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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

HEAO-B and -C engineering design and scientific objectives

The HEAO-B observatory will be launched in late 1978 for a one-year mission to analyze individual X-ray objects and extended sources in detail using a high precision X-ray telescope. The energy range of the telescope is 0.1 keV to 4 keV. Four interchangeable instruments are at the focal plane; a high resolution imaging instrument, an imaging proportional counter, a focal plane crystal spectrometer, and a solid state spectrometer. A monitor proportional counter will collect data independently of the telescope. The HEAO-C observatory is a scanning mission and will be launched in 1979 for six months operation. It will contain two cosmic ray experiments and a gamma ray spectrometer.

Dailey, C. C.↗
NASA NTRS1979

Investigations in cosmic and gammaray astronomy and nuclear instruments

Work has continued throughout the reporting period on reduction of data from the Fall 1976 flight of the MSFC-UAH Cosmic Ray Experiment. During this period a major effort was undertaken to improve and rebuild the experiment. This was accomplished and a successful flight was completed in September 1978 from Pierre, South Dakota with the new instrument.

Source record↗
NASA NTRS1979

An instrument to measure the spectrum of cosmic ray iron and other nuclei to above 100 GeV/nucleon

A balloon-borne instrument system for the study of cosmic ray composition in the energy region beyond 100 GeV/nucleon is described. The large area detector incorporates an ionization spectrometer or calorimeter to determine the energy of the incident particles which is calibrated in flight by a gas Cerenkov counter filled with freon 12 at 20 psi. Calibration of calorimeter response indicates that the effects of ionization energy loss and nucleon fragmentation are correctly accounted for in a Monte Carlo simulation. A charge measuring module consisting of five scintillators and a lucite Cerenkov counter is used to determine the charge and position of the incoming particles. A spatial resolution of 5 to 10 cm has been obtained by using the ratios of pulse heights in different photomultiplier tubes aimed at the same scintillators within the module. The detector represents the heaviest cosmic ray experiment that can be flown over 30 km using the dynamic launching technique commonly employed.

Arens, J. F.↗
NASA NTRS1978

Recent progress in the development of transition radiation detectors

Transition-radiation detectors have been used in several recent cosmic-ray experiments for particle identification at energies E/mc-squared of at least about 1000. In order to optimize the design of such detectors and to use them for energy measurements over a broad energy range, it is necessary to study the details of the transition-radiation process. Experimental results are presented which test the theoretical predictions more precisely and at higher energies than in previous experiments. The dependence of the interference pattern in the frequency spectrum on the radiator dimensions is studied, and the total transition-radiation yield generated by electrons in various radiators is measured over a very wide energy range, from 5 to 300 GeV. The significance of the individual experimental parameters in the design of transition radiation detectors is reviewed, and the characteristics of transition-radiation detectors capable of measuring particle energies over the range E/mc-squared from about 300 to 100,000 are discussed.

Cherry, M. L.↗
NASA NTRS1980

Observations of energetic ions and electrons in Saturn's magnetosphere

Observations of the magnetosphere of Saturn made by the cosmic-ray experiment on board Pioneer 11 are summarized. Detailed energy spectra and angular distributions of protons from 0.2 to 22 MeV and electrons from 0.1 to 2 MeV were obtained, together with measurements of helium nuclei between 0.65 and 22 MeV/n. The time histories of proton and electron data suggest a division of the Saturn magnetosphere into three regions: (1) an outer magnetosphere between 17 and 7.5 Saturn radii, which is characterized by monotonically increasing fluxes and spectral hardening inward from the magnetosphere, with large changes in low-energy electron angular distributions; (2) a slot region between 7.5 and 4 Saturn radii where marked decreases in proton and low-energy electron fluxes are observed, apparently due to the presence of Dione, Tethys and Enceladus; and (3) an inner region between 4 Saturn radii and the ring edge, which exhibits sharp increases in proton fluxes with energies up to 20 MeV, which are broken near the orbits of Mimas, Janus and possibly S 11. A sharp cutoff of proton and electron fluxes is observed just beyond the nominal edge of the A ring.

Trainor, J. H.↗
NASA NTRS1981

Saturn's ring current and inner magnetosphere

The Voyager 1 magnetic field observations at Saturn are shown in a graph. The departure of the oberved magnetic field from the field of a dipole is considered. The observed field magnitude is appreciable less than that of the model dipole at small radial distances and greater than the model dipole in the more distant magnetosphere. These characteristics can be understood by introducing a model current system similar to a system originally applied to observations of the Jovian magnetic disk. Saturn's ring current has important implications for charged-particle motion in Saturn's magnetosphere, particularly the absorption of trapped radiation by its many satellites and rings. The absorption signature observed by the Voyager 1 cosmic ray experiment near the orbital position of Rhea illustrates well the effects of Saturn's ring current on charged particle trajectories.

