VANADIUM-BASED ALLOYS FOR FUSION ENERGETICS

A.I. Kondrik, G.P. Kovtun

Full Text :   (1560 kB, Rus.) 

Abstract
The review of technical articles devoted to main achievements in the field of production technology and properties investigation of vanadium-based prospective materials for thermonuclear power was carried out. The low-activation alloys V-(4-5)%Cr-(4-5)%Ti was taken into special consideration in the terms of possibility of probable application in the first wall/blanket of prospective commercial fusion reactors (FR). The influence of impurities content on induced activity after use in FR with possibility of further recycling has been studied. The stress-strain properties of V-Cr-Ti alloys are described. The basic factors impacting on low- and high-temperature limits of V-Cr-Ti operating temperature range are investigated. The achievements in understanding of microstructure evolution are stated. The successes in production of alternative alloys with improved microstructure were considered, and the issues originated during the development of the reference alloy V-4Cr-4Ti were explored. The ways of the further improvement of vanadium-based alloys are pointed.

KEY WORDS: vanadium alloys, structural materials, induced activity, stress-strain properties, creep, microstructure.

NUCLEAR-PHYSICAL METALLOGRAPHY OF ZIRCONIUM ALLOYS

V.G. Kirichenko, A.I. Kirdin

Full Text :   (4150 kB, Rus.) 

Abstract
Тhe principles of nuclear-physical metallurgy of zirconium alloys by using nuclear gamma resonance (Mossbauer effect) were considered. The results of nuclear-physical investigations of hyperfine interactions and phase transformations in zirconium alloys under complex thermomechanical treatment, irradiation and corrosion were described. The results of physical metallurgy simulation of nuclear transmutation effects in zirconium alloys were stated. The microstructure of simulated transmutation effects ternary alloys differs from microstructure of source alloys and it is determine by crystallization modes of binary and ternary zirconium alloys. The ensembles of intermetallic particles formed after thermal and mechanical treatment with final isochronous ageing in temperature range from 570 К to 1070 К are characterized by different connection type with zirconium matrix and increased intermetallic phases concentration in surface layers with depth up to 0,3μm. The obtained concentration-isomer shift-quadrupole splitting 3D-diagram and isomer shift dependences on quadrupole splitting enabled experimental data correct handling and surely identify the phases in crystalline and amorphous zirconium alloys. High mobility of phase intermetallic particles in zirconium matrix are revealed. Zirconium alloys corrosion in high parameters water leads to formation of heterogeneous phase oxide films contained iron in oxide amorphous phases and in intermetallic phases. Admixture electron structure in zirconium effect on structure and phase transformations appears as transference of charge and electron density during intermetallic phases forming and as correlation of segregation factor, corrosion stability and admixture implantation energy dependences on Miedema's electronegativity.

KEY WORDS: nuclear-physical methods, hyperfine interactions, Mossbauer effect, zirconium, alloying, surface, electron structure, irradiation, corrosion.

BRITTLE SUBSURFACE DESTRUCTION OF SOLID UNDER BOMBARDMENT OF LOW-ENERGY IONS

A.I. Kalinichenko, V.E. Strel'nitskij

Full Text :   (520 kB, Rus.) 

Abstract
Thermoelastic stresses arising due to interaction of low-energy ion with solid are theoretically investigated. Characteristics of the thermal source generating the elastic pulse are determined in the model of nonlocal thermoelastic peak of the ion. The possibility of use of linear thermoacoustics equations for determination of generated pulse amplitude is analysed. Spatial-temporal characteristics of the stress field near flat free surface of the target are determined. The originating stress value is compared with the dynamic ultimate strength of the target material to determine possibility of the brittle subsurface destruction of the target. Necessary and sufficient conditions of the cluster sputtering in the framework of proposed mechanism are formulated. The range of the depths of location of thermoelastic peak providing separation and ejection of the material from the target surface as well as size and shape of the ejected fragment are determined. Dependences of the sputtering coefficient N on species and energy of the ion and on material characteristics are studied. The value of N is esteemed for the case of the low-energy Fe⁺ ion in the target of amorphous iron.

KEY WORDS: ion bombardment, thermal spike, thermoelastic stress, brittle fracture, cluster sputtering.

PHYSICAL BACKGROUND AND MODELING OF FACILITY CONSTRUCTION FOR TRANSMUTATION OF SOME ELEMENTS OF RADIOACTIVE WASTE USING THERMONUCLEAR NEUTRONS

Y.V. Rudychev, R.P. Slabospitskij, M.A. Khazhmuradov

Full Text :   (1100 kB, Rus.) 

Abstract
Two variants of radioactive waste transmutation systems using of thermonuclear neutrons are considered. In first one the transuranium elements and the fission products are irradiated together, in second one they are irradiated separately. Advantages and disadvantages of these variants are analyzed. Both systems are simulated. Efficiency of each variant of radioactive waste transmutation is analyzed. Physical background of radioactive waste transmutation by thermonuclear neutrons is arranged.

