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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

A perspective on iron (Fe) in the atmosphere: air quality, climate, and the ocean

As scientists engage in research motivated by climate change and the impacts of pollution on air, water, and human health, we increasingly recognize the need for the scientific community to improve communication and knowledge exchange across disciplines to address pressing and outstanding research questions holistically. Our professional paths have crossed because our research activities focus on the chemical reactivity of Fe-containing minerals in air and water, and at the air-sea interface. (Photo)chemical reactions driven by Fe can take place at the surface of the particles/droplets or within the condensed phase. The extent and rates of these reactions are influenced by water content and biogeochemical activity ubiquitous in these systems. One of these reactions is the production of reactive oxygen species (ROS) that cause damage to respiratory organs. Another is that the reactivity of Fe and organics in aerosol particles alter surficial physicochemical properties that impact aerosol-radiation and aerosol–cloud interactions. Also, upon deposition, aerosol particles influence ocean biogeochemical processes because micronutrients such as Fe or toxic elements such as copper become bioavailable. We provide a perspective on these topics and future research directions on the reactivity of Fe in atmospheric aerosol systems, from sources to short- and long-term impacts at the sinks with emphasis on needs to enhance the predictive power of atmospheric and ocean models.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Understanding the Deactivation of Ag–ZrO 2 /SiO 2 Catalysts for the Single-step Conversion of Ethanol to Butenes

Ag–ZrO 2 /SBA-16 has recently been found to be efficient for catalyzing the single-step conversion of ethanol to butene (1- and 2-butene mixtures) in the presence of H 2 . The reaction proceeds via a cascading sequence of reactions over mixed metal and Lewis sites, with the catalyst composition tuned to selectively favor butene formation. However, the catalyst slowly deactivates when evaluated over long reaction times. Here, we evaluated the lifetime of the Ag–ZrO 2 /SBA-16 catalyst system for ethanol-to-butene conversion at 325 °C for up to 800 hours on stream. Several characterization techniques were used to elucidate the mechanism(s) by which catalyst deactivation occurs. Coke deposition, Ag particle sintering, and Ag 0 -to-Ag + oxidation state change were identified to be the major causes of catalyst deactivation. Coke deposits cover primarily Lewis acid sites which are responsible for aldol condensation, Meerwein-Ponndorf-Verley (MPV) reduction, and dehydration reactions. Ag particle sintering and Ag oxidation state change leads to a reduction in the number of metallic Ag sites responsible for the dehydrogenation/hydrogenation steps. The fresh catalyst likely experiences hydrothermal sintering in the early stage of reaction and permanently loses some active Lewis acid sites before reaching a new structural steady state. The deactivation of Lewis acid sites leads to a decrease in overall ethanol conversion, whereas the deactivation of the metallic Ag sites decreases the butene selectivity. For catalyst regeneration, oxidative calcination (at 500 °C) followed by reduction (at 325 °C) successfully removes all the coke species on the catalyst surface and restores the metallic Ag particles of the 4Ag–4ZrO 2 /SBA-16 catalysts.

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

Status Update: Deposition Modeling For SNF Canister CISCC

This report fulfills the M3 milestones M3SF-21PN010207025 & M3SF-20PN0102070412. During fiscal year (FY) 2020, Pacific Northwest National Laboratory (PNNL) worked to further develop the FY 2019 deposition and particle tracking models. This status report outlines these efforts and presents the progress made so far. Model development work is ongoing and is planned to continue in FY 2021. The FY 2020 model development included work on: Wind Effects. Model development and sensitivity studies, investigated how wind direction and speed affect deposition; Brownian Motion. Implementing Brownian Motion into existing models; Particle Size Variability. Depending on the particle composition, the diameter of the particle may vary with changes in relative humidity. Models were developed to analyze this; Multiphase and Fluid Film Modeling. Investigating canister surface wetting and drying, and how this effects overall deposition. Models were developed to analyze this; Difusophoresis. Performing initial work to implement diffusiophoresis into the existing models; Turbophoresis. Performing initial work to implement turbophoresis into the existing models. Much of this work will continue into FY21. The authors present initial results and discus current and future work.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS2006

