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At least 307 records · Page 17

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DOE OSTI2023

Utilizing grid–supportive load response to shape resilient frequency control of the power grid

The increasing penetration of renewable energy sources and the retirement of conventional generation units have decreased system inertia, making power systems more vulnerable to resilience and stability issues. To address this problem, this paper proposes a novel approach using grid-supportive loads (GSLs) to provide a fast and concise primary frequency response and a deep deterministic policy gradient agent-based secondary controller to restore the system frequency to the nominal value. The proposed method is evaluated on the single-area and multi-area test systems. The simulation results demonstrate that using GSLs enhances the power system's stability and resilience. Compared to conventional controllers, the frequency nadir is improved with GSLs. Additionally, the proposed method effectively enhances resilience even with high penetration. These findings indicate that the proposed approach can improve the resilience and stability of power systems and provide a promising solution for future power systems. The results of this study underscore the importance of utilizing innovative approaches to enhance the stability and resilience of power systems in the context of high penetration of renewable energy sources and the retirement of conventional generation.

24 POWER TRANSMISSION AND DISTRIBUTION↗

DOE OSTI2023

Resonant dynamics of one-side multipactor on dielectric

Breakdown of dielectric radio frequency (RF) windows is an important issue for particle accelerators and high-power RF sources. One of the common reasons for RF window failure is the multipactor on a dielectric surface. The multipactor may be responsible for excessive heating of the dielectric and discharge of charges that accumulated in the ceramic due to secondary emission. In this study, comprehensive self-consistent particle-in-cell simulations with space charge effect were performed. This was to better understand the dynamic of one-side multipactor development and floating potential on the dielectric induced by the emission. The important correlations between the multipactor parameters at saturation, the secondary emission properties of dielectric, and the applied RF field parameters have been found, which led to the conclusion that the dynamics of one-side multipactor on dielectric is a resonant phenomenon.

43 PARTICLE ACCELERATORS↗

DOE OSTI2022

Multiphysics FISPACT-II and TENDL-2019 simulation: neutron-induced damage metrics

Nuclear interactions can be the source of atomic displacement, irradiation-induced defects and transmutation in structural materials. Such quantities are derived from, or can be correlated to, nuclear kinematic simulations of primary atomic energy distributions spectra and the quantification of the numbers of secondary defects produced per primary as a function of the available recoils, residual and emitted, energies. Recoil kinematics of neutral, residual, gas, proton, alpha particle emissions are now more rigorously treated based on recent, complete and enhanced nuclear data parsed in state-of-the-art processing tools. Defect production metrics are the starting point in the complex problem of correlating and simulating the behaviour of materials under irradiation, as experimental information is rare or scattered. Detailed, segregated primary knock-on-atom metrics are now becoming available as the starting point of further simulation processes of isolated and clustered defects in material lattices. This allows more materials, lattices, neutron incident energy ranges, and irradiation conditions to be explored with sufficient data to adequately cover both standard and novel applications and materials: the broader reactor applications landscape. The damage metrics of of materials are systematically explored under typical but different reactor's type environment. The inventory code FISPACT-II combined with the enhanced nuclear data forms of the TENDL-2019 libraries allow one to not only calculate dpa from mostly scattering events but to also properly predict gas production, nuclear heating and transmutation under the same conditions.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

DOE OSTI2024

Effects of delta ray electrons on measurement uncertainties of harp system

A harp system, which is a multi-wire beam profile monitoring (MWPM) system, is planned upstream of the spallation target to make in situ calibration of beam current density configuration on the target along with beam imaging from luminescent coating on the beam entrance window at the Second Target Station (STS) of the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL). This beam interception-based beam diagnostics system on the target will be used to ensure that the maximum beam loads on the target are within the design range during neutron production. Current design of the harp consists of three layers of measurement wires each of which is sandwiched between voltage biasing wire planes. The signal obtained from each measurement wire layer is disturbed by secondary electrons (SE) and delta rays produced by beam-matter interactions in neighboring wires and ionization of residual gases in accelerator vacuum. While the backgrounds from SE can be suppressed by voltage biasing, the delta-ray electrons with kinetic energies above keV ranges overcome the electric potential bias. In this paper, we study the effects of delta-rays on the measurement uncertainties of MWPM using the particle transport simulation code FLUKA. Furthermore, the cases where the harp system is installed in the proximity of a large delta ray sources such as proton beam window or in the core vessel filled with sub-atmospheric gas have been studied.

