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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 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Data Validation Package August 2015 Groundwater and Surface Water Sampling at the Tuba City, Arizona, Disposal Site November 2015

The groundwater compliance strategy for the Tuba City, Arizona, Disposal Site is defined in the 1999 Phase I Ground Water Compliance Action Plan for the Tuba City, Arizona, UMTRA Site. Samples are collected and analyzed on a semiannual basis to evaluate the performance of the Phase I remediation system. Sampling and analyses were conducted as specified in Sampling and Analysis Plan for U.S. Department of Energy Office of Legacy Management Sites (LMS/PRO/S04351, continually updated). U.S. Environmental Protection Agency (EPA) groundwater standards were exceeded in samples collected from monitoring wells and extraction wells as listed in Table 1. The data from this sampling event are generally consistent with previously obtained values and are acceptable for general use as qualified. Data anomalies are not significant with respect to the known nature and extent of contamination and progress of remedial action at the site. The data from this sampling event will be incorporated into the annual performance evaluation report that will present a comprehensive hydrologic summary and evaluation of groundwater remedial action performance at the Tuba City site through March 2016.

2015 Tuba City, AZ Groundwater and Surface Water S↗
DOE OSTI2015

Data Validation Package - June 2015 Groundwater and Surface Water Sampling at the Green River, Utah, Disposal Site

Groundwater samples were collected during the 2015 sampling event from point-of-compliance (POC) wells 0171, 0173, 0176, 0179, 0181, and 0813 to monitor the disposition of contaminants in the middle sandstone unit of the Cedar Mountain Formation. Groundwater samples also were collected from alluvium monitoring wells 0188, 0189, 0192, 0194, and 0707, and basal sandstone monitoring wells 0182, 0184, 0185, and 0588 as a best management practice. Surface locations 0846 and 0847 were sampled to monitor for degradation of water quality in the backwater area of Brown’s Wash and in the Green River immediately downstream of Brown’s Wash. The Green River location 0801 is upstream from the site and is sampled to determine background-threshold values (BTVs). Sampling and analyses were conducted as specified in Sampling and Analysis Plan for U.S. Department of Energy Office of Legacy Management Sites (LMS/PRO/S04351, continually updated, http://energy.gov/lm/downloads/sampling-and- analysis-plan-us-department-energy-office-legacy-management-sites). Water levels were measured at each sampled well. The analytical data and associated qualifiers can be viewed in environmental database reports and are also available for viewing with dynamic mapping via the GEMS (Geospatial Environmental Mapping System) website at http://gems.lm.doe.gov/#. All six POC wells are completed in the middle sandstone unit of the Cedar Mountain Formation and are monitored to measure contaminant concentrations for comparison to proposed alternate concentration limits (ACLs), as provided in Table 1. Contaminant concentrations in the POC wells remain below their respective ACLs.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS2006

Titan Orbiter with Aerorover Mission (TOAM)

We propose to develop a new mission to Titan called Titan Orbiter with Aerorover Mission (TOAM). This mission is motivated by the recent discoveries of Titan, its atmosphere and its surface by the Huygens Probe, and a combination of in situ, remote sensing and radar mapping measurements of Titan by the Cassini orbiter. Titan is a body for which Astrobiology (i.e., prebiotic chemistry) will be the primary science goal of any future missions to it. TOAM is planned to use an orbiter and balloon technology (i.e., aerorover). Aerobraking will be used to put payload into orbit around Titan. The Aerorover will probably use a hot air balloon concept using the waste heat from the MMRTG approx. 500 watts. Orbiter support for the Aerorover is unique to our approach for Titan. Our strategy to use an orbiter is contrary to some studies using just a single probe with balloon. Autonomous operation and navigation of the Aerorover around Titan will be required, which will include descent near to the surface to collect surface samples for analysis (i.e., touch and go technique). The orbiter can provide both relay station and GPS roles for the Aerorover. The Aerorover will have all the instruments needed to sample Titan's atmosphere, surface, possible methane lakes-rivers, use multi-spectral imagers for surface reconnaissance; to take close up surface images; take core samples and deploy seismometers during landing phase. Both active and passive broadband remote sensing techniques will be used for surface topography, winds and composition measurements.

