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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Sputtering of uranium

Results are presented for an experimental study of the sputtering of U-235 atoms from foil targets by hydrogen, helium, and argon ions, which was performed by observing tracks produced in mica by fission fragments following thermal-neutron-induced fission. The technique used allowed measurements of uranium sputtering yields of less than 0.0001 atom/ion as well as yields involving the removal of less than 0.01 monolayer of the uranium target surface. The results reported include measurements of the sputtering yields for 40-120-keV protons, 40-120-keV He-4(+) ions, and 40- and 80-keV Ar-40(+) ions, the mass distribution of chunks emitted during sputtering by the protons and 80-keV Ar-40(+) ions, the total chunk yield during He-4(+) sputtering, and some limited data on molecular sputtering by H2(+) and H3(+). The angular distribution of the sputtered uranium is discussed, and the yields obtained are compared with the predictions of collision cascade theory.

Gregg, R.↗
DOE OSTI2024

Perovskite/Perovskite Tandem Photoelectrodes for Low-Cost Unassisted Photoelectrochemical Water Splitting

In this project, we aim to address the challenges of achieving efficient and cost-effective unassisted photoelectrochemical water splitting using perovskite/perovskite tandem photoelectrodes. We utilized the following unique approaches to advance our innovation. (1) We developed stable and efficient low-E g (1.2 – 1.4 eV) perovskites as the bottom electrodes. We demonstrated approaches to improve the photovoltaic performance and photothermal stability of low-E g Sn-Pb iodide perovskite solar cells. (2) We developed a low-temperature synthesis route to fabricate wide-E g (>1.8 eV) perovskite top electrodes. By combining theoretical and experimental investigation, we found methods to reduce the formation of defects and dislocations in the wide-E g mixed halide perovskites and suppress halide segregation. (3) We developed a robust metal oxide-based interconnecting layer to integrate two perovskite layers into tandem photoelectrodes. Our monolithically integrated tandem devices feature a high V OC of more than 2 V and a high J SC of more than 15 mA/cm 2 . We showed the new design of the tandem photoelectrodes that is critical to the stable operation of tandem photoelectrodes for unassisted PV/PEC water splitting. (4) We demonstrated a water-impermeable barrier of carbon paste/epoxy/metal foil composite, which can prevent photocorrosion and water ingress of perovskite active layers. This surface protection enabled the operation of perovskite photoelectrodes in water and significantly enhanced the long-term stability of our tandem devices. (5) We conducted standardized PEC characterization in collaboration with NREL and reported accurate determination of solar-to-hydrogen conversion efficiencies of perovskite/perovskite tandem photoelectrodes. At the end of the project, we demonstrated perovskite/perovskite tandem photoelectrodes with STH efficiencies of up to 18% and less than 20% efficiency loss after continuous operation for more than 500 hours in water. Our results demonstrate the potential to develop a low-cost, durable, and efficient water-splitting system that meets the DOE 2026 and 2031 cost targets for hydrogen production.

08 HYDROGEN↗
DOE OSTI2025

Achieving the hydrogen shot: Interrogating ionomer interfaces

The aim of this study is to enable the hydrogen economy and decarbonize various sectors in our environment that requires less expensive and more durable water electrolyzers, which can meet the Hydrogen-Shot target. The key is to improve the ionomer interfaces in low-temperature water electrolyzers as rapidly as possible, but to do so, it requires a systematic and holistic campaign combining both experiments and theory. In this perspective, we discuss the issues of electrolyzers and needs for translational science. We then present the approach that the Energy EarthShot Research Center: Center for Ionomer-based Water Electrolysis is taking in hopes of inspiring the community with this approach that can be leveraged to multiple problems and technologies.Graphical abstractHighlightsOne way to achieve the Hydrogen-Shot goal of low-cost, clean hydrogen, is advancing research and development on the interfaces of water electrolyzers for both performance and lifetime. The Center for Ionomer-based Water Electrolysis is exploring new techniques and strategies to not only interrogate interfacial phenomena in water electrolyzers to increase efficiency and durability, but also a new paradigm related to synergistic, cojoined experimental and theoretical research.DiscussionCatalyst\ionomer interfaces are complex and not fully understood, but through investigating different interfaces and utilizing digital and physical twins, we can elucidate key mechanisms and understanding.Understanding the dynamic double layer in electrochemical systems that use solid electrolytes is crucial to identifying and mitigating the controlling phenomena to enable increased performance and durability at the technology level.Studying the time and length scales of interfacial changes can be a powerful tool to understand reaction mechanisms and changes in the electrolyzer performance and durability.

