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At least 775 records · Page 43
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on PrH18(BrO6)3 by Materials Project

Pr(H2O)9(BrO3)3 crystallizes in the hexagonal P6_3mc space group. The structure is zero-dimensional and consists of six hypobromous acid;dihydrate molecules and two Pr(H2O)9 clusters. In each Pr(H2O)9 cluster, Pr3+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Pr–O bond distances ranging from 2.51–2.55 Å. There are three inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a water-like geometry to one Pr3+ and two equivalent H1+ atoms. In the second O2- site, O2- is bonded in a water-like geometry to one Pr3+ and two equivalent H1+ atoms. In the third O2- site, O2- is bonded in a water-like geometry to one Pr3+ and two equivalent H1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Li3H24Ru(ClO2)6 by Materials Project

(Li(H2O)4)3RuCl6 is Tungsten Carbide-like structured and crystallizes in the monoclinic C2/c space group. The structure is zero-dimensional and consists of four ruthenium(6+) hexachloride molecules and four Li(H2O)4 clusters. In each Li(H2O)4 cluster, there are two inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded to six O2- atoms to form face-sharing LiO6 octahedra. There are a spread of Li–O bond distances ranging from 2.16–2.19 Å. In the second Li1+ site, Li1+ is bonded to six O2- atoms to form face-sharing LiO6 octahedra. There are two shorter (2.14 Å) and four longer (2.16 Å) Li–O bond lengths. There are twelve inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the ninth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the tenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the eleventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the twelfth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted water-like geometry to one Li1+ and two H1+ atoms. In the second O2- site, O2- is bonded in a distorted water-like geometry to one Li1+ and two H1+ atoms. In the third O2- site, O2- is bonded in a distorted water-like geometry to one Li1+ and two H1+ atoms. In the fourth O2- site, O2- is bonded in a distorted water-like geometry to two Li1+ and two H1+ atoms. In the fifth O2- site, O2- is bonded in a distorted water-like geometry to two Li1+ and two H1+ atoms. In the sixth O2- site, O2- is bonded in a distorted water-like geometry to two Li1+ and two H1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BiH18C3S3(O2F)9 by Materials Project

Bi(H2O)9(CF3)3(SO3)3 crystallizes in the hexagonal P6_3/m space group. The structure is zero-dimensional and consists of six fluoroform molecules, six sulfur trioxide molecules, and two Bi(H2O)9 clusters. In each Bi(H2O)9 cluster, Bi5+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are six shorter (2.49 Å) and three longer (2.61 Å) Bi–O bond lengths. There are three inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a water-like geometry to one Bi5+ and two H1+ atoms. In the second O2- site, O2- is bonded in a water-like geometry to one Bi5+ and two equivalent H1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na2V9MoH35(N2O19)2 by Materials Project