Sittler, Edward C.↗
NASA NTRS2007

Titan Orbiter with Aerorover Mission (TOAM)

We propose to develop a new mission to Titan called Titan Orbiter with Aerorover Mission (TOAM). This mission is motivated by the recent discoveries of Titan, its atmosphere and its surface by the Huygens Probe, and a combination of in situ, remote sensing and radar mapping measurements of Titan by the Cassini orbiter. Titan is a body for which Astrobiology (i.e., prebiotic chemistry) will be the primary science goal of any future missions to it. TOAM is planned to use an orbiter and balloon technology (i.e., aerorover). Aerobraking will be used to put payload into orbit around Titan. One could also use aerobraking to put spacecraft into orbit around Saturn first for an Enceladus phase of the mission and then later use aerocapture to put spacecraft into orbit around Titan. The Aerorover will probably use a hot air balloon concept using the waste heat from the MMRTG approx. 1000 watts. Orbiter support for the Aerorover is unique to our approach for Titan. Our strategy to use an orbiter is contrary to some studies using just a single probe with balloon. Autonomous operation and navigation of the Aerorover around Titan will be required, which will include descent near to the surface to collect surface samples for analysis (i.e., touch and go technique). The orbiter can provide both relay station and GPS roles for the Aerorover. The Aerorover will have all the instruments needed to sample Titan's atmosphere, surface, possible methane lakes-rivers, use multi-spectral imagers for surface reconnaissance; to take close up surface images; take core samples and deploy seismometers during landing phase. Both active and passive broadband remote sensing techniques will be used for surface topography, winds and composition measurements.

Sittler, E. C., Jr.↗
DOE OSTI2019

Surface Erosion of Plasma-Facing Materials Using an Electrothermal Plasma Source and Ion Beam Micro-Trenches

Erosion characteristics of tungsten-alternative plasma-facing materials (PFMs) were tested under high heat flux conditions in the electrothermal plasma source facility at Oak Ridge National Laboratory. The PFMs of interest are high-purity β-3C chemical vapor deposition silicon carbide (SiC) and the MAX phases Ti 3 SiC 2 and Ti 2 AlC [MAX = chemical formula M n+1 AX n , where M is an early transition metal (such as Ti or Ta), A is an A-group element (such as Si or Al), and X is carbon or nitrogen]. Additionally, an erosion analysis method was developed using a combination of focused ion beam microscopy and scanning electron microscopy, carving micro-trench geometries into polished sample surfaces. Samples of SiC, Ti 3 SiC 2 , and Ti 2 AlC were exposed to the electrothermal plasma source alongside tungsten and monocrystalline silicon. Samples were exposed to a Lexan polycarbonate (C 16 H 14 O 3 ) electrothermal plasma stream in a He environment, at a specified impact angle, with infrared camera diagnostics. Edge localized mode–relevant heat fluxes of 0.9 to 1 GW/m 2 over 1-ms discharges were generated on the target surfaces. Tungsten samples exhibited pronounced melt-layer formation and deformation, with measured molten pits 2 to 10 μm in diameter and melt-layer depths of up to 7 μm deep. Surface erosion rates for Ti 3 SiC 2 and Ti 2 AlC ranged from 80 to 775 μm/s and 85 to 470 μm/s, respectively. Both MAX phases exhibited extreme surface fracture and material ejection, with damage depths past 4 μm for Ti 2 AlC and 11 μm for Ti 3 SiC 2 . Lastly, SiC displayed the best performance, in one case surviving 15 consecutive electrothermal plasma exposures with an average erosion rate of about 29 μm/s and no surface fracturing. SiC erosion rates ranged from 23 to 128 μm/s.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Corrosion Behavior of Sm{sub y}(Fe{sub x}Ni{sub 1−x}){sub 4}Sb{sub 12} (0.40 ≤ x ≤ 0.80) in NaCl Solutions Studied by Electron Microscopy and ICP-AES

Filled skutterudites are currently studied as thermoelectric materials to be used in the automotive and nautical field; the study of their resistance to a saline environment is therefore mandatory. To this purpose, the corrosion behavior of several compositions belonging to the Sm{sub y}(Fe{sub x}Ni{sub 1−x}){sub 4}Sb{sub 12} skutterudites system was investigated by immersing samples in differently concentrated (0.1 and 0.5 M) NaCl solutions. The effect of the treatment was analyzed both by SEM–EDS on the sample surface and at fixed times by ICP-AES on the solution. The formation of an oxide layer was observed on the surface of all the samples: the film results uniformly grown on specimens treated in NaCl at the lower concentration, while it is cracked and not spread over the whole surface in the other samples. Relying on the oxide layer thickness, the oxidation resistance results to increase with increasing the Fe content; correspondingly, the Sb concentration in the more diluted solution decreases at each time considered with increasing the Fe amount, pointing at a strict correlation between the cationic release and the oxide formation, and suggesting a possible mechanism for the growth of the protective film.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Elemental and isotopic analysis of inorganic salts by laser desorption ionization mass spectrometry

