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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
DOE OSTI2025

Angularly resolved spectral reconstruction of x rays via filter pack attenuation

We have designed a new filter pack array to measure angular variations in x-ray spectra during a single shot. The filter pack was composed of repeating identical columns of aluminum and copper filters of varying thicknesses. These columns were located at different positions to measure the spectrum at each corresponding angle. This array was utilized in an experiment to measure the energy evolution of betatron x rays in a laser wakefield accelerator by curving the wakefield with a transverse density gradient, streaking the x rays across the array in front of an x-ray charge-coupled device (CCD) camera. After subtracting the background and “flattening” the image to remove spatial nonuniformities, a critical energy was calculated for each position that produced the best agreement with the measured signal. There was a clear change in critical energy with angle, shedding light on the dynamics of the electrons that traveled through the accelerator. Furthermore, these angles correspond to distinct emission times, covering a timescale of tens of picoseconds. The filter pack was capable of recovering these angular details without the impact of errors introduced by shot-to-shot variability.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1985

Surface hardening of steel by boriding in a cold rf plasma

Scanning electron spectroscopy, X-ray diffractometry, Auger electron spectroscopy, and microhardness measurements, are used to study the surfaces of 4340-steel samples that have been borided in a cold RF plasma which had been initiated in a gas mixture of 2.7 percent diborane in Ar. As a result of the dislocation of the diborane in the plasma, boron is deposited on the surface of the steel substrate and two crystalline phases, tetragonal Fe2B and orthorhombic FeB, are formed. The formation of boride phases then increases the surface microhardness from 2650 MPa to a maximum value of 7740 MPa.

Finberg, I.↗
NASA NTRS2018

Forming Perchlorates on Mars Through Plasma Chemistry During Dust Events

We report experimental evidences to support a new formation mechanism, multiphase redox plasma chemistry, for perchlorate on Mars observed during the Phoenix mission, whose high concentrations and high ClO4/Cl ratio cannot be fully interpreted by photochemistry. This chemical reaction occurs between Cl-bearing minerals on the Mars surface and free radicals generated by electrostatic discharge (ESD) during Mars dust events (dust storms, dust devils, and grain saltation). We conducted simulated ESD experiments in a Mars chamber with pure CO2, CO2+H2O(g), and Mars Simulate Gas Mixture at Martian atmospheric pressure. We directly observed (1) the instantaneous generation of atmospheric free radicals CO2+, CO+, OI, HIII, HII, OH, ArI, N2, and N2+in normal glow discharge (NGD), detected by in situ plasma emission spectroscopy, and O3by UV and Mid-IR spectroscopy; (2) the fast transformation of NaCl to NaClO3and NaClO4detected by laser Raman spectroscopy, with oxychlorine enrichment at the sample surfaces confirmed by ion chromatography. Through two sets of experimental comparison, we found that the oxidation power of ESD-electron is three orders of magnitude higher than that of UVC-photon. We scaled our experimental results to the modeled ESD in Mars dust events and Mars surface UV radiation level, and concluded that plasma chemistry occurred during Mars dust events can be an additional important formation mechanism for the large amounts of perchlorates observed during various missions to Mars.

Wu, Zhongchen↗
DOE OSTI2024

Filterscope Techniques for Parasitic Signal Screening

Here, the filterscope diagnostic uses bandpass filters and photomultiplier tubes (PMTs) to detect specific spectral emission lines. A filterscope was used to measure the W I 400.88 nm line emission as a function of ion energy on the Radio Frequency Plasma Interaction Experiment (RF PIE) for the purpose of assessing W erosion on plasma-facing components (PFCs). Different filter techniques are being explored and compared in order to effectively screen out nearby impurity lines, like the Ar II 401.39 nm line. The effectiveness of these techniques is determined by comparing the measurements to a high-resolution 1.0 m Czerny–Turner spectrometer with 0.012 nm spectral resolution. The ability to filter out nearby impurity emissions is useful when imaging PFCs in fusion devices including divertor and antenna guard limiters. Initial results with a helium plasma show little difference between the two techniques at higher bias voltages. In a helium plasma at lower dc bias voltages, a two-filter technique with filters at two separate wavelengths was shown to be more effective at screening out background signals. Data collected with an argon plasma however show the technique with overlapping filters on the line of interest is a closer match to spectrometer data at lower dc bias voltages.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2025

Development and characterization of an aerosol-generated multi-method analytical particle test material

