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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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All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Importance of Higher Fidelity Model Geometries during Optimization of Critical Experiments

PARADIGM, PARallel Approach of Differential and InteGral Measurements, is a cross-collaborative effort at Los Alamos National Laboratory between nuclear data theorists, differential and integral experimenters, as well as machine learning statisticians to tackle uncertainties in the intermediate region of 239 Pu. In essence, the idea behind PARADIGM is to remove the linear conceptualization of the nuclear data pipeline, shown in Figure 1, and replace it with a far more parallelized approach. The novel approach leverages machine learning to guide which differential measurements and integral experiments will result in the largest decrease in uncertain ties for a nuclide reaction pair in a given energy range. The concept builds off earlier work, EUCLID, which focused on the fast region of 239 Pu. The practical benefit of having evaluation, differential measurement, and integral experiment personnel in collaboration with machine learning is to represent the entire nuclear data in one snapshot. This enable large reduction in the time to deliver improved nuclear data, which using the PARADIGM approach could be done in 3 years. A general outline of PARADIGM and specific topics are available in other papers. The discussion here will pertain directly to the integral experiment design. More specifically, the process of taking a rough design and transforming it into a finalized neutronic model will be discussed.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2021

Investigation of Scale-Dependent Groundwater/Surface-water Exchange in Rivers by Gradient Self-Potential Logging: Numerical Modeling and Field Experiments

Exchanges of groundwater and surface-water are fundamental to a wide range of water-supply and water-quality management issues but challenging to map beyond the reach scale. Waterborne gradient self-potential (SP) measurements are directly sensitive to water flow through riverbed sediments and can be used to infer exchange locations, direction (gain versus loss), scale, and relative changes, but to date applications to river corridor hydrology are limited. Numerical modeling and field experiments were therefore performed herein, each emphasizing waterborne gradient SP logging for identifying and locating focused vertical groundwater discharge (surface-water gain) and recharge (surface-water loss) in a river. Two and three-dimensional numerical models were constructed to simulate the polarities, appearances, and peak amplitudes of streaming-potential and electric-field anomalies on a riverbed and in the surface-water that were attributable to steady-state vertical fluxes of groundwater through high-permeability conduits in the riverbed. Effects of varied hydraulic length-scale of exchange and surface-water depth were tested through numerical modeling. Modeling results aided in data acquisition and interpretation for three repeated field experiments performed along a 1.5–2.0 km reach of the Quashnet River in Cape Cod, Massachusetts, where focused, meter-scale groundwater discharges occur at discrete locations within otherwise ubiquitous and more diffuse groundwater upwelling conditions. Strong gradient SP anomalies were repeatedly measured in the Quashnet River at previously confirmed locations of focused groundwater discharge, showing the efficacy of waterborne gradient SP logging in identifying and characterizing groundwater/surface water exchange dynamics at multiple river network scales.