Laser desorption ionization mass spectrometry is applied for the analysis of elements as well as their isotopic composition in different inorganic salts. At very low laser energies the inorganic ions are desorbed and ionized from the thin layer of the sample surface. The naturally occurring isotopes of alkali and silver ions are resolved using time of flight mass spectrometer. Further increase in laser energy shows the appearance of Al, Cr, and Fe ions in the mass spectra. This indicates the penetration laser beam beyond the sample surface leading to the ablation of sample target at higher energies. The simultaneous appearance of atomic ions from the sample target at relatively higher laser energies hampers the unambiguous identification of amino acid residues from the biomolecular ions in MALDI-MS.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2011

Surface characterization based on optical phase shifting interferometry

Apparatus, techniques and systems for implementing an optical interferometer to measure surfaces, including mapping of instantaneous curvature or in-plane and out-of-plane displacement field gradients of a sample surface based on obtaining and processing four optical interferograms from a common optical reflected beam from the sample surface that are relatively separated in phase by .pi./2.

47 OTHER INSTRUMENTATION↗
DOE OSTI2013

Local triboelectrification of an n-GaAs surface using the tip of an atomic-force microscope

The method of scanning Kelvin-probe microscopy is used to show that the effect of triboelectrification is observed when the tip of an atomic-force microscope interacts with the surface of n-GaAs epitaxial layers. The sign of the change in the potential indicates that the sample surface after triboelectrification becomes more negative. The observed specific features of the phenomena can be attributed to the thermally activated generation of point defects in the vicinity of the sample surface due to deformation caused by the tip.

36 MATERIALS SCIENCE↗
NASA NTRS2000

Potential Challenges in Near-Field Scanning Optical Microscopy for Space Applications

Near-field scanning optical microscopy (NSOM) also called scanning near-field optical microscopy (SNOM) is now well accepted as a powerful tool for sub-wavelength (nanoscale in the optical region) spatial resolution microscopy and a large number of related tasks. The importance lies in the fact of strategic advantages of standard microscopy but with significantly enhanced resolution. Since many modern optical diagnostic techniques have found useful applications in space, it is logical to consider the future role of NSOM in such situations. For example, protein crystal growth study under microgravity conditions is a valid candidate. If applied successfully, processes at molecular level can be studied during the growth. NSOM has already been demonstrated to be useful for the study of such crystals here on earth. The basic principle of NSOM can be illustrated. The illumination-collection mode is shown although several other possible approaches exist. In this, the sample is illuminated and the light from the sample is collected through the same tiny aperture opening. A tapered optical fiber is scanned near the sample surface. The tip is coated generally with a metal with a sub-wavelength aperture opening. The tip-sample distance is maintained constant while scanning. Thus, the optical signal available for collection is generally a function of the optical properties of the sample surface. Since the aperture is sub-wavelength in diameter and the tip is held very close (again in the sub-wavelength domain) to the surface, the lateral resolution in the sub-wavelength domain is obtained. Thus, the typical wavelength- order resolution of ordinary microscopy can be significantly enhanced while maintaining the strategic advantages (no need of sample in vacuum chamber, electron beams, etc). Commercial NSOM systems play a key role in the success and widespread acceptance of the tool. These commercial systems work fairly well in laboratory conditions on earth. However, they may not be deployed on a space mission as such with comparable outcome. In this communication we discuss several potential problems and some possible solutions.

Vikram, Chandra S.↗
DOE OSTI2024

High efficiency active environmental sampling of chemical traces

A method of sample collection includes collecting an analyte from a sampling surface using a rapidly curable liquid gel comprising one or more metal particles; co-aggregating the one or more metal particles from the rapidly curable liquid gel and the analyte from the sampling surface; and rapidly curing the rapidly curable liquid gel. The composition and sample preparation conditions may facilitate improved collection efficiency of analytes during environmental and forensic evidence sampling. In addition, the composition and sample preparation conditions may facilitate enhanced detection and identification of the analyte using e.g., Surface Enhanced Raman Spectrometry (SERS).

