SEARCH · Engineering Papers

Results for “Charged-particles”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4

All sources NASA NTRS DOE OSTI

NASA NTRS1974

Isotopic composition of low energy beryllium in the galactic cosmic rays

The multielement charged-particle telescope on the IMP-5 satellite obtained data essentially continuously for more than three years in the interplanetary medium under stable instrument conditions which have made it possible to separate the H, He, and Be isotopes in the galactic cosmic radiation using the technique of double dE/dx vs residual E and particle range measurements. Special emphasis is placed on demonstrating that in the energy range from 50 to 150 MeV/nucleon the instrument clearly resolved Be-7 vs Be-9. A detailed analysis of approximately 100 Be events collected over the mission lifetime yields the ratios (Be-7/Be) = 0.50 plus or minus 0.07, (Be-9/Be) = 0.41 plus or minus 0.10, and (Be-10/Be) = 0.09 plus or minus 0.10. These results are consistent with current models of galactic cosmic ray propagation after taking account of the effects of solar modulation.

Garcia-Munoz, M.↗

NASA NTRS1974

Sodium D-line emission from Io - Sputtering and resonant scattering hypothesis

A model is presented in explanation of the observation of sodium D-line emission from Io. The model involves: (1) charged-particle sputtering of sodium from Io's surface, (2) ejection of sodium into a cloud surrounding Io, and (3) resonant scattering of incident sunlight. Observational consequences and tests of the proposed model are also discussed.

Matson, D. L.↗

NASA NTRS1975

An analysis of space environment effects on performance and missions of a Solar Electric Propulsion Stage (SEPS)

The development of an analysis which addresses the problems of degrading space environmental effects on the performance and missions of a Solar Electric Propulsion Stage (SEPS) is reported. A detailed study concerning the degrading effects of the Van Allen Belt charged-particle radiation on specific spacecraft subsystems is included, along with some of the thermal problems caused by electromagnetic radiation from the sun. The analytical methods used require the integration of two distinct analyses. The first, is a low-thrust trajectory analysis which uses analytical approximations to optimum steering for orbit raising, including three-dimensional plane change cases. The second is the conversion of the Vette time-averaged differential energy spectra for protons and electrons into a 1-MeV electron equivalent environment as a function of spatial position and thickness of various shielding materials and solar-cell cover slides.

Mcglathery, D. M.↗

NASA NTRS1975

Apollo 17 mission Report. Supplement 6: Calibration results for gamma ray spectrometer sodium iodide crystal

A major difficulty in medium energy gamma-ray remote sensing spectroscopy and astronomy measurements was the high rate of unwanted background resulting from the following major sources: (1) prompt secondary gamma-rays produced by cosmic-ray interactions in satellite materials; (2) direct charged-particle counts; (3) radioactivity induced in the detector materials by cosmic-ray and trapped protons; (4) radioactivity induced in detector materials by the planetary (e.g., earth or moon) albedo neutron flux; (5) radioactivity induced in the detector materials by the interaction of secondary neutrons produced throughout the spacecraft by cosmic-ray and trapped proton interactions; (6) radioactivity induced in spacecraft materials by the mechanisms outlined in 3, 4, and 5; and (7) natural radioactivity in spacecraft and detector materials. The purpose of this experiment was to obtain information on effects 3, 4, and 5, and from this information start developing calculational methods for predicting the background induced in the crystal detector in order to correct the Apollo gamma-ray spectrometer data for this interference.

Dyer, C.↗

NASA NTRS1975

The Pioneer 10 plasma analyzer results at Jupiter

Results are reported for the Pioneer 10 plasma-analyzer experiment at Jupiter. The analyzer system consisted of dual 90-deg quadrispherical electrostatic analyzers, multiple charged-particle detectors, and attendant electronics; it was capable of determining the incident plasma-distribution parameters over the energy range from 100 to 18,000 eV for protons and from approximately 1 to 500 eV for electrons. Data are presented on the interaction between the solar wind and the Jovian magnetosphere, the interplanetary ion flux, observations of the magnetosheath plasma, and traversals of the bow shock and magnetopause. Values are estimated for the proton isotropic temperature, number density, and bulk velocity within the magnetosheath flow field as well as for the beta parameter, ion number density, and magnetic-energy density of the magnetospheric plasma. It is argued that Jupiter has a reasonably thick magnetosphere somewhat similar to earth's except for the vastly different scale sizes involved.

Wolfe, J. H.↗

NASA NTRS1976

Microchannel detector array for X-rays and UV

Device employs sensitive photoelectric electrodes and solid-state memory, can be used at visible UV and X ray wavelengths, includes nonmagnetic proximity focusing, and is immune to high energy charged-particle background.

Timothy, J. G.↗

NASA NTRS1976

The journey to Jupiter

The Pioneer missions to Jupiter are reviewed, and the observations made by the two probes are discussed. The spacecraft are described along with their launches, instrument packages, and trajectories. The major results of the micrometeorite, plasma, magnetic-field, and charged-particle experiments are summarized. The structure of Jupiter's magnetosphere is illustrated, spectroscopic and photometric observations by the Pioneers are discussed, and measurements of the Jovian atmosphere and gravitational field are examined. The measured masses and densities of the Galilean satellites are given, and future prospects for the Pioneer spacecraft are noted, including the possibility that Pioneer 10 may still be in contact with earth when it crosses the boundary between the solar system and interstellar space.