Ceria (CeO 2 ) particles with low to ultra-low loading of nickel dopant were produced using an aerosol-based, droplet-to-particle synthesis via an in-line calcination technique. This aerosol-based synthesis method enables the production of particles with a monodisperse size distribution. These produced and well-characterized, multi-element, ceria-based particles demonstrate a material exemplar for multi-method analytical testing. They were prepared from a cerium nitrate feedstock where low loading nickel dopant was added at target Ni/(Ni + Ce) atomic percents of 1 %, 0.1 %, and 0.01 %, using a nickel nitrate spike. This methodology proved to produce ceria particles doped with a dynamic range of low to ultra-low loadings of nickel over a 24-h period, with consistent size distribution, morphology, and composition. The successful incorporation of nickel was demonstrated with bulk and single particle inductively coupled plasma mass spectroscopy and revealed notable particle-to-particle elemental homogeneity. X-ray photoelectron spectroscopy demonstrated the presence of a high concentration of nickel dopant incorporated preferentially toward the surface of the particles, and that this dopant aided oxidation of surface Ce(III) atoms to Ce(IV). These particle test materials were then validated through X-ray absorption near edge spectroscopy, comparing the ultra-low 0.01 % Ni and low 1 % Ni-doped ceria samples. This revealed a more-reduced oxidation state of the nickel with an increase in dopant concentration. Finally, this work demonstrates a synthesis and systematic characterization scheme to produce multi-method analytical test particulates.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Exploring constituent redistribution in irradiated U-19Pu-14Zr fuel via electron probe microanalysis

Here, the phenomena of constituent redistribution, wherein a previously homogeneous metallic fuel forms discrete, radially concentric compositional zones upon irradiation was investigated by examining an irradiated U-19Pu-14Zr fuel (where numbers represent wt. %) with a burnup of 11.5 at.% with electron probe microanalysis (EPMA) and quadruple inductively coupled plasma mass spectroscopy (Q-ICP-MS). EPMA-generated U, Pu, and Zr compositional data obtained from a diameter traverse of the sample was converted to mass and was used to: 1) compare the overall fuel element analysis results between the two methods, 2) determine the number of compositionally distinct zones forming as a result of constituent redistribution; and 3) quantify the post-irradiation loss or gain of U, Pu, and Zr atoms in each distinct compositional zone. Weight percent concentrations of U, Pu, and Zr for the overall cross section compare favorably between the two analytical methods, suggesting that the spatially resolved EPMA analysis complements bulk chemical analysis. Among the four identified compositional zones, post-irradiation quantification of U, Pu, and Zr elemental atom content changes shows that the quantity of U atoms lost from the innermost zone is slightly less than the quantity of U atoms gained by the middle two zones, and the quantity of Zr atoms lost from the high-U third zone is slightly less than is gained by the two innermost zones. Pu is lost from all four zones, although the innermost zone and the high-U third zone lose a significantly higher percentage (> 22 %) of their initial Pu atoms than the other two zones. For all three elements, EPMA cannot distinguish between atoms lost due to transport to a different zone from atoms lost due to nuclear processes; however, the insight gained from using this process can be used to experiment with new modeling techniques to predict constituent redistribution in U-Pu-Zr fuels.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2025

Statistical fracture behavior of doped UO 2 using a ball-on-ring equibiaxial flexure test method

Metal oxide dopants, such as titanium and chromium oxides, have garnered considerable attention for their potential to increase grain size (≥ 30 µm) in UO 2 fuel, purportedly enhancing fission gas retention during reactor operation. Fuel performance is significantly impacted by fuel fracture behavior, so it is important to understand the effects of enhanced grain size and dopant content on UO 2 fuel fracture. UO 2 pellets were doped with 0.1 wt% TiO 2 and 0.3 wt% Cr 2 O 3 to alter density and grain size. Inductively coupled plasma mass spectroscopy measured dopant levels pre- and post-sintering. X-ray diffraction revealed lattice changes and microstrain via Rietveld refinement. Field emission scanning electron microscopy determined grain sizes of approximately 30 µm for TiO 2 doping and 7 µm for Cr 2 O 3 doping. Transverse rupture strength tests were performed on over 30 samples per dataset to obtain characteristic strength and Weibull modulus. Results indicate no statistical difference in fracture strength between 0.1 wt% TiO 2 doped UO 2 and undoped UO 2 , while 0.3 wt% Cr 2 O 3 doped UO 2 exhibited a 20% decrease in fracture strength. Doped UO 2 samples also showed reduced Weibull modulus compared to undoped UO 2 , suggesting increased scatter in fracture strength. This study's findings suggest that titanium and chromium oxide doping in UO 2 , regardless of grain size, induce residual stresses, decreasing fracture strength and increasing variability in fracture behavior.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2025

