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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

An optical model for composite nuclear scattering

The optical model of composite particle scattering is considered and compared to the accuracies of other models. A nonrelativistic Schroedinger equation with two-body potentials is used for the scattering of a single particle by an energy-dependent local potential. The potential for the elastic channel is composed of matrix elements of a single scattering operator taken between the ground states of the projectile and the target; the coherent amplitude is considered as dominating the scattering in the forward direction. A multiple scattering series is analytically explored and formally summed by the solution of an equivalent Schroedinger equation. Cross sections of nuclear scattering are then determined for He-4 and C-12 nuclei at 3.6 GeV/nucleus and O-16 projectiles at 2.1 GeV/nucleus, and the optical model approximations are found to be consistently lower and more accurate than approximations made by use of Glauber's theory.

Wilson, J. W.↗
NASA NTRS1985

Cracked shaft detection on large vertical nuclear reactor coolant pump

Due to difficulty and radiation exposure associated with examination of the internals of large commercial nuclear reactor coolant pumps, it is necessary to be able to diagnose the cause of an excessive vibration problem quickly without resorting to extensive trial and error efforts. Consequently, it is necessary to make maximum use of all available data to develop a consistent theory which locates the problem area in the machine. This type of approach was taken at Three Mile Island, Unit #1, in February 1984 to identify and locate the cause of a continuously climbing vibration level of the pump shaft. The data gathered necessitated some in-depth knowledge of the pump internals to provide proper interpretation and avoid misleading conclusions. Therefore, the raw data included more than just the vibration characteristics. Pertinent details of the data gathered is shown and is necessary and sufficient to show that the cause of the observed vibration problem could logically only be a cracked pump shaft in the shaft overhang below the pump bearing.

Jenkins, L. S.↗
NASA NTRS1975

Cardiovascular Imaging and Image Processing: Theory and Practice - 1975

Ultrasonography was examined in regard to the developmental highlights and present applicatons of cardiac ultrasound. Doppler ultrasonic techniques and the technology of miniature acoustic element arrays were reported. X-ray angiography was discussed with special considerations on quantitative three dimensional dynamic imaging of structure and function of the cardiopulmonary and circulatory systems in all regions of the body. Nuclear cardiography and scintigraphy, three--dimensional imaging of the myocardium with isotopes, and the commercialization of the echocardioscope were studied.

Harrison, Donald C.↗
NASA NTRS1991

Nonlinear behavior of solar gravity modes driven by He-3 in the core. II - Numerical simulations

The nonlinear behavior of gravity-mode oscillations driven by He-3-destroying reactions in the solar core has been examined by numerically integrating equations describing a very simplified model. The results of a previous bifurcation analysis, which suggest that such oscillations are unlikely to attain amplitudes sufficient to trigger core convection, are verified. These results are extended to models whose nuclear reaction rates and thermal stratification represent the core somewhat more accurately. Nonlinear processes give rise to a preference for the oscillations to develop as standing waves rather than traveling waves, thus breaking the degeneracy between these two types of motion which exists in linearized theory. Study of the large-amplitude behavior of the oscillations is hindered by a tendency for the model to become thermally unstable.

Merryfield, William J.↗
NASA NTRS2003

New Experiments with Spinning Metallic Discs

A number of recent advanced theories related to torsion properties of the space-time matrix predict the existence of an interaction between classically spinning objects. Indeed, some experimental data suggest that spinning magnetic bodies discernibly interact with Earth's natural fields. If there are interactions between rotating bodies then nuclear spins could be used for detection. Thus, assuming a spinning body induces a hypothetical torsion field, a sensor based on the giant magnetoresistance effect would detect local changes. Experimentally, spinning a brass wheel shielded from Earth's magnetic field showed no measurable change in signals; with no shielding a Faraday disc phenomenon was observed. Unexpected experimental measurements from the non-axial Faraday disc configuration were recorded and a theoretical model was derived to explain them.

