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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 1,567 records · Page 87
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Coherent Transfer of Lattice Entropy via Extreme Nonlinear Phononics in Metal Halide Perovskites

Entropy transfer in metal halide perovskites, characterized by significant lattice anharmonicity and low stiffness, underlies the remarkable properties observed in their optoelectronic applications, ranging from solar cells to lasers. The conventional view of this transfer involves stochastic processes occurring within a thermal bath of phonons, where the lattice arrangement and energy flow from higher- to lower-frequency modes. Here, we unveil a comprehensive chronological sequence detailing a conceptually distinct coherent transfer of entropy in a prototypical perovskite CH 3 NH 3 Pbl 3 . The terahertz periodic modulation imposes vibrational coherence into electronic states, leading to the emergence of mixed (vibronic) quantum beat between approximately 3 and 0.3 THz. We highlight a well-structured bidirectional time-frequency transfer of these diverse phonon modes, each developing at different times and transitioning from high to low frequencies from 3 to 0.3 THz, before reversing direction and ascending to around 0.8 THz. First-principles molecular dynamics simulations disentangle a complex web of coherent-phononic coupling pathways and identify the salient roles of the initial modes in shaping entropy evolution at later stages. Capitalizing on coherent entropy transfer and dynamic anharmonicity presents a compelling opportunity to exceed the fundamental thermodynamic (Shockley-Queisser) limit of photoconversion efficiency and to pioneer novel optoelectronic functionalities. Published by the American Physical Society 2024

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2011

Fundamental Drop Dynamics and Mass Transfer Experiments to Support Solvent Extraction Modeling Efforts

In support of the Nuclear Energy Advanced Modeling Simulation Safeguards and Separations (NEAMS SafeSep) program, the Idaho National Laboratory (INL) worked in collaboration with Los Alamos National Laboratory (LANL) to further a modeling effort designed to predict mass transfer behavior for selected metal species between individual dispersed drops and a continuous phase in a two phase liquid-liquid extraction (LLE) system. The purpose of the model is to understand the fundamental processes of mass transfer that occur at the drop interface. This fundamental understanding can be extended to support modeling of larger LLE equipment such as mixer settlers, pulse columns, and centrifugal contactors. The work performed at the INL involved gathering the necessary experimental data to support the modeling effort. A custom experimental apparatus was designed and built for performing drop contact experiments to measure mass transfer coefficients as a function of contact time. A high speed digital camera was used in conjunction with the apparatus to measure size, shape, and velocity of the drops. In addition to drop data, the physical properties of the experimental fluids were measured to be used as input data for the model. Physical properties measurements included density, viscosity, surface tension and interfacial tension. Additionally, self diffusion coefficients for the selected metal species in each experimental solution were measured, and the distribution coefficient for the metal partitioning between phases was determined. At the completion of this work, the INL has determined the mass transfer coefficient and a velocity profile for drops rising by buoyancy through a continuous medium under a specific set of experimental conditions. Additionally, a complete set of experimentally determined fluid properties has been obtained. All data will be provided to LANL to support the modeling effort.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
NASA NTRS1995

Helpful hints to painless payload processing

The helpful hints herein describe, from a system perspective, the functional flow of hardware and software. The flow will begin at the experiment development stage and continue through build-up, test, verification, delivery, launch and deintegration of the experiment. An effort will be made to identify those interfaces and transfer functions of processing that can be improved upon in the new world of 'Faster, Better, and Cheaper.' The documentation necessary to ensure configuration and processing requirements satisfaction will also be discussed. Hints and suggestions for improvements to enhance each phase of the flow will be derived from extensive experience and documented lessons learned. Charts will be utilized to define the functional flow and a list of 'lessons learned' will be addressed to show applicability. In conclusion, specific improvements for several areas of hardware processing, procedure development and quality assurance, that are generic to all Small Payloads, will be identified.

Terhune, Terry↗
DOE OSTI2022

Thermal Instability in the Manufacturing of Wind Turbine Blade Spar Caps – Phase 2