Fornaciari, Julie C↗
DOE OSTI2021

Technoeconomic and Life Cycle Analysis of Synthetic Methanol Production from Hydrogen and Industrial Byproduct CO 2

Here CO 2 capture and utilization provides an alternative pathway for low-carbon hydrocarbon production. Given the ample supply of high-purity CO 2 emitted from ethanol and ammonia plants, this study conducted technoeconomic analysis and environmental life cycle analysis of several systems: integrated methanol-ethanol coproduction, integrated methanol-ammonia coproduction, and stand-alone methanol production systems, using CO 2 feedstock from ethanol plants, ammonia plants, and general market CO 2 supply. The cradle-to-grave greenhouse gas emissions of methanol produced from the stand-alone methanol, integrated methanol-ethanol, and integrated methanol-ammonia systems are 13.6, 37.9, and 84.6 g CO 2 -equiv/MJ, respectively, compared to 91.5 g CO 2 -equiv/MJ of conventional methanol produced from natural gas. The minimum fuel selling price (MFSP) of methanol ($\$0.61-0.64$/kg) is 61-68% higher than the average market methanol price of $\$0.38$/kg, when using a Department of Energy target renewable hydrogen production price of $\$2.0$/kg. The methanol price increases to $\$1.24-1.28$/kg when the hydrogen price is $\$5.0$/kg. Without CO 2 abatement credits, the H 2 price needs to be within $\$0.77-0.95$/kg for the MFSP of methanol to equal the average methanol market price. With a CO 2 credit of $\$35$/MT according to tax credit per metric ton of CO 2 captured and used, the methanol price is reduced to $\$0.56-0.59$/kg.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2026

Quantifying Sources of Long-Term Voltage Decay for Rutile Iridium Oxide Anodes in Proton Exchange Membrane Water Electrolysis

To achieve aggressive hydrogen cost targets for proton exchange membrane water electrolysis (PEMWE), it is necessary to develop catalyst systems that reduce precious metal loadings while maintaining performance over extended operation. While amorphous iridium (Ir) -based catalysts exhibit high initial activity, their long-term stability remains a key limitation. In this study, the behavior of a rutile IrO2 catalyst is investigated over 4000 h of durability testing and compared to past efforts evaluating a more amorphous material. This study finds that rutile IrO2 results in a smaller decay rate (4.9 ..mu..V h-1) than an amorphous catalyst (28 ..mu..V h-1); additionally, the rutile IrO2 results in a smaller degree of Ir migration (20% to the membrane and cathode) than an amorphous catalyst (35%). This research emphasizes rutile IrO2 as a promising avenue for the development of durable, low-iridium anodes that can meet lifetime and cost targets for next-generation electrolyzer systems.

08 HYDROGEN↗
DOE OSTI2021

The PRad windowless gas flow target

In this work, we report on a windowless, high-density, gas flow target at Jefferson Lab that was used to measure $r_p$, the root-mean-square charge radius of the proton. To our knowledge, this is the first such system used in a fixed-target experiment at a (non-storage ring) electron accelerator. The target achieved its design goal of an areal density of 2$\times$10$^{18}$ atoms/cm$^2$, with the gas uniformly distributed over the 4 cm length of the cell and less than 1% residual gas outside the cell. This design eliminated scattering from the end caps of the target cell, a problem endemic to previous measurements of the proton charge radius in electron scattering experiments, and permitted a precise, model-independent extraction of $r_p$ by reaching unprecedentedly low values of $Q^2$, the square of the electron's transfer of four-momentum to the proton.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2025

Hydrogen production from high-volume organic construction and demolition wastes

The Energy & Environmental Research Center (EERC) has partnered with Simonpietri Enterprises, LLC (SEL) with the objective of developing an integrated waste preparation, gasification, and syngas cleanup process capable of using a high-volume, negative-value, highly contaminated feedstock consisting of construction and demolition (C&D) waste to economically produce 99+% pure hydrogen. The target is to achieve $\$$1/kg H2 at a modular scale ranging from 5- to 50-MWe-equivalent size by testing the gasification of organic C&D debris containing treated waste lumber and construction materials, permanently sequestering contaminants into the ash. C&D debris waste is one the largest-volume waste streams in the United States; is already aggregated and available across the country, lending itself to hub operations; and has fewer alternatives for energy conversion than are available for coal, biomass, and municipal solid waste because of contamination from treated lumber and other construction materials.

