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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Properties of AKR from an interferometer analysis of the ISEE-1 and -2 plasma wave data

Both ISEE 1 and 2 are equipped with identical wide-band analog plasma wave receivers which makes long baseline interferometry possible. A cross-correlation of the received signals from each spacecraft during periods of intense Auroral Kilometric Radiation (AKR) provides information on the source size of AKR. From the magnitude of the cross-correlation coefficient, measured over baselines from 40 Km to 8000 Km, an upper limit to the statistical source size can be determined. Thirty-five AKR events at 125 kHz are being analyzed. Preliminary results indicate that the apparent source sizes are smaller than .1 Re.

Baumback, M. M.↗
NASA NTRS1982

Data reduction and analysis of ISEE magnetometer experiment

The ISEE-1 and -2 magnetometer data was reduced. The up and downstream turbulence associated with interplanetary shocks were studied, including methods of determining shock normals, and the similarities and differences in laminar and quasi-laminar shock structure. The associated up and downstream turbulence was emphasized. The distributions of flux transfer events, field aligned currents in the near tail, and substorm dynamics in the magnetotail were also investigated.

Russell, C. T.↗
NASA NTRS1982

Plasma wave experiment for the ISEE-3 mission

Analysis of data from a scientific instrument designed to study solar wind and plasma wave phenomena on the ISEE-3 mission is presented. The performance of work on the data analysis phase is summarized.

Scarf, F. L.↗
NASA NTRS1982

Plasma properties of driver gas following interplanetary shocks observed by ISEE-3

Plasma fluid parameters calculated from solar wind and magnetic field data obtained on ISEE 3 were studied. The characteristic properties of driver gas following interplanetary shocks was determined. Of 54 shocks observed from August 1978 to February 1980, nine contained a well defined driver gas that was clearly identifiable by a discontinuous decrease in the average proton temperature across a tangential discontinuity. While helium enhancements were present in all of nine of these events, only about half of them contained simultaneous changes in the two quantities. Often the He/H ratio changed over a period of minutes. Simultaneous with the drop in proton temperature the helium and electron temperature decreased abruptly. In some cases the proton temperature depression was accompanied by a moderate increase in magnetic field magnitude with an unusually low variance and by an increase in the ratio of parallel to perpendicular temperature. The drive gas usually displayed a bidirectional flow of suprathermal solar wind electrons at higher energies.

Zwickl, R. D.↗
NASA NTRS1983

Plasma wave experiment for the ISEE-3 mission

An analysis of data from a scientific instrument designed to study solar wind and plasma wave phenomena on the ISEE-3 Mission is provided. Work on the data analysis phase of the contract from 1 October 1982 through 30 March 1983 is summarized.

Scarf, F. L.↗
NASA NTRS1983

Science return from ISEE-3 at comet Giacobini-Zinner

The spacecraft ISEE-3 will be sent to encounter the Giacobini-Zinner comet in September 1985 during the period of intense Halley observations. This mission provides a unique opportunity for comparative study of important dynamical processes at both short and long term comets.

Scarf, F. L.↗
NASA NTRS1982

An electric noise component with density 1/f identified on ISEE 3

The properties of the 1/f noise detected at the terminals of ISEE 3 antennas are described and related to the solar wind parameters. The 1/f noise was observed with the radio receivers of the three-dimensional radio mapping experiment using the S and Z dipole antennas. The noise spectra contained a negative spectral index component at frequencies lower than 0.7 of the plasma frequency, and 5-10 times the predicted thermal noise for the Z antenna. S-antenna measurements of the 1/f component revealed it to be deeply spin modulated with a minimum electric field in the direction of the solar wind. Modulation increases with increasing frequency, becomes negligible when the 1/f intensity is negligible with respect to the thermal noise, and increases with solar wind velocity. The possibilities that the noise is due either to waves or currents are discussed.

