Application of quasi-steady-state plasma streams for simulation of ITER transient heat loads

The paper presents experimental investigation of energy characteristics of the plasma streams generated with quasi—steady—state plasma accelerator QSPA Kh-50 and adjustment of plasma paramenters from the point of view its applicability for simulation of transient plasma heat loads expected for ITER disruptions and type I ELMs. Possibility of generation of high-power magnetized plasma streams with ion impact energy up to 0.6 keV, pulse length 0.25 ms and heat loads varied in wide range from 0.5 to 30 MJ/m² has been demonstrated and some features of plasma interaction with tungsten targets in dependence on plasma heat loads are discussed.     

In-line and following-up tests of perspective fusion-reactor materials in plasma focus devices

The paper presents results of recent experiments, as performed with the PF-1000 and PF-6 Plasma-Focus facilities, which were aimed at investigation of the correlation between processes of the irradiation of different materials of fusion devices and results of this irradiation. Among the irradiated samples there were pure tungsten, tantalum, copper, aluminum, and alloys, based on these metals, various steels, carbon and carbon-based materials, which are designed for plasma facing components or constructional parts of future thermonuclear reactors of the inertial- and magnetic-confinement types. The corpuscular radiation consisted of high-energy (E _D>100 keV) deuterium ion beams and fast (v _str ≥ 10⁷ cm/s) deuterium-plasma streams. They were investigated by a number of methods with spatial and temporal resolution. Particular attention was paid to the verification of diagnostic techniques, which might be used for time- and space-resolved studies of the interaction process. Correlation of these data with information obtained from subsequent analytical investigation of some of the irradiated specimens, as performed by means of a number of methods typical for material sciences, gives possibility to deduce physical mechanisms of the deuterium implantation and radiation damage of the investigated materials in dependence on the conditions of their irradiation.     

Specific features of the crystal and local structures of compounds formed in the Dy<Subscript>2</Subscript>O<Subscript>3</Subscript>–HfO<Subscript>2</Subscript> system

The crystal and local structures of compounds formed in the Dy₂O₃–HfO₂ system (at molar ratios from 1: 3 to 3: 1) in the course of isothermal annealing of X-ray amorphous mixed hydroxides at temperatures up to 1600°C have been studied. At the molar ratio Dy₂O₃: HfO₂ from 1: 3 to 1: 1, crystallization leads to formation of single-phase defect fluorite solid solutions nDy₂O₃ ? mHfO₂ with clearly pronounced nonequivalence of parameters of local environment of Dy³⁺ and Hf⁴⁺ cations. It has been found that Dy₂H₂O₇ (Dy₂O₃: HfO₂ = 1: 2) samples have a tendency to pyrochlore-type ordering in both the cationic and anionic sublattices.     

The effect of synthesis conditions on the structure of compounds formed in the Dy<Subscript>2</Subscript>O<Subscript>3</Subscript>–TiO<Subscript>2</Subscript> system

Crystallization and phase transition processes taking place in the Dy₂O₃–TiO₂ system during the isothermal annealing of the precursors synthesized by co-precipitation were studied. The phase composition of the obtained powders is determined by not only the chemical composition of the precursor (Dy₂O₃: TiO₂ ratio) and annealing temperature but also by the procedure of precursor synthesis determining the uniformity of Dy and Ti distribution in the precursor precipitate. Higher homogeneity of precursor particles provides the formation of almost single-phase nanocrystaline dysprosium titanate (Dy₂TiO₅, Dy₂Ti₂O₇) powders at annealing temperatures of 800–1000°C.     

Effect of the introduction procedure and concentration of yttrium cations on the crystal structure of (1–<Emphasis Type="Italic">x</Emphasis>)ZrO<Subscript>2</Subscript> · <Emphasis Type="Italic">x</Emphasis>Y<Subscript>2</Subscript>O<Subscript>3</Subscript> powders

An integrated study of the crystal and local structures of complex oxides (1–x)ZrO₂ · xY₂O₃ (x = 0.005–0.18, YSZ), precipitated from solutions of metal salts and annealed in air, was carried out. For the use of deposition from solutions, reverse co-precipitation was found to be the method of choice for introducing yttrium cations into YSZ, ensuring the maximum stabilization effect of high-temperature phases. An increase in the yttrium content induces polymorphic transformations, monoclinic phase (P21/a) → tetragonal phase (P4₂/nmc) (for x = 0.02) → cubic phase (Fm\(\bar 3\)m) (for x = 0.08), in the samples prepared at temperatures of ≤1000°C. A Raman study of the local structure of YSZ powders confirmed the formation of a single-phase tetragonal structure for the 2YSZ and 3YSZ samples and identified trace amounts of the tetragonal phase for the 8YSZ and 18YSZ samples with the cubic structure.     

Molecular design of macrocyclic extractants for extraction and separation of alkali and alkaline-earth metals

The distribution coefficients of the alkaline and alkali-earth metal nitrates are determined for the processes of extraction from nitric acid solutions with crown ethers, which differ in sizes of their cycles (from 18 to 22 atoms) and in side phenyl and cyclohexyl substituents, but have unchanged number of the O atoms in a cycle. The phenyl and cyclohexyl derivatives of 18-crown-6 are found to be more efficient extractants of alkali metals as compared with unsubstituted crown ethers. However, the selectivity of separation of a pair Cs-Na remains low. The 18-crown-6 derivatives with one and two cyclohexyl fragments selectively extract Sr, which can be used to separate it from the remaining alkali and alkaline-earth metals. An increase in the size of a macrocycle from 18 to 20 and 22 atoms leads to a reduction in the extraction efficiency for all alkali and alkaline-earth metals, insignificantly improves separation of a pair Cs-Na, but noticeably deteriorates Sr-Na separation.     

IR Photodetectors Based on Isoperiodic Epitaxial Layers of Lead Tin Chalcogenides

Technical Physics - IR photodetectors have been made on Pb/δ-layer/p-Pb1 –xSnxTe1 –ySey/p+-Pb0.8Sn0.2Te/Au and Au/δ-layer/n-Pb1 –xSnxTe1 –ySey(BaF2)/Pb...