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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 775 records · Page 43
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Soft pions and transport near the chiral critical point

During the expansion of a heavy ion collision, the system passes close to the $\textit{O}$(4) critical point of QCD, and thus the fluctuations of the order parameter $(σ, \overrightarrow{π}$) are expected to be enhanced. In this work, our goal is to compute how these enhanced fluctuations modify the transport coefficients of QCD near the pseudocritical point. We also make a phenomenological estimate for how chiral fluctuations could effect the momentum spectrum of soft pions. We first formulate the appropriate stochastic hydrodynamic equations close to the $\textit{O}$(4) critical point. Then, working in mean field, we determine the correlation functions of the stress tensor and the currents which result from this stochastic real-time theory, and use these correlation functions to determine the scaling behavior of the transport coefficients. The hydrodynamic theory also describes the propagation of pion waves, fixing the scaling behavior of the dispersion curve of soft pions. We present scaling functions for the shear viscosity and the charge conductivities near the pseudocritical point and estimate the absolute magnitude of the critical fluctuations to these parameters and the bulk viscosity. Using the calculated pion dispersion curve, we estimate the expected critical enhancement of soft pion yields, and this estimate provides a plausible explanation for the excess seen in experiment relative to ordinary hydrodynamic computations. Our results motivate further phenomenological and numerical work on the implications of chiral symmetry on real-time properties of thermal QCD near the pseudocritical point.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Liquid fragility maximum in lithium borate glass‐forming melts related to the local structure

Abstract The structure of liquid lithium pyroborate, Li 4 B 2 O 5 ( J = Li/B = 2), has been measured over a wide temperature range by high‐energy X‐ray diffraction, and compared to that of its glass and borate liquids of other compositions. The results indicate a gradual increase in tetrahedral boron fraction from 3(1)% to 6(1)% during cooling from T = 1271(15) to 721(8) K, consistent with the larger N 4 = 10(1)% found for the glass, and literature 11 B nuclear magnetic resonance measurements. van't Hoff analysis based on a simple boron isomerization reaction BØ 3 O 2 – ⇌ BØO 2 2– yields Δ H = 13(1) kJ mol –1 and Δ S = 40(1) J mol –1 K –1 for the boron coordination change from 4 to 3, which are, respectively, smaller and larger than found for singly charged isomers for J ≤ 1. With these, we extend our model for N 4 ( J , T ), nonbridging oxygen fraction f nbr ( J , T ), configurational heat capacity , and entropy S conf ( J , T ) contributions up to J = 3. A maximum is revealed in at J = 1, and shown semi‐quantitatively to lead to a corresponding maximum in fragility contribution, akin to that observed in the total fragilities by temperature‐modulated differential scanning calorimetry. Lithium is bound to 4.6(2) oxygen in the pyroborate liquid, with 2.7(1) bonds centered around 1.946(8) Å and 1.9(1) around 2.42(1) Å. In the glass, n LiO = 5.4(4), the increase being due to an increase in the number of short Li–O bonds.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Raman gain control in optical fibers with orbital-angular-momentum-induced chirality of light

Stimulated Raman scattering is a particularly robust nonlinearity, occurring in virtually every material because its spectral linewidth and associated frequency shift do not typically depend on phases or directions (i.e. wavevectors) of the interacting light beams. In amorphous materials such as glass fibers, Raman bandwidths are large, enabling its use as a broadband gain element. This ubiquity makes it a versatile means for achieving optical amplification or realizing lasers over a large range of pulsewidths at user-defined colors. However, this ease of deploying the effect also presents itself as a stubborn source of noise in fiber-based quantum sources or parasitic emission in fiber lasers. Here, we show that orbital angular momentum carrying light beams experiencing spin-orbit interactions yield novel phase-matching criteria for Raman scattering. This enables tailoring its spectral shape (by over half the Raman shift in a given material) as well as strength (by ∼ 100×) simply by controlling light’s topological charge – a capability of utility across the multitude of applications where modulating Raman scattering is desired.

