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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 1,243 records · Page 69
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Corrosion-resistant multilayer structures with improved reflectivity

In one general embodiment, a thin film structure includes a substrate; a first corrosion barrier layer above the substrate; a reflective layer above the first corrosion barrier layer, wherein the reflective layer comprises at least one repeating set of sub-layers, wherein one of the sub-layers of each set of sub-layers being of a corrodible material; and a second corrosion barrier layer above the reflective layer. In another general embodiment, a system includes an optical element having a thin film structure as recited above; and an image capture or spectrometer device. In a further general embodiment, a laser according to one embodiment includes a light source and the thin film structure as recited above.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Fault Imaging with High-Resolution Seismic Reflection for Earthquake Hazard and Geothermal Resource Assessment in Reno, Nevada

The Truckee Meadows basin is situated adjacent to the Sierra Nevada microplate, on the western boundary of the Walker Lane. Being in the transition zone between a range-front normal fault on the west and northwest-striking right-lateral strike slip faults to the east, there is no absence of faulting in this basin. The Reno- Sparks metropolitan area is located in this basin, and with a signi cant population living here, it is important to know where these faults are. High-resolution seismic reflection surveys are used for the imaging of these faults along the Truckee River, across which only one fault was previously mapped, and in southern Reno near and along Manzanita Lane, where a swarm of short faults has been mapped. The reflection profiles constrain the geometries of these faults, and suggest additional faults not seen before. Used in conjunction with depth to bedrock calculations and gravity measurements, the seismic reflection surveys provide de nitive locations of faults, as well as their orientations. O sets on these faults indicate how active they are, and this in turn has implications for seismic hazard in the area. In addition to seismic hazard, the faults imaged here tell us something about the conduits for geothermal fluid resources in Reno.

15 GEOTHERMAL ENERGY↗
DOE OSTI2015

Results of Partially-Reflected Critical Experiments in Square-Pitched Arrays of Water-Moderated 6.9 Percent Enriched Fuel Rods

The Seven Percent Critical Experiment (7uPCX) was designed to provide benchmark criticality and reactor physics data for water-moderated pin-fueled nuclear reactor cores. The enrichment of the fuel was chosen to explore the enrichment range above the current 5% ceiling for US commercial pressurized water reactors. The experiment was part of the US Department of Energy (DOE) Nuclear Energy Research Initiative (NERI) Project 01-124 titled “Reactor Physics and Criticality Benchmark Evaluations for Advanced Nuclear Fuel”. The NERI project was a collaboration between AREVA Federal Services, LLC; the University of Florida; Oak Ridge National Laboratory; and Sandia National Laboratories (SNL). The experiments at Sandia are currently supported by the DOE National Nuclear Security Administration Nuclear Criticality Safety Program. Two sets of benchmark experiments have been completed and documented as LEU-COMP-THERM-080 and LEU-COMP-THERM-078. Those experiments were done with the number of fuel rods in the fully-reflected array as the approach parameter. The experiments reported here are similar to those in LEU-COMP-THERM-080 except that the arrays are partially-reflected – the arrays were larger than would be possible with full reflection and the approach-to-critical experiments were done with the depth of the water in the critical assembly as the approach parameter. These experiments are reported as LEU-COMP-THERM-096.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2016

Analysis-Software for Hyperspectral Algal Reflectance Probes v. 1.0

This software provides onsite analysis of the hyperspectral reflectance data acquired on an outdoor algal pond by a multichannel, fiber-coupled spectroradiometer. The analysis algorithm is based on numerical inversion of a reflectance model, in which the above-water reflectance is expressed as a function of the single backscattering albedo, which is dependent on the backscatter and absorption coefficients of the algal culture, which are in turn related to the algal biomass and pigment optical activity, respectively. Prior to the development of this software, while raw multichannel data were displayed in real time, analysis required a post-processing procedure to extract the relevant parameters. This software provides the capability to track the temporal variation of such culture parameters in real time, as raw data are being acquired, or can be run in a post processing mode. The software allows the user to select between different algal species, incorporate the appropriate calibration data, and observe the quality of the resulting model inversions.

Timlin, Jerilyn A.↗
DOE OSTI2017

Gradient SiNO anti-reflective layers in solar selective coatings

A solar selective coating includes a substrate, a cermet layer having nanoparticles therein deposited on the substrate, and an anti-reflection layer deposited on the cermet layer. The cermet layer and the anti-reflection layer may each be formed of intermediate layers. A method for constructing a solar-selective coating is disclosed and includes preparing a substrate, depositing a cermet layer on the substrate, and depositing an anti-reflection layer on the cermet layer.