(Na(H2O)5)2V9MoO28(NH4)3NH3 crystallizes in the triclinic P1 space group. The structure is zero-dimensional and consists of one ammonia molecule, three ammonium molecules, one Na(H2O)5 cluster, and one V9MoO28 cluster. In the Na(H2O)5 cluster, there are two inequivalent Na sites. In the first Na site, Na is bonded to six O atoms to form edge-sharing NaO6 octahedra. There are a spread of Na–O bond distances ranging from 2.36–2.53 Å. In the second Na site, Na is bonded to six O atoms to form edge-sharing NaO6 octahedra. There are a spread of Na–O bond distances ranging from 2.40–2.48 Å. There are twenty inequivalent H sites. In the first H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the second H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the third H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the fourth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the fifth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the sixth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the seventh H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the eighth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the ninth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the tenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the eleventh H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the twelfth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the thirteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the fourteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the fifteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the sixteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the seventeenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the eighteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the nineteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the twentieth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. There are ten inequivalent O sites. In the first O site, O is bonded in a distorted water-like geometry to one Na and two H atoms. In the second O site, O is bonded in a distorted water-like geometry to two Na and two H atoms. In the third O site, O is bonded in a distorted water-like geometry to one Na and two H atoms. In the fourth O site, O is bonded in a distorted water-like geometry to one Na and two H atoms. In the fifth O site, O is bonded in a distorted water-like geometry to one Na and two H atoms. In the sixth O site, O is bonded in a distorted water-like geometry to one Na and two H atoms. In the seventh O site, O is bonded in a distorted water-like geometry to one Na and two H atoms. In the eighth O site, O is bonded in a distorted water-like geometry to one Na and two H atoms. In the ninth O site, O is bonded in a distorted water-like geometry to two Na and two H atoms. In the tenth O site, O is bonded in a distorted water-like geometry to one Na and two H atoms. In the V9MoO28 cluster, there are nine inequivalent V sites. In the first V site, V is bonded in a 6-coordinate geometry to six O atoms. There are a spread of V–O bond distances ranging from 1.63–2.32 Å. In the second V site, V is bonded in a 6-coordinate geometry to six O atoms. There are a spread of V–O bond distances ranging from 1.67–2.25 Å. In the third V site, V is bonded in a 6-coordinate geometry to six O atoms. There are a spread of V–O bond distances ranging from 1.62–2.42 Å. In the fourth V site, V is bonded in a 6-coordinate geometry to six O atoms. There are a spread of V–O bond distances ranging from 1.64–2.38 Å. In the fifth V site, V is bonded to six O atoms to form distorted edge-sharing VO6 octahedra. There are a spread of V–O bond distances ranging from 1.73–2.12 Å. In the sixth V site, V is bonded to six O atoms to form distorted edge-sharing VO6 octahedra. There are a spread of V–O bond distances ranging from 1.73–2.12 Å. In the seventh V site, V is bonded in a 6-coordinate geometry to six O atoms. There are a spread of V–O bond distances ranging from 1.65–2.34 Å. In the eighth V site, V is bonded in a 6-coordinate geometry to six O atoms. There are a spread of V–O bond distances ranging from 1.61–2.47 Å. In the ninth V site, V is bonded in a 6-coordinate geometry to six O atoms. There are a spread of V–O bond distances ranging from 1.66–2.31 Å. Mo is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Mo–O bond distances ranging from 1.74–2.33 Å. There are twenty-eight inequivalent O sites. In the first O site, O is bonded in a bent 120 degrees geometry to two V atoms. In the second O site, O is bonded in a single-bond geometry to one V atom. In the third O site, O is bonded to six V atoms to form distorted edge-sharing OV6 octahedra. In the fourth O site, O is bonded in a single-bond geometry to one V atom. In the fifth O site, O is bonded in a bent 120 degrees geometry to two V atoms. In the sixth O site, O is bonded in a bent 120 degrees geometry to two V atoms. In the seventh O site, O is bonded in a trigonal non-coplanar geometry to two V and one Mo atom. In the eighth O site, O is bonded in a trigonal non-coplanar geometry to three V atoms. In the ninth O site, O is bonded in a bent 120 degrees geometry to two V atoms. In the tenth O site, O is bonded in a bent 120 degrees geometry to two V atoms. In the eleventh O site, O is bonded in a single-bond geometry to one V atom. In the twelfth O site, O is bonded in a water-like geometry to two V atoms. In the thirteenth O site, O is bonded in a bent 120 degrees geometry to two V atoms. In the fourteenth O site, O is bonded in a single-bond geometry to one V atom. In the fifteenth O site, O is bonded in a single-bond geometry to one V atom. In the sixteenth O site, O is bonded in a bent 120 degrees geometry to two V atoms. In the seventeenth O site, O is bonded in a bent 120 degrees geometry to two V atoms. In the eighteenth O site, O is bonded in a single-bond geometry to one V atom. In the nineteenth O site, O is bonded in a bent 120 degrees geometry to two V atoms. In the twentieth O site, O is bonded in a bent 120 degrees geometry to one V and one Mo atom. In the twenty-first O site, O is bonded in a trigonal non-coplanar geometry to two V and one Mo atom. In the twenty-second O site, O is bonded in a trigonal non-coplanar geometry to three V atoms. In the twenty-third O site, O is bonded in a bent 120 degrees geometry to two V atoms. In the twenty-fourth O site, O is bonded in a bent 120 degrees geometry to two V atoms. In the twenty-fifth O site, O is bonded in a single-bond geometry to one Mo atom. In the twenty-sixth O site, O is bonded to five V and one Mo atom to form edge-sharing OV5Mo octahedra. In the twenty-seventh O site, O is bonded in a single-bond geometry to one V atom. In the twenty-eighth O site, O is bonded in a bent 120 degrees geometry to one V and one Mo atom.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Oxygen diffusion in garnet: Experimental calibration and implications for timescales of metamorphic processes and retention of primary O isotopic signatures