Mazuruk, Konstantin↗
NASA NTRS2008

Chromosome Aberration in Human Blood Lymphocytes Exposed to Energetic Protons

During space flight, astronauts are exposed to a space radiation consisting of high-energy protons, high charge and energy (HZE) nuclei, as well as secondary particles that are generated when the primary particles penetrate the spacecraft shielding. Secondary particles have a higher LET value than primary protons and therefore expected to have a higher relative biological effectiveness (RBE). To investigate this theory, we exposed human peripheral blood lymphocytes to protons with energies of 250 MeV, 800MeV, 2 GeV, or 2.5 GeV. LET values for these protons ranged from 0.4 to 0.2 keV/micrometer. and doses ranged from 0.2 to 3 Gy. Over this energy the probability of nuclear reaction leading to secondary radiation, and the multiplicity of reaction produces such as neutrons and mesons increases substantially. The effect of aluminum and polyethylene shielding was also assessed using the 2 GeV and 2.5GeV proton beams. After exposure lymphocytes were stimulated to divide and chromosomes were collected from cells in the first G2 and metaphase cell cycle after exposure using a chemical induced premature chromosome condensation (PCC) technique. Dose response data for chromosome damage was analyzed using the fluorescence in situ hybridization (FISH) chromosome painting technique. Selected samples were also analyzed with multicolor FISH (mFISH) and multicolor banding FISH (mBAND) techniques. Data indicates that the dose response for simple-type exchanges is similar for proton and gamma exposure, whereas protons induce higher yields of complex exchanges that are LET dependent. RBE values will be presented for each proton energy, and the effects of shielding and possible cytogenetic signatures of proton exposure will be discussed.

Hada, M.↗
NASA NTRS2014

Low Energy Nuclear Reaction Aircraft- 2013 ARMD Seedling Fund Phase I Project

This report serves as the final written documentation for the Aeronautic Research Mission Directorate (ARMD) Seedling Fund's Low Energy Nuclear Reaction (LENR) Aircraft Phase I project. The findings presented include propulsion system concepts, synergistic missions, and aircraft concepts. LENR is a form of nuclear energy that potentially has over 4,000 times the energy density of chemical energy sources. It is not expected to have any harmful emissions or radiation which makes it extremely appealing. There is a lot of interest in LENR, but there are no proven theories. This report does not explore the feasibility of LENR. Instead, it assumes that a working system is available. A design space exploration shows that LENR can enable long range and high speed missions. Six propulsion concepts, six missions, and four aircraft concepts are presented. This report also includes discussion of several issues and concerns that were uncovered during the study and potential research areas to infuse LENR aircraft into NASA's aeronautics research.

Wells, Douglas P.↗
NASA NTRS1978

Atomic electron correlation in nuclear electron capture

The effect of electron-electron Coulomb correlation on orbital electron capture by the nucleus was treated by the multiconfigurational Hartree-Fock approach. The theoretical Be-7 L/K capture ratio was found to be 0.086, and the Ar-37 M/L ratio, 0.102. Both ratios were smaller than the independent particle predictions. Measurements exist for the Ar M/L ratio, and agreement between theory and experiment was excellent.

Chen, M. H.↗
NASA NTRS1974

Study, selection, and preparation of solid cationic conductors

Crystal chemical principles and transport theory have been used to predict structures and specific compounds which might find application as solid electrolytes in rechargeable high energy and high power density batteries operating at temperatures less than 200 C. Structures with 1-, 2-, and 3-dimensional channels were synthesized and screened by nuclear magnetic resonance, dielectric loss, and conductivity. There is significant conductivity at room temperature in some of the materials but none attain a level that is comparable to beta-alumina. Microwave and fast pulse methods were developed to measure conductivity in powders and in small crystals.

