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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

A Statistical Study of Solar Particle Events in Flux and Dose

The high-energy protons from solar energetic particle (SEP) events present a hazard to space systems: damage to science instruments/electronics/materials or to astronauts. A reliable estimate of the high-energy proton environment is critical to assure mission success. Important characteristics of an SEP event are fluence, peak flux, energy spectrum, time to reach the peak flux, time to reach peak dose, and properties of the cumulative dose profile after an event starts. All of these characteristics are important to understand in order to design space missions properly for both robotic and human missions. Because of the unpredictable and sporadic nature of SEP events, statistical models are often used to represent the SEP parameters described above. In a study by Jun et al. (2007), the statistics of event fluences, durations, and time intervals between events were investigated using the then available historical SEP dataset obtained from the instruments onboard the IMP-8 spacecraft. Since then, a more comprehensive SEP dataset based off of IMP-8 and GOES called Reference Data Set Version 2.0 (RDSv2.0) has become available covering the SEP events up to Year 2015 under a framework of the European Space Agency's (ESA's) Solar Energetic Particle Environment Modelling (SEPEM) project (Jiggens et al., 2018). The main objectives of this statistical study of SEP events are two-fold: First, the statistics of peak fluxes, event fluences, durations, and time intervals will be re-visited by using RDSv2.0; Second, the statistical analyses of flux and dose timing will be performed using the same dataset RDSv2.0. The results of this study will address the statistical properties of all key parameters for designing a spacecraft or a human mission where the SEP environment is an important consideration.

Whitman, K.↗
DOE OSTI2025

High-energy ion beams generated with high efficiency using laser-driven 3D microstructures

Laser-driven ion acceleration in plasma is being proposed as a source of ion beams with a high peak current that can be useful in many fields of science and medicine. Using this method, high proton energies have been achieved by increasing the laser power and by using ultrathin (≤ 200 nm) foils. However, this approach is limited by survivability of the nanotargets to laser prepulses and by difficulty in controlling the plasma acceleration properties. Here, we introduce a new target platform using two-photon polymerization, 3D laser-printed “clone” microstructures with average densities lower than solid that are relatively insensitive to the laser prepulse. Two types of microstructured targets consisting of either a multilayered log-pile or a stochastic arrangement of one micron diameter wires are used. Both demonstrate a higher energy and higher yield proton acceleration compared to thin solid-density foil targets by the robust target normal sheath acceleration (TNSA) mechanism. We find that when such 10–20 μm thick structures are irradiated with a petawatt laser, protons with energies up to 110 MeV and a laser-to-proton conversion efficiency of ~ 10% are obtained. Our work suggests that such microstructures optimized for 60–200 MeV compact proton accelerators are promising for future radiotherapy and other applications.

Physics - Plasma physics↗
DOE OSTI2021

Electron Activity (Secondary Electron & Field Emission ) Suppression by Magnetic Field Placed on the Surface of Metals And Dielectric [Slides]

Secondary electron emission happens when the surface is exposed to an oscillating electromagnetic field. It has extremely dangerous effect when resonance condition of this oscillating field and higher SEY conditions are met. The dependence of the secondary electron on primary electron energy is shown in the figure. This multiplication effect on the number of electrons in oscillating electromagnetic field is called multipacting. The problem with multipacting exist in many scientific fields like LHC, ISS, ITER involving particle accelerator, space science and fusion research. In high intensity proton rings this multiplies electron get trapped inside the potential created by proton beam called electron cloud. In High power microwave sources, rf couplers and rf window to couple the power also hugely affected by multipacting.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS2008

