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At least 1,621 records · Page 90
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

NO/+/ and O/+/ in the high latitude F-region

From an analysis of ionic reactions, it is deduced that NO(+) should be an important constituent of the high-latitude F-region. Owing to the rapid increase of the reaction O(+) + N2 yields NO(+) + N with ion velocity and temperature, high latitude electric fields and consequent E x B drifts act to deplete O(+) in favor of NO(+). As a consequence of this and the reduced rate of NO(+) dissociative recombination arising from high electron temperatures, it seems that NO(+) can, at times, replace O(+) as the major F2-region ion in the vicinity of the auroral ovals. The same processes should also be effective in creating nighttime electron density troughs composed primarily of NO(+) in regions equatorward of the auroral ovals where large electric fields are often present.

Banks, P. M.↗
NASA NTRS1974

Magnetic storm dynamics of the thermosphere

A theoretical study of the Dst component of magnetic storms is presented. The dynamic characteristics are found significantly different for Joule dissipation and electron precipitation, leading to the conclusion that the former is probably the predominant heat source for the upper thermosphere. Composition measurements on OGO-6, which reveal markedly different characteristics in N2, O and He, can be explained on the basis of energy advection and diffusive mass transport by thermospheric winds. Essential features in the F2-region response are explicable in terms of these dynamic processes. Electric field induced motions are estimated and it is concluded that resultant adiabatic heating could be significant.

Mayr, H. G.↗
NASA NTRS1975

Flow lasers

The present work reviews the fluid-mechanical aspects of high-power continuous-wave (CW) lasers. The flow characteristics of these devices appear as classical fluid-mechanical phenomena recast in a complicated interactive environment. The fundamentals of high-power lasers are reviewed, followed by a discussion of the N2-CO2 gas dynamic laser. Next, the HF/DF supersonic diffusion laser is described, and finally the CO electrical-discharge laser is discussed.

Christiansen, W. H.↗
NASA NTRS1975

Electron density decrease in SAR arcs resulting from vibrationally excited nitrogen

A study is made of the effect on theoretical electron-density profiles of vibrational enhancement in the rate of the reaction O(+) + N2 yields NO(+) + N. It is shown that the F-region electron-density depression that is observed in stable auroral red (SAR) arcs may be caused by vibrational excitation of molecular nitrogen.

Newton, G. P.↗
NASA NTRS1975

Preflight studies on tolerance of pocket mice to oxygen and heat. II - Effects on lungs

An electron microscope examination was carried out on the lungs of 11 pocket mice (Perognathus longimembris) that breathed oxygen at 10 psi or 12 psi partial pressure over a period of 7 d, at the end of which time they were decompressed to sea-level O2 pressure, either suddenly or in 30, 60, or 90 min. Vesiculation was noted in the endothelium of the alveolar-capillary wall in most of the animals and, occasionally, blebbing. Some mitochrondria were swollen in a few of the animals. Alveolar exudate was, in general, sparse. Compared with the lungs of other rodents, the lungs of pocket mice appeared relatively resistant to the toxic effects of oxygen. This conclusion needs, however, to be tempered by the fact that 5% N2 was used in the tests reported here. Nonetheless, the results suggest that the oxygen pressures anticipated on the flight of Apollo XVII should be well tolerated by the pocket mice.

Harrison, G. A.↗
NASA NTRS1975

Local time variation of equatorial thermospheric composition determined by the San Marco 3 Nace

The results of the Neutral Atmospheric Composition Experiment (Nace) on the Italian San Marco 3 satellite are analyzed. The analysis provides a comprehensive description of the daily variations in the densities of O, N2, Ar, and He in composition of the lower thermosphere, and also indicates that transport processes (possibly occurring elsewhere in the atmosphere) play an important part in the daily variation of the thermospheric composition at altitudes between 220 and 250 km.

Newton, G. P.↗
NASA NTRS1975

Phenomenological treatments of cross-sections for proton and hydrogen impact below 1 keV on molecular nitrogen

An analytic independent-particle model is used to construct static potentials to describe the interaction of hydrogen-like ions with atoms and molecules. Parameters of the ion-atom potential are determined from ab initio total energy minimization procedure. The elastic scattering of He(+) from Ne and Ar is investigated as a test case and comparison is made with experiment. The model is then used in conjunction with low energy H(+)-N2 experimental data to construct differential and total cross-sections for the scattering of protons and hydrogen in the energy range of 10 eV to 1 keV from molecular nitrogen. Analytic forms are used to parametrize these cross-sections to facilitate their use in the calculation of energy deposition by protons and hydrogen atoms in atmospheric gases.

