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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1971

Magnetospheric plasma - Sources, wave-particle interactions and acceleration mechanisms.

Some of the basic problems associated with magnetospheric physics are reviewed. The sources of magnetospheric plasma, with auroral particles included as a subset, are discussed. The possible ways in which the solar wind plasma can gain access to the magnetosphere are outlined. Some important consequences of wave-particle interactions are examined. Finally, the basic mechanisms which energize or accelerate particles by reconnection and convection are explained.

Speiser, T. W.↗
NASA NTRS1972

Pressure and current effects on the thermal efficiency of an MPD arc used as a plasma source

Measurements of arc voltage and energy loss to the cooled electrodes of a magnetoplasmadynamic (MPD) arc, operating without an applied magnetic field, were made at chamber pressures of 26 to 950 torr, argon mass flow rates of 0.08 to 44 g/s and current of 200 to 2000 A. The resulting arc thermal efficiency varied from 22% at a chamber pressure of 26 torr to 88% at 950 torr. Thermal efficiency was only weakly dependent on arc current. It is concluded that the MPD arc operating without an applied magnetic field and at higher pressure than normally used in thruster applications is a reliable and efficient steady-state plasma source.

Pivirotto, T. J.↗
NASA NTRS1980

Detection of energetic hydrogen molecules in Jupiter's magnetosphere by Voyager 2 - Evidence for an ionospheric plasma source

The discovery of energetic (approximately 1 MeV/nuc) H3 and H2 molecules in Jupiter's magnetosphere is reported. The data, obtained with the LECP instrument on Voyager 2, showed these molecules to be present throughout the magnetosphere and as far as 180 Jupiter radii from the planet, in the 'magnetospheric wind' region. Although the relative abundances of H3 and H2 do not show a monotonic trend with distance from Jupiter, the intervals of highest abundance were found in the outer magnetosphere. As an example, in the radial range 51-56 Jupiter radii, of the dayside magnetosphere, the abundances of H3 and H2 (0.60-0.95 MeV/nuc) were about 20 and 13-25% that of He, respectively, and the He abundance was about 1-2% that of H. Since H3(+) is expected to be an important constituent of Jupiter's ionosphere, the data provide strong evidence that, in addition to Io, the ionosphere may be an important local plasma source for the Jovian energetic particles. The measurements reported may represent the first detection in nature of molecules at energies as high as 1 MeV/nucleon.

Hamilton, D. C.↗
NASA NTRS1971

Experimental investigations of a uranium plasma pertinent to a self-sustaining plasma source

The research is pertinent to the realization of a self-sustained fissioning plasma for applications such as nuclear propulsion, closed cycle MHD power generation using a plasma core reactor, and heat engines such as the nuclear piston engine, as well as the direct conversion of fission energy into optical radiation (nuclear pumped lasers). Diagnostic measurement methods and experimental devices simulating plasma core reactor conditions are discussed. Studies on the following topics are considered: (1) ballistic piston compressor (U-235); (2) high pressure uranium plasma (natural uranium); (3) sliding spark discharge (natural uranium); (4) fission fragment interaction (He-3 and U-235); and (5) nuclear pumped lasers (He-3 and U-235).

Schneider, R. T.↗
NASA NTRS1973

A pulsed xenon megawatt arc plasma source

The exhaust of the source flowing into vacuum was measured by Thomson scattering diagnosis. Mean electron temperatures and densities were found to be 4-8 eV and of order ten to the 13th power cm/3 respectively over the 8 cm exhaust diameter at 30 cm from the source. Large shot to shot variations were noted. After a transient spike passes, these conditions persist during the power time of 125 microsecond. These exhaust conditions are marginal for evaluation of a proposed near resonant charge exchange pumped laser theory.