Engineering↗
DOE OSTI2019

Postirradiation Examination of the ATF-1 Experiments - 2019 Status

A collaborative effort of the Advanced Fuels Campaign together with industry consortia is focused on the development of enhanced accident tolerant fuels for Light Water Reactors (LWRs). The scoping studies, referred to as ATF-1 irradiations, are being performed in the Advanced Test Reactor of Idaho National Laboratory using drop-in style irradiations. The Post-Irradiation Examinations (PIEs) of ATF-1 began in 2017 and continued in 2019. This report describes the results of examinations on ATF-1 irradiations designed to test the performance of advanced iron-based cladding, including compatibility of FeCrAl with UO2, and ATF-1 irradiation of U3Si5. Two rodlets with commercial iron-based cladding and UO2 pellets have been irradiated to low burnup (i.e., < 20 GWd/tHM). The first rodlet had an Alloy33 cladding, while the other had a Kanthal APMT® cladding. The performed PIEs were focused on the determination of fuel microstructure, evaluation of fuel-cladding interaction and irradiation-induced variations of cladding mechanical properties. For both rodlets, no significant changes in the cladding hardness were measured, and the cladding hoop strain remained limited. Gamma tomography revealed no Cs axial migration as expected for LWR fuel, but significant cesium radial migration, which was induced by thermal migration consequent to high irradiation temperatures. Microstructure analyses revealed formation of secondary phases along the pellet rim of samples from both rodlets. No wastage or extensive chemical interaction between the fuel and the internal wall of the cladding was observed, suggesting that the secondary phases accumulated at the pellet rim might be due to formation of Cs-U-O compounds. However, further advanced PIEs are necessary to finally confirm this hypothesis. Optical microscopy analysis of the rodlet designed by Oak Ridge National Laboratory to evaluate the interaction between UO2 and various FeCrAl alloys revealed no extensive interaction in all the samples irradiated in the rodlet. Localized defects, namely circular pitting and cracks of a few tents of microns, were observed on the FeCrAl disc surfaces in some of the diffusion couples. These defects might be surface fabrication defects rather than irradiation-induced localized corrosion, but chemical analyses are needed to determine whether accumulation of corrosive fission products are causing enhanced interaction. Both non-destructive and destructive PIEs were collected on a rodlet containing U3Si5 fuel. The rodlet had extremely low fission gas release, similar to previously analyzed U3Si2 rodlets. Gamma tomography revealed thermo-migration of fission product ruthenium toward the center of the fuel pellet. The fuel microstructure resembles the as-fabricated microstructure, showing extensive microcracking related to the phase transition at 450°C. Two types of secondary phases were observed, which could either be due to segregation and precipitation of fission products or to UN impurities from fabrication. Finally, the current status of PIE on other ATF-1 irradiations will be discussed. These irradiations include UN-U3Si5 rodlets, UN-U3Si2 rodlets and an additional test with U3Si2 fuel.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2014

Experimental sloshing pressure impacts in ensemble domain: Transient and stationary statistical characteristics

The present paper focuses on the analysis of impact pressure registrations from repeated model scale sloshing experiments under harmonic rotational excitation. A series of more than 100 experiments, each one encompassing more than 100 impact events, has been conducted seeking the highest feasible repeatability. Different excitation periods, that cover the main features of the impact dynamics, have been considered in a preliminary screening, describing the main features of the impact dynamics. Since, even under a nominally deterministic excitation, the pressure at each impact is characterized by a high variability, a statistical approach is used treating the impact pressure as a stochastic process. For one selected excitation period, the statistical analysis focuses on the ensemble distribution of the maximum pressure during each impact event. Particular attention is given to the evolution of such distributions, in order to detect the variations in the statistical characteristics of the process. This is achieved by, first, identifying the presence and the length of the transient phase and, second, by characterizing the process at stationary state. The statistics of impact pressure for different peaks are discussed mostly in the ensemble domain. Linking the latter with the time domain analysis is made by checking that the problem can be considered “practically ergodic.” The “practical ergodicity” of the process is dealt with by checking to what extent steady state ensemble statistical information can be obtained from a single long run experiment. Statistical checks for correlation and independence of maximum impact pressures are also carried out to test the hypothesis of independent identically distributed random variables. The method of analysis presented in this paper through the considered example case is general in nature and is considered to be highly portable. In particular, it is considered to allow for a more thorough understanding of non-deterministic events such as those considered herein, by looking at them from a sound statistical perspective. The thorough description of the whole experimental setup makes the presented data suitable for comparison purposes and for validation of theoretical/numerical approaches.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Recent Experiments At Ndcx-II: Irradiation Of Materials Using Short, Intense Ion Beams

We present an overview of the performance of the Neutralized Drift Compression Experiment-II (NDCX-II) accelerator at Berkeley Lab, and summarize recent studies of material properties created with nanosecond and millimeter-scale ion beam pulses. The scientific topics being explored include the dynamics of ion induced damage in materials, materials synthesis far from equilibrium, warm dense matter and intense beam-plasma physics. We summarize the improved accelerator performance, diagnostics and results of beam-induced irradiation of thin samples of, e.g., tin and silicon. Bunches with over 3x10^10 ions, 1- mm radius, and 2-30 ns FWHM duration have been created. To achieve these short pulse durations and mm-scale focal spot radii, the 1.2 MeV He+ ion beam is neutralized in a drift compression section which removes the space charge defocusing effect during final compression and focusing. Quantitative comparison of detailed particle-in-cell simulations with the experiment play an important role in optimizing accelerator performance; these keep pace with the accelerator repetition rate of ~1/minute.

