Density measurements of trace gases
Nondispersive infrared absorption analyzer measures radiation absorption of specific gases. Apparatus uses feedback nulling to measure weak signals.
Dimeff, J.↗
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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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The relation between isotopic composition of argon and carbon in natural gases
The methods and results of determination of the argon and carbon isotope compositions of hydrocarbon gases of Mezozoic complexes of Western Siberia are presented. Based on the Ar-36, Ar-40, C-12, C-13 content of the various deposits and on the presumed mechanisms of entry of these isotopes into the deposits, it is concluded that formation of natural gas in some deposits included vertical migration from a lower complex.
Gavrilov, Y. Y.↗
Scaled equation of state parameters for gases in the critical region
In the light of recent theoretical developments, the paper presents an accurate characterization of anomalous thermodynamic behavior of xenon, helium 4, helium 3, carbon dioxide, steam and oxygen in the critical region. This behavior is associated with long range fluctuations in the system and the physical properties depend primarily on a single variable, namely, the correlation length. A description of the thermodynamic behavior of fluids in terms of scaling laws is formulated, and the two successfully used scaled equations of state (NBS equation and Linear Model parametric equation) are compared. Methods for fitting both equations to experimental equation of state data are developed and formulated, and the optimum fit for each of the two scaled equations of the above gases are presented and the results are compared. By extending the experimental data for the above one-component fluids to partially miscible binary liquids, superfluid liquid helium, ferromagnets and solids exhibiting order-disorder transitions, the principle of universality is concluded. Finally by using this principle, the critical regions for nine additional fluids are described.
Sengers, J. M. H. L.↗
Atmospheric rare gases in lunar rock 60015
Aliquots of lunar rock 60015 were subjected to various types of exposure and handling designed to produce terrestrial contamination, in order to test the possibility of a terrestrial origin for the terrestrial-like trapped Xe reported for lunar rock samples. Crushing the rock produced up to order-of-magnitude increases in the abundances of Ar, Kr, and Xe relative to the millimeter-sized chips of 60015 previously analyzed. Contrary to expectations for atmospheric contamination, high temperatures (above 1000 C) were necessary to remove about 75% of the trapped Kr and Xe, and the rare-gas elemental abundance ratios differed from those in terrestrial samples believed to have occluded atmospheric gases. It is concluded, on the basis of similar temperature-release profiles and elemental-fractionation patterns, that the trapped Xe observed in all these 60015 analyses is atmospheric contamination. Such a conclusion cannot unequivocally be drawn for other lunar rocks containing terrestrial-like Xe, but the present results demonstrate that arguments based on high extraction temperatures and elemental abundance ratios cannot be useful to rule out rare-gas atmospheric contamination in such samples.
Niemeyer, S.↗
Carbonaceous chondritic xenoliths and planetary-type noble gases in gas-rich meteorites
The source of the planetary-type noble gases in gas-rich meteorites is identified as finely divided (submillimeter to millimeter-sized), widely dispersed carbonaceous chondritic fragments. Trace-element abundances, noble-gas elemental abundances and isotopic abundances of xenon are compatible with the hypothesis that the carbonaceous chondritic carrier is present in amounts of a few percent in the gas-bearing portions of gas-rich chondrites and achondrites.
Wilkening, L. L.↗
Release of radiogenic gases from the moon
The rate of escape of Ar-40 from the moon is calculated from mass-spectrometer data obtained at the Apollo-17 landing site. It is shown that the rate of loss of Ar from the moon varies significantly over periods the order of one lunation and that the average loss rate is about 3 t/a, corresponding to about 6% of the present rate of Ar production by K decay within the moon. These features of the Ar loss-rate data are interpreted as evidence that this gas originates in the partially molten asthenosphere, which in turn requires that early differentiation only affected the outer 600 to 1,000 km of the moon, trapping significant amounts of radioactive materials in the present asthenosphere. The relationship between the venting of Ar and other radiogenic gases in the lunar atmosphere is discussed.
Hodges, R. R., Jr.↗
Removal of contaminant gases from an electrolytic urine pretreatment process
The effluent gas stream from an electrolytic urine pretreatment process was analyzed by gas chromatography-mass spectroscopy and wet chemical methods to determine its composition. The major constituents were identified as: hydrogen, carbon dioxide, oxygen, nitrogen, water vapor, and chlorine. The trace impurities were chlorinated light hydrocarbons, and a number of other organic impurities in the low ppm range. Several methods of removing all of the undesirable gases to levels acceptable for return to a space cabin atmosphere were investigated experimentally. A subsystem concept comprised of the following sequential unit processes and operations was successfully demonstrated: (1) raw urine scrubbing, (2) silica gel sorption, (3) dilution with cabin air, and (4) catalytic oxidation.
Colombo, G. V.↗
Theoretical and experimental studies of the deposition of Na2SO4 from seeded combustion gases
A basic point in the hot corrosion of turbine components is the deposition of sodium sulfate from flames containing sodium and sulfur. An experimental study is described which examines a dew point prediction theory based on the local thermochemical equilibrium (LTCE) method, and a means to calculate the deposition rate is suggested. In addition, a convective diffusion theory, based on the assumption of a chemically frozen boundary layer, utilizing the LTCE results, and imposing the additional effects of mass transport, was also successful in predicting dew points for Na2SO4-seeded combustion gases. A multicomponent mass transfer equation was derived to predict NaSO4 deposition rate via vapor transport at temperatures below the deposition onset temperature.
