Analysis of a Benchmark Experiment on the Hydraulics and Heat Transfer in a Liquid-Metal-Cooled Assembly of Fuel-Element Simulators

A comparative analysis of the experimental data, which were obtained in a benchmark experiment on the thermohydraulics of a model assembly of fuel-element simulators in a flow of sodium-potassium alloy, and calculations performed by specialists, using thermohydraulic codes, from different countries is performed. The model assembly consisted of 25 fuel-element simulators arranged in a square. Russian specialists used the BRS-TVS.R code to perform calculations of the benchmark experiment, Japanese specialists used SPIRAL and AQUA, Spanish specialists used FLUENT, Dutch specialists used STAR-CD, and South Korean specialists used MATRA and CFX. The following experimental and computational parameters were compared: the coolant temperature in the channels under nonuniform geometric and thermal conditions in the assembly, the surface temperature of the measuring fuel-element simulator on the heated section, and the coolant velocity in the assembly cells around the measuring simulator. Special attention was given to investigating the influence of the spacing lattice on the coolant velocity. __________ Translated from Atomnaya Energiya, Vol. 99, No. 5, pp. 336–348, November, 2005.     

On the Possibility of Using Glass Capillaries as Probes of an Atomic-Force Microscope Operating in a Hybrid Mode

Instruments and Experimental Techniques - The possibility of using a glass capillary as a probe of an atomic-force microscope operating in a hybrid mode is demonstrated. Examples of obtaining a...     

Application of the Standard Tapping Mode of an Atomic-Force Microscope for Local Investigations of the Electronic System of Carbon Nanotubes under Vacuum Conditions

Instruments and Experimental Techniques - The possibility of local investigations of the electronic system of carbon nanotubes (CNTs) at a pressure of P < 10–2 mbar is shown using the...     

IR polarizerless gate based on the scattering effect in a nematic liquid crystal

Designs of an IR polarizerless gate based on the electrically controlled light-scattering effect in a liquid crystal are presented. The radiation transmission in the wavelength range of 2.5–25.0 μm has been experimentally measured.     

Temperature dependence of the gain of lasers based on quantum-dot arrays with an inhomogeneously broadened density of states

A model making it possible to describe analytically the temperature dependence of the optical gain and threshold current density in lasers based on quantum-dot arrays characterized by inhomogeneous broadening of the density of states is proposed. At high temperatures the dependence obtained is universal, i.e., it is determined exclusively by the broadening of the density of states, not by its specific form. Fiz. Tekh. Poluprovodn. 33, 1395–1400 (November 1999)     

Carrier heating in quantum wells under optical and current injection of electron-hole pairs

Carrier heating in GaAs/AlGaAs quantum wells (QWs) under optical interband pumping in the spontaneous-emission mode has been studied. The electron temperature was determined as a function of the pumping intensity. The effect of the electric field on the photoluminescence spectrum was examined. The change in the carrier concentration with the drive current in the spontaneous- and stimulated-emission modes in InGaAsSb/InAlGaAsSb QWs was determined from electroluminescence spectra. The rise in the temperature of hot carriers, which results in the increase in the carrier concentration with the drive current, was roughly estimated.     

Optical anisotropy of InAs quantum dots

The optical anisotropy of InAs quantum dots (QDs) synthesized in the regime of either continuous or submonolayer deposition on a singular GaAs(100) surface have been studied using polarized photoluminescence measurements. It is established that an isolated array of QDs formed in a continuous deposition regime possesses a weak (<1–2%) optical anisotropy, whereas the vertical matching (coupling) of such QDs via less than 15-nm-thick spacer layers leads to an 8% linear polarization of PL along the [0$ \bar 1 $ \bar 1 1] crystallographic direction. QDs formed in the regime of submonolayer deposition exhibit a strong (17–20%) anisotropy of emission from the ground and excited states of QDs in the same crystallographic direction.