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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Thermal coupling of conjugate ionospheres and the tilt of the earth's magnetic field

The effect of thermal coupling and the tilt of the earth's magnetic field on interhemispheric coupling is investigated, and, due to a longitudinal displacement in the conjugate points, it is found that the tilt significantly effects the upward flow of H(+) flux such that the maximum upward flux can occur several hours before local sunrise. Heating from the conjugate atmosphere, which accompanies solar illumination in one hemisphere, produces electron temperatures 1000 K higher in the dark than in the sunlit hemisphere, and the morning upward H(+) fluxes in the dark ionosphere are as large as the daytime fluxes. A strong symmetry is also noted in the overall behavior of the H(+) fluxes due to the differing day lengths at the conjugate points, which are separated by 15 deg in latitude. Electron temperatures in the conjugate hemispheres are found to be strongly coupled above the F region peaks, though in the vicinity of the peaks near 250 km, the coupling is weak during the day and strong during the night.

Richards, P. G.↗
NASA NTRS1976

Io sheath-accelerated electrons and ions

Recent results available from more rigorously analyzed Pioneer 10 data and the preliminary results of Pioneer 11 are used to further revise the satellite Io sheath acceleration model. The revised model is then employed to suggest an explanation for a number of earth-based and Pioneer 10 and 11 observations and to discuss other phenomena which might be detectable with future experiments. Particle acceleration near Io is discussed for the cases of negative sheath (face toward Jupiter) and positive sheath (face away from Jupiter). Io sputtering may explain the presence of atomic hydrogen and sodium in the vicinity of Io, and the accelerated particles may be important to the formation of the Io ionosphere. Directed fluxes of 100-keV electrons in the flux tube may lead to the decametric radio emissions, Jovian atmospheric heating, and optical and X ray emissions. Satellite modulation of decametric radio emissions is discussed.

Shawhan, S. D.↗
NASA NTRS1987

The precipitation of energetic heavy ions into the upper atmosphere of Jupiter

Evidence for auroral particle precipitation at Jupiter was provided by the ultraviolet spectrometers onboard the Voyagers 1 and 2 spacecraft and by the International Ultraviolet Explorer (IUE). Magnetospheric measurements made by instruments onboard the Voyager spacecraft show that energetic sulfur and oxygen ions are precipitating into the upper atmosphere of Jupiter. A theoretical model has been constructed describing the interaction of precipitating oxygen with the Jovian atmosphere. The auroral energy is deposited in the atmosphere by means of ionization, excitation, and dissociation and heating of the atmospheric gas. Energetic ion and electron precipitation are shown to have similar effects on the atmosphere and ionosphere of Jupiter.

Horanyi, M.↗
NASA NTRS1993

The effects on the ionosphere of inertia in the high latitude neutral thermosphere

High-latitude ionospheric currents, plasma temperatures, densities, and composition are all affected by the time-dependent response of the neutral thermosphere to ion drag and Joule heating through a variety of complex feedback processes. These processes can best be studied numerically using the appropriate nonlinear numerical modeling techniques in conjunction with experimental case studies. In particular, the basic physics of these processes can be understood using a model, and these concepts can then be applied to more complex realistic situations by developing the appropriate simulations of real events. Finally, these model results can be compared with satellite-derived data from the thermosphere. We used numerical simulations from the National Center of Atmospheric Research Thermosphere/Ionosphere General Circulation Model (NCAR TIGCM) and data from the Dynamic Explorer 2 (DE 2) satellite to study the time-dependent effects of the inertia of the neutral thermosphere on ionospheric currents, plasma temperatures, densities, and composition. One particular case of these inertial effects is the so-called 'fly-wheel effect'. This effect occurs when the neutral gas, that has been spun-up by the large ionospheric winds associated with a geomagnetic storm, moves faster than the ions in the period after the end of the main phase of the storm. In these circumstances, the neutral gas can drag the ions along with them. It is this last effect, which is described in the next section, that we have studied under this grant.

