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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Atomic hydrogen storage method and apparatus

Atomic hydrogen, for use as a fuel or as an explosive, is stored in the presence of a strong magnetic field in exfoliated layered compounds such as molybdenum disulfide or an elemental layer material such as graphite. The compounds maintained at liquid helium temperatures and the atomic hydrogen is collected on the surfaces of the layered compound which are exposed during delamination (exfoliation). The strong magnetic field and the low temperature combine to prevent the atoms of hydrogen from recombining to form molecules.

Woollam, J. A.↗
NASA NTRS1986

Inherent weaknesses of cosmology

Sources of astrophysical evidence necessary to verify a cosmological model are reviewed. Cosmological history of the universe is divided into four epochs, each unique in its physical conditions related to observability at present. The current epoch, started after recombination of hydrogen in the universe, offers the most in observability. In earlier epochs, verifiable astrophysical evidence gradually disappeared. It seems that no astrophysical evidence has been left behind from the singularity epoch of the Universe. The gradual disappearance of astrophysical evidence ascertainable at present is the result of physical conditions structured within the cosmological models, hence indicating certain inherent weaknesses of cosmology as a verifiable physical theory.

Chiu, H.-Y.↗
NASA NTRS1989

New results in the theory of dust grain alignment

Two complementary approaches are used in an attempt to propose an appropriate formulation of the solution to the problem of magnetic alignment of grains in the diffuse and/or the more denser clouds, whatever the mechanism of rotational excitation can be. The interest of such a unified formulation is mainly that the same theoretical expression for polarization can be used everywhere, allowing for easier comparisons between regions where the physical conditions are highly different. The first consists in applying a Monte-Carlo method to a limited number of representative cases, for which all the torques acting on the grain are taken into account: impulsive random torques due to direct collisions with gas atoms, to evaporation of atoms from the surface, and to exo-energetic recombinations forming hydrogen molecules, followed by violent ejections from peculiar sites; magnetic torques. Three characteristic times are associated with these torques: the collisional damping time, the time necessary to change completely the actual sites configuration narrowly bound to the correlation time of the suprathermal torque; and the magnetic damping time. The second approach starts from a heuristic point of view. It consists in a generalization of results (Cugnon, 1983; see also Purcell and Spitzer, 1971; Greenberg, 1978) obtained for thermal alignment to the suprathermal case. It appears indeed that in two extreme cases, the thermal formulation may be used after redefinition of involved times and temperatures.

Cugnon, Pierre↗
NASA NTRS1990

Studies of the thermal and optical responses of H atoms in solid H2

It was the goal of this reserch project to model both the storage of energy in solid hydrogen in the form of atoms and the conversion of this stored energy into other forms of useful energy. The basic ideas of rocket propulsion originate in classical physics and they remain unchanged. To escape a strong gravitational field, the 'burn time' must be minimized but in negligible force fields, the burn time is unimportant and only the relative masses of rocket to fuel determine a specific exhaust velocity. It is in this latter case that low mass fuels such as hydrogen become very important. The burning of hydrogen in oxygen is a 'benchmark' fuel today providing a specific impulse of 400 seconds or better. More exotic fuels will be needed for many of the interesting explorations of the future but they still must have large energy releases per unit mass. It is in this context that propulsion based on hydrogen atom recombination receives attention and these studies will serve as engineering guides.

Gaines, James R.↗
NASA NTRS1995

Intense radio outburst from the supermassive star Eta Carinae

On five occasions between 1992 June 29 and 1994 May 3, we have used the Australia Telescope Compact Array (ATCA) to image Eta Carinae at a wavelength of 3 cm and a resolution of 1 arcsec. These observations have revealed remarkable activity. Since 1992 June, the total flux density has increase from 0.8 to 2.2 Jy, and the original single compact source has grown to a complex of sources spread over an area of about 16 sq arcsec. Strong hydrogen recombination-line spectral emission has appeared at the site of the strongest of these new sources. This recombination emission has the largest spectral width ever observed from a star, +/- 250 km/s, and reveals gas with turbulent velocities as great as 250 km/s approaching us at an average velocity of about 200 km/s. We believe that this radio outburst has been caused by a more than threefold increase of ultraviolet luminosity, and consequent ionization of previously neutral gas clouds.

