhii Afanasiev Copyright (c) 2022 Serhii N. Afanasiev 2022-03-17 2022-03-17 1 5 9 10.26565/2312-4334-2022-1-01 Simulation of Heat Transfer in Single-Crystal Lithium Niobate in Interaction with Continuous-Wave Laser Radiation https://periodicals.karazin.ua/eejp/article/view/18432 <p>The paper presents the simulation results of heat transfer in single-crystal lithium niobate (LiNbO<sub>3</sub>) in the form of cylinder of diameter mm and height mm in interaction with continuous-wave laser radiation with the output power of W and the wavelength of nm. The density of the LiNbO<sub>3</sub> crystal is kg/m<sup>3</sup>; the thermal conductivity along the [001] direction is W/(m×K); the thermal conductivity in the (001) plane is W/(m×K); the specific heat at constant pressure is J/(kg×K); the absorption coefficient is %/cm @ 1064 nm. The laser beam propagates along the optical axis of the crystal. The laser beam intensity profile is represented as a Gaussian function, and the absorption of laser radiation of the single-crystal lithium niobate is described by Beer-Lambert’s law. The numerical solution of the non-stationary heat conduction problem is obtained by meshless scheme using anisotropic radial basis functions. The time interval of the non-stationary boundary-value problem is 2 h 30 min. The results of numerical calculations of the temperature distribution inside and on the surface of the single-crystal lithium niobate at times s are presented. The time required to achieve the steady-state heating mode of the LiNbO<sub>3</sub> crystal, as well as its temperature range over the entire time interval, have been determined. The accuracy of the approximate solution of the boundary-value problem at the <em>n</em>-th iteration is estimated by the value of the norm of relative residual . The results of the numerical solution of the non-stationary heat conduction problem obtained by meshless method show its high efficiency even at a small number of interpolation nodes.</p> Denys O. Protektor Denys O. Lisin Copyright (c) 2022 Denys O. Protektor, Denys O. Lisin 2022-03-17 2022-03-17 1 10 15 10.26565/2312-4334-2022-1-02 An Insight into the Electronic, Optical and Transport Properties of a Half Heusler Alloy: NiVSi https://periodicals.karazin.ua/eejp/article/view/18433 <p>The half-Heusler alloy NiVSi is investigated theoretically by using first-principles calculations based on the density functional theory (DFT). For a better description of the electronic properties, the TB-mBJ potential is used for exchange-correlation potential. The structural, electronic, magnetic, optical and thermoelectric properties was calculated by WIEN2k software. The negative cohesive and formation energies found reveal that the NiVSi is thermodynamically stable. Electronically, the NiVSi is a half-metal with an indirect band gap of 0.73 eV in the spin-down channel whereas the spin up channel is metallic. The total magnetic moment is of 1. Optically, the obtained high absorption coefficient in ultraviolet wavelength range, make the NiVSi useful as effective ultraviolet absorber. Thermoelectrically, a high figure of merit in the p- and n-type region was obtained, what makes this compound very functional for thermoelectric applications. The generation of a fully spin-polarized current make this compound unsuitable for spintronic applications at room temperature, a doping may be a satisfactory solution to improve this property.</p> Djelti Radouan Besbes Anissa Bestani Benaouda Copyright (c) 2022 Djelti Radouana, Besbes Anissa, Bestani Benaouda 2022-03-17 2022-03-17 1 16 25 10.26565/2312-4334-2022-1-03 Level Structure of 58Cu Within Modified Surface Delta-Interaction https://periodicals.karazin.ua/eejp/article/view/18434 <p>The nuclear shell model with modified surface delta interaction MSDI was used to calculate the values of energy levels of the copper nucleus <sup>58</sup>Cu. The neutron and proton in the model space <em>1p<sub>3/2</sub> 0f<sub>5/2</sub> 1p<sub>1/2</sub></em> of the copper nucleus occur outside the closed core <sup>56</sup>Ni. This research investigates the excitation energy and angular momentum. As a consequence, theoretical approaches are used to uncover a collection between excitation energies and classical coupling angles θ<sub>a,b</sub> at various orbitals. Finally, we demonstrate that our results are supported by experimental evidence: Excitation energies have two major functions, both of which are influenced by classical coupling angles but are unaffected by angular momentum I.