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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 919 records · Page 51
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Realizing the scientific program with polarized ion beams at the future BNL Electron Ion Collider

Polarized ion beams at the Electron Ion Collider (EIC) are essential to address some of the most important open questions at the twenty-first century frontiers of understanding of the fundamental structure of matter. Here, in this work, we summarize the science case and identify polarized 2 H, 3 He, 6 Li, and 7 Li ion beams as critical technology that will enable experiments which address the most important science. Furthermore, we discuss the required ion polarimetry and spin manipulation at the EIC. The current EIC accelerator design is presented. We identify a significant research and development effort across national and international laboratories and universities that is required over about a decade to realize the polarized ion beams and estimate (based on previous experience) that it will require about 20 full-time equivalent (FTE) over 10 years (or a total of about 200 FTE-years) of personnel, including graduate students, postdoctoral researchers, technicians, and engineers. Attracting, educating, and training a new generation of physicists in experimental spin techniques will be essential for the successful realization. Artificial intelligence and machine learning are seen as having significant potential for both acceleration of research and development and amplification of discovery in the optimal realization of this unique quantum technology on a cutting-edge collider. The research and development effort is synergistic with research in atomic physics and fusion energy science.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

Determining the 9 $\mathrm{Be}$($n, γ$) 10 $\mathrm{Be}$ integral cross section at fission neutron energies

The 9 B neutron capture cross section has significant implications for Be materials in the nuclear industry as well as the α process in stellar nucleosynthesis. While the cross section is well constrained at thermal neutron energies, there is a lack of experimental data at higher neutron energies, and the evaluated nuclear data libraries can differ by up to two orders of magnitude. We calculate the 9 Be(n, γ) 10 Be integral cross section at fission neutron energies in an effort to resolve disagreements amongst the nuclear data libraries. Foil irradiation experiments were performed using the Flattop critical assembly at the National Criticality Experiments Research Center with either the highly enriched U or Pu cores, with target foil stacks placed at multiple locations to exploit different neutron energy profiles. Accelerator mass spectrometry was used to measure the 10 Be/ 9 Be ratio in irradiated Be foils, while all other activation products were quantified through gamma spectrometry. The experiments were simulated using the Monte Carlo N-Particle radiation transport code and combined with experimental results to determine the total neutron fluence, while the staysl-pnnl suite and fispact-ii code were used to validate the model and assess the systematic uncertainty. The new 9 Be(n, γ) 10 Be integral cross sections calculated in this work are 26.5 ± 2.2µb at 0.59 ± 0.07 MeV, 24 ± 3 µb at 0.98 ± 0.14 MeV, 21.7 ± 1.3 µb at 1.26 ± 0.11 MeV, 21.8 ± 1.4 µb at 1.32 ± 0.11 MeV, and 18.6 ± 1.1 µb at 1.46 ± 0.13 MeV. These results do not agree with integral cross sections from any of the nuclear data library evaluations. Discrepancies between the new integral cross sections reported here and the nuclear data libraries suggest a more complex cross-section structure in the MeV range which allows for more resonance contributions, and more work is needed to further constrain the evaluated cross sections.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2022

Modeling of the Optical Stochastic Cooling at the IOTA Storage Ring Using ELEGANT

In support of the Optical Stochastic Cooling (OSC) experiment at IOTA, we implemented a high-fidelity model of OSC in ELEGANT. The element is generalizable to any OSC experiment and captures three main behaviors; (i) the longitudinal time of flight OSC, (ii) the effects between the transverse motion of particles in the beam and the transverse distribution of undulator radiation, and (iii) the incoherent contributions of neighboring particles. Together these produce a highly accurate model of OSC and were benchmarked using the results from the IOTA OSC experiment.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

Extension of Virtual Test Bed Advanced Modeling and Simulation Capabilities for Fusion Energy

The National Reactor Innovation Center (NRIC) was established to accelerate the deployment of novel reactor concepts. This is achieved by providing physical and virtual spaces for building and testing reactor experiments. The Virtual Test Bed (VTB) represents the virtual counterpart to the physical test beds. It is a collaboration with the Department of Energy’s (DOE) Nuclear Energy Advanced Modeling and Simulation (NEAMS) program with the mission to accelerate the deployment of advanced reactors by facilitating the adoption of advanced modeling and simulation (M&S) tools developed by the DOE. This mission has been carried out by the VTB since 2020 by hosting and featuring dozens of advanced fission nuclear reactor models developed by national laboratories and academia. The charter of the NRIC’s definition of advanced reactors also includes fusion nuclear reactors. As the tools developed by the NEAMS program are increasingly used for modeling fusion energy devices, there is an increasing need to host fusion reactor models on the VTB repository. The VTB will be extended in 2024 to support fusion energy modeling and simulation.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2026