A fully ro-vibrationally resolved corona model for the molecular hydrogen Fulcher-𝛼 system

A ro-vibrationally resolved corona model for the molecular hydrogen Fulcher-𝛼 transition based on the Yacora solver is introduced. The model couples 1365 ro-vibrational levels of the 𝑋 1 ⁢𝛴$^+_𝑔$, 𝑑 3⁢ 𝛱 𝑢 and 𝑎 3 ⁢𝛴$^+_𝑔$ states via electron impact excitation from the ground state into the 𝑑 3⁢ 𝛱 𝑢 state and subsequent spontaneous emission into the 𝑎 3 ⁢𝛴$+_𝑔$ state. For the process of electron impact excitation a set of 45260 fully ro-vibrationally resolved cross sections calculated with the molecular convergent close-coupling (MCCC) method in the adiabatic-nuclei formulation is applied. The MCCC cross sections are compared with results of a scaling method used in other works, demonstrating the need for dedicated ro-vibrationally resolved cross sections. By post-processing the model output, entire Fulcher spectra can be simulated. These spectra are benchmarked with measurements from an inductively coupled plasma discharge at a pressure between 1.1–10 Pa and a RF power of 700 W. The model results agree very well with the experiment both in relative shape and in absolute value. A non-ro-vibrationally resolved, purely electronically resolved collisional radiative model for molecular hydrogen (including further states and reaction channels) is applied to investigate the validity of the corona approximation for the benchmark plasmas and the relevance of possible process extensions of the corona model. Furthermore, the influence of collisional quenching, autoionization and predissociation is discussed.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2025

Variations in GARS powder microstructure as a function of powder chemistry and particle size

The properties of metal produced through powder metallurgy depends on the feedstock used. Powders produced via gas atomization reaction synthesis (GARS) are used to produce oxide dispersion strengthened alloys. The desired powder size range can vary for each consolidation technique. However, powder microstructure also can vary with powder particle size, which in turn can impact the microstructure and properties of the consolidated parts. In this study, GARS powders are characterized via inductively coupled plasma mass spectroscopy, inert gas fusion, and high-resolution x-ray diffraction to determine variations in elemental and phase compositions. Transmission electron microscopy was used to understand microstructure variations as a function of chemistry and size. Across the three batches tested intermetallic content was 0.73–1.35 wt% in the 0-20 μm powder batch and increased to 2.46–3.80 wt% in the coarse 45-106 μm batch. Across all batches, volume percent of surface oxidation decreased with powder diameter, with volume percents within the range of 0.75–1.2 % across 10 μm powder particles, and below 0.4 % across coarse powder particles approximately 100 μm in diameter. These observations were supported by inert gas fusion measurements. However, the oxide layer was thicker in coarse powder particles due to a slower cooling rate. Increasing oxygen content in atomization gas to 2000 ppm and adding yttrium increased both the surface oxidation content and yttrium intermetallic content. Lastly, intermetallic phases within the powder coarsened with powder size. Intermetallic morphology changed from fine spherical intermetallic and columnar dendritic growth to a cellular structure with finer spherical intermetallic, to coarse irregular intermetallic and intermetallic along grain boundaries as a result of slower cooling rate and solidification rate in coarse powder particles. Furthermore, the addition of zirconium does not appear to significantly change intermetallic morphology, but the composition changed from a Y-Fe rich intermetallic to a Y-Zr-Fe intermetallic.

42 ENGINEERING↗
DOE OSTI2025

Impact of ultrafast laser pulse repetition rate on filament acoustic and emission signatures

Femtosecond filaments formed at standoff distances can be used for interrogating various types of matter, making them of potential interest for remote sensing. However, the physical aspects of the filaments generated at standoff distances are influenced by various environmental and laser properties, including the repetition rate of the laser. In this study, we evaluate the role of the predecessor pulse on the properties of filaments by varying the repetition rate of the laser in the range of 10–1000 Hz and using acoustic and emission signatures to diagnose filament properties. Our results show that filaments are brighter at high repetition rates while they are elongated at low repetition rates. The repetition rate has minimal influence on the downstream edge of the filament generation, while the upstream edge becomes elongated. The shadowgram images showed that the turbulence generated by the predecessor pulse may influence the next pulse when the laser is operating at high repetition rates.

