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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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NASA NTRS1981

ISEE-1 observations of electrostatic shocks on auroral zone field lines between 2.5 and 7 earth radii

The ISEE-1 satellite frequently passes through electrostatic shocks and the low altitude auroral particle acceleration region at geocentric radial distances less than approximately 7 earth radii and as low as greater than or equal to 2 earth radii. A sampling of data from the quasi-static electric field experiment during 22 such passes revealed events (defined as regions of low frequency turbulence) containing electrostatic shocks (defined as an electric field greater than or equal to 100 mV/m) during eight of the passes, which is an occurrence frequency comparable to that obtained near apogee on the S3-3 satellite. Examination of three such electrostatic shocks shows that typical potentials of a few kV and latitudinal scale widths mapped to the ionosphere of a few km are encountered. From the latitudinal widths of the shocks and from the magnitudes of their observed electric fields, it is argued that the parallel electric field and auroral particle acceleration region may be confined to geocentric distances less than a few earth radii.

Mozer, F. S.↗
NASA NTRS1981

The 1966 observations of the coorbiting satellites of Saturn, S10 and S11

Most of the positions of faint satellite images obtained during the 1966 Saturn ring plane crossing fit the period of the coorbital satellites 1980 S1 and 1980 S3. In 1966 the satellites were separated by 137 deg in orbital longitude. Until the mutual interaction of the satellites is understood and applied to derive the precise orbital motion, the 1966 and 1980 observations cannot be linked.

Larson, S. M.↗
NASA NTRS1981

The small-scale structure of electrostatic shocks

It is noted that small-scale regions of large electric fields have been observed above the auroral zone by the S3-3 satellite. The data from five such electrostatic shocks are examined in great detail. The three higher altitude shocks (all above 5,700 km) are found to be associated with upward-going ion beams, indicating that the potential associated with the shock closed below the satellite to give rise to the parallel electric field required for the acceleration of the ion beam. In all these cases, electrostatic ion cyclotron waves are found to be adjacent to the shock and to extend throughout the upward-going ion beam region. The lack of noticeable Doppler shift in the electrostatic ion cyclotron waves in association with large convective drift velocities is seen as indicating that the wavelength of the electrostatic ion cyclotron wave can be several kilometers and that the potential difference within the wave can be on the order of 100 V.

Temerin, M.↗
NASA NTRS1982

Modeling of high-latitude currents in a substorm

The currents and electric fields in the area covered by the poleward set of field-aligned currents are computed by means of a quantitative model, in which the high-latitude band considered carries most of the poleward electrojet, and lies poleward of the region covering the inner magnetosphere and corresponding ionosphere. The Birkeland current and aurorally enhanced conductivity are assumed to be uniformly distributed across the band. The time-dependent conductivity model used is based on electron fluxes and mean energies measured from the S3-2 satellite. Joule heating of the upper atmosphere was found to be about 2 x 10 to the 11th W during the substorm period. Model values for the strength of the electrojet and the amount of Joule heating agree to within about 20% with results based on a simple Cowling conductivity band.

Karty, J. L.↗
NASA NTRS1981

Mechanisms for intense relativistic electron precipitation

An analysis of data gathered over a period of 14 months by the S3-3 satellite has revealed the detection of 313 relativistic electron precipitation events with isotropic flux over the upward-looking hemisphere, of which the majority occur at night in a narrow latitudinal zone which is embedded within a broader region of intense energetic ion precipitation. Three classes of precipitation are found to be associated with strong, diffusion resonant scattering due to known magnetospheric plasma waves. It is also found that intense electron energy deposition is a major source of middle-atmospheric, odd-hydrogen and odd-nitrogen molecules at sub-auroral latitudes, leading to an observable catalytic destruction of mesospheric ozone.

Thorne, R. M.↗
NASA NTRS1982

The Seasat altimeter mean sea surface model

Gridding techniques are used to combine an 18-day set of Seasat altimeter data and two precisely-computed Seasat ephemerides, in order to arrive at global contour maps of the mean sea surface topography. The altimeter data have an rms agreement of 111 cm with the SS3 mean sea surface computed by means of the PGS-S3 ephemerides, and of 70 cm with the SS4 mean surface derived from the PGS-S4 ephemerides. While comparisons with the GEM 10B 1 x 1 deg gravimetric geoid have yielded rms differences of 2.8 m, those with a global mean sea surface derived from GEOS 3 altimeter data show rms differences of 1.3 m and 1.1 m for the cases of the SS3 and SS4 surfaces, respectively. An SS4 mean sea surface topograph is featured among the study findings presented. Further improvements in the representation of mean sea surface topography are expected with the development of more accurate gravity models for orbit computation.

