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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Molecular ions in the F2 layer.

Data on ion concentrations at heights of 400-500 km, obtained by the OGO VI satellite, suggest that the O(+) and molecular ion concentrations are sometimes anticorrelated. To assist in explaining this phenomenon, a table of the chemical reactions most likely to control the molecular ion concentrations is drawn up, and its validity tested with the aid of data from rocket-borne mass spectrometers at heights of 220-400 km. The anticorrelation of O(+) and NO(+) ions by day is thought to be due to the importance of a reaction between N2(+) ions and O atoms; the main source of N2(+) above 300 km is probably charge-exchange between N2 and O(+), the latter being produced by photoionization. However, at night another source of NO(+) ions is required, which may be N(+) ions that are either stored in the magnetosphere or are produced from He(+) and N2.

Rishbeth, H.↗
NASA NTRS1973

Magnetospheric convection and the high latitude F2 ionosphere

Behavior of the polar ionospheric F-layer as it is convected through the cleft, over the polar cap, and through the night side F-layer trough zone was investigated. Passage through the cleft adds of the order of 200,000 ions/cu cm in the vicinity of the F 2 peak and redistributes the ionization above approximately 400 km altitude to conform with an increased electron temperature. The F-layer is also raised of the order of 20 km in altitude by the convection electric field. In the night soft electron precipitation zone, the layer is lowered in altitude by the convection electric field, and then decays, primarily by chemical recombination, as it convects equatorward and around the dawn side of the earth. In the absence of ionization sources, decay by factors of the order of 100 to 1000 occur prior to entry into the sunlit hemisphere, thus forming the F-layer night trough.

Knudsen, W. C.↗
NASA NTRS1975

Influence of thermal plasma flow on the daytime F2 layer

Previous work on theoretical modeling of thermal plasma flow between the ionosphere and the plasmasphere on the night side of the earth, where photoionization is almost completely absent, is continued to cover ionosphere-magnetosphere coupling in the dayside ionosphere. Results indicate that the daytime plasmapause should be associated with the H(+) trough in the top-side ionosphere, but not with the trough in O(+) density or NmF2. At night the plasmapause can be identified with a trough in both H(+) and O(+) densities.

Park, C. G.↗
NASA NTRS1975

Depletion of the F2 region ionosphere and the protonosphere by the release of molecular hydrogen

Theoretical models have been used to investigate the effects of artificially injected H2 gas on plasma densities in the ionospheric F region and the overlying protonosphere. Owing to large reaction rates between H2 and ionospheric O(+) ions, plasma densities in both daytime and nighttime ionospheres can be greatly reduced by modest amounts of released H2 gas. One hundred kg of H2 released at 300-km altitude reduces local O(+) densities by more than three orders of magnitude and produces about a 5% depression in H(+) densities in the overlying protonosphere. These results suggest that it should be possible to conduct controlled chemical-modification experiments for investigation of many outstanding ionospheric and magnetospheric problems.

Bernhardt, P. A.↗
NASA NTRS1978

An assessment of an F2 or N2O4 atmospheric injection from an aborted space shuttle mission

Assuming a linear relationship between the stratosphere loading of NOx and the magnitude of the ozone perturbation, the change in ozone expected to result from space shuttle ejection of N2O4 was calculated based on the ozone change that is predicted for the (much greater) NOx input that would accompany large-scale operations of SSTs. Stratospheric fluorine reactions were critically reviewed to evaluate the magnitude of fluorine induced ozone destruction relative to the reduction that would be caused by addition of an equal amount of chlorine. The predicted effect on stratospheric ozone is vanishingly small.

Watson, R. T.↗
NASA NTRS1986

A factor of 2 reduction in theoretical F2 peak electron density due to enhanced vibrational excitation of N2 in summer at solar maximum

The degree to which the O(+) + N2 reaction rate is increased as a result of enhanced vibrational excitation of the N2 molecule in the thermosphere was investigated. It is found that the reaction rate may be sufficiently elevated in summer at solar maximum to decrease the peak O(+) density by a factor of 2, but there is only a small reduction in the winter peak density. Therefore the vibrational excitation of N2 acts to increase the magnitude of the seasonal anomaly. This work emphasizes the need for more laboratory work to clear up uncertainties in some of the key parameters.

Richards, P. G.↗