Results 1 - 10 of 68
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[en] An active volume scaling in the bore and length of a Sr atom laser excited in a nanosecond pulse longitudinal He-SrBr2 discharge is carried out. The optimal temperature regime is found for laser oscillation on several different Sr atom and ion lines. The optimal discharge conditions for achieving a maximal multiline average output power are also found. At multiline operation a record average output power of 4.25 W is obtained, more than 90% of which is concentrated on the 6.45 μm Sr atom line. The radial distribution of the laser intensity is obtained experimentally to be a high-beam-quality Gaussian profile.
[en] An investigation of a strontium bromide vapour laser excited by a nanosecond pulsed longitudinal discharge is presented. The optimal discharge conditions for laser oscillation on several Sr atom and ion lines are found. At multiline output an average laser power of 2.4 W is obtained, more than 80% of which is concentrated at the 6.45 μm Sr atom line
[en] Hydride ion conducting electrolytes are used in the electrochemical sensors for detecting hydrogen in liquid sodium coolant of fast reactors. In this connection several combinations of alkali/alkaline earth metal halides mixed with alkali/alkaline earth metal hydrides were investigated for using them as hydride ion conducting electrolytes. Currently, a mixture of CaBr2-CaH2 is used as the solid electrolyte in electrochemical sensors. With a view to develop and understand electrolyte characteristics of CaBr2-SrBr2-CaH2, system, the binary phase diagram of CaBr2-SrBr2 is being investigated in this work. Samples were prepared in dry argon atmosphere glove box using purified CaBr2 and SrBr2 salts covering the composition range of 0 to 100 mol% of CaBr2 in SrBr2 in steps of ∼10 mol%. Approximately 30 mg of samples were loaded inside hermetically closed iron capsules and were analysed by DTA under argon+4% hydrogen gas at controlled heating and cooling rates. Results have shown that the system shows appreciable terminal solid solution at both CaBr2 and SrBr2 rich sides. The system exhibits a eutectic reaction involving the terminal solid solutions at 553℃ and at ∼40 mol% CaBr2 in SrBr2. Further investigations are in progress. (author)
[en] The structure of SrBr2.6H2O has been solved by single-crystal X-ray analysis. Each Sr atom has tricapped trigonal prismatic coordination geometry involving six bridging and three terminal water molecules. The bridging arrangement results in a linear polymeric cation [Sr(H2O)6]2n+n with charges balanced by Br- ions in the lattice. (orig.)
[en] The character of the studied system is determined by the presence of two congruently melting 2KBrxSrBr2 and KBrx2SrBr2 compounds on the K2Br2-SrBr2 side and of solid solutions on the K2Br2-Na2Br2 side. Three nonvariant points: two eutectic points at 452 and 454 deg c and a transition one at 496 deg have been found in the system. The ternary system is divided into three conjugate phase triangles by two triangulating secants
[en] The selection of suitable reaction systems for thermochemical processes, e.g. thermal storage, chemical heat pumps or heat transformers, is challenging. Not only harmlessness of chemicals, theoretical energy storage density and thermodynamics play an important role, but also reversibility, reaction kinetics and cycling stability need to be considered. In this paper a systematic methodology for screening salt hydrates as thermochemical reaction material is suggested and applied to 308 different inorganic salts. It consists of a theoretical analysis of thermodynamic data as well as an extensive experimental analysis of the reversibility, reaction hysteresis and cycling stability. The target application is the heat transformation and reintegration of process waste heat up to 300 °C. SrBr2 meets all requirements for this application and is a promising material.
[en] Highlights: • Local behavior of open thermochemical storage systems using packed bed is studied. • The mass transfer evolution within the reactive bed is carefully investigated. • An asymmetric evolution of the bed permeability have been highlighted during reaction. - Abstract: Their high energy density and low heat losses between storage and recovery times make thermochemical processes a promising way to achieve long-term (seasonal) storage. Among the available reactor configurations, open systems using a packed bed of reactive solid are simple and efficient. This paper reports on the local operation and reactive bed behavior of such systems. Mass transfer changes within the reactive bed, which is the main limitation of such systems, was investigated using several state variables (reaction advancement, pressure drop across the salt bed and bed temperatures). Results from two experimental set-ups were analyzed: a small bench for mass transfer characterization, and a prototype at a larger scale. Both used SrBr_2/H_2O as reactive pair. A salt bed temperature analysis evidenced a reaction front moving within the reactive layer from the moist air inlet to its outlet. A mass transfer study showed marked changes in the reactive bed permeability during the reaction (by one order of magnitude) and with the reactive bed density (from 10"−"9 to 10"−"1"2 m"2 when density range from 300 to 600 kW h m"−"3). During the reaction an asymmetric time course of the bed permeability was also highlighted: as f(X) in dehydration and f(1/X) in hydration.
[en] Differences between transfer coefficients of vegetative and generative plant organs in the soil-plant-system have been found out. No differences were found between strontium nitrate and chloride applied to the useful plants. The discrimination factors show higher values for the nodes in comparison to the leaves of spinach and to the pea pods, i.e. to the aboveground parts of the plant. (author)