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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 73 records · Page 4
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NASA NTRS1975

A relationship between synchronous altitude electron fluxes and the auroral electrojet

Simultaneous observations during four substorms are reported from the Lockheed auroral particle spectrometer on ATS 5 and the University of Alberta meridian magnetometer chain. During the four events studied there was a good correlation between the magnitude of the trapped electron fluxes in the energy range from 1.8 to 53 keV and the magnitude of the electrojet current as measured by a station in the magnetometer chain at a latitude close to that expected for the ATS conjugate point. A model electrojet is constructed based on the work of Coroniti and Kennel (1972) which gives a good absolute agreement between the two measured quantities. The results are consistent with the convection electric field's remaining approximately constant during a substantial portion of each of the substorms studied. The temporal variations of the electrojet were apparently controlled by conductivity changes in the ionosphere as determined by the precipitating auroral electrons.

Sharp, R. D.↗
NASA NTRS1975

A relationship between synchronous-altitude electron fluxes and the auroral electrojet, appendix A

Simultaneous observations during four substorms are reported from the Lockheed auroral particle spectrometer on ATS-5 and the University of Alberta meridian magnetometer chain (Canada). During the four events studied, there was a good correlation between the magnitude of the trapped electron fluxes in the energy range from 1.8 to 53 keV and the magnitude of the electrojet current as measured by a station in the magnetometer chain at a latitude close to that expected for the ATS conjugate point. The Hall effect was studied and a model electrojet was constructed which gave a good absolute agreement between the two measured quantities. The results are consistent with the convection electric field remaining approximately constant during a substantial portion of each of the substorms studied. The temporal variations of the electrojet were apparently controlled by conductivity changes in the ionosphere as determined by the precipitating auroral electrons.

Sharp, R. D.↗
NASA NTRS1976

Coordinated ATS 5 electron flux and simultaneous auroral observations

An attempt is made to correlate ATS 5 plasma data with all-sky photographic data taken at Thompson and Gillam, Manitoba. The fields of view of the Canadian stations cover the projected field line position of the satellite. Trapped electron fluxes at the satellite and the simultaneously measured auroral activity near the projected foot of the satellite field line were compared for several days of varying substorm activity with all-sky camera data, which was in the form of time-varying luminosity plots. The observed auroral intensification coincident with plasma injection shows that on a broad scale the auroras are correlated well with the magnetospheric trapped plasma; however, there is a lack of detailed correlation between the fine structure of the trapped plasma fluxes and the small scale auroral features.

Mende, S. B.↗
NASA NTRS1977

A comparison between N2/+/ 4278-A emission and electron flux in the auroral zone

Visual airglow and low-energy electron experiment data from the Atmosphere Explorer D satellite are used to measure variations in N2(+) density and mixing in the nighttime auroral zone. The intensity of the 4278-A N2(+) emission, proportional to energy flux deposited in N2 by energetic electrons, is determined by a method which corrects for ground reflection affecting the satellite data. Calculations related to electron energy flux are found to show a slight variance from the theoretical predictions of Rees and Luckey (1974). Evidence for high-energy proton precipitation on the southern edge of the aurora and for the presence of parallel electric fields in the altitude range 150 to 800 km is also discussed.

Kasting, J. F.↗
NASA NTRS1975

Rocket measurement of auroral electron fluxes associated with field-aligned currents

A rocket-borne experiment using an electron and proton energy spectrometer is described, with particular reference to calibration and data reduction procedures. An upper limit of the measured proton flux is found to be 1,000,000 protons per sq cm sec sr keV. The characteristics of particle precipitation observed during flight over the auroral band are evaluated. The electron flux in regions of maximum flux tends to be the most field-aligned in the energy interval with the highest intensity.

Pazich, P. M.↗
NASA NTRS1987

Field-aligned electron flux oscillations that produce flickering aurora

Measurements of energetic electrons that produce flickering aurora were made by a pair of sounding rockets, launched during a slowly evolving auroral breakup. Both payloads passed through a broad inverted-V structure. A component of the electron distribution function was closely aligned with the magnetic field over a broad energy range that extended from low energies up to the inverted-V differential energy flux peak. Measurements of the field-aligned component showed the presence of order of magnitude coherent flux oscillations. Source altitudes between 4000 and 8000 km were derived from velocity dispersion of the flux oscillations.

