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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 1,423 records · Page 79
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Automated Algorithms for Screening Electronic Parts for Aging using Power Spectra Analysis (PSA) Data

Understanding the age of semiconductor parts being built into devices and systems is of interest for manufacturing quality control. Power spectrum analysis (PSA) is a fast, non-destructive, sensitive method for examining semiconductor parts. This talk will cover the use of multivariate analysis on both PSA data and conventional current-voltage data generated prior to PSA analysis to create algorithms that can be automated to screen semiconductor parts for aging.

Multari, Rosalie A↗
NASA NTRS1975

Thermal control of power supplies with electronic packaging techniques

The analysis, design, and development work to reduce the weight and size of a standard modular power supply with a 350 watt output was summarized. By integrating low cost commercial heat pipes in the redesign of this power supply, weight was reduced by 30% from that of the previous design. The temperature was also appreciably reduced, increasing the environmental capability of the unit. A demonstration unit with a 100 watt output and a 15 volt regulator module, plus simulated output modules, was built and tested to evaluate the thermal performance of the redesigned power supply.

Source record↗
NASA NTRS1980

Study of intermittent field hardware failure data in digital electronics

The collection and analysis of data concerning intermittent dailures in digital devices was performed using data from a computer design for shipboard usage. The failure data consisted of actual field failures classified by failure mechanisms and their likelihood of having been intermittent, potentially intermittent, or hard. Each class was studies with respect to computer operation in the ranges of 0 to 2,000 hours, 0 to 5, hours, and 0 to 10,000 hours. The study was done at the computer level as well as the microcircuit level. Results indicate that as age increases, the quasi-intermittent failure rate increases and the mean time to failure descreases.

Oneill, E. J.↗
NASA NTRS1985

Preparation and analysis of particulate metal deposits

Small particles and clusters of palladium were grown by deposition from the vapor phase under ultrahigh vacuum conditions. Amorphous and crystalline support films of Al2O3 and ultrathin amorphous carbon films were used as substrate materials. The growth of the metal deposit was monitored in situ by scanning transmission diffraction of energy-filtered 100 kV electrons and high resolution transmission electron microscopy (TEM) analysis was performed in a separate instrument. It was established by in situ TEM, however, that the transfer of specimens in this case did not unduly affect the size and distribution of deposit particles. It was found that the cleanness, stoichiometry, crystallinity and structural perfection of the support surface play an essential role in determining the crystalline perfection and structure of the particles. The smallest palladium clusters reproducibly prepared contained not more than six atoms but size determinations below 1 nm average particle diameter are very problematic with conventional TEM. Palladium particles grown on carbon supports feature an impurity-stabilized mosaic structure.

Poppa, H.↗
NASA NTRS1991

Thermal analysis of the ultraviolet imager camera and electronics

The Ultraviolet Imaging experiment has undergone design changes that necessiate updating the reduced thermal models (RTM's) for both the Camera and Electronics. In addition, there are several mission scenarios that need to be evaluated in terms of thermal response of the instruments. The impact of these design changes and mission scenarios on the thermal performance of the Camera and Electronics assemblies is discussed.

Dirks, Gregory J.↗
NASA NTRS1992

Frequency monitoring a LIDAR transmitter for pulse-by-pulse analysis and control

An electronic technique is described whereby the heterodyne mixing frequency of a pulsed LIDAR transmitter is displayed on a color-coded linear bar graph. The technique is of great utility for manually fine tuning the laser output frequency when the use of conventional frequency counters and spectrum analyzers is impractical in a rapidly firing system.

Esproles, Carlos↗
NASA NTRS1998

An Assessment of Molten Metal Detachment Hazards for Electron Beam Welding in the Space Environment: Analysis and Test Results

Conditions under which molten metal detachments might occur in a space welding environment are analyzed. A weld pool detachment parameter specifying conditions for pool detachment by impact is derived and corroborated by experimental evidence. Impact detachment for the pool is unlikely. Impact detachment for a drop of metal on the end of the weld wire may be possible under extreme conditions. Other potential causes of molten metal detachment considered, vaporization pressure forces and wire flickout from the pool, did not appear to present significant detachment threats.