Duncan, R. A.↗
NASA NTRS2017

The Atmospheric Response to High Nonthermal Electron Beam Fluxes in Solar Flares. I. Modeling the Brightest NUV Footpoints in the X1 Solar Flare of 2014 March 29

The 2014 March 29 X1 solar flare (SOL20140329T17:48) produced bright continuum emission in the far- and near-ultraviolet (NUV) and highly asymmetric chromospheric emission lines, providing long-sought constraints on the heating mechanisms of the lower atmosphere in solar flares. We analyze the continuum and emission line data from the Interface Region Imaging Spectrograph (IRIS) of the brightest flaring magnetic footpoints in this flare. We compare the NUV spectra of the brightest pixels to new radiative-hydrodynamic predictions calculated with the RADYN code using constraints on a nonthermal electron beam inferred from the collisional thick-target modeling of hard X-ray data from Reuven Ramaty High Energy Solar Spectroscopic Imager. We show that the atmospheric response to a high beam flux density satisfactorily achieves the observed continuum brightness in the NUV. The NUV continuum emission in this flare is consistent with hydrogen (Balmer) recombination radiation that originates from low optical depth in a dense chromospheric condensation and from the stationary beam-heated layers just below the condensation. A model producing two flaring regions (a condensation and stationary layers) in the lower atmosphere is also consistent with the asymmetric Fe II chromospheric emission line profiles observed in the impulsive phase.

Kowalski, Adam F.↗
NASA NTRS1988

H2 and H I emission line imaging of the ring nebula (NGC 6720)

Infrared emission-line images of the v = 1-0 S(1) transition of molecular hydrogen and Br-gamma recombination line of atomic hydrogen which cover the entire extent of NGC 6720, the Ring nebula. The maps presented here are the highest angular resolution images of these transitions yet produced for this object and have very low relative positional uncertainty. As a result, the spatial stratification of the ionized and shocked molecular zones within the nebula is clearly resolved. These data, and data from the Infrared Astronomical Satellite, are used to determine the H2, H I, and dust mass within the nebula. Energy sources for the dust heating, formation and destruction of the H2, and overall evolution of the nebula are also discussed.

Greenhouse, Matthew A.↗
NASA NTRS1962

Recombination and Mobility of Nuclear Radiation Induced Ionization in Liquid Hydrogen

In the present experiment, a stationary radioactive source (Kr-85) was allowed to produce ionization at a particular location in a flowing stream of liquid hydrogen. By measurement of the ionization collected at various points downstream for various velocities we were able to measure independently the recombination coefficient and the ionic mobility. In addition, we were able to obtain an approximate value of E, the fraction of the volumetric ionization rate which is available for volume recombination and production of ion currents.

Ionization↗
NASA NTRS1986

Use of low-energy hydrogen ion implants in high-efficiency crystalline-silicon solar cells

The use of low-energy hydrogen implants in the fabrication of high-efficiency crystalline silicon solar cells was investigated. Low-energy hydrogen implants result in hydrogen-caused effects in all three regions of a solar cell: emitter, space charge region, and base. In web, Czochralski (Cz), and floating zone (Fz) material, low-energy hydrogen implants reduced surface recombination velocity. In all three, the implants passivated the space charge region recombination centers. It was established that hydrogen implants can alter the diffusion properties of ion-implanted boron in silicon, but not ion-implated arsenic.

Fonash, S. J.↗
NASA NTRS1985

Use of low energy hydrogen ion implants in high efficiency crystalline silicon solar cells

This program is a study of the use of low energy hydrogen ion implantation for high efficiency crystalline silicon solar cells. The first quarterly report focuses on two tasks of this program: (1) an examination of the effects of low energy hydrogen implants on surface recombination speed; and (2) an examination of the effects of hydrogen on silicon regrowth and diffusion in silicon. The first part of the project focussed on the measurement of surface properties of hydrogen implanted silicon. Low energy hydrogen ions when bombarded on the silicon surface will create structural damage at the surface, deactivate dopants and introduce recombination centers. At the same time the electrically active centers such as dangling bonds will be passivated by these hydrogen ions. Thus hydrogen is expected to alter properties such as the surface recombination velocity, dopant profiles on the emitter, etc. In this report the surface recombination velocity of a hydrogen emplanted emitter was measured.

Fonash, S. J.↗
NASA NTRS2006

Multiphysics Thermal-Fluid Design Analysis of a Non-Nuclear Tester for Hot-Hydrogen Materials and Component Development

The objective of this effort is to perform design analyses for a non-nuclear hot-hydrogen materials tester, as a first step towards developing efficient and accurate multiphysics, thermo-fluid computational methodology to predict environments for hypothetical solid-core, nuclear thermal engine thrust chamber design and analysis. The computational methodology is based on a multidimensional, finite-volume, turbulent, chemically reacting, thermally radiating, unstructured-grid, and pressure-based formulation. The multiphysics invoked in this study include hydrogen dissociation kinetics and thermodynamics, turbulent flow, convective, and thermal radiative heat transfers. The goals of the design analyses are to maintain maximum hot-hydrogen jet impingement energy and to minimize chamber wall heating. The results of analyses on three test fixture configurations and the rationale for final selection are presented. The interrogation of physics revealed that reactions of hydrogen dissociation and recombination are highly correlated with local temperature and are necessary for accurate prediction of the hot-hydrogen jet temperature.