</p> Dalal N. Hameed Ali K. Hasan Copyright (c) 2022 Dalal N. Hameed, Ali K. Hasan 2022-03-17 2022-03-17 1 26 31 10.26565/2312-4334-2022-1-04 Study of Electrostatic Ion-Cyclotron Waves in Magnetosphere of Uranus https://periodicals.karazin.ua/eejp/article/view/18436 <p>In this manuscript, the method of characteristics particle trajectories details used and the dispersion relation for the ionosphere of Uranus were being used to investigate electrostatic ion-cyclotron waves with parallel flow velocity shear in the presence of perpendicular inhomogeneous DC electric field and density gradient. The growth rate has been calculated using the dispersion relation. Electric fields parallel to the magnetic field transmit energy, mass, and momentum in the auroral regions of the planetary magnetosphere by accelerating charged particles to extremely high energies. The rate of heating of plasma species along and perpendicular to the magnetic field is also said to be influenced by the occurrence of ion cyclotron waves and a parallel electric field in the acceleration area.</p> Rama S. Pandey Mukesh Kumar Copyright (c) 2022 Rama S. Pandey, Mukesh Kumar 2022-03-17 2022-03-17 1 32 39 10.26565/2312-4334-2022-1-05 Effect of the Relativistic Electron Beam on Propagating Whistler-Mode Wave for Ring Distribution in the Saturn Magnetosphere https://periodicals.karazin.ua/eejp/article/view/18437 <p>Cassini and many investigators reported whistler chorus near Saturn equatorial plane moving outwards. Whistler can propagate when going to high latitude and can alter its characteristics while interacting resonantly with available energetic electrons. Here investigating wave for a relativistic beam of the electron. It is observed and reported by Cassini Magnetospheric Imaging Instrument (MIMI) that inward radial injection of highly energetic particles is most dominant in Saturn intrinsic magnetosphere. Within this paradigm, an empirical energy&nbsp;dispersion relation for propagated whistler-mode oscillations in quasi Saturn magnetospheric plasma from such a non-monotonous ringed distribution function has been established. The kinetic approach and method of characteristics methodologies were used in the computations, which have been shown to be the best for building perturbed plasma states. The perturbed distribution function was estimated using the unperturbed particle routes. The ring distribution function was used to construct an unexpected growth rate expression for relativistic plasma in the inner magnetosphere. The results from the Saturn magnetosphere have been calculated and interpreted using a range of parameters. Temperature heterogeneity was shown to be a significant source of free energy that aided the propagation of a whistler-mode wave. By raising the peak value, the bulk injection of energetic hot electron injection impacts the growth rate. Growth was also demonstrated to be accelerated when the propagation angle increased. The research contributes to a better understanding of the relationship between wave and particle emissions and VLF emissions on a large scale.</p> E.H. Annex Rama S. Pandey Mukesh Kumar Copyright (c) 2022 E.H. Annex, R.S. Pandey, Mukesh Kumar 2022-03-17 2022-03-17 1 40 46 10.26565/2312-4334-2022-1-06 Study of Structural, Elastic, Thermal and Transport Properties of Ternary X(X=Co, Rh and Ir)MnAs Obtained by DFT https://periodicals.karazin.ua/eejp/article/view/18438 <p>The Density Functional Theory (DFT) with an approximation of generalised gradient is used for the study of elastic, thermodynamic and transport properties and for that of structural stability of ternary Half-Heuslers compounds X(X=Co, Rh and Ir)MnAs. This first predictive study of this compounds determines the mechanical properties such that the compression, shearing, Young modulla and Poisson coefficient without omitting the checking parameters of the nature of these compounds such that hardness, Zener anisotropic facto rand Cauchy pressure. The Pugh ratio and Poisson coefficient have allowed the identification of ductile nature of these compounds. The speed of sound and Debye temperature of these compounds has also been estimated from the elastic constants. The thermodynamic properties have been calculated as well for a pressure interval from zero to 25 GPa. The effect of chemical potential variation on Seebeck coefficient, electric, thermal and electronic conductivities, the power and merit factors have also been studied for different temperatures (300, 600, 900°K), so that these alloys can be better potential candidates for thermoelectric applications.