As the wind turbine industry continues to develop, the technology surrounding the design, development, and manufacturing of blades requires advancement as well. Wind turbine blades continue to increase in size, increasing the cost and time associated with manufacturing. Simulation driven manufacturing cycle design is required for the industry to maintain manufacturing schedules and optimize the manufacturing process. A recent effort to reduce the cycle time of wind blade spar caps encountered a recurring manufacturing defect during the exotherm and curing of the resin system after filling in the vacuum-assisted resin transfer molding (VARTM) process. Thermal waves developed in sections of the spar cap resulting in unacceptable part tolerances, requiring the parts to be thrown out. The first phase of this IACMI project focused on characterizing the fabric and epoxy system used in manufacturing and simulating the manufacturing process to determine the root cause of the thermal waves. The second phase of this project refined and validated the manufacturing simulations. The simulation workflow was then used to analyze multiple cure cycle options to determine if the thermal waves would appear. The estimated filling time from the filling simulation was shown to match well to experiment, and the temperature history from the curing simulation lined up well with experiment. This indicates that these simulations could be used to evaluate future curing cycles to be used with manufacturing. It is recommended that the distortion simulation work be completed for this project, as it would allow for further manufacturing cycle evaluation through the prediction of stresses and strains in the part. This could provide indicators of defects like the thermal waves seen in manufacturing earlier.

17 WIND ENERGY↗
NASA NTRS2006

Polymer based tunneling sensor

A process for fabricating a polymer based circuit by the following steps. A mold of a design is formed through a lithography process. The design is transferred to a polymer substrate through a hot embossing process. A metal layer is then deposited over at least part of said design and at least one electrical lead is connected to said metal layer.

Cui, Tianhong↗
NASA NTRS2016

Design, Development and Hotfire Testing of Monolithic Copper and Bimetallic Additively Manufactured Combustion Chambers

NASA and industry partners are working towards fabrication process development to reduce costs and schedules associated with manufacturing liquid rocket engine components with the goal of reducing overall mission costs. One such technique being evaluated is powder-bed fusion or selective laser melting (SLM) otherwise commonly referred to as additive manufacturing. The NASA Low Cost Upper Stage Propulsion (LCUSP) program was designed to develop processes and material characterization for the GRCop-84 copper-alloy commensurate with powder bed additive manufacturing, evaluate bimetallic deposition and complete testing of a full scale combustion chamber. As part of this development, the process has been transferred to industry partners to enable a long-term supply chain of monolithic copper combustion chambers. As a direct spin off of this program, NASA is working with industry partners to further develop the printing process for the GRCop-84 material in addition to the C-18150 (CuCrZr) material. To advance the process further and allow for optimization with multiple materials, NASA is also investigating the feasibility of bimetallic additively manufactured chambers. A 1.2k sized thrust-chamber was designed and developed to compare the printing process of the GRCop-84 and C-18150 SLM materials. A series of similar MCC liners also completed development with an Inconel 625 jacket bonded to the GRcop-84 liner evaluating direct metal deposition (DMD) laser and arc-based techniques. This paper describes the design, development, manufacturing and testing of these combustion chambers and associated lessons learned throughout the design and development process.

Gradl, Paul↗
DOE OSTI2013

Influence of Gd{sup 3+} on the visible quantum cutting in green-emitting silicate Na{sub 3}Gd{sub 0.9−x}Y{sub x}Si{sub 3}O{sub 9}:0.1Tb{sup 3+} phosphors

Highlights: ► The visible quantum cutting between Tb{sup 3+} in silicate Na{sub 3}Gd{sub 0.9−x}Y{sub x}Si{sub 3}O{sub 9}:0.1Tb{sup 3+} phosphors are firstly investigated. ► Gd{sup 3+} plays an important intermediate role during the QC process and reinforces the cross relaxation efficiency. ► Na{sub 3}Gd{sub 0.9}Tb{sub 0.1}Si{sub 3}O{sub 9} has potential application for 3D-PDPs and Hg-free lamps for the total QE of 151.2%. - Abstract: The visible quantum cutting via cross-relaxation between Tb{sup 3+} ions in Na{sub 3}Gd{sub 0.9−x}Y{sub x}Si{sub 3}O{sub 9}:0.1Tb{sup 3+} phosphors are identified for the first time. It has also been found that with the increase of the ratio of Gd{sup 3+}/Y{sup 3+}, the quantum cutting efficiency increases, which indicates the Gd{sup 3+} plays an important intermediate role in energy transfer to convert vacuum ultraviolet light to visible light and reinforces the cross relaxation efficiency during the quantum cutting process. In addition, the energy transfer process from Gd{sup 3+} to Tb{sup 3+} is also investigated and discussed in terms of luminescence spectra.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Time-resolved chemically-selective spectroscopic investigation of the redox reaction between hematite and aluminium

Thermite reactions –highly energetic redox processes between a metal and an oxide—are used in welding, propulsion, and the fabrication of advanced materials. When reduced to the nanoscale, these reactions exhibit enhanced energetic performance, but their ultrafast dynamics remain poorly understood. Gaining insight into charge transfer during these processes is essential for advancing applications in energy conversion and materials design. Here we show that the reaction between aluminium and hematite, a common iron oxide, can be tracked with femtosecond resolution using extreme ultraviolet (EUV) time-resolved absorption spectroscopy at the Fe M 2,3 and Al L 2,3 edges. By exciting the system with an ultrashort optical pulse and probing element-specific absorption changes, we observe an early spectral shift that reveals the formation of localized charge carriers (polarons). Comparing samples with different supporting substrates highlights ultrafast electron transfer from aluminium to hematite. These results demonstrate an approach to investigating charge flow in energetic materials and provide a basis for studying fast chemical reactions with chemical specificity.

