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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,225 records · Page 68
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Structural and optical properties of electron beam evaporated yttria stabilized zirconia thin films

Yttria stabilized zirconia (10 mole % Y{sub 2}O{sub 3}) thin films were deposited on quartz substrates using electron beam physical vapor deposition at the substrate temperatures in the range 300 – 973 K. XRD analysis showed cubic crystalline phase of YSZ films with preferred orientation along (111). The surface roughness was found to increase with the increase of deposition temperatures. The optical band gap of ∼5.7 eV was calculated from transmittance curves. The variation in the optical properties is correlated with the changes in the microstructural features of the films prepared as a function of substrate temperature.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Detection of Cu{sub 2}Zn{sub 5}SnSe{sub 8} and Cu{sub 2}Zn{sub 6}SnSe{sub 9} phases in co-evaporated Cu{sub 2}ZnSnSe{sub 4} thin-films

Cu{sub 2}ZnSnSe{sub 4} thin-films for photovoltaic applications are investigated using combined atom probe tomography and ab initio density functional theory. The atom probe studies reveal nano-sized grains of Cu{sub 2}Zn{sub 5}SnSe{sub 8} and Cu{sub 2}Zn{sub 6}SnSe{sub 9} composition, which cannot be assigned to any known phase reported in the literature. Both phases are considered to be metastable, as density functional theory calculations yield positive energy differences with respect to the decomposition into Cu{sub 2}ZnSnSe{sub 4} and ZnSe. Among the conceivable crystal structures for both phases, a distorted zinc-blende structure shows the lowest energy, which is a few tens of meV below the energy of a wurtzite structure. A band gap of 1.1 eV is calculated for both the Cu{sub 2}Zn{sub 5}SnSe{sub 8} and Cu{sub 2}Zn{sub 6}SnSe{sub 9} phases. Possible effects of these phases on solar cell performance are discussed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

The use of processes evaporation and condensation to provide a suitable operating environment of systems

All electronic components which exhibit electrical conductor resistance, generates heat when electricity is passed (Joule - Lenz’s Law). The generated heat is necessary to take into surrounding environment. To reduce the operating temperature of electronic components are used various types of cooling in electronic devices. The released heat is removed from the outside of the device in several ways, either alone or in combination. Intensification of cooling electronic components is in the use of heat transfer through phase changes. From the structural point of view it is important to create a cooling system which would be able to drain the waste heat converter for each mode of operation device. Another important criterion is the reliability of the cooling, and it is appropriate to choose cooling system, which would not contain moving elements. In this article, the issue tackled by the phase change in the heat pipe.

42 ENGINEERING↗
DOE OSTI2018

Analysis of antifoam agent degradation products in an evaporator

A wetting agent used to control foaming in the Chemical Processing Cell at the Defense Waste Processing Facility degrades to form compounds that could volatilize to form vapor exceeding the lower flammability limit. Three identified components of concern were hexamethyl disiloxane, trimethyl silanol, and propanal. Analytical methods were developed and implemented on a real waste sample to monitor degradation products. In this work, using standards, an extraction method with dichloromethane and analysis by gas chromatography-mass spectrometry and hydrogen nuclear magnetic resonance was developed. Both methods had detection limits less than 1 mg/L for the analytes.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Effects of radiation pressure on the evaporative wind of HD 209458b

ABSTRACT The role of radiation pressure in shaping exoplanet photoevaporation remains a topic of contention. Radiation pressure from the exoplanet’s host star has been proposed as a mechanism to drive the escaping atmosphere into a ‘cometary’ tail and explain the high velocities observed in systems where mass-loss is occurring. In this paper, we present results from high-resolution 3D hydrodynamic simulations of a planet similar to HD 209458b. We self-consistently launch a wind flowing outwards from the planet by calculating the ionization and heating resulting from incident high-energy radiation, and account for radiation pressure. We first present a simplified calculation, setting a limit on the Lyman-α flux required to drive the photoevaporated planetary material to larger radii and line-of-sight velocities. We then present the results of our simulations, which confirm the limits determined by our analytic calculation. We thus demonstrate that, within the limits of our hydrodynamic simulation and for the Lyman-α fluxes expected for HD 209458, radiation pressure is unlikely to significantly affect photoevaporative winds or to explain the high velocities at which wind material is observed, though further possibilities remain to be investigated.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

Effects of charge exchange on the evaporative wind of HD 209458b

ABSTRACT The role of charge exchange in shaping exoplanet photoevaporation remains a topic of contention. Exchange of electrons between stellar wind protons from the exoplanet’s host star and neutral hydrogen from the planet’s wind has been proposed as a mechanism to create ‘energetic neutral atoms’ (ENAs), which could explain the high absorption line velocities observed in systems where mass-loss is occurring. In this paper, we present results from three-dimensional hydrodynamic simulations of the mass-loss of a planet similar to HD 209458b. We self-consistently launch a planetary wind by calculating the ionization and heating resulting from incident high-energy radiation, inject a stellar wind into the simulation, and allow electron exchange between the stellar and planetary winds. We predict the potential production of ENAs by the wind–wind interaction analytically, and then present the results of our simulations, which confirm the analytic limits. Within the limits of our hydrodynamic simulation, we find that charge exchange with the stellar wind properties examined here is unable to explain the absorption observed at high Doppler velocities.

79 ASTRONOMY AND ASTROPHYSICS↗