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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS2012

Development of Complexity Science and Technology Tools for NextGen Airspace Research and Applications

The objective of this research by NextGen AeroSciences, LLC is twofold: 1) to deliver an initial "toolbox" of algorithms, agent-based structures, and method descriptions for introducing trajectory agency as a methodology for simulating and analyzing airspace states, including bulk properties of large numbers of heterogeneous 4D aircraft trajectories in a test airspace -- while maintaining or increasing system safety; and 2) to use these tools in a test airspace to identify possible phase transition structure to predict when an airspace will approach the limits of its capacity. These 4D trajectories continuously replan their paths in the presence of noise and uncertainty while optimizing performance measures and performing conflict detection and resolution. In this approach, trajectories are represented as extended objects endowed with pseudopotential, maintaining time and fuel-efficient paths by bending just enough to accommodate separation while remaining inside of performance envelopes. This trajectory-centric approach differs from previous aircraft-centric distributed approaches to deconfliction. The results of this project are the following: 1) we delivered a toolbox of algorithms, agent-based structures and method descriptions as pseudocode; and 2) we corroborated the existence of phase transition structure in simulation with the addition of "early warning" detected prior to "full" airspace. This research suggests that airspace "fullness" can be anticipated and remedied before the airspace becomes unsafe.

Holmes, Bruce J.↗
DOE OSTI2017

Enhancement of bronze alloy surface properties by FSP second-phase particle incorporation

This study presents results of an experimental study to evaluate friction stir processing (FSP) with and without hard second-phase particle incorporation as a means to enhance surface properties and wear performance of C86300 manganese bronze alloy. FSP of flat bronze alloy specimens was conducted with hardened H-13 tool steel to create a 3-mm-thick processed surface layer. The process was also used to incorporate B 4 C particles, thereby creating a metal-matrix composite layer on the alloy surface. FSP alone was observed to produce substantial reduction in grain size (from an initial value of 350 mu m to 1-5 μm). FSP without particle incorporation resulted in modest surface hardening due to grain refinement and dispersion hardening. Under lubricated contact in block-on-ring testing with a hardened steel counter face, FSP produced substantial reduction (about 3X) in bronze wear after polishing of processing surface roughening. FSP with hard B 4 C second-phase particle incorporation further reduced wear by up to 20X. The improvement in wear behavior is attributed to grain refinement and load shielding by second-phase particles, as determined by wear mechanism analysis.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Benchmark Problems of the Geothermal Technologies Office Code Comparison Study

A diverse suite of numerical simulators is currently being applied to predict or understand the performance of enhanced geothermal systems (EGS). To build confidence and identify critical development needs for these analytical tools, the United States Department of Energy, Geothermal Technologies Office has sponsored a Code Comparison Study (GTO-CCS), with participants from universities, industry, and national laboratories. A principal objective for the study was to create a community forum for improvement and verification of numerical simulators for EGS modeling. Teams participating in the study were those representing U.S. national laboratories, universities, and industries, and each team brought unique numerical simulation capabilities to bear on the problems. Two classes of problems were developed during the study, benchmark problems and challenge problems. The benchmark problems were structured to test the ability of the collection of numerical simulators to solve various combinations of coupled thermal, hydrologic, geomechanical, and geochemical processes. This class of problems was strictly defined in terms of properties, driving forces, initial conditions, and boundary conditions. Study participants submitted solutions to problems for which their simulation tools were deemed capable or nearly capable. Some participating codes were originally developed for EGS applications whereas some others were designed for different applications but can simulate processes similar to those in EGS. Solution submissions from both were encouraged. In some cases, participants made small incremental changes to their numerical simulation codes to address specific elements of the problem, and in other cases participants submitted solutions with existing simulation tools, acknowledging the limitations of the code. The challenge problems were based on the enhanced geothermal systems research conducted at Fenton Hill, near Los Alamos, New Mexico, between 1974 and 1995. The problems involved two phases of research, stimulation, development, and circulation in two separate reservoirs. The challenge problems had specific questions to be answered via numerical simulation in three topical areas: 1) reservoir creation/stimulation, 2) reactive and passive transport, and 3) thermal recovery. Whereas the benchmark class of problems were designed to test capabilities for modeling coupled processes under strictly specified conditions, the stated objective for the challenge class of problems was to demonstrate what new understanding of the Fenton Hill experiments could be realized via the application of modern numerical simulation tools by recognized expert practitioners.

