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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 1,027 records · Page 57
All sourcesNASA NTRSDOE OSTI
NASA NTRS2009

From Michelson and Fizeau to a Space-borne Infrared Instrument Capable of Detecting an Earth Twin: Development and Recent Accomplishments of Stellar Interferometry

In recent years, the evolution of technology has led to significant advances in high angular resolution astronomy and the precision of new observations. In particular, the interferometric combination of light from physically separated telescopes has shown both great promise and great challenge. We describe the first scientific results from the Keck Interferometer Nuller an instrument that combines the light of the two largest optical telescopes in the world in the context of the historic development of interferometry from its beginning in the work of Fizeau, Stephan and Michelson. We also describe our efforts to build a space-borne mid-infrared interferometer the Fourier Kelvin Stellar Interferometer (FKSI) - for the characterization of exoplanets. We report results of a recent engineering study on an enhanced version of FKSI that includes 1-meter primary mirrors, 20-meter boom length, and an advanced sun shield that will provide a 45-degree FOR and 40K operating temperature for all optics, including siderostats, enabling the characterization of exozodiacal debris disks, extrasolar planets and other phenomena requiring extremely high spatial resolution. We are further investigating the possibility of characterizing the atmospheres of several super-Earths and a few Earth twins by a combination of spatial modulation and spectral analysis.

Barry, Richard K.↗
DOE OSTI2025

Sample screening of uranium ore concentrates using portable spectrophotometers: investigating the correlation between visible colors and chemical signatures

A research collaboration between the Japan Atomic Energy Agency and the Department of Energy’s National Nuclear Security Administration examined nuclear forensic signatures and analytical methods for tracing the origins of uranium ore concentrates (UOCs). Here, this study focuses on utilizing portable spectrophotometers capable of reflectance measurements in the visible light spectrum as a potential rapid screening tool for nuclear forensics analysis. Unlike laboratory-based near-infrared spectroscopy or digital image analysis, this research investigated the potential to correlate visible color measurements with key nuclear forensics signatures using seven types of UOC samples with known origins and three UOC certified reference materials. Results demonstrated that distinct color groups, quantified using CIELAB values, correlated with major uranium compounds. Furthermore, the findings indicated that trace elements can influence the UOC colors, providing additional insights into material characteristics. Although this approach requires further validation across a broader range of UOC species, this study demonstrated that simple colorimetric analysis using visible spectrophotometry, which does not require complex sample preparation or data processing, can serve as a practical and novel rapid tool for preliminary screening and attribution in nuclear forensics investigations.

and nuclear chemistry↗
DOE OSTI2024

Microscopic origin of criticality at macroscale in QCD chiral phase transition

We reveal that the criticality of the chiral phase transition in QCD at the macroscale arises from the microscopic energy levels of its fundamental constituents, the quarks. We establish a novel relation between cumulants of the chiral order parameter (i.e., chiral condensate) and correlations among the energy levels of quarks (i.e., eigenspectra of the massless Dirac operator), which naturally leads to a generalization of the Banks-Casher relation. Based on this novel relation and through (2+1)-flavor lattice QCD calculations using the HISQ action with varying light quark masses in the vicinity of the chiral phase transition, we demonstrate that the correlations among the infrared part of the Dirac eigenspectra exhibit same universal scaling behaviors as expected of the cumulants of the chiral condensate. We find that these universal scaling behaviors extend up to the physical values of the up and down quark masses.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

NO 2 -mediated voloxidation for iodine separation from cesium iodide surrogates

Heterogeneous NO 2 -mediated oxidation of uranium, also known as advanced voloxidation, is a proposed head-end reprocessing method for used nuclear fuel. An advantage of advanced voloxidation is the removal of volatile fission products, which complicate downstream separation and containment challenges leading to increased processing economics. Iodine, one of the volatile species of interest, has exhibited varied results in this process. Using CsI as a surrogate material, this work mimics the effect of NO 2 -based voloxidation on iodine and sheds light on the factors that influence the solid–gas phase reaction. Solid-state analysis using Fourier transform infrared attenuated total reflectance spectroscopy and scanning electron microscopy with energy-dispersive X-ray spectroscopy confirmed the conversion of CsI to CsNO 3 . Iodine separation ranged from 46% to 100% across multiple tests. Iodine separation was most effective when multiple recharges of NO 2 were administered. In conclusion, at the bench scale, liberating iodine from CsI appears to occur within 1 h, but the presence of surface H 2 O and the composition of the NO x reagent mixtures greatly influence its success.

