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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Integration of a 6 LilnSe 2 thermal neutron detector into a CubeSat instrument

This paper describes the development of a preliminary compact and lightweight neutron detection system that uses the low power consuming CubeSat platform and will be especially effective for space-based applications. This is made possible using the novel 6 LiInSe 2 scintillator crystal and a silicon avalanche photodiode (Si-APD). The schematics of this instrument are presented as well as the response of the instrument to initial testing under alpha radiation. The entire system weighs 670 grams and requires 5 volts direct current at 3 watts.

36 MATERIALS SCIENCE↗
DOE OSTI2010

Growth and crystal structure of binary molybdate CsFe(MoO{sub 4}){sub 2}

CsFe(MoO{sub 4}){sub 2} single crystals have been grown by solution-melt crystallization with a charge-to-solvent ratio of 1: 3 (with Cs{sub 2}Mo{sub 3}O{sub 10} used as a solvent). The crystal structure of this compound has been refined by X-ray diffraction (X8 APEX automatic diffractometer, MoK{sub {alpha}} radiation, 356 F(hkl), R = 0.0178). The trigonal unit cell has the following parameters: a = b = 5.6051(2) A, c = 8.0118(4) A, V = 217.985(15) A{sup 3}, Z = 1, {rho}{sub calc} = 3.875 g/cm{sup 3}, and sp. gr. P3-barm1. The structure is composed of alternating layers of FeO{sub 6} octahedra (with MoO{sub 4} tetrahedra attached by sharing vertices) and CsO{sub 12} icosahedra.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2011

Refinement of the composition and structure of YBaCo{sub 4-x}Al{sub x}O{sub 7+{delta}} crystals

YBa(Co{sub 4-x}Al{sub x})O{sub 7+{delta}} (114Y) crystals have been grown in the Y-Ba-Co-O system by spontaneous crystallization from a slowly cooled nonstoichiometric melt. To change the oxygen content, the crystals were isothermally annealed in air in the range of 280-490 Degree-Sign C. The crystals grown were characterized by scanning electron microscopy and powder X-ray diffraction. According to the data of an X-ray spectroscopic quantitative microprobe analysis, the average compositions of 'as-grown' and oxygen-saturated crystals were Y{sub 1.04}Ba{sub 1}Co{sub 3.54}Al{sub 0.50}O{sub 7.8} and Y{sub 1.02}Ba{sub 1}Co{sub 3.55}Al{sub 0.51}O{sub 8.4}, respectively. The refinement of the crystal structure after saturation on an automatic Bruker X8APEX diffractometer with a CCD detector (MoK{alpha} radiation, graphite monochromator, {theta}{sub max} = 32.54 Degree-Sign , sp. gr. P6{sub 3}mc, a = 6.2746(9), c = 10.257(3) Angstrom-Sign , V = 349.71(13) Angstrom-Sign {sup 3}, Z = 2, d{sub calcd} = 5.220 g/cm{sup 3}) reveals the location of Al in two independent positions of Co atoms and yields the general formula of the compound as YBaCo{sub 3.26}Al{sub 0.74}O{sub 7}. Problems related to the difference in the compositions obtained by different methods are discussed.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2010

P[subscript H2O]-dependent structural phase transitions in the zeolite mesolite: Real- and reciprocal-space crystal structure refinements

The response of the mesolite crystal structure (Na{sub 16}Ca{sub 16}Al{sub 48}Si{sub 72}O{sub 240}{center_dot}64H{sub 2}O) to dehydration was evaluated as a function of temperature and partial pressure of water (i.e., P{sub H{sub 2}O} or relative humidity, RH) using laboratory X-ray powder diffraction (XRD; CuK{sub {alpha}} radiation) and synchrotron X-ray pair distribution function (PDF) methods. At 425 C under low-P{sub H{sub 2}O} conditions (P{sub H{sub 2}O} {le} {approx}1.3 mbar), dehydrated mesolite preserved the long-range ordered aluminosilicate framework structure, which has not been previously observed. This new dehydrated phase, x-metamesolite, has unit-cell parameters [a = 16.731(3) {angstrom}, b = 17.822(2) {angstrom}, c = 6.312(1) {angstrom}, V = 1882.5(5) {angstrom}{sup 3}, and possible space group Fdd2] similar to those of other dehydrated natrolite phases (either 1- or 2-metanatrolite). Conversely, under high-P{sub H{sub 2}O} conditions (P{sub H{sub 2}O} > {approx}1.3 mbar), dehydrated mesolite became amorphous (amorphous T{sub 5}O{sub 10}) at 425 C. The local structure of amorphous T{sub 5}O{sub 10} was characterized by PDF analyses, which showed the formation of twisted T{sub 5}O{sub 10} nano-fibers [with dimensions (LWH) of {approx}6.9 x 6.9 x 6.3 {angstrom}] resulting from breakage of the mesolite aluminosilicate framework. The two distinct high-temperature P{sub H{sub 2}O}-dependent phase transition paths illustrate the importance of considering the combined effects of temperature and P{sub H{sub 2}O} in mesolite. In addition, the low-temperature phase transition in mesolite, involving order-disorder of the extraframework cations, also showed a P{sub H{sub 2}O}-dependent transition temperature. Although, there is no path dependence on P{sub H{sub 2}O} for this transition, the local arrangement of Na, Ca, and vacancies in disordered metamesolite (formed through the extraframework cation order-disorder phase transition) likely influences the thermal stability of the aluminosilicate framework during further heating.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Evaluation of Hydrogen Gas Generation and Permeation in the 9979 Type AF Shipping Package