15 GEOTHERMAL ENERGY↗
DOE OSTI2020

Progress Toward Simulating Departure from Nucleate Boiling at High-Pressure Applications with Selected Wall Boiling Closures

Recently, a Eulerian-based two-fluid computational fluid dynamics (CFD) framework with a wall heat flux partitioning approach has been intensively investigated for departure from nucleate boiling (DNB) simulation under the U.S. Department of Energy–funded Consortium for Advanced Simulation of Light Water Reactors (CASL) program. Understanding of the DNB characteristics over a range of pressurized water reactor–like operating conditions and accurate prediction of boiling crisis in the nuclear power system have been grand challenges because of the large impact of DNB on reactor safety and operational economics. The ultimate goal of this task in the CASL program is to introduce a robust multiphase CFD–based DNB modeling framework that is capable of characterizing an entire boiling history in which the wall boiling mode experiences the following through multiple stages of heat transfer mode: (1) single-phase convective heat transfer, (2) nucleate boiling heat transfer, and (3) identification of the departure of nucleate boiling. To validate the CASL boiling model, we have benchmarked simulated DNB over three different flow channel configurations (pipe flow, 5 × 5 fuel bundle with mixing vane tests, and 5 × 5 fuel bundle without mixing vane tests) against experimental measurements, and the validation result with open literature is reported. The DNB detection criteria in the simulation are checked by monitoring the peak wall temperature, wall dryout factor, and net energy balance. In addition to the DNB performance test, some preliminary sensitivity results on closure model selection are reported to address the prediction capability of local void profile against measurements. The boiling simulation tested in this study exhibits a maximum deviation of 24% from the measured DNB value in a high-pressure (i.e., 138 bars) subcooled pipe flow test. The ranges of operating conditions are as follows: 1650 to 2650 kg/m 2 ·s for mass flux and 8.5 to 96 K for subcooled inlet temperature. The deviation is even reduced to 7% when the subcooled temperature is less than 40 K. Besides accuracy, base practice guidelines for DNB detection criteria are tested by monitoring three simulation variables: (1) maximum wall temperature, (2) wall dryout factor (i.e., K-value), and (3) energy balance. Numerical robustness of DNB simulation is largely achieved in most of the validation test except for a few high subcooled test cases.

42 ENGINEERING↗
DOE OSTI2017

Research on the influence of anaerobic stabilization of various dairy sewage sludge on biodegradation of polycyclic aromatic hydrocarbons PAHs with the use of effective microorganisms

Sewage sludge was taken from a dairy WWTP belonging to Mlekovita Cooperative in Wysokie Mazowieckie. There were excess sludge, flotation sludge and a mixture of excess and flotation sludge from pre-treatment of dairy sewage. The initial content of 16 PAHs in excess sludge before fermentation was approximately 689 µg·kg{sup −1} in dry mass, whereas in post-flotation sludge (which constituted around 30% of raw sludge) it was approximately 95 µg·kg{sup −1} in dry mass. A mixture of excess and flotation sludge had the content of 497,7 µg·kg{sup −1} in dry mass. Through comparison of particular hydrocarbons content in raw sewage sludge to the total PAHs content, it was shown that tricyclic compounds, which constituted 46,3% of the PAHs sum (excess sludge), and tetracyclic compounds, which constituted 60,0% of the PAHs sum (flotation sludge), were the dominating fractions. In the sludge subjected to fermentation in reactors with mixed sludge and surplus activated sludge, the general trend of the course of changes in concentrations of PAHs was similar. Both in the sludge inoculated with EM and in that not inoculated with EM, a significant increase in the total PAHs contents was observed in the first fermentation phase (acidic fermentation) after 7 days of the process. Addition of EM into the sludge did not prevent the PAHs release, and therefore higher concentrations of PAHs sum were recorded during the hydrolysis stage than in sludge before fermentation. A decrease in the sum of PAHs was observed after 2 weeks of fermentation in relation to the quantity observed after 1 week of fermentation (except from post-flotation sludge). In the following weeks, there was further decrease in the concentration of the 16 PAHs sum in all sludge types. However, in sludge without EM inoculation, it was lower than in sludge with EM inoculation. The loss of the majority of tested hydrocarbons was reported in the final phase of fermentation. - Highlights: • The influence of applying Effective Microorganisms on PAHs degradation in dairy sewage sludge during fermentation has been examined. • To study the relationship between quantitative parameters and to describe the correlation strength, Spearman's rank correlation coefficient was used. • In order to verify whether there was a statistically significant change, the Wilcoxon test was applied for individual observation pairs.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1990