Michels, C. J.↗
NASA NTRS1973

A pulsed xenon megawatt arc plasma source

The exhaust of the source flowing into vacuum was measured by Thomson scattering diagnosis. Mean electron temperatures and densities were found to be 4-8 eV and on the order of 10 trillion per cu cm respectively, over the 8 cm exhaust diameter at 30 cm from the source. Large shot to shot variations were noted. After a transient spike passes, these conditions persist during the power time of 125 microsec. These exhaust conditions are marginal for evaluation of a proposed near resonant charge exchange pumped laser theory.

Michels, C. J.↗
NASA NTRS1977

Jupiter's internal magnetic field geometry relevant to particle trapping

Some field-geometric features of relevance to particle trapping in the inner magnetosphere and polar-cap regions of Jupiter are described using an internal-field model that includes terms up to the order of n equals 3 (octupole). Adiabatic particle parameters for detectors on Pioneers 10 and 11 during their flights through Jupiter's inner magnetosphere are determined along with the configuration of the intersections of particle drift shells with the planetary ionosphere. Possible correlations between drift-shell contours and the planet-locked characteristics of Jovian decametric radio emission are investigated, and longitudinal asymmetries of the ionospheric plasma source function are analyzed. It is shown that if the ionosphere is the main source of magnetospheric plasma, the latitude dependence of the plasma source function should have a considerable effect on the longitudinal asymmetry of the corotating plasma.

Roederer, J. G.↗
NASA NTRS1978

A self-consistent model of a corotating Jovian magnetosphere

In the rotation-dominated model of the Jovian magnetosphere, proposed in the present paper, the plasma current distribution is dynamically consistent with the magnetic field. The model is constructed under the assumptions of an ionospheric plasma source without pitch angle scattering; loss-free radiation transport through flux tube interchange diffusion; and a static balance between centrifugal force and magnetic stress. Using these assumptions, a dynamic equation is derived for a self-consistent field configuration having a single adjustable parameter that is related to the plasma source strength. The equation is solved by an iterative technique. The self-consistent field resembles a radially distorted dipole field, rather than the flat magnetodisk configuration inferred from Pioneer data. The implication is that such a magnetodisk field would require an equatorial plasma source rather than a source at the feet of the field lines.

Carbary, J. F.↗
NASA NTRS1978

A dense plasma ultraviolet source

The intense ultraviolet emission from the NASA Hypocycloidal-Pinch (HCP) plasma is investigated. The HCP consists of three disk electrodes whose cross section has a configuration similar to the cross section of a Mather-type plasma focus. Plasma foci were produced in deuterium, helium, xenon, and krypton gases in order to compare their emission characteristics. Time-integrated spectra in the wavelength range from 200 nm to 350 nm and temporal variations of the uv emission were obtained with a uv spectrometer and a photomultiplier system. Modifications to enhance uv emission in the iodine-laser pump band (250 to 290 nm) and preliminary results produced by these modifications are presented. Finally, the advantages of the HCP as a uv over use of conventional xenon lamps with respect to power output limit, spectral range, and lifetime are discussed.

Lee, J. H.↗
NASA NTRS1980

Survey of the plasma electron environment of Jupiter: A view from Voyager

The plasma environment within Jupiter's bow shock is considered in terms of the in situ, calibrated electron plasma measurements made between 10 eV and 5.95 keV by the Voyager plasma science experiment (PLS). Measurements were analyzed and corrected for spacecraft potential variations; the data were reduced to nearly model independent macroscopic parameters of the local electron density and temperature. It is tentatively concluded that the radial temperature profile within the plasma sheet is caused by the intermixing of two different electron populations that probably have different temporal histories and spatial paths to their local observation. The cool plasma source of the plasma sheet and spikes is probably the Io plasma torus and arrives in the plasma sheet as a result of flux tube interchange motions or other generalized transport which can be accomplished without diverting the plasma from the centrifugal equator. The hot suprathermal populations in the plasma sheet have most recently come from the sparse, hot mid-latitude "bath" of electrons which were directly observed juxtaposed to the plasma sheet.

Scudder, J. D.↗