The 9979 Type AF Shipping Packaging is a cost-effective radioactive material package designed by Savannah River National Laboratory (SRNL) that consists of two primary components: a foamed outer drum for structural protection and an inner containment drum. The packaging was designed to transport Highly Enriched Uranium (HEU), Low Enriched Uranium (LEU), and other isotopes not exceeding a Type A quantity. These contents have the potential to generate flammable hydrogen gas during transport due to the degradation of hydrogenous materials (e.g. water vapor, plastics, etc) by high-energy alpha radiation. Since 10 CFR 71.43(h) prohibits the incorporation of packaging features explicitly designed for continuous venting, alternative justification was required to demonstrate that the requirements of 10 CFR 71.43(d) for negligible reactions between packaging components and contents were satisfied. An analysis was performed to demonstrate that the potential for hydrogen gas generation over a one-year period was limited by the effects of permeation through the packaging materials. The rate of hydrogen collection was evaluated for both the inner containment drum and the outer structural drum under 10 CFR 71.71 Normal Conditions of Transport (NCT). The analysis concludes that the Lower Flammability Limit (LFL) for hydrogen gas will not be reached in a one-year shipping period assuming a minimum void volume is maintained within the drum.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2021

Comparing elemental measurements at packaging and after storage for signatures of chloride salt radiolysis

Radiolysis of hydrated alkaline earth chloride salts by alpha radiation from plutonium produces the chloride containing gases HCl and Cl 2 . These gases are known to diffuse out of the plutonium-containing material and contribute to corrosion outside of the convenience container. The alkaline earth elements remain with the plutonium-containing material as oxides or hydroxides. The amount of chlorine within the material after storage will be reduced compared to the amount at packaging. The fraction of the alkaline earth elements that are soluble after storage will be reduced compared to the amount at packaging. These signatures may be observable by comparing the chemical analysis measurements made at packaging and after storage. Comparison of measurements on a single Hanford container shows that the chloride does decrease and the alkaline earth elements have reduced solubility in water. Differences seen with other elements make conclusions difficult.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2024

Production of Astatine-211 for Translational Science in Radiotherapy (Research Performance Progress Report)

In this proposal we outline the methods to improve the isotope production of astatine-211 at the University of Pennsylvania Cyclotron Facility. Astatine-211 is an isotope that emits alpha- radiation and has high potential for treating otherwise untreatable cancers. The goal of this proposal is two fold, 1) Optimize current production of astatine-211 and maintain routine production and 2) develop new isotope production target systems and chemical isolation systems. By completing this proposal we will ensure that the University of Pennsylvania Cyclotron Facility continues to build it’s isotope program in an effort that unites under DOE isotope network supply initiatives with the overall goal of increasing the national supply of isotopes. The University of Pennsylvania is uniquely located in the northeast corridor of the United States of America and has access to dozens of institutions that could use astatine-211 in their research. With the support of the DOE we have the opportunity to provide additional momentum to this growing field of research and will be able to provide the foundation for economical development of astatine-211 research and application in medicine.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
NASA NTRS1969

A hydrogen bulge over the springtime pole.