Advanced Stirling receiver development program, phase 1

Critical technology experiments were designed and developed to evaluate the Stirling cavity heat pipe receiver for a space solar power system. Theoretical criteria were applied to the design of a module for containing energy storage phase change material while avoiding thermal ratcheting. Zero-g drop tower tests, without phase change, were conducted to affirm that the bubble location required to avoid ratcheting could be achieved without the use of container materials that are wetted by the phase change material. A full scale module was fabricated, but not tested. A fabrication method was successfully developed for the sodium evaporator dome, with a sintered screen wick, to be used as the focal point for the receiver. Crushing of the screen during hydroforming was substantially reduced over the results of other researchers by using wax impregnation. Superheating of the sodium in the wick under average flux conditions is expected to be under 10K. A 2000K furnace which will simulate solar flux conditions for testing the evaporator dome was successfully built and tested.

Lurio, Charles A.↗
DOE OSTI2023

Solution combustion synthesis of iron-based alumina catalysts for dehydrogenation of fossil fuels

Microwave-assisted thermocatalytic dehydrogenation of fossil fuels has been proposed as a method for hydrogen production with no CO2 emissions. The byproduct is carbon, which has a commercial value. Iron-based alumina nanocomposites are promising catalysts for this process as they both absorb microwave radiation and catalyze the dehydrogenation. In addition, they may have magnetic properties, which could be used for their separation from the carbon byproduct. Solution combustion synthesis (SCS) is an attractive technique for the fabrication of iron-based alumina nanocomposites because it can produce high specific surface area oxides in a facile manner. However, the effects of the heating mode, the fuel, and the iron/aluminum ratio on the combustion synthesis behavior and the product properties have not been studied yet. In the present work, the iron-based alumina nanocomposites were obtained by SCS using a hotplate, a muffle furnace, and a microwave oven. The initial mixtures were aqueous solutions of iron nitrate, aluminum nitrate, and an organic fuel. The concentrations of the two nitrates were varied in proportion to Fe:Al molar ratios of 1:2, 1:1, and 2:1. Two fuels were tested: citric acid and glycine. The combustion was less vigorous when citric acid was used as the fuel, which is explained by the lower exothermicity of the reaction. X-ray diffraction analysis of the products confirmed the formation of complex oxides of Fe and Al, specifically it detected hercynite and magnetite phases. Brunauer-Emmett-Teller surface area analysis has shown that the powders obtained using citric acid have specific surface areas as high as 276 m2/g, significantly higher than those obtained using glycine. Muffle furnace and hotplate heating led to comparable specific surface areas, while microwave heating resulted in significantly lower specific surface areas. The magnetic properties of the products increase with increasing the Fe/Al molar ratio from 1:2 (no response to a magnetic field) to 1:1 (weak response) and 2:1 (strong response).

solution combustion synthesis, nanoscale oxides, f↗
DOE OSTI2020

Standard versus non-standard CP phases in neutrino oscillation in matter with non-unitarity

We formulate a perturbative framework for the flavor transformation of the standard active three neutrinos but with a non-unitary flavor mixing matrix, a system which may be relevant for the leptonic unitarity test. We use the $\alpha$ parametrization of the non-unitary matrix and take its elements $\alpha_{\beta \gamma}$ ($\beta,\gamma = e,\mu,\tau$) and the ratio $\epsilon \simeq \Delta m^2_{21} / \Delta m^2_{31}$ as the small expansion parameters. Two qualitatively new features that hold in all the oscillation channels are uncovered in the probability formula obtained to first order in the expansion: (1) The phases of the complex $\alpha$ elements always come into the observable in the particular combination with the $\nu$SM CP phase $\delta$ in the form $[e^{- i \delta } \bar{\alpha}_{\mu e}, ~e^{ - i \delta} \bar{\alpha}_{\tau e}, ~\bar{\alpha}_{\tau \mu}]$ under the Particle Data Group convention of a unitary $\nu$SM mixing matrix. (2) The diagonal $\alpha$ parameters appear in particular combinations $\left( a/b - 1 \right) \alpha_{ee} + \alpha_{\mu \mu}$ and $\alpha_{\mu \mu} - \alpha_{\tau \tau}$, where $a$ and $b$ denote, respectively, the matter potential due to charged current and neutral current reactions. This property holds only in the unitary evolution part of the probability, and there is no such feature in the genuine non-unitary part, while the $\delta$–$\alpha$ parameter phase correlation exists for both. The reason for such remarkable stability of the phase correlation is discussed.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Deformation and fracture characteristics of Al6092/SiC/17.5p metal matrix composite sheets due to heat treatments

