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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 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Electromagnetic rifle with spin-stabilized projectile

An EM driver for accelerating an object may be configured as an EM rifle for accelerating, rotating to spin-stabilize, and releasing a projectile. A core includes a stator coil, forward and reverse coils, a railed shaft, and a transfer shaft. The stator coil generates a first EM field, and the forward and reverse coils generate second and third EM fields which interact with the first EM field to accelerate the armature in forward and reverse directions, respectively. The railed shaft is elongated along a central axis through the armature and includes multiple rails arranged helically around a central shaft. The armature remains in contact with the rails during acceleration so as to impart a turning motion. The transfer shaft is physically coupled with and projects forwardly from the armature and transfers to the projectile the acceleration and the turning motion of the armature in the forward direction.

Timpson, Erik↗
DOE OSTI2021

Electromagnetic driver with helical rails to impart rotation

An EM driver for accelerating an object may be configured as an EM rifle for accelerating, rotating to spin-stabilize, and releasing a projectile. A core includes a stator coil, forward and reverse coils, a railed shaft, and a transfer shaft. The stator coil generates a first EM field, and the forward and reverse coils generate second and third EM fields which interact with the first EM field to accelerate the armature in forward and reverse directions, respectively. The railed shaft is elongated along a central axis through the armature and includes multiple rails arranged helically around a central shaft. The armature remains in contact with the rails during acceleration so as to impart a turning motion. The transfer shaft is physically coupled with and projects forwardly from the armature and transfers to the projectile the acceleration and the turning motion of the armature in the forward direction.

Timpson, Erik↗
DOE OSTI2021

Electromagnetic driver with forward and reverse coils

An EM driver for accelerating an object may be configured as an EM rifle for accelerating, rotating to spin-stabilize, and releasing a projectile. A core includes a stator coil, forward and reverse coils, a railed shaft, and a transfer shaft. The stator coil generates a first EM field, and the forward and reverse coils generate second and third EM fields which interact with the first EM field to accelerate the armature in forward and reverse directions, respectively. The railed shaft is elongated along a central axis through the armature and includes multiple rails arranged helically around a central shaft. The armature remains in contact with the rails during acceleration so as to impart a turning motion. The transfer shaft is physically coupled with and projects forwardly from the armature and transfers to the projectile the acceleration and the turning motion of the armature in the forward direction.

Timpson, Erik↗
DOE OSTI2023

Electromagnetic rifle with compact armature

An EM driver for accelerating an object may be configured as an EM rifle for accelerating, rotating to spin-stabilize, and releasing a projectile. A core includes a stator coil, forward and reverse coils, a railed shaft, and a transfer shaft. The stator coil generates a first EM field, and the forward and reverse coils generate second and third EM fields which interact with the first EM field to accelerate the armature in forward and reverse directions, respectively. The railed shaft is elongated along a central axis through the armature and includes multiple rails arranged helically around a central shaft. The armature remains in contact with the rails during acceleration so as to impart a turning motion. The transfer shaft is physically coupled with and projects forwardly from the armature and transfers to the projectile the acceleration and the turning motion of the armature in the forward direction.

Timpson, Erik Joseph↗
DOE OSTI2020

Image-enhanced bipolaron formation at organic semiconductor/electrode interfaces

We explore the image charge interaction for organic semiconductor bipolarons near a conducting interface and find that the cross term between one of the constituent charges and the image of its neighbor stabilizes the bipolaron by up to ~0.3 eV, dramatically increasing the concentration of this species near the interface. Using density functional theory calculations for the common hole transport molecule N,N'-bis(3-methylphenyl)- N,N'-diphenylbenzidine, we validate a simple point charge description of this effect and incorporate it within an interface energy level alignment model to predict the density of polarons and bipolarons near the interface. We find that the image effect greatly enhances bipolaron formation in the first few monolayers, leading to the expectation that bipolarons account for more than 1% of the total interface charge in many cases of practical interest. Furthermore, this result reinforces the notion that bipolarons are robust near the contacts of many organic semiconductor devices and thus helps to rationalize their involvement in the phenomenon of unipolar organic magnetoresistance.