Lee, Yong Joong↗

DOE OSTI2021

Advanced focusing system for secondary electrons in a bunch shape monitor

Non-destructive measurements of longitudinal beam profile in non-relativistic hadron accelerators are usually performed with Bunch Shape Monitors that utilize secondary electron emission to reproduce the shape of a primary ion beam. The existing devices, however, have poor electron collection efficiency from the wire and are limited to one dimensional measurements of the phase coordinate. Here, we present the development of a bunch shape monitor with improved performance for proton beams to be used in the Spallation Neutron Source accelerator. This improvement was achieved by adding focusing optics between the wire and the entrance slit, which will also allow measurements over a much higher dynamic range. Here we present the design, simulation and experimental test results of the developed new electron beam guidance system for the existing SNS bunch shape monitor that allowed significant improvement in the collection efficiency.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2023

Antibacterial and antioxidant activities of Streptomyces sp. strain FR7 isolated from forest soil

Abstract Actinomycetes produce secondary metabolites with many bioactivities such as antimicrobial, which can be useful as alternatives against resistant bacterial strains. Therefore, the screening of new habitats is likely to provide new strains with high potential. In this work, the antimicrobial capacity was used to select Streptomyces sp. strains isolated from Raf Raf forest (Tunisia). From the strain displaying higher activity, FR7, an ethyl acetate extract was prepared under optimized culturing conditions (10 days at 30°C in ISP2 medium with initial pH 8), showing significant antimicrobial activity against Micrococcus luteus and Staphylococcus aureus (MIC = 5 μg ml−1), and Listeria monocytogenes and Pseudomonas aeruginosa (MIC = 20 μg ml−1). The extract displayed strong DPPH radical scavenging activity (IC50 = 1.3 μg ml−1) and protection of yeast cells from H2O2-induced oxidative stress determined by flow cytometry with dichlorofluorescein diacetate. The crude extract showed the presence of polyketides, with methylsalicylic acid as moiety, a large and diverse group of secondary metabolites with a wide range of bioactivities, including antioxidant and antibacterial. Based on 16S RNA gene sequences, strain FR7 was identified as belonging to genus Streptomyces with high resemblance to S. iakyrus. Streptomyces sp. FR7 has great potential as a source of antibacterial and antioxidant metabolites.

Weslati, Imen↗

DOE OSTI2022

Properties, Physiological Functions and Involvement of Basidiomycetous Alcohol Oxidase in Wood Degradation

Extensive research efforts have been devoted to describing yeast alcohol oxidase (AO) and its promoter region, which is vastly applied in studies of heterologous gene expression. However, little is known about basidiomycetous AO and its physiological role in wood degradation. This review describes several alcohol oxidases from both white and brown rot fungi, highlighting their physicochemical and kinetic properties. Moreover, the review presents a detailed analysis of available AO-encoding gene promoter regions in basidiomycetous fungi with a discussion of the manipulations of culture conditions in relation to the modification of alcohol oxidase gene expression and changes in enzyme production. The analysis of reactions catalyzed by lignin-modifying enzymes (LME) and certain lignin auxiliary enzymes (LDA) elucidated the possible involvement of alcohol oxidase in the degradation of derivatives of this polymer. Combined data on lignin degradation pathways suggest that basidiomycetous AO is important in secondary reactions during lignin decomposition by wood degrading fungi. With numerous alcoholic substrates, the enzyme is probably engaged in a variety of catalytic reactions leading to the detoxification of compounds produced in lignin degradation processes and their utilization as a carbon source by fungal mycelium.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2023

Observations of ozone, acyl peroxy nitrates, and their precursors during summer 2019 at Carlsbad Caverns National Park, New Mexico

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2020

Tourmaline Reference Materials for the In Situ Analysis of Oxygen and Lithium Isotope Ratio Compositions

Not provided.

Geochemistry & Geophysics↗

DOE OSTI2023

Observations of ozone, acyl peroxy nitrates, and their precursors during summer 2019 at Carlsbad Caverns National Park, New Mexico