08 HYDROGEN↗
DOE OSTI2025

Quantifying Sources of Voltage Decay in Long-Term Durability Testing for PEM Water Electrolysis

Meeting a competitive 1$/kg hydrogen cost target for polymer electrolyte membrane water electrolysis (PEMWE) will require advances to significantly reduce capital costs and precious metal catalyst usage, while simultaneously enabling 40,000–80,000 h stack lifetimes under dynamic use conditions. Minimizing cell voltage decay rates is therefore a key goal for PEMWE, although the fundamental processes governing voltage decay are not yet well understood. Here we present a quantitative approach to analyze the contributions to voltage decay in long-term PEMWE testing using polarization curves, impedance spectroscopy, and post-mortem electron microscopy. We apply this approach to analyze a 28 μV h −1 decay rate observed in a 4000 h durability test of a cell using 0.5 mg cm −2 total PGM catalyst loading (0.4 mg Ir cm −2 anode, 0.1 mg Pt cm −2 cathode) and 3 A cm −2 current density. We also analyze a comparative series of 1000 h tests under different conditions. These results provide valuable insights into anode catalyst degradation processes, as well as transferrable methodology for PEMWE durability research.

08 HYDROGEN↗
DOE OSTI2023

Materials Design Directions for Solar Thermochemical Water Splitting

The sustainable, economical production of molecular hydrogen is a crucial component of a net zero-greenhouse-gas-emissions future. Solar thermochemical water splitting (STWS) offers a renewable route to hydrogen with the potential to help decarbonize several industries, including transportation, manufacturing, mining, metals processing, and electricity generation, as well as provide sustainable hydrogen as a chemical feedstock. STWS uses high temperatures generated from concentrated sunlight or other sustainable means for high-temperature heat to produce hydrogen and oxygen from steam. For example, in its simplest form of a two-step thermochemical cycle, a redox-active metal oxide is heated to ≈1700-2000 K, driving off molecular oxygen while producing oxygen vacancies in the material. The reduced metal oxide then cools (ideally with the extracted heat recuperated for re-use) and, in a separate step, comes into contact with steam, which reacts with oxygen vacancies to produce molecular hydrogen while recovering the original state of the metal oxide. Despite its promising use of the entire solar spectrum to split water thermochemically, the current estimated cost of hydrogen produced via STWS is ≈4-6× the U.S. Department of Energy (DOE) Hydrogen Shot target value of $1/kg. One contributing approach to bridging this cost gap is the design of new materials with improved thermodynamic properties to enable higher efficiencies. The state-of-the-art (SOA) redox-active metal oxide for STWS is ceria (CeO 2 ), due to its close to optimal, although too high, oxygen vacancy formation enthalpy and large configurational and electronic entropy of reduction. However, ceria requires high operating temperatures and its efficiency is insufficient. Therefore, efforts to increase the efficiency of STWS cycles have focused on further optimizing oxygen vacancy formation enthalpies and augmenting the reduction entropy via substitution or doping and materials discovery schemes. Examples of the latter include the perovskites BaCe 0.25 Mn 0.75 O 3 and (Ca,Ce)(Ti,Mn)O 3 . These efforts and others have revealed intuitive chemical principles for the efficient and systematic design of more effective materials, such as the strong correlation between the enthalpies of crystal bond dissociation and solid-state cation reduction with the enthalpy of oxygen vacancy formation, as well as configurational entropy augmentation via the coexistence of two or more redox-active cation sublattices. The purpose of this chapter is to prepare the reader with an up-to-date account of STWS redox-active materials, both the SOA and promising newcomers, as well as to provide chemically intuitive strategies for improving their cycle efficiencies through materials design – in conjunction with ongoing efforts in reactor engineering and gas separations – to reach the cost points for commercial viability. First, we will introduce the thermodynamics of STWS using a two-step, metal-oxide, thermochemical cycle with economics in mind. We also will compare the pros and cons of processes that do or do not involve phase changes. Second, we will describe the qualities that make ceria the SOA STWS redox-active material, as well as its limitations. Third, we will survey some of the most promising candidates to date in the search for materials to supplant ceria, emphasizing the post-ternary, metal-oxide-perovskite alloys. Lastly, we will enumerate and discuss the following materials design directions for STWS redox-active materials: crystal reduction potentials as a proxy for oxygen vacancy formation enthalpies, engineering the electronic and configurational entropy of reduction via f-shells and simultaneous redox, and vetting materials stability via temperature-dependent phase diagrams and melting-point prediction.