Recent developments and operation of polarized photocathodes at Jefferson Lab

Spin-polarized electron sources are critical to a wide range of accelerator-based applications for nuclear and particle physics. At Thomas Jefferson National Accelerator Facility, they play a central role in delivering high-quality polarized beams for precision nuclear physics experiments and next-generation parity-violation measurements, where stringent control of systematic uncertainties is essential. These sources are also expected to be key components of other initiatives, including the Electron-Ion Collider and the potential future positron capabilities at Jefferson Lab. In this talk, I will present ongoing research and development efforts at Jefferson Lab focused on the design, fabrication and optimization of spin-polarized photocathodes. This includes growth using molecular beam epitaxy (MBE) or metal-organic chemical vapor deposition (MOCVD), along with detailed characterization of their performance metrics, such as quantum efficiency (QE), electron spin polarization and QE anisotropy, all of which are increasingly important metrics for polarized electron sources at Jefferson Lab and the Electron-Ion Collider. Strategies to mitigate QE anisotropy, which is critical for reducing helicity-correlated beam asymmetries in precision experiments such as MOLLER will be highlighted. Finally, I will present recent efforts aimed at improving the operational lifetime of spin-polarized photocathodes in injector environments, particularly under high-voltage conditions in DC electron guns. These developments are essential for enabling reliable, high-performance operation of polarized sources for current and future accelerator programs.

Kachwala, Alimohammed [Thomas Jefferson National A↗
DOE OSTI2021

Cathode to Target Simulations for Scorpius: I. Simulation Codes and Models

The new Scorpius linear induction electron accelerator is under development for multi-pulse flash radiography of large, explosively-driven hydrodynamic experiments. Beam physics from the cathode to the target was examined with computer simulations, including envelope, ray-trace, and particle-in cell (PIC) codes. Beam instabilities investigated included beam breakup (BBU), image displacement, diocotron, parametric envelope, ion hose, and the resistive wall instability. Beam corkscrew motion and emittance growth from beam mismatch were also studied. The results of these simulations is documented in a series of reports. In this report the computer codes and physical models used for these simulations are described. The conclusion of this study is that Scorpius will produce and accelerate a beam with radiographic quality equivalent to the present accelerators at Los Alamos National Laboratory if the same engineering standards and construction details are upheld.

43 PARTICLE ACCELERATORS↗
DOE OSTI2025

Mechanistic Multiscale Uncertainty Propagation in Support of Accelerated Fuel Qualification

Taking a nuclear fuel concept through the research, development, and qualification stages has historically taken on the order of 20 to 25 years because of extensive irradiation tests required for a variety of conditions. The concept of accelerated fuel qualification (AFQ) has been proposed to increase the innovation pace for nuclear fuels. The goal of AFQ is not to replace the traditional qualification approach but rather to reduce the total number of experiments required to ensure approval from the regulatory authority. Of the many AFQ approaches being explored, advanced modeling—and, in particular, mechanistic modeling—is in a uniquely cross-cutting position to reduce the number of required integral tests through the inclusion of separate-effects testing, while helping to extrapolate reactor performance during rare events. We make the case that propagation of uncertainty through various computational length scales helps contextualize mechanistic modeling. We will utilize UO 2 fission gas diffusion predictions from the atomistically informed cluster dynamics code Centipede to inform fuel performance rodlet simulations using the BISON finite element code as the metric for showing how multiscale mechanistic uncertainty quantification can help reduce uncertainty in fuel performance. In conclusion, by quantifying uncertainty and its reduction through multiscale modeling, the qualification process may be accelerated through the reduction of costly irradiation experiments.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2026

Optical stochastic cooling at Fermilab’s IOTA ring

Stochastic cooling (SC) constitutes one of the greatest conceptual and technological achievements in particle beam cooling. Numerous SC systems have been built in the microwave regime and used to extend the science reach of accelerator facilities worldwide. The ability to sense and correct the particle ensemble using high-bandwidth feedback systems is at the core of the concept. Here, we describe the first realization of SC at optical frequencies and bandwidths. The demonstration was recently carried out at Fermilab’s integrable optics test accelerator (IOTA) storage ring using the transit-time method of optical stochastic cooling (OSC) and achieved an integrated system bandwidth of approximately 20 THz, which is more than 2000 times that of conventional SC systems. This demonstration establishes the foundation for more advanced OSC experiments with high-gain amplification, currently underway at Fermilab, and the eventual application of OSC to colliders and other accelerator facilities.