Wang, Ten-See↗
NASA NTRS2006

Analysis of Material Sample Heated by Impinging Hot Hydrogen Jet in a Non-Nuclear Tester

A computational conjugate heat transfer methodology was developed and anchored with data obtained from a hot-hydrogen jet heated, non-nuclear materials tester, as a first step towards developing an efficient and accurate multiphysics, thermo-fluid computational methodology to predict environments for hypothetical solid-core, nuclear thermal engine thrust chamber. The computational methodology is based on a multidimensional, finite-volume, turbulent, chemically reacting, thermally radiating, unstructured-grid, and pressure-based formulation. The multiphysics invoked in this study include hydrogen dissociation kinetics and thermodynamics, turbulent flow, convective and thermal radiative, and conjugate heat transfers. Predicted hot hydrogen jet and material surface temperatures were compared with those of measurement. Predicted solid temperatures were compared with those obtained with a standard heat transfer code. The interrogation of physics revealed that reactions of hydrogen dissociation and recombination are highly correlated with local temperature and are necessary for accurate prediction of the hot-hydrogen jet temperature.

Wang, Ten-See↗
NASA NTRS2009

Irradiation with molecular hydrogen as an accelerated total dose hardness assurance test method for bipolar linear circuits

High dose rate irradiation with hydrogen stress is proposed as an accelerated total dose test method for bipolar linear circuits. The method is validated across process and circuit technologies with five parts that are commonly used in space: a comparator (LM193 from National Semi-conductor), a voltage regulator (HSYE-117 RH from Intersil), a voltage reference (LT1019 from Linear Technology), a JFET input op amp (OP42 from Analog Devices) and a temperature transducer (AD590 from Analog Devices). The testing technique could rapidly establish an upper bound to the low dose rate response of parts in space and help with the part selection process in the design phase of a mission. The technology dependence and the viability of this technique are qualitatively explored using a physical model describing the dose rate response and the effect of hydrogen in bipolar technologies. The model uses four core processes: 1) space charge effects, 2) free electron/hole pair recombination, hole-hydrogen defect reactions in the oxides and 4) proton depassivation of dangling bonds at the Si/SiO2 interface. Radiation hardness assurance implications are discussed.

Pease, Ron↗
NASA NTRS1981

Atomic hydrogen rocket engine

A rocket using atomic hydrogen propellant is discussed. An essential feature of the proposed engine is that the atomic hydrogen fuel is used as it is produced, thus eliminating the necessity of storage. The atomic hydrogen flows into a combustion chamber and recombines, producing high velocity molecular hydrogen which flows out an exhaust port. Standard thermodynamics, kinetic theory and wall recombination cross-sections are used to predict a thrust of approximately 1.4 N for a RF hydrogen flow rate of 4 x 10 to the 22nd/sec. Specific impulses are nominally from 1000 to 2000 sec. It is predicted that thrusts on the order of one Newton and specific impulses of up to 2200 sec are attainable with nominal RF discharge fluxes on the order of 10 to the 22nd atoms/sec; further refinements will probably not alter these predictions by more than a factor of two.

Etters, R. D.↗
NASA NTRS1985

Surface and bulk-loss reduction research by low-energy hydrogen doping

Surface and bulk loss reduction by low energy hydrogen doping of silicon solar cells was examined. Hydrogen ions provided a suppression of space charge recombination currents. Implantation of hydrogen followed by the anneal cycle caused more redistribution of boron than the anneal which could complicate processing. It was demonstrated that passivation leads to space charge current reduction.

Fonash, S.↗
NASA NTRS1975

The ground state properties of spin-aligned atomic hydrogen, deuterium, and tritium

The internal energy, pressure, and compressibility of ground-state, spin-aligned atomic hydrogen, deuterium, and tritium are calculated assuming that all pair interactions occur via the atomic triplet (spin-aligned) potential. The conditions required to obtain atomic hydrogen and its isotopes in bulk are discussed; such a development would be of value in propulsion systems because of the light mass and energetic recombination of atomic hydrogen. Results show that atomic triplet hydrogen and deuterium remain gaseous at 0 K, and that tritium forms a liquid with a binding energy of approximately -0.75 K per atom at a molar volume of 130 cu cm per mole. The pair distribution function for these systems is calculated, and the predicted superfluid behavior of atomic triplet hydrogen and tritium is briefly discussed.

Etters, R. D.↗