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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
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

The storm and poststorm evolution of energetic /35-560 keV/ radiation belt electron distributions

Detailed Explorer 45 equatorial observations of the storm and poststorm structure of radiation-belt electrons (35 to 560 keV) for L values between 1.7 and 5.2 are presented. Injection during major storms results in electron pitch-angle distributions and radial profiles that are greatly distorted from their quiet-time equilibrium structure. Following storms, the pitch-angle distributions return to their prestorm shape over a period of several days. This shape is maintained as electron fluxes decay back to the quiet-time levels. The equatorial radial profiles slowly return to their prestorm equilibrium structure over a period of a few weeks and then maintain that structure.

Lyons, L. R.↗
NASA NTRS1993

Electron distributions in the inner Jovian magnetosphere: Voyager 1 observations

Using several improvements in the analysis of the observations of the Low Energy Charged Particle (LECP) experiment on Voyager 1, electron phase space densities in the inner Jovian magnetosphere (5 - 10 R(sub J) were first calculated at constant first and second invariants (represented by mu and K, respectively), based on the LECP measurements. The calculated electron phase space density profiles show that in the inner Jovian magnetosphere there exist evident time and longitude variations, energetic electron injections, and present radial transport and distributed losses. To study the radial and pitch angle diffusions of Jovian electrons, we have calculated the phase space densities in the K-L space. It is found that the electron population in the inner Jovian magnetosphere seems to consist of two components: electrons radially diffusing from a main external source and electrons generated from local sources. The radially diffusing electrons have a relatively time stationary and isotropic distribution, while the locally created electrons mainly concentrate around the equatorial plane and have relatively lower energies, in comparison with the inward diffusing electrons. Consequently, the sources of precipitation losses to the ionosphere must be primarily electrons transported from outer sources, and the major precipitations occur in the inner magnetosphere (L less than 7.5 R(sub J). In the inner Jovian magnetosphere (L = 5 to approximately 10 R(sub J)) it is estimated that for electrons with magnetic moment mu = 300 MeV/G, the diffusion coefficient D is roughly 10(exp -8) to approximately 10(exp -6) R(exp 2)(sub J)/s, and the lifetime against the diffusion losses is of the order of 10(exp 4) to approximately 10(exp 6) s.

Ye, G.↗
NASA NTRS1990

Electron distributions in the plasma sheet boundary layer - Time-of-flight effects

The electron edge of the plasma sheet boundary layer lies lobeward of the ion edge. Measurements obtained near the electron edge of the boundary layer reveal low-speed cutoffs for earthward and tailward-flowing electrons. These cutoffs progress to lower speeds with deeper penetration into the boundary layer, and are consistently lower for the earthward-directed electrons than for the tailward-direction electrons. The cutoffs and their variation with distance from the edge of the boundary layer can be consistently interpreted in terms of a time-of-flight effect on recently reconnected magnetic field lines. The observed cutoff speeds are used to estimate the downtail location of the reconnection site.

Onsager, T. G.↗
NASA NTRS1977

The Jovian relativistic electron distribution in interplanetary space from 1 to 11 AU - Evidence for a continuously emitting 'point' source

From observations of Jovian electrons with instrumentation on the Pioneer 10 spacecraft, it is concluded from both their spatial distribution and their modulation in interplanetary space by solar corotating interaction regions (CIRs) that, whatever the scale size of the Jovian magnetotail, the escape of relativistic electrons occurs within 1 AU of the planet. Thus, on the large scale of the heliosphere, Jupiter appears as a continuously emitting 'point source'. The close approach of the spacecraft at 9.6 AU to a possible extension of a magnetotail early in 1976 is discussed. From recurring intensity increases of approximately 1-MeV protons, it is concluded that CIRs have not dissipated even at about 11 AU.