Highlights: • Al{sub 2}Cu, Al{sub 4}Cu{sub 2}Mg{sub 8}Si{sub 7} and MgAl{sub 2} precipitations are formed between Al-matrix and SiC particle interface after T6-treatement • O-condition annealing decrease Al{sub 2}Cu intermetallic compound and increase elongation to fracture • 6092Al/SiCp composite at O-condition annealing is more sensitive to strain rate than the one heat treated by T6-treatment • Dimple density in the fracture surface of Al/SiCp composite varies as a function of heat treatment and strain rate - Abstract: In metal matrix composite (MMC) materials, the reaction between the metal matrix and reinforcement particles could change the composition of the matrix and the interface and lead to interfacial compounds. These intermetallic compounds may have either a deleterious effect to the mechanical properties or beneficial effect in enhancing the toughness and ductility of the composite. An aluminium 6092 alloy with 17.5% volume fraction silicon carbide (SiC) particles sheet manufactured by means of powder metallurgical method, heat treated to T6 condition, is used to obtain a fundamental understanding of the heat treatment effect on the fracture mechanism, the microstructural changes and the interface between the Al-matrix and SiC particles. Changes in the microstructure of the Al/SiCp and the topography of the fracture are investigated using scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM) to characterize the precipitate and intermetallic compounds formed at the Al/Sic interface. X-ray diffraction (XRD) is utilized to characterize the phase formation and to give confidence in the results of TEM and EDS. Tensile tests with different strain rates (8 × 10{sup −5}, 8 × 10{sup −4}, 8 × 10{sup −3}, 8 × 10{sup −2} and 0.16 s{sup −1}) were carried out to study the toughness and to find a correlation between the strain rate and heat treatment. Under T6 condition, the results show that the mechanical property of this MMC is less ductile due to the formation of precipitations as a result of either the interaction between the Al and SiCp or from hardening precipitation treatment, e.g. Al{sub 2}Cu, Al{sub 4}Cu{sub 2}Mg{sub 8}Si{sub 7} and MgAl{sub 2}. O-condition annealing can reduce the detrimental effect of the intermetallic compounds in the interface region and improve the toughness and ductility of the material by decreasing the intermetallic compound (Al{sub 2}Cu). However, the Al/SiC sheet treated with O-condition annealing is more sensitive to the strain rate than the one treated with T6.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Exploring the deformation behavior of nanotwinned Al–Zr alloy via in situ compression

Nanotwinned metals have demonstrated the capacity for concomitant high strength and ductility. However, metals with high stacking fault energies, such as aluminum (Al), have a low propensity for twin formation. Here, we show the fabrication of supersaturated solid-solution Al–Zr alloys with a high density of growth twins. Incoherent twin boundaries (ITBs) are strong barriers to dislocation motion, while mobile partial dislocations promote plasticity. These deformable nanotwinned Al–Zr alloys reach a flow stress of ∼1 GPa, as demonstrated using in situ micropillar compression tests. Density functional theory calculations uncover the role Zr solute plays in the formation and deformation of the nanotwinned microstructure. This study features a strategy for incorporating ITBs and 9R phase into Al alloys for simultaneous benefits to strength and deformability.