advanced voloxidation↗
DOE OSTI2023

Abundances and Transients from Neutron Star–White Dwarf Mergers

Abstract We systematically investigate the mergers of neutron star–white dwarf binaries from beginning to end, with a focus on the properties of the inflows and outflows in accretion disks and their electromagnetic emissions. Using population synthesis models, we determine a subset of these binaries in which the white dwarf companion undergoes unstable mass transfer and complete tidal disruption, forming a large accretion disk around the neutron star. The material evolves according to a one-dimensional advection-dominated accretion-disk model with nuclear burning, neutrino emissions, and disk-surface wind ejection. The extreme dynamics of the entire process have proven difficult to analyze, and thus currently, the properties are poorly understood. The outflows from the mergers are iron- and nickel-rich, giving rise to optical and infrared emissions powered by the decay of the radioactive iron-type isotopes, calculated via the SuperNu light-curve code. We find these systems capable of powering bright, yet short-lived, optical transients with the potential to power gamma-ray bursts.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1974

The nature of Cygnus X-3 - A prototype for old population binary X-ray sources

Description of a model for Cyg X-3 based on a short-lived phase in the evolution of a U Geminorum-type binary where rapid mass transfer and mass loss occurs. X rays are generated by accretion on the white dwarf component, while both stars are enveloped in a thick stellar wind emanating from the red dwarf. Electron scattering in the cloud is responsible for the modulation of the X rays with the orbital period of 4.8 hours. Ultraviolet radiation and low-energy X rays absorbed in the cloud are reradiated in the optical and infrared, which, it is predicted, will display a 4.8-hr modulation in phase with the X-ray light curve. The X-ray absorption cutoff should also vary with phase, appearing at minimum energy when the source is at maximum light. The model also provides a framework in which certain aspects of the associated nonthermal radio source may be understood. Finally, it is suggested that the model may be applicable to Sco X-1 as well.

Davidsen, A.↗
NASA NTRS1977

A saturation model of the atmosphere of Uranus

A model of the atmospheric structure of Uranus is presented which differs from previous types of models in two important respects: (1) the CH4/H2 ratio is sufficiently large that CH4 is saturated to large depths in the Uranian atmosphere and (2) the internal energy flux is small compared with that due to solar heating. Because of the small internal flux, the thermal flux decreases rapidly with depth and the atmosphere is radiative to large optical depths. A CH4 droplet cloud forms where the atmosphere finally becomes convective due to the internal flux. The model is shown to be in reasonable agreement with published observations of the H2 quadrupole 3-0 and 4-0 bands, the visible (4000-6000 A) CH4 bands, and the infrared emission spectrum.

Danielson, R. E.↗
NASA NTRS1986

Camera for Monitoring Vegetation

Video camera uses solid-state imaging devices and light filters to bring out subtle spectral differences between healthy and stressed vegetation differences not readily detectable with infrared film cameras. Camera employs two detector arrays. Video camera made small and easily portable. Eliminates need for refrigeration of film before use, and provides instantaneous output with no delay for film development.

Martin, T. Z.↗
NASA NTRS1987

The early spectral phase of type Ib supernovae - Evidence for helium

A near-infrared spectrum and several optical spectra of SN 1983N obtained over a period from 10 days before maximum light to about a week after maximum and of SN 1984L from about maximum light to about 60 days later are presented. On the basis of these spectra it is argued that the first definite identification of helium in supernova ejecta near maximum light has been made. The emergence of oxygen emission lines which presage the dramatic transition to the supernebular phase is identified. Supernova atmosphere models which are consistent with the observations are presented, and it is argued that a strong departure of helium level populations from LTE is necessary. The current status of SNe Ib, the arguments that they result from core collapse in moderately massive stars, and some of the immediate work necessary to further clarify the nature of these events are summarized.

