Search NASA⌕ Search

SEARCH · Search NASA

Results for “hydrogen component”

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.

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

At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

Effect of component compression on the initial performance of an IPV nickel-hydrogen cell

An experimental method was developed for evaluating the effect of component compression on the charge and discharge voltage characteristics of a 3 1/2 in. diameter boiler plate cell. A standard boiler plate pressure vessel was modified by the addition of a mechanical feedthrough on the bottom of the vessel which permitted different compressions to be applied to the components without disturbing the integrity of the stack. Compression loadings from 0.94 to 27.4 psi were applied by suspending weights from the feedthrough rod. Cell voltages were measured for 0.96-C, 55-min charge and for 1.37-C, 35-min and 2-C, 24-min discharges. An initial change in voltage performance on both charge and discharge as the loading increased was attributed to seating of the components. Subsequent variation of the compression from 2.97 to 27.4 psi caused only minor changes in either the charge or the discharge voltages. Several one month open-circuit voltage stands and 1100 cycles under LEO conditions at the maximum loading have produced no change in performance.

Gahn, Randall F.↗
NASA NTRS1974

The effect of suprathermal protons on the physical conditions in Seyfert galaxy nuclei

The physical conditions in a high density hydrogen gas heated and ionized by suprathermal protons were investigated, with application to the gas in the nuclear region of Seyfert galaxies. The gas is assumed optically thick to Lyman and Balmer line radiation. Mechanisms by which the radiation from the gas can balance the heating by the fast protons were investigated, and minimum values for the mass of gas were estimated. Under certain conditions, the suprathermal atoms themselves can cool the ambient gas by rescattering the line radiation into the optically thin region in the wings of the line. This mechanism, called optical reverberation, can enhance the broad component of the hydrogen lines produced by inelastic atomic collisions and yield line widths consistent with those observed in Seyfert and quasar spectra. Also discussed is the possibility of achieving dynamic equilibrium of the ambient gas by balancing the momentum transfer from the suprathermals with gravitational attraction of a massive central source.

Ptak, R.↗
NASA NTRS1975

The effect of suprathermal protons on the physical conditions in Seyfert galaxy nuclei

Physical conditions in a high-density hydrogen gas heated and ionized by suprathermal protons are investigated, and the results are applied to the gas in the nuclear region of Seyfert galaxies. The gas is assumed to be optically thick to Lyman and Balmer line radiation. Mechanisms by which the radiation from the gas can balance the heating by the fast protons are investigated, and minimum values for the mass of gas are estimated. Under certain conditions, the suprathermal atoms themselves can cool the ambient gas by rescattering the line radiation into the optically thin region in the wings of the line. This mechanism, optical reverberation, can enhance the broad component of the hydrogen lines produced by inelastic atomic collisions and yield line widths consistent with those observed in Seyfert and quasar spectra. If this mechanism is important, the Lyman decrement can depend strongly on the temperature and density of the ambient hydrogen. The possibility is discussed of achieving dynamic equilibrium of the ambient gas by balancing the momentum transfer from the suprathermals with gravitational attraction of a massive central source.

Ptak, R.↗
NASA NTRS1994

Constraints on molecular gas in cooling flows and powerful radio galaxies

We searched for molecular gas in a heterogeneous sample of five radio-loud galaxies (three of which are inferred to be in cooling flow clusters) using the Swedish-European Southern Observatory (Swedish-ESO) Submillimeter Telescope. We do not detect CO in emission in any of the cluster sources at a 3 sigma level of typically 15 mK. White et al. (1991) have suggested column densities of N(sub H) approximately 10(exp 21)/sq cm in these clusters with a spatial covering factor of order unity and a total mass of M approximately 10(exp 12) solar mass. Our limits are inconsistent with these column densities and spatial covering factor unless the molecular gas is very cold (kinetic temperature close to 2.7 K) or there only a few clouds along each line of sight. We estimate minimum temperatures in the range approximately 20-30 K. We find that clouds of atomic and molecular hydrogen require strict fine-tuning of parameter space in order to satisfy the requirements for the large column densities N(sub H) approximately 10(exp 21)/sq cm, unit covering factor, and a small number of clouds along the line of sight. Currently the only way molecular gas can be responsible for the X-ray absorption and still be consistent with our observations is if (1) there is of order one cloud along the line of sight and (2) the optical depth in C-12 1 to 0 is less than 10. In addition, we present a Very Large Array (VLA) image of NGC 4696 which suggests this object is a member of the class of 'amorphous cooling flow radio sources.' The C-12 1 to 0 line is detected in emission in PKS 0634-206, a classical double radio galaxy which is rich in extended optical emission line gas. The estimated molecular gas mass is M(sub mol) approximately 3 x 10(exp 9) solar mass and is much larger than that of the ionized component detected in hydrogen alpha suggesting that the emission-line nebula is radiation bounded.

