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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 145 records · Page 8
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NASA NTRS1978

Fe/+/ ions in the high latitude F-region

Ion mass-spectrometer measurements on Atmosphere Explorer C orbits from December 1974 to December 1976 were surveyed poleward of + or - 30 deg for instances in which the Fe(+) number density exceeded the spectrometer threshold sensitivity of 30/cu cm. The occurrences of Fe(+) within the altitude range covered by the orbit, 220 to 320 km, revealed a distinct pattern apparently associated with regions of upward plasma transport. At night a band of such events occurred between 50 and 60 deg invariant latitude, which typically corresponded to the location of the main ionospheric trough. In this region large upward ion drifts due to the drag of an equatorward-blowing neutral wind are expected. The Fe(+) band extends past 0600 MLT to about 1100 MLT during the summer, but is not observed in the afternoon. The dayside distributions possibly result from the upward drifts of F-region ions detected by backscatter techniques after dawn during summer. At higher latitudes patches of Fe(+) were detected in regions where strong plasma drifts often prevail and hence where poleward E x B drift motions and atmospheric expansion through Joule heating can lift the ions upwards.

Grebowsky, J. M.↗
NASA NTRS1973

Nighttime ion composition measurements at the geomagnetic equator

Two ion composition profiles, representative of the nighttime equatorial ionosphere between 90 km and 300 km, are presented. These profiles were obtained by two rocket-borne ion mass spectrometers on a single night for solar zenith angles of 112 deg and 165 deg. For both flights, the principal ion above 200 km is O(+). The downward drift of the atomic ions O(+) and N(+), coinciding with the postsunset lowering of the F2 peak, is observed through an enhancement of the density of O(+) at altitudes above 200 km and N(+) above 240 km. Below the drift region, O(+) and N(+) are observed in concentrations larger than expected. The NO(+) altitude distribution retains its shape throughout the night, and below 210 km, is the principal ion. The behavior of O2(+) can be explained by the O(+), electron density and theoretical neutral nitric oxide concentrations. Light metallic ions, including Mg(+), Na(+), and possibly Si(+), are observed to altitudes approaching 300 km and are affected by vertical drift.

Goldberg, R. A.↗
NASA NTRS1974

Initial ion composition results from the Isis 2 satellite

Isis 2 satellite carried, among other ionospheric instruments an ion mass spectrometer designed to measure the composition of the ionosphere in the mass range from 1 to 64 amu. The satellite, in a nearly constant 1400-km orbit, was launched on April 1, 1971. Examples of data show a wide variation in ion composition from 99% H(+) at night near the equator to greater than 95% O(+) and N(+) in the daytime poleward of the plasmapause. Both H(+) and He(+) are observed to be streaming outward from the high-latitude regions with velocities of several kilometers per second (the polar wind), determined from phase shifts in roll modulation maximums between light and heavy ion species. During the August 1972 magnetic storm a unique ionosphere developed, consisting of N(+) as the dominant species between 55 and 80 deg invariant latitude (above the plasmapause) and N2(+), NO(+), and O2(+) at the 1000 per cu cm concentration level, whereas these molecular species are usually below the detection limit of 1 ion per cu cm in quiet times at this altitude.

Hoffman, J. H.↗
NASA NTRS1973

Zonal drifts of irregularities imparted by meridional winds.

In a uniform ionosphere, meridional winds cause only meridional motions of irregularities. It is shown, however, that, if F-region irregularities are considered in a real ionosphere in which there is a highly conductive E-layer, zonal motions occur. During the day a substantial westward drift takes place, while at night the drift is eastward but smaller, owing to the much smaller E-layer conductivity. Thus, the effect of meridional winds is to impart a net westward drift to small irregularities in the ionization, provided such irregularities persist long enough.