Knowledge of oxygen diffusion in garnet is crucial for a correct interpretation of oxygen isotope signatures in natural samples. A series of experiments was undertaken to determine the diffusivity of oxygen in garnet, which remains poorly constrained. The first suite included high-pressure (HP), nominally dry experiments performed in piston-cylinder apparatus at: (1) T = 1050–1600 °C and P = 1.5 GPa and (2) T = 1500 °C and P = 2.5 GPa using yttrium aluminum garnet (YAG; Y3Al5O12) cubes. Second, HP H2O-saturated experiments were conducted at T = 900 °C and P = 1.0–1.5 GPa, wherein YAG crystals were packed into a YAG + Corundum powder, along with 18O-enriched H2O. Third, 1 atm experiments with YAG cubes were performed in a gas-mixing furnace at T = 1500–1600 °C under Ar flux. Finally, an experiment at T = 900 °C and P = 1.0 GPa was done using a pyrope cube embedded into pyrope powder and 18O-enriched H2O. Experiments using grossular were not successful. Profiles of 18O/(18O+16O) in the experimental charges were analyzed with three different secondary ion mass spectrometers (SIMS): sensitive high-resolution ion microprobe (SHRIMP II and SI), CAMECA IMS-1280, and NanoSIMS. Considering only the measured length of 18O diffusion profiles, similar results were obtained for YAG and pyrope annealed at 900 °C, suggesting limited effects of chemical composition on oxygen diffusivity. However, in both garnet types, several profiles deviate from the error function geometry, suggesting that the behavior of O in garnet cannot be fully described as simple concentration-independent diffusion, certainly in YAG and likely in natural pyrope as well. The experimental results are better described by invoking O diffusion via two distinct pathways with an inter-site reaction allowing O to move between these pathways. Modeling this process yields two diffusion coefficients (D values) for O, one of which is approximately two orders of magnitude higher than the other. Taken together, Arrhenius relationships are:logDm2s-1=-7.2(±1.3)+(-321(±32)kJmol-12.303RT) for the slow pathway, andlogDm2s-1=-5.4(±0.7)+(-321(±20)kJmol-12.303RT) for the fast pathway. We interpret the two pathways as representing diffusion following vacancy and inter-stitial mechanisms, respectively. Regardless, our new data suggest that the slow mechanism is prevalent in garnet with natural compositions, and thus is likely to control the retentivity of oxygen isotopic signatures in natural samples. The diffusivity of oxygen is similar to Fe-Mn diffusivity in garnet at 1000–1100 °C and Ca diffusivity at 850 °C. However, the activation energy for O diffusion is larger, leading to lower diffusivities at P-T conditions characterizing crustal metamorphism. Therefore, original O isotopic signatures can be retained in garnets showing major element zoning partially re-equilibrated by diffusion, with the uncertainty caveat of extrapolating the experimental data to lower temperature conditions.