Pyle, K. R.↗
NASA NTRS1989

Anisotropic thermal electron distributions in the solar wind

This paper presents data on ISEE 3 observations of unusually anisotropic core electrons detected in the solar wind near 1 AU, which exhibited temperature (T) ratios T-parallel/T-perpendicular of 1.5 to 4. Distinct anisotropy events are described, together with the observed correlations between core temperature anisotropy and various other solar wind parameters. It was found that the periods of extreme electron anisotropy tended to be coincident with intervals of double ion beam, suggesting similar causal mechanisms for the two phenomena.

Phillips, J. L.↗
NASA NTRS2023

Simulating Electron Distribution Function in the Pulsating Aurora Using Particle and Wave Data of ARASE Satellite

Decades lasting research on the pulsating aurora suggested that this phenomenon forms as result of interactions between the magnetospheric keVs electrons and whistler-mode chorus waves. Arase satellite observation reported the direct evidence for this process confirming in situ measurement of highly correlated precipitated electrons and chorus wave activity. This paper presents the theoretical analysis of this observational event based on the SuperThermal Electron Transport (STET) code that simulates the highly dynamic environment of measured waves and particle data. Specifically, the STET code simulated results confirms the delicate loss-cone observation results of this mission and further reveals the broader energy range of precipitated electron fluxes that was not measurable by Arase satellite.

George V Khazanov↗
NASA NTRS1982

Anomalous auroral electron distributions due to an artificial ion beam in the ionosphere

Results are reported for the perturbation of the auroral ionosphere by the operation of an ion gun which injected about 100 mA of 25-eV Ar(+) ions at upgoing pitch angles over a discrete auroral arc. The major effects observed were the excitation of intense broadband electric field fluctuations at zero-10 kHz, and the appearance of streaming and isotropic heating in different parts of superthermal electron velocity space. A scenario is explored in which electron runaway or streaming is expected between the trapping speed and the critical velocity for cyclotron interactions with the waves, where the streaming electrons carry the current that would be carried by thermals or energetic electrons in the absence of the waves. A current of about 1.0 microA/sq m is carried by the streaming electrons. The gun-associated electrons were anomalous in the sense that their anisotropy was the opposite of that observed in the natural aurora.

Moore, T. E.↗
NASA NTRS1976

Study of the extra-ionic electron distributions in semi-metallic structures by nuclear quadrupole resonance techniques

A straightforward self-consistent method was developed to estimate solid state electrostatic potentials, fields and field gradients in ionic solids. The method is a direct practical application of basic electrostatics to solid state and also helps in the understanding of the principles of crystal structure. The necessary mathematical equations, derived from first principles, were presented and the systematic computational procedure developed to arrive at the solid state electrostatic field gradients values was given.

Murty, A. N.↗
NASA NTRS1987

The electron distribution function upstream from the earth's bow shock

A general analytic theory for the distribution function of particles backstreaming from an arbitrary shock in a magnetized plasma is presented. Particle motions are shown to be restricted to two-dimensional planes. A general form for the source term describing upstreaming particles accelerated at the shock is presented along with explicit source terms for planar and parabolic shocks. The origin and form of the escape velocity cutoff for a shock in a magnetized plasma are discussed. The distribution function upstream of a finite planar shock and a parabolic shock in two dimensions is calculated, and an analytic approximation of the cutoff velocity at points in the upstream region is derived. The theory is then applied to the earth's bow shock, calculating distribution functions and the nature and spatial variation of the cutoff velocity. The theory for the particle distribution upstream of the bow shock is compared with the model of Filbert and Kellogg (1979).

Cairns, Iver H.↗
NASA NTRS1999

Insensitivity of Line-Ratio Diagnostics to Steady-State Non-Maxwellian Electron Distributions in Solar Corona

We examine the idea that the corona is heated by a population of nonthermal particles. An upper limit on the size of the nonthermal population is derived by assuming that all of the radiation and conduction losses in the corona are provided by the nonthermal tail of the particle distribution. Only a very small percentage of nonthermal particles are allowed. These particles have a negligable effect on temperature sensitive line ratios typically observed in the EUV (Extreme Ultraviolet Radiation).

Falconer, D. A.↗