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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 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

A presentation of base heating data obtained from the 25-O space shuttle model at high altitude

During development of the 25-O space shuttle model, several test firings were made in a vacuum chamber at simulated altitude conditions in order to verify satisfactory ignition and operation of the model in a high altitude environment. In conjunction with these firings, heating rate and pressure measurements were obtained at several locations in the orbiter base region on a piggy-back basis. Data obtained during these experiments are summarized, the 25-O space shuttle model is described.

Hendershot, K. C.↗
NASA NTRS1974

Monte Carlo analysis of the solar-wind modulation of galactic C-N-O at solar maximum

A previous (Moss and Giuli, 1971) Monte Carlo analysis of the solar-wind modulation of galactic cosmic-ray rigidity spectra is extended to include particles in the C-N-O group. A solar cavity 'radius' of 7 AU is found to be consistent with observations of the C-N-O component at solar maximum. The variation in modulation between solar maximum and solar minimum may be explained solely by variation of the solar cavity size, with no change in the scattering mean free path.

Moss, T. A.↗
NASA NTRS1974

An upper limit to the product of NO and O densities from 105 to 120 km

From the Ogo 6 horizon-scanning-photometer data a useful upper limit can be set to the radiance of nightglow in the O-NO afterglow continuum above 105 km. The upper limit is a factor of about 5 less than the product of observed NO densities and Jacchia (1971) O model densities.

Donahue, T. M.↗
NASA NTRS1974

Determination of the rate constant for the reaction O + NO yields N + O2

A shock-tube technique was used to determine the rate constant for the reaction O + NO yields N + O2 in the 2500-4100 K range. Mixtures of NO, N2O, and an inert gas (Ar or Kr) were shock-heated, and the decay of infrared emission from the fundamental vibration-rotation band of NO at 5.3 microns was monitored. The N2O dissociates quickly to provide a source of O atoms for the above reaction. An expression for the rate constant is derived which fits these data and previous data at higher and lower temperatures.

Hanson, R. K.↗
NASA NTRS1975

Dissociative recombination source for O I /1D/ atoms

A study of the nighttime dissociative recombination production of O(1D) is reported. The data were gathered by a rocket payload carrying an ion mass spectrometer, Langmuir probe, retarding potential analyzer, and 6300-A photometer. The specific recombination rate to produce O(1D) atoms is deduced to be (2.8 + or - 1.0) times 10 to the minus 8th cu cm per sec and is 30% of the total laboratory rate. The quenching rate at 250 km is 0.0044 + or - 0.0015 per sec.

Sharp, W. E.↗
NASA NTRS1976

The reactions of O(ID) and OH with CH3OH, oxidation of the HCO radial, and the photochemical oxidation of formaldehyde

An experimental, laboratory study of the various photochemical reactions that can occur in the mesosphere and stratosphere is presented. N2O was photolyzed at 2139 A in the presence of CH3OH and CO. The O(id) produced in the photolysis reacted with CH3OH to produce OH radicals, and thus the reactions of both O(id) and OH were able to be studied. Also considered was the oxidation of the HCO radical. Mixtures of Cl2, O2, H2CO, and sometimes N2 or He were irradiated at 3660 A at several temperatures to photodecompose the Cl2. The photochemical oxidation of formaldehyde was studied as follows: formaldehyde in the presence of N2 and/or O2 (usually dry air) was photolyzed with a medium pressure Hg lamp used in conjunction with various filters which transmit different relative amounts of Hg lines from 2894 A to 3660 A. Results are presented and discussed, along with a description of experimental procedures and apparatus, and chemical reaction kinetics.

Osif, T. L.↗
NASA NTRS1975

Interactions of 2.1 GeV/n He-4, C-12, N-14 and O-16 nuclei in emulsion

The interaction mean-free-path lengths for He-4, C-12, N-14 and O-16 nuclei at 2.1 GeV/n have been measured in nuclear emulsion detectors. The angular distributions of Z equals 1 and 2 secondaries from the interactions of C, N and O beams are determined, and the topology of projectile fragmentation of these ions is examined.