Temperature Effects in the ATIC BGO Calorimeter

The Advanced Thin Ionization Calorimeter (ATIC) Balloon Experiment contains a segmented calorimeter composed of 320 individual BGO crystals (18 radiation lengths deep) to determine the particle energy. Like all inorganic scintillation crystals the light output of BGO depends not only on the energy deposited by particles but also on the temperature of the crystal. ATIC had successful flights in 2000/2001 and 2002/2003 from McMurdo, Antarctica. The temperature of balloon instruments varies during their flights at altitude due to sun angle variations and differences in albedo from the ground and is monitored and recorded. In order to determine the temperature sensitivity of the ATIC calorimeter it was temperature cycled in the thermal vacuum chamber at the CSBF in Palestine, TX. The temperature dependence is derived from the pulse height response to cosmic ray muons at various temperatures.

Isbert, J.↗
NASA NTRS1978

Scanning Electron Microscopy and Petrography of Glassy Particles Produced by Lava Fountain Eruptions

A conceptual model of a lava fountain consists of a vent, spatter ramparts, fountain column, downwind plume and associated pumice deposits. Glassy particles produced by lava fountain eruptions consist primarily of sideromelane glass and minor to moderate amounts of vesicles and crystals. Particles are classified on the basis of morphology as: (1) spherical, (2) elongate, (3) glass-coated mineral grain, (4) shard, (5) reticulite, (6) composite particle, and (7) lithic fragment.

Ladle, G. H.↗
DOE OSTI2020

Physical and hydrodynamic properties of deep sea mining-generated, abyssal sediment plumes in the Clarion Clipperton Fracture Zone (eastern-central Pacific)

The anthropogenic impact of polymetallic nodule harvesting in the Clarion-Clipperton Fracture Zone is expected to strongly affect the benthic ecosystem. To predict the long-term, industrial-scale impact of nodule mining on the deep-sea environment and to improve the reliability of the sediment plume model, information about the specific characteristics of deep-sea particles is needed. Discharge simulations of mining-related fine-grained (median diameter ≈ 20 µm) sediment plumes at concentrations of 35–500 mg L –1 (dry weight) showed a propensity for rapid flocculation within 10 to 135 min, resulting in the formation of large aggregates up to 1100 µm in diameter. The results indicated that the discharge of elevated plume concentrations (500 mg L –1 ) under an increased shear rate (G ≥ 2.4 s –1 ) would result in improved efficiency of sediment flocculation. Furthermore, particle transport model results suggested that even under typical deep-sea flow conditions (G ≈ 0.1 s –1 ), rapid deposition of particles could be expected, which would restrict heavy sediment blanketing (several centimeters) to a smaller fall-out area near the source, unless subsequent flow events resuspended the sediments. Planning for in situ tests of these model projections is underway.

42 ENGINEERING↗
NASA NTRS2013

Biological Effects of Particles with Very High Energy Deposition on Mammalian Cells Utilizing the Brookhaven Tandem Van de Graaff Accelerator

High LET radiation from GCR (Galactic Cosmic Rays) consisting mainly of high charge and energy (HZE) nuclei and secondary protons and neutrons, and secondaries from protons in SPE (Solar Particle Event) pose a major health risk to astronauts due to induction of DNA damage and oxidative stress. Experiments with high energy particles mimicking the space environment for estimation of radiation risk are being performed at NASA Space Radiation Laboratory at BNL. Experiments with low energy particles comparing to high energy particles of similar LET are of interest for investigation of the role of track structure on biological effects. For this purpose, we report results utilizing the Tandem Van de Graaff accelerator at BNL. The primary objective of our studies is to elucidate the influence of high vs low energy deposition on track structure, delta ray contribution and resulting biological responses. These low energy ions are of special relevance as these energies may occur following absorption through the spacecraft and shielding materials in human tissues and nuclear fragments produced in tissues by high energy protons and neutrons. This study will help to verify the efficiency of these low energy particles and better understand how various cell types respond to them.