Richter, N. A. (ORCID:0000000332732276)↗
DOE OSTI2024

Magnetic phase diagram of a two-orbital model for bilayer nickelates with varying doping

Motivated by the recently discovered high-T c bilayer nickelate superconductor La 3⁢ Ni 2 ⁢O 7 , we comprehensively research a bilayer 2×2×2 cluster for different electronic densities n by using the Lanczos method. We also employ the random-phase approximation to quantify the first magnetic instability with increasing Hubbard coupling strength, also varying n. Based on the spin structure factor S(q), we have obtained a rich magnetic phase diagram in the plane defined by n and U/W, at fixed Hund coupling, where U is the Hubbard strength and W the bandwidth. We have observed numerous states, such as A-AFM, Stripes, G-AFM, and C-AFM. At half-filling, n=2 (two electrons per Ni site, corresponding to N=16 electrons), the canonical superexchange interaction leads to a robust G-AFM state (π,π,π) with antiferromagnetic couplings both in-plane and between layers. By increasing or decreasing electronic densities, ferromagnetic tendencies emerge from the “half-empty” and “half-full” mechanisms, leading to many other interesting magnetic tendencies. In addition, the spin-spin correlations become weaker both in the hole or electron doping regions compared with half-filling. At n=1.5 (or N=12), density corresponding to La 3 ⁢Ni 2 ⁢O 7 , we obtained the “Stripe 2” ground state (antiferromagnetic coupling in one in-plane direction, ferromagnetic coupling in the other, and antiferromagnetic coupling along the z axis) in the 2×2×2 cluster. In addition, we obtained a much stronger AFM coupling along the z axis than the magnetic coupling in the xy plane. The random-phase approximation calculations with varying n give very similar results as Lanczos, even though both techniques are based on quite different procedures. Additionally, a state with q/π=(0.6,0.6,1) close to the E-phase wavevector is found in our RPA calculations by slightly reducing the filling to n=1.25, possibly responsible for the E-phase SDW recently observed in experiments. In conclusion, our predictions can be tested by chemically doping La 3 ⁢Ni 2 ⁢O 7 .

36 MATERIALS SCIENCE↗
DOE OSTI2020

An Investigation of Liquefaction in Irradiated TRIGA Fuel Exposed to Relatively High Temperatures

This report presents the findings of an investigation into high temperature fuel cladding chemical interactions (FCCI) in Training, Research, Isotopes, General Atomics (TRIGA) fuel rods. A TRIGA fuel-rod core or meat is principally composed of uranium (U) particles dispersed in a zirconium hydride (Zr H) matrix. The fuel is clad in sealed 304SS or Incoloy 800 tubes. At high temperatures, the fuel will interact with the cladding, resulting in FCCI. To investigate the FCCI (in this case, liquefaction), irradiated TRIGA fuel rods were exposed to relatively high temperatures in furnace tests. The tests were performed at different temperatures using segments from an irradiated TRIGA fuel rod at the Hot Fuel Examination Facility located at Idaho National Laboratory (INL). The data from this study is important for developing a better understanding of the performance of U-ZrH fuel type during transient events (e.g., a Loss of Coolant Accident (LOCA) event) that may result in high temperatures while operating a TRIGA reactor. Furnace tests were run for 6 hours at 730, 800, 900, 950, and 1,000°C. One test was run for 12 hours at 950°C. Post-test microstructural characterization was performed on the heat-treated samples using optical metallography to look for evidence of liquefaction. Additionally, microstructural characterization was performed using scanning electron microscopy to investigate the microstructure of the as-irradiated fuel before heat treatment and the microstructural changes that occurred after heat treating for the 730 and 950°C heat treatments for 6 hours. Results of the analysis were compared to those produced during diffusion studies performed using unirradiated TRIGA fuel meat and type 304 stainless steel. A gap is typically present in as-irradiated fuel that limits any possibility for chemical interaction between the fuel and cladding. Optical metallography (OM) was used to identify areas in the specimens heat treated at 950 and 1000°C where fuel and cladding contact was satisfactory for the FCCI to transpire. The bulk of the interaction zones that form due to FCCI developed in the fuel meat and not as much in the cladding. Even in the sample tested at 1,000°C, no evidence was found that gross fuel meat or cladding melting had occurred. Only limited porosity was found in the fuel meat that possibly could have been due to melting of a particular precipitate phase or phases that had formed during FCCI. These results agreed with those reported for the unirradiated diffusion couple studies.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2021