KEY WORDS: spent fuel, radioactive waste, transmutation, simulation, Monte-Carlo method.

USE OF THE ACTIVE WELL COINCIDENCE COUNTER FOR THE SEMICONDUCTOR NEUTRON DETECTOR DEVELOPMENT

D.V. Kutniy, V.E. Kutniy, N.P. Odeychuk, V.E. Tovkanetz, A.V. Rybka, A.A. Zakharchenko

Full Text :   (1100 kB, Rus.) 

Abstract
The opportunity of neutron registration from isotopic source ²⁴¹AmLi by solid state semiconductor detector based on high purity germanium and Cd-converter was reviewed. The measurement of gamma background of isotopic neutron source ²⁴¹AmLi in the range 200…800 keV was conducted. The main gamma-ray lines with an intensity ≥ 2 × 10^-6 % were identified. It was founded that the appearance of prompt gamma-rays 558.6 and 651.3 keV was a result of neutrons and Cd-converter interaction. Efficiency of neutrons registration by coaxial germanium detector ? 50,5 × 42,5 mm was estimated.

KEY WORDS: neutron, detector, gamma-irradiation, ²⁴¹AmLi, converter, Cd, nuclear reactor, efficiency of registration.

GAMMA ACTIVATION AND SPECTRAL ANALYSIS OF ELEMENT COMPOSITION, STRUCTURE AND SORPTION ACTIVITY OF RADIATION SYNTHESIZED MAGNETITE NANOPARTICLES

N.P. Dikiy, A.N. Dovbnya, E.P. Medvedeva, N.P. Khlapova, I.D. Fedorets, V.L. Uvarov, Yu.V. Lyashko

Full Text :   (380 kB, Rus.) 

Abstract
Solutions of ferrum sulphate and osmium tetroxide have been irradiated with bremssrahlung radiation from the electron accelerator in NSC KIPT. The elemental composition of the synthesized nanoparticles of magnetite and Os has been studied with gamma-activation approach. The morphology, particle dimensions and particle size distributions, crystal lattice state, optical and sorbtion properties of the synthesized nanomaterials were studied with the electron microscopy, with UV- Vis and IR-spectroscopy and with hemiluminiscent analysis. It was demonstrated that the synthesized magnetite particles can be used as an magnetic-driven sorbent to pathogenic microorganisms.

KEY WORDS: nanoparticles of magnetite and osmium, electron accelerator, gamma activation analisis, optical density, IR - spectroscopy, biochemiluminescence.

INFLUENCE OF DEAD TIME ON INACCURACY AT MEASUREMENT OF CHARACTERISTICS OF IONIZING RADIATIONS

S.A. Dushkin, V.A. Odinets, A.N. Orobinskiy

Full Text :   (240 kB, Rus.) 

Abstract
Extended and non-extended models of dead time are described; errors due to the influence of dead time when measuring characteristics of ionizing radiation are given; the upper border of the range and the error of measuring the characteristic are determined taking into account the influence of dead time; the dependence of the time of measuring characteristic on the error when measuring dead time is determined taking into the upper border of the range and the measurement error.

KEY WORDS: dead time, extended model, non-extended model, measurement range, measurement error.

THE DIFFERENCE BETWEEN FREQUENCY OF PARAMETRIC X-RAY RADIATION AND BRAGG FREQUENCY

A.V. Shchagin

Full Text :   (500 kB, Rus.) 

Abstract
The analytical expression for the difference between classic frequency of parametric X-ray radiation (PXR) and Bragg frequency at the same observation direction is obtained for kinematical case. The behavior of the difference is analyzed at angular distance and in the vicinity of the PXR reflection, related formulae are derived. It is shown that Bragg frequency always exceeds the PXR frequency. The difference of frequencies increases proportionally to square of the angular distance from the reflection center in the vicinity of the PXR reflection center. The difference of the frequencies in the field of the reflection where the PXR yield has maximum value exceeds one in the reflection center by factor two. Methods of experimental research of X-rays with two close frequencies are discussed.

KEY WORDS: parametric X-ray radiation, frequency of parametric X-ray radiation, crystal, Bragg frequency, difference of X-ray frequencies.

NORMAL MODE OF RF DISCHARGE IN AMMONIA

V.A. Lisovskiy

Full Text :   (470 kB, Rus.) 

Abstract
This paper reports the current-voltage characteristics of a weak-current mode of the RF discharge in ammonia for the RF electric field frequencies of 13.56 MHz and 27.12 MHz. The only abnormal mode of burning is found to be observed at low pressure i.e. the current growth is accompanied by the RF voltage increase with a complete coverage of the electrode area by the discharge. The normal mode occurs at higher gas pressure i.e. the current growth takes place on increasing the area occupied by the discharge on the electrodes. The discharge burns in the abnormal mode after the electrode surface is completely covered with the discharge. The normal current density is found to increase with the growth of gas pressure and RF field frequency. An analytical model is reported predicting that the normal current density is proportional to the pressure to 5/6 power and to the frequency to 11/6 power furnishing the satisfactory description of the experimental results.