Liu, Xiao (ORCID:000000032239762X)↗
NASA NTRS1975

Cosmic ray mass and momentum spectra at mountain altitude

A cosmic ray mass spectrometer using a superconducting magnet, digitized wire spark chambers, and a scintillation counter time of flight system, has been operated at an altitude of 2750 meters. The apparatus is most sensitive to charged particles with momentum to mass ratios between 0.2 and 2.0. Results for the momentum spectra of protons and deuterons are presented, as well as upper limits for H-3 and He-3. The reaction nucleon + nucleon yields deuteron + pion accounts for part of the observed deuteron spectrum in the 0.9 to 3 GeV/c region.-

Barber, H. B.↗
NASA NTRS1988

Electrochemical behavior of niobium triselenide cathode in lithium secondary cells

Niobium triselenide cathodes in Li ambient-temperature rechargeable batteries for space applications undergo a topotactic reaction, with three equivalents of Li at high positive potential furnishing high energy density. It also yields good electronic conductivity, a long life cycle, and high diffusivity for Li. An attempt is presently made to characterize the intercalation mechanism between Li and NbSe3 by means of an ac impedance study conducted at various charge stages in the process of SbSe3 reduction. An effort is also made to predict the charge state of NbSe3 nondestructively, on the basis of the impedance parameters.

Ratnakumar, B. V.↗
NASA NTRS2004

The Energy Spectra of Heavy Nuclei Measured by the ATIC Experiment

ATIC (Advanced Thin Ionization Calorimeter) is a balloon-borne experiment to measure the spectra and composition of primary cosmic rays in the region of total energy from 100 GeV to near 100 TeV for Z from 1 to 26. ATIC consists of a pixelated silicon matrix detector to measure charge plus a fully active BGO calorimeter, to measure energy, located below a carbon target interleaved with three layers of scintillator hodoscope. The ATIC instrument had a second (scientific) flight from McMurdo, Antarctica from 12/29/02 to 1/18/03, yielding 20 days of good data. The GEANT 3.21 Monte Carlo code with the QGSM event generator and the FLUKA code with the DPMJET-II event generator were used to convert energy deposition measurements to primary energy. We present the preliminary energy spectra for the abundant elements C, O, Ne, Mg, Si and Fe and compare them with the results of the first (test) flight of ATIC in 2000-01 and with results from the HEAO-3 and CRN experiments.

Panov, A. D.↗
DOE OSTI2026

Identified charged hadron production in Au+Au collisions at $\sqrt{s_{NN}}$ = 54.4 GeV with the STAR detector

Here, we present results on the production of 𝜋±, 𝐾±, 𝑝, and $\bar{𝑝}$ in Au+Au collisions at $\sqrt{𝑠_{N⁢N}}$ = 54.4~GeV using the STAR detector at RHIC, at mid-rapidity (|𝑦|< 0.1). Invariant yields of these particles as a function of transverse momentum are shown. We determine bulk properties such as integrated particle yields (𝑑 ⁢𝑁 /𝑑 ⁢𝑦 ), mean transverse momentum (⟨𝑝 𝑇 ⟩), particle ratios, which provide insight into the particle production mechanisms. Additionally, the kinetic freeze-out parameters (𝑇 kin and ⟨𝛽 𝑇 ⟩), which provide information about the dynamics of the system at the time of freeze-out, are obtained. The Bjorken energy density (𝜖 𝐵⁢𝐽 ), which gives an estimate of the energy density in the central rapidity region of the collision zone at the formation time 𝜏, is calculated and presented as a function of multiplicity for various energies. The results are compared with those from the models such as A Multi-Phase Transport (AMPT) and Heavy Ion Jet INteraction Generator (HIJING) for further insights.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2026

Modulating the Lattice Stability in Sodium-Layered Oxide Cathodes through Inductive Effect

Stability and safety of sodium layered oxide cathodes relative to lithium analogs remain a critical concern, yet its fundamental origin remains poorly understood. Here, we examine the role of sodium – oxygen bond ionicity in governing outgassing by introducing 5% lithium (Li), potassium (K), or both into layered NaNiO 2 (NNO), yielding Na 0.95 Li 0.05 NiO 2 , Na 0.95 K 0.05 NiO 2 , and Na 0.90 Li 0.05 K 0.05 NiO 2 . Online electrochemical mass spectrometry at 4.3 V reveals that K substitution increases gas evolution with similar charge capacity, whereas Li substitution reduces gas evolution by nearly 80% with only a 16% capacity decrease. Capacity-controlled experiments show that NNO must be charged to only 3.8 V (144 mA h g -1 ) to achieve gas evolution comparable to Na 0.95 Li 0.05 NiO 2 charged to 4.3 V (175 mA h g -1 ). These results demonstrate that tuning alkali-metal–oxygen bond ionicity through the inductive effect regulates Ni–O covalency, lattice oxygen stability, and interfacial reactivity, providing design guidance for safer sodium layered oxide cathodes.