Junghans, Ann↗
DOE OSTI2021

Suppression of the vacuum space-charge effect in fs-photoemission by a retarding electrostatic front lens

The performance of time-resolved photoemission experiments at fs-pulsed photon sources is ultimately limited by the e–e Coulomb interaction, downgrading energy and momentum resolution. Here, we present an approach to effectively suppress space-charge artifacts in momentum microscopes and photoemission microscopes. A retarding electrostatic field generated by a special objective lens repels slow electrons, retaining the k-image of the fast photoelectrons. The suppression of space-charge effects scales with the ratio of the photoelectron velocities of fast and slow electrons. Fields in the range from -20 to 01100 V/mm for E kin = 100 eV to 4 keV direct secondaries and pump-induced slow electrons back to the sample surface. Ray tracing simulations reveal that this happens within the first 40 to 3 μm above the sample surface for E kin = 100 eV to 4 keV. An optimized front-lens design allows switching between the conventional accelerating and the new retarding mode. Time-resolved experiments at E kin = 107 eV using fs extreme ultraviolet probe pulses from the free-electron laser FLASH reveal that the width of the Fermi edge increases by just 30 meV at an incident pump fluence of 22 mJ/cm2 (retarding field -21 V/mm). For an accelerating field of +2 kV/mm and a pump fluence of only 5 mJ/cm 2 , it increases by 0.5 eV (pump wavelength 1030 nm). At the given conditions, the suppression mode permits increasing the slow-electron yield by three to four orders of magnitude. The feasibility of the method at high energies is demonstrated without a pump beam at E kin = 3830 eV using hard x rays from the storage ring PETRA III. The approach opens up a previously inaccessible regime of pump fluences for photoemission experiments.

47 OTHER INSTRUMENTATION↗
DOE OSTI2016

Analysis of Tank 38H (HTF-38-16-26, 27) and Tank 43H (HTF-43-16-28, 29) Samples for Support of the Enrichment Control and Corrosion Control Programs

Savannah River National Laboratory analyzed samples from Tank 38H and Tank 43H to support Enrichment Control Program and Corrosion Control Program. The total uranium in the Tank 38H samples ranged from 20.5 to 34.0 mg/L while the Tank 43H samples ranged from 47.6 to 50.6 mg/L. The U-235 percentage ranged from 0.62% to 0.64% over the four samples. The total uranium and percent U-235 results appear consistent with previous Tank 38H and Tank 43H uranium measurements. The Tank 38H plutonium results show a large difference between the surface and sub-surface sample concentrations and a somewhat higher concentration than previous sub-surface samples. The two Tank 43H samples show similar plutonium concentrations and are within the range of values measured on previous samples. The plutonium results may be biased high due to the presence of plutonium contamination in the blank samples from the cell sample preparations. The four samples analyzed show silicon concentrations ranging from 47.9 to 105 mg/L.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2014

Nano-Scale Fission Product Phases in an Irradiated U-7Mo Alloy Nuclear Fuel

Irradiated nuclear fuel is a very difficult material to characterize. Due to the large radiation fields associated with these materials, they are hard to handle and typically have to be contained in large hot cells. Even the equipment used for performing characterization is housed in hot cells or shielded glove boxes. The result is not only a limitation in the techniques that can be employed for characterization, but also a limitation in the size of features that can be resolved The most standard characterization techniques include light optical metallography (WM), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). These techniques are applied to samples that are typically prepared using grinding and polishing approaches that will always generate some mechanical damage on the sample surface. As a result, when performing SEM analysis, for example, the analysis is limited by the quality of the sample surface that can be prepared. However, a new approach for characterizing irradiated nuclear fuel has recently been developed at the Idaho National Laboratory (INL) in Idaho Falls, Idaho. It allows for a dramatic improvement in the quality of characterization that can be performed when using an instrument like an SEM. This new approach uses a dual-beam scanning microscope, where one of the beams isa focused ion beam (FIB), which can be used to generate specimens of irradiated fuel (-10µm x 10µm) for microstructural characterization, and the other beam is the electron beam of an SEM. One significant benefit of this approach is that the specimen surface being characterized has received much less damage (and smearing) than is caused by the more traditional approaches, which enables the imaging of nanometer­ sized microstructural features in the SEM. The process details are for an irradiated low-enriched uranium (LEU) U-Mo alloy fuel Another type of irradiated fuel that has been characterized using this technique is a mixed oxide fuel.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2016

Thermoacoustic and thermoreflectance imaging of biased integrated circuits: Voltage and temperature maps

