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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 631 records · Page 35
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Electron beam characterization via quantum coherent optical magnetometry

We present a quantum optics-based detection method for determining the position and current of an electron beam. As electrons pass through a dilute vapor of rubidium atoms, their magnetic field perturbs the atomic spin's quantum state and causes polarization rotation of a laser resonant with an optical transition of the atoms. By measuring the polarization rotation angle across the laser beam, we recreate a 2D projection of the magnetic field and use it to determine the e-beam position, size, and total current. We tested this method for an e-beam with currents ranging from 30 to 110 μA. Our approach is insensitive to electron kinetic energy, and we confirmed that experimentally between 10 and 20 keV. In conclusion, this technique offers a unique platform for noninvasive characterization of charged particle beams used in accelerators for particle and nuclear physics research.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2026

Bootstrap embedding for interacting electrons in phonon coherent-state mean field

Here, we develop a Fermi–Bose bootstrap embedding framework for the ground state of interacting electrons coupled to a phonon mean field. The method combines bootstrap embedding for correlated electrons with a self-consistent coherent-state mean-field treatment for phonons. This method models the interacting electron–phonon problem as a system of correlated electrons traveling in a self-consistently specified potential landscape, allowing for efficient treatment of large lattice systems. Convergence of the methods for fragment size and total system size is demonstrated for the one-dimensional Hubbard–Holstein model for up to 350 sites. Finite-size scaling is performed to extrapolate to the infinite system size. Benchmarking against the density matrix renormalization group for a small 8-site system at half- and quarter-filling shows an orders-of-magnitude runtime advantage. The comparison further reveals that the method performs best in regimes dominated by localization, such as the Mott insulating phase and the strong-coupling tiny polaron regime, where the local embedding ansatz is still valid. However, due to the mean-field treatment for phonons, we find limitations of our methods in the weakly coupled delocalized region and at the Peierls transition, where quantum phonon fluctuations and long-range kinetic correlations become substantial.

Islam, Shariful [North Carolina State University, ↗
NASA NTRS1982

Reconnection in two dimensions - Localization of vorticity and current near magnetic X-points

Simulations of reconnection utilizing spectral methods show that the 'reconnection zone' exhibits internal structure in the form of a current filament and a 'quadrupole' of kinetic vorticity. A qualitative model of the dynamical role of these local structures is presented. It is suggested that the effect of small scale structures near the X-point is to increase the rate of reconnection.

Matthaeus, W. H.↗
NASA NTRS1983

Computations and estimates of rate coefficients for hydrocarbon reactions of interest to the atmospheres of outer solar system

The rate coefficients, including Arrhenius parameters, have been computed for a number of chemical reactions involving hydrocarbon species for which experimental data are not available and which are important in planetary atmospheric models. The techniques used to calculate the kinetic parameters include the Troe and semiempirical bond energy-bond order (BEBO) or bond strength-bond length (BSBL) methods.

Laufer, A. H.↗
NASA NTRS1989

Superconducting ceramics in the Bi1.5SrCaCu2O sub x system by melt quenching technique

Bi sub 1.5 SrCaCu sub 2 O sub x has been prepared in the glassy state by rapid quenching of the melt. The kinetics of crystallization of various phases in the glass have been evaluated by a variable heating rate differential scanning calorimetry method. The formation various phases on thermal treatments of the glass has been investigated by powder X-ray diffraction and electrical resistivity measurements. Heating at 450 C formed Bi sub 2 Sr sub 2 CuO sub 6, which disappeared on further heating at 765 C, where Bi sub 2 Sr sub 2 CaCu sub 2 O sub 8 formed. Prolonged heating at 845 C resulted in the formation of a small amount of a phase with T sub c onset of approx. 108 K, believed to be Bi sub 2 Sr sub 2 Ca sub 2 Cu sub 3 O sub 10. This specimen showed zero resistivity at 54 K. The glass ceramic approach could offer several advantages in the fabrication of the high-T sub c superconductors in desired practical shapes such as continuous fibers, wires, tapes, etc.

Bansal, Narottam P.↗
NASA NTRS1925

Elements of the Wing Section Theory and of the Wing Theory

This report contains those results of the theory of wings and of wing sections which are of immediate practical value. They are proved and demonstrated by the use of the simple conceptions of "kinetic energy" and "momentum" only, familiar to every engineer; and not by introducing "isogonal transformations" and "vortices," which latter mathematical methods are not essential to the theory and better are used only in papers intended for mathematicians and special experts.

