Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “NEUTRALIZATION”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 631 records · Page 35
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Seasonal effects on distributions of minor neutral constituents in the mesosphere and lower thermosphere.

Calculations have been made of the diurnal variations in minor neutral constituents in the mesosphere and lower thermosphere for the condition of 60 deg latitude, summer and winter. Excited molecular oxygen has been added, and the effects of absorption of Schumann-Runge bands have been taken into account. The results show significant seasonal differences, which may be interpreted mainly in terms of the difference of penetration of solar radiation and the duration of sunlit hours. However, the comparison of the observed seasonal and diurnal variations in the airglow emissions from hydroxyl, atomic oxygen (5577 A), and excited molecular oxygen with those calculated from models suggests that effects of large-scale meridional circulation (horizontal and vertical transports) may be important in explaining these observations. It is shown that the concentration of the constituents whose main loss mechanism is recombination with atomic oxygen decreases sharply above 80 km.

Shimazaki, T.↗
NASA NTRS1972

Neutral-particle wake method for measuring the atmospheric temperature from a satellite.

Description of a method that would permit a satellite-borne neutral mass spectrometer to measure the atmospheric temperature. The spectrometer examines the partial pressure variations that occur as the wake of a small rectangular baffle is swept across the entrance orifice of the spectrometer. For a given baffle size and for a mounting distance from the orifice, the depth of the resulting pressure minimum depends only on the thermal velocity or temperature of the observed species. The validity of the method can be checked by measuring the wake characteristics of more than one species and/or by employing each of several baffle sizes. The theory includes the effect of a finite orifice size, finite baffle length, and the backscattering of particles from the baffle into the orifice. It is found that a suitable baffle arrangement can be achieved that will permit the temperature to be measured over at least the range normally encountered in the thermosphere (200 to 2000 K) and, depending on the sensitivity and background pressure of the spectrometer, over an altitude range of about 140 to 600 km.

Brace, L. H.↗
NASA NTRS1972

Response of the neutral particle upper atmosphere to the solar eclipse of 7 March 1970.

Results of soundings with a series of five pitot probes launched in conjunction with the solar eclipse of Mar. 7, 1970. Three soundings were programmed to occur at 40, 80, and 100% obscuration of the sun (at 100 km) during a 42-min period. The remaining two soundings were made 24 hr before and after the eclipse. The five soundings yielded neutral particle pressure, temperature, and density profiles over the altitude regime from 30 to 125 km. Below 95 km, the three density profiles resulting from the eclipse day launches had an average deviation of less than 1.5%. Above 95 km, density changes of up to 20% were observed. Such changes in density are comparable in magnitude to those normally observed over a period of several hours. On Mar. 10, 1971, three additional pitot probes were launched at times identical to those of the 1970 eclipse day. Comparison of the two sets of data should provide for a more objective analysis regarding atmospheric response to solar input.

Horvath, J. J.↗
NASA NTRS1972

Neutral winds implied by electron content observations during the 7 March 1970 solar eclipse.

Measurements of columnar electron content using geostationary satellite signals were made at several of our observatories throughout the U.S., during the 7 March 1970 solar eclipse. The ionospheric response to the solar eclipse was simulated in a computer. Discrepancies between observed and simulated electron content behaviors can be greatly reduced by assuming the existence of plausible neutral winds originated by the eclipse in the F-region heights.

Almeida, O. G.↗
NASA NTRS1972

Thermospheric observations combining chemical seeding and ground-based techniques. I - Winds, turbulence and the parameters of the neutral atmosphere.

Two Skylark sounding rockets carrying chemical seeding payloads were launched from Woomera, South Australia (31 S, 137 E) in October 1969. In conjunction with these firings, the University of Adelaide conducted ground-based experiments on the upper atmosphere using the radio meteor and spaced receiver drift methods. This paper presents the measurements of properties of the neutral atmosphere above 90 km which were obtained from these experiments.

Lloyd, K. H.↗
NASA NTRS1972

Local behavior of autonomous neutral functional differential equations.

Basic problems for a special class of neutral functional differential equations (NFDE) are formulated, and some contributions to a general qualitative theory in the neighborhood of an equilibrium point are indicated. The properties of a NFDE (G,f) are examined to determine in what sense these properties are insensitive to small changes in (G,f) in the topology G x F. The special class of equations that is introduced includes retarded functional differential equations and difference equations.

Hale, J. K.↗
NASA NTRS1972

North-South asymmetry of the neutral exosphere.

A systematic asymmetry in the neutral exosphere between the Northern and Southern Hemispheres has been identified for the first time after correcting for all other known systematic variations. This phenomenon was clearly detected from recent measurements of helium drag effects near 1000 km on the low mass-to-area ratio Explorer 19 satellite. From a reanalysis of all four NASA Langley Air Density Explorer satellites (Explorers 9, 19, 24, and 39), this systematic asymmetry was traced over an entire solar activity cycle. It was found that helium concentrations in local summer at high latitudes are generally more than 50% lower in the Southern Hemisphere than in the Northern Hemisphere. In addition, the increase in helium concentrations from summer to winter was found to be approximately 80% greater in the Southern Hemisphere than in the Northern Hemisphere.

Keating, G. M.↗
NASA NTRS1972

Measurement of the neutral composition of the lower thermosphere above Fort Churchill by rocket-borne mass spectrometer.