Geochemistry & Geophysics↗
DOE OSTI2022

Carbon Dioxide Flux Measurement System (CO2FLX) Instrument Handbook

The Southern Great Plains (SGP) carbon dioxide flux (CO2 flux) measurement systems provide half-hour average fluxes of CO2, H2O (latent heat), and sensible heat. The fluxes are obtained by the eddy covariance technique, which computes the flux as the mean product of the vertical wind component with CO2 and H2O densities, or estimated virtual temperature. A three-dimensional sonic anemometer is used to obtain the orthogonal wind components and the virtual (sonic) temperature. An infrared gas analyzer is used to obtain the CO2 and H2O densities. A separate sub-system also collects half-hour average measures of meteorological and soil variables from separate 4-m towers.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Computationally Guided Design of Multiple Impurities Tolerant Electrode (Final Report)

The current project was based on a combined experimental and computational approach, which can help recommend better cathode materials under multiple impurities conditions. The PI will mainly take in charge of experimental and computational thermodynamics of the selected cathode materials for the SOFC applications under multiple impurities. While the co-PI will run the electrochemical tests of the cathodes recommended and eventually the long-term degradation tests. At the end of the project, a multiple tolerant cathode material based on the combined experimental and computational approach will be recommended and the reliability of the commonly used accelerated testing will be evaluated. It will address multiple impurities poisoning effect of SO2, CO2, Cr and H2O on the LSM, LSCF and LNO cathodes by identifying the formation of the detrimental secondary phases by XRD, SEM and TEM techniques. And further recommended cathode material will be subjected to electrochemical testing and the most promising ones will be applied to long-term tests. The hybrid approach the PI proposed will not only be applied to the design of multiple impurities tolerant cathodes but will also be considered in the future oxygen electrode applications in SOECs or reversible SOCs. This hybrid computational and experimental approach includes four sections: 1) Investigation of single impurity poisoning on LSM, LSCF and LNO cathodes in the presence of SO2, CO2, Cr. In this section, LSM, LSCF cathodes from FuelCellMaterials and LNO cathodes from Sol-Gel synthesis will be heat-treated in the above single impurity. And the formation of the secondary phases as well as the corresponding simulations will be cross compared, which shows good agreement between each other. Meanwhile, the accelerated testing approach will be evaluated in these systems compared with the previous published work to understand the reliability of the approach. 2) Investigation of multiple impurities poisoning on LSM, LSCF and LNO cathodes in the presence of Cr+H2O, SO2+Cr and SO2+Cr+H2O conditions. We have also applied these 3 candidate cathodes under these multiple impurities’ conditions and the long-term degradation mechanism of the multiple impurities will be understood with the help of the combined experimental and computational approach. Meanwhile, the synergistic effect of those impurities will be compared with the individual ones in the same cathode system to further reveal the actual operating conditions. 3) Electrochemical testing and polarization of the recommended cathode. We have demonstrated very low polarization resistance in LSCF (core)-LSM (shell) electrodes using MSD process and analyzed impedance spectra using DRT analysis and confirming that the low polarization resistance in LSM infiltrated MSD cells is due to reduction in polarization resistance associated with O2-adsorption process. 4). Long-term degradation testing. We have developed a versatile MSD-based process to deposit various continuous coatings onto porous scaffolds and established baseline for longer term Cr-impurity testing in future projects.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Impact of Hydrogen Combustion on the Oxidation-induced Degradation of Heavy-duty Diesel Engine Piston Materials

High temperature ferritic-martensitic steels are candidate materials for heavy-duty diesel engine pistons. The envisioned transition to hydrogen blended fuels is expected to alter the post-combustion atmosphere in the engines, primarily resulting in a higher water vapor content (> 20 vol%) and potentially higher exhaust gas temperatures. The oxidation resistance of existing and newly developed alloys will be a critical life-limiting mechanism under these conditions. In the present work, the oxidation behavior of candidate piston alloys was evaluated in air+10 vol.% H2O and air+30 vol.% H2O at 700°C. Thermal cyclic (1h cycle) exposures were conducted for two variants of commercial UNSS42200 ferritic-martensitic steel and two developmental alloy steels for up to 300h. The developmental alloys each have similar compositions but with one containing elevated Cu levels of 3 wt.%, A significant reduction in resistance to breakaway oxidation was observed for the commercial alloys in the higher water vapor atmosphere. Microstructural characterization (optical metallography, scanning electron microscopy and electron microprobe analysis) revealed the formation of thick Fe-rich oxides even for the high Cr (~12 wt.%) steels after an initial stage of protective oxidation with MnCr-rich spinels. The impact of the evaporation-induced loss of Cr on the time and temperature dependent compositional changes in the alloys was correlated with experimental findings. For the developmental alloys, Cu additions appear to play a role in significantly reducing oxidation kinetics in air+30 vol.% H2O at 700°C.