36 MATERIALS SCIENCE↗
DOE OSTI2022

The Interaction of K and O 2 on Au(111): Multiple Growth Modes of Potassium Oxide and Their Catalytic Activity for CO Oxidation

Abstract In industrial catalysis, alkali cations are frequently used to promote activity or selectivity. Scanning tunneling microscopy, ambient‐pressure X‐ray photoelectron spectroscopy, and density‐functional calculations were used to study the structure and reactivity of potassium oxides in contact with the Au(111) surface. Three different types of oxides (K 2 O 2 , K 2 O and KO y with y <0.5) were observed on top of the gold substrate at 300–525 K. Initially, small aggregates of K 2 O 2 /K 2 O (1–2 nm in size) were seen at the elbows of the herringbone structure. After increasing the K coverage (>0.15 ML), large islands of the oxide (20–40 nm in size) appeared. These islands contained a mixture of K 2 O and KO y ( y <0.5). A key correlation was found involving the structure, oxidation state, and chemical activity of the alkali oxide. The small aggregates of potassium oxide had a very high catalytic activity for the oxidation of CO, being much more than plain promoters.

Shi, Rui↗
DOE OSTI2022

The Interaction of K and O 2 on Au(111): Multiple Growth Modes of Potassium Oxide and Their Catalytic Activity for CO Oxidation

Abstract In industrial catalysis, alkali cations are frequently used to promote activity or selectivity. Scanning tunneling microscopy, ambient‐pressure X‐ray photoelectron spectroscopy, and density‐functional calculations were used to study the structure and reactivity of potassium oxides in contact with the Au(111) surface. Three different types of oxides (K 2 O 2 , K 2 O and KO y with y <0.5) were observed on top of the gold substrate at 300–525 K. Initially, small aggregates of K 2 O 2 /K 2 O (1–2 nm in size) were seen at the elbows of the herringbone structure. After increasing the K coverage (>0.15 ML), large islands of the oxide (20–40 nm in size) appeared. These islands contained a mixture of K 2 O and KO y ( y <0.5). A key correlation was found involving the structure, oxidation state, and chemical activity of the alkali oxide. The small aggregates of potassium oxide had a very high catalytic activity for the oxidation of CO, being much more than plain promoters.

Shi, Rui↗
DOE OSTI2021

PBI nanofiber mat-reinforced anion exchange membranes with covalently linked interfaces for use in water electrolysers

Anion exchange membranes (AEM) are key components in anion exchange membrane water electrolysers. Recently developed materials are less susceptible to the alkaline degradation of the polymer backbone and quaternary ammonium groups. A remaining challenge is the mechanical stability in contact with hot water and dimensional stability when the temperature of the feed solution changes. One solution is to reinforce membranes with a porous support. Since support materials like PEEK or PTFE have a different swelling behavior than the matrix and no strong interactions with the matrix, voids can form, and gas crossover increases. In this work, we approach this issue by pore filling polybenzimidazole nanofiber mats with the bromomethylated precursor of mTPN, an ultra-stable AEM material. During drying, a covalent interaction between support (PBI amine groups) and matrix (-CH 2 Br) is established. After quaternization, the optimized PBI/mTPN-50.120 composite membrane still shows a high conductivity of 62 mS cm –1 , but 37% reduced length swelling in comparison to the non-reinforced membrane. Tensile strength and Young's modulus increase 17% and 56% to 49 MPa and 680 MPa, respectively. In an electrolyser, a stable voltage of 1.98V at 0.25 A cm –2 was achieved, and no change in membrane resistance was observed over the test time of 200 h (50°C, 1 M KOH, catalysts based on Ni/Fe and Mo).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Improved Self-Assembly of P3HT with Pyrene-Functionalized Methacrylates