Waldman, H.↗
NASA NTRS1982

A new concept of plasma motion and planetary magenetic field for Venus

It is shown that the magnetohydrodynamic conditions of the Venus ionosphere near the terminator favor convection of a magnetic field rather than diffusion. Consequently, any planetary magnetic field which Venus may possess will be strongly affected by the global antisunward flow of the ionosphere which has been revealed by the Pioneer-Venus retarding potential analyzer. The magnetic flux from an internal magnetic field will accumulate in the night hemisphere. Details of the structure and dynamics of such accumulations depend on particular details of the magnetic field source and the time-dependent plasma flow pattern, but a simple interpretation of observational data yields a magnetic dipole moment of 7 x 10 to the 20th cu cm directed along the planet spin vector.

Knudsen, W. C.↗
NASA NTRS1994

Analysis of magnetic field data from Pioneer Venus orbiter

The subject grant (NAG 2-501) supported the analysis of magnetic field data from the Pioneer Venus orbiter for the period 10/1/87 to 9/30/94. During that period, 188 papers were contributed to scientific meetings that either analyzed the magnetometer data or used the data as part of the analysis of a scientific problem. Further, 107 papers were published in research journals and books. The magnetic moment of Venus was described. Venus was found to be essentially devoid of any intrinsic magnetic field. There was evidence though for the presence of lightning in the Venus atmosphere. The altitude distribution of impulsive signals in the night atmosphere was mapped and geographic clusters were found, most probably associated with local time ordering. A new means to create flux ropes in the ionosphere was postulated. On the nightside, ionospheric holes, ionospheric clouds, and tail rays were studied. The subsolar ionopause and the magnetic barrier were examined as was the altitude asymmetry of the ionopause, properties of the magnetosheath, and location of the bow shock upstream waves.

Russell, Christopher T.↗
NASA NTRS1993

Plasmasphere dynamics in the duskside bulge region: A new look at old topic

Data acquired during several multiday periods in 1982 at ground stations Siple, Halley, and Kerguelen and on satellites Dynamics Explorer 1, International Sun Earth Explorer 1, and GEOS 2 have been used to investigate thermal plasma structure and dynamics in the duskside plasmasphere bulge region of the Earth. The distribution of thermal plasma in the dusk bulge sector is difficult to describe realistically, in part because of the time integral manner in which the thermal plasma distribution depends upon on the effects of bulk cross-B flow and interchange plasma flows along B. While relatively simple MHD models can be useful for qualitatively predicting certain effects of enhanced convection on a quiet plasmasphere, such as an initial sunward entrainment of the outer regions, they are of limited value in predicting the duskside thermal plasma structures that are observed. Furthermore, use of such models can be misleading if one fails to realize that they do not address the question of the formation of the steep plasmapause profile or provide for a possible role of instabilities or other irreversible processes in plasmapause formation. Our specific findings, which are based both upon the present case studies and upon earlier work, include the following: (1) during active periods the plasmasphere appears to become divided into two entities, a main plasmasphere and a duskside bulge region. (2) in the aftermath of an increase in convection activity, the main plasmasphere tends (from a statistical point of view) to become roughly circular in equatorial cross section, with only a slight bulge at dusk; (3) the abrupt westward edge of the duskside bulge observed from whistlers represents a state in the evolution of sunward extending streamers; (4) in the aftermath of a weak magnetic storm, 10 to 30% of the plasma 'removed' from the outer plasmasphere appears to remain in the afternoon-dusk sector beyond the main plasmasphere. (5) outlying dense plasma structures may circulate in the outer duskside magetosphere for many days following an increase in convection, unless there is extremely deep quieting; (6) a day-night plasmatrough boundary may be identified in equatorial satellite data; (7) factor-of-2-to-10 density irregularities appear near the plasmatrough from the ionosphere at L = 4.6, predominantly bidirectional field aligned and equatorially trapped light ion pitch angle distributions give away to a predominantly isotropic distribution (as seen by DE 1) when the plasma density reaches a level a factor of about 3 below the satured plasmasphere level; (9) some outlying dense plasma structures are effectively detached from the main plasmasphere, while others appear to be connected to that body.

