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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Predictive turbulence-driven flux model of scrape-off layer widths across confinement regimes in tokamaks

Reliable scrape-off layer (SOL) profile decay lengths predictions are needed to design and operate future tokamaks. The present manuscript describes a new model based on turbulent transport that is able to predict SOL widths for both L-mode and H-mode plasmas. The model is based upon the sheared-spectral filament paradigm (Peret et al (WEST Team) 2022 Phys. Plasmas 29 072306), however, incorporating the effects of thermal transport in order to calculate the parallel heat fluxes. The effects of magnetic shear and ExB shear on the cross-field transport are crucial to explain the shorter SOL decay lengths found in H-mode. The model is validated against a database of thousands of DIII-D L-mode and H-mode SOL profiles. We also calculate SOL decay length predictions in terms of plasma and engineer control parameters, which are in agreement with the multi-machine empirical H-mode scaling (Eich et al (ASDEX Upgrade Team and JET EFDA Contributors) 2013 Nucl. Fusion 53 093031), however, with an additional device geometry dependence. ITER SOL width predictions by the model are 3 times higher than the empirical scaling.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2026

Influence of fabrication on microstructure and heat affected zone width in weldments of nuclear reactor pressure vessel steel

Advanced manufacturing routes such as electron beam welding and powder metallurgy with hot isostatic pressing are increasingly used across energy and aerospace industries, where the reliable prediction of weld behavior and heat affected zone (HAZ) evolution is critical. This study examines how fabrication routes and post-weld heat treatments influence phase distribution, crystallite size, microstrain, and dislocation density in nuclear reactor pressure vessel steels using synchrotron X-ray diffraction (SXRD). Retained austenite occurs only in samples that did not undergo austenitization, whereas an austenitizing heat treatment fully eliminates retained austenite and produces a more uniform microstructure across the weldment in terms of phase fraction, dislocation density, and microstrain. The Rosenthal solution underestimates the HAZ width for powder metallurgy samples. A newly proposed modified Rosenthal solution, reducing density by accounting for porosity, matches the SXRD-measured HAZ width with a 0.65% error. Structure–property correlations reveal that dislocation density correlates strongly with nanohardness in homogenous microstructures, while in heterogenous weldments nanohardness is further influenced by the presence of dissimilar phase boundaries. These findings provide new insight into the thermal and microstructural response of powder metallurgy fabricated steels and offer a framework for optimizing welding procedures and heat treatments in advanced manufacturing applications.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Measurement of the Z boson invisible width at $\sqrt{s}=13$ TeV with the ATLAS detector

A measurement of the invisible width of the Z boson using events with jets and missing transverse momentum is presented using 37 fb -1 of 13 TeV proton–proton data collected by the ATLAS detector in 2015 and 2016. The ratio of Z → inv to Z → ℓℓ events, where inv refers to non-detected particles and ℓ is either an electron or a muon, is measured and corrected for detector effects. Events with at least one energetic central jet with p T ≥ 110 GeV are selected for both the Z → inv and Z → ℓℓ final states to obtain a similar phase space in the ratio. The invisible width is measured to be 506 ± 2 (stat.) ± 12 (syst.) MeV and is the single most precise recoil-based measurement. The result is in agreement with the most precise determination from LEP and the Standard Model prediction based on three neutrino generations.

13000 GeV-cms↗
DOE OSTI2025

NLO SMEFT electroweak corrections to Higgs boson decays to four leptons in the narrow width approximation

Some of the most precise measurements of Higgs boson couplings are from the Higgs decays to 4 leptons, where deviations from the Standard Model predictions can be quantified in the framework of the Standard Model effective field theory (SMEFT). In this work, we present a complete next-to-leading order (NLO) SMEFT electroweak calculation of the rate for H → ℓ + ℓ − Z which we combine with the NLO SMEFT result for Z → ℓ + ℓ − to obtain the NLO rate for the H → 4 lepton process in the narrow width approximation. The NLO calculation provides sensitivity to a wide range of SMEFT operators that do not contribute to the rate at lowest order and demonstrates the importance of including correlations between the effects of different operators when extracting limits on SMEFT parameters. We show that the extraction of the Higgs trilinear coupling from the decay H → ℓ + ℓ − Z , Z → ℓ + ℓ − in the narrow width approximation strongly depends on the contributions of other operators that first occur at NLO. Published by the American Physical Society 2025

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Separated reactant mix width across diffusion-dominated and hydrodynamically dominated interface mix in inertial confinement fusion implosions

Diffusion-dominated mix in inertial confinement fusion (ICF) is characterized where the majority of the mix occurs in the immediate fuel-shell interface while hydrodynamic-dominated mix pulls shell material from farther away into the central fuel. A thin (150 nm) separated reactants ICF mix platform is highly sensitive to the amount of mix from the first micron of shell-fuel interface. This fine-spatial resolution platform has revealed that material mix in moderate convergence ( CR ∼ 12 ) ICF implosions is dominated by a diffusion mechanism. This technique has now been expanded across a set of OMEGA ICF implosions, observing an increase in mix width and mix amount for cooler, slower, and more compressive implosions. Hydrodynamic simulations require a buoyancy-drag mix model to capture the increasing mix width, suggesting a transition between these two mix mechanisms. Published by the American Physical Society 2024