Burns, Alan↗
NASA NTRS1984

Assessment of Plasma Transport and Convection at High Latitudes

The high-latitude ionosphere is strongly coupled to the thermosphere and magnetosphere. The magnetospheric coupling occurs via electric fields, field-aligned currents, and particle precipitation. Owing to the interaction of the shocked solar wind with the geomagnetic field, an electric potential difference is generated across the tail of the magnetosphere, with the resulting electric field pointing from dawn to dusk. Energetic particle precipitation from the magnetosphere in the auroral region leads to the creation of ionization and to electron, ion, and neutral gas heating. In order to assess the current understanding of plasma transport and convection at high latitudes, it is necessary to take account of the strong coupling between the ionosphere, thermosphere, and magnetosphere.

Source record↗
NASA NTRS1992

Thermospheric heating away from the auroral oval during geomagnetic storms

The data on the morphology of the changes in the heating of thermosphere in the middle and high latitudes during geomagnetic storms, collected by the DE-2 satellite between July 1981 and February 1983 are compared with the NCAR-Thermosphere-Ionosphere General Circulation Model simulation of the November 24, 1982 storm on a one-on-one basis for an individual orbit in the middle of this storm. Good agreement was found for the winter hemisphere. A thermodynamic diagnostic processor was then used to investigate the mechanism by which geomagnetic storms cause temperature increases at lower latitudes. It was found that the pattern of heating during geomagnetic storms is complex, indicative of the complex nature of the physical processes that alter the thermal structure of the thermosphere at these times. Model predictions indicated that the greatest temperature increase at 40 deg N occurs in the morning, in agreement with results of Proelss (1984).

Burns, A. G.↗
NASA NTRS1981

The nature of the solar wind interaction with CO2/CO-dominated comets

The nature of the interaction of the solar wind with the ionospheres (field-free ion cavities) of comets with CO or CO2 as their dominant volatile species is considered and compared with the solar wind interaction with H2O-diominated comets. Calculations of the heliocentric variation of scale lengths defined as the nuclear distance at which the mean free path for ion-neutral collisions becomes equal to the nuclear distance, and the ion and neutral stand-off distances are presented for different modes of energy addition, nuclear radii and ionization time scales. Results indicate that whereas little activity can be expected from H2O-dominated comets at distances beyond 3 AU, COand CO2-dominated comets can be expected to be quite prolific at such distances. In contrast to H2O-dominated comets characterized by weak shocks, CO/CO2-dominated comet solar wind interactions are found to produce strong bow shocks within a specific heliocentric distance for the isothermal case of a CO-dominated comet, and a weak shock outside of this distance. In the general case, two types of cometary ionosphere transitions are found: a transition from strong to weak bow shock and from a compressible (soft) to an incompressible (hard) ionosphere, and a transition from a soft to a hard ionosphere with the bow shock remaining weak at a heliocentric distance dependant on atmospheric optical depth, bolometric albedo, nuclear radius, latent heat of sublimation of nuclear material, ionization time scale and type of heat addition. It is pointed out that the behavior of Comet Humason can be explained by solar wind interactions with a CO- or CO2-dominated comet.

Houpis, H. L. F.↗
NASA NTRS1987

Theoretical study of the effect of ionospheric return currents on the electron temperature

A time-dependent, three-dimensional model of the high-altitude ionosphere is presently used to study the effects of field-aligned ionospheric return currents on auroral electron temperatures for different seasonal and solar cycle conditions, as well as for different upper boundary heat fluxes. The average, large scale, return current densities, which are a few microamps/sq m, are too small to affect auroral electron temperatures. The thermoelectric effect exhibits a pronounced solar cycle and seasonal dependence, and its heat transport corresponds to an upward flow of electron energy which can be either a source or sink of electron energy depending on altitude and geophysical conditions.

Schunk, R. W.↗
NASA NTRS1988

The precipitation of energetic heavy ions into the upper atmosphere of Jupiter

Evidence for auroral particle precipitation at Jupiter was provided by the ultraviolet spectrometers on board the Voyager 1 and 2 spacecraft and by the International Ultraviolet Explorer. Magnetospheric measurements made by instruments on board the Voyager spacecraft indicate that energetic sulfur and oxygen ions are precipitating into the upper atmosphere of Jupiter. A theoretical model describing the interaction of precipitating oxygen with the Jovian atmosphere was constructed. The auroral energy is deposited in the atmosphere by means of ionization, excitation, and dissociation and heating of the atmospheric gas. Energetic ion precipitation and electron precipitation are shown to have similar effects on the atmosphere and ionosphere of Jupiter.