A block copolymer with discotic liquid crystalline behavior was synthesized using Grignard metathesis polymerization (GRIM) and initiators for continuous activator regeneration atom transfer radical polymerization (ICAR-ATRP). A novel discotic liquid crystalline mesogen, 6-(pyren-1-yloxy)hexyl methacrylate (PyMA), comprises a block that is attached to regioregular poly(3- hexylthiophene) (rr-P 3 HT) generated by GRIM and subjected to end-group modification. Due to the continuous regeneration of Cu + in the reaction mixture in ICAR-ATRP compared to conventional methods, the synthesis was successfully performed with less catalyst. The purity and yield of the final product are increased by eliminating rigorous post-synthesis purification. Stacked pyrene units have contributed to the enhanced long-range π-π interactions and aligning of the P 3 HT block as observed in thin-film X-ray diffraction (XRD). Furthermore, field-effect mobilities in the order of 10 -2 cm 2 V -1 s -1 in bottom-gate, top-contact organic field-effect transistors (OFETs) suggest an enhancement in charge transport due to the discotic electron-rich pyrene units that help mitigate the insulating effect of the methacrylate backbone. The formation of uniform microdomains of P 3 HT-bpoly(PyMA) observed with tapping mode atomic force microscopy (TMAFM) on the channel regions of OFETs indicates the unique packing of the block copolymer in comparison to pristine P 3 HT. Thermotropic properties of the novel discotic mesogen in the presence and absence of P3HT were observed with both the poly(3-hexylthiophene)-b-poly(6-(pyren-1-yloxy)hexyl methacrylate) (P3HT-b-poly(PyMA)) block copolymer and poly(6-(pyren-1-yloxy)hexyl methacrylate) (poly(PyMA)) homopolymer using polarized optical microscopy (POM) and differential scanning calorimetry (DSC).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Search for Solar Boosted Dark Matter Particles at the PandaX-4T Experiment

We present a novel constraint on light dark matter utilizing 1.54 metric ton/year of data acquired from the PandaX-4T dual-phase xenon time projection chamber. This constraint is derived through detecting electronic recoil signals resulting from the interaction with solar-enhanced dark matter flux. Low-mass dark matter particles, lighter than a few MeV / c 2 , can scatter with the thermal electrons in the Sun. Consequently, with higher kinetic energy, the boosted dark matter component becomes detectable via contact scattering with xenon electrons, resulting in a few keV energy deposition that exceeds the threshold of PandaX-4T. We calculate the expected recoil energy in PandaX-4T considering the Sun’s acceleration with heavy mediators and the detection capabilities of the xenon detector. The first experimental search results using the xenon detector yield the most stringent upper limits cross section of 3.51 × 10 − 39 cm 2 at 0.08 MeV / c 2 for a solar boosted dark matter mass ranging from 0.02 to 10 MeV / c 2 , achieving a 23-fold improvement compared with earlier experimental studies. Published by the American Physical Society 2025

Shen, Guofang↗
DOE OSTI2023

NCSU Flux Tower Data

NCSU Flux Tower Data Level b1: QC checks applied to measurements Data Format: CSV Description: See "instrument descripotion Site: Houston, TX; Tracking Aerosol Convection interactions ExpeRiment (HOU) Location: Houston, TX; AMF1 (main site for TRACER) Facility Code: M1 Category: Aerosol Properties Data Type: PI Data Source Instrument/Data: Sonic Anemometer, 3 Condensation Particle Counters, 1 SP2, 1 POPS Start Date: 2022-06-01 End Date: 2022-9-26 Contact PI: Markus Petters (mdpetter@ncsu.edu) Funding Source: DOE ASR award US Department of Energy, Office of Science, Biological and Environment Research (grant no. DE-SC 0021074) Instrument description The NCSU flux tower was located next to the AMF sampling pad. The flux tower consisted of a 10 m telescoping tower. Mounted at the top of the tower was a sonic anemometer (RM Young 8000) and a Krypton Hygrometer. A sample line (¼” conductive tubing) and communication line was laid to a trailer located underneath and slightly adjacent to the tower. The sample line brought aerosol inside the trailer at 4.5 L min-1, where it was distributed between 3 CPCs (TSI 3776c, Dc ~ 2.5 nm, TSI 3771, Dc ~10nm, and TSI 3772, Dc ~40 nm) with different size cuts. Also sampling was a printed particle optical spectrometer (POPS) and a single particle soot photometer (SP2). Please contact mdpetter@ncsu.edu for further information.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Study of alkaline carbonate cooling to mitigate Ex-Vessel molten corium accidents

