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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 739 records · Page 41
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Noble gases in Luna 24 core soils

Isotopic abundances of the noble gases have been determined in grain size separates of six soils from different depths in the Luna 24 core. Concentrations of cosmogenic Ne-21 in these soils show a complex pattern as a function of soil depth, and are inconsistent with a single stage, in situ production in a static regolith or with a simple model of slow accumulation of previously unirradiated soils followed by a static period. All soils have apparently had a complex pre-irradiation history. Some soils show significant differences in the concentration of cosmogenic Ne-21 between different grain sizes, which is consistent with suggestions that they formed as a mixture of soils with different maturities. The exact subsurface depth relationships of the soils are not known, and several possibilities are discussed. Because of this factor and the complex nature of the soils, the cosmogenic Ne data do not define the depositional-irradiational history of the core. Luna 24 core soils may have been deposited any time during the past 300 million years.

Bogard, D. D.↗
NASA NTRS1979

Toxicity of pyrolysis gases from polytetrafluoroethylene

A sample of polytetrafluoroethylene was evaluated for toxicity of pyrolysis gases, using various test conditions of the toxicity screening test method developed at the University of San Francisco. Time to death appears to be affected by the material of which the pyrolysis tube is made, with Monel tending to give longer times to death than quartz. When quartz tubes are used, time to death seems to be related to carbon monoxide concentration. When Monel tubes are used, carbon monoxide does not appear to be the principal toxicant.

Hilado, C. J.↗
NASA NTRS1979

Toxicity of pyrolysis gases from polyether sulfone

A sample of polyether sulfone was evaluated for toxicity of pyrolysis gases, using the toxicity screening test method developed at the University of San Francisco. Animal response times were relatively short at pyrolysis temperatures of 600 to 800 C, with death occurring within 6 min. The principal toxicant appeared to be a compound other than carbon monoxide.

Hilado, C. J.↗
NASA NTRS1978

Transport of terrestrial atmospheric gases to the moon

The suprathermal Ion Detector Experiment instruments on the lunar surface have identified fluxes of ions which may be different from the solar wind both in elemental and in isotopic abundances. At present, only O/+/ is (tentatively) identified, but the mechanism operates to produce ions at the moon which have their origin in the earth's atmosphere. Consequently, the 'solar wind' component of the surface-correlated gases is effectively a combination of terrestrial atmospheric ions and the actual solar wind. The results differ from solar wind results if the terrestrial ion abundances strongly differ from those of the solar wind.

Hills, H. K.↗
NASA NTRS1979

Temperature and flow velocity of the interplanetary gases along solar radii

The velocity distributions along solar radii for hydrogen and helium in interplanetary space are calculated by using the Danby-Camm formula modified with a loss function. From these distributions the radial temperature and radial flow velocity of the interplanetary gases are determined. The effects of solar gravitation and ionization loss, due to charge exchange and photoionization, on the gas temperature and velocity are described.

Wu, F. M.↗
NASA NTRS1979

Identification of gaseous SO2 and new upper limits for other gases on Io

The identification of gaseous sulfur dioxide on Io by Voyager 1 is reported, and preliminary upper limits for other atmospheric gases are presented. Averaged spectra taken by the Voyager IRIS experiment in the range of 1,000 to 1,200/cm are interpreted as containing three fundamental sulfur dioxide bands, with intensities most nearly corresponding to an atmospheric model with a sulfur dioxide abundance of 0.2 cm atm. Upper limits for COS, CS2, SO3, H2S, CO2, O3, N2O, H2O, CH4, NH3 and HC1, not detected in the spectra, were calculated on the basis of the radiative transfer equation for temperatures of 130 and 250 K; a depletion of hydrogen, carbon and nitrogen is noted. It is suggested that a SO2 outgassing from a cooling sulfur extrusion is the major source of the observed atmospheric SO2.