Carlsbad Caverns National Park (CAVE) is located in southeastern New Mexico and is adjacent to the Permian Basin, one of the most productive oil and natural gas (O&G) production regions in the United States. Since 2018, ozone (O 3 ) at CAVE has frequently exceeded the 70 ppbv 8-hour National Ambient Air Quality Standard. We examine the influence of regional emissions on O 3 formation using observations of O 3 , nitrogen oxides (NO x = NO + NO 2 ), a suite of volatile organic compounds (VOCs), peroxyacetyl nitrate (PAN), and peroxypropionyl nitrate (PPN). Elevated O 3 and its precursors are observed when the wind is from the southeast, the direction of the Permian Basin. We identify 13 days during the July 25 to September 5, 2019 study period when the maximum daily 8-hour average (MDA8) O 3 exceeded 65 ppbv; MDA8 O 3 exceeded 70 ppbv on 5 of these days. The results of a positive matrix factorization (PMF) analysis are used to identify and attribute source contributions of VOCs and NO x . On days when the winds are from the southeast, there are larger contributions from factors associated with primary O&G emissions; and, on high O 3 days, there is more contribution from factors associated with secondary photochemical processing of O&G emissions. The observed ratio of VOCs to NO x is consistently high throughout the study period, consistent with NO x -limited O 3 production. Finally, all high O 3 days coincide with elevated acyl peroxy nitrate abundances with PPN to PAN ratios > 0.15 ppbv ppbv -1 indicating that anthropogenic VOC precursors, and often alkanes specifically, dominate the photochemistry. Implications: The results above strongly indicate NO x -sensitive photochemistry at Carlsbad Caverns National Park indicating that reductions in NO x emissions should drive reductions in O 3 . However, the NO x -sensitivity is largely driven by emissions of NO x into a VOC-rich environment, and a high PPN:PAN ratio and its relationship to O 3 indicate substantial influence from alkanes in the regional photochemistry. Thus, simultaneous reductions in emissions of NO x and non-methane VOCs from the oil and gas sector should be considered for reducing O 3 at Carlsbad Caverns National Park. Reductions in non-methane VOCs will have the added benefit of reducing formation of other secondary pollutants and air toxics.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2026

Lead Isotope Fingerprinting of Nanoscale Mineral Particles via Single Particle Inductively Coupled Plasma Mass Spectrometry

Determining lead (Pb) isotopic ratios is of broad interest across chemical disciplines for source tracing and age determinations, but the technique is inherently limited when multiple sources of Pb are present in a single sample. Single particle methods offer a solution to directly resolve multiple distinct isotopic ratios within individual samples. In this study, single particle inductively coupled plasma-mass spectrometry (spICP-MS) was performed using time-of-flight (TOF) and multicollector (MC)-based platforms to measure the Pb isotopic composition of individual nanoscale particles. Distinct Pb isotope ratios were measured in particles from four powdered galena samples of different origins (average single-particle 206Pb/207Pb ratios ranging from 0.91 to 1.28) using both the TOF and the MC-based platforms. Differentiation of galena particles in a mixture (liberated grains and those hosted in a silicate matrix) was possible due to detecting their unique multielemental fingerprints. The differing behavior of the two galena samples during digestion was investigated; undigested galena particles trapped within silicate minerals were detected using spICP-MS, which has implications for Pb recovery in bulk-scale isotopic analysis. The multinuclide detection capability of the ICP-TOF-MS instrument allowed for the simultaneous detection of secondary constituent elements within the nanoparticles and the identification of multiple populations of isotopically distinct Pb-bearing particles in a copper ore sample, whereas the increased sensitivity of the MC instrument enabled quantification of 204Pb, allowing differentiation using multiple isotopic ratios. A single particle isotope ratio analysis module was developed within an open-source spICP-TOF-MS data processing platform, enabling its adoption across chemical disciplines.

Goodman, Aaron J. [University of Montreal, Quebec,↗

DOE OSTI2022

Electron Cloud Simulations for the Electron-Ion Collider in Brookhaven National Laboratory

For high-intensity circular accelerators and storage rings, if the secondary electron emission yield (SEY) of the vacuum chamber surfaces is high, an EC (Electron Cloud) could build up with the passage of the circulating beam. The presence of EC can strongly affect the beam quality, such as transverse instabilities, transverse emittance growth, and beam loss. Furthermore, the heat load from EC can exceed the available cryogenic capability. For the RHIC superconducting (SC) arc magnets, to be used for the hadron storage ring of the Electron-Ion Collider (EIC), the dynamic heat load budget is 0.5 W/m to the 4.5 K stainless steel beam pipe. This can limit the maximum beam bunches or intensity of the EIC, hence diminishing the luminosity provided by the EIC. The EC has affected the beam instability and significantly contributed to cryogenic heat load in the Large Hadron Collider (LHC). Positron storage rings for which ECs have been a critical factor in the design and performance include KEKB in Japan and EC buildup remains one of the concerns for future high-intensity accelerators design. EC considerations have driven the SuperKEKB collider design and the positron damping ring for the proposed International Linear Collider (ILC). The LHC luminosity upgrade is contingent on reducing the bunch spacing to 25 ns; at this bunch spacing, severe EC buildup has been observed. The success of the upgrade is likely contingent on limiting EC buildup. To study the EC heat load, we did some EC simulations with PyECLOUD code for the dipole, quadrupole, sextupole magnets, and the warm (drift) section of the EIC hadron storage ring. PyECLOUD is an EC simulation code developed by CERN. The code has been validated and used to study EC in the LHC, SPS, and PS. To eliminate EC buildup, the sources of electrons must be minimized. First, we will reduce the production of electrons due to residual gas ionization by specifying the maximum gas density, which requires a vacuum chamber with low electron-stimulated desorption (ESD) yields and a sufficient (preferably distributed) pumping speed. Second, we should reduce the secondary electrons with a lower secondary electron yield (SEY) material.

