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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 991 records · Page 55
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Impact of power flow on Z-pinch loads

Magnetically insulated transmission lines (MITLs) are used to deliver tens of MA to a Z-pinch load. The MITLs suffer current losses due to contaminant plasma located in the anode–cathode gap which is swept toward the load along the power flow. The swept up contaminant plasma can deposit mass and energy onto the load resulting in deformations or the seeding of macroscopic instabilities. This paper discusses 2D fully kinetic simulations of the contaminant plasma evolution which predict the current losses and the flux of mass and energy onto the load. Furthermore, the effects of a dynamic, i.e., imploding, load are shown to increase both the current loss and the mass and energy flux. The MITL used is a conical, radially converging design which is a feature common to MA-scale Z-pinch accelerators.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2024

Plasma–liquid interactions in the presence of organic matter—A perspective

As investigations in the biomedical applications of plasma advance, a demand for describing safe and efficacious delivery of plasma is emerging. It is quite clear that not all plasmas are “equal” for all applications. This Perspective discusses limitations of the existing parameters used to define plasma in context of the need for the “right plasma” at the “right dose” for each “disease system.” The validity of results extrapolated from in vitro studies to preclinical and clinical applications is discussed. We make a case for studying the whole system as a single unit, in situ. Furthermore, we argue that while plasma-generated chemical species are the proposed key effectors in biological systems, the contribution of physical effectors (electric fields, surface charging, dielectric properties of target, changes in gap electric fields, etc.) must not be ignored.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

First principles study of nearly strain-free Ni/WSe 2 and Ni/MoS 2 interfaces

Metal/transition metal dichalcogenide interfaces are the subject of active research, in part because they provide various possibilities for interplay of electronic and magnetic properties with potential device applications. Here, we present results of our first principles calculations of nearly strain-free Ni/WSe 2 and Ni/MoS 2 interfaces in thin-film geometry. It is shown that while both the WSe 2 and MoS 2 layers adjacent to Ni undergo metallic transition, the layers farther from the interface remain semiconducting. In addition, a moderate value of spin-polarization is induced on interfacial WSe 2 and MoS 2 layers. At the same time, the electronic and magnetic properties of Ni are nearly unaffected by the presence of WSe 2 and MoS 2 , except a small reduction of magnetic moment at the interfacial Ni atoms. Furthermore, these results can be used as a reference for experimental efforts on epitaxial metal/transition metal dichalcogenide heterostructures, with potential application in modern magnetic storage devices.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

Origin of surface and subband states at the InAs(111)A surface

The atomic structure of surfaces and interfaces plays a vital role in the electronic quality and properties of quantum devices. The interplay between the surface and confined bulk subband states in terms of their susceptibility has been investigated in relation to crystal defects on an InAs(111)A-(2×2) reconstructed surface, using low-temperature scanning tunneling microscopy and spectroscopy. We measure the two-dimensional quantized subband states arising from the confined potential imposed by downward bending of the conduction band edge. Furthermore, we show evidence of the existence of surface Bloch states within the confined bulk band gap projected on the surface spectrum which have originated from the surface reconstruction. As expected, larger confined bulk band gaps at the surface and conduction band offset are measured to be 0.58 and 0.31 eV, respectively. Here we further show the scattering of these quantum states at different surface defects and demonstrate that surface states are more susceptible to the defect potential when compared with the corresponding subband states. This apparent contrast follows from the length scale at which these defect potentials actively interact on or near the surface. Our observed experimental results are supported by empirical tight-binding simulations for the subband states and first-principles density functional theory simulations for the surface states present on the surface.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2026