In this work a combined thermoacoustic and thermoreflectance set-up was designed for imaging biased microelectronic circuits. In particular, it was used with polycrystalline silicon resistive tracks grown on a monocrystalline Si substrate mounted on a test chip. Thermoreflectance images, obtained by scanning a probe laser beam on the sample surface, clearly show the regions periodically heated by Joule effect, which are associated to the electric current distribution in the circuit. The thermoacoustic signal, detected by a pyroelectric/piezoelectric sensor beneath the chip, also discloses the Joule contribution of the whole sample. However, additional information emerges when a non-modulated laser beam is focused on the sample surface in a raster scan mode allowing imaging of the sample. The distribution of this supplementary signal is related to the voltage distribution along the circuit.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Uniform deposition of size-selected clusters using Lissajous scanning

Size-selected clusters can be deposited on the surface using size-selected cluster ion beams. However, because of the cross-sectional intensity distribution of the ion beam, it is difficult to define the coverage of the deposited clusters. The aggregation probability of the cluster depends on coverage, whereas cluster size on the surface depends on the position, despite the size-selected clusters are deposited. It is crucial, therefore, to deposit clusters uniformly on the surface. In this study, size-selected clusters were deposited uniformly on surfaces by scanning the cluster ions in the form of Lissajous pattern. Two sets of deflector electrodes set in orthogonal directions were placed in front of the sample surface. Triangular waves were applied to the electrodes with an irrational frequency ratio to ensure that the ion trajectory filled the sample surface. The advantages of this method are simplicity and low cost of setup compared with raster scanning method. The authors further investigated CO adsorption on size-selected Pt{sub n} (n = 7, 15, 20) clusters uniformly deposited on the Al{sub 2}O{sub 3}/NiAl(110) surface and demonstrated the importance of uniform deposition.

42 ENGINEERING↗
DOE OSTI2014

Thermal transport in shock wave–compressed solids using pulsed laser heating

A pulsed laser heating method was developed for determining thermal transport properties of solids under shock-wave compression. While the solid is compressed, a laser deposits a known amount of heat onto the sample surface, which is held in the shocked state by a transparent window. The heat from the laser briefly elevates the surface temperature and then diffuses into the interior via one-dimensional heat conduction. The thermal effusivity is determined from the time history of the resulting surface temperature pulse, which is recorded with optical pyrometry. Thermal effusivity is the square root of the product of thermal conductivity and volumetric heat capacity and is the key thermal transport parameter for relating the surface temperature to the interior temperature of the sample in a dynamic compression experiment. Therefore, this method provides information that is needed to determine the thermodynamic state of the interior of a compressed metal sample from a temperature measurement at the surface. The laser heat method was successfully demonstrated on tin that was shock compressed with explosives to a stress and temperature of ∼25 GPa and ∼1300 K. In this state, tin was observed to have a thermal effusivity of close to twice its ambient value. The implications on determining the interior shock wave temperature of tin are discussed.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2014

Reliable wet-chemical cleaning of natively oxidized high-efficiency Cu(In,Ga)Se{sub 2} thin-film solar cell absorbers

Currently, Cu-containing chalcopyrite-based solar cells provide the highest conversion efficiencies among all thin-film photovoltaic (PV) technologies. They have reached efficiency values above 20%, the same performance level as multi-crystalline silicon-wafer technology that dominates the commercial PV market. Chalcopyrite thin-film heterostructures consist of a layer stack with a variety of interfaces between different materials. It is the chalcopyrite/buffer region (forming the p-n junction), which is of crucial importance and therefore frequently investigated using surface and interface science tools, such as photoelectron spectroscopy and scanning probe microscopy. To ensure comparability and validity of the results, a general preparation guide for “realistic” surfaces of polycrystalline chalcopyrite thin films is highly desirable. We present results on wet-chemical cleaning procedures of polycrystalline Cu(In{sub 1-x}Ga{sub x})Se{sub 2} thin films with an average x = [Ga]/([In] + [Ga]) = 0.29, which were exposed to ambient conditions for different times. The hence natively oxidized sample surfaces were etched in KCN- or NH{sub 3}-based aqueous solutions. By x-ray photoelectron spectroscopy, we find that the KCN treatment results in a chemical surface structure which is – apart from a slight change in surface composition – identical to a pristine as-received sample surface. Additionally, we discover a different oxidation behavior of In and Ga, in agreement with thermodynamic reference data, and we find indications for the segregation and removal of copper selenide surface phases from the polycrystalline material.

14 SOLAR ENERGY↗