Connerney, J. E. P.↗
NASA NTRS1982

The isotopes of H through C in galactic cosmic rays

The charge, energy spectra, and isotopic composition of hydrogen through nitrogen have been studied with the GSFC/UNH cosmic ray experiments on board the Pioneer 10 and 11 spacecraft. Good charge and mass resolution have been obtained by utilizing three parameter analysis (i.e., two measurements of delta E and a measurement of the residual kinetic energy of stopping particles). This method allows isotopic resolution for the High Energy Telescope (HET) which operates over a typical energy range of 30-56-MeV/nuc for He. The observations will be over solar quiet times from September 1976-September 1977. The resolution, methods of analysis, spectra, and isotopic composition will be presented and discussed where the statistical significance of H to C isotopes is meaningful.

Smith, B.↗
NASA NTRS1983

Temporal variations of the anomalous oxygen component

Data from the cosmic ray experiment on Voyagers 1 and 2 was used to examine anomalous oxygen in the time period from launch in 1977 to the end of 1981. Several time periods were found where large periodic (typically 26 day) temporal variations of the oxygen intensity between approximately 5 - 15 MeV/nuc are present. Variations in intensity by up to a factor of 10 are observed during these periods. Several characteristics of these variations indicate that they are not higher energy extensions of the low energy particle (approximately 1 MeV/nuc) increases found in many corotating interaction regions (CIR's). Many of these periodic temporal variations are correlated with similar, but much smaller, recurrent variations in the 75 MeV proton rate. Voyager 1 and Voyager 2 counting rates were compared to estimate the local radial gradient for both the protons and the oxygen. The proton gradients during periods of both maximum and minumum fluxes are consistent with the overall positive radial gradients reported by others from Pioneer and near-Earth observations, supporting the view that these variations are due to local modulation of a source outside the radial range of project measurements. In contrast, the oxygen gradients during periods of maximum proton flux differ in sign from those during minimum proton fluxes, suggesting that the origin of the oxygen variations is different from that of the protons.

Cummings, A. C.↗
NASA NTRS1985

Changes in the energy spectrum of anomalous oxygen and helium during 1977 - 1985

Data from the cosmic-ray experiment on the Voyager spacecraft was used to assure the energy spectrum of anomalous O and He during the period 1977 to 1985. These spectra change dramatically after the middle of 1980, with the peak or plateau region of the differential spectrum shifting to a higher energy. This change appears to be related to the reversal of the solar magnetic field and could imply that particle drifts are important to the acceleration or propagation of these particles.

Cummings, A. C.↗
NASA NTRS1985

Injection of energetic particles following the gamma-ray flares on June 7, 1980, as observed on Helios 1

On June 7, 1980, two flares with impulsive gamma-ray emission were observed at 0117 Ut and 0312 UT. Measurements of the University of Kiel cosmic-ray experiment on HELIOS-1 are presented. The first approx. 0.5 MeV electrons escaped from the Sun to interplanetary space simultaneously with the hard X-ray burst. For the 0312 UT flare the protons and alpha-particle in the 3 - 20 MeV/nucleon range were injected from the Sun with a delay of approx. 40 min, followed by two subsequent new emissions.

Neustock, H. H.↗
NASA NTRS1985

Coronal propagation of flare associated electrons and protons

A statistical study of characteristic times and intensities of 36 solar particle events observed between 1977 and 1979 by the Kiel Cosmic Ray Experiment on board HELIOS-1 and -2 has been carried out. For approx. 0.5 MeV electrons we order the times of maximum and the absolute intensities with respect to angular distance from the parent flare. Discussion of coronal parameters in terms of Reid's model leads to typical time constants for coronal diffusion and escape.

Schellert, G.↗
NASA NTRS1985

Changes in the energy spectrum of anomalous oxygen and helium during 1977-1985

Data was used from the cosmic ray experiment on the Voyager spacecraft to measure the energy spectrum of anomalous O and He during the period 1977 to 1985. These spectra are found to change dramatically after the middle of 1980, with the peak of plateau region of the differential spectrum shifting to a higher energy. This change appears to be related to the reversal of the solar magnetic field and could imply that particle drifts are important to the acceleration of propagation of these particles.

Cummings, A. C.↗
NASA NTRS1985

Measurement of interaction cross section of cosmic ray Fe nuclei (E4 GeV/N) with Al target

Although the study of relatvistic heavy ion interaction encumbered by the low intensities of the incident heavy nuclei in cosmic ray experiments, however, one can use a suitable structure of detector to attain a result with a reasonable accuracy. A cross section value of Fe(E 4 GeV/N) with Al is presented. CR-39 was used as detector and Al as target. The cross section value is estimated using maximum likelihood method.

Ren, G. X.↗
NASA NTRS1983

The delayed energetic particle event of June 6-10, 1979

Energetic particle observations carried out with the ISEE-3 Medium-Energy Cosmic Ray experiment during the flare event of June 6-10, 1979 are reported. An expanded time history of the He nuclei particle spectra is given, and particle trajectory angles are identified with respect to the earth-sun line. The backward flow of the particle stream following the shock was analyzed, and it is found that the shock continued to accelerate particles beyond 1 AU from the sun. Polar plots of the number of protons counted in each sector of observation are given with their corresponding magnetic field directions.