Mcfadden, J. P.↗
NASA NTRS1974

Polar cap auroral electron fluxes observed with Isis 1

Three types of auroral particle precipitation have been observed over the polar caps, well inside the auroral oval, by means of the soft particle spectrometer on the Isis 1 satellite. The first type is a uniform, very soft (about 100 eV) electron 'polar rain' over the entire polar cap; this may well be present with very weak intensity at all times, but it is markedly enhanced during worldwide geomagnetic storms. A second type of precipitation is a structured flux of electrons with energies near 1 keV, suggestive of localized 'polar showers'; it seems likely that these are the cause of the sun-aligned auroral arcs that have been observed during moderately quiet conditions. During periods of intense magnetic disturbance this precipitation can become very intense and exhibit a characteristic pattern that we have come to call a 'polar squall'.

Winningham, J. D.↗
NASA NTRS1975

The latitudinal morphology of 10-eV to 10-keV electron fluxes during magnetically quiet and disturbed times in the 2100-0300 MLT sector

Electron and proton data from Isis 1 and 2 have been used to examine the change in the latitudinal morphology of auroral particle fluxes as a function of substorm time in the dipole magnetic local time period from 2100 to 0300. Clear and repeatable systematics in the latitudinal morphology were observed during the various phases of a substorm, allowing the substorm phase to be identified on the basis of particle data alone. Based on this study, a new phenomenological substorm model is presented which relates particle precipitation from various parts of the magnetotail to auroral oval morphology.

Winningham, J. D.↗
NASA NTRS1988

Observations of intense trapped electron fluxes at synchronous altitudes

The concept of flux limiting in the outer radiation belt proposed by Kennel and Petschek (1966) has been tested in a dynamic situation by using data acquired with instruments aboard the SCATHA satellite. A case-by-case analysis of 12 events for evidence of flux limiting under various magnetospheric conditions is made. The reuslts indicate qualitative agreement with the flux limiting theory for all the events studied. Even the quiescent events and hard-spectrum events are consistent with flux limiting. The limiting flux level at any instant appears to depend strongly on the recent history of the trapped electrons and plasma in the outer magnetosphere.

Davidson, G. T.↗
NASA NTRS1995

Theoretical position-velocity diagrams of flux, electron density, and electron temperature in Herbig-Haro objects

Many features of Herbig-Haro objects can be reproduced using a kinematical bow shock model. We use the model to generate position-velocity (PV) diagrams of flux in H-alpha (O I) lambda lambda 6300+63, (S II) lambda lambda 6716+31, (O III) lambda lambda 4959+5007, and (C I) lambda lambda 9823+50, line ratios of (O I)/H-alpha, (O I)/(S II), (S II)/H-alpha, H-alpha(S II), and (O III)/H-alpha, electron density N(sub e), and electron temperature T(sub e). We show how position-velocity diagrams of N(sub e) and flux vary with shock velocity. By matching the diagrams from single lines, the line ratios, and N(sub e) with observations, we determined a narrow range of shock parameters for HH 1F, 2(A' + H), and 43 (B + C). We model the N(sub e) features of HH 2(A' + H) as a superposition of two bowshocks. We also show that the effects of slight misalignments of the two diagrams to be divided can produce artifacts in the line ratios and N(sub e) which obliterate the physical features. We show that N(sub e) in HH 1 can only be explained using the kinematical model by taking these misalignments into account.

Indebetouw, Remy↗
NASA NTRS1989

Plasma and energetic electron flux variations in the Mercury 1 C event - Evidence for a magnetospheric boundary layer

Charge-particle and magnetic-field data obtained during the first encounter (on March 29, 1974) of Mariner 10 with the planet Mercury are reexamined, and a new interpretation of the Mariner 10 energetic electron, plasma electron, and magnetic field data near the outbound magnetopause at Mercury is presented. It is shown that Mariner 10 sampled the hot substorm energized magnetospheric plasma sheet for the first 36 sec of the C event and, for the next 48 sec, alternatively sampled hot (plasma sheet) and cold (boundary-layer magnetosheathlike) plasma regions. It is argued that the counting rate of the ID1 event (i.e., a particle event triggering detector D1 but not the D2, D3, or D7 detectors) throughout the C event most probably represents a pulse pileup response to about 35-175 keV electrons, rather than the nominal above-175 keV electrons presumed in the earlier interpretations.

Christon, S. P.↗