</p> Salim Kadri Tourab Mohamed Berkani Mahièddine Amraoui Rabie Bordjiba Zeyneb Copyright (c) 2022 Salim Kadri, Tourab Mohamed, Berkani Mahièddine, Amraoui Rabie, Bordjiba Zeyneb 2022-03-17 2022-03-17 1 47 57 10.26565/2312-4334-2022-1-07 Characteristics and Optical Properties of Bi2Te2.45Se0.55 Thin Film https://periodicals.karazin.ua/eejp/article/view/18440 <p>Thermally evaporated Bi<sub>2</sub>Te<sub>2.45</sub>Se<sub>0.55</sub> thin films were examined for structural alterations and electrical conductivity. Crystallite size, micro-strain, and dislocations were all calculated using the XRD data. By using transmission electron microscopy, the morphology of thin films was investigated (TEM). The study was performed within a temperature range of (300 – 500) K. The electrical energy gap and the conductivity of the as-deposited and annealed (373, 473K) Bi<sub>2</sub>Te<sub>2.45</sub>Se<sub>0.55</sub> films were measured. The obtained values are (0.27, 0.26, 0.24 eV) and 3.6×10<sup>3</sup>, 3.7×10<sup>3</sup> and 4.1×10<sup>3</sup> ohm<sup>-1</sup>.cm<sup>-1</sup> respectively. &nbsp;Hall coefficient, the mean free time, the diffusion coefficient of holes, and the diffusion length, charge carrier's concentration, charge carriers' scattering mechanism, and Hall mobility were also examined. The obtained values of the charge carrier's concentration are 2.12×10<sup>17</sup> -2.73×10<sup>17</sup> cm<sup>-3</sup>. The direct and indirect allowed energy gap decreased with increasing annealing temperature. The obtained values of indirect band gap and direct band gap ranges from 0.27- 0.24 eV and 0.375- 0.379 eV, respectively.</p> A.S. Salwa Azza El-Sayed Ahmed Copyright (c) 2022 A.S. Salwa, Azza El-Sayed Ahmed 2022-03-17 2022-03-17 1 58 65 10.26565/2312-4334-2022-1-08 Computation of Structure and Electrical Resistivity of Liquid Na-Rb Alloys https://periodicals.karazin.ua/eejp/article/view/18441 <p>The structure and electrical resistivity of Na<sub>1-x</sub>Rb<sub>x </sub>binary alloys (where x = 0, 0.1, 0.2,…,1) are computed using Percus-Yevick (PY) equation, hard-sphere model and Faber-Ziman formula respectively. The partial structure factors and total structure factor are computed using hard-sphere model for Na<sub>1-x</sub>Rb<sub>x</sub>. In the calculation of resistivity using Faber-Ziman formula, we have employed Ashcroft empty-core pseudo-potential and Hartree dielectric screening. Calculated values of resistivity are compared with the experimental results and other theoretical values reported in literature. It is found that the electrical resistivity calculated using Faber-Ziman formula for binary alloy Na<sub>1-x</sub>Rb<sub>x </sub>is in good agreement with the values reported experimentally.</p> R.R. Koireng P.C. Agarwal Alpana Gokhroo Copyright (c) 2022 R.R. Koireng, P.C. Agarwal, Alpana Gokhroo 2022-03-17 2022-03-17 1 66 69 10.26565/2312-4334-2022-1-09 Enhanced Third Generation Semiconductor Material-Based Solar Cell Efficiency by Piezo-Phototronic Effect https://periodicals.karazin.ua/eejp/article/view/18442 <p>By applying the outward uniform strain on the non-centrosymmetric piezoelectric semiconductor, the polarization charges on the material surface are induced. Polarization charges are often generated within the crystals provided that the applied strain is non-uniform. The strain applied has an effect on electronic transport and can be utilized to modulate the properties of the material. The effect of multiway coupling between piezoelectricity, semiconductor transport properties, and photoexcitation results in piezo-phototronic effects. Recent studies have shown the piezoelectric and semiconductor properties of third-generation semiconductors have been used in photodetectors, LEDs, and nanogenerators. The third-generation piezoelectric semiconductor can be used in high-performance photovoltaic cells. &nbsp;A third-generation piezo-phototronic solar cell material is theoretically explored in this manuscript on the basis of a GaN metal-semiconductor interaction. This study aims to determine the effects of piezoelectric polarization on the electrical performance characteristics of this solar cell material. Performance parameters such as Power Conversion Efficiency, Fill Factors, I-V Characteristics, Open Circuit Voltage, and Maximum Output Power have been evaluated. &nbsp;The piezophototronic effect can enhance the open-circuit current voltage by 5.5 percent with an externally applied strain by 0.9 percent. The study will open a new window for the next generation of high-performance piezo-phototronic effects.