47 OTHER INSTRUMENTATION↗
DOE OSTI2025

Revealing the Structure and Dynamics of Self-Generated Electric and Magnetic Fields Near Plasma Stagnation in Laser-Driven Hohlraums

By coupling newly developed triparticle charged particle radiography with radiography reconstruction algorithms and novel reconstruction postprocessing techniques, the spatial structure and time evolution of self-generated electric and magnetic fields in laser-driven vacuum hohlraums have been quantitatively revealed. Through high-fidelity data from a series of experiments, it is shown that late in the hohlraum evolution (after the end of laser drive) these fields are strongly correlated in both space and time, providing evidence that their evolution is primarily dominated by advection with the plasma flow. At these late times, plasma flow velocities inferred from both gross radiography analysis and field reconstructions (and corroborated with Thomson scattering measurements) indicate that the plasma is approaching stagnation near the hohlraum axis. Finally, these experiments provide not only new physical insight into spontaneously generated hohlraum fields, but also provide important spatially and temporally resolved information for future benchmarking of numerical codes.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2024

Synthesis of Zeolites LiX and LiAgX

In this work, we produced approximately 50 grams of zeolite LiX and 50 grams of zeolite LiAgX from commercially available zeolite X. The production of the two specialized zeolite phases was accomplished via a series of ion exchange steps followed by washing, drying, and calcining to produce the final materials. The ion exchange was confirmed by several methods including inductively-coupled plasma emission spectroscopy of exchange solution aliquots, gravimetric analysis, energy dispersive x-ray spectroscopy, and X-ray diffraction. We synthesized approximately 115 grams of zeolite LiX in a large-scale production step after completing a proof-of-concept experiment demonstrating the methodology. The production of zeolite LiX from zeolite X yielded an ion exchange (Li + →Na + ) of approximately 82%. The production of zeolite LiAgX from the previously synthesized zeolite LiX was targeted to exchange approximately 20% of the Li + ions with Ag + ions. We first performed a proof-of-concept experiment demonstrating the reaction pathway and selectivity of the Ag + ion, and then performed a large-scale synthesis of zeolite LiAgX using approximately 50 grams of the zeolite LiX. Our final exchange percentage of silver into the zeolite LiX matrix was approximately 20.8%.

36 MATERIALS SCIENCE↗
NASA NTRS1979

Common-cavity pumped laser

Two lasers linked by dichroic coupler are packaged in single cavity. Resulting system is more compact, efficient, and durable than conventional two-cavity lasers. Such instruments (portable pumped lasers) are needed for spectroscopy in plasma diagnostics in atmospheric research, and in radar-like devices for seeing through dense fog or smoke.

Koepf, G. A.↗
NASA NTRS1981

To Produce Nutrients for Plant Growth

On July 1, 1979 a new research program entitled "Development of a Prototype Experiment for Treating CELSS and PCELSS Wastes to Produce Nutrients for Plant Growth" was undertaken by the Massachusetts Institute of Technology and the Georgia Institute of Technology under grant from the National Aeronautics and Space Administration's Ames Research Center. The program was designed to be completed over a five-year period, with the work divided into two phases. Phase I covers approximately two years and involves the development of necessary facilities, chemical methodologies and models to allow meaningful experiments during Phase II, which will involve interfacing waste oxidation with plant growth. Homogeneous samples of freeze-dried human feces and urine have been prepared to assure comparability of results among various CELSS waste treatment research groups. A model of food processing wastes within a PCELSS was developed, and an initial batch of waste was prepared. An automated gas chromatographic system to analyze oxidizer effluents was designed and is operational. A state-of-the-art quantitative elemental analysis capability, built around inductively coupled plasma emission spectroscopy and atomic absorption spectroscopy using electrothermal atomization, has been demonstrated. A continuous flow wet oxidation system was constructed and is now operational.

Michael Modell↗
NASA NTRS1990

Tunable Quantum-Well Submillimeter-Wave Oscillators

Tunable submillimeter-wave generator is layered (AI/Ga)As device. Frequencies adjusted via applied voltages. New device concept offers potential to make relatively compact, efficient local oscillators for heterodyne mixers in submillimeter radar and imaging systems, nondestructive testing, diagnosis of plasmas, airborne spectroscopy of atmosphere, detection of weapons and other contraband, and communications.

Maserjian, Joseph↗