Time-domain terahertz emission spectroscopy on van der Waals materials

Time-domain terahertz (THz) emission spectroscopy provides a direct method to probe transient photo-currents by recording the emitted terahertz electric field. Although the basic principles of THz surface emission have been understood for more than 30 years, the constant progress in ultrafast laser science to ever shorter pulses, the development of new materials and enhanced sensitivity promote THz emission spectroscopy as a reliable method to gain insights into charge carrier dynamics with unprecedented precision. It provides a versatile tool to study ultrafast processes, such as plasmon-driven hot carriers, dynamics of Dirac fermions, interfacial charge transfer, coherent phonon emission and quantum beating, to name only a few. However, despite the rapidly growing body of research on van der Waals materials, especially in their low-dimensional limit, THz emission spectroscopy has only been applied to a limited extent in these material systems. In this prospective, we review time-domain THz emission spectroscopy as a complementary approach to probe ultrafast charge carrier dynamics and the material’s nonlinear response. After a description of the experimental method, we report on THz emission spectroscopy of bulk and 2D van der Waals materials with special focus on graphene and transition metal dichalcogenide layers.

2D materials↗
DOE OSTI2022

Utilization of 29Si MAS-NMR to Understand Solid State Diffusion in Energy Storage Materials

The properties of many solid-state materials arise from critical interfaces tied to the structure, morphology, and composition of the materials under study. For many materials, identifying components that may be invisible to diffraction techniques or other bulk sensitive techniques (i.e. inductively coupled plasma (ICP)), may cause important information to be overlooked. These can include grain boundary phases, nanoscale coatings, amorphous layers, or second phases that influence the materials environment. In this short review, the use of 29 Si MAS NMR as a local probe to detect silicon-containing phases in complex energy storage systems is explored with a focus is on silicon-containing materials and silicon electrodes. Examples highlighting the utility of 29 Si MAS NMR include 1) examining copper diffusion into silicon as a method to create 3 dimensional electrodes, 2) using Mg(II) electrolyte additives to create in-situ nanoscale silicide coatings to inhibit low voltage parasitic side reactions and extend calendar life, and 3) studying the lithiation reactions of passivated silicon on different time scales.

Dogan, Fulya↗
DOE OSTI2023

Developing Enzyme Immobilization with Fibrous Membranes: Longevity and Characterization Considerations

Fibrous membranes offer broad opportunities to deploy immobilized enzymes in new reactor and application designs, including multiphase continuous flow-through reactions. Enzyme immobilization is a technology strategy that simplifies the separation of otherwise soluble catalytic proteins from liquid reaction media and imparts stabilization and performance enhancement. Flexible immobilization matrices made from fibers have versatile physical attributes, such as high surface area, light weight, and controllable porosity, which give them membrane-like characteristics, while simultaneously providing good mechanical properties for creating functional filters, sensors, scaffolds, and other interface-active biocatalytic materials. This review examines immobilization strategies for enzymes on fibrous membrane-like polymeric supports involving all three fundamental mechanisms of post-immobilization, incorporation, and coating. Post-immobilization offers an infinite selection of matrix materials, but may encounter loading and durability issues, while incorporation offers longevity but has more limited material options and may present mass transfer obstacles. Coating techniques on fibrous materials at different geometric scales are a growing trend in making membranes that integrate biocatalytic functionality with versatile physical supports. Biocatalytic performance parameters and characterization techniques for immobilized enzymes are described, including several emerging techniques of special relevance for fibrous immobilized enzymes. Diverse application examples from the literature, focusing on fibrous matrices, are summarized, and biocatalyst longevity is emphasized as a critical performance parameter that needs increased attention to advance concepts from lab scale to broader utilization. This consolidation of fabrication, performance measurement, and characterization techniques, with guiding examples highlighted, is intended to inspire future innovations in enzyme immobilization with fibrous membranes and expand their uses in novel reactors and processes.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Processing, Microstructure, and Properties of Bimetallic Steel-Ni Alloy Powder HIP