Revisions of ORNL 188 W Process Based on Nonradiological Experiments

Tungsten-188 is in widespread use in the 188 W(t 1/2 = 69 d)/ 188 Re(t 1/2 =16.9 h) biomedical generator. Oak Ridge National Laboratory (ORNL) has been providing this product to the world since 1999. At ORNL, 188 W is produced via irradiation in ORNL’s High Flux Isotope Reactor (HFIR). Enriched 186 W targets in the form of sintered metallic pellets or rings achieve a compact loading in the irradiation vessel, providing a high yield per unit target. The enrichment of the target is >90% 186 W and this isotope undergoes double neutron capture to produce the desired 188W product. While 188 W is produced by neutron bombardment, 191 Os(t 1/2 = 15.4 d) is simultaneously produced as a byproduct requiring separation from 188 W by post irradiation treatment. In the current processing pathway, the irradiated W metal pellets or rings are first converted into an oxide form of WO 3 by heating the irradiated W metal target at 750°C in a quartz reaction vessel inside a vertical furnace under a constant flow of air. During heating, W metal reacts with oxygen in the air to produce WO 3 , which is soluble in 6 M NaOH for later purification process. This oxidation process also converts 188 Os (the decay daughter of 188 W) and 191 Os (the irradiation produced byproduct) into OsO 4 , a highly volatile and toxic gas. The gaseous effluents driven from the quartz reaction vessel are passed through a scrubbing array to remove OsO 4 before the air is discharged from the process. This heterogeneous oxidation method simultaneously achieves two goals: 1). converting metal target to a soluble oxide form and 2). separating volatile OsO 4 away from the solid WO 3 product, although harmful 191 OsO 4 is unfavorable but being taken care of by the down road scrubbing array. In the past twenty years the existing OsO 4 scrubbing array served well in preventing OsO 4 from being released into the environment, until July of 2020 when a minor amount of 191 Os was found to have been released into the environment which resulted in a standby of building 4501 from July 2020 to February 2021.Since October 20 of 2020 a team of researchers from groups of RSTD and NEFD were organized to work for the following tasks: (1) Fully understand the root causes of the July incident of 191 Os release and create a redesigned 191 Os scrubbing array to eliminate the possibility of 191 Os release in future 188 W processes; (2) In Phase-1 tests, select a correct air (O 2 ) flow rate in 188 W process, that provides sufficient oxygen for the oxidation of tungsten metal, while still allowing sufficient resonance time for 191 Os removal by the scrubbers; (3) In Phase-2 tests, confirm the efficiency of the redesigned scrubbing array to absorb excessive amount of non-rad OsO 4 (generated from Os metal powder) at the selected air flow; (4) In Phase-3 tests, simulate the hot cell 188 W process by heating pressed non-rad W-Os pellets in a quartz vessel of new design and the new array under operation parameters selected in Phase-1 and -2; (5) Complete a new operation procedure for 188 W process in hot cell and a TM report as a summary of the Os Mitigation Project. This TM report summarizes the investigation on root causes from technical aspects in July 191 Os release and the correspondent improvement towards the redesigned 191 Os scrubbing system. The report presents the efforts made on selection of optimal operational parameter with the new scrubbing array and the quartz vessel of new design, based on experiment data obtained in Phase-1, -2 and -3 tests. Further renovations for 188 W process and additional improvement of W target treatment will also be discussed.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2023

5ω Optical Thomson Scattering Report

The 5ω Optical Thomson Scattering system on the National Ignition Facility (NIF) is a diagnostic designed to measure temporally and spatially resolved plasma conditions in Inertial Confinement Fusion (ICF) Hohlraums. The system was proposed in 2014 and a phased approach to implementation was developed. In phase one the collection system was designed, built, and fielded on the NIF to be used for 3ω Thomson scattering measurements and background measurements near 211 nm (5ω. The initial commissioning experiment for the collection system was completed in Oct. 2016. Commissioning of the collection system continued through 2017 and the system is now fielded for a range of user experiments and regularly produces publication quality data. A dedicated 5ω probe laser was designed and built to allow Thomson scattering measurements in the presence of 2 MJ of 3ω drive energy. Due to scattered light (spectral reflections, laser-plasma instabilities, and unconverted drive energy) from the 3w drive lasers typical wavelengths (2ω and 4ω) fielded at other laser facilities like the Nova Laser Facility and the Omega Laser Facility were unable to meeting the signal to background requirements in design studies. A 10 Joule 5ω probe was proposed as a solution that met requirements. This 10 Joule laser was more energetic than previously fielded 5w lasers by 2-3 orders of magnitude. As part of a risk reduction plan, phase two of the project was to develop a 1 Joule, 5ω laser to demonstrate conversion efficiency >20% from 1ω to 5ω and make initial Thomson scattering measurements in the first few nanoseconds of an ICF laser pulse. Initial tests of the 5w conversion were completed at the Laboratory for Laser Energetics (LLE) and produced record 5ω energies. Based on these results from LLE, a 1 Joule, 5w laser system was designed for the NIF in 2018 and commissioning began in 2019. Commissioning of the 5ω laser system continued through 2023 and was eventually paused in Q1 of FY24 due to completing resource constraints. Commissioning of the 5w laser system proved incredibly challenging. Multiple issues were identified during commissioning and resolved, but issues remain. Currently there is not a clear understanding of why 5ω scattered has not been detected on the OTS collection system. Based on offline measurements, calculations, and preshot measurements the system appears to meet all requirements. Potential target physics issues have been investigated and do not appear to be an issue. The current hypothesis is that there is an error in one or more aspects of the offline testing not translating to expected performance when the system is fielded on the NIF. Additional full system testing in-situ utilizing the complete OTS system and NIF target chamber center time is needed to further test potential failure modes.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1978