Jarvis, Jonathan D. [Fermilab]↗
DOE OSTI2020

Accelerating Deployment of Distributed Photovoltaics in Partner Countries

There is a significant opportunity to help developing countries quickly augment DPV programs, and a wealth of international experience and expertise to draw upon to do so. USAID has launched a multi-year program to assist countries across the DPV spectrum. The National Renewable Energy Laboratory (NREL) is supporting USAID (and drawing on Lawrence Berkeley National Laboratory and others) in developing and implementing pilot projects in selected USAID partner countries, collaborating with these countries to accelerate DPV market development.

distributed photovoltaics↗
DOE OSTI2026

Dynamic Nanoscale Spatial Heterogeneity in a Perovskite-to-Brownmillerite Topotactic Phase Transformation

Phase transitions are omnipresent in modern condensed matter physics and its applications. In solids, first-order phase transformations typically occur by nucleation and growth under nonequilibrium conditions. Under constant external conditions, e.g., constant annealing temperature and pressure, the nucleation and growth dynamics are often thought of as spatially and temporally independent. Here, in situ Bragg X-ray photon correlation spectroscopy (XPCS) reveals nanoscale spatial and dynamical heterogeneity in the perovskite-to-brownmillerite topotactic phase transformation in La 0.7 Sr 0.3 CoO 3 thin films annealed under constant reducing conditions over a time span of multiple hours. Specifically, a time scale associated with domain growth remains stable, with a corresponding domain wall speed of v d = 6 ± 0.5 × 10 –4 nm/s (2 ± 0.2 nm/h), while a slower time scale, associated with temperature-driven depinning of domains, leads to accelerating dynamics with time scales following an aging power law with exponent −2.2 ± 0.5. This experiment demonstrates that Bragg XPCS is a powerful tool to study nanoscale dynamics in structural phase transformations, with the ability to extract quantitative average values related to nanodomain motion in situ. Furthermore, the results are relevant for phase engineering of phase-change devices, as they show that nanoscale dynamics, linked to domain and domain-wall motion, can continuously evolve and speed up with time, even hours after the initiation of the phase transformation, with potential repercussions on electrical performance.

X-ray photon correlation spectroscopy↗
DOE OSTI2023

Cathode Side-emission Mitigation for Linear Induction Accelerators

Linear induction accelerators (LIAs) are one of the main technologies used in creating flash x-rays used for diagnosing hydrodynamic experiments. The quality of the data produced in these experiments is dependent on the dose of x-rays generated via bremsstrahlung radiation. There are several electron beam quantities that effect the amount of dose extracted from the bremsstrahlung radiation, such as beam instabilities, corkscrew motion, and beam emittance. Injector design is key in delivering well-behaved electron beams to the accelerator, and design choices include components such as anode-cathode (AK) gap dimensions based on required voltage and current, shroud shaping, and cathode type and composition. Thermionic cathodes have shown reliable performance in electron emission, however, if enough of the cathode side is subject to high-enough electric field values, electrons can be emitted. This issue is more likely to happen when the cathode is treated with materials that have lower work functions, which is common for cathodes used in LIAs. These extra electrons can work their way through the rest of the beam, inducing high non-linearities in phase space which can increase the emittance of this beam. In this paper we outline conducted trade-space studies where we examined different shaping parameters of the cathode shroud design to decrease the effect side electrons may have on the beam emittance. Particle trajectories are determined by electric potential contours across the face of the cathode shroud component, and so we hypothesize that the proper shaping of the cathode-shroud interface can tune the electric field to mitigate the effect of side electrons. Electron beam transport is simulated down the length of the injector and the beam quality is diagnosed by studying the emittance as a function of position. Acceptable emittance increase is recorded and noted to meet radiographic requirements.

