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Torr, M. R.

Publications and source records attributed to Torr, M. R..

At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Determination of the sources and sinks of N/+/ ions in the thermosphere

Measurements of atmospheric parameters made by the Atmosphere Explorer-C satellite used to identify mechanisms for the production and loss of N(+) ions in the ionosphere are presented. Photo-dissociative ionization of N2 is the main source below 250 km. Above 250 km the reaction O(+)(4S) + N(2D) yields N(+)(3P) + O(3P) is dominant, and a possible minor source of N(+) is the reaction O(+)(2P) + N2 yields N(+) + NO. Photoionization of N(4S) and dissociative charge exchange of He(+) with N2 constitute detectable sources above 350 km. Charge exchange of N(+) with O is a significant sink above 300 km, and the rate coefficients for these reactions are derived.

Torr, D. G.↗
NASA NTRS1979

An experimental and theoretical study of the mean diurnal variation of O/+/, NO/+/, O2/+/, and N2/+/ ions in the mid-latitude F1 layer of the ionosphere

A theoretical model of the diurnal variations in the compositions of the ions O(+), NO(+), O2(+) and N2(+) in the midlatitude F1 layer is presented and compared with measurements made by AE-C. The theoretical model includes the rate coefficients and branching ratios for the dissociative recombination of NO(+), O2(+) and N2(+) with electrons and the ion-atom interchanges of O(+) with N2 and N2(+) with O. Input parameters to the model comprise measurements of ion and electron temperatures, neutral atmosphere composition, the solar EUV flux and the photoelectron spectrum. In general, model calculations are found to agree with satellite measurements, confirming the major ion sources and sinks of the photochemical model, which has an accuracy of + or - 60%.

Torr, D. G.↗
NASA NTRS1979

Charge exchange of metastable 2D oxygen ions with molecular oxygen - A new source of thermospheric O2/+/ ions

Reactions involving metastable ions are difficult to study in the laboratory. Much new information on these reactions has been derived from satellite measurements of aeronomic parameters. In this paper, Atmosphere Explorer D data are used to study charge exchange of metastable O(+)(2D) ions with O2. Using direct measurements of the O2 at 200 km to compute O2 densities at 300 km and supporting ionic concentrations and temperature observations, we find the rate coefficient for this reaction to be 1 + or - 0.6 times 10 to the minus 9th cu cm/sec. The process constitutes a significant source of O2(+) ions in the F2 layer at times when the N2 and O2 densities are enhanced. This finding leads to the conclusion that charge exchange with O2 must be a major sink for O(+)(2D) and an important source of O2(+) ions in the E region, because of the increase in the O2 concentration/N2 concentration ratio with decreasing altitude. The results imply that 80% of all O(+) ions formed in the E region are converted to O2(+) and that only about 20% of the metastable O(+) ions are converted into N2(+) through charge exchange with N2.

Torr, D. G.↗
NASA NTRS1978

Zodiacal light dynamics experiment: A wideband imaging Fabry-Perot interferometer

The Solar Probe will provide an ideal platform from which to study dynamics of dust particles near the sun by measuring the detailed character of the Fraunhofer structure of the zodiacal light. The suggested instrument is a wideband imaging Fabry-Perot interferometer with state of the art technology in both the optics and the detector. The instrument would function as a high-resolution imaging device providing wavelength resolution of 0.03 A over about a 20 A range. The wideband imaging capability would provide sky maps of the zodiacal light on a despun spacecraft without mechanical scanning. The Solar Probe mission would allow the velocity distribution of the dust to be mapped along most of the trajectory of the spacecraft.

Torr, D. G.↗
NASA NTRS1978

Review of rate coefficients of ionic reactions determined from measurements made by the atmosphere explorer satellites

The large data base of aeronomic parameters measured by the Atmosphere Explorer C, D, and E satellites since December 1973 has been used to determine a number of reaction rate coefficients highly relevant to our understanding of thermospheric chemistry. In this paper the results are reviewed for ionic rate coefficients for recombination of NO(+), O2(+), for reactions of O(+) + N2, N2(+) + O, and O(++) + O, and for various reactions involving O(+)(2D) and O(+)(2P) ions with O and N2.

