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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

WE-H-BRC-01: Failure Mode and Effects Analysis of Skin Electronic Brachytherapy Using Esteya Unit

Purpose: A failure mode and effect analysis (FMEA) of skin lesions treatment process using Esteya™ device (Elekta Brachyterapy, Veenendaal, The Netherlands) was performed, with the aim of increasing the quality of the treatment and reducing the likelihood of unwanted events. Methods: A multidisciplinary team with experience in the treatment process met to establish the process map, which outlines the flow of various stages for such patients undergoing skin treatment. Potential failure modes (FM) were identified and the value of severity (S), frequency of occurrence (O), and lack of detectability (D) of the proposed FM were scored individually, each on a scale of 1 to 10 following TG-100 guidelines of the AAPM. These failure modes were ranked according to our risk priority number (RPN) and S scores. The efficiency of existing quality management tools was analyzed through a reassessment of the O and D made by consensus. Results: 149 FM were identified, 43 of which had RPN ≥ 100 and 30 had S ≥ 7. After introduction of the tools of quality management, only 3 FM had RPN ≥ 100 and 22 FM had RPN ≥ 50. These 22 FM were thoroughly analyzed and new tools for quality management were proposed. The most common cause of highest RPN FM was associated with the heavy patient workload and the continuous and accurate applicator-patient skin contact during the treatment. To overcome this second item, a regular quality control and setup review by a second individual before each treatment session was proposed. Conclusion: FMEA revealed some of the FM potentials that were not predicted during the initial implementation of the quality management tools. This exercise was useful in identifying the need of periodic update of the FMEA process as new potential failures can be identified.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Analysis of Multilayer Devices for Superconducting Electronics by High-Resolution Scanning Transmission Electron Microscopy and Energy Dispersive Spectroscopy

We used a focused ion beam to obtain cross-sectional specimens from both magnetic multilayer and Nb/Al-AlOx/Nb Josephson junction devices for characterization by scanning transmission electron microscopy (STEM) and energy dispersive X-ray spectroscopy (EDX). An automated multivariate statistical analysis of the EDX spectral images produced chemically unique component images of individual layers within the multilayer structures. STEM imaging elucidated distinct variations in film morphology, interface quality, and/or etch artifacts that could be correlated to magnetic and/or electrical properties measured on the same devices.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2011

Electron backscatter diffraction analysis of a CZT growth tip from a vertical gradient freeze furnace

Electron backscatter diffraction (EBSD) was used to characterize the growth-tip region of a 4.2-cm diameter CdZnTe (CZT) boule grown using low-pressure Bridgman method in a vertical gradient freeze furnace. The boule was sectioned and polished and a section taken along the boule longitudinal centerline with an approximate surface area of 1-cm 2 was used for optical and scanning electron microscopy. A collage was assembled using EBSD/SEM images to show morphological features, e.g., twin structure, grain structure, and overall crystal growth direction. Severely twinned regions originating from the tip and side walls were observed. The overall growth orientation was close to (1 1 0) and (1 1 2) directions. In some regions, the (0 0 1) poles of the CZT matrix aligned with the growth direction, while twins aligned such that (1 1 1) and (1 1 2) poles aligned with the growth direction. Finally, in some other areas, (1 1 2) or (0 1 1) poles of the CZT matrix aligned with the growth direction. New relationships between the CZT matrix and large Te polycrystalline particles were revealed: {1 1 2 - } CZT ΙΙ{1 1 - 0 0} Te and {0 0 1} CZT II{0 1 - 1 - 1} Te .

58 GEOSCIENCES↗
DOE OSTI2024

Tutorial on In Situ and Operando (Scanning) Transmission Electron Microscopy for Analysis of Nanoscale Structure–Property Relationships

In situ and operando (scanning) transmission electron microscopy [(S)TEM] is a powerful characterization technique that uses imaging, diffraction, and spectroscopy to gain nano-to-atomic scale insights into the structure–property relationships in materials. This technique is both customizable and complex because many factors impact the ability to collect structural, compositional, and bonding information from a sample during environmental exposure or under application of an external stimulus. In the past two decades, in situ and operando (S)TEM methods have diversified and grown to encompass additional capabilities, higher degrees of precision, dynamic tracking abilities, enhanced reproducibility, and improved analytical tools. Much of this growth has been shared through the community and within commercialized products that enable rapid adoption and training in this approach. This tutorial aims to serve as a guide for students, collaborators, and nonspecialists to learn the important factors that impact the success of in situ and operando (S)TEM experiments and assess the value of the results obtained. As this is not a step-by-step guide, readers are encouraged to seek out the many comprehensive resources available for gaining a deeper understanding of in situ and operando (S)TEM methods, property measurements, data acquisition, reproducibility, and data analytics.