This work explores technical feasibility in hot isostatic pressing (HIP) manufacturing of an integral bimetallic component using steel and Ni alloy powder for supercritical carbon dioxide (sCO2) turbomachinery. Lab-scale bimetallic HIP specimens using HAYNES® 282® and SS316L or SS415 powder are investigated in powder configuration, heat treatment, microstructure, and tensile properties up to 400 °C. Interdiffusion profiles at dissimilar alloy interfaces caused by HIP cycle is predicted by DICTRA simulations and validated by electron probe microanalysis (EPMA). The interdiffusion distance of most elements is around 100 μm, while C and N have a higher interdiffusion distance. Dense distribution of Ti-rich carbonitrides and alumina particles are found to decorate prior particle boundaries near joining interface on the 282 side, affecting tensile strength across interface as well as tensile failure location. A higher amount of excessive carbonitride formation near interface is observed in SS316L/282 than in SS415/282, which is consistent with the predicted greater degree of interdiffusion effect in SS316L/282. Typical HAYNES® 282® heat treatment condition is applicable to 282/SS316L and 282/SS415 combinations, resulting in a higher strength than cast CF8M and CA6NM. A pilot-scale bimetallic SS415/282 pipe is then demonstrated to show the promise of scaleup.

36 MATERIALS SCIENCE↗
NASA NTRS1972

Diffusion bonding and its application to manufacturing

In its simplest form diffusion bonding is accomplished by placing clean metal surfaces together under a sufficient load and heating. The natural interatomic attractive force between atoms transforms the interface into a natural grain boundary. Therefore, in principle, the properties of the bond area are identical to those of the parent metal. Other advantages of diffusion bonding over conventional methods of bonding include freedom from residual stresses, excessive deformation, foreign metals, or changed crystal structures. Stainless steels, nickel-base superalloys, and aluminum alloys have all been successfully joined. Complex hardware, including integrated flueric devices, jet engine servovalves, and porous woven structures have been fabricated. The processing involved is discussed, along with such theoretical considerations as the role of metal surfaces, the formation of metal contact junctions, and the mechanisms of material transport in diffusion bonding.

Spurgeon, W. M.↗
NASA NTRS1974

Mechanics of load transfer at the interface

The mechanism of load transfer from matrix to fiber though the interface and, as a consequence, the effects of the interface on composite structural integrity are discussed. Specifically, the present work deals with the role of interfacial bonding in composite strength, the dependence of fracture surface on interface bond strength, and methods of measuring and predicting the stress at the interface, the microresidual stress, and load condition effects on the interface bond. The possibility of designing composites with specified bond properties is examined. Many of these effects are illustrated graphically to indicate general trends and to illustrate significant points. The discussion is based on theoretical considerations and is supplemented with pertinent experimental data.

Chamis, C. C.↗
NASA NTRS1980

International solar polar mission

The key configurations and characteristics of the two International Solar Polar Mission (ISPM) spacecraft are described. The primary mission objectives of the ISPM are to investigate, as a function of solar latitude, the properties of the solar corona, the solar wind, the sun/wind interface, the heliospheric magnetic field, solar and nonsolar cosmic rays, and the interstellar/interplanetary neutral gas and dust. In addition, instrumentation is included to detect the gamma ray bursts; it is hoped to pinpoint the sources of these bursts by using triangulation from each spacecraft and the Earth.

Miller, R. B.↗
NASA NTRS1980

KU-Band rendezvous radar performance computer simulation model

The preparation of a real time computer simulation model of the KU band rendezvous radar to be integrated into the shuttle mission simulator (SMS), the shuttle engineering simulator (SES), and the shuttle avionics integration laboratory (SAIL) simulator is described. To meet crew training requirements a radar tracking performance model, and a target modeling method were developed. The parent simulation/radar simulation interface requirements, and the method selected to model target scattering properties, including an application of this method to the SPAS spacecraft are described. The radar search and acquisition mode performance model and the radar track mode signal processor model are examined and analyzed. The angle, angle rate, range, and range rate tracking loops are also discussed.