Roth, W. L.↗
NASA NTRS1979

The challenge of detecting gravitational radiation is creating a new chapter in quantum electronics: Quantum nondemolition measurements

Future gravitational wave antennas will be approximately 100 kilogram cylinders, whose end-to-end vibrations must be measured so accurately (10 to the -19th power centimeters) that they behave quantum mechanically. Moreover, the vibration amplitude must be measured over and over again without perturbing it (quantum nondemolition measurement). This contrasts with quantum chemistry, quantum optics, or atomic, nuclear, and elementary particle physics where measurements are usually made on an ensemble of identical objects, and care is not given to whether any single object is perturbed or destroyed by the measurement. Electronic techniques required for quantum nondemolition measurements are described as well as the theory underlying them.

Braginsky, V. B.↗
NASA NTRS1988

An investigation of transitional management problems for the NSTS at NASA, executive summary

A summary is given of the work of the University of Houston research team for the third quarter of effort in a yearly grant for the National Space Transportation System (NSTS). As such it serves as a resting place for the ideas and concepts developed this quarter with the collaboration of the Management Integration Offices of NASA. Another objective is the hope that the report will help to stimulate the healthy problem solving process already present at NASA. The main goal of the contractual work is to help NASA to find ways and means of moving into a truly operational era with the shuttle program. This work is a continuation of early work and the reader is encouraged to read the final reports of earlier years. Chapter One of the report is an introduction. Chapter Two deals with industrial adaptation and is in two parts: theory and application. In the theory section, impressions of the management system immediately after reflight are discussed. A key issue, in the author's opinion is the seeming lack of purpose of the program. The application section has six appendices: 1988 Demographic Survey, Field Notes of Interview with HL/P South Texas Nuclear Project, a comparison of the Agendas of the current manager with that of a previous manager, a note on compartmentalization to assist in manifesting, a study on launch prediction for STS-26, and a discussion of a statistical decision-making course for upper level managers. Chapter Three deals with theoretical results returned on flow shop scheduling which will be of use downstream. Chapter Four deals with a statistical model developed to predict the flight rate in future years and indicates the program will have trouble making its schedule. Chapter Five covers the constructural effort and shows the work to be on schedule.

Hunsucker, John↗
NASA NTRS1994

Physical Theories of Winds From Cool Stars

Cool stars in the late stages of their evolution generally lose mass at a prodigious rate. This includes low mass stars on the red giant branch, on the asymptotic giant branch, and those transiting from the asymptotic giant branch to the planetary nebula phase, as well as massive supergiants. All of these objects are surrounded by dense circumstellar gas and often dust envelopes. This mass loss is an important source of gas and dust for the interstellar medium. For some of these objects, the mass loss rate exceeds the nuclear burning rate and, hence, mass loss determines the subsequent evolution of the star. A variety processes have been invoked to explain the mass loss of these objects. A consensus has developed over the last decade: photospheric processes create an extended atmosphere which extends to several stellar radii. At this height above the photosphere, dust grains can form and radiation pressure drives the dust out. The gas is dragged along by friction. While the detailed processes involved, in particular those lifting the atmosphere, may differ from object to object, this paradigm seems applicable to all of these objects. The process of mass loss breaks up into three parts: 1) The formation of the extended atmosphere; 2) the nucleation and condensation of dust; and 3) The radiation pressure driven wind. Each of these processes will be discussed with an emphasis on those processes that play a role in the mass loss from asymptotic giant branch stars for which the most detailed theories have been developed.

Tielens, A. G. G. M.↗
NASA NTRS1999

A Preliminary Model for Spacecraft Propulsion Performance Analysis Based on Nuclear Gain and Subsystem Mass-Power Balances

A preliminary model for spacecraft propulsion performance analysis based on nuclear gain and subsystem mass-power balances are presented in viewgraph form. For very fast missions with straight-line trajectories, it has been shown that mission trip time is proportional to the cube root of alpha. Analysis of spacecraft power systems via a power balance and examination of gain vs. mass-power ratio has shown: 1) A minimum gain is needed to have enough power for thruster and driver operation; and 2) Increases in gain result in decreases in overall mass-power ratio, which in turn leads to greater achievable accelerations. However, subsystem mass-power ratios and efficiencies are crucial: less efficient values for these can partially offset the effect of nuclear gain. Therefore, it is of interest to monitor the progress of gain-limited subsystem technologies and it is also possible that power-limited systems with sufficiently low alpha may be competitive for such ambitious missions. Topics include Space flight requirements; Spacecraft energy gain; Control theory for performance; Mission assumptions; Round trips: Time and distance; Trip times; Vehicle acceleration; and Minimizing trip times.