42 ENGINEERING↗
DOE OSTI2022

Validation of material models for puncture of 7075-T651 aluminum plate

Plate puncture simulations are challenging computational tasks that require advanced material models including high strain rate and thermal-mechanical effects on both deformation and failure, plus finite element techniques capable of representing large deformations and material failure. The focus of this work is on the material issues, which require large sets of experiments, flexible material models and challenging calibration procedures. In this study, we consider the puncture of 12.7 mm thick, 7075-T651 aluminum alloy plates by a cylindrical punch with a hemispherical nose and diameter of 12.7 mm. The plasticity and ductile failure models were isotropic with calibration data obtained from uniaxial tension tests at different temperatures and strain rates plus quasi-static notched tension tests and shear-dominated tests described here. Sixteen puncture experiments were conducted to identify the threshold penetration energy, mode of puncture and punch acceleration during impact, The punch was mounted on a 139 kg mass and dropped on the plates with different impact speeds. Since the mass was the same in all tests, the quantity of interest was the impact speed. The axis and velocity of the punch were perpendicular to the plate surface. The mean threshold punch speed was 3.05 m/s, and the mode of failure was plugging by thermal-mechanical shear banding accompanied by scabbing fragments. Application of the material models in simulations of the tests yielded accurate estimates of the threshold puncture speed and of the mode of failure. Time histories of the punch acceleration compared well between simulation and test. Remarkably, the success of the simulations occurred in spite of even the smallest element used being larger than the width of the shear bands.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Chromium-doped uranium dioxide fuels: A review

UO 2 doped with parts per million CR 2 O 3 powder is considered a potential near term accident tolerant fuel candidate. Here, the results of decades of industry and academic research into Cr-doped UO 2 are analyzed and their shortcomings are critiqued. Focusing on the incorporation mechanisms of Cr into the fuel matrix, we explore a mechanistic understanding of the characteristic properties of Cr-doped UO 2 , notably, enhanced fission gas retention attributed to enlarged grain sizes following sintering, along with marginal improvements in the thermophysical properties. The findings of recent X-ray Adsorption Near Edge Spectroscopy studies were compared and put into conversation with historic data regarding the incorporation of Cr in UO 2 . On the basis of defect mechanisms, the case is made for the substitutional incorporation of Cr governing the lattice solubility but not the enhanced U diffusivity. Instead, Cr/CR 2 O 3 redox chemistry in a well-defined oxygen potential explains the differences in the U diffusivity and O/M ratio. The primary mechanism of doping enhanced grain growth is found to be liquid assisted sintering due to a CRO (1) eutectic phase at the grain boundaries. The role of inhomogeneities in Cr concentration in UO 2 at various length scales across the materials microstructure is highlighted and connected to promising experimental and modeling work to fill in the gaps in the current understanding of Cr-doped UO 2 . The review considers both the open scientific questions and engineering applications to illustrate the deep connections between the practice and theory in the design of accident tolerant nuclear fuels. In conclusion, the review ends with an outline of future works that combine meticulous irradiation studies and high resolution experiments with next generation modeling and simulations techniques empowered by machine learning advances to accelerate the fabrication and adoption of Cr-doped UO 2 light water reactors.

Cleveland, Mack Wesley [Massachusetts Inst. of Tec↗
DOE OSTI2024

A critical review of irradiation-induced changes in reactor pressure vessel steels

A large body of work has been conducted to investigate the embrittlement and degradation of reactor pressure vessel (RPV) steels. This includes experiments on alloys with different compositions, performed in research and test reactors and ion accelerators that span various temperatures, fluxes, and fluences. In this paper, we perform a critical review of the published experimental data and compile experimentally reported values for dislocation loop size/density, precipitate size/density and yield stress into an easily downloadable format that can be used by both experimentalists and modelers. This thorough experimental review is complemented by a brief review of simulation efforts at atomistic and mesoscopic length scales. Finally, this paper highlights key aspects of the behavior of RPV steels under irradiation, identifies gaps or discrepancies in current understanding, and identifies priority future research directions.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Tailoring MoS 2 for Small-Molecule Electroreduction: The Role of Metal Doping and Heterostructures