KEY WORDS: radio frequency capacitive discharge, weak-current mode, normal mode, abnormal mode, current-voltage characteristic, ammonia.

EXPERIMENTAL INVESTIGATION OF THE RF DISCHARGES RADIAL STRUCTURE

V.A. Lisovskiy, N.D. Kharchenko, V.D. Yegorenkov

Full Text :   (490 kB, Rus.) 

Abstract
This paper studies the distribution of the glow intensity of the discharge plasma against the tube radius and reports the radial profiles of electron temperature and plasma concentration in the RF discharge registered with a Langmuir probe. An abrupt increase of electron temperature and glow intensity near the tube wall in the weak-current α-mode of the RF discharge is revealed, the radial distribution of plasma concentration possessing a maximum near the radial sheath boundary. In the γ-mode of the RF discharge the electron temperature decrease in the total plasma volume leads to an ambipolar electric field weakening and the peak of the glow intensity near the tube wall vanishes.

KEY WORDS: radio-frequency capacitively coupled discharges, radial structure, α-mode of the RF discharge, γ-mode of the RF discharge, low pressure, nitrogen.

INCOHERENT TRANSPORT AND PSEUDOGAR IN Нo₁Ba₂Cu₃O_7-δ SINGLE CRYSTALS WITH A DIFFERENT OXYGEN CONTENT

R.V. Vovk, M.A. Obolenskii, A.A. Zavgorodny, A.M. Corsunskiy

Full Text :   (320 kB, Ukr.) 

Abstract
The temperature dependences of transversal electro-resistance of Нo₁Ba₂Cu₃O_7-δ single crystals with different oxygen content have been investigated. It is shown that in the case of the connection Нo₁Ba₂Cu₃O_7-δ, unlike Y₁Ba₂Cu₃O_7-δ, at the increase of deficit of oxygen there is strengthening of processes of localization of carriers, which is accompanied by transition from the PG-mode to the mode of conductivity with variable length hopping.

KEY WORDS: HTSC, pseudogap, Нo₁Ba₂Cu₃O_7-δ single crystals, incoherent transport, transversal conductivity, localization of carriers.

PSEUDOGAP STATE IN SLIGHTLY DOPED BY ALUMINIUM YBACUO SINGLE CRYSTALS WITH A GIVEN TOPOLOGY OF PLANE DEFECTS

I.L. Gulatis, M.A. Obolenskii, R.V. Vovk, A.A. Zavgorodniy, K.A. Kotvitskaya

Full Text :   (330 kB, Ukr.) 

Abstract
In present work the temperature dependence of the ab-plane conductivity of YBa₂Cu_3-yAl_yO_7-δ single crystals with the system of the unidirectional twin boundaries was investigated. The excess conductivity for the analyzed single crystals, within a wide temperature interval T_f < Т < T*, is described by exponential temperature dependence. The temperature dependence of pseudogap is satisfactorily described within the BCSh-BEK crossover theoretical model.

KEY WORDS: excess conductivity, doping, YВaCuO single crystals, high temperature superconductivity, crossover, pseudogap state.

X-RAY STUDIES OF MICROSTRUCTURE AND TEXTURE OF ZIRCONIUM AFTER LARGE PLASTIC DEFORMATION AT 100 K AND 300 K

V.I. Sokolenko, I.F. Borisova, I.N. Butenko, E.V. Karasjova, D.G. Malykhin, A.V. Matz

Full Text :   (220 kB, Rus.) 

Abstract
The microstructure of zirconium samples deformed by rolling on 92 % at 300 K and 100 K and annealed at 750 and 800 K is studied by modified approximation method with double-Voigt methodology of analyses of physical X-ray lines half-width. The studies show the identity of all microstructure characteristics between deformed and also between annealed samples without of dependence of working temperature. At this it is note an increasing crystallographic texture for low-temperature deformed zirconium. It is concluded that structure changes in zirconium concerned to influence of working temperature becomes from middle structure scale and above that is confirmed by another studies.

KEY WORDS: X-ray analyses, zirconium, microscopic structure, texture, method of approximation, half-width, microstrains, particles size, creep.

DISCOVERY OF THE SHUBNIKOV PHASE (TYPE II SUPERCONDUCTORS)

V.V. Slezov, I.I. Papirov, A.G. Shepelev

Full Text :   (2100 kB, Rus.) 

Abstract
A nonsimple path of type II superconductor discovery, which was covered by the International scientific community over 7 years, is considered in some detail. The impact of this discovery, made in 1935/1936 by the outstanding physicist L.V. Shubnikov and his co-workers at the Ukrainian Physical-Technical Institute (former name of NSC KIPT), on present-day physics and engineering is demonstrated.

KEY WORDS: superconductivity, electrical properties, magnetic properties, type II superconductors, magnetic systems.