Carpenter, D. L.↗
NASA NTRS1972

6300 A quantum efficiency of the recombination mechanism in the night-time F layer.

Simultaneous airglow and electron content measurements made at Hawaii are used to infer the number of 6300 and 6364 A quanta produced per electron lost in the nighttime F layer of the ionosphere. The equation of continuity of electrons is then solved numerically to obtain the electron density profile, and the amount of quenching is estimated. This leads to the number of excitations of O(super-1 D) per O2(+) recombination (epsilon). We find, for an exospheric temperature of 1100 K, epsilon is equal to 1.1 plus or minus 0.6, in good agreement with Zipf's laboratory measurement at 300 K.

Brown, W. E.↗
NASA NTRS1993

Effect of sudden solar wind dynamic pressure changes at subauroral latitudes - Change in magnetic field

The observations obtained during the International Magnetospheric Study (IMS) from the magnetometers of the IGS network extending from Cambridge, England, to Tromso, Norway, are used to study the response of subauroral current systems to sudden changes in solar wind dynamic pressure. Observations show that the response is very strong at subauroral latitudes. The preliminary response in the H component is a brief, small increase in the dayside morning sector and a decrease in the aftenoon and night sectors. The main response in the horizontal field (the H and D components) is toward the pole except in the dayside morning sector. The inferred ionospheric current is mainly a circulatory system flowing counterclockwise when viewed from the north pole everywhere at subauroral latitudes except the dayside morning sector.

Le, G.↗
NASA NTRS1983

Basic theory and model calculations of the Venus ionosphere

An assessment is undertaken of current understanding of the physical and chemical processes that control Venus's ionospheric behavior, in view of the data that has been made available by the Venera and Pioneer Venus missions. Attention is given to the theoretical framework used in general planetary ionosphere studies, especially to the equations describing the controlling physical and chemical processes, and to the current status of the ion composition, density and thermal structure models developed to reproduce observed ionospheric behavior. No truly comprehensive and successful model of the nightside ionosphere has been published. Furthermore, although dayside energy balance calculations yield electron and ion temperature values that are in close agreement with measured values, the energetics of the night side eludes understanding.

Nagy, A. F.↗
NASA NTRS1987

Meteor matter interaction with the Earth's atmosphere and the ionospheric E-region structure

The exploration of the ionospheric E region is a pressing problem, both in the applied and fundamental studies. Results are presented of an investigation: (1) to estimate the meteor ionization contribution to the night time E layer and influx; (2) to study the phenomenon of intensive sporadic layer formation following cessation of meteor stream activity; and (3) to access the role of metallic ions of meteor origin in the diurnal and seasonal variations in the occurrence probabilities of midlatitude E sub s. The contribution was evaluated of meteor matter, Lyman radiation and corpuscular particles to the electron concentration of the night E region. Results are discussed.

Alimov, O.↗
NASA NTRS1972

Direct measurements of plasma drift velocities at high magnetic latitudes.

Description of an incoherent scatter radar experiment performed at the 23-cm radar facility in Chatanika, Alaska. The experiment has provided a direct method for measuring the ionospheric plasma transport velocity vector over long periods with relatively good time resolution. Since the F-region transport at this site is closely associated with magnetospheric convection, particularly at night, the radar can provide important information about the behavior of the magnetosphere.

Doupnik, J. R.↗
NASA NTRS1980

Global observations of the composition and dynamics of the ionosphere of Venus - Implications for the solar wind interaction

The in-situ measurements of the global composition and Venus ionosphere dynamics recorded by the Bennett ion mass spectrometer on the Pioneer Venus orbiter during Dec. 1978-Aug. 1979 are presented. The observations of three plasma regimes show the bowshock-ionosheath region, the thermal ionosphere, and a superthermal flowing ion layer contacting the ionosphere at the ionopause and extending outward to different heights above the planet. An abundant ionosphere dominated by O(+) above 200 km and by O2(+) down to the typical periapsis altitudes of 160 km occur during quiet periods; less disturbed data shows strong day to night changes in the distributions of ions including O(+), O2(+), CO2(+), and N(+). The ionopause is located near the subpolar point at 250-400 km; under disturbed nighttime conditions it may have randomly spaced concentration gradients in the dusk region.