Heckman, H. H.↗
NASA NTRS1976

Absolute rate constants for O + NO + N2 yields NO2 + N2 from 217-500 K

Rate constants for the reaction O + NO + N2 yields NO2 + N2 from 217 to 500 K were obtained by a method combining the flash photolysis of NO with the time resolved detection of O by means of resonance fluorescence. The rate constants were found to obey the Arrhenius equation k = (15.5 plus or minus 2.0) x 10 to the -33rd exp((1160 plus or minus 70)/1.987 T) cm to the 6th/squared molecule/s, while the temperature dependence of k is described by k = 3.80 x 10 to the -27th/T to the 1.82 cm to the 6th/squared molecule/s.

Whytock, D. A.↗
NASA NTRS1976

Absolute rate constants for O + NO + M /= He, Ne, Ar, Kr/ yields NO2 + M from 217-500 K

Rate constants for the reaction O + NO + M yields NO2 + M have been obtained at temperatures from 217-500 K in four different rare gases by a method combining flash photolysis with time resolved detection of O(3-P) by resonance fluorescence. The measured rate constants in Arrhenius form are (10.8 plus or minus 1.2) x 10 to the -33rd exp(1040 plus or minus 60/1.987 T) for helium; (9.01 plus or minus 1.16) x 10 to the -33rd exp(1180 plus or minus 70/1.987 T) for argon; (9.33 plus or minus 1.10) x 10 to the -33rd exp(1030 plus or minus 60/1.987 T) for neon; and (9.52 plus or minus 1.10) x 10 to the -33rd exp(1140 plus or minus 70/1.987 T) for krypton in units of cm to the 6th/sq molecule/s.

Michael, J. V.↗
NASA NTRS1977

Kinetics of the reactions of ClO with O and with NO

The rate constants k1, k2, and k3 for the reactions Cl + O3 yields ClO + O2 (1), ClO + O yields Cl + O2 (2), and ClO + NO yields Cl + NO2 (3), respectively, were measured by the discharge-flow technique, in which chlorine atoms are added to a flow of O3 and either O or NO in a helium carrier gas. The conditions of the experiment were such that the steady-state concentration ratios of Cl to ClO are simply interpretable in terms of the rate constant ratios k2/k3 or k3/k1. These rate constant ratios were measured over the range 220 to 298 K and combined with the directly determined k1 value to yield k2 and k3. The results are: k1 = 2.12 x 10 to the -11th exp(-157/T); k2 = 3.38 x 10 to -11th exp(75 plus or minus 40/T); and k3 = 1.13 x 10 to the -11th exp(200 plus or minus 30/T) cu cm/sec.

Zahniser, M. S.↗
NASA NTRS1978

Effect of hydraulic fluid (MIL-H-83282) on selected commercial O-ring compounds

Acrylonitrile and fluorocarbon compounds were evaluated at various temperatures and time intervals in samples of the fluid obtained from three qualified suppliers. It was concluded that both polymers can function in hydraulic fluids within the conditions defined by this study. Hydraulic fluid from each manufacturer was similar in its effect upon each given O-ring material, with one exception. Similarly, there were no striking differences in the resistance of O-rings of the same generic rubber type when provided by the different manufacturers.

Wood, T. E.↗
NASA NTRS1977

Stiffness and damping of elastomeric O-ring bearing mounts

A test rig to measure the dynamic stiffness and damping of elastomer O rings was described. Test results for stiffness and loss coefficient in the frequency range from 50 Hz to 1000 Hz are presented. Results are given for three different materials, for five temperatures, for three amplitudes, for five values of squeeze for three values of stretch for three values of cross-section diameter and for three values of groove width. All test data points were plotted. In addition, trend summary plots were presented which compare the effect of material, temperature, amplitude, squeeze, stretch, cross-section diameter, and groove width. O ring deflections under a static load for different material were presented; and effective static stiffness values were compared with dynamic values.