Seidl, PA↗
DOE OSTI2018

A detailed reaction mechanism for oxidative coupling of methane over Mn/Na 2 WO 4 /SiO 2 catalyst for non-isothermal conditions

Direct production of ethylene from natural gas or other methane sources has proven to be challenging from catalytic, process design and economic perspectives, with no reports of a commercially viable process to date. Understanding of the underlying non-ideal homogeneous and heterogeneous reactions involved could lead to success, enabling utilization of vast natural gas resources as a replacement for petrochemicals. In this regards, an improved reaction mechanism and computational model, validated experimentally, for oxidative coupling of methane (OCM) over a Mn/Na 2 WO 4 /SiO 2 catalyst is developed, taking into account the non-isothermal behavior exhibited by the gas and surface reactions. The reaction mechanism involves detailed gas-phase and surface elementary steps to describe the OCM chemistry and employing a reduced model for computational efficiency. Our model uses laboratory-scale packed-bed reactor experiments for kinetic mechanism development. The modeling and simulation is particularly focused on a one-dimensional packed-bed reactor. The kinetic model is validated over a wide range of experimental conditions. The model-predicted results and their comparisons with the experimental data are presented wide temperature ranges and methane-to-oxygen feed ratios under adiabatic reactor conditions. The kinetic model is first of its kind in which non-isothermal OCM kinetic behavior is captured using detailed gas-phase and heterogeneous reaction kinetics.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Reirradiation of Head and Neck Cancers With Proton Therapy: Outcomes and Analyses

Purpose: Reirradiation of head and neck (H&N) cancer is a clinical challenge. Proton radiation therapy (PRT) offers dosimetric advantages for normal tissue sparing and may benefit previously irradiated patients. Here, we report our initial experience with the use of PRT for H&N reirradiation, with focus on clinical outcomes and toxicity. Methods and Materials: We retrospectively reviewed the records of patients who received H&N reirradiation with PRT from April 2011 through June 2015. Patients reirradiated with palliative intent or without prior documentation of H&N radiation therapy were excluded. Radiation-related toxicities were recorded according to the Common Terminology Criteria for Adverse Events Version 4.0. Results: The conditions of 60 patients were evaluated, with a median follow-up time of 13.6 months. Fifteen patients (25%) received passive scatter proton therapy (PSPT), and 45 (75%) received intensity modulated proton therapy (IMPT). Thirty-five patients (58%) received upfront surgery, and 44 (73%) received concurrent chemotherapy. The 1-year rates of locoregional failure–free survival, overall survival, progression-free survival, and distant metastasis–free survival were 68.4%, 83.8%, 60.1%, and 74.9%, respectively. Eighteen patients (30%) experienced acute grade 3 (G3) toxicity, and 13 (22%) required a feeding tube at the end of PRT. The 1-year rates of late G3 toxicity and feeding tube independence were 16.7% and 2.0%, respectively. Three patients may have died of reirradiation-related effects (1 acute and 2 late). Conclusions: Proton beam therapy can be a safe and effective curative reirradiation strategy, with acceptable rates of toxicity and durable disease control.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2025

Progress in end-to-end optimization of fundamental physics experimental apparata with differentiable programming

In this article we examine recent developments in the research area concerning the creation of end-to-end models for the complete optimization of measuring instruments. The models we consider rely on differentiable programming methods and on the specification of a software pipeline including all factors impacting performance — from the data-generating processes to their reconstruction and the inference on the parameters of interest — along with the careful specification of a utility function well aligned with the end goals of the experiment. Building on previous studies originated within the MODE Collaboration, we focus specifically on applications involving instruments for particle physics experimentation, as well as industrial and medical applications that share the detection of radiation as their data-generating mechanism. This report illustrates the most recent advancements in the area, and outlines, for each of the discussed applications as well as for automatic differentiation itself, ongoing and future work.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2025

VUV Photoionization Dynamics and Reactivity of Heterogeneous Water Clusters

This feature focuses on bridging isolated water and bulk water studies. It assembles experiments and theory on water clusters, mainly probed by vacuum ultraviolet (VUV) radiation, and summarizes what the effects are of intermolecular interactions on both the spectroscopy and the VUV-induced processes in water. In particular, it highlights studies of heterogeneous water clusters─those incorporating other molecular species such as naphthalene, methane, formic acid, and glycerol─which serve as model systems to investigate the fundamental roles of water in hydrogen bonding networks, proton transfer, and astrochemical processes. These mixed clusters provide a platform to revisit the stability of protonated water clusters and compile observations of ionization-induced structural rearrangements and fragmentation, especially in systems involving hydroxyl-rich cosolvents. This feature then explores energy transfer mechanisms in molecular clusters, following VUV photoexcitation. It concludes with potential future directions. First, we investigate excited-state dynamics in molecular clusters through direct probing, complementing the synchrotron studies discussed here. Second, exploring gas-phase molecule evaporation from confined spaces and interfaces using advanced spectroscopic techniques sheds light on these ubiquitous, yet currently debated, molecular processes.