Harkness, R. P.↗
NASA NTRS1987

The scatterometer for DIRBE

A scatterometer for monitoring the performance degradation of an infrared instrument in the Diffuse Infrared Background Experiment (DIRBE) due to contamination of the primary mirror is described. The scatterometer monitors the scattered light from an off-axis internal source to provide a measure of the integrity of the optical system. Preliminary results indicate that the measured BRDF of the primary mirror is two orders of magnitude worse than the specification, and thus may be unacceptable.

Bolton, John F.↗
NASA NTRS1988

The high-latitude F supergiant IRAS 18095 + 2704 - A proto-planetary nebula

The paper reports the discovery of a new high-latitude F supergiant, IRAS 18095 + 2704, which shows a large excess in the far-infrared. Ground-based observations have identified it as a V = 10.4 mag F3 Ib star which displays light and velocity variability. Comparison with the post-asymptotic giant branch (AGB) evolution model of Volk and Kwok suggests that it is an excellent candidate for a protoplanetary nebula. Model fitting of the spectrum of 18095 + 2704 from 0.35 to 100 microns suggests that it evolved from the AGB approximately 265 yr ago and had a mass-loss rate of 0.00003 solar mass/yr at the end of the AGB.

Hrivnak, Bruce J.↗
NASA NTRS1994

MODIS airborne simulator visible and near-infrared calibration, 1992 ASTEX field experiment. Calibration version: ASTEX King 1.0

Calibration of the visible and near-infrared (near-IR) channels of the MODIS Airborne Simulator (MAS) is derived from observations of a calibrated light source. For the 1992 Atlantic Stratocumulus Transition Experiment (ASTEX) field deployment, the calibrated light source was the NASA Goddard 48-inch integrating hemisphere. Tests during the ASTEX deployment were conducted to calibrate the hemisphere and then the MAS. This report summarizes the ASTEX hemisphere calibration, and then describes how the MAS was calibrated from the hemisphere data. All MAS calibration measurements are presented and determination of the MAS calibration coefficients (raw counts to radiance conversion) is discussed. In addition, comparisons to an independent MAS calibration by Ames personnel using their 30-inch integrating sphere is discussed.

Arnold, G. Thomas↗
NASA NTRS2001

Real-time measurements of endogenous CO production from vascular cells using an ultrasensitive laser sensor

Carbon monoxide (CO) has been implicated as a biological messenger molecule analogous to nitric oxide. A compact gas sensor based on a midinfrared laser absorption spectroscopy was developed for direct and real-time measurement of trace levels (in approximate pmol) of CO release by vascular cells. The midinfrared light is generated by difference frequency mixing of two nearinfrared lasers in a nonlinear optical crystal. A strong infrared absorption line of CO (4.61 microm) is chosen for convenient CO detection without interference from other gas species. The generation of CO from cultured vascular smooth muscle cells was detected every 20 s without any chemical modification to the CO. The sensitivity of the sensor reached 6.9 pmol CO. CO synthesis was measured from untreated control cells (0.25 nmol per 10(7) cells/h), sodium nitroprusside-treated cells (0.29 nmol per 10(7) cells/h), and hemin-treated cells (0.49 nmol per 10(7) cells/h). The sensor also detected decreases in CO production after the addition of the heme oxygenase (HO) inhibitor tin protoporphyrin-IX (from 0.49 to 0.02 nmol per 10(7) cells/h) and increases after the administration of the HO substrate hemin (from 0.27 to 0.64 nmol per 10(7) cells/h). These results demonstrate that midinfrared laser absorption spectroscopy is a useful technique for the noninvasive and real-time detection of trace levels of CO from biological tissues.