Horanyi, M.↗
NASA NTRS2022

Surface-to-Space Atmospheric Waves From Hunga Tonga–Hunga Ha’apai Eruption

The January 2022 Hunga Tonga–Hunga Ha’apai eruption was one of the most explosive volcanic events of the modern era, producing a vertical plume that peaked more than 50 km above the Earth. The initial explosion and subsequent plume triggered atmospheric waves that propagated around the world multiple times. A global-scale wave response of this magnitude from a single source has not previously been observed. Here we show the details of this response, using a comprehensive set of satellite and ground-based observations to quantify it from surface to ionosphere. A broad spectrum of waves was triggered by the initial explosion, including Lamb waves propagating at phase speeds of 318.2 ± 6 m s^(−1) at surface level and between 308 ± 5 to 319 ± 4 m s^(−1) in the stratosphere, and gravity waves propagating at 238 ± 3 to 269 ± 3 m s^(−1) in the stratosphere. Gravity waves at sub-ionospheric heights have not previously been observed propagating at this speed or over the whole Earth from a single source. Latent heat release from the plume remained the most significant individual gravity wave source worldwide for more than 12 h, producing circular wavefronts visible across the Pacific basin in satellite observations. A single source dominating such a large region is also unique in the observational record. The Hunga Tonga eruption represents a key natural experiment in how the atmosphere responds to a sudden point-source-driven state change, which will be of use for improving weather and climate models.

Corwin J. Wright↗
NASA NTRS1991

Effects of large zonal plasma drifts on the subauroral ionosphere

A model of the earth's ionosphere and plasmasphere is used to investigate the effects of an imposed westward plasma drift of maximum velocity 2 km/s. A closed subauroral tube of plasma is considered and the velocity spike persists for 10 min. Ion-neutral frictional heating causes rapid elevation of the F-region O(+) temperature. The F-layer O(+) concentration is decreased due to increased O(+) loss rate and rapid ion flows both upward and downward from the F-region. The upward flux of O(+) through the topside ionosphere can each 5 x 10 exp 9/sq cm/s; when the velocity spike ceases there is a return flow of O(+) that tends to replenish the F-layer. Most of the features revealed by the model for the F-region and topside ionosphere are in accord with observations of subauroral ion drifts. Downward flows that are predicted to be persistently present around the 300 km altitude level appear to agree with observations only occasionally; suggestions are made to resolve this discrepancy.

Sellek, R.↗
NASA NTRS1990

Investigation of nonlinear E.M. phenomena in the tethered magnetospheric cloud

Nonlinear effects of parametric and of heating type, produced in a plasma under the action of an electric field E(sub 0)(e exp i(omega)t), are considered in this work in connection with the Tethered Magnetospheric Cloud (TMC) accompanying the Tether Satellite System (TSS). The theoretical results show that these phenomena should appear in the ionosphere at high altitudes Z greater than or = (150-200) km, particularly, at Z approximately = 300 km of the TSS system orbit. Therefore, it is of a special interest to search these phenomena by such a unique experiment as the forthcoming first TSS-I and by the future, perhaps modified TSS missions. Because of the parametric decay instability, new branches of wave may be excited both around the electron and ion Lengmuir frequencies Omega (sub 0) = 2(pi)f(sub 0) and Omega (sub 0) = 2(pi)f(sub 0) under the influence of high frequency (HF), (f less than or = 10(exp 6) to few 10(exp 6) Hz), strong electric waves. The heating of all the kinds of particles is growing up very quickly in the ionosphere with altitude in the extra low and very low frequency ranges, F approximately = (1 to 10(exp 4) Hz, discussed below. The temperatures (energies), for example, of the electrons accelerated by the electric field become larger than the ionization potential in this frequency range already at altitudes Z greater than or = (150 - 200) km when the amplitude of the electric field is the absolute value of E(sub 0) approximately = (1-2) mV/m. The sources of these electric fields may be in the TSS-I mission, that so called Phantom Loop (PL) - the Tethered Electrodynamic Tail (TET), and the different kind of electromagnetic oscillations produced by different kinds of instabilities in the TMC plasma. The growth rates of these instabilities will become very high in the TSS surrounding magnetoplasma. However, in the future TSS missions, special artificial sources (generators) of electric fields should be used for these investigations.