Saha, Janapriya↗
DOE OSTI2025

Identification of contamination in the pulse-compression chamber of the OMEGA EP Laser System originating from clean room garments

The contamination of optical components with microscopic particles strongly impacts their ability to handle high-power or high-intensity laser pulses via an array of mechanisms. This work explores the nature and origin of a subset of contamination particles found inside the pulse-compression chamber of the OMEGA EP Laser System. Using Raman microscopy accompanied by other analytical methods, it was shown that sodium nitrate constitutes a significant fraction of the particles that possess diameters on the order of a few micrometers. Further investigation aiming to reveal the origin of these particles suggests that these sodium nitrate particles are deposited via shedding from the reusable clean room garments worn in the Laser Bay and compression chamber. Raman microscopy also revealed various plastic particles such as polystyrene, polyethylene, and poly(diallyl isophthalate).

Raman spectroscopy↗
DOE OSTI2022

Continuous Light Absorption Photometer (CLAP) Instrument Handbook

Reliable measurements of aerosol light absorption are crucial for quantifying the radiative forcing of climate. As a consequence, light absorption measurements are recommended for all stations in the Global Atmosphere Watch network, which is coordinated by the World Meteorological Organization. Aerosol light absorption is often dominated by soot-like particles produced by the incomplete combustion of carbonaceous fuels, commonly termed "black carbon", and optical methods are the primary way that equivalent black carbon concentrations are derived. Two basic approaches are used for determining the aerosol light absorption coefficient: in situ methods where the absorption is measured while the particles are suspended in air, and filter-based methods where the particles are deposited on a filter for real-time optical analysis. In situ methods are inherently more accurate because the physical state of the particles can be changed by the act of filtration. Unfortunately, currently available instruments for in situ measurements are more expensive and difficult to operate than filter-based methods, making them better suited for use in intensive field campaigns or as laboratory reference instruments. Filter-based instruments, because of their lower cost and simpler operation, have been the preferred choice for long-term measurements of aerosol light absorption in monitoring networks.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1986

Agglomeration-Free Distributor for Fluidized Beds

New gas distributor for fluidized beds prevents hot particles from reacting on it and forming hard crust. In reduction of iron ore in fluidized bed, ore particles do not sinter on distributor and perhaps clog it or otherwise interfere with gas flow. Distributor also relatively cool. In fluidized-bed production of silicon, inflowing silane does not decompose until within bed of hot silicon particles and deposits on them. Plates of spiral distributor arranged to direct incoming gas into spiral flow. Turbulence in flow reduces frequency of contact between fluidized-bed particles and distributor.

Ouyang, F.↗
NASA NTRS2002

A Low LET Radiation Spectrometer for Measuring Particle Doses in Space and Aircraft

This paper presents experimental data that demonstrates the feasibility of fabricating a miniature nuclear particle dosimeter for monitoring doses in aircraft and satellites. The basic instrument is a Low Linear-Energy-Transfer (LET) Radiation Spectrometer (LoLRS) that is designed to measure the energy deposited by particles with low LET values. The heart of the instrument is a Silicon-Lithium Drifted Diode (SLDD). Test results show that the LoLRS can be used to monitor the radiation threat to personnel in flights of space- and aircraft and also to generate a comprehensive data base from aviation and satellite measurements that can contribute to the formulation of more accurate environmental radiation models for dose predictions with reduced uncertainty factors.

Stassinopoulos, E. G.↗
NASA NTRS1984

Mars - Experimental study of albedo changes caused by dust fallout

A laboratory apparatus was used to simulate the uniform fallout and deposition of particles 1 to 5 microns in diameter in an experimental study on how the spectral and photometric properties of representative Martian areas are affected by fallout of atmospheric dust (smaller than or equalling 60 microns) suspended during dust storms. In this study, measurements are made in the changes in reflectance at optical and near-infrared wavelengths (0.4 to 1.2 micron) caused by deposition of varying amounts of a Mars-analog dust on bright and dark substrates before and after deposition of 6 x 10 to the -5th to 1.5 x 10 to the -3rd g/sq cm of simulated fallout. It is believed that only small amounts of dust particles (approximately 3 x 10 to the -4th g/sq cm) are needed to make significant albedo changes in dark areas of Mars, and that this would rule out uniform dust deposition on the surface of the planet. Data also indicate that other high albedo features like bright crater-related wind streaks may not be areas of significant sediment deposits. Laboratory simulations have permitted estimates of how much the reflectance of an area on Mars would change given a certain amount of dust fallout (g/sq cm) or reflectance data. These simulations may also be useful in tracking the transport and deposition of the dust.