Non-NASA Center↗
NASA NTRS2003

High-Temperature Sprayable Phosphor Coating Developed for Measuring Surface Temperatures

The use of phosphor thermography for noncontact temperature measurements in harsh environments has been proven over the last decade, but it has suffered from difficult application procedures such as vapor deposition or sputtering techniques. We have developed a high-temperature-sensitive paint that is easily applied with commercially available paint-spraying equipment and have successfully demonstrated it to temperatures up to 1500 C. Selected phosphors have also shown measurable signals to 1700 C, thus allowing a combination of phosphors to be used in high-temperature binders to make surface temperature measurements from ambient to over 1500 C. Phosphor thermography is an optical technique that measures the time response of fluorescence light, which is a function of the phosphor temperature. The phosphors are excited with short wavelength light (ultraviolet or blue), and they emit light at a longer wavelength. This technique has a benefit over other temperature measurements, such as thermocouples and infrared thermography, in difficult environments such as high blackbody backgrounds, vibration, flames, high electromagnetic noise, or where special windows may be needed. In addition, the sprayable phosphor paints easily cover large or complicated structures, providing full-surface information with a single measurement. Oak Ridge National Laboratories developed and tested the high-temperature binders and phosphors under the direction of the NASA Glenn Research Center. Refractory materials doped with rare earth metals were selected for their performance at high temperature. Survivability, adhesion, and material compatibility tests were conducted at high temperatures in a small furnace while the fluorescent response from the phosphors was being measured. A painted sample in a furnace with a clearly visible fluorescing dot excited by a pulsed laser is shown. Measuring the decay time of this fluorescence yields the surface temperature. One new paint was recently tested in a rocket test stand at Glenn. The floor of a square duct nozzle was painted, and full-field lifetime decay measurements were acquired for multiple firings of the rocket. Good agreement with predicted results was obtained, matching temperature gradients along the length of the nozzle and clearly showing shock structures. These good results were very satisfactory given that the measurements were made looking through the combustion plume. Infrared pyrometry was incapable of making the surface measurements because of the interference from the rocket exhaust, which contaminated the infrared signature.

Bencic, Timothy J.↗
NASA NTRS2013

Single-Photon-Sensitive HgCdTe Avalanche Photodiode Detector

The purpose of this program was to develop single-photon-sensitive short-wavelength infrared (SWIR) and mid-wavelength infrared (MWIR) avalanche photodiode (APD) receivers based on linear-mode HgCdTe APDs, for application by NASA in light detection and ranging (lidar) sensors. Linear-mode photon-counting APDs are desired for lidar because they have a shorter pixel dead time than Geiger APDs, and can detect sequential pulse returns from multiple objects that are closely spaced in range. Linear-mode APDs can also measure photon number, which Geiger APDs cannot, adding an extra dimension to lidar scene data for multi-photon returns. High-gain APDs with low multiplication noise are required for efficient linear-mode detection of single photons because of APD gain statistics -- a low-excess-noise APD will generate detectible current pulses from single photon input at a much higher rate of occurrence than will a noisy APD operated at the same average gain. MWIR and LWIR electron-avalanche HgCdTe APDs have been shown to operate in linear mode at high average avalanche gain (M > 1000) without excess multiplication noise (F = 1), and are therefore very good candidates for linear-mode photon counting. However, detectors fashioned from these narrow-bandgap alloys require aggressive cooling to control thermal dark current. Wider-bandgap SWIR HgCdTe APDs were investigated in this program as a strategy to reduce detector cooling requirements.

Huntington, Andrew↗
NASA NTRS1972

Nondispersive infrared analyzer for specific gases in complex mixtures

Analyzer identifies and measures particular diatomic or polyatomic gases in complex gas mixtures. Mixing of absorption effects on light energy passing through gases to photodetector produces a signal component that is related to the absorption caused by reference-gas component in unknown gas mixture.

Dimeff, J.↗
NASA NTRS1993

Correcting for diffraction in the far-infrared reflectance measurement of rough surfaces

The manner in which diffraction can increase the reflectance measured from very rough surfaces is shown by observations of diffracted light within the instrument profile of a far-IR reflectometer system. A correction to the calibration signal based on numerical integration of the diffracted part of the instrument profile is described. Diffraction correction factors as large as 2.94 have been found with small optics at long wavelength (630 microns). The effect of diffraction on diffuse reflectance measurements of a very rough perfect reflector is shown at wavelengths from 56 to 200 microns.

Smith, Sheldon M.↗