08 HYDROGEN↗
DOE OSTI2022

Off-harmonic optical probing of high intensity laser plasma expansion dynamics in solid density hydrogen jets

Due to the non-linear nature of relativistic laser induced plasma processes, the development of laser-plasma accelerators requires precise numerical modeling. Especially high intensity laser-solid interactions are sensitive to the temporal laser rising edge and the predictive capability of simulations suffers from incomplete information on the plasma state at the onset of the relativistic interaction. Experimental diagnostics utilizing ultra-fast optical backlighters can help to ease this challenge by providing temporally resolved inside into the plasma density evolution. We present the successful implementation of an off-harmonic optical probe laser setup to investigate the interaction of a high-intensity laser at 5.4 x 10 21 W/cm 2 peak intensity with a solid-density cylindrical cryogenic hydrogen jet target of 5μm diameter as a target test bed. The temporal synchronization of pump and probe laser, spectral filtering and spectrally resolved data of the parasitic plasma self-emission are discussed. The probing technique mitigates detector saturation by self-emission and allowed to record a temporal scan of shadowgraphy data revealing details of the target ionization and expansion dynamics that were so far not accessible for the given laser intensity. Plasma expansion speeds of up to (2.3 ± 0.4)x 10 7 m/s followed by full target transparency at 1.4ps after the high intensity laser peak are observed. A three dimensional particle-in-cell simulation initiated with the diagnosed target pre-expansion at -0.2ps and post processed by ray tracing simulations supports the experimental observations and demonstrates the capability of time resolved optical diagnostics to provide quantitative input and feedback to the numerical treatment within the time frame of the relativistic laser-plasma interaction.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2020

Optimization of radiochromic film stacks to diagnose high-flux laser-accelerated proton beams

Here, we extend flatbed scanner calibrations of GafChromic EBT3, MD-V3, and HD-V2 radiochromic films using high-precision x-ray irradiation and monoenergetic proton bombardment. By computing a visibility parameter based on fractional errors, optimal dose ranges and transitions between film types are identified. The visibility analysis is used to design an ideal radiochromic film stack for the proton energy spectrum expected from the interaction of a petawatt laser with a cryogenic hydrogen jet target.

Curry, C. B. (ORCID:000000018756181X)↗
DOE OSTI2022

Hydrogen separation with a graphenylene monolayer: Diffusion Monte Carlo study

Here, we performed fixed-node diffusion Monte Carlo (DMC) calculations to investigate structural and energetic properties of graphenylene (GPNL), a two-dimensional network of sp 2 -bonded carbon atoms with large near-circular pores, and its H 2 separation performance for gas mixtures. We have found that the energetic stability of a GPNL monolayer is comparable to that of γ-graphyne, as evidenced by its large cohesive energy of 6.755(3) eV/atom. Diffusion barriers of several gas molecules, including hydrogen, through a GPNL membrane were determined from the analysis of their adsorption energies depending on the adsorption distance, which led to our estimation for hydrogen selectivity with respect to other target molecules. DMC hydrogen selectivity of a GPNL monolayer was found to be exceptionally high at 300 K, as high as 10 10 –10 11 against CO and N 2 gases. This, along with high hydrogen permeance due to its generic pore structure, leads us to conclude that GPNL is a promising membrane to be used as a high-performance hydrogen separator from gas mixtures. We find that when compared to our DMC results, DFT calculations tend to overestimate H 2 selectivity, which is mostly due to their inaccurate description of short-range repulsive interactions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Absorptive corrections to the electromagnetic form factor in high-energy elastic proton-proton scattering

Recently, it was noted that absorptive corrections to the electromagnetic form factor in high-energy proton-proton scattering are important for the theoretical interpretation of the p ↑ p and p ↑ A analyzing power A N ( t ) measurements with the Hydrogen Jet Target polarimeter (HJET) at RHIC. Here, a concise expression for the absorptive correction was derived within the eikonal approach. The resulting analysis reveals a systematic bias, nearly independent of the beam energy, in the experimental determination of the real-to-imaginary ratio ρ when absorption effects are overlooked in the data analysis. Quantification of this bias, as ρ meas = ρ + ( 0.036 ± 0.016 ) bias , was achieved using a Regge fit applied to available proton-proton measurements of ρ meas ( s ) and σ tot meas ( s ) . Considering the potential impact of such an effect on the experimentally determined A N ( t ) , one may enhance consistency between the HJET and STAR measurements of the hadronic spin-flip amplitude. While the sign of the bias in the value of ρ aligns with the anticipated effective increase in the proton charge radius in p p scattering due to absorption, it amplifies the observed discrepancy between σ tot meas and ρ meas values at s = 13 TeV as measured in the TOTEM experiment. Evaluation (using published TOTEM data) of the measured proton-proton d σ / d t dependence on the absorptive corrections indicated that possible soft photon corrections to the hadronic amplitude slope may be essential for such data analysis. Published by the American Physical Society 2024