Wells, E. N.↗
DOE OSTI2024

A Self Consistent 2D Simulation of Coherent Synchrotron Radiation Effects on Beam Dynamics

An increasing interest in high quality and high current electron beams necessitates a thorough understanding and prediction of coherent synchrotron radiation effects. The self-interaction of charged particles in a beam undergoing synchrotron motion is a physically significant process that is all too often computationally intensive with very little analytical results to rely on for the general case. The coherent spectrum of this interaction is of utmost importance to the design of free electron lasers (FELs) and an accurate assessment is imperative for their design. This work presents a novel implementation to the numerical simulation of charged particle beams. The simulation is a self-consistent approach including the self-fields generated by the beam of which coherent synchrotron radiation effects are of primary interest. A particle-in-cell model is used where a planar beam sampled by point particles is deposited on an encompassing grid at each timestep. The electromagnetic fields are calculated on the grid using the retarded potentials according to causality. The electromagnetic forces from the fields are interpolated on each particle which in turn advance in time. The simulation is benchmarked against well-established results for coherent synchrotron radiation effects. In addition, studies are provided that show the convergence of simulation results for increasing resolution. A study into the transverse beam size effects on beam dynamics is performed as well as a proof of concept where the simulation is used by a genetic algorithm to optimize the design parameters of a beam lattice. The results of these studies in tandem verify the efficacy of the simulation for its practical use in accelerator design or the study of synchrotron radiation effects

Duffin, Dallan [Old Dominion Univ., Norfolk, VA (U↗
NASA NTRS1989

Microgravity particle research on the Space Station - The gas-grain simulation facility

In the gravitational field on earth, the large settling rate of micron-sized particles and the effects of gravity-induced convection prohibit many interesting studies of phenomena such as coagulation, collisions, and mutual interactions of droplets, dust grains and other particles. Examples of exobiology experiments involving these phenomena are the simulation of organic aerosol formation in Titan's atmosphere, studies of the role of comets in prebiotic chemical evolution, and simulations of carbon grain interactions in various astrophysical environments. The Gas-Grain Simulation Facility (GGSF) is a proposed earth-orbital laboratory that will allow present ground-based experimental programs which study processes involving small particles and weak interactions to be extended to a new domain. Physics issues that scientists wishing to propose GGSF experiments must consider are reviewed in this paper. Specifically, coagulation, motion in gases and vacua, and wall deposition of particles in a microgravity environment are discussed.

Fogleman, G.↗
DOE OSTI2021

Synthesis and Morphological Characterization of Electroless-Deposited Ni-P Coatings on Diamond Abrasives

Deposition of a coating on rough surfaces faces unique challenges due to the complexity of substrate morphology. In the present research, electroless deposition of a Ni-P coating was successfully deposited on diamond particles. Microtomography was conducted to study the deposition mechanisms. It revealed that the coating coverage rate on diamond particles was affected by the synergistic action of the deposition time, substrate morphology, and hypophosphite concentration. The best coverage was achieved in a solution with 0.2 mol/L hypophosphite. Two major morphological features of the coating: nodular and smooth, were influenced by the deposition parameters, coating integrity, and substrate morphology. The failure was seen in fractured and peeled off coatings. It was due to residual stress produced by the coalescing of crystallites during the deposition. This failure mechanism explains the tendency of coating fracture at three morphological features of the substrate. This work is beneficial to semiconductor manufacturing where effective cutting in chip fabrication is essential.