Nunes, A. C., Jr.↗
NASA NTRS1998

Frequency-Domain Analysis of Diffusion-Cooled Hot-Electron Bolometer Mixers

A new theoretical model is introduced to describe heterodyne mixer conversion efficiency and noise (from thermal fluctuation effects) in diffusion-cooled superconducting hot-electron bolometers. The model takes into account the non-uniform internal electron temperature distribution generated by Wiedemann-Franz heat conduction, and accepts for input an arbitrary (analytical or experimental) superconducting resistance-versus- temperature curve. A non-linear large-signal solution is solved iteratively to calculate the temperature distribution, and a linear frequency-domain small-signal formulation is used to calculate conversion efficiency and noise. In the small-signal solution the device is discretized into segments, and matrix algebra is used to relate the heating modulation in the segments to temperature and resistance modulations. Matrix expressions are derived that allow single-sideband mixer conversion efficiency and coupled noise power to be directly calculated. The model accounts for self-heating and electrothermal feedback from the surrounding bias circuit.

Skalare, A.↗
NASA NTRS2015

Morphological Processing of Ultraviolet Emissions of Electrical Corona Discharge for Analysis and Diagnostic Use

Electron cascades from electrical discharge produce secondary emissions from atmospheric plasma in the ultraviolet band. For a single point of discharge, these emissions exhibit a stereotypical discharge morphology, with latent information about the discharge location. Morphological processing can uncover the location and therefore can have diagnostic utility.

Schubert, Matthew R.↗
NASA NTRS1992

Surface analysis of anodized aluminum clamps from NASA-LDEF satellite

Surface analysis results of selected anodized aluminum clamps containing black (Z306) and white (A276) paints which received nearly six years of Low Earth Orbit (LEO) exposure on the Long Duration Exposure Facility are reported. Surface analytical techniques, including x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and scanning electron microscopy/energy dispersive analysis by x-ray (SEM/EDAX), showed significant differences in the surface composition of these materials depending upon the position on the LDEF. Differences in the surface composition are attributed to varying amounts of atomic oxygen and vacuum ultraviolet radiation (VUV). Silicon containing compounds were the primary contaminant detected on the materials.

Grammer, H. L.↗
DOE OSTI2026

Electron–Ion Covariance Reveals Geometry-Resolved Inner-Shell Spectra in CS 2 Photodissociation

The chemical shifts of inner-shell atomic orbitals are highly sensitive to chemical bonding and molecular structure. In evolving systems, however, the spectra of distinct molecular species and geometries overlap, obscuring the underlying chemical dynamics. Here we demonstrate the use of electron–ion covariance analysis to combine the structural sensitivity of Coulomb explosion imaging with inner-shell spectroscopy, yielding geometry-specific spectra of transient and product species. We apply this approach to the excited state dynamics of CS 2 probed by ionization above the S 2p edge. Electron–ion covariance with time- and momentum-selected S + and S 2+ ions isolates distinct S 2p photoelectron spectra for ground-state CS 2 , bent photoexcited CS 2 , the CS photoproduct, and bare atomic sulfur ─ species whose spectra overlap strongly in the channel-averaged measurement. Clear chemical shifts are observed in the covariance photoelectron spectrum for each of these species, all of which are consistent with high-level calculations. Here, by extracting the atomic S contribution to the photoelectron spectrum in a finely time-resolved manner we can disentangle this contribution to the overall time-resolved photoelectron spectrum as the photodissociation proceeds. These results demonstrate the promise of electron–ion covariance as a general approach to geometry-resolved inner-shell spectroscopy, opening a route to tracking structural evolution through chemical shifts in complex photoexcited molecules.

Ionization↗