Marsh, J. G.↗
NASA NTRS1982

Growth rate calculations of auroral kilometric radiation using the relativistic resonance condition

The relativistic cyclotron resonance condition for right-handed extraordinary mode waves defines an ellipse in velocity space. The position of the center and size of the semiminor axis of this ellipse are functions of the plasma frequency, gyrofrequency, wave frequency, and wave normal angle. The effect of varying these parameters on the position and size of the resonance contour is analyzed. The results show that as the wave normal angle decreases, the semiminor axis increases in size and as the plasma frequency to gyrofrequency ratio decreases, the minimum energy for resonating electrons decreases and the maximum wave normal angle allowed by the resonance condition increases. Also, as the wave frequency to gyrofrequency ratio increases, the center of the resonance ellipse moves away from the origin. The relativistic resonance condition and the electron distribution in velocity space obtained by the S3-3 satellite are used to calculate numerically growth rates for the terrestrial auroral kilometric radiation. It is shown that the loss cone region of the electron distribution can give rise to growth rates for the extraordinary mode that are sufficiently large to account for the observed radio emission intensities.

Omidi, N.↗
NASA NTRS1982

Generation of the auroral kilometric radiation

Data collected from the S3-3 spacecraft in the auroral kilometric radiation (AKR) source region are employed to form a stability theory from which numerical results are obtained and discussed. The distribution function was found to be isotropic outside the auroral atmospheric loss-cone region, which was partially filled with upcoming electrons. A parallel electric field was observed to be modifying the loss-cone distribution. A model distribution function is formulated, along with a magnetic field model expressed in terms of the electron cyclotron frequency. Models for the parallel electric field are also introduced, the first with the field distributed over a broad altitude range, while the second assumes a potential drop only above 4000 km. The presence of the field is found to enhance the growth rate of the AKR. At higher altitudes, the cutoff frequency of the X mode is affected by the rising energetic electrons. Finally, the folding distances of spatial amplification are calculated.

Wu, C. S.↗
NASA NTRS1982

Flute mode waves near the lower hybrid frequency excited by ion rings in velocity space

Discrete emissions at the lower hybrid frequency are often seen on the S3-3 satellite. Simultaneous observation of perpendicularly heated ions suggests that these ions may provide the free energy necessary to drive the instability. Studies of the dispersion relation for flute modes excited by warm ion rings in velocity space show that waves are excited with real frequencies near the lower hybrid frequency and with growth rates ranging from about 0.01 to 1 times the ion cyclotron frequency. Numerical results are therefore consistent with the possibility that the observed ions are the free energy source for the observed waves.

Cattell, C.↗
NASA NTRS1982

Current-driven double layers and the auroral plasma

Simulation results on current-driven double layers are presented. The role of the Buneman instability in the formation of double layers is clearly identified. The recurring formation and motion of double layers produce a temporal variation of the electric fields similar to that observed in the auroral plasma by the S3-3 satellite.

Singh, N.↗
NASA NTRS1983

Theory of motion of Saturn's coorbiting satellites

A simple analytic theory describing the 1:1 orbital resonance is presented and applied to Saturn's coorbiting pair, 1980S1 and 1980S3. These satellites are very small and can approach to within 15,000 km, but are prevented from passing each other by their mutual gravitational interaction. The long-term stability of the S1-S3 orbital configuration is discussed in this paper, and a tie between the 1966 and 1980 observations is established.

Yoder, C. F.↗
NASA NTRS1983

Preferential perpendicular acceleration of heavy ionospheric ions by interactions with electrostatic hydrogen cyclotron waves

Observations in recent years indicate the presence of energetic ions of ionospheric origin in various parts of the magnetosphere. These energetic ions have been found at all latitudes. Observations from the S3-3 satellite have made a great contribution toward an understanding of the energization of ionospheric ions. One of the most interesting observations is related to the finding that ion beams and electrostatic hydrogen cyclotron (EHC) waves are highly correlated and that they show an abrupt increase in their occurrence rate at an altitude of about 5000 km. A statistical survey of upward flowing ion (UFI) events occurring between 6000 and 8000 km has shown that the average energy of O(+) has a strong correlation with that of the H(+) ions. The present investigation has the objective to examine critically the energetics of UFI events in view of the theory of the interaction of a single coherent EHC wave with O(+), He(+), and H(+) ions. It is found that preferential acceleration of heavy ions occurs when such ions interact with an EHC wave.