43 PARTICLE ACCELERATORS↗
DOE OSTI2023

Precision Small Scattering Angle Measurements of Proton–Proton and Proton–Nucleus Analyzing Powers at the RHIC Hydrogen Jet Polarimeter

At RHIC, the hydrogen jet target polarimeter (HJET) is used to measure proton beam polarization with accuracy $σ^{syst}_{P}$ / $P$ ≲ 0.5% by counting low energy (1–10 MeV) recoil protons in left-right symmetric detectors. The HJET performance also allowed us to precisely measure $pp$ and $pA$ (where $A$ is any ion stored at RHIC) analyzing powers in the CNI region. The results of the measurements are discussed.

43 PARTICLE ACCELERATORS↗
NASA NTRS1983

Modification of the photoionization of hydrogen by a low-frequency laser

The modification of the photoionization cross section due to the presence of an intense low-frequency laser is obtained for the hydrogen-atom target. Previous calculations of this effect have neglected the effects of the Coulomb potential in the final state. A sum rule was obtained which indicates that the photoelectric current is unaffected by the presence of the low-frequency laser to lowest order in the laser frequency. It is found that the Coulomb potential changes this result and that the photoelectric current is changed by a factor which depends upon the laser parameters and the electron momentum. A simple experiment is suggested to confirm this prediction.

Fiordilino, E.↗
NASA NTRS1985

Theory and calculation of resonances and autoionization of two-electron atoms and ions

Techniques for calculating the electron scattering from one-electron hydrogen-like targets on the basis of the Feshback formalism, are discussed. The principal similarities between resonance parameters in the Feshbach formalism and the corresponding Breit-Wigner quantities, are described in detail. Special attention is devoted to a description of the Fano line shape parameter q, and a technique for formulating it in terms of a projector operator is proposed. The theoretical methods are illustrated by numerical calculations for 1S, 3P, and 1D states of H(-) below the first excited threshold of the target atom. Calculations of 1,3S 1,3P, 1,3D states for He are also presented.

Temkin, A.↗
NASA NTRS1997

Ultra Heavy Ion Collector (UHIC)

The purpose of this final report is to study the propagation of heavy nuclei in cosmic radiation. Topics include: Mass Distributions of Fragments from the Interactions of 600 MeV/n Silver Nuclei; Charge-pickup by Heavy Relativistic Nuclei; Fragmentation and Propagation Heavy UH Cosmic Ray Nuclei; Nuclear Fragmentation Parameters Needed for Interpretation of Observed Fluxes of UH Cosmic Ray Nuclei; Fragmentation and Electromagnetic Dissociation of 10.6 GeV/nucleon (197) Au Nuclei; Nuclear Interaction Cross Sections for UltraHeavy Nuclei; The Charge-Changing Fragmentation of 10.6 GeV/nucleon 197 Au Nuclei; Fragmentation Cross Sections of Relativistic 84/36 Kr and 109/47 Ag Nuclei in Targets from Hydrogen to Lead; Mission Concept for the Study of Ultraheavy Galactic Cosmic Rays; and Propagation of the Heaviest UH - Cosmic Ray Nuclei.

Stone, E. C.↗
NASA NTRS1980

Electron Capture into Rydberg States According to the Born Approximation: Correction of an Error

A general expression is derived for the Born amplitude for electron capture into high principal, and arbitrary angular momentum, quantum numbers, n and l, by bare nuclei from hydrogenic atom targets. Cross sections for capture into high n and l = 0,1 are given in analytic forms. The limiting values of the ratios of the Born over OBK cross sections for n >> 1 and l = 0,1 are found, and shown that they confirm the empirical law of Jackson and Schiff only approximately. For high angular momenta, it is shown that the Born cross section approaches the OBK cross section. An error in a previous publication by the author has been corrected.

Omidvar, Kazem↗