</p> Michael Gyan Joseph Parbby Francis E. Botchey Copyright (c) 2022 Michael Gyan, Joseph Parbby, Francis E. Botchey 2022-03-17 2022-03-17 1 70 76 10.26565/2312-4334-2022-1-10 Interactions of Novel Phosphonium Dye with Lipid Bilayers: A Molecular Dynamics Study https://periodicals.karazin.ua/eejp/article/view/18443 <p>In the present work the 100-ns molecular dynamics simulations (MD) were performed in the CHARMM36m force field using the GROMACS package to estimate the bilayer location and mechanisms of the interaction between the novel phosphonium dye TDV and the model lipid membranes composed of the phosphatidylcholine (PC) and its mixtures with cholesterol (Chol) or/and anionic phospholipid cardiolipin (CL). Varying the dye initial position relative to the membrane midplane, the dye relative orientation and the charge state of the TDV molecule it was found that the one charge form of TDV, which was initially translated to a distance of 20 Å from the membrane midplane along the bilayer normal, readily penetrates deeper into the membrane interior and remains within the lipid bilayer during the entire simulation time. It was revealed that the probe partitioning into the model membranes was accompanied by the reorientation of TDV molecule from perpendicular to nearly parallel to the membrane surface. The analysis of the MD simulation results showed that the lipid bilayer partitioning and location of the one charge form of TDV depend on the membrane composition. The dye binds more rapidly to the neat PC bilayer than to CL- and Chol-containing model membranes. It was found that in the neat PC and CL-containing membranes the one charge TDV resides at the level of carbonyl groups of lipids (the distances ~ 1.1 nm, 1.2 nm and 1.3 nm from the bilayer center for the PC, CL10 and CL20 lipid membranes, respectively), whereas in the Chol-containing membranes the probe is located at the level of glycerol moiety (~ 1.5 nm and 1.6 nm for the Chol30 and CL10/Chol30 lipid membranes, respectively). It was demonstrated that the dye partitioning into the lipid bilayer does not affect the membrane structural properties.</p> Olga Zhytniakivska Copyright (c) 2022 Olga Zhytniakivska 2022-03-17 2022-03-17 1 77 84 10.26565/2312-4334-2022-1-11 Using a Scanner to Measure Absorbed Doses with Radiochromic Film Dosimeters https://periodicals.karazin.ua/eejp/article/view/18444 <p>The article provides a sequence of steps for using RISØ calorimeters for calibration and subsequent use of B3 radiochromic film dosimeters (GEX corporation) and a scanner for measuring absorbed doses. Calibration was carried out with the help of electron beam accelerator in the range of absorbed doses of 3 – 40 kGy (measurement range of RISØ calorimeters).<br>In the course of the work, the following was carried out:<br>– calibration of B3 radiochromic dosimetry films using RISØ calorimeters;<br>– plotting a calibration curve for B3 radiochromic dosimetric films;<br>– calculation of approximation functions;<br>– development of a technique for using a flatbed scanner to measure absorbed doses;<br>– estimation of the measurement uncertainties of absorbed doses.<br>Accelerator operation parameters: scanning frequency of the accelerated electron beam – 5 Hz, pulse frequency – 120 Hz, electron energy – 5 MeV, electron beam current – 60 μA. The measurement error of the absorbed dose is 5.8 %.