O'Dea, Christopher P.↗
NASA NTRS1981

The effect of the charge exchange source on the velocity and 'temperature' distributions and their anisotropies in the earth's exosphere

The velocity distribution of atomic hydrogen in the earth's exosphere is calculated as a function of altitude and direction taking into account both the classic exobase source and the higher-altitude plasmaspheric charge exchange source. Calculations are performed on the basis of a Monte Carlo technique in which random ballistic trajectories of individual atoms are traced through a three-dimensional grid of audit zones, at which relative concentrations and momentum or energy fluxes are obtained. In the case of the classical exobase source alone, the slope of the velocity distribution is constant only for the upward radial velocity component and increases dramatically with altitude for the incoming radial and transverse velocity components, resulting in a temperature decrease. The charge exchange source, which produces the satellite hydrogen component and the hot ballistic and escape components of the exosphere, is found to enhance the wings of the velocity distributions, however this effect is not sufficient to overcome the temperature decreases at altitudes above one earth radius. The resulting global model of the hydrogen exosphere may be used as a realistic basis for radiative transfer calculations.

Hodges, R. R., Jr.↗
NASA NTRS1976

SAS-2 galactic gamma ray results, 1

Continuing analysis of the data from the SAS-2 high energy gamma-ray experiment has produced an improved picture of the sky at photon energies above 35 MeV. On a large scale, the diffuse emission from the galactic plane is the dominant feature observed by SAS-2. This galactic plane emission is most intense between galactic longitude 310 and 45 deg, corresponding to a region within 7kpc of the galactic center. Within the high-intensity region, SAS-2 observes peaks around galactic longitudes 315 deg, 330 deg, 345 deg, 0 deg, and 35 deg. These peaks appear to be correlated with such galactic features and components as molecular hydrogen, atomic hydrogen, magnetic fields, cosmic ray concentrations, and photon fields.

Thompson, D. J.↗
NASA NTRS1985

Sulfate-reducing bacteria: Microbiology and physiology

The sulfate reducing bacteria, the first nonphotosynthetic anaerobic bacteria demonstrated to contain c type cytochromes, perform electron transfer coupled to phosphorylation. A new bioenergetic scheme for the formation of a proton gradient for growth of Desulfovibrio on organic substrates and sulfate involving vectors electron transfer and consistent with the cellular localization of enzymes and electron transfer components was proposed. Hydrogen is produced in the cytoplasm from organic substrates and, as a permease molecule diffuses rapidly across the cytoplasmic membrane, it is oxidized to protons and electrons by the periplasmic hydrogenase. The electrons only are transferred across the cytoplasmic membrane to the cytoplasm where they are used to reduce sulfate to sulfide. The protons are used for transport or to drive a reversible ATPOSE. The net effect is the transfer of protons across the cytoplasmic membrane with the intervention of a proton pump. This type of H2 cycling is relevant to the bioenergetics of other types of anaerobic microorganisms.

Peck, H. D.↗
NASA NTRS1985

Two new color-selected magnetic DA white dwarfs

The discovery of two magnetic white dwarfs culled from blue star surveys is reported. The surveys were carried out with the Mount Lemnon 1.5-meter reflecting telescope attached to a two-holer polarimeter/photometer. Spectral observations of the objects, (PG 1533 - 057, and K813 - 14), indicate the presence of hydrogen and Zeeman components. On the basis of dipolar field simulations, it is shown that PG 1533 - 057 has a polar field strength of 31 megagauss (MG) while K813 - 14 has a polar field strength of 29 MG. A third known white dwarf has a polar field strength of 18 MG. All the dwarfs had temperatures in the 11,000-20,000 K range. The possibility that a significant fraction of isolated magnetic degenerate stars could be the progeny of magnetic accreting binary systems is considered.

Liebert, J.↗
NASA NTRS1986

Cosmic X-ray physics

The analysis of the beryllium-filtered data from Flight 17.020 was completed. The data base provided by the Wisconsin diffuse X-ray sky survey is being analyzed by correlating the B and C band emission with individual velocity components of neutral hydrogen. Work on a solid state detector to be used in high resolution spectroscopy of diffuse or extend X-ray sources is continuing. A series of 21 cm observations was completed. A paper on the effects of process parameter variation on the reflectivity of sputter-deposited tungsten-carvon multilayers was published.