(S)TEM↗
DOE OSTI2021

Use of Transmission Electron Microscopy for Analysis of Aerosol Particles and Strategies for Imaging Fragile Particles

For over 25 years, transmission electron microscopy (TEM) has provided a method for the study of aerosol particles with sizes from below the optical diffraction limit to several microns, resolving the particles as well as smaller features. The wide use of this technique to study aerosol particles has contributed important insights about environmental aerosol particle samples and model atmospheric systems. TEM produces an image that is a 2D projection of aerosol particles that have been impacted onto grids and, through associated techniques and spectroscopies, can contribute additional information such as the determination of elemental composition, crystal structure, and 3D particle structures. Soot, mineral dust, and organic/inorganic particles have all been analyzed using TEM and spectroscopic techniques. TEM, however, has limitations that are important to understand when interpreting data including the ability of the electron beam to damage and thereby change the structure and shape of particles, especially in the case of particles composed of organic compounds and salts. In this paper, we concentrate on the breadth of studies that have used TEM as the primary analysis technique. Another focus is on common issues with TEM and cryogenic-TEM. Insights for new users on best practices for fragile particles, that is, particles that are easily susceptible to damage from the electron beam, with this technique are discussed. Tips for readers on interpreting and evaluating the quality and accuracy of TEM data in the literature are also provided and explained.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1973

Use of the SRI electronic satellite image analysis console for mapping southern Arizona plant communities from ERTS-1 imagery

Cloud-free imagery covering the Tucson, Ariz., region for the period from August 22 to November 2, 1972, was used to determine the utility of ERTS-1 data for discriminating boundaries between plant communities. The following studies were made from imagery analyzed by use of an Electronic Satellite Image Analysis Console: (1) console-generated color composites from MSS-5 and MSS-6 bands were recorded photographically from the console color monitor. The color photographs were then used to compare with short-term changes in vegetative cover observed on the ground; (2) using the console, microdensitometric traces were made along selected traverses to quantify changes in scene irradiance across the image field; (3) quantitative plant coverage data, collected at ground-truth stations along the traverses, were compared with the densitometric values.

Turner, R. M.↗
DOE OSTI2012

Model for Electron-Beam-Induced Current Analysis of mc-Si Addressing Defect Contrast Behavior in Heavily Contaminated PV Material: Preprint

Much work has been done to correlate electron-beam-induced current (EBIC) contrast behavior of extended defects with the character and degree of impurity decoration. However, existing models fail to account for recently observed contrast behavior of defects in heavily contaminated mc-Si PV cells. We have observed large increases in defect contrast with decreasing temperature for all electricallyactive defects, regardless of their initial contrast signatures at ambient temperature. This negates the usefulness of the existing models in identifying defect character and levels of impurity decoration based on the temperature dependence of the contrast behavior. By considering the interactions of transition metal impurities with the silicon lattice and extended defects, we attempt to providean explanation for these observations. Our findings will enhance the ability of the PV community to understand and mitigate the effects of these types of defects as the adoption of increasingly lower purity feedstocks for mc-Si PV production continues.

14 SOLAR ENERGY↗
DOE OSTI2019

Structure retrieval from four-dimensional scanning transmission electron microscopy: Statistical analysis of potential pitfalls in high-dimensional data

Four-dimensional (4D) scanning transmission electron microscopy is one of the most rapidly growing modes of electron microscopy imaging. The advent of fast pixelated cameras and the associated data infrastructure have greatly accelerated this process. Yet conversion of the 4D datasets into physically meaningful structure images in real space remains an open issue. In this work, we demonstrate that it is possible to systematically create filters that will affect the apparent resolution or even qualitative features of the real-space structure image, reconstructing artificially generated patterns. As initial efforts, we explore statistical model selection algorithms, aiming for robustness and reliability of estimated filters. This statistical model selection analysis demonstrates the need for regularization and cross validation of inversion methods to robustly recover structure from high-dimensional diffraction datasets.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Langmuir probe measurements in a time-fluctuating-highly ionized non-equilibrium cutting arc: Analysis of the electron retarding part of the time-averaged current-voltage characteristic of the probe