Griffin, J. W.↗
NASA NTRS1985

Two-dimensional modelling of compressive failure in delaminated laminates

An analytical model is developed to assess the compressive strength criticality of near-surface interlaminar defects in laminated composites. The delaminated region is elliptic in shape, separating a thick isotropic plate from a thin orthotropic layer whose material axes coincide with the ellipse axes. The growth conditions and growth behavior of this defect are studied by breaking the overall problem into an elastic stability problem and a fracture problem. Post-buckling solution for the elliptic section is obtained using the Rayleigh-Ritz method while an energy balance criterion based on a self-similar disbond growth governs the fracture. The parameters controlling the growth or arrest of the delamination damage are identified as the fracture energy, disbond depth and elastic properties of the materials from both sides of the delaminating interface. By varying the degree of material anisotropy relative to the loading axis a range in growth behavior was found including stable or unstable crack growth parallel to or normal to the loading axis.

Chai, H.↗
NASA NTRS1992

Development and application of a 3-D geometry/mass model for LDEF satellite ionizing radiation assessments

A computer model of the three dimensional geometry and material distributions for the LDEF spacecraft, experiment trays, and, for selected trays, the components of experiments within a tray was developed for use in ionizing radiation assessments. The model is being applied to provide 3-D shielding distributions around radiation dosimeters to aid in data interpretation, particularly in assessing the directional properties of the radiation exposure. Also, the model has been interfaced with radiation transport codes for 3-D dosimetry response predictions and for calculations related to determining the accuracy of trapped proton and cosmic ray environment models. The methodology is described used in developing the 3-D LDEF model and the level of detail incorporated. Currently, the trays modeled in detail are F2, F8, and H12 and H3. Applications of the model which are discussed include the 3-D shielding distributions around various dosimeters, the influence of shielding on dosimetry responses, and comparisons of dose predictions based on the present 3-D model vs those from 1-D geometry model approximations used in initial estimates.

Colborn, B. L.↗
NASA NTRS2001

Java Application Shell: A Framework for Piecing Together Java Applications

This session describes the architecture of Java Application Shell (JAS), a Swing-based framework for developing interactive Java applications. Java Application Shell is being developed by Commerce One, Inc. for NASA Goddard Space Flight Center Code 588. The purpose of JAS is to provide a framework for the development of Java applications, providing features that enable the development process to be more efficient, consistent and flexible. Fundamentally, JAS is based upon an architecture where an application is considered a collection of 'plugins'. In turn, a plug-in is a collection of Swing actions defined using XML and packaged in a jar file. Plug-ins may be local to the host platform or remotely-accessible through HTTP. Local and remote plugins are automatically discovered by JAS upon application startup; plugins may also be loaded dynamically without having to re-start the application. Using Extensible Markup Language (XML) to define actions, as opposed to hardcoding them in application logic, allows easier customization of application-specific operations by separating application logic from presentation. Through XML, a developer defines an action that may appear on any number of menus, toolbars, and buttons. Actions maintain and propagate enable/disable states and specify icons, tool-tips, titles, etc. Furthermore, JAS allows actions to be implemented using various scripting languages through the use of IBM's Bean Scripting Framework. Scripted action implementation is seamless to the end-user. In addition to action implementation, scripts may be used for application and unit-level testing. In the case of application-level testing, JAS has hooks to assist a script in simulating end-user input. JAS also provides property and user preference management, JavaHelp, Undo/Redo, Multi-Document Interface, Single-Document Interface, printing, and logging. Finally, Jini technology has also been included into the framework by means of a Jini services browser and the ability to associate services with actions. Several Java technologies have been incorporated into JAS, including Swing, Internal Frames, Java Beans, XML, JavaScript, JavaHelp, and Jini. Additional information is contained in the original extended abstract.