Torr, D. G.↗
NASA NTRS1978

The calculated and observed ionospheric properties during Atmospheric Explorer-C satellite crossings over Millstone Hill

Results are presented for calculated and observed incoherent scatter radar data on ionospheric and atmospheric properties during the crossings of the Atmospheric Explorer-C satellite over the Millstone Hill, Massachusetts incoherent scatter radar station. The incoherent scatter radar measured electron density vertical profiles and electron and ion temperatures. These values yielded the exospheric temperature and the vertical distribution of neutral gas temperature. The satellite measured electron and ion temperatures and densities, neutral gas composition, and photoelectron spectra. Measurements were also made of solar UV and EUV fluxes, the vertical profile of the NO number density, and the vertical profile of the 6300 A airglow-volume emission rate. The results are compared to those of a time-dependent coupled model of the ionospheric E- and F-regions. Good agreement is found between satellite results, incoherent scatter radar measurements, and model calculations. Along the orbital path satellite measurements show significant latitudinal gradients in the measured properties.

Roble, R. G.↗
NASA NTRS1977

Comparison between calculated and measured photoelectron fluxes from Atmosphere Explorer C and E

The two-stream method has been used to calculate photoelectron fluxes. These results have been compared to those obtained by the photoelectron spectrometer on Atmosphere Explorers C and E. At both low altitudes, and higher altitudes (where transport effects are significant) the calculated and measured photoelectron fluxes yield good agreement. It is suggested that (1) better photoionization and scattering cross-section data will yield improved flux calculations, and (2) measurements of the pitch angle distribution are necessary for better high-altitude comparisons.

Nagy, A. F.↗
NASA NTRS1977

The rate coefficient for the O/+/ + N2 reaction in the ionosphere

The rate coefficient for the reaction O(+) + N2 yields NO(+) + N is determined as a function of temperature from the photochemistry of NO(+) for both day and night conditions by using a large sample of simultaneous measurements of ion and neutral concentrations and temperatures made by the Atmosphere Explorer C satellite. The results cover the ion temperature range from 500 to 1200 K. Using recent flow-drift-tube results, the rate coefficient is calculated as a function of ion temperature and mean ion drift velocity for ionospheric conditions. The satellite and laboratory determinations are found to be in good agreement. Using this temperature dependence, an earlier determination of the dissociative recombination coefficient of NO(+) with electrons is refined.

Torr, M. R.↗
NASA NTRS1977

Satellite measurements of ionic concentrations applied to low altitude incoherent scatter interpretations

The determination of ion and electron temperatures and electron density from incoherent scatter radar data has in the past involved assumptions concerning the ionospheric composition below 250 km. Using a very large data base of measurements of O(+), O2(+), NO(+), and N2(+) made by the Atmosphere Explorer C satellite, a model has been developed of the ionic concentration between 130 and 300 km as a function of solar zenith angle. As the effect of the new model is to increase the radar determinations of the temperature, this may explain previous discrepancies between Langmuir probe and incoherent scatter temperatures, where the comparisons have been made at these low altitudes

Torr, M. R.↗
NASA NTRS1977

Determination of the rate coefficient for the N2/+/ + O reaction in the ionosphere

Using approximately 400 simultaneous measurements of ion and neutral densities and temperatures, and the spectrum of the solar flux measured by the Atmosphere Explorer C satellite, we have determined the rate constant k1 for the reaction between N2(+) and O in the ionosphere for ion temperatures between 600 and 700 K. We find that k1 = 1.1 x 10 to the minus 10th power cu cm per sec, with a standard deviation of + or - 15%. If we use the temperature dependence for this reaction determined in the laboratory then at 300 K we find excellent agreement with the recommended laboratory value.

Torr, D. G.↗
NASA NTRS1977

Doubly charged atomic oxygen ions in the thermosphere. I - Photochemistry

Measurements of O(++) concentrations made by the Atmosphere Explorer C satellite are analyzed for altitudes where photochemical equilibrium conditions prevail in order to determine the photochemical sources and sinks of the doubly charged ion. The major loss process is found to be through partial charge exchange with neutral atomic oxygen with a rate coefficient of 1 x 10 to the -11th cu cm/s with an uncertainty of 40%. Above 220 km the major source is photo-ionization of O(+). However, X ray ionization of O (at not greater than 23.3 A) producing O(++) directly through the Auger process provides a better fit to the observed profile at lower altitudes.