Munk, Max M↗
NASA NTRS1991

A miniaturized fibrinolytic assay for plasminogen activators

This report describes a micro-clot lysis assay (MCLA) for evaluating fibrinolytic activity of plasminogen activators (PA). Fibrin clots were formed in wells of microtiter plates. Lysis of the clots by PA, indicated by change in turbidity (optical density, OD), was monitored with a microplate reader at five minutes intervals. Log-log plots of PA dilution versus endpoint, the time at which the OD value was halfway between the maximum and minimum value for each well, were linear over a broad range of PA concentrations (2-200 International units/ml). The MCLA is a modification and miniaturization of well established fibrinolytic methods. The significant practical advantages of the MCLA are that it is a simple, relatively sensitive, non-radioactive, quantitative, kinetic, fibrinolytic micro-technique which can be automated.

NASA Discipline Cell Biology↗
NASA NTRS1985

Does nucleation theory apply to the formation of refractory circumstellar grains?

It is pointed out that kinetic factors inherent in cosmic systems will prevent the attainment of an approximate equilibrium precondensation cluster distribution, and that therefore such systems will violate one of the most fundamental assumptions of nucleation theory. More importantly, it is shown that of the 11 refractory metal/metal oxide systems which have been studied experimentally none are consistent with the predictions of either classical nucleation theory or the Lothe-Pound modification. Since no valid method is known by which these deficiencies can be circumvented, it is concluded that nucleation theory cannot be made to work in expanding circumstellar shells. However, a stochastic, kinetic treatment which makes use of experimental and theoretical data for specific refractory systems does appear to be feasible.

Donn, B.↗
DOE OSTI2024

Time-dependent density functional theory with the orthogonal projector augmented wave method

The projector augmented wave (PAW) method of Blöchl linearly maps smooth pseudo wavefunctions to the highly oscillatory all-electron DFT orbitals. Compared to norm-conserving pseudopotentials (NCPP), PAW has the advantage of lower kinetic energy cutoffs and larger grid spacing at the cost of having to solve for non-orthogonal wavefunctions. We earlier developed orthogonal PAW (OPAW) to allow the use of PAW when orthogonal wavefunctions are required. In OPAW, the pseudo wavefunctions are transformed through the efficient application of powers of the PAW overlap operator with essentially no extra cost compared to NCPP methods. Previously, we applied OPAW to DFT. Here, we take the first step to make OPAW viable for post-DFT methods by implementing it in real-time time-dependent (TD) DFT. Using fourth-order Runge–Kutta for the time-propagation, we compare calculations of absorption spectra for various organic and biological molecules and show that very large grid spacings are sufficient, 0.6–0.7 bohr in OPAW-TDDFT rather than the 0.4–0.5 bohr used in traditional NCPP-TDDFT calculations. This reduces the memory and propagation costs by around a factor of 3. Our method would be directly applicable to any post-DFT methods that require time-dependent propagations such as the GW approximation and the Bethe–Salpeter equation.

Chemistry↗
NASA NTRS2015

Analytic Method to Estimate Particle Acceleration in Flux Ropes

The mechanism that accelerates particles to the energies required to produce the observed high-energy emission in solar flares is not well understood. Drake et al. (2006) proposed a kinetic mechanism for accelerating electrons in contracting magnetic islands formed by reconnection. In this model, particles that gyrate around magnetic field lines transit from island to island, increasing their energy by Fermi acceleration in those islands that are contracting. Based on these ideas, we present an analytic model to estimate the energy gain of particles orbiting around field lines inside a flux rope (2.5D magnetic island). We calculate the change in the velocity of the particles as the flux rope evolves in time. The method assumes a simple profile for the magnetic field of the evolving island; it can be applied to any case where flux ropes are formed. In our case, the flux-rope evolution is obtained from our recent high-resolution, compressible 2.5D MHD simulations of breakout eruptive flares. The simulations allow us to resolve in detail the generation and evolution of large-scale flux ropes as a result of sporadic and patchy reconnection in the flare current sheet. Our results show that the initial energy of particles can be increased by 2-5 times in a typical contracting island, before the island reconnects with the underlying arcade. Therefore, particles need to transit only from 3-7 islands to increase their energies by two orders of magnitude. These macroscopic regions, filled with a large number of particles, may explain the large observed rates of energetic electron production in flares. We conclude that this mechanism is a promising candidate for electron acceleration in flares, but further research is needed to extend our results to 3D flare conditions.

Energetic particle acceleration↗
NASA NTRS1981

Kinetics of the gas-phase reaction between hydroxyl and carbonyl sulfide over the temperature range 300-517 K

By use of a discharge-flow resonance-fluorescence method the rate constant for the title reaction has been measured at five temperatures in the range 300-520 K. The Arrhenius expression is k(OH + OCS) = (1.3 + or - 0.3) x 10 to the -12th exp/-(2300 + or - 100)/T/ cu cm/s. Mass spectrometry has been used to detect the product HS and to collect some information about its reactivity. This study has carefully avoided the pitfalls associated with possible photolysis of reactants and complications due to H2S impurity in carbonyl sulfide that may have marred previous studies. This study has confirmed that the rate constant for this reaction is so much lower than the value originally used in computer modeling of the upper and lower atmosphere that conclusions about the relative importance of photolysis of OCS and of the reaction OH + OCS in the stratosphere must now be reassessed. The reaction OH + OCS has little significance for atmospheric chemistry.

