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[en] Complete text of publication follows. In the previous research of cryogenic complex (dusty) plasma we observed experimentally the possibility of the formation of dust structures in cryogenic environment at 4.2-77 K. It was revealed from the experiments, among others, that the dust structures with high concentration of dust particles can be formed, in which interparticle distance is comparable with particle size - so-called superdense dusty plasma structures. Such structures had exotic properties such as globular (spherical) form, free boundaries, etc. In the present work new results on the experimental investigations of spheroidizing - phenomenon of the transition of dust structures to compact globular shape at cryogenic temperatures - were presented. The experiments were made by means of recently developed techniques and new cryogenic facilities (optical helium cryostat). Possible nature of such phenomenon is discussed.
[en] Acoustic properties of alloys of Ge-Pb system have been studied. The temperature dependencies of ultrasound propagation velocity in alloys of Ge-Pb system were investigated in detail. It has been defined that the melting temperature of germanium is 1211 K and lead - 600 K. Based on conducted studies it has been shown that ultrasound propagation velocity depending on temperature decreases linearly.
[en] The low-cycle fatigue phenomenon in the framework of plastic deformation is studied considering the temperature parameter. The experimental results obtained for the plastic strain Δεp (1-7%), in the temperature range 20-300 o C are examined. The conclusion is that the lifetime, expressed by the number of stress cycles, Nf, is given by the relation Nf = C exp(-A/T)(Δεp)β+αΔT, where T is the absolute temperature, Δεp is double of plastic deformation amplitude, and C, A, β, and α are material constants. This relation can be interpreted as being the generalization of a relation, known in literature as the 'Coffin-Manson relation', but which does not include the temperature parameter. The validation of this relation can be done either on the results presented in this paper or an those published in literature. (Author)
[en] The high temperature leak before break (LBB) approach is supposed to be applied to the design of KALIMER-600. While the assessment of a crack instability is a essential element for an LBB application, solid methods for evaluation of a crack instability at high temperature condition are yet to be established even though it is well provided for in a PWR application. In this study, US BS7910, UK R5/R6, and French RCC-MR A16 were examined and a tentative procedure was presented for an LBB application to sodium cooled fast reactor KALIMER- 600
[en] Electrical transfer from a room temperature power source to a superconducting system is done via conventional or superconducting current leads and superconducting buses or links. The principles of optimization of these devices are presented, with emphasis on the cryogenic, electrical, and superconductor related aspects that drive choices for a system
[en] This work is primarily concerned with the calculation of the properties of solids at elevated temperatures or high pressures, using both atomistic and ab initio simulations. Chapter three describes a method to calculate the free energy and its analytic derivatives, with respect to all the external and internal degrees of freedom, using lattice statics and lattice dynamics in the quasi-harmonic approximation, of lattices which are periodic in only two dimensions. Derivatives are calculated by means of first-order perturbation theory and detailed expressions for all the lattice sums, including long range forces, are presented. The method is used to calculate the temperature variation of the surface free energy, surface structure, and vibrational density of states of some representative oxide surfaces. In chapters four and five we study the thermodynamics, mechanism, and kinetics of the B1-B2 phase transition in alkali halides and alkaline-earth oxides. Both the Buerger and Watanabe-Tokonami-Morimoto mechanisms are shown to have similar activation energies. Transition pathways show marked variations with pressure and can be used to rationalize the pressure hysteresis observed experimentally. Simple kinetic models are used to establish reaction rates for this transition. We also show that, in contrast to the suggestion of Hofmeister [AMH97], the bulk modulus of NaCl is found to increase during this transition. We question the use, at high pressures, of semiempirical relations between infra-red frequencies and KT, based on a model which includes only nearest-neighbour short-range interactions. For the alkali halides, the limiting value of the Grueneisen parameter in the limit T→0 shows a stronger variation with cation than anion radius. In chapter five, for a wide range of halides, we calculate the pressure derivative of c44, c12 and c11 from a pair potential model and, for the first time, Hartree-Fock theory. We conclude that this dependence is due largely to the variation of this pressure derivative of the shear stiffness, c44. In the final chapter we outline an approach, based on the Vinet 'universal' equations of state [VSFR97], to calculate the Helmholtz energy of systems, for the prediction of the characteristics of an explosive, in both solid and liquid phase, from a minimal input data set. (author)
[en] In a very high temperature reactor (VHTR), thermal oxidation of graphite components is inevitable due to oxidants impurities from a graphite outgassing and a leakage in a heat exchanger. The mechanical properties of graphite are severely degraded by oxidation, the oxidation of graphite has been widely studied to analyze the safety of the reactors and assess the operational life of core structures. The major concern of the safety concept of the VHTR is the limitation of the maximum fuel temperature even in the case of hypothetical accidents to about 1600 .deg. C. However, in most cases, the former oxidation researches were performed in the normal operation temperature of the VHTR below 900 .deg. C. In this study, we examined the effect of temperature on oxidation rates of candidate nuclear grade graphites for VHTR using a thermogravimeter
[en] Complete text of publication follows. In this work the quantum pseudopotential for pair interaction of particles was considered, which takes into account the diffraction effects due to the uncertainty principle and the coupling between symmetry and diffraction effects in two-component plasma (the region of temperatures 104K < T < 108K and densities 1021 cm-3 < n ≤ 1024 cm-3). Numerically the exact values of the Slater sum based on the method which was presented in work  were calculated. Interpolation formula for the pseudopotential which takes into account the effect of diffraction and many particle quantum effects and is based on the exact numerical values of the Slater sum was founded. The interpolation formula at condition ∞→T has the following form: Φ/T→∞ = eαeβ / r (1 - exp[-r/λαβ]), that corresponds to the Deutsch potential. For higher densities the pseudopotential which does not depend on density was considered. The results are in good agreement with similar data in , but diverge from data of the ion-electron pair's interaction given in . This fact is explained by the different choices of the wave function. In works [5-7] quantum effects which effective potential takes into account were considered.