Chakrabarti, Suman↗
NASA NTRS1978

Atomic electron correlation in nuclear electron capture

The effect of electron-electron Coulomb correlation on orbital-electron capture by the nucleus has been treated by the multiconfigurational Hartree-Fock approach. The theoretical Be-7 L/K capture ratio is found to be 0.086, and the Ar-37 M/L ratio, 0.102. Both ratios are smaller than the independent-particle predictions. Measurements exist for the Ar M/L ratio, and agreement between theory and experiment is excellent.

Chen, M. H.↗
NASA NTRS1976

Analysis of nuclear induced plasmas

A kinetic model is developed for a plasma generated by fission fragments, and the results are employed to study He plasma generated in a tube coated with fissionable material. Because both the heavy particles and electrons play important roles in creating the plasma, their effects are considered simultaneously. The calculations are carried out for a range of neutron fluxes and pressures. In general, the predictions of the theory are in good agreement with available intensity measurements. Moreover, the theory predicts the experimentally measured inversions. However, the calculated gain coefficients are such that lasing is not expected to take place in a helium plasma generated by fission fragments.

Deese, J. E.↗
NASA NTRS1976

Analysis of nuclear induced plasmas

A kinetic model is developed for a plasma generated by fission fragments and the results are employed to study He plasma generated in a tube coated with fissionable material. Because both the heavy particles and electrons play important roles in creating the plasma, their effects are considered simultaneously. The calculations are carried out for a range of neutron fluxes and pressures. In general, the predictions of the theory are in good agreement with available intensity measurements. Moreover, the theory predicts the experimentally measured inversions. However, the calculated gain coefficients are such that lasing is not expected to take place in a helium plasma generated by fission fragments.

Deese, J. E.↗
NASA NTRS1979

Nuclear Science Symposium, 25th, and Symposium on Nuclear Power Systems, 10th, Washington, D.C., October 18-20, 1978, Proceedings

Detectors of various types are discussed, taking into account drift chambers, calorimetry, multiwire proportional chambers, signal processing, the use of semiconductors, and photo/optical applications. Circuits are considered along with instrumentation for space, nuclear medicine instrumentation, data acquisition and systems, environmental instrumentation, reactor instrumentation, and nuclear power systems. Attention is given to a new approach to high accuracy gaseous detectors, the current status of electron mobility and free-ion yield in high mobility liquids, a digital drift chamber digitizer system, the stability of oxides in high purity germanium, the quadrant photomultiplier, and the theory of imaging with a very limited number of projections.

Source record↗
NASA NTRS1984

Theory of the spin-1 bosonic liquid metal - Equilibrium properties of liquid metallic deuterium

The theory of a two-component quantum fluid comprised of spin-1/2 fermions and nonzero spin bosons is examined. This system is of interest because it embodies a possible quantum liquid metallic phase of highly compressed deuterium. Bose condensation is assumed present and the two cases of nuclear-spin-polarized and -unpolarized systems are considered. A significant feature in the unpolarized case is the presence of a nonmagnetic mode with quadratic dispersion owing its existence to nonzero boson spin. The physical character of this mode is examined in detail within a Bogoliubov approach. The specific heat, bulk modulus, spin susceptibility, and thermal expansion are all determined. Striking contrasts in the specific heats and thermal-expansion coefficients of the liquid and corresponding normal solid metallic phase are predicted.

Oliva, J.↗