This work describes the application of Langmuir probe diagnostics to the measurement of the electron temperature in a time-fluctuating-highly ionized, non-equilibrium cutting arc. The electron retarding part of the time-averaged current-voltage characteristic of the probe was analysed, assuming that the standard exponential expression describing the electron current to the probe in collision-free plasmas can be applied under the investigated conditions. A procedure is described which allows the determination of the errors introduced in time-averaged probe data due to small-amplitude plasma fluctuations. It was found that the experimental points can be gathered into two well defined groups allowing defining two quite different averaged electron temperature values. In the low-current region the averaged characteristic was not significantly disturbed by the fluctuations and can reliably be used to obtain the actual value of the averaged electron temperature. In particular, an averaged electron temperature of 0.98 ± 0.07 eV (= 11400 ± 800 K) was found for the central core of the arc (30 A) at 3.5 mm downstream from the nozzle exit. This average included not only a time-average over the time fluctuations but also a spatial-average along the probe collecting length. The fitting of the high-current region of the characteristic using such electron temperature value together with the corrections given by the fluctuation analysis showed a relevant departure of local thermal equilibrium in the arc core.

36 MATERIALS SCIENCE↗
NASA NTRS2017

Gaining the most utility from our geospace observational system: Network analysis of total electron content as a means to understand space weather to the point of prediction

We present the first network analysis of interplanetary magnetic field (IMF) clock angle dependent, high-latitude, hemispheric-specific total electron content (TEC) data. We examine network parameters to describe spatio-temporal correlations in the TEC data for January 2016. We find that significant network structure exists distinguishing the dayside and nightside ionosphere, and specific features in the high-latitudes (cusp/ionospheric footpoints of magnetospheric boundary layers, polar cap, and auroral zone), and that these features vary with IMF clock angle. In this brief summary paper, we provide proof of concept results and identify important areas of future research, providing a basis for the discussion of network analysis and machine learning approaches for space weather applications.

Malik, Nishant↗
DOE OSTI2015

Wavefunction stability analysis without analytical electronic Hessians: application to orbital-optimised second-order Møller–Plesset theory and VV10-containing density functionals

Wavefunction stability analysis is commonly applied to converged self-consistent field (SCF) solutions to verify whether the electronic energy is a local minimum with respect to second-order variations in the orbitals. By iterative diagonalisation, the procedure calculates the lowest eigenvalue of the stability matrix or electronic Hessian. However, analytical expressions for the electronic Hessian are unavailable for most advanced post-Hartree-Fock (HF) wave function methods and even some Kohn-Sham (KS) density functionals. To address such cases, here we formulate the Hessian-vector product within the iterative diagonalisation procedure as a finite difference of the electronic gradient with respect to orbital perturbations in the direction of the vector. As a model application, following the lowest eigenvalue of the orbital-optimised second-order Møller-Plesset perturbation theory (OOMP2) Hessian during H 2 dissociation reveals the surprising stability of the spin-restricted solution at all separations, with a second independent unrestricted solution. We show that a single stable solution can be recovered by using the regularised OOMP2 method (δ-OOMP2), which contains a level shift. Internal and external stability analyses are also performed for SCF solutions of a recently developed range-separated hybrid density functional, ωB97X-V, for which the analytical Hessian is not yet available due to the complexity of its long-range non-local VV10 correlation functional.

Brueckner orbitals↗
DOE OSTI2019

Energetic Electron Precipitation: Multievent Analysis of Its Spatial Extent During EMIC Wave Activity

Electromagnetic ion cyclotron (EMIC) waves can drive precipitation of tens of keV protons and relativistic electrons, and are a potential candidate for causing radiation belt flux dropouts. In this study, we quantitatively analyze three cases of EMIC-driven precipitation, which occurred near the dusk sector observed by multiple Low-Earth-Orbiting (LEO) Polar Operational Environmental Satellites/Meteorological Operational satellite programme (POES/MetOp) satellites. During EMIC wave activity, the proton precipitation occurred from few tens of keV up to hundreds of keV, while the electron precipitation was mainly at relativistic energies. We compare observations of electron precipitation with calculations using quasi-linear theory. For all cases, we consider the effects of other magnetospheric waves observed simultaneously with EMIC waves, namely, plasmaspheric hiss and magnetosonic waves, and find that the electron precipitation at MeV energies was predominantly caused by EMIC-driven pitch angle scattering. Interestingly, each precipitation event observed by a LEO satellite extended over a limited L shell region (ΔL ~ 0.3 on average), suggesting that the pitch angle scattering caused by EMIC waves occurs only when favorable conditions are met, likely in a localized region. Furthermore, we take advantage of the LEO constellation to explore the occurrence of precipitation at different L shells and magnetic local time sectors, simultaneously with EMIC wave observations near the equator (detected by Van Allen Probes) or at the ground (measured by magnetometers). Our analysis shows that although EMIC waves drove precipitation only in a narrow ΔL, electron precipitation was triggered at various locations as identified by POES/MetOp over a rather broad region (up to ~4.4 hr MLT and ~1.4 L shells) with similar patterns between satellites.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