To mitigate adverse effects from molten corium following a reactor pressure vessel failure (RPVF), some new reactor designs employ a core catcher and a sacrificial material (SM), such as ceramic or concrete, to stabilize the molten corium and avoid containment breach. Existing reactors cannot easily be modified to include these SMs but could be modified to allow injectable cooling materials. Current reactor designs are limited to using water to stabilize the corium, but this can create other issues such as reaction of water with the concrete forming hydrogen gas. Here the novel SM proposed is a granular carbonate mineral that can be used in existing light water reactor plants. The granular carbonate will decompose when exposed to heat, inducing an endothermic reaction to quickly solidify the corium in place and producing a mineral oxide and carbon dioxide. Corium spreading is a complex process strongly influenced by coupled chemical reactions, including decay heat from the corium, phase change, and reactions between the concrete containment and available water. A recently completed Sandia National Laboratories laboratory directed research and development (LDRD) project focused on two research areas: experiments to demonstrate the feasibility of the novel SM concept, and modeling activities to determine the potential applications of the concept to actual nuclear plants. Small-scale experiments using lead oxide (PbO) as a surrogate for molten corium demonstrate that the reaction of the SM with molten PbO results in a fast solidification of the melt due to the endothermic carbonate decomposition reaction and the formation of open pore structures in the solidified PbO from CO 2 released during the decomposition. A simplified carbonate decomposition model was developed to predict thermal decomposition of carbonate mineral in contact with corium. This model was incorporated into MELCOR, a severe accident nuclear reactor code. A full-plant MELCOR simulation suggests that by the introduction of SM to the reactor cavity prior to RPVF ex-vessel accident progression, e.g., core-concrete interaction and core spreading on the containment floor, could be delayed by at least 15 h; this may be enough for additional accident management to be implemented to alleviate the situation.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2020

Conductive Thin Films over Large Areas by Supramolecular Self-Assembly

We report a “one-step” method for preparing conductive thin films with cylindrical microdomains oriented normal to the surface over large areas using the supramolecular assembly of poly(styrene-block-4-vinylpyridine) (PS19-b-P4VP 5 ) and 5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphine (HOTPP). HOTPP interacts with the P4VP block by hydrogen bonding between the hydroxyl group of HOTPP and pyridine ring of PS 19 -b-P4VP 5 , forming cylindrical P4VP(HOTPP) domains having an average diameter of ~17 nm in a PS matrix. Here, dynamic light scattering, contact angle, and in situ grazing incidence small-angle X-ray scattering measurements show a morphological transition from spherical micelles in solution to cylindrical microdomains oriented normal to the substrate surface during the drying process. From the dependence of current on voltage, an average current of ~4.0 nA is found to pass through a single microdomain, pointing to a promising route for organic semiconductor device applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Hypothetical Efficiency of Electrical to Mechanical Energy Transfer during Individual Stochastic Molecular Switching Events

There are now many examples of single molecule rotors, motors and switches in the literature that, when driven by photons, electrons or chemical reactions, exhibit well defined motions. As a step towards using these single molecule devices to perform useful functions one must understand how they interact with their environment and quantify their ability to perform work on it. Using a single molecule rotary switch we examine the transfer of electrical energy, delivered via electron tunneling, to mechanical motion and measure the forces the switch experiences with a non-contact q-plus atomic force microscope. Action spectra reveal that the molecular switch has two stable states and can be excited resonantly between them at a bias of 100 mV via a one-electron inelastic tunneling process which corresponds to an energy input of 16 zepto Joules. Furthermore, while the electrically induced switching events are stochastic and no net work is to done on the cantilever, by measuring the forces between the molecular switch and the AFM cantilever we can derive the maximum hypothetical work the switch could perform during a single switching event which is ~55 meV, equal to 8.9 zepto Joules which translates to a hypothetical efficiency ~55% per individual inelastic tunneling electron induced switching event. When co considering the total electrical energy input this drops to 1x10 -7 % due to elastic tunneling events that dominate the tunneling current. However, this approach constitutes a general method for quantifying and comparing the energy input and output of molecularmechanical devices.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Probing the influence of ion-pairing on ligand-field excited-state dynamics