Singh, N.↗
NASA NTRS1983

Energy transfer in the quiet and disturbed magnetosphere

Progress on magnetospheric energy transfer reported during the 1979-1982 quadrennium is reviewed. A discussion of the macroscopic control of magnetospheric phenomena by solar-wind electric and magnetic fields and kinetic pressure is followed by sections on energy transfer processes at the dayside magnetopause, in the magnetotail, near geosynchronous orbit, and at altitudes of about 1 earth radius above the auroral oval. Rapid progress in these areas has been stimulated primarily by ISEE and S3-3 observations and by the development of techniques for the large-scale computer simulation of plasma phenomena.

Burch, J. L.↗
NASA NTRS1984

Solar influence on terrestrial weather and global lightning patterns via cosmic ray modulations

A series of cosmic ray neutron monitor data which were used in three analyses: (1) solar activity influence on ionization of the upper troposphere and tropopause; (2) solar activity influence on Canadian high stratus in winter; and (3) the S3-4 satellite study of IMF/GMF magnetic coupling effects are reported. The magnetic coupling model of solar activity influence on atmospheric processes were investigated. The magnetic coupling model is used to explain a number of seemingly diverse studies lightning incidence is emphasized.

Ely, J. T. A.↗
NASA NTRS1984

Electrostatic ion (hydrogen) cyclotron and ion acoustic wave instabilities in regions of upward field-aligned current and upward ion beams

An investigation is made into the stability of electrostatic hydrogen ion cyclotron and ion acoustic waves in a model plasma where an ion beam, population 2, and oppositely directed drifting electrons pass through a stationary ion background, population 1. The excited wave properties are then compared with the characteristics of the unstable modes observed on the S3-3 satellite. Three temperature regimes are studied: (1) Te greater than Ti2 much greater than Ti1, (2) Ti2 greater than Te not less than Ti1, and (3) Te approximately equal to Ti1 greater than Ti2. It is found that the ion beam acts as a free energy source only in regime 1. This regime is also highly unstable to the electrons as a free energy source. Unstable modes in regimes 2 and 3 seem to best satisfy the electrostatic hydrogen cyclotron wave (EHC) properties at 1 earth radius. For these cases the electrons are the free energy source, the beam supplies damping.

Bergmann, R.↗
NASA NTRS1983

Further analysis of a recent cosmic-ray antiproton experiment

Reference is made to the measurements of a cosmic ray antiproton flux at a few hundred MeV reported by Buffington et al. (1981), noting that one of the final background processes to be removed by the data analysis in that study was helium-induced events which satisfied the criteria for topology and timing. The response in the third scintillator S3 was used to identify and remove these events. For the top two scintillators S1 and S2, pulse size information was lost during the data-taking. A method is reported here for the partial retrieval of pulse size information for the scintillator S2. This is possible because a portion of this signal was subtracted from the Cerenkov response before trigger discrimination and data recording to remove scintillation from the Cerenkov response. For separating protons from more highly charged particles, the method is considered sufficient. It is pointed out that the sample of events identified as antiprotons, for which the method can be applied, has the expected unit charge in scintillator S2.

Buffington, A.↗
NASA NTRS1984

Electrostatic hydrogen-cyclotron wave emission below the hydrogen-cyclotron frequency in the auroral acceleration region

A mechanism is suggested for the excitation of electrostatic ion-cyclotron waves at frequencies below the ion-cyclotron frequency in the midst of the auroral acceleration region, which is assumed to consist of downward moving double layers. The mechanism involves upward flowing ions interacting with a downward flowing background plasma. The upward flowing ions are the ion beams accelerated by the double layer. The downward motion of the background plasma corresponds to a plasma expansion into the density cavity that develops in connection with double layer formation in the acceleration region. The ion-cyclotron waves excited by the counterstreaming flows are doppler shifted to frequencies below the harmonics of the ion cyclotron frequency. It is suggested that such wave emissions could account for some very narrow-banded waves at frequencies below the hydrogen cyclotron frequency that were observed by the S3-3 satellite.

Singh, N.↗
NASA NTRS1984

Electromagnetic ion cyclotron mode (ELF) waves generated by auroral electron precipitation

Narrow-banded ELF waves with frequencies between the local hydrogen and the singly-charged helium gyrofrequencies have been seen in the S3-3 satellite electric field wave data at altitudes between 800 and 8000 km. The waves are generated in or just below the auroral acceleration region by the accelerated electron beam and propagate in the Alfven-ion cyclotron branch of the cold electromagnetic dispersion relation as modified by the presence of a two ion H(+)-He(+) plasma.

Temerin, M.↗