Analysis of Organic Electron Materials using Neutron Scattering (Final Report)

Neutron scattering is a powerful suite of measurement techniques that enable unique analysis of structure and dynamics of a wide variety of materials. Specifically, neutrons interact strongly with protons, which enables excellent contrast in light element organic materials that cannot be obtained with any other measurements. This series of three proposals focused on using inelastic neutron scattering (INS) to study the vibrations (dynamics) of the organic molecules involved in organic electronic devices. Our main goals were to demonstrate that INS is capable of elucidating new, useful, and unique knowledge about organic electronic samples that could be used to improve the function of devices or to solve outstanding problems that could not be solved using other measurement techniques. Since all of the goal involved using INS or other neutron techniques to do something “new” a large part of the effort was focused on complex data interpretation and development of modeling workflows that could be used by other members of the organic electronics community to study their materials. To facilitate the goal of making INS measurements more accessible to a broader community and for a wider range of materials, we optimized and engineered the computational workflows to be well documented, publicly available, and user friendly. The individual titles of the three sequential DOE-BES awards are: (1) Engineering doping profiles in organic semiconducting materials, (2) Measurement and modeling of molecular dopant structure and dynamics, and (3) Quantification of Dynamic Disorder in Electronic and Excitonic Organic Materials. For readability, this report is organized to highlight the progress of the research thematically. Many of the ideas started in one grant period and then spilled over into later awards and collaborative research.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Liquidus projection of the Ag-Ba-Ge system and melting points of clathrate type-I compounds

The liquidus and solidus projection has been constructed for the Ag-Ba-Ge system up to 33.3 at% Ba, using electron micro probe analysis (EPMA), X-ray powder diffraction (XRD) and differential thermal analysis (DSC/DTA). Eight different primary crystallization regions were found: (Ge), Ba{sub 8}Ag{sub x}Ge{sub 46-x-y}{open_square}{sub y} ({kappa}{sub I}) ({open_square} is a vacancy), Ba{sub 6}Ag{sub x}Ge{sub 25-x} ({kappa}{sub Ix}), BaGe{sub 2}, Ba(Ag{sub 1-x}Ge{sub x}){sub 2} ({tau}{sub 1}), BaAg{sub 2-x}Ge{sub 2+x} ({tau}{sub 2}) BaAg{sub 5} and (Ag). The ternary invariant reactions have been determined for the region investigated and are the basis for a Schulz-Scheil diagram. The second part of this work provides a comprehensive compilation of melting points of ternary A{sub 8}T{sub x}M{sub 46-x} and quaternary (A=Sr, Ba, Eu; T=Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga; M=Si, Ge, Sn) clathrate type-I compounds and decomposition temperatures of inverse clathrate type-I Ge{sub 38}{l_brace}P,As,Sb{r_brace}{sub 8}{l_brace}Cl,Br,I{r_brace}{sub 8}, Si{sub 46-x}P{sub x}Te{sub y} and tin based compounds. - Graphical Abstract: Partial liquidus projection of the Ag-Ba-Ge system. Highlights: Black-Right-Pointing-Pointer The liquidus and solidus projection has been constructed for the Ag-Ba-Ge system up to 33.33 at% Ba. Black-Right-Pointing-Pointer Eight different primary crystallization fields have been found. Black-Right-Pointing-Pointer All the ternary compounds form congruently from the melt. Black-Right-Pointing-Pointer The ternary invariant reactions have been determined and are the basis for a Schulz-Scheil diagram.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Three-dimensional analysis of microbunched electron cooling

Microbunched electron cooling (MBEC, Ratner, ), a special category of coherent electron cooling, has been under consideration as a candidate method for the strong hadron cooling component of the Electron Ion Collider (EIC) at BNL. Most of the theoretical treatments of this scheme so far have been based on simplified models for the key space charge effect in which electrons and/or hadrons are approximated by charged disks. Although such disk-based models provide a flexible tool that captures a good part of the underlying physics, they lack the fidelity and robustness of a rigorous analysis that explicitly treats the hadron and cooler electron beams as collections of point charges. In this paper, we present such a rigorous, three-dimensional (3D) model, both from a theory-based and a simulation perspective. Specifically, we calculate the generalized wakefield (or Green’s function) of the cooling system—a crucial quantity that determines the overall performance—paying special attention to the dependence of the wake on the hadron transverse positions. Additionally, our treatment takes into account previously neglected 3D effects that can cause damping of the plasma oscillations in the amplification section of the cooler, such as focusing and the angular spread of the electron beam. Published by the American Physical Society 2025

43 PARTICLE ACCELERATORS↗