Hall, C. F.↗

NASA NTRS1975

Electron plasma oscillations associated with type III radio emissions and solar electrons

Results of an extensive search for electron plasma oscillations associated with type III radio noise bursts are presented which were obtained by analyzing 87 type III bursts detected in plasma-wave and charged-particle measurements carried out by IMP 6, 7, and 8. Only one case is found for which plasma oscillations were associated with electrons of solar origin; at least eight events are identified in which no plasma oscillations were detected even though electrons from solar flares were clearly evident. The type III emissions are compared with similar radiation coming from upstream of earth's bow shock at the harmonic of the local electron plasma frequency, and quantitative calculations of the rate of conversion from plasma oscillatory energy to electromagnetic radiation are performed. The results show that electron plasma oscillations are seldom observed in association with solar electron events and type III radio bursts at 1.0 AU and that neither the type III emissions nor the radiation from upstream of the bow shock can be adequately explained by a current model for the coupling of electron plasma oscillations to electromagnetic radiation. Several possible explanations are considered for this discrepancy between theory and observations.

Gurnett, D. A.↗

NASA NTRS1976

Observations of Mercury's magnetic field

Magnetic-field observations made during the third encounter of Mariner 10 with Mercury are discussed along with implications of an intrinsic field for the planetary interior. The data obtained confirm the presence of characteristic bow-shock, magnetosheath, and magnetosphere regions surrounding the planet and also indicate that Mercury occupies a much larger portion of its magnetosphere than does earth. Combined plasma, charged-particle, and magnetic-field data establish that the origin of the field is intrinsic to the planet rather than associated with an induction process due to solar-wind flow. Spherical harmonic analysis of the field data shows that the internal field of the planet is well described by a centered dipole with a moment of 5.0 by 10 to the 22nd power gauss-cu cm and oriented within 12 deg of the normal to the orbital plane in the same sense as earth. Surface intensities are deduced to be between about 300 and 800 gammas. It is concluded that an active dynamo is a more likely candidate than fossil magnetization for the origin of the field.

Ness, N. F.↗

NASA NTRS1976

Interactions of the plasma sheet with the lunar surface at the Apollo 14 site

Calculations of the magnetic shadow zones of lunar-based particle detectors are extended to include the effects of local remanent magnetic fields. At the Apollo 14 site, the local magnetic field is approximated as that of a dipole. Numerically calculated open and shadowed zones are shown to be in agreement with quiet-time plasma-sheet observations of the charged-particle lunar-environment experiment. An analysis of three storm-time observations indicates that magnetic shadowing can significantly alter the near-lunar-surface electrostatic potential distribution.

Reiff, P. H.↗

NASA NTRS1976

Angular distribution of particle fluxes in rotating systems

Charged-particle pitch-angle distributions at one point on a magnetic drift surface in a rapidly rotating axisymmetric mirroring system (such as Jupiter's magnetosphere would be in the absence of the 10-deg dipole tilt) are related to those at another point by Liouville's theorem. If the distribution function in the rotating frame is gyrotropic; i.e., if it is independent of the phase angle of the gyration, it is gyrotropic at all points on that drift surface. Examples are given of 'pancake', 'dumbbell', and isotropic distributions when they are observed from the nonrotating frame at different points on a drift surface.

Northrop, T. G.↗

NASA NTRS1976

Chemistry and spectroscopy of the Jovian atmosphere

A comprehensive review is given of the chemistry and spectroscopic studies of the Jovian atmosphere. Thermochemical equilibrium models for determining atmospheric composition are considered along with possible disequilibrating processes, and studies of the photochemistry of H2, CH4, NH3, H2S, and PH3 using the modeling methods are summarized. It is shown that photodissociation and advection are the major disequilibrating processes in Jupiter's atmosphere, that lightning and charged-particle bombardment are relatively minor factors in the planet's bulk chemistry, and that the existence of living organisms on the planet is highly improbable. Spectroscopic investigations of Jupiter are discussed, emphasizing recent observations of absorption bands due to CH4, NH3, H2, He, and D. Spectroscopic abundance determinations are examined for H2, HD, CH4, CH3D, NH3, C2H6, C2H2, and PH3. Upper limits are given for the abundances of several unobserved gases in the visible atmosphere, including H2S, HCl, SiH4, benzene, purines, pyrimidines, and their derivatives.

Prinn, R. G.↗

NASA NTRS1976

Equilibrium and disequilibrium chemistry of adiabatic, solar-composition planetary atmospheres

The impact of atmospheric and cloud-structure models on the nonequilibrium chemical behavior of the atmospheres of the Jovian planets is discussed. Quantitative constraints on photochemical, lightning, and charged-particle production of organic matter and chromophores are emphasized whenever available. These considerations imply that inorganic chromophore production is far more important than that of organic chromophores, and that lightning is probably a negligibly significant process relative to photochemistry on Jupiter. Production of complex molecules by gas-phase disequilibrium processes on Saturn, Uranus, and Neptune is severely limited by condensation of even simple intermediates.