Alpert, Yakov L.↗
NASA NTRS2005

Integrated Modeling Study of the Effects of the Magnetospheric Forcing on the Jovian Ionosphere-Thermosphere System

The Jupiter Thermosphere General Circulation Model (JTGCM) calculates the global dynamical structure of Jupiter s thermosphere self-consistently with its global thermal structure and composition. The main heat source that drives the thermospheric flow is high-latitude Joule heating. A secondary source of heating is the auroral process of particle precipitation. Global simulations of Jovian thermospheric dynamics indicate strong neutral outflows from the auroral ovals with velocities up to approx.2 km/s and subsequent convergence and downwelling at the Jovian equator. Such circulation is shown to be an important process for transporting significant amounts of auroral energy t o equatorial latitudes and for regulating the global heat budget in a manner consistent with the high thermospheric temperatures observed by the Galileo probe. Adiabatic compression of the neutral atmosphere resulting from downward motion is an important source of equatorial heating (< 0.06 microbar). The adiabatic heating continues to dominate between 0.06 and 0.2 microbar, but with an addition of comparable heating due to horizontal advection induced by the meridional flow. Thermal conduction plays an important role in transporting heat down to lower altitudes (>0.2microbar) where it is balanced by the cooling associated with the wind transport processes. Interestingly, we find that radiative cooling caused by H3(+), CH4, and C2H2 emissions does not play a significant role in interpreting the Galileo temperature profile.

Bogan, Denis↗
NASA NTRS1980

Solar Power Satellite Microwave Power Transmission System Description Executive Summary

The history of the concept of microwave power beaming to Earth is reviewed with emphasis on transmission frequency selection. Constraints on the system power level results from (1) required rejection of waste heat resulting from inefficiencies in the cover conversion of dc electric power to microwave power; (2) the rf power intensity in the ionosphere; and (3) the effect of sidelobe level on aperture illumination factors. Transmitter arrangement, the power distribution system, attitude control, subarrays, waveguides, and alignment are discussed.

Woodcock, G. R.↗
NASA NTRS1982

Energetic O/+/ precipitation

Fluxes of energetic O(+) ions are often observed precipitating into the atmosphere and are possibly a significant energy source for the ionosphere and thermosphere. Models of these events indicate that most of the energy of such an O(+) beam is deposited as neutral heat at F region heights and a significant escape flux of O atoms results. The distribution of this heating with altitude, however, has a major effect on the type and significance of the aeronomical consequences that it can initiate. The particulars of this distribution are very sensitive to the cross sections and scattering parameters used in the modeling. A comparison of hard sphere and classical elastic parameters indicates that using the latter, more realistic formulation not only results in a more penetrating beam but reduces the escape flux by as much as a factor of 2 over the hard sphere treatment.

Kozyra, J. U.↗
NASA NTRS1994

Auroral plasma transport processes in the presence of kV potential structures

We have simulated plasma transport processes in the presence of a quasi-two-dimensional current filament, that generated kV potential structure in the auroral region. The simulation consists of a set of one-dimensional flux tube simulations with different imposed time-dependent, field-aligned currents. The model uses the 16 moment system of equations and simultaneously solves coupled continuity and momentum equations and equations describing the transport along the magnetic field lines of parallel and perpendicular thermal energy and heat flows for each species. The lower end of the simulation is at an altitude of 800 km, in the collisional topside ionosphere, while the upper end is at 10 R(sub E) in the magnetosphere. The plasma consists of hot electrons and protons of magnetospheric origin and low-energy electrons, protons, and oxygen ions of ionospheric origin. The dynamical interaction of the individual current filaments with ionospheric and magnetospheric plasma generates a potential structure in the horizontal direction and kilovolt field-aligned potential drops along the field lines. The side-by-side display exhibits the evolution of the implied potential structure in the horizontial direction. In the presence of this potential structure and parallel electric field ionospheric plasma density is depleted and velocity is reduced, while density enhancement and increased velocity is observed in magnetospheric plasma. The ionospheric and magnetospheric electron temperatures increase below 2 R(sub E) due to magnetic mirror force on converging geomagnetic field lines. The primary cross-field motion produced by the horizontal E field (E x B drift) is perpendicular to both of the significant spatial directions and is thus ignorable in this geometry. The effects of other cross-field drift processes are discussed. The simulation thus provides insight into the dynamical evolution of two-dimensional potential structures driven by an imposed finite width, field-aligned current profile.