Von Rosenvinge, T. T.↗
NASA NTRS1985

Helios 1 energetic particle observations of the solar gamma-ray/neutron flare events of 1982 June 3 and 1980 June 21

The characteristics of the energetic particles associated with the solar gamma-ray/neutron flare events of June 3, 1982 and June 21, 1980 observed by the Goddard cosmic-ray experiment on Helios 1 (at heliocentric distances of 0.57 and 0.54 AU, respectively) differ in several important respects from typical sonar particle increases. In particular, the June 3, 1982 event has a proton energy spectrum which fits a remarkable flat power law in kinetic energy with a spectral index of 1.2, an electron/proton ratio of 1 at 4 MeV, and a small but well-defined precursor event that began some 3 hr before the impulsive flare increase. Similar energetic particle precursors were observed for the gamma-ray associated 1980 June 21 and June 7 flare events. At energies less than about 40 MeV, the particle onset time measured for the June 3, 1982 event is anomalous, suggesting that these lower energy particles may have been released at the sun about 1-2 minutes before the higher energy particles.

Mcdonald, F. B.↗
NASA NTRS1992

Effects of the LDEF environment on the Ag/FEP thermal blankets

This presentation was made by Francois Levadou at the NASA Langley Research Center LDEF materials workshop, November 19-22, 1991. It represents the results to date on the examination of silvered teflon thermal blankets primarily from the Ultra-heavy Cosmic Ray Experiment and also from the blanket from the Park Seed Company experiment. ESA/ESTEC and Boeing conducted a number of independent measurements on the blankets and in particular on the exposed fluorinated ethylene-propylene (FEP) layer of the blankets. Mass loss, thickness, and thickness profile measurements have been used by ESA, Boeing, and NASA LeRC to determine recession and average erosion yield under atomic oxygen exposure. Tensile strength and percent elongation to failure data, surface characterization by ESCA, and SEM images are presented. The Jet Propulsion Laboratory analysis of vacuum radiation effects is also presented. The results obtained by the laboratories mentioned and additional results from the Aerospace Corporation on samples provided by Boeing are quite similar and give confidence in the validity of the data.

Levadou, Francois↗
NASA NTRS1993

Energetic (greater than 0.2 MeV) electron bursts observed by ISEE 3 in the deep (less than 240 R(E)) geomagnetic tail

The study reports the detection by the Goddard Space Flight Center medium energy cosmic ray experiment of bursts of 0.2-2.0-MeV electrons with durations of less than 1 hr during the ISEE 3 geotail mission in October 1982 to November 1983. Bursts are observed in all tail regions, with the majority (about 60 percent) associated with encounters with the plasma sheet, about 20 percent occurring in the tail lobes and a similar number in the magnetosheath. The electron burst intensity and occurrence rate fall abruptly by around an order of magnitude at about 80-90 R(E) downtail. The majority (about 64 percent) of plasma sheet electron bursts are associated with northward B(z). Plasma sheet electron bursts associated with southward B(z) are rare (6 percent of all plasma sheet events). It is suggested that temporal variations in the electron intensity associated with substorms may be present, in addition to spatial variations reflecting the average quiet-time tail configuration.

Richardson, I. G.↗
NASA NTRS1994

Experimental impacts into Teflon targets and LDEF thermal blankets

The Long Duration Exposure Facility (LDEF) exposed approximately 20 sq m of identical thermal protective blankets, predominantly on the Ultra-Heavy Cosmic Ray Experiment (UHCRE). Approximately 700 penetration holes greater than 300 micron in diameter were individually documented, while thousands of smaller penetrations and craters occurred in these blankets. As a result of their 5.7 year exposure and because they pointed into a variety of different directions relative to the orbital motion of the nonspinning LDEF platform, these blankets can reveal important dynamic aspects of the hypervelocity particle environment in near-earth orbit. The blankets were composed of an outer teflon layer (approximately 125 micron thick), followed by a vapor-deposited rear mirror of silver (less than 1000 A thick) that was backed with an organic binder and a thermal protective paint (approximately 50 to 75 micron thick), resulting in a cumulative thickness (T) of approximately 175 to 200 microns for the entire blanket. Many penetrations resulted in highly variable delaminations of the teflon/metal or metal/organic binder interfaces that manifest themselves as 'dark' halos or rings, because of subsequent oxidation of the exposed silver mirror. The variety of these dark albedo features is bewildering, ranging from totally absent, to broad halos, to sharp single or multiple rings. Over the past year experiments were conducted over a wide range of velocities (i.e., 1 to 7 km/s) to address velocity dependent aspects of cratering and penetrations of teflon targets. In addition, experiments were performed with real LDEF thermal blankets to duplicate the LDEF delaminations and to investigate a possible relationship of initial impact conditions on the wide variety of dark halo and ring features.

Hoerz, F.↗