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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 901 records · Page 50
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

The isotopes of H and He in solar cosmic rays

The isotopic composition of H and He in solar cosmic rays was studied with the solar galactic cosmic ray experiment on the Orbiting Geophysical Observatory, OGO-6. Averaging over 20 days of data from seven flare events during 1969, the ratios He-3/-He-4 = 0.10 + or - 0.02, D/H (76) .0003 and T/H (76) .0001 in the 4 to 5 MeV/nucleon energy range were obtained. In addition, large variations were found in the relative abundance of He-3 from event of event, with a maximum ratio of He-3/He-4 = 0.26 + or - 0.08 observed on October 14 and 15, 1969. The relative abundance of He-3 and D during this event does not seem to be consistent with existing calculations of the nuclear interaction orgin of these isotopes.

Garrard, T. L.↗
NASA NTRS1974

A summary of the mechanical design, testing and performance of the IMP-H and J attitude control systems

The main aspects of the attitude control system used on both the IMP-H and J spacecraft are presented. The mechanical configuration is described. Information on all the specific components comprising the flight system is provided. The acceptance and qualification testing of both individual components and the installed system are summarized. Functional information regarding the operation and performance in relation to the orbiting spacecraft and its mission is included. Related topics which are discussed are: (1) safety requirements, (2) servicing procedures, (3) anomalous behavior, and (4) pyrotechnic devices.

Metzger, J. R.↗
NASA NTRS1973

Competition between charge exchange and chemical reaction - The D2/+/ + H system

Study of the special features of molecular charge exchange and its competition with chemical reaction in the case of the D2(+) + H system. The trajectory surface hopping (TSH) model proposed by Tully and Preston (1971) is used to study this competition for a number of reactions involving the above system. The diatomics-in-molecules zero-overlap approximation is used to calculate the three adiabatic surfaces - one triplet and two singlet - which are needed to describe this system. One of the significant results of this study is that the chemical reaction and charge exchange are strongly coupled. It is also found that the number of trajectories passing into the chemical regions of the three surfaces depends very strongly on the surface crossings.-

Preston, R. K.↗
NASA NTRS1973

H theorem and kinetic equations for a reacting gas

A previously developed set of kinetic model equations for a chemically-reacting gas is modified. By examining closely the H theorem, a new set of constraints is obtained. These conditions are then used to determine the inelastic collision parameters proposed in the model. The kinetic equations so obtained are able to produce exactly the same rate equations as prescribed by the actual chemical reactions.

Fang, T.-M.↗
NASA NTRS1974

Autoionization states in He and H/-/ by the stabilization method

The stabilization method for positions and widths of resonances has been applied up to now only to model problems or to problems for which definitive calculations are not possible. The method is now applied to autoionization states in He and H(-), where accurate calculations are available. It is concluded that reasonably accurate results can be obtained by this method.

Bhatia, A. K.↗
NASA NTRS1973

Dust in H II regions

The observed far infrared flux of H II regions is interpreted as evidence for the presence of internal dust absorbing a fraction of Lyman continuum photons. The effect of this dust on the required number of ionizing photons and on the helium to hydrogen line intensity ratios are discussed and analytic formulae describing these effects are presented for simplified models.

Petrosian, V.↗
NASA NTRS1974

LX Persei, an eclipsing binary with H and K emission

The masses and MK classes were calculated for the eclipsing spectroscopic binary LX Persei. Its spectrum shows strong H and K emission and doubled lines in the photographic region. The Ca II emission velocity shifts vary in phase with the secondary's absorption lines and are presumably associated with this component. The stars are tentatively classed as G0 V and K0 IV, and the cooler component is the more massive by a ratio of 0.96. The system has a period of 8.0 days.

Weiler, E. J.↗
NASA NTRS1974

Observations of H alpha in HDE 226868

High-dispersion spectrograms in the red have been obtained for HDE 226868, the optical candidate for Cyg X-1. Emission is present at H alpha which varies systematically with the binary period and apparently originates in the vicinity of the B supergiant. During the period of observation a broad redshifted emission component was present throughout the cycle at a velocity of about + 200 km/sec with respect to the primary, while a similar blueshifted component appeared at -200 km/sec between photometric phases 0.2 and 0.6.

Brucato, R. J.↗
NASA NTRS1974

Absorption of laser radiation in a H-He plasma. II - Experimental measurement of the absorption coefficient

The absorption coefficients of 0.633-, 1.15-, and 3.39-micron laser radiation for a homogeneous H-He plasma have been measured in the temperature range from 12.2 to 21.7 (x 1000 K) and in the electron number density range 0.45 to 6.5 (x 10 to the 17th power per cu cm). Good agreement is found between the experimentally determined total absorption for each of the wavelengths and that calculated from theory. Furthermore, because the 3.39-micron absorption is dominated by inverse bremsstrahlung, while the 0.633-micron absorption is dominated by photoionization and resonance absorption, the experiment indicates a correct assessment by the theory of these individual absorption mechanisms.