Porter, H. S.↗
NASA NTRS1975

In situ measurements of plasma drift velocity and enhanced NO/+/ in the auroral electrojet by the Bennett spectrometer on AE-C

Simultaneous measurements of ion composition and plasma drift velocity by the Bennett mass spectrometer on the Atmosphere Explorer-C satellite reveal a direct correlation between enhancements in NO(+) concentration and ion drift velocity in the southern auroral oval. Low altitude (137 to 250 km) data obtained between 1700 and 2400 hr magnetic local time on October 22, 1974, reveal a region of westward plasma flow at velocities up to 1.3 km/s between 62 and 68 deg invariant latitude, with corresponding NO(+) enhancements of up to a factor of 20. A narrow region of reverse flow at about 0.9 km/s was also measured. These drift observations are consistent with convective flow patterns derived from electric field measurements, and their correlation with NO(+) appears to support the suggestion that NO(+) enhancements would be expected in regions of drift owing to the dependence on ion energy of the reaction O(+) + N2 yields NO(+) + N.

Brinton, H. C.↗
NASA NTRS1975

Atomic nitrogen measurements in the upper atmosphere

The open-source neutral mass spectrometer (OSS) on the Atmosphere Explorer-C satellite (AE-C) measures the neutral constituents of the upper atmosphere. It has been found that atomic nitrogen densities can be determined at altitudes above 380 km. Most of the nitrogen atoms combine with oxygen adsorbed on the walls of the ion source to form NO. The measured net peaks at 14 amu and 30 amu show the scale height expected for atomic nitrogen; both peaks have a pronounced diurnal variation. Absolute number densities at 400 km are computed for a time period between February and April 1974 when measurements were taken in the northern hemisphere. Minimum and maximum densities of atomic nitrogen occur between 4 and 6 hr LST in the morning and around 16 hr LST in the afternoon, respectively. At 400 km, the minimum particle density is 100,000/cu cm and the maximum density 1.5 million/cu cm. In contrast to the response of N2 to geomagnetic activity, atomic N shows no appreciable effect.

Mauersberger, K.↗
NASA NTRS1975

Effect of electric fields on the daytime high-latitude E and F regions

We have obtained solutions of the coupled continuity, momentum, and energy equations for NO(+), O(+), and O2(+) ions for conditions appropriate to the daytime high-latitude E and F regions. Owing to the rapid increase of the reaction O(+) + N2 yielding NO(+) + N with ion energy, high-latitude electric fields and consequent perpendicular-E x B drifts deplete O(+) in favor of NO(+). For electric field strengths less than about 10 mV/m the depletion of O(+) is small, and the altitude profiles of ion density are similar to those found at mid-latitudes. However, for moderate electric field strengths (50 mV/m), NO(+) is substantially increased in relation to O(+) and becomes an important ion throughout the F region. For large electric fields (200 mV/m), NO(+) completely dominates the ion composition to at least 600 km, decreasing at high altitudes with a diffusive equilibrium scale height. Since the overall F region electron density decreases markedly with increasing electric field strength, it appears that high-latitude, daytime electron density troughs are directly related to the presence of ionospheric electric fields.

Schunk, R. W.↗
NASA NTRS1975

The non-homogeneous accumulation model for terrestrial planet formation and the consequences for the atmosphere of Venus

The nonhomogeneous-accumulation model for the formation of the terrestrial planets is described, and its consequences for the formation of the Venusian atmosphere are assayed in the context of our knowledge of the composition of the earth and carbonaceous chondrites. The relative abundances of the low-temperature condensibles in the reservoirs at the earth's surface are applied to Venus. Although carbonaceous chondrites show similar properties for the chemically bound elements, they show large deficiencies for the rare gases. The major gases on Venus, by volume, are predicted to be 98.12% CO2, 1.86% N2 and 0.02% Ar-40.

Turekian, K. K.↗
NASA NTRS1975

Measurements of NH3 absorption coefficients with a C-13/O-16/2 laser

Measurements of NH3 absorption coefficients are presented for several transitions of a C-13(O-16)2 laser for small concentrations of NH3(p less than 1 torr) for absorption lines broadened to 1 atm with N2. NH3 absorption coefficients were determined for laser transitions R(8)(920.2194 wavelengths/cm) to R(28)(933.8808 wavelengths/cm) of the 00 1 - (10 0,02 0)I band. The strongest absorption coefficient K = 36.09 + or - 1.43 per (atm-cm) was measured for the R(18) transition for the NH3 line, aQ(6,6), and is larger than has been found in any previous measurements with a CO2 laser. The dependence of K on total pressure was also obtained for select transitions, and the frequency separation between the R(18) laser transition and the neighboring NH3 line aQ(6,6) was determined to be 550 + or - 50 MHz. These results are significant for long path absorption monitoring of NH3 with CO2 lasers since the path length can be reduced by approximately 40% and for heterodyne detection of NH3 since the relative position of the laser transition to the NH3 absorption line is well within the bandpass of Hg-Cd-Te photomixers.