The electrification of chemical transformations central to sustainable fuel production and waste valorization, such as overall water splitting (OWS), hydrogen evolution reaction (HER), and electrochemical reduction of CO 2 (CO 2 R), presents a powerful opportunity to advance carbon-neutral energy technologies. Transition metal dichalcogenides (TMDs), particularly MoS 2 , have emerged as promising electrocatalyst candidates, owing to their abundance, tunable active sites, and defect-rich structures. This review highlights recent progress in leveraging metal doping and heterostructure engineering of MoS 2 to enhance the electrocatalytic activity and selectivity. By compiling insights from experimental studies and density functional theory (DFT) predictions, we examine how defect creation, electronic structure modification, and interface design contribute to improved charge transport and catalytic efficiency. Particular emphasis is placed on rational design principles, synthetic strategies, and operando characterization methods that provide a pathway to understanding and optimizing MoS 2 -based materials. We also discuss the challenges of stability, mechanistic ambiguity, and scaling while outlining opportunities to bridge theory and experiment. Collectively, this review underscores how defect and heterostructure engineering of MoS 2 can accelerate the development of efficient, sustainable electrocatalysts for both fuel generation and waste-to-value generation.

CO2 reduction↗
DOE OSTI2025

Data-driven design of electrolyte additives supporting high-performance 5 V LiNi 0.5 Mn 1.5 O 4 positive electrodes

LiNi 0.5 Mn 1.5 O 4 (LNMO) is a high-capacity spinel-structured material with an average lithiation/de-lithiation potential at ca. 4.6–4.7 V vs Li + /Li, far exceeding the stability limits of electrolytes. An efficient way to enable LNMO in lithium-ion batteries is to reformulate an electrolyte composition that stabilizes both graphitic (Gr) negative electrode with solid-electrolyte-interphase and LNMO with cathode-electrolyte-interphase. In this study, we select and test a diverse collection of 28 single and dual additives for the Gr||LNMO battery system. Subsequently, we train machine learning models on this dataset and employ the trained models to suggest 6 binary compositions out of 125, based on predicted final area-specific-impedance, impedance rise, and final specific-capacity. Such machine learning-generated new additives outperform the initial dataset. This finding not only underscores the efficacy of machine learning in identifying materials in a highly complicated application space but also showcases an accelerated material discovery workflow that directly integrates data-driven methods with battery testing experiments.

batteries↗
DOE OSTI2025

Direct identification of Ac and No molecules with an atom-at-a-time technique

The periodic table provides an intuitive framework for understanding chemical properties. However, its traditional patterns may break down for the heaviest elements occupying the bottom of the chart. Here, the large nuclei of actinides (Z > 88) and superheavy elements (Z ≥ 104) give rise to relativistic effects that are expected to substantially alter their chemical behaviours, potentially indicating that we have reached the end of a predictive periodic table. Relativistic effects have already been cited for the unusual chemistry of the actinides compared with those of their lanthanide counterparts. Unfortunately, it is difficult to understand the full impact of relativistic effects, as research on the later actinides and superheavy elements is scarce. Beyond fermium (Z = 100), elements need to be produced and studied one atom at a time, using accelerated ion beams and state-of-the-art experimental approaches. So far, no experiments have been capable of directly identifying produced molecular species. Here ions of actinium (Ac, Z = 89) and nobelium (No, Z = 102) were synthesized through nuclear reactions at the 88-Inch Cyclotron facility at Lawrence Berkeley National Laboratory and then exposed to trace amounts of H 2 O and N 2 . The produced molecular species were directly identified by measuring their mass-to-charge ratios using FIONA (For the Identification Of Nuclide A). These results mark the first, to our knowledge, direct identification of heavy-element molecular species using an atom-at-a-time technique and highlight the importance of such identifications in future superheavy-element chemistry experiments to deepen understanding of their chemical properties.

Pore, Jennifer L. [Lawrence Berkeley National Labo↗
DOE OSTI2023

Experimental observation of a field-aligned ion beam produced by magnetic reconnection of two flux ropes

An ion beam field-aligned to the background guide field ($B$ 0 = $330$ G) was observed in a reconnection experiment on the Large Plasma Device and, to the authors' knowledge, is the first experimental observation of its kind. Two kink-unstable flux ropes ( L = 11 m, d = 7.6 cm) were made to collide, which allows magnetic reconnection to occur. Sub-Alfvénic ion beams with energies of up to 15 eV were then observed from measurements of the local ion energy distribution function. The beam ions do not appear to be heated. Further, they were correlated with the collision of the ropes and appear to be energized by magnetic reconnection. The results and interpretation of the measurements are supported by three-dimensional gyrokinetic particle simulations of the merging flux ropes and electric field measurements from previous experiments [W. Gekelman et al. , Astrophys. J. 853, 33 (2018)]. The mechanism behind the acceleration appears to be non-local.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