Lewis, J. S.↗

NASA NTRS1977

Solar particle propagation from 1 to 5 AU

The radial variation of the interplanetary propagation of solar cosmic rays is investigated on a grand scale by performing a statistical analysis of charged-particle data obtained by Pioneers 10 and 11 from launch to Jovian encounter (i.e., at distances of 1 to 5 AU). A numerical propagation model is adopted which includes diffusion, convection, and adiabatic deceleration, as well as a variable power-law diffusion coefficient. The study of solar particle events is carried out by analyzing individually each of five key parameters that are uniquely defined in each solar particle event: the time to maximum flux starting from the initial release at the sun, the anisotropy at the time to maximum flux, the flux at that time, the time width of the event at half the flux at the time to maximum, and the decay time. Combined results for the proton energy ranges from 3.4 to 5.2 MeV and 24 to 30 MeV are presented, the average radial diffusion coefficients between 1 and 5 AU are determined for each energy range, and it is found that the combination of a near-impusive injection with a temporally constant spectral index produces a reasonably good fit to the high-energy data but not as good a fit to the low-energy data. Implications of the results obtained are discussed for cosmic-ray propagation theory, solar modulation studies, and interplanetary acceleration of solar particles.

Zwickl, R. D.↗

NASA NTRS1977

Cosmic ray investigation for the Voyager missions: Energetic particle studies in the outer heliosphere - and beyond

The Voyager mission cosmic ray detector system, consisting entirely of solid-state charged-particle detectors, is designed to measure the energy spectrum of electrons in the range 3 to 110 MeV and the energy spectra and elemental composition of cosmic ray nuclei from hydrogen through iron in the range 1 to 500 MeV/nuc; for isotopes of hydrogen through sulfur the range is approximately 2 to 75 MeV/nuc. The cosmic ray investigation deals with the energy content, origin and acceleration process, and dynamics of cosmic rays in the galaxy, with particular attention given to low-energy phenomena in interstellar space and the outer solar system. The precise measurement of three-dimensional stream patterns of nuclei from H to Fe, as well as electrons over a wide energy range, is the data acquisition program emphasized.

Stone, E. C.↗

NASA NTRS1978

Power density in direct nuclear-pumped He-3 lasers

The interaction of neutron beams with He-3 gas is of interest for nuclear pumped lasers. The effects of spectral dependence of the neutron beam, neutron attenuation in the gas-filled laser tube, and transport of the charged-particle He-3(n, p)He-3 reaction products are treated in detail. An expression for the energy density as a function of position within the tube, tube radius, operating pressure, and neutron fluence is given. The maximum energy density within the optical cavity is achieved when the tube radius is 3.26/P where P (atm) is the operating pressure. The variation of radius by 50% above and below optimum will change the energy density at most by 10%, although performance degrades quickly for radii outside this range. If the optimum tube radius is used for each operating pressure, then the power density on the centerline (kW/cu cm) is given as 9.3 x 10 to the -18th power times the operating pressure times flux in a thermal neutron environment of flux (n/sq cm sec).

Wilson, J. W.↗

NASA NTRS1978

Quadrispherical LEPEDEAS for ISEE's-1 and -2 plasma measurements

A new generation of spaceflight instrumentation for comprehensive measurements of plasmas within the earth's magnetosphere and its environs is described. These quadrispherical low energy proton and electron differential energy analyzers (LEPEDEAS) for the ISEE's-1 and -2 spacecraft are capable of determining the directional intensities of positive ions and electrons over all but 2 percent of the 4 pi sr solid angle for charged-particle velocity vectors at the spacecraft positions. The energy range of this instrumentation is E/Q of 1 eV to 45 keV with good energy and angular resolutions. An example of inflight observations within the earth's magnetosheath is presented.

Frank, L. A.↗

NASA NTRS1978

Preferential enhancements of the solar flare-accelerated nuclei carbon to zinc from about 20-300 MeV/nucleon

IMP 8 satellite measurements with a charged-particle telescope are examined which show that three large solar flares in late 1977 displayed preferential enhancements of abundances from C through Fe at energies of about 20 to 400 MeV/nucleon. It is found that the differential energy spectra of C, O, Mg, Si, and Fe, as well as protons and helium, are best fitted by power laws in energy per nucleon or rigidity with an index of 2.3 + or - 0.2, that the spectra of most of the even-Z nuclei have essentially the same slope, and that all the enhancements were independent of energy in the range from 20 to 300 MeV/nucleon. A plot of enhancement factor vs. Z is presented which clearly demonstrates the preferential enhancement of abundances with increasing Z in one of the solar flares, where the nuclei reached such high energies that they must have escaped the corona fully stripped of electrons. Implications for theories of solar-flare acceleration of the nuclei are considered.

Dietrich, W. F.↗