Measurement of the neutral atmospheric composition above Fort Churchill, Canada (59 N, 94 W), by mass spectrometers in two rocket flights at 0835 CST on Feb. 4 and 6, 1969. A quantitative measure for the extent of agreement with static diffusive equilibrium is introduced, and substantial agreement with profiles predicted when static diffusive equilibrium was assumed is found for all constituents including helium. A sensitive search for atomic nitrogen yielded upper limits of a few per cent for one flight and of 0.2% for the other.

Hickman, D. R.↗
NASA NTRS1972

Neutral composition in the thermosphere.

Data obtained from the Ogo 6 neutral atmospheric composition (NAC) experiment for a period of more than 1 year are used to compare the average constituent composition at an altitude of 400 km with that predicted by the Jacchia 1971 and 1965 models. The comparison shows that the Jacchia 1971 model underestimates the molecular nitrogen densities at 400 km by a factor of 2. An atmosphere is constructed down to 120 km by means of the Stein and Walker technique. A fit is made with (1) the 400-km total densities from drag measurements and the composition from Ogo 6 NAC, (2) the 250-km measured molecular nitrogen densities, and (3) the 150-km total densities from drag. This fit shows that the Jacchia 1971 model overestimates the atomic oxygen content at 150 km.

Taeusch, D. R.↗
NASA NTRS1972

Smoothing properties of neutral equations

A neutral functional differential equation is defined as d/dt(Dx sub t) = f(x sub t), with D linear, continuous, atomic at zero. The solution generally is no smoother than the initial data after any finite number of steps. A more restrictive class of D-operators for which some smoothing takes place after an infinite number of steps is defined. This result indicates that a solution can be in an omega-limit set only if it corresponds to initial data which are smooth. A space which can be considered as a Banach space with the topology of uniform convergence is also defined.

Hale, J. K.↗
NASA NTRS1972

Neutral atmospheric models compatible with satellite orbital decay and incoherent scatter measurements

A correlation study was made of the variations of the exospheric temperature extrema with various combinations of the monthly mean and daily values of the 2800 MHz and Ca:2 solar indices. The phase and amplitude of the semi-annual component and the term dependent on Kp were found to remain almost the same for the maximum and minimum temperature. The term dependent on the 27 day component of the solar activity was found to be about four times as large for the diurnal maximum as for the minimum. Measurements at Arecibo have shown that temperature gradient changes at 125 km are consistent with the phase difference between the neutral temperature and density maxima. This is used to develop an empirical model which is compatible with both the satellite measurements and the available incoherent scatter measurements. A main feature of this model is that day length is included as a major model parameter.

Rohrbaugh, J. L.↗
NASA NTRS1973

Microbiological assay of the Marshall Space Flight Center neutral buoyancy simulator

A neutral buoyancy simulator tank system is described in terms of microbiological and medical safety for astronauts. The system was designed to simulate a gravity-free state for evaluation of orbital operations in a microorganism-free environment. Methods for the identification and elimination of specific microorganisms are dealt with as measures for a pure system of space environment simulation.

Beyerle, F. J.↗
NASA NTRS1973

OGO-6 neutral atmospheric composition experiment

The continued analysis of data obtained from the neutral atmospheric composition experiment flown on OGO-V6 is discussed. The effort was directed toward the study of five specific areas of interest for which the OGO-V6 data were especially useful.

Taeusch, D. R.↗
NASA NTRS1972

Neutral hydrogen in cometary comas.

The strong L alpha radiation observed recently in comets Tago-Sato-Kosaka and Bennett can be explained in terms of the resonant scattering of solar L alpha radiation on neutral hydrogen formed by the photodissociation of H2O which is vaporized from a nucleus having an ice core. A complete hydrodynamic description of an atmosphere composed of H2O and its daughter products OH, H and O coupled through frictional interaction as well as production and loss processes is given. Numerical results are computed in a typical case, and it is found that a temperature of about 3000 K for the cometary atmosphere provides the best fit with observation.

Mendis, D. A.↗
NASA NTRS1972

Control of functional differential equations of retarded and neutral type to target sets in function space.

Optimal control of systems governed by functional differential equations of retarded and neutral type is considered. Problems with function space initial and terminal manifolds are investigated. Existence of optimal controls, regularity, and bang-bang properties are discussed. Necessary and sufficient conditions are derived and several solved examples which illustrate the theory are presented.

Banks, H. T.↗
NASA NTRS1973

Neutral thermosphere temperatures from density scale height measurements.

During each 4-min satellite interrogation period the Explorer 32 density gages measured the atmospheric density approximately every 2 sec. Over certain segments of the satellite orbit these measurements determined the neutral atmospheric density scale height. The scale heights measured at an altitude of 400 (plus or minus 50) km have been analyzed to infer thermospheric temperatures. The results confirm an earlier conclusion from the density data of the same experiment that the diurnal temperature variation is latitude dependent.

Newton, G. P.↗
NASA NTRS1973

Auroral heating and the composition of the neutral atmosphere.

Heating of the neutral atmosphere by auroral particle fluxes and by orthogonal electric fields is responsible for large changes in the thermospheric composition that have been observed by satellite mass spectrometers. Vertical winds of a few meters per second are produced in the region subject to auroral heating; this vertical upwelling drives circulation cells that extend the effects of heating in the auroral region on a global scale. Our analysis focuses on the initial phase of a magnetic storm within the auroral region.

Hays, P. B.↗