43 PARTICLE ACCELERATORS↗

DOE OSTI2024

Sensitivity of Arctic Clouds to Ice Microphysical Processes in the NorESM2 Climate Model

Abstract Ice formation remains one of the most poorly represented microphysical processes in climate models. While primary ice production (PIP) parameterizations are known to have a large influence on the modeled cloud properties, the representation of secondary ice production (SIP) is incomplete and its corresponding impact is therefore largely unquantified. Furthermore, ice aggregation is another important process for the total cloud ice budget, which also remains largely unconstrained. In this study, we examine the impact of PIP, SIP, and ice aggregation on Arctic clouds, using the Norwegian Earth System Model, version 2 (NorESM2). Simulations with both prognostic and diagnostic PIP show that heterogeneous freezing alone cannot reproduce the observed cloud ice content. The implementation of missing SIP mechanisms (collisional breakup, drop shattering, and sublimation breakup) in NorESM2 improves the modeled ice properties, while improvements in liquid content occur only in simulations with prognostic PIP. However, results are sensitive to the description of collisional breakup. This mechanism, which dominates SIP in the examined conditions, is very sensitive to the treatment of the sublimation correction factor, a poorly constrained parameter that is included in the utilized parameterization. Finally, variations in ice aggregation treatment can also significantly impact cloud properties, mainly through their impact on collisional breakup efficiency. Overall, enhancement in ice production through the addition of SIP mechanisms and the reduction in ice aggregation (in line with radar observations of shallow Arctic clouds) result in enhanced cloud cover and decreased TOA radiation biases, compared to satellite measurements, especially during the cold months. Significance Statement Arctic clouds remain a large source of uncertainty in projections of the future climate due to the poor representation of the microphysical processes that govern their life cycle. Ice formation is among the least understood processes. While it is widely recognized that better constraints on primary ice production (PIP) are needed to improve existing parameterizations, we show that secondary ice production (SIP) and ice aggregation can have also a significant impact on ice number concentrations. Constraining ice formation through the addition of missing SIP mechanisms and reducing ice aggregation can improve the representation of the cloud macrophysical properties and enhance total cloud cover in the Arctic region, which in turn contributes to decreased TOA radiation biases in the cold months.

Meteorology & Atmospheric Sciences↗

DOE OSTI2025

On the origins of the continuum radiation of an underwater nanosecond pulsed discharge: an absolute-intensity optical emission spectroscopy study

The plasma properties of an underwater nanosecond pulsed discharge remain not fully understood despite being extensively studied for several decades. In this work, we focus on the continuum radiation generated in such discharges. The discharge is characterized by power measurements as well as by absolute emission spectroscopy. When observed, Stark broadenings of H α , H β and O (777 nm) are employed for electron number densities measurements. The discharge was generated by a 10 ns main voltage pulse followed by multiple secondary pulses, which last up to 4 μs after the primary pulse. It is shown that a peak power of 3.5 MW and energy of 35 mJ is coupled during the main voltage pulse. A quantitative estimation of the different possible continuum radiation sources is performed through analytical calculations. This includes emission (blackbody, free–bound and free–free bremsstrahlung radiations) and absorption (electron–ion and electron–neutral free–free inverse bremsstrahlung) mechanisms. Our results suggest that electron–neutral free–free bremsstrahlung is the principal mechanism responsible for the strong continuum radiation observed experimentally during the primary pulse. We also show that self-absorption through electron–neutral (and electron–ion) inverse bremsstrahlung plays an important role in the main discharge pulse. Further, our results indicate the non-negligible additional contribution of the H 2 continuum during the first reflected pulse which is likely ignited in bubbles generated by the first discharge pulse.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2023

Understanding uncertainties in projections of western North Pacific tropical cyclogenesis