Electron transfer↗
DOE OSTI2012

Liquid Salt Heat Exchanger Technology for VHTR Based Applications

The objective of this research is to evaluate performance of liquid salt fluids for use as a heat carrier for transferring high-temperature process heat from the very high-temperature reactor (VHTR) to chemical process plants. Currently, helium is being considered as the heat transfer fluid; however, the tube size requirements and the power associated with pumping helium may not be economical. Recent work on liquid salts has shown tremendous potential to transport high-temperature heat efficiently at low pressures over long distances. This project has two broad objectives: To investigate the compatibility of Incoloy 617 and coated and uncoated SiC ceramic composite with MgCl 2 -KCl molten salt to determine component lifetimes and aid in the design of heat exchangers and piping; and, To conduct the necessary research on the development of metallic and ceramic heat exchangers, which are needed for both the helium-to-salt side and salt-to-process side, with the goal of making these heat exchangers technologically viable. The research will consist of three separate tasks. The first task deals with material compatibility issues with liquid salt and the development of techniques for on-line measurement of corrosion products, which can be used to measure material loss in heat exchangers. Researchers will examine static corrosion of candidate materials in specific high-temperature heat transfer salt systems and develop an in situ electrochemical probe to measure metallic species concentrations dissolved in the liquid salt. The second task deals with the design of both the intermediate and process side heat exchanger systems. Researchers will optimize heat exchanger design and study issues related to corrosion, fabrication, and thermal stresses using commercial and in-house codes. The third task focuses integral testing of flowing liquid salts in a heat transfer/materials loop to determine potential issues of using the salts and to capture realistic behavior of the salts in a small scale prototype system. This includes investigations of plugging issues, heat transfer, pressure drop, and the corrosion and erosion of materials in the flowing system.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
NASA NTRS1990

Geodetic positioning of the Aerospace Electronics Research Lab (ERL) Osborne Time Transfer Receiver (TTR) using the GPS NAVSTAR Block I satellites

Aerospace has routinely processed the Osborne Time Transfer Receiver (TTR) data for the purpose of monitoring the performance of ground and GPS atomic clocks in near real-time with on-line residual displays and characterizing clock stability with Allan Variance calculations. Recently, Aerospace added the ability to estimate the TTR's location by differentially correcting the TTR's location in the WGS84 reference system. This new feature is exercised on a set of TTR clock phase data and Sub-meter accurate station location estimates of the TTR at the Aerospace Electronic Research Lab (ERL) are obtained.

Liu, Anthony S.↗
DOE OSTI2024

Trapped-ion quantum simulation of electron transfer models with tunable dissipation

Electron transfer is at the heart of many fundamental physical, chemical, and biochemical processes essential for life. The exact simulation of these reactions is often hindered by the large number of degrees of freedom and by the essential role of quantum effects. Here, we experimentally simulate a paradigmatic model of molecular electron transfer using a multispecies trapped-ion crystal, where the donor-acceptor gap, the electronic and vibronic couplings, and the bath relaxation dynamics can all be controlled independently. By manipulating both the ground-state and optical qubits, we observe the real-time dynamics of the spin excitation, measuring the transfer rate in several regimes of adiabaticity and relaxation dynamics. Our results provide a testing ground for increasingly rich models of molecular excitation transfer processes that are relevant for molecular electronics and light-harvesting systems.

Science & Technology - Other Topics↗
NASA NTRS2006

Pulse-Flow Microencapsulation System

The pulse-flow microencapsulation system (PFMS) is an automated system that continuously produces a stream of liquid-filled microcapsules for delivery of therapeutic agents to target tissues. Prior microencapsulation systems have relied on batch processes that involve transfer of batches between different apparatuses for different stages of production followed by sampling for acquisition of quality-control data, including measurements of size. In contrast, the PFMS is a single, microprocessor-controlled system that performs all processing steps, including acquisition of quality-control data. The quality-control data can be used as real-time feedback to ensure the production of large quantities of uniform microcapsules.