Leu, M.-T.↗
DOE OSTI2025

Enabling Low-Temperature (LTP) Ignition Technologies for Multi-Mode Engines through the Development of a Validated High-Fidelity LTP Model for Predicative Simulations Tools

The goal of multi-mode engine architectures is to extend current lean-burn dilution limits with renewable fuels, which requires spark plugs to deposit high energies (hundreds of mJ) in order to initiate ignition and complete combustion. At elevated energy deposition rates, spark plugs experience increased electrode erosion and thermal losses, which ultimately shortens the spark-plug lifetime and lowers ignition efficiency. As such, in order to safeguard the efficiency gains of multi-mode concepts, new and improved ignition technologies are required. Recently, non-equilibrium low-temperature plasmas (LTP) have been shown to promote energy-efficient ignition via quenching and transport of electronically excited atoms and molecules, selective radical production and fast heating of hydrocarbon/air mixtures [1-2]. Thus, LTP is seen as a technology that can potentially improve the energy extraction efficiency of fuels, while enabling kinetically controlled combustion modes towards fuel leaner conditions to realize current DOE VTO goals of improving the sustainability of future mobility [3]. Although many previous studies have demonstrated the efficacy of plasma-assisted ignition to enhance combustion, the detailed enhancement mechanisms remain largely unknown, especially for oxygenated fuels and at elevated pressures that are most relevant to practical engine conditions. These barriers hinder the development of accurate and comprehensive numerical models that seek to describe LTP-based ignition in existing engine design software tools and methods. Current state-of-the-art simulation capabilities for LTP ignition systems are in need of improvements since they deliver qualitative results only due to important limitations of existing approaches. Firstly, validated kinetic models with elementary steps for plasma discharges in oxygenated fuel/air mixtures of relevance to the transportation sector are required. Such kinetic models do not exist at present and will be developed and validated within this project. Secondly, plasma discharges and reactive mixture ignition are multi-scale, unsteady processes requiring high-performance numerical methods and software that execute efficiently on DOE supercomputers. Such software does not exist at present and will be developed and applied to practical LTP ignition scenarios as part of this project. Thirdly, experimental databases that are tailored to serve as benchmark in support of the development of predictive computational models of LTP ignition do not exist and will be part of this project.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2026

Efficient Low-Temperature Direct Lithium Extraction from Chloride Brines Enabled by High-Capacity Sorbent

The demand for lithium, a key component in rechargeable batteries for electric vehicles and renewable energy storage systems, has surged in recent years. Meeting this demand requires efficient extraction methods that are both environmentally friendly and economically viable. This study investigates the utilization of the high-capacity sorbent amorphous aluminum hydroxide for enabling efficient direct lithium extraction at low temperatures. Traditional extraction methods often involve acid-leaching and energy-intensive processes that are not only expensive but also environmentally taxing. In contrast, our approach leverages the exceptional sorption properties of amorphous aluminum hydroxide to facilitate lithium extraction directly from brine, achieving extraction efficiencies of 94.4% in case 1 and 96.2% in case 2 at low temperatures. Kinetic modeling using the Avrami–Erofe’ev framework reveals a nucleation-growth mechanism ( n = 0.71, k = 0.131 h –1 ), providing quantitative insights into the solid-state phase transformation process. This method significantly reduces energy consumption and minimizes the environmental footprint. Through systematic experimentation and optimization, we demonstrate the effectiveness and scalability of our approach, highlighting its potential to revolutionize lithium extraction processes. Our findings highlight the potential of high-capacity sorbents, particularly amorphous aluminum hydroxide toward sustainable lithium production, contributing to the advancement of clean-energy technologies.

anions↗
DOE OSTI2025

Thermodynamic and Kinetic Mechanisms Governing the Synthesis of Nickel-Poor Cathodes

A deeper understanding of the thermodynamics and kinetics governing the lithiation and layering mechanisms of NMC cathode materials (LiNixMnyCozO 2 , where x + y + z = 1) offers valuable insights for enhancing synthesis methods and improving cathode performance. By employing atomistic and mesoscale approaches informed by in situ powder X-ray diffraction (PXRD) experiments, critical parameters for comprehending lithiation and layering processes and reaction rates were identified. The mesoscale approach captured the evolution of the phases and crystallite size observed in the in situ PXRD, revealing the differences in reaction rates with the use of different lithium salts and starting precursors. Ab initio molecular dynamics (AIMD) underscored the importance of vacancies and structural defects in promoting ion mobility and facilitating the nucleation of a layered domain. This nucleation disrupts the symmetry of disordered phases, ultimately creating a strained phase that serves as a buffer between layered and disordered regions. The lithiation and layering processes reflect a dynamic balance between the thermodynamic drive for a low-energy layered structure and the kinetic of diffusion, which is influenced by temperature and lithium vacancy concentration. Overall, reaction mechanisms are driven by the inherent defects of the intermediate phase that differ for NMC cathode materials. The lithium salts impact the rates of lithiation and layering, with a much slower process for Li 2 CO 3 .