Reliable projections of tropical cyclone (TC) activities in the western North Pacific (WNP) are crucial for climate policy-making in densely-populated coastal Asia. Existing projections, however, exhibit considerable uncertainties with unclear sources. Here, based on future projections by the latest Coupled Model Intercomparison Project Phase 6 climate models, we identify a new and prevailing source of uncertainty arising from different TC identification schemes. Notable differences in projections of detected TCs and empirical genesis potential indices are found to be caused by inconsistent changes in dynamic and thermodynamic environmental factors affecting TC formations. While model uncertainty holds the secondary importance, we show large potential in reducing it through improved model simulations of present-day TC characteristics. Internal variability noticeably impacts near-term projections of the WNP tropical cyclogenesis, while the relative contribution of scenario uncertainty remains small. Our findings provide valuable insights into model development and TC projections, thereby aiding in adaptation decisions.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2026

Computational Modeling of Atmospheric Processes at Texas Southern University

Texas Southern University (TSU) is strengthening its research program in atmospheric chemistry and physics with a climate science emphasis by leveraging partnerships with the U.S. Department of Energy’s Atmospheric Radiation Measurement (ARM) Facility, Brookhaven National Laboratory (BNL), and the Tracking Aerosol Convection Interactions ExpeRiment (TRACER). This RDPP-supported program focuses on secondary organic aerosols (SOAs) and reactive atmospheric species that influence cloud formation, precipitation processes, and radiative forcing. SOAs play a critical role in cloud microphysics and Earth’s energy balance, yet the chemical and physical mechanisms governing SOA–cloud interactions remain a significant source of uncertainty in predictive climate models. Through computational modeling, observational data analysis, and national laboratory collaboration, this program develops a skilled cohort of students trained in atmospheric science, environmental data analysis, and climate-relevant modeling. These research experiences build technical competencies that are transferable to careers in government laboratories, academia, and industry. By engaging students from historically underrepresented communities in high-impact climate research, TSU expands participation in the atmospheric sciences workforce while contributing meaningful scientific insights to DOE-supported ARM research activities. This partnership strengthens national capacity in climate science and supports the development of the next generation of atmospheric researchers.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2022

A 1MHz Oak Ridge AC / DC Converter for UAV Contactless Charger Implementation

In this paper, a 1 MHz single-phase Oak Ridge Converter (ORC) AC/DC wireless power transfer (WPT) system is introduced for unmanned air vehicle (UAV) charging applications. The proposed advanced solution eliminates the design, weight, volume, and the cost of the power factor correcting (PFC) front-end rectifier compared to the conventional practices. Additionally, grid power quality requirements can be achieved with the presented innovative idea. With this method, single stage WPT primary side uses the hybrid grid frequency and high frequency (60 Hz and 1 MHZ) from ac source through the coupler coils and to UAV battery with GaN FETs. Experimental results of the single-phase system is presented to confirm the mathematical analyses with the source voltage of 110 VAC, RMS and output voltage of 40 VDC at 1 kW power with 6 inches air gap between couplers. The primary coupler consists of a ferrite-backed single-turn coil with a radius of 1.5 ft, and the secondary coupler is made with an air-core single-turn coil with radius of 1.2 ft. The system overall ac to dc efficiency is measured 77 % acquiring 0.99 power factor (PF) and 3.3 % current total harmonic distortion (THD) at 1 kW power.

Asa, Erdem↗

DOE OSTI2025

Hyperselective carbon membranes for precise high-temperature H 2 and CO 2 separation

More than 90% of the world’s hydrogen (H 2 ) is produced from fossil fuel sources, which requires energy-intensive separation and purification to produce high-purity H 2 fuel and to capture the carbon dioxide (CO 2 ) by-product. While membranes can decarbonize H 2 /CO 2 separation, their moderate H 2 /CO 2 selectivity requires secondary H 2 purification by pressure swing adsorption. Here, we report hyperselective carbon molecular sieve hollow fiber membranes showing H 2 /CO 2 selectivity exceeding 7000 under mixture permeation at 150°C, which is almost 30 times higher than the most selective nonmetallic membrane reported in the literature. The membrane is able to maintain an ultrahigh H 2 /CO 2 selectivity over 1400 under mixture permeation at 400°C. Pore structure characterization suggests that highly refined ultramicropores are responsible for effectively discriminating the closely sized H 2 and CO 2 molecules in the hyperselective carbon molecular sieve membrane. Modeling shows that the unprecedented H 2 /CO 2 selectivity will potentially allow one-step enrichment of fuel-grade H 2 from shifted syngas for decarbonized H 2 production.

Science & Technology - Other Topics↗