Exploration of the photophysical and photochemical properties of transition metal complexes has driven ground-breaking advancements in solar energy conversion technologies, including photoredox catalysis. While significant research has been devoted to understanding excited state properties of second- and third-row transition metal complexes, earth-abundant first-row metal complexes have received comparatively little attention in this context until very recently. In particular, the role of ion-pairing – which has been identified as a potentially significant factor for Ir(III)-based photosensitizers – has not been examined with regard to its influence on the ligand-field excited states that dominate much of first-row photophysics. A key challenge in studying ion-pair interactions lies in quantifying the extent and nature of ion-pairing, particularly in non-aqueous media where the vast majority of photophysical studies are performed. Cobalt(III) polypyridyl complexes provide an attractive platform to address such questions due to their demonstrated potential for applications in photoredox catalysis involving ligand-field excited states. In the present study, we prepared a cobalt(III) polypyridyl complex, [Co(4,4′-OMebpy) 3 ](BAr F 4 ) 3 (where 4,4′-OMebpy is 4,4′-dimethoxy-2,2′-bipyridine and BAr F 4 is tetrakis(3,5-bis(trifluoromethyl)-phenyl)borate) to probe ion-pairing in non-aqueous solutions. Specifically, analysis of data acquired from both variable-temperature diffusion ordered spectroscopy (DOSY) NMR and 1-D rotating-frame nuclear Overhauser effect (ROE) experiments allowed us to identify and differentiate between solvent-separated ion pairs in high-dielectric media and contact ion pairs in a low-dielectric solvent. Time-resolved absorption spectroscopy was then used to measure ground-state recovery dynamics under these varying conditions of ion-pairing, the results of which revealed an increase in excited-state lifetime for contact ion-pairs that we suggest arises from a reduction in outer-sphere reorganization energy relative to conditions which favored solvent-separated ion pairs. We believe this study demonstrates that one can leverage broadly available NMR-based methods to understand ion-pairing in non-aqueous solutions, which in turn can provide a microscopic picture of intermolecular interactions that can impact the photophysical properties of transition metal-based chromophores.

Ghosh, Atanu [Michigan State University, East Lans↗
DOE OSTI2026

Wildfire-Power Grid Interactions: Feedback, Impacts, Monitoring, Modeling, and Mitigation Strategies

Wildfires are increasingly interacting with electric power systems through a two-way hazard chain: fires damage grid assets and trigger cascading outages, while grid faults can ignite new fires under hot, dry, and windy conditions. This review synthesizes the state of knowledge across five domains: (i) physical impacts of flames, heat, and smoke on lines, towers, insulators, and substations; (ii) power-infrastructure-initiated ignitions via conductor clash, high-impedance faults, and corona discharge; (iii) widespread blackouts and disproportionate societal impacts; (iv) multi-scale monitoring spanning laboratory tests, in-situ and grid-integrated sensors, and Earth observation; (v) coupled modeling that links fire behavior with grid operations; and (vi) technological and strategic mitigation pathways spanning prevention, response, and recovery. We integrate these domains into a novel 'feedback-aware' socio-technical framework. Through a longitudinal analysis (2005-2025) of global incidents, we identify that while vegetation contact remains the most frequent ignition source, aging infrastructure failure has emerged as a critical driver of catastrophic 'mega-fires'. We further identify persistent gaps, including limited interoperability of high-frequency grid and environmental data, scarce real-time data assimilation, and under-developed equity metrics for outage management. We conclude by outlining a research agenda to (1) deploy interoperable sensing architectures, (2) advance feedback-coupled fire-grid simulations, and (3) evaluate mitigation portfolios through techno-economic and fairness lenses. Recognizing wildfire-grid interactions as coupled socio-technical systems is essential for protecting infrastructure and communities and for ensuring reliable, sustainable electricity in a changing world.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2020

Passivated Interfaces and Surface Recombination Velocities in Halide Perovskites

Surfaces and charge-extracting contacts remain major sources of non-radiative recombination loss; limiting the performance of perovskite PV compared to theoretical limits. We investigate mixed-cation mixed-halide perovskites and demonstrate that, with chemical surface passivation, they can achieve >4 μs minority carrier lifetimes, and >20% external PL quantum yields (PLQY), and nearly single-exponential decay kinetics. This high PLQY observed corresponds to ~97% of the Shockley-Queisser theoretical quasi-fermi level splitting, a first for MA-free mixed-cation mixed-halide compositions. The high PLQY and long PL lifetimes allow us to measure average surface recombination velocities (SRV) <10cm/s, with a champion low of ~1cm/s (a conservative estimate). We show how such improvements in SRV should lead to an absolute improvement in PCE of >4% even with the best of contact alignments. We investigate different MA-free high bandgap compositions, including bandgaps relevant for tandem applications (1.7-1.8eV), and demonstrate performance improvements across all these compositions with our surface passivation strategy. Lastly, using a combination of surface characterization techniques, we show Lewis base interactions of the passivating agent with the perovskite surfaces.

14 SOLAR ENERGY↗