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2024

Experimental Determination of 𝛼 Widths of 21 Ne Levels in the Region of Astrophysical Interest: New 17 O +𝛼 Reaction Rates and Impact on the Weak 𝑠 Process

The efficiency of the weak 𝑠 process in low-metallicity rotating massive stars depends strongly on the rates of the competing 17 O ⁡(𝛼,𝑛)⁢ 20 Ne and 17 O ⁡(𝛼,𝛾)⁢ 21 Ne reactions that determine the potency of the 16 O neutron poison. Their reaction rates are poorly known in the astrophysical energy range of interest for core helium burning in massive stars because of the lack of spectroscopic information (partial widths, spin parities) for the relevant states in the compound nucleus 21 Ne . In this Letter, we report on the first experimental determination of the 𝛼-particle spectroscopic factors and partial widths of these states using the 17 O ⁡( 7 Li, 𝑡)⁢ 21 Ne 𝛼-transfer reaction. With these the 17 O ⁡(𝛼, 𝑛)⁢ 20 Ne and 17 O ⁡(𝛼, 𝛾)⁢ 21 Ne reaction rates were evaluated with uncertainties reduced by a factor more than 3 with respect to previous evaluations and the present 17 O ⁡(𝛼, 𝑛)⁢ 20 Ne reaction rate is more than 20 times larger. Finally, the present (𝛼, 𝑛)/(𝛼, 𝛾) rate ratio favors neutron recycling and suggests an enhancement of the weak 𝑠 process in the Zr-Nd region by more than 1.5 dex in metal-poor rotating massive stars.

direct reactions↗
DOE OSTI2026

Measurement of the Higgs boson total decay width using the 𝐻 → 𝑊⁢𝑊 → 𝑒⁢𝜈⁢𝜇⁢𝜈 decay channel in proton-proton collisions at $\sqrt{s} =13$ TeV

The Higgs boson (H) decay width is determined from the ratio of off- and on-shell production of 𝐻 → 𝑊⁢𝑊 → 𝑒⁢𝜈⁢𝜇⁢𝜈 using proton–proton collision data corresponding to an integrated luminosity of 138 fb −1 collected at $\sqrt{s} =13$ TeV by the CMS experiment at the Large Hadron Collider. The off-shell signal strength is measured as 𝜇 off−shell = $1.2^{+0.8}_{−0.7}$. The Higgs boson total decay width is Γ 𝐻 = $3.9^{+2.7}_{−2.2}$ MeV, in agreement with the standard model prediction. The uncertainty in this result represents a factor of 3 improvement over the previous CMS result in this decay channel.

Hayrapetyan, A. [Yerevan Physics Institute]↗
DOE OSTI2024

Measurement of the W-boson mass and width with the ATLAS detector using proton–proton collisions at $\sqrt{s}=7$ TeV

Proton-proton collision data recorded by the ATLAS detector in 2011, at a centre-of-mass energy of 7 TeV, have been used for an improved determination of the W-boson mass and a first measurement of the W-boson width at the LHC. Recent fits to the proton parton distribution functions are incorporated in the measurement procedure and an improved statistical method is used to increase the measurement precision. The measurement of the W-boson mass yields a value of m w = 80,366.5 ± 9.8 (stat.) ± 12.5 (syst.) MeV = 80,366.5 ± 15.9 MeV, and the width is measured as Γ w = 2202 ± 32 (stat.) ± 34 (syst.) MeV = 2202 ± 47 MeV. The first uncertainty components are statistical and the second correspond to the experimental and physics-modelling systematic uncertainties. Both results are consistent with the expectation from fits to electroweak precision data. The present measurement of m w is compatible with and supersedes the previous measurement performed using the same data.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

A Large-Eddy Simulation Study in WRF on Wind over Broadband Waves of Different Directions and Spreading Widths

We use the Weather Research and Forecasting (WRF) Model coupled with moving waves to conduct large-eddy simulations (LESs) of wind over broadband waves with different propagating directions and spreading widths. Our results show that wind-opposing waves can double the form drag, and the wave propagating direction affects the mean wind velocity, velocity variances, and pressure stress. On the other hand, waves with wider spread tend to reduce the form drag in the streamwise direction. Results further indicate that the wave direction can impact the bulk drag coefficient by as much as 25%, while the wave directional spreading width can change it by 5%. Based on our wave-phase-resolved simulations, we demonstrate that the parameterization of sea surface roughness is significantly influenced by the direction of wave propagation relative to the wind, a factor that the commonly used Charnock relation does not account for.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Effects of Central Cut Width on the Dynamical Characteristics of Box Assembly Structure