Billman, K. W.↗
NASA NTRS1975

Polynomial coefficients of thermochemical data for the C-H-O-N system

Thermodynamic data are required input for the finite kinetics and equilibrium computer programs needed for modeling the combustion of hydrocarbons in the fields of energy and pollution research. Least squares determined coefficients of the curve-fitted thermodynamic data for 193 species in the C-H-O-N system are presented in card image form and are of suitable format for use by common computer programs.

Wakelyn, N. T.↗
NASA NTRS1975

Energy spectra and charge states of H, He, and heavy ions observed in the earth's magnetosheath and magnetotail

Observations of pulses of H, He, and heavy ions of energies greater than 0.12 MeV per charge in the magnetotail and in the magnetosheath are reported. It was found that the relative ion abundances were about 9:1:0.04, their differential energy spectra were about 1 divided by the fourth power of E, and their atomic electrons were almost completely stripped. These results suggest that they were low-energy 'quiet-time' cosmic rays accelerated within the magnetotail and the magnetosheath to the observed energies.

Fan, C. Y.↗
NASA NTRS1975

The broadening of calcium II H and K lines by helium

Laboratory measurements of widths and shifts of the Ca II H and K lines have been made under conditions simulating those in the atmospheres of metallic-line white dwarfs, namely, densities of 10 to the 21st power helium atoms per cu cm and temperatures of 4500 to 6000 K. There are significant differences in the shifts and damping constants of the two fine-structure components. The impact theory is evidently applicable to the Ca II/He system under these conditions, and the observed damping constants are fortuitously close to the predictions of conventional Lindholm-Foley/van der Waals theory. The widths and shifts have also been analyzed in terms of Lennard-Jones potential theory.

Hammond, G. L.↗
NASA NTRS1975

H alpha oscillations in sunspot umbrae

Results are reported for direct measurement of intensity fluctuations and photographic subtractions of simultaneous Doppler filtergrams of H-alpha oscillations in sunspot umbrae. The observational techniques are described, and data are presented on the intensity variations, power spectra, and specific characteristics of the oscillations. Periods for the velocity oscillations are obtained by power spectrum analysis. It is found that the oscillations are apparently continuous, and that each umbra has its own characteristic period ranging from 145 to 180 plus or minus 10 sec and a duration of at least 8 cycles. A Doppler shift of 10 km/sec, an oscillating element size of 3 sec or less, and visibility to a radius vector of about 0.9 are also observed.

Phillis, G. L.↗
NASA NTRS1975

Umbral oscillations and penumbral waves in H alpha

Examples are presented of umbral oscillations observed on Big Bear H-alpha filtergram movies, and the relation between umbral oscillations and running penumbral waves occurring in the same sunspot is investigated. Umbral oscillations near the center of the umbra are probably physically independent of the penumbral waves because the period of these umbral oscillations (150 sec) is shorter than the penumbral wave period (270 sec), but not a harmonic. Dark puffs emerge from the edge of the umbra and move outward across the penumbra, and have the same period as the running penumbral waves. These dark puffs are interpreted to be the extension of chromospheric umbral oscillations at the edge of the umbra. It is suggested that the dark puffs and the running penumbral waves have a common source: photospheric oscillations just inside the umbra.

Moore, R. L.↗
NASA NTRS1975

The 1640.4 A H-alpha line of He II observed from Skylab

Profiles obtained from NRL Skylab solar spectra of the 1640.4 A feature identified as the H-alpha line of He II are discussed and compared with theoretical profiles derived assuming (1) collisional excitation and (2) radiative recombination as the dominant excitation mechanism. Relative intensities of this line as a function of altitude above and below the solar white-light limb are also given for a representative quiet sun region and for a polar coronal hole.

Feldman, U.↗
NASA NTRS1975

Far Infrared Spectroscopy of H II Regions

The far infrared spectra of H II regions are investigated. A liquid helium cooled grating spectrometer designed to make observations from the NASA Lear Jet is described along with tests of the instrument. The observing procedure on the Lear Jet telescope is described and the method of data analysis is discussed. Results are presented from a search for the (O III) 88.16 micron line. An upper limit on the emission in this line is obtained and line detection is described. Results are compared to theoretical predictions, and future applications of fine structure line observations are discussed. Coarse resolution results are given along with calibration problems. The spectra obtained are compared to models for dust emission.

Ward, D. B.↗
NASA NTRS1975

IMS/Satellite Situation Center report. Predicted orbit plots for IMP-H-1976

Predicted orbit plots are shown in three projections. The time period covered by each set of projections is 12 days 6 hours, corresponding approximately to the period of IMP-H satellite. The three coordinate systems used are the Geocentric Solar Ecliptic system (GSE), the Geocentric Solar Magnetospheric system (GSM), and the Solar Magnetic system (SM). For each of the three projections, time ticks and codes are given on the satellite trajectories. The codes are interpreted in the table at the base of each plot. Time is given in the table as year/day/decimal hour. The total time covered by each plot is shown at the bottom of each table. An additional variable is given in the table for each time tick. For the GSM and SM projection this variable is the geocentric distance to the satellite in earth radii, and for the GSE projection the variable is satellite ecliptic latitude in degrees.

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