Cluster chemistry↗
DOE OSTI2019

Characteristics of ice nucleating particles in and around California winter storms

A major component of California’s yearly precipitation comes from wintertime atmospheric river (AR) events which bring large amounts of moisture from the tropics up to the midlatitudes. Understanding these systems, specifically the effects of aerosol particles on precipitation associated with these storms, was a major focus of the 2015 Atmospheric Radiation Measurement (ARM) Cloud Aerosol Precipitation Experiment (ACAPEX), which was part of the wintertime CalWater 2015 campaign. The measurement campaign provided sampling platforms on four aircraft, including the ARM Aerial Facility G-1, as well as the NOAA Ronald H. Brown research vessel and at a ground station in Bodega Bay, CA. Measurements of ice nucleating particles (INPs) were made with the Colorado State University (CSU) Continuous Flow Diffusion Chamber (CFDC) aboard the G-1, and aerosol filters were collected on the G-1, at the Bodega Bay site and on the Ronald H. Brown for post-processing via immersion freezing in the CSU Ice Spectrometer. Aerosol composition was measured aboard the G-1 with the Aerosol Time-of-Flight Mass Spectrometer (ATOFMS). Here we present INP concentrations and aerosol chemical compositions during the course of the aircraft campaign. During the AR event we found that marine aerosol was the dominant aerosol type and that marine INPs were dominant at cloud activation temperatures, which is in stark contrast to the dominance of dust INPs during the AR events in the CalWater 2011 campaign.

Levin, Ezra↗
DOE OSTI2025

Recent Experience with the CMS Data Management System

The CMS[1] experiment manages a large-scale data infrastructure, currently handling over 200 PB of disk and 500 PB of tape storage and transferring more than 1 PB of data per day on average between various WLCG[2] sites. Utilizing Rucio[3] for high-level data management, FTS[4] for data transfers, and a variety of storage and network technologies at the sites, CMS confronts inevitable challenges due to the system’s growing scale and evolving nature. Key challenges include managing transfer and storage failures, optimizing data distribution across different storages based on production and analysis needs, implementing necessary technology upgrades and migrations, and efficiently handling user requests. The data management team has established comprehensive monitoring to supervise this system and has successfully addressed many of these challenges. The team’s efforts aim to ensure data availability and protection, minimize failures and manual interventions, maximize transfer throughput and resource utilization, and provide reliable user support. This paper details the operational experience of CMS with its data management system in recent years, focusing on the encountered challenges, the effective strategies employed to overcome them and the ongoing challenges as we prepare for future demands.

Öztürk, Hasan [CERN]↗
DOE OSTI2016

Mapping strain fields induced in Zr-based bulk metallic glasses during in-situ nanoindentation by X-ray nanodiffraction

A pioneer in-situ synchrotron X-ray nanodiffraction approach for characterization and visualization of strain fields induced by nanoindentation in amorphous materials is introduced. In-situ nanoindentation experiments were performed in transmission mode using a monochromatic and highly focused sub-micron X-ray beam on 40 μm thick Zr-based bulk metallic glass under two loading conditions. Spatially resolved X-ray diffraction scans in the deformed volume of Zr-based bulk metallic glass covering an area of 40 × 40 μm{sup 2} beneath the pyramidal indenter revealed two-dimensional map of elastic strains. The largest value of compressive elastic strain calculated from diffraction data at 1 N load was −0.65%. The region of high elastic compressive strains (<−0.3%) is located beneath the indenter tip and has radius of 7 μm.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Hydrodynamic dispersion in thin channels with micro-structured porous walls