Morrison, Dennis R.↗
DOE OSTI2015

Layer-transferred MoS{sub 2}/GaN PN diodes

Electrical and optical characterization of two-dimensional/three-dimensional (2D/3D) p-molybdenum disulfide/n-gallium nitride (p-MoS{sub 2}/n-GaN) heterojunction diodes are reported. Devices were fabricated on high-quality, large-area p-MoS{sub 2} grown by chemical vapor deposition on sapphire substrates. The processed devices were transferred onto GaN/sapphire substrates, and the transferred films were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM). On-axis XRD spectra and surface topology obtained from AFM scans were consistent with previously grown high-quality, continuous MoS{sub 2} films. Current-voltage measurements of these diodes exhibited excellent rectification, and capacitance-voltage measurements were used to extract a conduction band offset of 0.23 eV for the transferred MoS{sub 2}/GaN heterojunction. This conduction band offset was confirmed by internal photoemission measurements. The energy band lineup of the MoS{sub 2}/GaN heterojunction is proposed here. This work demonstrates the potential of 2D/3D heterojunctions for novel device applications.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS1993

Sparking young minds with Moon rocks and meteorites

What could be more exciting than seeing pieces of other worlds? The Apollo program left a legacy of astounding accomplishments and precious samples. Part of the thrill of those lunar missions is brought to schools by the lunar sample educational disks, which contain artifacts of six piloted trips to the Moon. Johnson Space Center (JSC) is preparing 100 new educational disks containing pieces of meteorites collected in Antarctica. These represent chunks of several different asteroids, that were collected in one of the most remote, forbidding environments on Earth. These pieces of the Moon and asteroids represent the products of basic planetary processes (solar nebular processes, initial differentiation, volcanism, and impact), and, in turn, these processes are controlled by basic physical and chemical processes (energy, energy transfer, melting, buoyancy, etc.). Thus, the lunar and meteorite sample disks have enormous educational potential. New educational materials are being developed to accompany the disks. Present materials are not as effective as they could be, especially in relating samples to processes and to other types of data such as spectral studies and photogeology. Furthermore, the materials are out of date. New background materials will be produced for teachers, assembling slide sets with extensive captions, and devising numerous hands-on classroom activities to do while the disks are at a school and before and after they arrive. The classroom activities will be developed by teams of experienced teachers working with lunar and meteorite experts.

Taylor, G. Jeffrey↗
DOE OSTI2018

Energy transfer-enhanced photocatalytic reduction of protons within quantum dot light-harvesting–catalyst assemblies

Significance A feature of natural photosynthetic systems is their ability to operate with the low photon flux of sunlight, where the absorption of light and transport of photochemical potential to the catalytic centers is efficiency-limiting. Natural systems overcome this limitation through a process called energy transfer, where quanta of energy are gathered by many weakly coupled light-absorbing centers that pass the energy among themselves to funnel it to a single catalytic reaction center. Prior to this report, this type of energy migration-based approach to light-powered chemistry has not been employed in artificial photocatalytic systems. This work demonstrates the viability of energy-transfer–based sensitization in colloidal photocatalytic assemblies and provides a framework for its incorporation into scalable solar energy conversion systems.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1972

Data processing 2: Advancements in large scale data processing systems for remote sensing

The development of large scale data processing systems for remote sensing is studied by evaluating: (1) the suitability of several sensor types with regard to producing data required for multispectral machine analysis; (2) various types of data preprocessing necessary to prepare such data for analysis; and (3) transfer of machine processing techniques for earth resources data to user community.

Landgrebe, D. A.↗
DOE OSTI2015

Influence of silver nanoparticles on relaxation processes and efficiency of dipole – dipole energy transfer between dye molecules in polymethylmethacrylate films

The fluorescence and phosphorescence of dyes in thin polymethylmethacrylate (PMMA) films in the presence of ablated silver nanoparticles has been investigated in a wide temperature range by methods of femtosecond and picosecond laser photoexcitation. The fluorescence and phosphorescence times, as well as spectral and kinetic characteristics of rhodamine 6G (R6G) molecules in PMMA films are measured in a temperature range of 80 – 330 K. The temperature quenching activation energy of the fluorescence of R6G molecules in the presence of ablated silver nanoparticles is found. The vibrational relaxation rate of R6G in PMMA films is estimated, the efficiency of the dipole – dipole electron energy transfer between R6G and brilliant green molecules (enhanced by plasmonic interaction with ablated silver nanoparticles) is analysed, and the constants of this energy transfer are determined. (nanophotonics)

77 NANOSCIENCE AND NANOTECHNOLOGY↗