25 ENERGY STORAGE↗
DOE OSTI2023

Alpha-heating analysis of burning plasma and ignition experiments on the National Ignition Facility

A recent experiment conducted on the National Ignition Facility (NIF) described in the study by Abu-Shawareb et al. achieved a fusion yield output of 1.3 MJ from ~ 220 kJ of x-ray energy absorbed by the capsule, demonstrating remarkable progress in the field of laser driven inertial confinement fusion. In the study by A. R. Christopherson [“Effects of charged particle heating on the hydrodynamics of inertially confined plasmas,” Ph.D. thesis (2020)], the plasma conditions needed to claim the onset of ignition and burn propagation were outlined and multiple criterion were provided to assess progress in inertial fusion experiments. In this work, we modify the metrics from A. R. Christopherson to accurately calculate performance metrics for indirect-drive experiments on the NIF. We also show that performance metric trends observed in NIF data are consistent with theory and simulations. This analysis indicates that all the identified criterion for ignition and burn propagation have been exceeded by experiment 210 808.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

First Observation of the β3αp Decay of 13 O via β-Delayed Charged-Particle Spectroscopy

The β-delayed proton decay of 13 O has previously been studied, but the direct observation of β-delayed 3⁢α⁢p decay has not been reported. Rare 3⁢α⁢p events from the decay of excited states in 13 N* provide a sensitive probe of cluster configurations in 13 N*. To measure the low-energy products following β-delayed 3⁢αp decay, the Texas Active Target (TexAT) time projection chamber was employed using the one-at-a-time β-delayed charged-particle spectroscopy technique at the Cyclotron Institute, Texas A&M University. A total of 1.9 × 10 5 13 O implantations were made inside the TexAT time projection chamber. Furthermore, a total of 149 3⁢αp events were observed, yielding a β-delayed 3⁢αp branching ratio of 0.078(6)%. Four previously unknown α-decaying excited states were observed in 13 N at 11.3, 12.4, 13.1, and 13.7 MeV decaying via the 3⁢α + p channel.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2026

Denudation, solute export, landscape evolution modeling, and geographic information system data for the East River watershed, Colorado, USA (2020-2024)

This data package contains geographic information system (GIS) layers and tabular datasets associated with the study of lithologic controls on denudation, solute export, carbon-scaling relationships, and transient landscape evolution in the East River watershed near Crested Butte, Colorado, USA. The package includes GIS layers used to produce the Figure 2 map, including drainage, hillshade, lithology, sample locations, and basin polygons, together with comma-separated value (CSV) tables and matching CSV data dictionaries. One group of tables reports sample-level and catchment-level information for river-sediment samples analyzed for in situ-produced cosmogenic beryllium-10 (10Be), including sample names, outlet elevations, geographic coordinates, upstream drainage area, rock-type classes, production-rate scaling scheme, analyzed nuclide, catchment-averaged denudation rates, and associated lower and upper analytical uncertainties. Sample and catchment attributes provide the basis for comparing denudation rates across intrusive, shale, sedimentary, and mixed-lithology settings. A second group of tables reports supporting information for landscape-evolution modeling and the mapped geologic framework of the study area. Included files list parameter values and definitions for the two-phase landscape-evolution simulations, summarize full-domain model erosion fluxes and topographic metrics for different simulation configurations, provide a fixed-area carbon-model scaling table, and summarize mapped geologic units within the East River study domain, including geologic code, formation name, lithologic description, mapped area, and lithologic class grouping. Model outputs and geologic summaries support interpretation of transient landscape behavior and its relation to the mapped distribution of shale, intrusive, sedimentary, and surficial units. A third group of tables reports hydrologic and hydrochemical information used to quantify dissolved export from the watershed. Included files provide site-level values for drainage area, mean annual solute export, standard error of annual export, area-normalized solute yield, and equivalent weathering rate for five East River monitoring sites, along with metadata describing the number, sampling cadence, and date range of discharge records and partial and full total dissolved solids observations used in the solute-yield analyses. The package also contains a supplementary daily ion-load time series with daily mean discharge, discharge observation counts, dissolved concentrations, and daily loads for calcium, magnesium, sodium, potassium, chloride, sulfate, nitrate, fluoride, dissolved silica, charge-balance bicarbonate, and total dissolved solids. The package contains GIS files, comma-separated value files (.csv), CSV data dictionaries, a file-level metadata table, a package-tree text file, and a readme text file.

10Be↗
NASA NTRS1972

Oxygen and hydrogen ion densities above Millstone Hill.