Innermost Van Allen Radiation Belt for High Energy Protons at Saturn

The high energy proton radiation belts of Saturn are energetically dominated by the source from cosmic ray albedo neutron decay (CRAND), trapping of protons from beta decay of neutrons emitted from galactic cosmic ray nuclear interactions with the main rings. These belts were originally discovered in wide gaps between the A-ring, Janus/Epimetheus, Mimas, and Enceladus. The narrow F and G rings significant affected the CRAND protons but did not produce total depletion. Voyager 2 measurements subsequently revealed an outermost CRAND proton belt beyond Enceladus. Although the source rate is small, the trapping times limited by radial magnetospheric diffusion are very long, about ten years at peak measured flux inwards of the G ring, so large fluxes can accumulate unless otherwise limited in the trapping region by neutral gas, dust, and ring body interactions. One proposed final extension of the Cassini Orbiter mission would place perikrone in a 3000-km gap between the inner D ring and the upper atmosphere of Saturn. Experience with CRAND in the Earth's inner Van Allen proton belt suggests that a similar innermost belt might be found in this comparably wide region at Saturn. Radial dependence of magnetospheric diffusion, proximity to the ring neutron source, and northward magnetic offset of Saturn's magnetic equator from the ring plane could potentially produce peak fluxes several orders of magnitude higher than previously measured outside the main rings. Even brief passes through such an intense environment of highly penetrating protons would be a significant concern for spacecraft operations and science observations. Actual fluxes are limited by losses in Saturn's exospheric gas and in a dust environment likely comparable to that of the known CRAND proton belts. The first numerical model of this unexplored radiation belt is presented to determine limits on peak magnitude and radial profile of the proton flux distribution.

Cooper, John F.↗
DOE OSTI2020

Cryogenic Liquid Jets for High Repetition Rate Discovery Science

In this paper, we present a detailed procedure for the operation of continuous, micron-sized cryogenic cylindrical and planar liquid jets. When operated as described here, the jet exhibits high laminarity and stability for centimeters. Successful operation of a cryogenic liquid jet in the Rayleigh regime requires a basic understanding of fluid dynamics and thermodynamics at cryogenic temperatures. Theoretical calculations and typical empirical values are provided as a guide to design a comparable system. This report identifies the importance of both cleanliness during cryogenic source assembly and stability of the cryogenic source temperature once liquefied. The system can be used for high repetition rate laser-driven proton acceleration, with an envisioned application in proton therapy. Other applications include laboratory astrophysics, materials science, and next-generation particle accelerators.

42 ENGINEERING↗
DOE OSTI2022

Hadron-Induced Radiation Damage in Fast Heavy Inorganic Scintillators

Fast and heavy inorganic scintillators with suitable radiation tolerance are required to face the challenges presented at future hadron colliders of high energy and intensity. Up to 5 GGy and 5 × 1018 neq/cm2 of one-MeV-equivalent neutron fluence is expected by the forward calorimeter at the Future Hadron Circular Collider. This paper reports the results of an investigation of proton- and neutron-induced radiation damage in various fast and heavy inorganic scintillators, such as LYSO:Ce crystals, LuAG:Ce ceramics, and BaF2 crystals. The experiments were carried out at the Blue Room with 800 MeV proton fluence up to 3.0 × 1015 p/cm2 and at the East Port with one MeV equivalent neutron fluence up to 9.2 × 1015 neq/cm2, respectively, at the Los Alamos Neutron Science Center. Experiments were also carried out at the CERN PS-IRRAD proton facility with 24 GeV proton fluence up to 8.2 × 1015 p/cm2. Research and development will continue to develop LuAG:Ce ceramics and BaF2:Y crystals with improved optical quality, F/T ratio, and radiation hardness.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2023

Poly(diallylmethylammonium) proton conducting membranes with high ionic conductivity at intermediate temperatures

High temperature proton exchange membrane fuel cells are being lately investigated because of their high energy efficiency, their superior heat/water management, CO tolerance, and electrode reaction kinetics. To further advance this technology, the polymer membrane portfolio and performance should be improved for intermediate or high temperature operation (>100 °C). In this work we present new poly(diallylmethylammonium) proton conducting membranes with high ionic conductivity at 120 °C. First, new protic ionic liquids, hereafter called DAMAH + X - , were synthesized leading to diallylmethylammonium monomers with different counter-anions. By radical cyclopolymerization through thermal and photoinitiation mechanisms, self-standing protic polymeric membranes of poly(diallylmethylammonium X - ) were obtained. Membranes showed good thermal stability (>250 °C) and mechanical properties without the need of additives such as (protic) ionic liquids, solvents or inorganic charges. Great attention was paid to understand the effect of the different counter-anions on the membrane properties. As a general trend, fluorinated anions coming from strong acids confer high ionic conductivity and allow to reduce the hygroscopic properties on the protic polymeric membranes. Proton structural and dynamical stability at different temperatures and humidification conditions were investigated by Neutron Scattering (QENS and NR). The optimized poly(diallylmethylammonium X - ) shows similar ionic conductivity values than Nafion 212 under varying relative humidity conditions at 80 °C. Furthermore, it shows a high ionic conductivity value of 1.9 × 10 -3 Scm -1 at 120 °C under dry conditions.