Breig, E. L.↗
NASA NTRS1977

Intercalibration of airglow observatories with the Atmosphere Explorer satellite

The visible airglow photometer on the Atmosphere Explorer C satellite has been used to compare the calibrations of a number of ground-based airglow observatories. Discrepancies between different ground stations as large as a factor of six have been revealed. Efforts to account for these discrepancies have resulted in the discovery of differences as large as a factor of two in the standard light sources in use at different observatories. The participation of additional observatories in the intercomparison of standard sources is solicited. The project has also led to the discovery of a source of error that can amount to another factor of two in the procedure used to calibrate many airglow instruments. In the course of the project, detailed maps based on satellite data have been made of the galactic and zodiacal-light background at a number of wavelengths, and a substantial source of contaminating emission has been discovered in the satellite data. The contamination appears to result from interaction of the spacecraft and the atmosphere at altitudes below 170 km.

Torr, M. R.↗
NASA NTRS1977

Electron and ion temperatures - A comparison of ground-based incoherent scatter and AE-C satellite measurements

The paper presents the results of comparisons of AE-C electron temperature of the ionosphere determined from the cylindrical electrostatic probe and the ion temperature of the ionosphere determined from the planar retarding potential analyzer with electron and ion temperatures determined from four incoherent scatter facilities: Arecibo, St. Santin, Millstone Hill, and Chatanika. Good agreement was obtained between the in situ and remote measurements of electron and ion temperatures. Longitudinal variations are found to be very important in the comparison of electron temperatures at some locations.

Benson, R. F.↗
NASA NTRS1976

Recombination of O2/+/ in the ionosphere

In spite of the excellent agreement between various laboratory measurements of the recombination rate of O2(+) with electrons, it is still questionable whether the laboratory results apply in the ionosphere, because although the radiative lifetime of vibrating O2(+) is not well known, indications are that it may be very long. Whether the laboratory results apply in the atmosphere depends on whether the recombination rate is dependent on the vibrational state of the O2(+) ion and on whether the ions are deactivated (or not) in both the laboratory experiments and the atmosphere prior to recombination. To obtain reliable answers to these questions, the present study was carried out to determine the recombination of O2(+) in the ionosphere from in situ measurements of the relevant temperatures and densities made by the open source mass spectrometer carried by the AE-C satellite. The photochemistry involved is discussed. The results show that the ionospheric determination of the recombination rate of O2(+) with electrons agrees with the laboratory measurements of Walls and Dunn (1974) for electron temperatures between 1200 and 2000 K.

Torr, D. G.↗
NASA NTRS1976

Global characteristics of 0.2 to 26 keV charged particles at F region altitudes

Measurements have been made by the low energy electron experiment (LEE) on the Atmosphere Explorer-C satellite (AE-C) of electrons and protons in the energy range 0.2 to 26 keV. Data taken in the altitude range 250 to 300 km during the period 15 December 1973 to 25 May 1975 are analyzed. Measurements were made over a range of magnetic latitudes extending from the equator to 80 deg. The average electron flux at midlatitudes at night is found to be about (1-5) x 10 to the -4 ergs/sq cm/s, and increases by about an order of magnitude during the day. The upper limit for the nighttime and daytime proton energy flux is about 1 x 10 to the -4th ergs/sq cm/s. The total nighttime energy flux will result in a production rate of .3 to 10 ions/cu cm/s at the base of the F region and in the D region, respectively, and should constitute an important source of ionization in the nocturnal ionosphere.

Torr, D. G.↗
NASA NTRS1976

Recombination of NO/+/ in the ionosphere

Simultaneous nighttime measurements of ion and neutral concentrations and temperatures made by the Atmosphere Explorer-C satellite were used to determine the recombination rate coefficient of NO(+) as a function of electron temperature. The results agree in shape and absolute magnitude to within one standard deviation with those of Walls and Dunn (1974), indicating that NO(+) ions in the ionosphere may be in the ground vibrational state.

Torr, D. G.↗