Smalley, A. J.↗
NASA NTRS1977

The design of an Fe-12Mn-O.2Ti alloy steel for low temperature use

An investigation was made to improve the low temperature mechanical properties of Fe-8 approximately 12% Mn-O 2Ti alloy steels. A two-phase(alpha + gamma) tempering in combination with cold working or hot working was identified as an effective treatment. A potential application as a Ni-free cryogenic steel was shown for this alloy. It was also shown that an Fe-8Mn steel could be grain-refined by a purely thermal treatment because of its dislocated martensitic structure and absence of epsilon phase. A significant reduction of the ductile-brittle transition temperature was obtained in this alloy. The nature and origin of brittle fracture in Fe-Mn alloys were also investigated. Two embrittling regions were found in a cooling curve of an Fe-12Mn-O 2Ti steel which was shown to be responsible for intergranular fracture. Auger electron spectroscopy identified no segregation during solution-annealing treatment. Avoiding the embrittling zones by controlled cooling led to a high cryogenic toughness in a solution-annealed condition.

Hwang, S. K.↗
NASA NTRS1977

A local earthquake coda magnitude and its relation to duration, moment M sub O, and local Richter magnitude M sub L

A relationship was found between the seismic moment, M sub O, of shallow local earthquakes and the total duration of the signal, t, in seconds, measured from the earthquakes origin time, assuming that the end of the coda is composed of backscattering surface waves due to lateral heterogenity in the shallow crust following Aki. Using the linear relationship between the logarithm of M sub O and the local Richter magnitude M sub L, a relationship between M sub L and t, was found. This relationship was used to calculate a coda magnitude M sub C which was compared to M sub L for Southern California earthquakes which occurred during the period from 1972 to 1975.

Suteau, A. M.↗
NASA NTRS1979

Observed distribution functions of H, He, C, O, and Fe in corotating energetic particle streams: Implications for interplanetary acceleration and propagation

Distribution functions for H, He, C, O, and Fe derived from our IMP 8 measurements of approximately 0.15 to approximately 8 MeV/nucleon particles in three corotating streams observed near earth are shown to have a simple exponential dependence on the particle speed. The e-folding speed, v sub o, is typically 0.01c, is found to be the same for the distribution functions of all elements examined, and varies little from one corotating event to the next. The relative abundances of energetic particles in these events resemble most closely the solar coronal composition and, thus, presumably that of the solar wind. These results may imply that the acceleration of these particles, which occurs in corotating interaction regions at several AU from the sun, is by a statistical process.

Gloeckler, G.↗
NASA NTRS1978

Temperature and ionization balance dependence of O VII line ratios

The forbidden-plus-intersystem to resonance line ratio (G) for the heliumlike ion O VII is calculated, taking into account cascades, blended satellite lines, and radiative plus dielectric recombination. It is noted that G is of particular use for investigating radiative-transfer effects and nonequilibrium ionization in the solar corona and that the calculations are applicable to a low-density optically thin Maxwellian plasma. The temperature dependence of G is considered for the case of a steady-state equilibrium plasma, and the effect of departures from ionization equilibrium on G is examined. It is found that G is quite insensitive to temperature over the range from 600,000 to 6 million K for a steady-state plasma, but that recombinations may be suppressed or dominant, depending on the relative abundance of O VIII, for a plasma in which the state of ionization is not in equilibrium with the electron temperature. This latter effect is shown to be capable of causing large variations in G that are dependent on electron temperature.

Acton, L. W.↗
NASA NTRS1979

Counterstreaming of O+ and H+ ions in the plasmasphere

Although the ion flux along plasmaspheric flux tubes has been both measured and numerically modeled for many years, it is only recently that H(+)-O(+) counterstreaming, with O(+) upwards, has been studied. The theoretical studies indicate that counterstreaming occurs under special conditions primarily near twilight. It is shown that such counterstreaming arises not only from a combination of particular conditions but is a more fundamental characteristic of the flow of plasma in the closed field-line magnetosphere. The causes of counterstreaming are analyzed showing that it must occur under steady state conditions; it is also shown how diurnal variations modify the steady state pattern.

Young, E. R.↗
NASA NTRS1980

The behavior of the O/+/-H/+/ transition level at solar maximum

An examination of the transition level at which the ionospheric ions O(+) and H(+) are equal in concentration has been carried out by using the retarding potential analyzer data from the OGO 6 satellite. Between dip latitudes of 0 and 50 deg the transition level shows a much more pronounced latitude dependence during solar maximum than during solar minimum. The longitude dependence of the transition level features indicates the roles that zonal and meridional F region winds might play in the distribution of O(+) and H(+) in the low- and mid-latitude ionosphere.

Kutiev, I.↗