Miller, Philip↗
NASA NTRS1995

CARES/LIFE Software Commercialization

The NASA Lewis Research Center has entered into a letter agreement with BIOSYM Technologies Inc. (now merged with Molecular Simulations Inc. (MSI)). Under this agreement, NASA will provide a developmental copy of the CARES/LIFE computer program to BIOSYM for evaluation. This computer code predicts the time-dependent reliability of a thermomechanically loaded component. BIOSYM will become familiar with CARES/LIFE, provide results of computations useful in validating the code, evaluate it for potential commercialization, and submit suggestions for improvements or extensions to the code or its documentation. If BIOSYM/Molecular Simulations reaches a favorable evaluation of CARES/LIFE, NASA will enter into negotiations for a cooperative agreement with BIOSYM/Molecular Simulations to further develop the code--adding features such as a user-friendly interface and other improvements. This agreement would give BIOSYM intellectual property rights in the modified codes, which they could protect and then commercialize. NASA would provide BIOSYM with the NASA-developed source codes and would agree to cooperate with BIOSYM in further developing the code. In return, NASA would receive certain use rights in the modified CARES/LIFE program. Presently BIOSYM Technologies Inc. has been involved with integration issues concerning its merger with Molecular Simulations Inc., since both companies used to compete in the computational chemistry market, and to some degree, in the materials market. Consequently, evaluation of the CARES/LIFE software is on hold for a month or two while the merger is finalized. Their interest in CARES continues, however, and they expect to get back to the evaluation by early November 1995.

Source record↗
NASA NTRS2004

Experimentation Toward the Analysis of Gear Noise Sources Controlled by Sliding Friction and Surface Roughness

In helicopters and other rotorcraft, the gearbox is a major source of noise and vibration (N&V). The two N&V excitation mechanisms are the relative displacements between mating gears (transmission errors) and the friction associated with sliding between gear teeth. Historically, transmission errors have been minimized via improved manufacturing accuracies and tooth modifications. Yet, at high torque loads, noise levels are still relatively high though transmission errors might be somewhat minimal. This suggests that sliding friction is indeed a dominant noise source for high power density rotorcraft gearboxes. In reality, friction source mechanism is associated with surface roughness, lubrication regime properties, time-varying friction forces/torques and gear-mesh interface dynamics. Currently, the nature of these mechanisms is not well understood, while there is a definite need for analytical tools that incorporate sliding resistance and surface roughness, and predict their effects on the vibro- acoustic behavior of gears. Toward this end, an experiment was conducted to collect sound and vibration data on the NASA Glenn Gear-Noise Rig. Three iterations of the experiment were accomplished: Iteration 1 tested a baseline set of gears to establish a benchmark. Iteration 2 used a gear-set with low surface asperities to reduce the sliding friction excitation. Iteration 3 incorporated low viscosity oil with the baseline set of gears to examine the effect of lubrication. The results from this experiment will contribute to a two year project in collaboration with the Ohio State University to develop the necessary mathematical and computer models for analyzing geared systems and explain key physical phenomena seen in experiments. Given the importance of sliding friction in the gear dynamic and vibro-acoustic behavior of rotorcraft gearboxes, there is considerable potential for research & developmental activities. Better models and understanding will lead to quiet and reliable gear designs, as well as the selection of optimal manufacturing processes.

Asnani, Vivake M.↗
NASA NTRS1990

Ulysses Launch

Ulysses is a joint mission between the United States National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA) to explore the heliosphere over the full range of solar latitudes, especially in the polar regions. The goal of the Ulysses mission is to provide an accurate assessment of our total solar environment. This collaborative ESA/NASA mission will, for the first time, explore the heliosphere -- the region of space that is dominated by the Sun-- within a few astronomical units of the Sun over the full range of heliographic latitudes. The path followed by the spacecraft, using a Jupiter gravity-assist to achieve a trajectory extending to high solar latitudes, will enable the highly sophisticated scientific instruments on board to make measurements in the uncharted third dimension of the heliosphere. The Ulysses spacecraft will carry nine scientific instruments to measure the properties of the solar corona, the solar wind, the Sun/wind interface, the heliospheric magnetic field, solar radio bursts, plasma waves, solar X-rays, solar and galactic cosmic rays, and the interplanetary/interstellar neutral gas and dust. Scientists will take advantage of the enormous distance between the spacecraft and the Earth to perform astrophysical measurements and to search for gravitational waves. In conjunction with instrumentation on Earth-orbiting spacecraft, Ulysses will help to precisely locate the mysterious sources of cosmic gamma bursts. The results obtained will help to solve outstanding problems in solar and heliospheric physics, while undoubtedly revealing new and unanticipated phenomena.

Source record↗