08 HYDROGEN↗
DOE OSTI2026

Elucidating hydrogen isotope transport mechanisms in proton-conducting ceramics with trapping effects using TMAP8

Hydrogen isotopes play an central role in many science and engineering applications such as fuel cells, hydrogen production, and fusion energy. For these applications, hydrogen separation and extraction applications are pivotal aspects of hydrogen transports, where proton-conducting ceramics (PCCs) have shown great potential. In this study, we propose a new model for hydrogen isotope transport in PCC materials, BaZr 0.9 Y 0.1 O 2.95 (BZY) in particular, which captures behavior in both dry and wet environments. The model expands previous efforts and considers diffusion, trapping, and surface reactions (i.e., dissociation and recombination). We then validate and calibrate the model using deuterium transport measurements from experiments in both dry and wet environments. This study highlights the key role of trapping, often neglected, on hydrogen isotope transport in BZY and other PCC materials. It also explains how the commonly observed discrepancy between dry and wet behavior can be attributed to more active surface reactions and saturated traps due to the increased hydrogen presence under the wet environment. These results provide insights to optimize PCC manufacturing and usage as a hydrogen separation and extraction technology in various fields, emphasizing that lowering the trapping can reduce hydrogen isotope retention. These modeling and calibration efforts are performed using the tritium migration analysis program, version 8 (TMAP8), an open-source application designed for hydrogen isotope transport.

36 - MATERIALS SCIENCE↗
DOE OSTI2024

Engineering of a Coupled Nanocomposite as a High-Performance Protonic Ceramic Fuel Cell Cathode

The lack of high-performance cathode catalysts is a salient issue that bedeviled the commercialization of protonic ceramic fuel cells (PCFCs). Here, in this work, we report a remarkable electrocatalytic activity and stability enhancement of cathode electrodes by engineering a coupled nanocomposite. The as-prepared Pr 0.3 (Ba 0.5 Sr 0.5 ) 0.7 Co 0.8 Fe 0.2 O 3−δ nanocomposite possesses a bulk cubic phase on which homogeneous and intimate orthorhombic PrCo 0.5 Fe 0.5 O 3−δ nanoparticles are uniformly decorated. X-ray diffraction and Raman spectroscopy reveal the excellent thermal stability of the nanocomposite. It achieves a high peak power density of 1.02 W cm –2 based on protonic electrolytes at 600 °C. No noticeable structural degradation is observed over ∼210 h at 550 °C according to scanning electron microscopy analysis. This work demonstrates an effective strategy to boost the performance of perovskite oxides for PCFCs via nanocomposite engineering. It may apply to other catalyst designs and discoveries, such as for batteries, electrolyzers, and membrane reactors.

08 - HYDROGEN↗
NASA NTRS1974

Skylab neutron environment experiment (Science Demonstration SD-34 (TV108)). Description and preliminary results

Neutron and proton induced radioactivity at various locations within Skylab were measured. Samples of five metals were formed into activation packets and deployed at the following locations on the Skylab 4 mission: orbital workshop film vault, water storage tank, and two opposing orbital workshop internal locations. Radioactive nuclides were produced in the packets by nuclear interactions of high-energy protons and secondary neutrons within Skylab. Low-level gamma ray spectroscopy measurements were made on the returned packets to determine the incident neutron and proton fluxes and spectra and their variations with mass distribution.

Fishman, G. J.↗
DOE OSTI2020

Dimer interaction in the Hv1 proton channel

The voltage-gated proton channel Hv1 is a member of the voltage-gated ion channel superfamily, which stands out in design: It is a dimer of two voltage-sensing domains (VSDs), each containing a pore pathway, a voltage sensor (S4), and a gate (S1) and forming its own ion channel. Opening of the two channels in the dimer is cooperative. Part of the cooperativity is due to association between coiled-coil domains that extend intracellularly from the S4s. Interactions between the transmembrane portions of the subunits may also contribute, but the nature of transmembrane packing is unclear. Using functional analysis of a mutagenesis scan, biochemistry, and modeling, we find that the subunits form a dimer interface along the entire length of S1, and also have intersubunit contacts between S1 and S4. These interactions exert a strong effect on gating, in particular on the stability of the open state. Our results suggest that gating in Hv1 is tuned by extensive VSD–VSD interactions between the gates and voltage sensors of the dimeric channel.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Low-Cost, High Performance Catalyst Coated Membranes for PEM Water Electrolyzers (Final Technical Report)