Pearl, J.↗
NASA NTRS1979

Isotopic anomalies of noble gases in meteorites and their origins. IV - C3 /Ornans/ carbonaceous chondrites

The C3O chondrites Kainsaz, Lance, and Ornans were studied by an acid dissolution technique to characterize the noble gas components in 3 mineral fractions: HF, HCl-solubles, chromite and carbon, and 'phase Q', a trace mineral containing Ar, Kr, Xe. For all fractions, gas contents decline in the order Kainsaz, Lance, Ornans; this trend parallels volatile contents but not heterogeneity of olivine composition or degree of metamorphism, and reflects progressively higher condensation temperature from the solar nebula. The Ar/Xe ratios and compositions of the three mineral fractions are discussed, and it is concluded that in all primitive chondrites the amount and the chemical separability of CCFXe parallel the abundance of primordial noble gases and other volatiles, such as C, N, Tl, Bi, and In. The close correlation of CCFXe with properties of local origin, such as volatile content and petrologic type, is more consistent with a local than with an extrasolar origin of the component.

Alaerts, L.↗
NASA NTRS1979

Experimental studies of the formation/deposition of sodium sulfate in/from combustion gases

An optical polarization (ellipsometric) technique was developed for measuring rapidly growing and evaporating transparent liquid condensate films (e.g., boric oxide) on solid surfaces exposed to combustion product gases. Results for the B2O3 deposition rate from BCl3-seeded propane/air flames are shown to agree well with the results of earlier interference measurements, and also with theoretical CVD predictions. Evaporation rates (from platinum ribbons into seeded propane air flames) are estimated using the polarization technique. It appears that, compared with the interference method, the polarization technique places less stringent requirements on surface quality, which may justify the added optical components needed for such measurements. It is concluded that the complementary optical methods of polarization (ellipsometry) and interference hold considerable promise for application to the rapid measurement of condensation and evaporation rates in high temperature (e.g., combustion product) environments.

Rosner, D. E.↗
NASA NTRS1980

Investigation of infrared spectra of atmospheric gases to support stratospheric spectroscopic investigations

Spectroscopic instrumentation and the absorption characteristics of atmospheric gases are discussed in relation to the requirements of spectroscopic stratospheric experiments. Improvement in the spectral resolution, accuracy of the line parameters, and the ranges of atmospheric conditions over which information is to be obtained are among the factors considered. Methods of simultaneously analyzing entire bands containing many lines were developed and applied to the analysis of bands of N20 and CO2. Progress in this analysis is reported.

Shaw, J. H.↗
NASA NTRS1980

Isotopic anomalies of noble gases in meteorites and their origins. VI Presolar components in the Murchison C2 chondrite

Rare gases were analyzed by stepped heating in five fractions of a chemically resistant residue from Murchison that had been separated according to grain size and resistance to HClO4. Nine gas components were recognized, of which three appear to be presolar: (1) Ne-E(H) released at 1000-1600 C and located in spinel; (2) Ne-E(L) released at less than 800 C and apparently located in a carbonaceous phase of grain size up to 10 microns; and (3) s-process Xe and Kr released at 1200-1600 C and located in a poorly characterized, possibly carbonaceous phase, distinct from the host phase of Ne-E(L).

Alaerts, L.↗
NASA NTRS1980

Toxicity of pyrolysis gases from foam plastics

Twenty-three samples of flexible foams and twelve samples of rigid foams were evaluated for toxicity of pyrolysis gases, using the USF toxicity screening test method. Polychloroprene among the flexible foams, and polystyrene among the rigid foams, appeared to exhibit the least toxicity under these particular test conditions.

Hilado, C. J.↗
NASA NTRS1979

Solution of Boltzmann equation for highly nonequilibrium diatomic gases rotational translational energy relaxation

The direct simulation Monte Carlo method is applied to solve the Boltzmann equation for collisions between internally excited diatomic gases in highly nonequilibrium states. The semiclassical transition probability is incorporated in the simulation for energy exchange between rotational and translational energy. The results provide details on the fundamental mechanisms of gas kinetics where analytical methods are impractical. The validity of the local Maxwellian assumption and relaxation time, rotational-translational energy transition, and a velocity analysis of the inelastic collision are discussed in detail.

Yoshikawa, K. K.↗
NASA NTRS1980

Resonant tube for measurement of sound absorption in gases at low frequency/pressure ratios

The paper describes a resonant tube for measuring sound absorption in gases, with specific emphasis on the vibrational relaxation peak of N2, over a range of frequency/pressure ratios from 0.1 to 2500 Hz/atm. The experimental background losses measured in argon agree with the theoretical wall losses except at few isolated frequencies. Rigid cavity terminations, external excitation, and a differential technique of background evaluation were used to minimize spurious contributions to the background losses. Room temperature measurements of sound absorption in binary mixtures of N2-CO2 in which both components are excitable resulted in the maximum frequency/pressure ratio in Hz/atm of 0.063 + 123m for the N2 vibrational relaxation peak, where m is mole percent of added CO2; the maximum ratio for the CO2 peak was 34,500 268m where m is mole percent of added N2.