Pillai, Rishi [ORNL] (ORCID:0000000243688197)↗
DOE OSTI2025

CO2 Profiling System for CO2 Storage (a1-level)

The Southern Great Plains (SGP) carbon dioxide flux (CO2FLUX) measurement systems provide half-hour average fluxes of CO2, H2O (latent heat), sensible heat, and momentum. The systems use the eddy covariance technique, which computes the fluxes from the vertical wind speed in combination with the concentrations of CO2 and H2O, temperature, and horizontal wind speed, respectively. A 3D sonic anemometer obtains the wind components and the temperature, while an infrared gas analyzer measures CO2 and H2O. A sub-system also measures half-hour averages of radiation, meteorological, and soil measurements.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2026

Expert Elicitation for Tidal Energy Levelized Cost of Energy: Present and Future

In accordance with the Government Performance and Results Act (GPRA), H2O annually assesses marine energy technology development resulting from government-funded research and development programs and strategy. For GPRA reporting, H2O uses the levelized cost of energy (LCOE) - which represents the total system cost per unit of energy produced - to measure the progression of marine energy technology development, assess the impact of their research and development programs, and identify future research priorities. To support H2O's GPRA reporting requirements and inform future strategy, the National Laboratory of the Rockies conducted a tidal energy LCOE expert elicitation study to estimate present and future LCOE[AB2.1]. This report describes the motivation and background for the elicitation study, the methodology used to conduct the study, and the study results. It also provides future recommendations for accelerated tidal energy LCOE reduction based on feedback from study participants.

16 TIDAL AND WAVE POWER↗
NASA NTRS1971

AE mass spectrometer antechamber study

The formation of CO2 and H2O in a gold plated antechamber was investigated when a beam of oxygen is introduced. It was found that at room temperature the formation of CO2 and H2O is negligibly small. However, at the top temperature (197 C) which could be achieved with the existing system, both products were formed in significant quantities. Desorption of CO2 and H2O at this temperature is still slow and incomplete which accounts for the delayed response to the beam conditions. Although the catalytic reactions take place already with molecular oxygen, the reactions are significantly enhanced if the oxygen beam is partially dissociated.

Herzog, R. F.↗
NASA NTRS1971

Performance of a 10 mlb biowaste resistojet.

Description of the thrusting performance of a 10-mlb thrust, concentric-tubes biowaste resistojet, which was life tested on hydrogen and ammonia propellants for 8000 hours. Thrusting performance is presented for H2, H2O, CH4, and CO2 as well as typical biopropellant mixtures CO2-CH4, H2O-CH4 and CO2-H2O. Using Pt-Ir alloy heater tubes, 235 and 575 seconds were obtained for water and hydrogen propellants. Overall total power efficiencies were 66%, which includes losses for a preevaporator close-coupled for the water tests. Vibration to 1.0 sq q/Hz with an overall G rms of 36, shock at 30 g's and acceleration to 8 g's simulating a launch were passed by the thrustor.

Phillips, D. G.↗
NASA NTRS1971

Studies of positive-ion composition in the equatorial D-region ionosphere.

Evaluation of two daytime D-region positive-ion composition measurements performed at Thumba, India, for solar zenith angles of 53.2 and 27.8 deg. Comparison of upleg ram with downleg wake data shows a large increase in the concentration of heavy ions 48(+), NO(+) . H2O; 55(+), H3O(+) . (H2O)2; and M(+) greater than 65(+) for the downleg reduced shock condition. Peak concentrations of 48(+) and 55(+) occur at unit optical depth for Lyman alpha radiation. The ion 37(+), H3O(+) . H2O, is dominant for chi = 27.8 deg, but not for chi = 53.2 deg, consistent above 80 km with an origin from the X-ray production of O2(+). Laboratory measurements have shown that the ion, NO(+), can be transferred to heavy hydrates 48(+), 55(+), and M(+) greater than 65(+) by a reaction chain starting with NO(+) + X + M = NO(+) . X + M, where X can be O2, N2, CO2 or a combination of all three, depending on the rate of reaction. This chain, together with a similar reaction scheme starting with O2(+) and ending in 19(+), 37(+), and heavier clusters, is used to provide a consistent explanation for the hydrated ions observed in the D region.