An investigation into the Box Assembly with Removable Component (BARC) structure is conducted by utilizing computational simulations and experimental structural testing in order to determine the complex dynamical responses instigated by the central cut of the system. Because the dynamics of the BARC system is complex, this study focuses primarily on analyzing the behavior of the box assembly (BA) system. The investigation explores the dynamics of the BA system by varying the central cut widths, ranging from a cut as wide as 0.5” cut to a 0.25” cut system, as well as a 0.1” cut and a system with no cut at all. Experimental testing is performed on each system including a free vibration test using an impact hammer to excite and identify the dominant frequencies of each structure. This testing is followed by pseudo-random vibration tests and swept sinusoidal excitation tests to determine the nonlinear aspects of these systems, such as the possible existence of nonlinear softening, hardening, and/or damping. The results show that nonlinear softening and nonlinear damping are present in each system. The no-cut system demonstrated the highest peak frequencies throughout all the tests, being the most rigid structure. The 0.25” cut system was shown to have the highest peak frequencies among all the cut systems in both the finite elemenet analysis (FEA) and impact testing. This trend did not continue, though, in the random and harmonic testing, possibly due to the added stiffness of the test setup with the slip table and stinger. The results show the importance of accurately measuring the central cut width and how possible geometric uncertainties change the overall dynamical behaviors of complex systems, such as natural characteristics, nonlinear responses, coupling of modes, and oscillating amplitudes.

Padilla, Christopher (ORCID:000900033446732X)↗
NASA NTRS1971

Sub-nanosecond ranging possibilities of optical radar at various signal levels and transmitted pulse widths

The behavior of the photomultiplier is considered, as well as the method of derivation of the photomultiplier output pulse and its relation to the reflected light pulse width and amplitude, and the calibration of range precision and accuracy. Pulsed laser radars with light pulse widths of 30, 3, and 0.1 nanosec a considered, with the 0.1 nanosec system capable of highest precision in several modes of operation, including a high repetition rate, single photoelectron reception mode. An alternate calibration scheme using a fast, triggerable light pulser is described in detail.

Poultney, S. K.↗
NASA NTRS1972

Intensity and half width measurements of the /00 2 - 00 0/ band of N2O.

Measurements of the intensities and half widths of the lines of the (00 2 - 00 0) band of N2O have been made with a spectral resolution better than 0.06/cm. The band intensity has been determined to be 1.29/sq cm per atm at 296 K. The half widths have been measured for both N2 and self broadening.

Margolis, J. S.↗
NASA NTRS1973

Development of a width-modulated pulse rebalance electronics loop for strapdown gyroscopes

A new width modulated pulse rebalance electronics loop was developed for use with strapdown gyroscopes. Advantages of the width modulated binary over the ternary loop are the following: (1) The H-switch is easier to implement; (2) torque is applied in finely quantized increments; (3) the analog-to-digital conversion for data generation is inside the loop and is directly determined by the torque pulse; (4) on part of the loop compensation network bypasses the gyroscope; and (5) the torquer is fed constant power.

Blalock, T. V.↗
NASA NTRS1972

A slope reversal video processor having amplitude and pulse width discrimination.

A timing discriminator whose output is relatively insensitive to input pulse width and amplitude is described. The video-handling technique is known as slope reversal processing and is based on tapped delay line estimation methods. The concept, design, breadboard construction, and preliminary laboratory test results are reviewed. The processor system features (1) a peak input voltage dynamic range of 80x starting at 100 microvolts; (2) a four stage preamplifier/line-driver having a voltage gain of 2400x; (3) a tapped delay-line estimator implemented for slope reversal triggering by differential comparison; (4) a nominal plus or minus 2.5 nsec shift of the output trigger leading edge over the entire input voltage range, (5) up to 7 dB discrimination against pulse widths less than 35 nsec; and (6) up to one order of magnitude reduction in the false alarm rate compared to a constant fraction system.

Hoge, F. E.↗
NASA NTRS1973

On the interpretation of the 'inverse phase effect' for CO2 equivalent widths on Venus

Computations of the equivalent widths of absorption lines as a function of planetary phase angle are made for a homogeneous cloud with particles having the properties (shape, refractive index, and size distribution) deduced from polarimetry of Venus. The computed equivalent widths show an 'inverse phase effect' comparable to that which is observed for CO2 lines on Venus. This result verifies a recent suggestion of Regas et al. that the existence of an inverse phase effect does not by itself imply the presence of multiple layers of scattering particles in the atmosphere of Venus.

Whitehill, L. P.↗
NASA NTRS1974

Measurement of multiplet intensities and noble gas-broadened line widths in the nu 3 fundamental of methane

Presented integrated intensity data at 300 K for J multiplets between P(11) and R(11) in the nu-3 fundamental of C-12 methane are shown to be in good agreement with most previously published pertinent values. Also, line widths measured at 100 K, 130 K, 190 K, 250 K, and 300 K for R(0), R(1), and R(2) broadened by He, Ne, and Ar are presented, and the line-width temperature dependence is discussed for the three cases of broadening.

Varanasi, P.↗