</p> Volodymyr Morgunov Serhii Lytovchenko Volodymyr Chyshkala Natalia Didenko Valentyn Vynnyk Copyright (c) 2022 Volodymyr Morgunov, Serhii Lytovchenko, Volodymyr Chyshkala, Natalia Didenko, Valentyn Vynnyk 2022-03-17 2022-03-17 1 85 95 10.26565/2312-4334-2022-1-12 Fluorescence Study of the Interactions Between Insulin Amyloid Fibrils and Proteins https://periodicals.karazin.ua/eejp/article/view/18445 <p>Self-assembly of proteins and peptides into amyloid fibrils is the subject of intense research due to association of this process with multiple human disorders. Despite considerable progress in understanding the nature of amyloid cytotoxicity, the role of cellular components, in particular proteins, in the cytotoxic action of amyloid aggregates is still poorly investigated. The present study was focused on exploring the fibril-protein interactions between the insulin amyloid fibrils and several proteins differing in their structure and physicochemical properties. To this end, the fluorescence spectral properties of the amyloid-sensitive fluorescent phosphonium dye TDV have been measured in the insulin fibrils (InsF) and their mixtures with serum albumin (SA) in its native solution state, lysozyme (Lz) and insulin (Ins) partially unfolded at low pH. It was found that the binding of TDV to the insulin amyloid fibrils is followed by considerable increase of the fluorescence intensity. In the system (InsF + TDV) the TDV fluorescence spectra were decomposed into three spectral components centered at ~ 572 nm, 608 nm and 649 nm. The addition of SA, Lz or Ins to the mixture (InsF + TDV) resulted in the changes of the fluorescence intensity, the maximum position and relative contributions (<em>f</em><sub>1,3</sub>) of the first and third spectral components into the overall spectra. The Förster resonance energy transfer between the TDV as a donor and a squaraine dye SQ1 as an acceptor was used to gain further insights into the interaction between the insulin amyloid fibrils and proteins. It was found that the presence of SA do not change the FRET efficiency compared with control system (InsF + chromophores), while the addition of Lz and Ins resulted in the FRET efficiency decrease. The changes in the TDV fluorescence response in the protein-fibril systems were attributed to the probe redistribution between the binding sites located at InsF, the non-fibrillized Ins, SA or Lz and protein-protein interface</p> Uliana Tarabara Olga Zhytniakivska Kateryna Vus Valeriya Trusova Galyna Gorbenko Copyright (c) 2022 Uliana Tarabara, Olga Zhytniakivska, Kateryna Vus, Valeriya Trusova, Galyna Gorbenko 2022-03-17 2022-03-17 1 96 104 10.26565/2312-4334-2022-1-13 Investigation of Interaction Mechanisms of High Energy Electrons and Gamma Quantum with Aqueous Solution of Methyl Orange Dye https://periodicals.karazin.ua/eejp/article/view/18446 <p>The level of development of modern nuclear technologies forms a request for the development of new branches of science. At the same time, chemical dosimetry methods are also being improved [1,&nbsp;2]. The essence of such methods consists in the quantitative determination of the radiation-chemical damages to the molecules of a substance when it is exposed to ionizing radiation [3,&nbsp;4]. Liquid and solid solutions of organic dyes have intense bands optical absorption and fluorescence in the visible region of the spectrum, which makes it possible to use them in dosimetry systems [5,&nbsp;6]. The use of organic dyes makes it possible to determine the absorbed dose in the range from 10<sup>-6</sup> to&nbsp;10<sup>4</sup>&nbsp;M&nbsp;Rad [7,&nbsp;8]. In this work, we studied the processes of interaction of gamma-ray and high-energy electron fluxes with an aqueous solution of the organic dye methyl orange (C<sub>14</sub>H<sub>14</sub>N<sub>3</sub>О<sub>3</sub>SNa) [9,&nbsp;10]. The calculations and experiment were carried out on a resonant electron accelerator with energies up to 30&nbsp;MeV. The electron beam energy was 15&nbsp;MeV. A tungsten converter was used to generate gamma quanta. The thickness of the converter varied from 0 to 6&nbsp;mm. We have developed a computer program in C++ to simulate the irradiation process. This program uses the Geant4 class library based on the Monte Carlo method and runs in multi-threaded mode. For calculations, the model “PhysicsList emstandard_opt3” was chosen as the most suitable one. The value of radiation damage per one incident electron and produced gamma-quantum is determined in the work. The simulation results are compared with experimental data. Based on the results obtained, conclusions were drawn about the main mechanisms leading to the decomposition of organic dye molecules, and methods for optimizing the experiment for further research were proposed.