In this project, the objective was to develop reduced-cost manufacturing techniques capable of producing proton exchange membrane water electrolyzer (PEMWE) catalyst coated membranes (CCMs) with further improved performance relative to then-current 3M CCM technology. Processes to be developed would enable 1) production of 0.5 m wide CCMs (approximately 2x wider than produced by the current laboratory/pilot-scale processes) and 2) 3x higher net-effective linear rates (lineal-meters of CCM produced per cumulative process time) than the baseline CCM process. In combination, the wider width CCM and increased net-effective linear rates would result in a 6-fold decrease in CCM manufacturing cost (defined as cumulative machine and labor time) per m 2 of CCM produced. PEMWE CCMs produced with these optimized processes were targeted to produce 1) 0.25 A/cm 2 or greater at 1.5 V, 2) 2.0 A/cm 2 or greater at 1.75 V and 3) 4 A/cm 2 or greater at 1.95V, 4) with total catalyst platinum-group metal (PGM) loadings of ≤ 0.50 mg/cm 2 , measured in a cell with 50 cm 2 active area (or larger) at 80°C cell temperature and ambient outlet pressures.

08 HYDROGEN↗
DOE OSTI2021

Emulation of neutron damage with proton irradiation and its effects on microstructure and microchemistry of Zircaloy-4

This work assesses the potential of proton irradiation to simulate the neutron damage to the matrix and laves phase Zr(Fe,Cr) 2 precipitates in Zircaloy-4. Isothermal proton irradiation has been performed on Zircaloy-4 samples at irradiation temperatures ranging from 250 to 350 °C. Two-step proton irradiation was also performed to enhance the amorphization of and iron loss from the laves phase Zr(Fe,Cr) 2 precipitates. The irradiated microstructures, including dislocation loops and rafts near SPPs, were observed in proton irradiated Zircaloy-4, which are consistent with neutron irradiated material at a similar damage level. The amount of irradiation-induced hardening after proton irradiation was similar to post neutron irradiated data. The significant amorphization of the SPPs and concurrent Fe redistribution observed on neutron irradiated materials can be effectively emulated using a two-step proton irradiation on Zircaloy-4. Hence, the neutron irradiation effect on Zircaloy-4 can be mostly captured using the two-step proton irradiation described in this study.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Commissioning of the IOTA Proton Injector

The Proton Injector for the IOTA storage ring (IPI) is being constructed at the Fermilab Accelerator Science and Technology facility (FAST). It will be a machine capable of delivering 20 mA pulses of protons at 2.5 MeV. IPI will operate alongside the existing electron injector beamline to facilitate further beam physics research and the continued development of novel accelerator technologies at the IOTA ring. This report details the results of the initial commissioning of IPI and an overview of the upcoming experiments with intense proton beams at IOTA.

43 PARTICLE ACCELERATORS↗
DOE OSTI2026

Probing the 𝑗 dependence of angular distributions and 𝑁=20 shell rigidity via the 36 S (𝑝,𝑑) 35 S reaction

An investigation of the N=20 36 S nucleus has been performed through a detailed study of the 3 6S (p,d)3 5S neutron-removal reaction, employing a 66-MeV proton beam at iThemba Laboratory for Accelerator Based Sciences and an innovative target design. Using the high-resolution K = 600 magnetic spectrometer, 98 states in 3 5S were identified up to 16-MeV excitation energy, including 47 previously unobserved states. Angular distributions and spectroscopic factors, including isobaric analog-state contributions, were extracted for 81 levels. A pronounced j dependence in the angular distributions of ℓ=2 states provides refined insights into the spin-orbit splitting. Finite-range adiabatic distorted-wave approximation calculations qualitatively reproduce the observed j dependence. Comparisons of the measured 1d 5/2 spectroscopic strength distribution with large-scale shell-model and ab initio calculations show good agreement overall, and the robustness of the N=20 shell closure in 36 S is confirmed when comparing the relatively low fp orbital occupancies in 40 Ca and 3 6S across the Fermi surface. This study underscores the utility of neutron-removal reactions in probing nuclear structure and the Fermi surface of sd nuclei and beyond. The findings advance our understanding of shell evolution and offer constraining data for theoretical models.

20 ≤ A ≤ 38↗