•Below 630 °C etching proceeds via periodic 2D vacancy island nucleation.•In 630–830 °C interval the onset of step flow triggers surface excavation.•Above 830 °C the etching proceeds by step ...flow.•Activation energy of the Si(1 1 1) surface etching by Se beam is 2.65 eV.
Using in situ ultrahigh vacuum reflection electron microscopy, we have first visualized the evolution of step-bunched Si(1 1 1) surface during Se beam etching depending on substrate temperature T and terrace size required for survival of etching-induced vacancies. Below T ~ 630 °C, the etching proceeds in layer-by-layer mode via periodic nucleation of small 2D vacancy islands without noticeable motion of steps. However, in 630–830 °C interval, the etching of the 7 × 7 reconstructed Si(1 1 1) step-bunched surface is realized by both step flow and continuous nucleation and growth of 2D vacancy islands on wide terraces, which leads to the excavation of initially flat surface between step bunches. At T > 830 °C, the etching proceeds by step flow with preservation of initial surface morphology. We have found that the Si(1 1 1) surface etching by Se beam is characterized by 2.65 eV activation energy that limits etching kinetics in low-temperature range when the whole Si(1 1 1) surface is converted to disordered impurity-induced Si(1 1 1)“1 × 1”-Se phase.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
2.
Airborne Conical Antenna Arrays Ponomarev, L. I.; Vasin, A. A.; Terekhin, O. V. ...
Journal of communications technology & electronics,
10/2020, Volume:
65, Issue:
10
Journal Article
Peer reviewed
The study presents an algorithm and the results of analysis of the sum-and-difference directional characteristics of an airborne conical antenna arrays (AAs) of slot radiators located on the ...conductive surface of the cone. It is shown that the maximum directivity of such antennas in the radiation mode and the steepness of the difference radiation pattern (in the
E
-plane) in the receive mode for pointed cones can significantly exceed similar parameters of the equivalent planar aperture.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The current status of the nuclear problems of the thermonuclear fusion research program and, in particular, tritium, is discussed. It is noted that thermonuclear power generation without a uranium or ...thorium blanket is problematic; the key nuclear problems of the fusion–fission hybrid system remain unsolved. It is proposed that an integrated strategic analysis be made of the thermonuclear research program and the realistic possibilities of its application in nuclear power-engineering.
Different approaches to the transmutation of Np, Am, and Cm in molten-salt reactors are compared: based on the eutectics LiF–NaF–KF (BZhSR), LiF–NaF–BeF
2
(MOSART), and the salt LiF–BeF
2
(ZhSR-S). ...In addition the efficiency of transmutation in a BREST-1200 type fast reactor is evaluated. It is shown that the highest possible transmutation efficiency can be realized in a reactor based on the salt LiF–NaF–KF (~306 kg/yr per 1 GW(t)). The results show that further study of the physical and chemical properties of LiF–NaF–KF is warranted, specifically, a study of the solubility of a fuel composition with fission products and an investigation of the possibility of developing a reactor with a fast neutron spectrum on the basis of this salt.
The paper presents an analysis of the bacterial purification effectiveness by UV radiation of wastewater in modern industrial aquaculture recirculation systems. the effectiveness of water ...purification in the ultrasound system by a set of filters for mechanical treatment and ultraviolet radiation is experimentally established. UV lamp allows to process water with rays that effectively destroy the organic matter formed in it. Pathogenic and conditionally pathogenic genera, such as: Aeromonas, Pseudomonas, Staphylococcus, Vibrio, Enterobacteria were differentiated.
The requirements for the characteristics of phased antenna arrays of radar systems designed to probe the Earth’s surface from an aircraft are determined. The design features of an onboard ...pass-through phased array antenna with a monopulse irradiator are considered. The results of the calculation of the directivity characteristics and the magnitude of the gain coefficient losses of the phase-controlled antenna array are presented.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The idea on a homogeneous nuclear reactor, first suggested by Ya B Zeldovich and Yu B Khariton in 1939, has since had its ups and downs and is now re-emerging, enriched with the knowledge and ...experience accumulated over the years having past. One of the current versions of the idea, the fast molten-salt reactor with a U-Pu fuel cycle, is presented in this paper.
The issues of Np, Am, Cm recycling in a BZhSR molten-salt reactor with a fast neutron spectrum based on LiF–NaF–KF eutectic are examined. The results of a comparative analysis of the efficacy of ...transmutation for different BZhSR fuel compositions and core volume are reported. It is shown that BZhSR with an initial load of enriched uranium and Np, Am, Cm fl uorides makes it possible to transmute ~1 ton/yr Np, Am, Cm on average over 50 years of operation at 1650 MW(t). The advantage of the chosen arrangement is the capability of Np, Am, Cm replenishment without adding additional enriched uranium even after the first run with duration 300 EFPD.
The results of recent studies of the structural morphological transformations of Si(111) and Si(100) surfaces using in situ ultrahigh-vacuum reflection electron microscopy (UHV REM) are presented. It ...is established that high-temperature sublimation from extremely wide Si(111) terraces occurs at a smaller activation energy (3.77 eV) than from the vicinal surface (4.04 eV). A nonmonotonic change in the kinetics of step bunching during a smooth transition from sublimation to growth on the Si(100) surface is recorded. The structural transformations caused by electromigration of positively charged Sn adatoms on the reconstructed Si(111) surface are demonstrated. It is shown that Si(111) surface etching under exposure to a Se molecular beam occurs in a layer-by-layer mode due to the desorption of SiSe
2
molecules with activation energy of 2.65 eV.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
An algorithm of direction finding of a set of arbitrarily correlated multipath harmonic and quasiharmonic signals in the presence of a normal white noise is substantiated. Results of numerical ...simulation for different variants of correlation between signals arriving at the input of a circular antenna array are presented. It is shown that, in order to increase the accuracy of determination of directions of arrival, number, and amplitudes of the arriving signals with the use of the proposed algorithm, it is expedient to perform preliminary fast Fourier transform procedure with subsequent direction finding at each frequency component.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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