36 MATERIALS SCIENCE↗
DOE OSTI2024

The Triple Component Interface of Ni–Co–Ce: Growth, Chemical State, and Stability of NiCo Bimetallic Particles on Reducible CeO 2 (111) Thin Films

The growth of NiCo particles at low coverages over reducible CeO 2 (111) thin films producing a triple interface between Ni-Co-Ce was investigated by scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS), which was compared to that of monometallic Ni and Co particles. XPS data show that deposition of either Ni or Co on CeO 2 at 300 K causes a partial reduction of Ce 4+ cations to Ce 3+ ions. At 0.3 monolayer (ML), XPS detects Co 2+ on CeO 2 . However, both Ni 0 and Ni 2+ are present as major species at 300 K and annealing causes a significant increase of Ni 2+ in Ni particles. Deposition of 0.3 ML Co over 0.3 ML Ni on CeO 2 at 300 K induces reduction of Ni 2+ to metallic Ni and Ni 0 was found as predominant species. Unlike for Co/CeO 2 , metallic Co was also present over the Co-Ni/CeO 2 surface in addition to Co 2+ . Further, this behavior indicates the formation of NiCo bimetallic particles with the possibility of Co diffusion to the interface of Ni/ceria. With heating, the intermixing of Ni and Co atoms in bimetallic particles on CeO 2 was facilitated. Furthermore, oxidation of both metals and ceria occurred as a result of the diffusion of lattice oxygen from the bulk of ceria to the surface. A slight increase in Ni 2+ was observed after heating Co-Ni/CeO 2 to 500 K or higher. Co became Co 2+ with heating to 800 K. Our STM results confirm the formation of NiCo bimetallic particles on CeO 2 at 300 K and further suggest that the addition of Co can help inhibit the sintering of Ni particles at higher temperatures. Bimetallic particles were also obtained by depositing Ni over existing Co particles on CeO 2 . However, our XPS data demonstrate that the deposition order of Co and Ni plays a role in the chemical state of these two metals in bimetallic particles, likely attributed to the difference in their compositions at the bimetallic particle surface as well as the metal-support interface.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2017

Analysis of CO2 Composite Spray Cleaning System Results

In a previous study, the cleaning efficiency of a CO2 composite cleaning system for particulate removal was tested. The study covered particles from spores to fluorescent particles of different sizes as well as a variety of substrate surfaces, including aluminum, titanium, stainless steel, and nitinol. Particles were deposited using aerosol (dry) and droplet (wet) deposition. Results from the previous study show that the CO2 composite spray system is capable of cleaning to sterility for aerosol deposited spores and is capable of cleaning a minimum of a 4-log reduction for droplet deposited spores. This minimum 4-log reduction matches current Planetary Protection dry heat microbial reduction requirements. In this paper we will present new data to further correlate the cleaning efficiency with how contamination was introduced to the surface, the surface roughness, and particle size. Possible causes for such correlations will be discussed.

Chung, Shirley↗
NASA NTRSDate not supplied

Uniform Dust Deposition System for Dust Tolerance Studies

Future missions to the Moon will require mechanisms and materials to effectively and reliably operate in the presences of lunar regolith. One of the challenges of developing such technologies is terrestrial testing with lunar dust simulants. Dust has a stochastic nature of depositing and it can be difficult to accurately apply it to surfaces of interest. Deposition density, particles size distribution, and percent coverage are all factors that affect the quality of dust mitigation testing. Therefore, to enable such testing the dust mitigation and seals teams at NASA Glenn Research Center (GRC) have developed a system that can uniformly and repeatably deposit lunar simulants on a range of surfaces. Testing of the Dust Deposition System (DDS) and an associatedsimulant preparation methodology have quantified the levels of uniformity and precision for this system. Furthermore, the deposition system has been paired with automated micrograph capturing and machine learning image analysis to correlate the images of dust on a surface to deposition density (in g/cm2). This correlation alleviates the need for tested samples to be accurately weighed with milligram precision and may be a useful tool for in-situ contamination evaluation on the Moon. This paper covers the design and validation testing for the DDS.

Stephen Gerdts↗