Mccammon, D.↗
NASA NTRS1994

Advanced nickel-hydrogen spacecraft battery development

Eagle-Picher currently has several advanced nickel-hydrogen (NiH2) cell component and battery designs under development including common pressure vessel (CPV), single pressure vessel (SPV), and dependent pressure vessel (DPV) designs. A CPV NiH2 battery, utilizing low-cost 64 mm (2.5 in.) cell diameter technology, has been designed and built for multiple smallsat programs, including the TUBSAT B spacecraft which is currently scheduled (24 Nov. 93) for launch aboard a Russian Proton rocket. An advanced 90 mm (3.5 in.) NiH2 cell design is currently being manufactured for the Space Station Freedom program. Prototype 254 mm (10 in.) diameter SPV batteries are currently under construction and initial boilerplate testing has shown excellent results. NiH2 cycle life testing is being continued at Eagle-Picher and IPV cells have currently completed more than 89,000 accelerated LEO cycles at 15% DOD, 49,000 real-time LEO cycles at 30 percent DOD, 37,800 cycles under a real-time LEO profile, 30 eclipse seasons in accelerated GEO, and 6 eclipse seasons in real-time GEO testing at 75 percent DOD maximum. Nickel-metal hydride battery development is continuing for both aerospace and electric vehicle applications. Eagle-Picher has also developed an extensive range of battery evaluation, test, and analysis (BETA) measurement and control equipment and software, based on Hewlett-Packard computerized data acquisition/control hardware.

Coates, Dwaine K.↗
NASA NTRS1994

A bipolar outflow of ionized gas in K3-50A: H76 alpha radio recombination line and continuum observations of K3-50

The H II regions near K3-50 (G70.3 + 1.6) have been imaged at high angular resolution (approximately 1 sec .3) in the continuum and the recombination lines H76(sub alpha and He76(sub alpha) using the Very Large Array (VLA). The helium line is detected in only the brightest component K3-50A while the hydrogen line is detected in three components (K3-50A, B and C1). K3-50A shows a pronounced velocity gradient of approximately 150 km/sec/pc along its major axis (P.A. = 160 deg); in addition a wide range of line widths are observed, from 20 to 65 km/sec. Kinematics from the line data and the morphology of the continuum emission suggest that the ionized material associated with K3-50A is undergoing a high-velocity bipolar outflow.

Depree, C. G.↗
NASA NTRS1996

Infrared emission spectra of candidate interstellar aromatic molecules

Interstellar dust is responsible, through surface reactions, for the creation of molecular hydrogen, the main component of the interstellar clouds in which new stars form. Intermediate between small, gas-phase molecules and dust are the polycyclic aromatic hydrocarbons (PAHs). Such molecules could account for 2-30% of the carbon in the Galaxy, and may provide nucleation sites for the formation of carbonaceous dust. Although PAHs have been proposed as the sources of the unidentified infrared emission bands that are observed in the spectra of a variety of interstellar sources, the emission characteristics of such molecules are still poorly understood. Here we report laboratory emission spectra of several representative PAHs, obtained in conditions approximating those of the interstellar medium, and measured over the entire spectral region spanned by the unidentified infrared bands. We find that neutral PAHs of small and moderate size can at best make only a minor contribution to these emission bands. Cations of these molecules, as well as much larger PAHs and their cations, remain viable candidates for the sources of these bands.

Non-NASA Center↗
NASA NTRS2019

Electrochemical Solutions for Advanced Life Support

The Oxygen Generating Assembly (OGA) on-board the International Space Station (ISS) employs a polymer electrolyte membrane (PEM) water electrolysis cell stack to electrochemically dissociate water into its two components – oxygen and hydrogen. Oxygen is provided to the cabin atmosphere for crew respiration while the hydrogen is delivered to a carbon dioxide reduction system to recover oxygen as water. The design of the OGA evolved over a number of years to arrive at the system solution that is currently operational on ISS. Future manned missions to space will require advanced technologies that eliminate the need for resupply from earth and feature in-situ resource utilization to sustain crew life and to provide useful materials to the crew. The architects planning such missions should consider all potential solutions at their disposal to arrive at an optimal vehicle solution that minimizes crew maintenance time, launch weight, installed volume and energy consumption demands. Skyre is developing new technologies through funding from NASA, the Department of Energy, and internal investment based on PEM technology that could become an integral part of these new vehicle solutions. At varying stages of Technology Readiness Level (TRL) are: an oxygen concentrator and compressor that can separate oxygen from an air stream and provide an enriched oxygen resource for crew medical use and space suit recharge without any moving parts in the pure oxygen stream; a regenerative carbon dioxide removal system featuring a PEM-based sorbent regenerator; a carbon dioxide reduction system that electrochemically produces organic compounds that could serve as fuels or as a useful intermediary to more beneficial compounds; and an electrochemical hydrogen separator and compressor for hydrogen recycle. The technical maturity of these projects is presented along with pertinent performance test data that could be beneficial in future study efforts.