Ganguli, Supriya B.↗
NASA NTRS1995

Atmospheric response in aurora experiment: Observations of E and F region neutral winds in a region of postmidnight diffuse aurora

The goal of the Atmospheric Response in Aurora (ARIA) experiment carried out at Poker Flat, Alaska, on March 3, 1992, was to determine the response of the neutral atmosphere to the long-lived, large-scale forcing that is characteristic of the diffuse aurora in the post midnight sector. A combination of chemical release rocket wind measurements, instrumented rocket composition measurements, and ground-based optical measurements were used to characterize the response of the neutral atmosphere. The rocket measurements were made at the end of a 90-min period of strong Joule heating. We focus on the neutral wind measurements made with the rocket. The forcing was determined by running the assimilated mapping of ionospheric electrodynamics (AMIE) analysis procedure developed at the National Center for Atmospheric Research. The winds expected at the latitude and longitude of the experiment were calculated using the spectral thermospheric general circulation model developed at the Danish Meteorological Institute. Comparisons of the observations and the model suggest that the neutral winds responded strongly in two height ranges. An eastward wind perturbation of approximately 100 m/s developed between 140 and 200 km altitude with a peak near 160 km. A southwestward wind with peak magnitude of approximately 150 m/s developed near 115 km altitude. The large amplitude winds at the lower altitude are particularly surprising. They appear to be associated with the upward propagating semidiurnal tide. However, the amplitude is much larger than predicted by any of the tidal models, and the shear found just below the peak in the winds was nominally unstable with a Richardson number of approximately 0.08.

Larsen, M. F.↗
NASA NTRS2004

Global Dayside Ionospheric Uplift and Enhancement Associated with Interplanetary Electric Fields

The interplanetary shock/electric field event of 5-6 November 2001 is analyzed using ACE interplanetary data. The consequential ionospheric effects are studied using GPS receiver data from the CHAMP and SAC-C satellites and altimeter data from the TOPEX/ Poseidon satellite. Data from ~100 ground-based GPS receivers as well as Brazilian Digisonde and Pacific sector magnetometer data are also used. The dawn-to-dusk interplanetary electric field was initially ~33 mV/m just after the forward shock (IMF BZ = -48 nT) and later reached a peak value of ~54 mV/m 1 hour and 40 min later (BZ = -78 nT). The electric field was ~45 mV/m (BZ = -65 nT) 2 hours after the shock. This electric field generated a magnetic storm of intensity DST = -275 nT. The dayside satellite GPS receiver data plus ground-based GPS data indicate that the entire equatorial and midlatitude (up to +/-50(deg) magnetic latitude (MLAT)) dayside ionosphere was uplifted, significantly increasing the electron content (and densities) at altitudes greater than 430 km (CHAMP orbital altitude). This uplift peaked ~2 1/2 hours after the shock passage. The effect of the uplift on the ionospheric total electron content (TEC) lasted for 4 to 5 hours. Our hypothesis is that the interplanetary electric field ''promptly penetrated'' to the ionosphere, and the dayside plasma was convected (by E x B) to higher altitudes. Plasma upward transport/convergence led to a ~55-60% increase in equatorial ionospheric TEC to values above ~430 km (at 1930 LT). This transport/convergence plus photoionization of atmospheric neutrals at lower altitudes caused a 21% TEC increase in equatorial ionospheric TEC at ~1400 LT (from ground-based measurements). During the intense electric field interval, there was a sharp plasma ''shoulder'' detected at midlatitudes by the GPS receiver and altimeter satellites. This shoulder moves equatorward from -54(deg) to -37(deg) MLAT during the development of the main phase of the magnetic storm. We presume this to be an ionospheric signature of the plasmapause and its motion. The total TEC increase of this shoulder is ~80%. Part of this increase may be due to a "superfountain effect." The dayside ionospheric TEC above ~430 km decreased to values ~45% lower than quiet day values 7 to 9 hours after the beginning of the electric field event. The total equatorial ionospheric TEC decrease was ~16%. This decrease occurred both at midlatitudes and at the equator. We presume that thermospheric winds and neutral composition changes produced by the storm-time Joule heating, disturbance dynamo electric fields, and electric fields at auroral and subauroral latitudes are responsible for these decreases.

ionosphere↗