Allario, F.↗
NASA NTRS1975

Exospheric temperature inferred from the Aeros-A neutral composition measurement

The derivation of exospheric temperature from satellite drag measurements is based on an assumption of invariant conditions of the neutral atmosphere at 120 km. Since it has been established that atomic oxygen, which is usually the major neutral constituent in the region of drag measurements, is subject to considerable variability with season, latitude, and solar and geomagnetic activity in the altitude region of 120 km, its value as an indicator of exospheric temperature is questionable. Ogo 6 neutral mass spectrometer measurements revealed that molecular nitrogen is a better indicator of exospheric temperature, since it is not subject to changes caused by eddy mixing and is therefore relatively less variable near the turbopause. However, theoretical arguments show that argon, even though it is a minor constituent, is relatively less variable with respect to changes in eddy diffusion coefficient and hence a better indicator of exospheric temperature than O and N2. In this paper the relative merits of these gases for deriving exospheric temperature are investigated by using observational data from the Aeros-A Nate experiment.

Chandra, S.↗
NASA NTRS1975

Effects of atomic nitrogen on the nocturnal ionosphere

Recently, atomic nitrogen densities of 50-500 million/cu cm were inferred in the daytime thermosphere from studies of the NI(2D-4S) 5200 A emission and from the photochemistry of various ion species using data measured by the Atmosphere Explorer-C satellite. In this paper we use the photochemistry of NO(+) and O2(+) at night to determine nocturnal N(4S) densities in the thermosphere. We present evidence for a missing source of NO(+) and a missing sink for O2(+) at night and show that this can be adequately supplied by the reaction O2(+) + N yields NO(+) + O if the N density at 200 km is about 7 million/cu cm. The atomic nitrogen has an important effect on studies of the 6300 A airglow. The omission of N in calculations of O(1D) using ground-based data results in an overestimate of the rate coefficient for quenching of O(1D) by N2.

Torr, M. R.↗
NASA NTRS1975

Winter bulge and diurnal variations in hydrogen inferred from AE-C composition measurements

In situ mass spectrometric measurements of ion and neutral particle thermospheric compositions have been used to infer the latitudinal and diurnal variations of thermospheric atomic hydrogen for solstice conditions. Local time-dependent and local time-independent components of the observed hydrogen distribution were separated on the basis of a model generated by expanding the log of neutral hydrogen concentration in terms of spherical harmonics. Results are compared with analogous data on N2 concentration; the comparison reveals an anticorrelation between gas temperature and hydrogen concentration. The slope of this anticorrelation line represents the 'zero flux condition' from the exosphere theory of Hodges (1973), thus further bearing out the conclusion that exospheric flow is the dominant process governing the global distribution of hydrogen.

Brinton, H. C.↗
NASA NTRS1977

Miniature carbon dioxide sensor

Infrared absorption spectrometer with dual wave length monochromator has several valuable features: 3.4 by 1.6 inch size; accuracy within plus or minus 5% from 0 to 30 mm Hg; instantaneous and temperature-independent response time; negligible O2 and N2 effects and less than 0.5% water vapor effect; 2.5 W power consumption; no moving parts; and 1.5 and 30 mm Hg CO2 in range.

Bordeaux, J.↗
NASA NTRS1975

Proposed geomagnetic control of semiannual waves in the mesospheric zonal wind

The polar semiannual oscillation in zonal wind explains midwinter weakening of the polar vortex and the relatively short stratospheric and mesospheric summer easterlies. The phase of the wind oscillation is equinoctial, as is the phase of the semiannual component in magnetic storm activity. For a given altitude, the contours of amplitude of the semiannual wind oscillation have less variability in geomagnetic than in geographic coordinates. It is suggested that the polar wind oscillations are caused by the semiannual maxima in magnetic storm activity, which lead to electron dissociation of O2 into O, in turn increasing ozone more rapidly than the dissociation of N2 destroys ozone, and inducing a semiannual variation in the thermal and wind fields. This implies that geomagnetic processes may cause or affect the development of sudden warmings. As the tropical semiannual wind oscillation is symmetric about the geomagnetic equator, the same processes may also influence the location of the tropical wind wave.

Belmont, A. D.↗