Goldberg, R. A.↗
NASA NTRS1972

Composition of the upper clouds of Venus.

Recent developments have shed new light on the composition of the upper Venus clouds. An analysis of the Mariner 5 occultation data has led to improved temperature and pressure profiles. When these are combined with transit data, it is concluded that there is an optically thin cloud layer with a top at 81-km altitude where the temperature and pressure are, respectively, 175 K and 3 mb. The inclusion of temperatures derived from the near-infrared CO2 bands leads to the postulate of a second cloud deck with a top at 61-km altitude, where temperature and pressure are 260 K and 240 mb. Additional important constraints on cloud models are imposed by the measured abundances of HCl and H2O, by the polarization data, and by the reflection and emission spectra. It is concluded that the leading candidate for the uppermost clouds is liquid drops of HCl-H2O, that there is no recommended candidate for the second cloud deck, and that H2O ice is at most a minor component of these cloud systems.

Rea, D. G.↗
NASA NTRS1973

Nuclear characteristics of a fissioning uranium plasma test reactor with light-water cooling

An analytical study was performed to determine a design configuration for a cavity test reactor. Test section criteria were that an average flux of 10 to the 15th power neutrons/sq cm/sec (E less than or equal to 0.12 eV) be supplied to a 61-cm-diameter spherical cavity at 200-atm pressure. Design objectives were to minimize required driver power, to use existing fuel-element technology, and to obtain fuel-element life of 10 to 100 full-power hours. Parameter calculations were made on moderator region size and material, driver fuel arrangement, control system, and structure in order to determine a feasible configuration. Although not optimized, a configuration was selected which would meet design criteria. The driver fuel region was a cylindrical annular region, one element thick, of 33 MTR-type H2O-cooled elements (Al-U fuel plate configuration), each 101 cm long. The region between the spherical test cavity and the cylindrical driver fuel region was Be (10 vol. % H2O coolant) with a midplane dimension of 8 cm. Exterior to the driver fuel, the 25-cm-thick cylindrical and axial reflectors were also Be with 10 vol. % H2O coolant. The entire reactor was contained in a 10-cm-thick steel pressure vessel, and the 200-atm cavity pressure was equalized throughout the driver reactor. Fuel-element life was 50 hr at the required driver power of 200 MW. Reactor control would be achieved with rotating poison drums located in the cylindrical reflector region. A control range of about 18 percent delta k/k was required for reactor operation.

Whitmarsh, C. L., Jr.↗
NASA NTRS1973

Liquid carbon dioxide and the Martian polar laminae

One of the most important findings of the Mariner 9 mission was the existence of a set of apparent stacked layers in both the north and south polar regions of Mars. The total thickness of the laminated terrain is approximately several kilometers. Because the Martian atmosphere is composed largely of CO2 and because the frost point of CO2 is known to be reached in both polar regions, it has been assumed that the volatiles in the bright laminae are in appreciable part condensed CO2, although condensed H2O, and a CO2-H2O clathrate are also possible. As long as the ratio of CO2 to H2O is large, the physical properties will be dominated by the CO2.

Sagan, C.↗
NASA NTRS1974

Effect of pollutant gases on ozone production by simulated solar radiation

The present investigation provides some information related to the problem of ozone destruction by nitric oxide emission from high flying vehicles. It is found that CO and H2O can counteract NO destruction of O3 in laboratory simulations. The addition of CO and H2O to aircraft exhausts could be a practical means of reducing the damage of the UV-filtering ozone layer. It is also discovered that NO is not regenerated as it destroys ozone, except at low stratospheric pressures. It is believed that the presence of H2O and CO gives rise to a series of reactions which provide a kinetically competitive pathway for the NO, causing it to go into NO2 production via these substrates rather than via O3.

Wong, E. L.↗