Kohl, F. J.↗
Analytical representation of elastic scattering cross sections of low energy electrons by atmospheric gases
Analytical representations of the elastic scattering cross sections of electrons with energies of 0.01-1 keV in atmospheric gases of N2, O2, O are given. These representations are suitable for the Monte Carlo method.
Ivanov, V. Y.↗
Operational experience in the Langley expansion tube with various test gases
A resume' of operating experiences with the Langley Expansion Tube is presented. The driver gas was unheated helium at a nominal pressure of 5000 psi and the majority of the data presented are for air and carbon dioxide test gases. The primary purpose of these data is to illustrate the effects of various parameters on quasi-steady test flow duration, as well as free stream and post-normal shock flow conditions. The discussion shows that the Langley Expansion Tube is an operational facility capable of producing good quality, highly repeatable, quasi-steady flow for test times sufficient to establish flow about blunt axisymmetric and two-dimensional models.
Miller, C. G.↗
Toxicity of pyrolysis gases from wood
The toxicity of the pyrolysis gases from nine wood samples was investigated. The samples of hardwoods were aspen poplar, beech, yellow birch, and red oak. The samples of softwoods were western red cedar, Douglas fir, western hemlock, eastern white pine, and southern yellow pine. There was no significant difference between the wood samples under rising temperature conditions, which are intended to simulate a developing fire, or under fixed temperature conditions, which are intended to simulate a fully developed fire. This test method is used to determine whether a material is significantly more toxic than wood under the preflashover conditions of a developing fire.
Hilado, C. J.↗
Toxicity of Pyrolysis Gases from Elastomers
The toxicity of the pyrolysis gases from six elastomers was investigated. The elastomers were polyisoprene (natural rubber), styrene-butadiene rubber (SBR), ethylene propylene diene terpolymer (EPDM), acrylonitrile rubber, chlorosulfonated polyethylene rubber, and polychloroprene. The rising temperature and fixed temperature programs produced exactly the same rank order of materials based on time to death. Acryltonitrile rubber exhibited the greatest toxicity under these test conditions; carbon monoxide was not found in sufficient concentrations to be the primary cause of death.
Hilado, Carlos J.↗
Effect of facility background gases on internal erosion of the 30-cm Hg ion thruster
Sputtering erosion of the upstream side of the molybdenum screen grid by discharge chamber ions in mercury bombardment thrusters was considered. Data which revealed that the screen grid erosion was very sensitive to the partial pressure of certain background gases in the space simulation vacuum facility were presented along with results of tests conducted to evaluate this effect. It is shown from estimates of the screen grid erosion in space that adequate lifetime for proposed missions exists.
Rawlin, V. K.↗
Measurement techniques for analysis of fission fragment excited gases
Spectroscopic analysis of fission fragment excited He, Ar, Xe, N2, Ne, Ar-N2, and Ne-N2 have been conducted. Boltzmann plot analysis of He, Ar and Xe have indicated a nonequilibrium, recombining plasma, and population inversions have been found in these gases. The observed radiating species in helium have been adequately described by a simple kinetic model. A more extensive model for argon, nitrogen and Ar-N2 mixtures was developed which adequately describes the energy flow in the system and compares favorably with experimental measurements. The kinetic processes involved in these systems are discussed.
Schneider, R. T.↗
Primordial noble gases in chondrites - The abundance pattern was established in the solar nebula
Ordinary chondrites, like carbonaceous chondrites, contain primordial noble gases mainly in a minor phase comprising not more than 0.05 percent of the meteorite, probably an iron-chromium sulfide. The neon-20/argon-36 ratios decrease with increasing argon-36 concentration, as expected if the gas pattern was established by condensation from the solar nebula, and was negligibly altered by metamorphism in the meteorite parent bodies. Meteoritic and planetary matter apparently condensed over a substantial range of temperatures.
Alaerts, L.↗
Electron impact on atmospheric gases. I - Updated cross sections
The analytic characterizations of electron impact cross sections for important atmospheric gases (namely, O2, N2, O, CO, CO2, and He) are updated. With these cross sections it is simple to communicate massive quantities of experimental and theoretical results. In addition, these forms are convenient for applications in energy degradation calculations, including a new approach described in a companion paper.
Jackman, C. H.↗
Electron impact on atmospheric gases. II - Yield spectra
A concept yield spectrum is introduced and this two-dimensional function is calculated, using a modified discrete energy bin method for 50-eV to 10-keV incident electrons impacting on the gases Ar, H2, H2O, O2, N2, O, CO, CO2, and He. The yield spectrum is amenable to physical interpretation, accurate analytic representation, and convenient application to the determination of all types of yields needed in aeronomical problems.
Green, A. E. S.↗
The origin and relative abundances of C, N and the noble gases on the terrestrial planets and in meteorites
Relative concentrations of noble gases and C and N are evaluated for the terrestrial planets. Comparisons between amounts of volatile materials in carbonaceous chondrites and on Earth and Mars are presented as support for the accretion model of planetary formation. However, attention is given to the large differences in the C/noble gas ratios on various bodies in the solar system, e.g. the Sun, Venus, Earth, Mars, stressing that the data are too incomplete to provide a reliable model for the sources of volatile and noble elements on the terrestrial planets.
Bogard, D. D.↗