Measurements of the vertical flux of oxygen ions, when combined with simultaneous measurements of electron density and of electron and ion temperatures, present a unique opportunity to examine conditions in the topside ionosphere. The measured fluxes and densities may be used directly to evaluate terms in the O+ continuity equation without requiring any assumptions to be made about neutral winds, electric fields, or the ambipolar diffusion coefficient. From observations at Millstone Hill we have, in this way, derived the rate of loss of O+ in the charge-exchange reaction with hydrogen, the rate of photoionization of atomic oxygen, and the rate of loss of O+ in reactions with N2 and O2. In combination with laboratory and theoretical results, these rates can be interpreted to yield number densities of the corresponding neutral species. When the measured fluxes are examined for consistency with measured density gradients and temperature profiles, we find clear evidence of wind-induced or electrodynamic vertical drifts larger than 60 m/sec.

Schunk, R. W.↗
NASA NTRS1987

Atlas of reflectance spectra of terrestrial, lunar and meteoritic powders and frosts from 92 to 1800 nm

The reflectance spectra of powdered samples of selected minerals, meteorites, lunar materials and frosts are presented as an aid in the interpretation of present and future remote sensing data of solar system objects. Spectra obtained in separate wavelength regions have been combined and normalized, yielding coverage from 92 to 1800 nm. Spectral features include reflectance maxima in the far UV region produced by valence-conduction interband transitions, and reflectance minima in the near UV, visible and near IR regions, produced by charge transfer and crystal field transitions. Specific maxima and minima are diagnostic of mineral type and composition; additionally, the minerals present in mixtures such as meteorites and lunar samples can be determined.

Wagner, Jeffrey↗
NASA NTRS1987

The propagation speed of a positive lightning return stroke

The first direct determination of the propagation speed of a lightning return stroke lowering positive charge to ground has been made. This stroke was the third of eight otherwise negative strokes in a triggered lightning flash initiated at the Kennedy Space Center, FL. Two independent optical systems, one photographic and the other photoelectric, yielded common recordings for the third and fourth strokes; the respective two-dimensional return stroke propagation speeds were 1.0 vs 0.93 x 10 to the 8th m/s for the positive (third) stroke and 1.0 vs 1.0 x 10 to the 8th m/s for the fourth stroke. Using fast electric-field data, the positive stroke peak current was estimated to be 21 kA. Photoelectric data only yielded propagation speeds of 1.4, 1.6, 1.2, 1.3, 1.0 and 0.90 x 10 to the 8th m/s for the first, second and fifth through eighth return strokes, respectively.

Idone, Vincent P.↗
NASA NTRS1993

Lifetimes of bacteriochlorophyll fluorescence in Rhodopseudomonas viridis and Heliobacterium chlorum at low temperatures

Fluorescence lifetimes of isolated membranes of Rhodopseudomonas viridis were measured in the temperature range of 77 K to 25 K. At room temperature, the main component of the fluorescence decay of bacteriochlorophyll (BChl) b had a time constant of 50 ps. In contrast to other purple bacteria, the emission at low temperature was spectrally homogeneous and showed essentially single lifetimes of 140 ps at 77 K and 180 ps at 25 K, with the primary electron donor in the oxidized state. Taking into account the relative fluorescence yields with open and closed reaction centers, we arrive at numbers of 125 ps and 215 ps, respectively, for open reaction centers. These numbers are significantly smaller than expected on the basis of measurements of the efficiency of charge separation, perhaps suggesting that the excitation decay in the absence of reaction centers is considerably faster at low temperature than at room temperature. At least four different spectral components with different lifetimes were observed at 25 K in the emission of Heliobacterium chlorum, a short-wavelength component of about 30 ps and three longer-wavelength components of about 100 ps, 300 ps, and 900 ps. This indicates a strong heterogeneity in the emitting pigment, BChl g-808. The component with the shortest lifetime does not appear to be affected by the redox state of the reaction center and might reflect energy transfer to BChl g species which are connected to the reaction center.

NASA Discipline Number 52-30↗
DOE OSTI2025

Recent Advances in Pipeline Integrity for Transporting Blended Hydrogen-Natural Gas

To achieve US decarbonization goals, hydrogen is being considered as an alternative energy source to reduce carbon emissions. Blending hydrogen into existing natural gas pipelines is an intuitive first step to enable near term emission reductions. However, there are numerous challenges and uncertainties that complicate the transition to transporting hydrogen long-distance through existing natural gas pipelines. The main challenge is hydrogen embrittlement (HE), which reduces the ductility, fracture toughness and fatigue resistance of pipeline steels. This work delivers a technical review on HE effects on the material properties of pipeline carbon steels, such as Grade B, X52, X65, X70, X80, and X100. An important aspect of laboratory tests to capture the HE effect is the hydrogen test environment. This includes hydrogen pre-charged specimens tested in air and specimens tested in a hydrogen gas environment. A review of the mechanical properties of pipeline steel in different hydrogen environments determined through tensile testing is given first, which includes HE effects on yield strength, ultimate tensile strength, and ductility for blended hydrogen-natural gas pipelines. Then, the HE effects on fracture toughness and fatigue crack growth resistance are discussed. Last, impacts of HE to pipeline integrity and major technical challenges are discussed.