Evaluation of a locally homogeneous model of spray evaporation

Measurements were conducted on an evaporating spray in a stagnant environment. The spray was formed using an air-atomizing injector to yield a Sauter mean diameter of the order of 30 microns. The region where evaporation occurred extended approximately 1 m from the injector for the test conditions. Profiles of mean velocity, temperature, composition, and drop size distribution, as well as velocity fluctuations and Reynolds stress, were measured. The results are compared with a locally homogeneous two-phase flow model which implies no velocity difference and thermodynamic equilibrium between the phases. The flow was represented by a k-epsilon-g turbulence model employing a clipped Gaussian probability density function for mixture fraction fluctuations. The model provides a good representation of earlier single-phase jet measurements, but generally overestimates the rate of development of the spray. Using the model predictions to represent conditions along the centerline of the spray, drop life-history calculations were conducted which indicate that these discrepancies are due to slip and loss of thermodynamic equilibrium between the phases.

Shearer, A. J.↗
NASA NTRS1979

Radial diffusion of Io-injected plasma

The paper reexamines the problem of particle injection by Io and subsequent radial diffusion by flux tube interchange using a proper phase space density formulation. The mathematical formalism is developed, and the theoretical results are compared with the observations, taking into account the pitch angle and energy coverage of the detector on Pioneer 10. Two objectives are pursued: (1) to test the hypothesis of Siscoe and Chen (1977) that Io is the source for all of the plasma observed by Frank et al. (1976) inside 10 R(J); and (2) to describe a simple but flexible method intended to analyze the observations of any other plasma instrument flown through the inner Jovian magnetosphere, e.g., those on Voyager 1 and 2 and Galileo.

Goertz, C. K.↗
NASA NTRS1984

Thin metal film and multilayers experiment (A0138-3)

The sources of degradation of in state of the art and newly developed components and testing the usefulness of the concept of storing experiment samples in dry nitrogen under launch and space vacuum conditions during reentry mission phase were investigated. Ultraviolet (UV) and extreme ultraviolet (EUV) experiments suffer degradations during space missions of even 1 month duration. It is suggested that the degradation is due to condensation of outgassing products, followed by solar induced polymerization, however, penetrating charged particles are also known to produce volume effects. Degradation may also start immediately after manufacturing of the component due to oxidation, moisture, or chemical corrosion by atmospheric constituents such as CO2 and SO2. When the filters are used as windows for gas absorption cells or gas filters, or when they define the instrumental bandwidth by themselves. The effects of mechanical degradation by thermal cycling and/or dust may cause a dramatic impact.

Delaboudiniere, J. P.↗
NASA NTRS1989

Multi-spacecraft testing of time-dependent interplanetary MHD models for operational forecasting of geomagnetic storms

An MHD 2-1/2D, time-dependent model is used, together with observations of six solar flares during February 3-7, 1986, to demonstrate global, large-scale, compound disturbances in the solar wind over a wide range of heliolongitudes. This scenario is one that is likely to occur many times during the cruise, possibly even encounter, phases of the Multi-Comet Mission. It is suggested that a model such as this one should be tested with multi-spacecraft data (such as the MCM and earth-based probes) with several goals in view: (1) utility of the model for operational real-time forecasting of geomagnetic storms, and (2) scientific interpretation of certain forms of cometary activities and their possible association with solar-generated activity.

Dryer, M.↗