25 ENERGY STORAGE↗
DOE OSTI2026

Stoichiometrically-informed symbolic regression for extracting chemical reaction mechanisms from data

A data-driven computational method is introduced to extract chemical reaction mechanisms from time series chemical concentration data. It is realized through the use of dynamic symbolic regression in which a sparse analytical form for a dynamical system is discoverable from the underlying data. We specifically develop the stoichiometrically-informed symbolic regression (SISR) method to address a standing challenge in complex chemical reaction networks: given a time-series dataset of concentrations of several components, what is the mechanism and the associated rate constants? SISR finds the optimal mechanism, kinetic equations and rate constants by combining differential optimization with a genetic optimization approach that searches a symbolic space of possible reaction mechanisms. Use of SISR in several paradigmatic examples spanning linear and nonlinear reaction schemes results in excellent agreement between true and predicted mechanisms, including when the method is applied to noisy data. The advantages of a stoichiometrically-informed approach such as SISR to address reaction discovery is illustrated through comparison with the use of generic state-of-the-art data-driven approaches.

36 MATERIALS SCIENCE↗
NASA NTRS1999

Protein kinetics during and after long-duration spaceflight on MIR

Human spaceflight is associated with a loss of body protein. Bed rest studies suggest that the reduction in the whole body protein synthesis (PS) rate should be approximately 15%. The objectives of this experiment were to test two hypotheses on astronauts and cosmonauts during long-duration (>3 mo) flights on MIR: that 1) the whole body PS rate will be reduced and 2) dietary intake and the PS rate should be increased postflight because protein accretion is occurring. The 15N glycine method was used for measuring whole body PS rate before, during, and after long-duration spaceflight on the Russian space station MIR. Dietary intake was measured together with the protein kinetics. Results show that subjects lost weight during flight (4.64 +/- 1.0 kg, P < 0.05). Energy intake was decreased inflight (2,854 +/- 268 vs. 2,145 +/- 190 kcal/day, n = 6, P < 0.05), as was the PS rate (226 +/- 24 vs. 97 +/- 11 g protein/day, n = 6, P < 0.01). The reduction in PS correlated with the reduction in energy intake (r2 = 0.86, P < 0.01, n = 6). Postflight energy intake and PS returned to, but were not increased over, the preflight levels. We conclude that the reduction in PS found was greater than predicted from ground-based bed rest experiments because of the shortfall in dietary intake. The expected postflight anabolic state with increases in dietary intake and PS did not occur during the first 2 wk after landing.

STS-40 Shuttle Project↗
DOE OSTI2025

Simulation Models for Exploring Magnetic Reconnection

Simulations have played a critical role in the advancement of our knowledge of magnetic reconnection. However, due to the inherently multiscale nature of reconnection, it is impossible to simulate all physics at all scales. For this reason, a wide range of simulation methods have been crafted to study particular aspects and consequences of magnetic reconnection. This article reviews many of these methods, laying out critical assumptions, numerical techniques, and giving examples of scientific results. Plasma models described include magnetohydrodynamics (MHD), Hall MHD, Hybrid, kinetic particle-in-cell (PIC), kinetic Vlasov, Fluid models with embedded PIC, Fluid models with direct feedback from energetic populations, and the Rice Convection Model (RCM).

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1973

Turbulent kinetic energy equation and free mixing

Calculation of free shear flows was carried out to investigate the usefulness of several concepts which were previously successfully applied to wall flows. The method belongs to the class of differential approaches. The turbulence is taken into account by the introduction of one additional partial differential equation, the transport equation for the turbulent shear stress. The structure of turbulence is modeled after Bradshaw et al. This model was used successfully in boundary layers and its applicability to other flows is demonstrated. The work reported differs substantially from that of an earlier attempt to use this approach for calculation of free flows. The most important difference is that the region around the center line is treated by invoking the interaction hypothesis (concerning the structure of turbulence in the regions separated by the velocity extrema). The compressibility effects on shear layer spreading at low and moderate Mach numbers were investigated. In the absence of detailed experiments in free flows, the evidence from boundary layers that at low Mach numbers the structure of turbulence is unaffected by the compressibility was relied on. The present model was tested over a range of self-preserving and developing flows including pressure gradients using identical empirical input. The dependence of the structure of turbulence on the spreading rate of the shear layer was established.

Morel, T.↗