Taylor, H. A., Jr.↗
NASA NTRS2022

La Soufriere Volcanic Eruptions Launched Gravity Waves Into Space

Atmospheric gravity waves can be excited by explosive volcanic eruptions and may reach Earth's upper atmosphere. In this study, we report on mesoscale concentric gravity waves observed in the mesopause airglow layer following the La Soufriere volcano eruption in April 2021. A large ash plume observed by the spaceborne Multi-angle Imaging SpectroRadiometer instrument on April 10 reached ∼20 km. Temporal evolution of the volcanic ash plume was provided by the GOES-16 Advanced Baseline Imager. Nightglow gravity waves were observed by the Visible Infrared Imaging Radiometer Suite Day Night Band. These waves had horizontal wavelengths of ∼25–40 km, and took about a half-to-1 hr to travel from the tropopause to the mesopause. Some concentric ionospheric disturbance signatures are also seen in Global Navigation Satellite System-total electron content maps. We found the launch of gravity waves to be highly correlated with the elevated ash plume from explosive eruptions.

gravity waves↗
NASA NTRS1971

The harang discontinuity in auroral belt ionospheric currents

Observations are compared to the Harang discontinuity to illustrate the reality and form of the discontinuity near midnight. High latitude magnetic disturbances and auroral displays were not found to be completely identical on any two days. The typical diurnal behavior during the night hours between 60 and 70 deg magnetic latitude was illustrated, using two patterns. Convection, time variablity, and current continuity of the Harang discontinuity are considered.

Herpner, J. P.↗
NASA NTRS1999

Rocket/Radar Sporadic-E Experiment Conducted during the El Coqui 2 Campaign

In order to investigate the complex electrodynamics and neutral-plasma coupling inherent to sporadic-E layers in the earth's mid-latitude ionosphere, a series of rocket/radar experiments were planned as part of the NASA El Coqui H Campaign from Tortuguero Launch Range, Puerto Rico, in March-April, 1998. The rocket experiments consisted of two pairs of "mother-daughter" payloads with limited apogees so that the payloads "hovered" in the sporadic-E region (95-125 km). Each payload pair included vector DC and AC electric field detectors, a highly accurate flux-gate DC magnetometer, an ion mass spectrometer, an ionization gauge, and spaced-electric field receivers to measure the wavelength and phase velocity of the unstable plasma waves. Separate rockets were included to simultaneously carry aloft TMA trails to measure the neutral wind and its velocity shear, believed responsible for the sporadic-E layer formation. In addition to the rocket experiments, incoherent scatter radar measurements of plasma density and drift velocity were gathered almost every night during the 3 week campaign. Continuous VHF backscatter radar operations were carried out from a site near Salinas, Puerto Rico, where 3-m backscatter echoes were observed associated with sporadic-E and other types of low altitude ionospheric layers. Other radars that operated during the campaign included an HF backscatter system near Ponce, Puerto Rico, and a second VHF backscatter radar set up near Aguadila Puerto Rico. On 24 March 1998, one of the instrumented rockets was launched, attaining an apogee of 129 km. The payloads successfully pierced an intense sporadic-E layer observed by both the Arecibo radar and the in-situ density and ion mass spectrometer probes. In-situ DC electric fields revealed very low (about 1-2 mV/m) ambient fields with small amplitude structures of the same order. No high frequency (short scale) waves were observed, consistent with the VHF backscatter observations at the time of the launch. An overview of the observations will be presented.

Pfaff, R.F.↗
NASA NTRS1990

A model of FTE footprints in the polar cap

The present investigation of the mapping of flux-transfer events (FTEs) onto the polar cap using the Toffoletto and Hill (1989) open version of Voigt's (1981) closed magnetic field model assumes that the magnetic flux associated with FTEs crosses the magnetopause through small regions of large normal components, whence these small flux tubes proceed to map to the polar cap ionosphere. It is found that while the footprint of a circular hole in the magnetopause of an otherwise closed magnetosphere becomes progressively distorted as the hole moves from the day to the night side, a similar region of enhanced open flux in an otherwise open magnetosphere retains an approximately circular footprint. Such regions, moving through the magnetosphere at a slower rate than the background, would generate the dipolar-electric field and current structures predicted by Southwood (1987).

Toffoletto, F. R.↗