Hoang, S.↗
NASA NTRS1983

Plasma rest frame frequencies and polarizations of the low-frequency upstream waves - ISEE 1 and 2 observations

The plasma rest frame frequencies and polarizations of the large amplitude low frequency (0.03 Hz) upstream waves are investigated using magnetic field data from the dual ISEE 1 and 2 spacecraft. The monochromatic sinusoidal waves associated with intermediate ion fluxes are propagating in both the Alfven and magnetosonic modes, in both cases with typical frequencies approximately 0.1 times the local proton gyrofrequency and wavelengths of approximately 1 R(E). It is shown that the generation of the magnetosonic mode can be explained by the cyclotron resonance mechanism driven by narrow reflected ion beams, but the concurrent observation of Alfven mode waves appears to require wave generation by the more isotropic diffuse ion distributions as well.

Hoppe, M. M.↗
NASA NTRS1983

Solar wind deceleration and MHD turbulence in the earth's foreshock region - ISEE 1 and 2 and IMP 8 observations

The interaction of the solar wind with ions backstreaming from the earth's bow shock is investigated using plasma and magnetic field measurements on ISEE 1 and 2 and IMP 8 at widely separated positions in the earth's foreshock. This technique separates temporal and spatial variations within the foreshock. It is found that the solar wind acceleration associated with backstreaming ions is correlated with the amplitude of the MHD turbulence, and that the largest decelerations are seen close to the bow shock. The density of the backstreaming ion beam is strongly correlated with distance from the shock, and decreases by about a factor of three in a distance of about 3R(e).

Bonifazi, C.↗
NASA NTRS1983

The plasmaspheric electric field as measured by ISEE 1

The electrodynamics of the plasmasphere has been a topic of considerable interest. Models predict a space charge buildup, or Alfven layer, at the inner edge of the ring current which opposes the dawn-dusk convection electric field in the magnetosphere and thus shields the plasmasphere from the convection electric field. The current study has the objective to present data from the ISEE 1 double cylindrical probe instrument. All measurements reported were made in the plasmasphere with electron densities of the order of 30-50 or greater per cu cm. The average electric field pattern for quiet conditions is found to be qualitatively consistent with previous average results from whistler measurements and radar backscattering measurements. The magnitudes and gross patterns are in qualitative agreement with representative ionospheric dynamo models. The basic convective flow vectors from the penetration of the magnetospheric electric field tend to follow contours which are parallel to those of the average plasmapause boundary on the nightside.

Maynard, N. C.↗
NASA NTRS1982

Stimulation of plasma waves by electron guns on the ISEE-1 satellite

The results of the ISEE-1 satellite experiment relating to observations of the waves stimulated during electron injections, when the spacecraft is passing through the magnetosphere, the magnetosheath, and the solar wind, are discussed. It is shown that the injection of an electron beam current of the order of 10 to 60 microamperes with energies ranging from 0 to 40 eV produces enhancements in the electric wave spectrum. An attempt has been made to identify the low-frequency electrostatic wave observed below the ion plasma frequency as an ion acoustic mode, although the excitation mechanism is not clear. A coupling mechanism between the electron plasma mode and streaming electrons with energies higher than the thermal speed of the cold electron population has been proposed to explain the observations above the electron plasma frequency.

Lebreton, J.-P.↗
NASA NTRS1983

The mass dependence of wave particle interactions as observed with the ISEE-1 energetic ion mass spectrometer

Simultaneous measurements of the O(+) and H(+) distributions from two transverse acceleration events in the high altitude auroral ionosphere are presented. The data were acquired from the energetic ion mass spectrometer on the ISEE-1 satellite, in the dusk sector, on auroral field lines (L = 8-9), at geocentric radial distances of about 3 earth radii. Temporal and/or spatial fluctuations during the measurement cycle resulted in some scatter of the data points, but the transverse velocity distributions are reasonably well represented by maxwellians at energies in the few hundred eV range. The transverse temperatures were about 60 eV in both cases and no significant differences were observed between the temperatures of the O(+) and H(+). The flux intensities of the two ion species were also generally comparable.