</p> Vitaliy V. Tsyats’ko Sergey P. Gokov Yuri G. Kazarinov Tetiana V. Malykhina Copyright (c) 2022 Vitaliy V. Tsyats’ko, Sergey P. Gokov, Yuri G. Kazarinov, Tetiana V. Malykhina 2022-03-17 2022-03-17 1 105 109 10.26565/2312-4334-2022-1-14 Positively Charged Macroparticles in Low-Temperature Plasma https://periodicals.karazin.ua/eejp/article/view/18447 <p>The evolution of a positively charged metallic macroparticle placed into the low-temperature plasma is considered. The influence of the value of the initial macroparticle charge on the dynamics of the electrical potential and temperature of the macroparticle, as well as the possibility of evaporation of a macroparticle due to its interaction with plasma particles are studied. The system of equations of the energy balance and the current balance based on the OML theory, that takes into account the changing of macroparticle potential and its temperature over the time is solved numerically. The solution of the system of equations shows the evolution of the macroparticle potential and temperature within the time interval from the moment when the macroparticle is placed in the plasma until the moment the macroparticle has charged to the floating potential. The positive charge of the macroparticle excludes the thermionic emission and secondary electron emission from the macroparticle surface, as well as the mechanisms of cooling of the macroparticle associated with these emission processes. Analytical expressions that determine the macroparticle potential, the electron current on the macroparticle, as well as the power transferred by plasma electrons in the case when the energy of attraction of electrons to the macroparticle strongly exceeds the energy of thermionic electrons, the energy of secondary electrons and the energy of plasma ions are obtained. A simplified system of equations of the energy balance and the current balance for a positively charged macroparticle is solved; the solution of the simplified equations matches with the solution of the general equations in the region of positive values of the macroparticle potential. Calculations show that during the charging of the macroparticle, its temperature increases up to the boiling point of the macroparticle substance. An equation that determines the conditions under which evaporation of macroparticles is possible has been obtained and solved numerically. The possibility of evaporation of macroparticles of a given size (critical value of the radius) due to initial charging to high positive values of potential is shown. The dependencies of the critical value of the radius on the initial value of the potential for tungsten and copper macroparticles that can be evaporated in a low-temperature plasma are obtained. These solutions bound the region of the parameters where evaporation of a macroparticle is possible and where it is not. The critical values of the potential for copper and tungsten particles with sizes of 0.1 and 1 μm are calculated. The dependence of the radius of a macroparticle on time during the process of vaporization is obtained.</p> Aleksander A. Bizyukov Aleksandr D. Chibisov Dmitry V. Chibisov Oksana A. Zhernovnykova Tamara I. Deуnichenko Nikolai N. Yunakov Copyright (c) 2022 Aleksander A. Bizyukov, Aleksandr D. Chibisov, Dmitry V. Chibisov, Oksana A. Zhernovnykova, Tamara I. Deуnichenko, Nikolai N. Yunakov 2022-03-17 2022-03-17 1 110 115 10.26565/2312-4334-2022-1-15 Resolution of the Ultrasound Doppler System Using Coherent Plane-Wave Compounding Technique https://periodicals.karazin.ua/eejp/article/view/18448 <p>In this work, in the process of plane-wave ultrasound probing from different angles the attainable spatial resolution was estimated on the basis of the previously developed theory of the Doppler response formation. In the theoretical calculations coherent compounding of the Doppler response signals was conducted over the period of changing the steering angles of probing. For this case an analytical expression for the ultrasound system sensitivity function over the field, which corresponds to the point spread function, is obtained. In the case of a rectangular weighting window for the response signals, the resolution is determined by the well-known sinc-function. The magnitude of the lateral resolution is inversely proportional to the range of the steering angles. It is shown that the theoretically estimated magnitude of the Doppler system lateral resolution, when using the technique of coherent plane-wave compounding, is in good agreement with the experimental data presented in literature.</p> Iryna V. Sheina Eugen A. Barannik Copyright (c) 2022 Iryna V. Sheina, Eugen A. Barannik 2022-03-17 2022-03-17 1 116 122 10.26565/2312-4334-2022-1-16