: Hydrogen Embrittlement↗
DOE OSTI2023

Elucidating Design Rules toward Enhanced Solid-State Charge Transport in Oligoether-Functionalized Dioxythiophene-Based Alternating Copolymers

This study investigates the solid-state charge transport properties of the oxidized forms of dioxythiophene-based alternating copolymers consisting of an oligoether-functionalized 3,4-propylenedioxythiophene (ProDOT) copolymerized with different aryl groups, dimethyl ProDOT (DMP), 3,4-ethylenedioxythiophene (EDOT), and 3,4-phenylenedioxythiophene (PheDOT), respectively, to yield copolymers P(OE3)-D, P(OE3)-E, and P(OE3)-Ph. At a dopant concentration of 5 mM FeTos 3 , the electrical conductivities of these copolymers vary significantly (ranging between 9 and 195 S cm –1 ) with the EDOT copolymer, P(OE3)-E, achieving the highest electrical conductivity. UV–vis–NIR and X-ray spectroscopies show differences in both susceptibility to oxidative doping and extent of oxidation for the P(OE3) series, with P(OE3)-E being the most doped. Wide-angle X-ray scattering measurements indicate that P(OE3)-E generally demonstrates the lowest paracrystallinity values in the series, as well as relatively small π–π stacking distances. The significant (i.e., order of magnitude) increase in electrical conductivity of doped P(OE3)-E films versus doped P(OE3)-D or P(OE3)-Ph films can therefore be attributed to P(OE3)-E exhibiting both the highest carrier ratios in the P(OE3) series, along with good π–π overlap and local ordering (low paracrystallinity values). Furthermore, these trends in the extent of doping and paracrystallinity are consistent with the reduced Fermi energy level and transport function prefactor parameters calculated using the semilocalized transport (SLoT) model. Observed differences in carrier ratios at the transport edge (c t ) and reduced Fermi energies [η(c)] suggest a broader electronic band (better overlap and more delocalization) for the EDOT-incorporating P(OE3)-E polymer relative to P(OE3)-D and P(OE3)-Ph. Ultimately, we rationalize improvements in electrical conductivity due to microstructural and doping enhancements caused by EDOT incorporation, a structure–property relationship worth considering in the future design of highly electrically conductive systems.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

On the use of charged particles to characterize precipitation in irradiated reactor pressure vessel steels with a wide range of compositions

Nuclear reactor lifetimes may be limited by nano-scale Cu-Mn-Ni-Si precipitates (CRPs and MNSPs) that form under neutron irradiation (NI) of pressure vessel (RPV) steels, resulting in hardening and ductile to brittle transition temperature increases (embrittlement). Physical models of embrittlement must be based on characterization of precipitation as a function of the combination of metallurgical and irradiation variables. Here we focus on rapid and convenient charged particle irradiations (CPI) to both: a) compare to precipitates formed in NI; and, b) use CPI to efficiently explore precipitation in steels with a very wide range of compositions. Atom probe tomography (APT) comparisons show NI and CPI for similar bulk steel solute contents yield nearly the same precipitate compositions, albeit with some differences in their number density, size and volume fraction (f) dose (dpa) dependence. Yet, the overall precipitate evolutions are very similar. Advanced high Ni (>3 wt%) RPV steels, with superior unirradiated properties, were also investigated at high CPI dpa. For typical Mn contents, MNSPs have Ni 16 Mn 6 Si 7 or Ni 3 Mn 2 Si phase type compositions, with f values that are close to the equilibrium phase separated values. In contrast, in steels with very low Mn and high Ni, Ni 2-3 Si silicide phase type precipitate compositions are observed; and when Ni is low, the precipitate compositions are close to the MnSi phase field. Low Mn significantly reduces, but does not eliminate, precipitation in high Ni steels. A comparison of dispersed barrier model predictions with measured hardening data suggests that the Ni-Si dominated precipitates are weaker dislocation obstacles than the G phase type MNSPs.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