Flowand transport within porous- and microtextured-walled channels is relevant to a number of natural and industrial processes. Designing and optimizing the topology of the pores and/or microstructure to achieve target performance at the system scale (or macroscale) is still an open question. In this work, we study whether hydrodynamic dispersion in microfluidic channels with walls structured by obstacles can be modeled by dispersion in channels with porous walls described as continuous porous media of zero or finite permeability. We perform single phase microfluidic non-reactive flow experiments in channels embedded in micropatterns with different topologies. Specifically, we focus on transverse riblets and arrays of pillars as examples of impermeable and permeable obstructions, respectively. We compare the experimental results with three models: 3D pore-scale simulations which resolve the micropattern geometry explicitly and two upscaled models which treat the micropattern as a continuum of zero or finite permeability. This study demonstrates that polydimethylsiloxane micromodels with appropriately patterned surfaces can be successfully employed to validate various continuum-scale modeling approximations in different physical regimes, identified by the order of magnitude of the Peclet number and the obstruction permeability.

Ling, Bowen↗
DOE OSTI2021

Lessons learned from first-principles calculations of transition metal oxides

Transition metal oxides (TMOs) are an important class of materials with diverse applications, ranging from memristors to photoelectrochemical cells. First-principles calculations are critical for understanding these complex materials at an atomic level and establishing relationships between atomic and electronic structures, particularly for probing quantities difficult or inaccessible to experiment. Here, we discuss computational strategies used to understand TMOs by focusing on two examples, a photoanode material, BiVO4, and an oxide for low-power electronics, La1−xSrxCoO3. We highlight key aspects required for the modeling of TMOs, namely, the descriptions of how oxygen vacancies, extrinsic doping, the magnetic state, and polaron formation impact their electronic and atomic structures and, consequently, many of the observed properties.

Vo, Hien (ORCID:0000000158315599)↗
DOE OSTI2021

Quantum networks based on color centers in diamond

With the ability to transfer and process quantum information, large-scale quantum networks will enable a suite of fundamentally new applications, from quantum communications to distributed sensing, metrology, and computing. This Perspective reviews requirements for quantum network nodes and color centers in diamond as suitable node candidates. We give a brief overview of state-of-the-art quantum network experiments employing color centers in diamond and discuss future research directions, focusing, in particular, on the control and coherence of qubits that distribute and store entangled states, and on efficient spin–photon interfaces. We discuss a route toward large-scale integrated devices combining color centers in diamond with other photonic materials and give an outlook toward realistic future quantum network protocol implementations and applications.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2024

Automated Bayesian high-throughput estimation of plasma temperature and density from emission spectroscopy

Here, this paper introduces a novel approach for automated high-throughput estimation of plasma temperature and density using atomic emission spectroscopy, integrating Bayesian inference with sophisticated physical models. We provide an in-depth examination of Bayesian methods applied to the complexities of plasma diagnostics, supported by a robust framework of physical and measurement models. Our methodology is demonstrated using experimental observations in the field of magneto-inertial fusion, focusing on individual and sequential shot analyses of the Plasma Liner Experiment at LANL. The results demonstrate the effectiveness of our approach in enhancing the accuracy and reliability of plasma parameter estimation and in using the analysis to reveal the deep hidden structure in the data. This study not only offers a new perspective of plasma analysis but also paves the way for further research and applications in nuclear instrumentation and related domains.

Bayesian inference↗
DOE OSTI2015

Femtosecond-laser fabrication of cyclic structures in the bulk of transparent dielectrics

We report the results of the experiments on developing precision micromachining technology, obtained under the conditions of focusing the pulses of a femtosecond (FS) laser into the volume of a transparent material, which is important, particularly, in the processing of biomaterials in ophthalmology. The implementation conditions and some characteristic features of the special regime of micromachining are determined, when at a definite relation between the sample scanning velocity and the repetition rate of FS pulses the region, destroyed by the laser radiation, is shifted along the optical axis towards the objective and back, forming cyclic patterns inside the sample. It is supposed that the main causes of the damage region shift are the induced modification of the refractive index and the reduction of the damage threshold due to the change in the material density and structure in the microscopic domain, adjacent to the boundary of the cavity produced by the previous pulse. The results of the performed study with the above regime taken into account were used in the technology of precision cutting of crystals, glasses and polymers. The best quality of the cut surface is achieved under the conditions, eliminating the appearance of the cyclic regime. In the samples of polycarbonate, polymethyl methacrylate and fused silica the cylindrical cavities were obtained with the aspect ratio higher than 200, directed along the laser beam, and microcapillaries with the diameter 1 – 2 μm in the direction, perpendicular to this beam. (interaction of laser radiation with matter)

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

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