Sharp, R. D.↗
NASA NTRS1983

Low-energy (less than 100 eV) ion pitch angle distributions in the magnetosphere by ISEE 1

Attention is given to isotropic distribution, bidirectional field alignment distribution, unidirectional field alignment distribution, and low flux, in a statistical examination of low energy ion data from the ISEE 1 plasma composition experiment whose aim was the study of pitch angle distributions in all local times of the magnetosphere. The isotropic distribution consisting of less than 10 eV ions is a persistent inner region feature, while the bidirectional field-aligned distribution consisting of warm ions is a persistent feature of the outer dayside and is seen just outside the isotropic distribution region of the nightside. On the outer nightside, the unidirectional field-aligned distribution consisting of warm ions is the dominant signature. The 'sources' of ions in various regions are discussed in view of the present and other results.

Johnson, J. F. E.↗
NASA NTRS1983

ISEE-3 - A late entry in the great comet chase

The ISEE-3 spacecraft, currently in a figure-8 traverse of the geomagnetic tail between 80-220 earth radii, is being redirected to a flyby of the Giacobini-Zinner comet in 1985. The satellite carries experiments for the solar wind plasma, magnetic field data, plasma wave and composition, radio waves, and energetic protons, and can gather data on the solar wind-comet interaction. A double lunar swingby will be employed to establish the intercept trajectory, yielding a total velocity change of 100 m/sec, with a reserve of 100 m/sec for midcourse corrections. The comet will be encountered at a distance of 3000 km in September 1985, followed by passage through the Halley's comet tail 5000 km from the nucleus in March 1986.

Farquhar, R.↗
NASA NTRS1983

Plasma wave experiment for the ISEE-3 mission

Sensitive, high resolution plasma probes for analysis of the distribution functions and plasma wave instruments for measurements of electromagnetic and electrostatic wave modes are commonly flown together to provide information on plasma instabilities and wave particle interactions. Analysis of the data for the ISEE 3 mission is provided.

Scarf, F. L.↗
NASA NTRS1984

ISEE-3 Microwave Filter Requirements

The 64 m subnet is committed to support the International Sun Earth Explorer (ISEE-3) spacecraft. The uplink and one of the downlink frequencies will be respectively, 2090 and 2217 MHz. As these two frequencies fall outside the normal DSN transmit and receive bands, the 64-m antennas present new filter requirements, which are analyzed.

Galvez, J. L.↗
NASA NTRS1984

Magnetic structure of the distant geotail from -60 to -220 earth radii - ISEE-3

ISEE-3 magnetic-field measurements in the region of the geomagnetic tail from -80 to -220 earth radii are reported and discussed. A well-ordered field structure is found, comprising two 7-8-nT lobes separated by a plasma sheet, an embedded neutral sheet with significant By fields, and an intermittent plasma-sheet boundary layer with 5-nT-amplitude (peak-to-peak) electromagnetic waves. The plasma-sheet Bz distribution changes from principally northern orientation near the earth to an approximately equal north-south distribution at 200-220 earth radii. These findings are considered to be in general agreement with magnetic-reconnection models of the magnetosphere, with reconnection either throughout the region observed (in tearing-mode or plasmoid-formation models) or at a constant (about 220-earth-radii) or variable (40-80 to 220-earth-radii) X line (in X-line models).

Tsurutani, B. T.↗
NASA NTRS1984

A survey of dayside flux transfer events observed by ISEE 1 and 2 magnetometers

Flux transfer events (FTEs), observed on both the interior and exterior of the dayside magnetopause region by the ISEE 1 and 2 spacecraft, are noted to be a feature of the magnetopause region covered by the spacecraft when the magnetic field in the magnetosheath has a southward component, but not when it is northward. During periods of southward magnetosheath field, the average number and recurrence time of FTE signatures/magnetopause crossing are similar to those observed in the magnetopause interior, implying that the magnetosheath and magnetosphere FTEs are aspects of the same physical phenomenon. It is speculated that FTEs may provide the dominant means of flux transfer required for the driving of geomagnetic disturbances.

Rijnbeek, R. P.↗