Roy, Robert J.↗
NASA NTRS1975

Winter bulge and diurnal variations in hydrogen inferred from AE-C composition measurements

In situ mass spectrometric measurements of ion and neutral particle thermospheric compositions have been used to infer the latitudinal and diurnal variations of thermospheric atomic hydrogen for solstice conditions. Local time-dependent and local time-independent components of the observed hydrogen distribution were separated on the basis of a model generated by expanding the log of neutral hydrogen concentration in terms of spherical harmonics. Results are compared with analogous data on N2 concentration; the comparison reveals an anticorrelation between gas temperature and hydrogen concentration. The slope of this anticorrelation line represents the 'zero flux condition' from the exosphere theory of Hodges (1973), thus further bearing out the conclusion that exospheric flow is the dominant process governing the global distribution of hydrogen.

Brinton, H. C.↗
NASA NTRS1981

Two-component Fermi-liquid theory - Equilibrium properties of liquid metallic hydrogen

It is reported that the transition of condensed hydrogen from an insulating molecular crystal phase to a metallic liquid phase, at zero temperature and high pressure, appears possible. Liquid metallic hydrogen (LMH), comprising interpenetrating proton and electron fluids, would constitute a two-component Fermi liquid with both a very high component-mass ratio and long-range, species-dependent bare interactions. The low-temperature equilibrium properties of LMH are examined by means of a generalization to the case of two components of the phenomenological Landau Fermi-liquid theory, and the low-temperature specific heat, compressibility, thermal expansion coefficient and spin susceptibility are given. It is found that the specific heat and the thermal expansion coefficient are vastly greater in the liquid than in the corresponding solid, due to the presence of proton quasiparticle excitations in the liquid.

Oliva, J.↗
NASA NTRS2005

Feasibility Assessment for Pressure Casting of Ceramic-Aluminum Composites for NASA's Propulsion Applications

Feasibility assessment of pressure casting of ceramic-aluminum composites for NASA% propulsion applications is summarized. A combination of several demonstration projects to produce three unique components for liquid hydrogen-oxygen rocket engine% flanges, valves and turbo-pump housing are conducted. These components are made from boron carbide, silicon carbide and alumina powders fabricated into complex net shaped parts using dry green powder compaction, slip casting or a novel 3D ink-jet printing process, followed by sintering to produce performs that can be pressure cast by infiltration with molten aluminum. I n addition, joining techniques are also explored to insure that these components can be assembled into a structure without degrading their highly tailored properties. The feasibility assessment was made to determine if these new materials could provide a significant weight savings, thereby reducing vehicle launch costs, while being durable materials to increase safety and performance for propulsion system.

Lee, Jonathan A.↗
NASA NTRS1986

Assessment of commercially available and experimental hydrogen electrodes

NASA Lewis Research Center is currently involved in advanced cell component development for nickel-hydrogen cells and batteries. Long life, high energy density, improved performance and reliability are required for energy storage systems in future space missions. Commercially available as well as experimental hydrogen electrodes were assessed and copared to the state-of-the-art hydrogen electrode that is currently being used in nickel-hydrogen batteries. These electrodes were evaluated by scanning electron microscopy and standard electrochemical polarization measurements. Production variables such as Teflon content and platinum catalyst loading were considered in order to assess various hydrogen electrods with regard to the different electrode manufacturing processes.

Charleston, J. A.↗
NASA NTRS1986

Assessment of commercially available and experimental hydrogen electrodes

NASA Lewis Research Center is currently involved in advanced cell component development for nickel-hydrogen cells and batteries. Long life, high energy density, improved performance and reliability are required for energy storage systems in future space missions. Commercially available as well as experimental hydrogen electrodes were assessed and compared to the state-of-the-art hydrogen electrode that is currently being used in nickel-hydrogen batteries. These electrodes were evaluated by scanning electron microscopy and standard electrochemical polarization measurements. Production variables such as Teflon content and platinum catalyst loading were considered in order to assess various hydrogen electrodes with regard to the different electrode manufacturing processes.

Charleston, Jo Ann↗