Zuckerwar, A. J.↗
NASA NTRS1980

Real-gas effects 1: Simulation of ideal gas flow by cryogenic nitrogen and other selected gases

The thermodynamic properties of nitrogen gas do not thermodynamically approximate an ideal, diatomic gas at cryogenic temperatures. Choice of a suitable equation of state to model its behavior is discussed and the equation of Beattie and Bridgeman is selected as best meeting the needs for cryogenic wind tunnel use. The real gas behavior of nitrogen gas is compared to an ideal, diatomic gas for the following flow processes: isentropic expansion; normal shocks; boundary layers; and shock wave boundary layer interactions. The only differences in predicted pressure ratio between nitrogen and an ideal gas that may limit the minimum operating temperatures of transonic cryogenic wind tunnels seem to occur at total pressures approaching 9atmospheres and total temperatures 10 K below the corresponding saturation temperature, where the differences approach 1 percent for both isentropic expansions and normal shocks. Several alternative cryogenic test gases - air, helium, and hydrogen - are also analyzed. Differences in air from an ideal, diatomic gas are similar in magnitude to those of nitrogen. Differences for helium and hydrogen are over an order of magnitude greater than those for nitrogen or air. Helium and hydrogen do not approximate the compressible flow of an ideal, diatomic gas.

Hall, R. M.↗
NASA NTRS1981

Effect of type of explosives and physical-mechanical properties of explosive rock on formation of toxic gases in atmosphere of shafts

The quality of toxic gases formed during explosive work in underground shafts depends upon the type of explosives and the conditions of explosion. Several types of explosives and rocks were examined. All remaining conditions were maintained the same (sandy-argillaceous stemming, electrical method of explosions, diameter of blast holes, and the direct triggering of charges).

Mindeli, E. O.↗
NASA NTRS1981

Simulation of ideal-gas flow by nitrogen and other selected gases at cryogenic temperatures

The real gas behavior of nitrogen, the gas normally used in transonic cryogenic tunnels, is reported for the following flow processes: isentropic expansion, normal shocks, boundary layers, and interactions between shock waves and boundary layers. The only difference in predicted pressure ratio between nitrogen and an ideal gas which may limit the minimum operating temperature of transonic cryogenic wind tunnels occur at total pressures approaching 9 atm and total temperatures 10 K below the corresponding saturation temperature. These pressure differences approach 1 percent for both isentropic expansions and normal shocks. Alternative cryogenic test gases were also analyzed. Differences between air and an ideal diatomic gas are similar in magnitude to those for nitrogen and should present no difficulty. However, differences for helium and hydrogen are over an order of magnitude greater than those for nitrogen or air. It is concluded that helium and cryogenic hydrogen would not approximate the compressible flow of an ideal diatomic gas.

Hall, R. M.↗
NASA NTRS1980

Photofragmentation-laser induced fluorescence - A new method for detecting atmospheric trace gases

A new method for the in situ detection of nonfluorescing molecular species is proposed: photofragmentation-laser induced fluorescence (PF-LIF). In this approach, the species to be detected is first laser photolyzed at a wavelength lambda (1), producing one or more vibrationally excited photofragments. Before vibrational relaxation occurs, one of these photofragments is pumped into a bonding excited state by a second laser pulse centered at wavelength lambda (2). Fluorescence is sampled at a wavelength lambda (3), where lambda (3) is less then lambda (2) and lambda (1). This pumping configuration thus permits massive discrimination against Rayleigh and Raman scattering as well as white noise fluorescence from the laser wavelengths lambda (1) and lambda (2). The technique should be both highly sensitive and selective for numerous atmospheric trace gases. Specific sampling schemes for detecting NO2, NO3, and HNO2 are proposed. Various noise sources and chemical interferences are discussed. Specific calculations that estimate the sensitivity of the PF-LIF system for detecting NO2, NO3, and HNO2 are given.

Rodgers, M. O.↗