Hydrogen bulge above springtime pole indicated by Lyman alpha radiation in earth geocorona, discussing hydrogen horizontal transport and hydrogen compounds dissociation as causes

Donahue, T. M.↗
NASA NTRS1971

Rocket measurements of ion and electron densities in the D- and lower E-regions near sunrise

Positive-ion and electron densities were measured in the 75 to 110 km altitude range with the aid of two rockets launched from White Sands near sunrise. The solar zenith angles were 91 and 79 deg respectively. The densities were derived from measurements made by an ion collector and from data obtained with a Faraday rotation technique capable of detecting electrons in the D-region. It has been found that in the 80-95 km altitude range, electron detachment from negative ions takes place mainly at zenith angles of less than 91 deg. The source of the high positive-ion density (N(+) approximately 700/cu cm) at an altitude of 75 km just before sunrise is presumed to be scattered Lyman alpha radiation which is ionizing nitric oxide.

Pedersen, A.↗
NASA NTRS1970

An investigation of the ionospheric D region at sunrise

The growth over sunrise of the C and D layers of the ionosphere is investigated. The model which is analyzed includes the negative ion species O(-), O2(-), O3(-), O4(-), NO3(-), CO3(-), and CO4(-). Ionization sources due to galactic cosmic rays, precipitated electrons, ionization of NO by scattered Lyman alpha radiation, and the direct solar radiation ionization are also included. The photodetachment of most of the negative ions is discussed, as well as the time variation of these parameters. The time variations of the electron, negative ion, and positive ion densities are calculated over sunrise. From these data, the mesospheric C and D layer development is plotted. Several model parameters are varied until the best agreement with experimentally determined electron densities is obtained. The results are discussed in light of several atmospheric parameters including the O and NO concentrations and the electron-ion recombination coefficient.

Turco, R. P.↗
NASA NTRS1972

Equatorial ionospheric absorption during half a solar cycle (1964-1970)

An extensive series of vertical incidence absorption measurements made at an equatorial station is analyzed in detail for a better understanding of the lower ionosphere. A quantitive empirical relationship is derived between absorption and 1 to 8 A solar flux for moderate levels of solar activity. It is shown that the threshold flux for D region modification, at a solar zenith angle of 10 deg, is approximately 0.0005 erg/sq/cm/sec. Attention is drawn to the incidence of days of high absorption even in the absence of solar X-ray activity. Available evidence points to variability of the order of 10 to 40% in the intensity of the solar Lyman alpha radiation as the most likely cause of these unusual, though infrequent, enhancements in absorption.

Gnanalingam, S.↗
NASA NTRS1971

Studies of positive-ion composition in the equatorial D-region ionosphere.

Evaluation of two daytime D-region positive-ion composition measurements performed at Thumba, India, for solar zenith angles of 53.2 and 27.8 deg. Comparison of upleg ram with downleg wake data shows a large increase in the concentration of heavy ions 48(+), NO(+) . H2O; 55(+), H3O(+) . (H2O)2; and M(+) greater than 65(+) for the downleg reduced shock condition. Peak concentrations of 48(+) and 55(+) occur at unit optical depth for Lyman alpha radiation. The ion 37(+), H3O(+) . H2O, is dominant for chi = 27.8 deg, but not for chi = 53.2 deg, consistent above 80 km with an origin from the X-ray production of O2(+). Laboratory measurements have shown that the ion, NO(+), can be transferred to heavy hydrates 48(+), 55(+), and M(+) greater than 65(+) by a reaction chain starting with NO(+) + X + M = NO(+) . X + M, where X can be O2, N2, CO2 or a combination of all three, depending on the rate of reaction. This chain, together with a similar reaction scheme starting with O2(+) and ending in 19(+), 37(+), and heavier clusters, is used to provide a consistent explanation for the hydrated ions observed in the D region.

Goldberg, R. A.↗
NASA NTRS1972

Glauber calculations of polarization of Lyman-alpha resulting from e/-/-H/1s/ collisions.

We have calculated the polarization fraction of the Lyman-alpha radiation emitted in e/-/-H/1s/ collisions using the Glauber, Born, and various Vainshtein approximations, and have compared these predictions with observation. We find that the Born, Glauber and all forms of the Vainshtein yield results which are very close to each other and to the data in the energy range from 30 to 700 eV. The comparatively small differences between the various approximations are detailed in the text; also, the reason for the close agreement of the predicted polarization fractions - although the computed 1s-2p total and differential cross sections are not so close - is explained. With respect to the Glauber approximation, the importance of computing the phase integral along a direction perpendicular to the momentum transfer q at each value of q, is stressed.

Gerjuoy, E.↗