Ren, Zhifeng↗
DOE OSTI2017

Reflective article having a sacrificial cathodic layer

The present invention relates to reflective articles, such as solar mirrors, that include a sacrificial cathodic layer. The reflective article, more particularly includes a substrate, such as glass, having a multi-layered coating thereon that includes a lead-free sacrificial cathodic layer. The sacrificial cathodic layer includes at least one transition metal, such as a particulate transition metal, which can be in the form of flakes (e.g., zinc flakes). The sacrificial cathodic layer can include an inorganic matrix formed from one or more organo-titanates. Alternatively, the sacrificial cathodic layer can include an organic polymer matrix (e.g., a crosslinked organic polymer matrix formed from an organic polymer and an aminoplast crosslinking agent). The reflective article also includes an outer organic polymer coating, that can be electrodeposited over the sacrificial cathodic layer.

36 MATERIALS SCIENCE↗
DOE OSTI2017

ATALANTE research facility-implementation of a rule of fractions for the management of reflecting materials in mass-limited units

ATALANTE, a research unit located in Marcoule, is one of the main Nuclear Facilities of the French CEA. As concerns criticality risk prevention, this facility is divided into work units mostly managed through a mass control mode. The authorized limit is 350 g of fissile material with {sup 239}Pu-H{sub 2}O as reference fissile medium. This mass limit was determined considering a reflection by 20 cm of water. Under these conditions, some neutronic reflectors which are more efficient than water can only be authorized in limited quantities. In ATALANTE the reflecting materials identified as requiring a specific form of management are lead, uranium ({sup 235}U/U{sub total} = 1%), graphite, heavy water and beryllium. Initially a maximum permissible mass was determined for each of these materials taken separately. However, this method requires that when different reflectors are present simultaneously, the sum of the masses of all these reflectors must be less than the limit specified for the most penalizing of them. This rule has proved to be too restrictive for the operators. A new rule has therefore been implemented: the rule of fractions. Criticality calculations were performed to demonstrate that this rule is acceptable. The geometric configurations studied involved a sphere of 350 g of {sup 239}Pu moderated by water and reflected by various masses of 2 to 6 reflectors (successions of concentric shells), followed by 20 cm of water. It was concluded that compliance with the new rule makes it possible to ensure criticality safety in the simultaneous presence of different reflectors. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2024

Demonstration and Automation of Reflected Target Optical Measurement for Heliostats

Accurate optical surfaces are a primary driver of concentrated solar power plant performance. Errors in pointing and tracking mirrors, the canting of individual mirror facets, and the surface slope of the mirror itself can be caused by errors during assembly, transportation, wind loading, gravity, and many other sources. The tools that exist to measure these error sources today largely rely on fringe deflectometry (SOFAST, QDec, others), or photogrammetry with targets attached to the mirror surface. Since 2022, NREL has been developing a measurement method called the Reflected Target Non-intrusive Assessment (ReTNA) system. This system differs from most established methods in that we perform deflectometry with a pattern of coded targets, identified in space with photogrammetry. Reflected target systems have several advantages over traditional fringe deflectometry systems. Firstly, they can be operated in bright or ambient lighting, a challenge for fringe systems that use a projector and screen. Reflected target systems also can use a much lighter and less expensive target than projector-based systems. Lastly, 2D slope measurement can be solved from a single image, which leads to several advantages for accommodating faster measurements and smaller sized targets. These advantages make ReTNA particularly well-suited for applications where there are space or lighting constraints, like performing heliostat quality assurance on an assembly line. It's also useful when a lightweight, flexible system is needed, like for heliostat developers to quickly measure a new heliostat design at different orientations, to observe gravitational effects on the mirror surface shape. In the last year, significant improvements were made to this tool to make it more useful for these applications. These improvements were focused around validation of the ReTNA measurement system, and automation of the setup and measurement process. First, we present an improved ReTNA layout, for use on the heliostat assembly line. Next, we detail the various changes to the ReTNA software and computer vision methods to automate data collection in this new setup, and lessons learned from this process. The goal with this new setup is to perform a full heliostat surface characterization without removing the mirror from the assembly line. Lastly, we share results from several ReTNA validation studies undertaken over the last year. These include repeated ReTNA measurement on demonstration mirror facets, comparisons with other optical measurement tools, and some studies aimed at quantifying the uncertainty of ReTNA measurement under various constraints (mirror-target spacing, camera resolution, etc.). These results are compared with 2024 HelioCon performance targets, and our planned next steps for the ReTNA measurement system are presented.

CSP↗
DOE OSTI2026

In Situ Measurements of the Reflectances of the LSSTCam Optics and Assessing the Impact of Optical Ghosts

Optical ghosts are image artifacts caused by successive reflections of light between optical surfaces such as lenses, filters, and detectors. These artifacts are unavoidable due to the nonzero reflectances of optical elements and are a major source of contamination for low-surface-brightness science. We use optical ray tracing simulations tuned to observations from LSST Commissioning to quantify the impact of optical ghosts on the LSST data. In particular, we find that ~0.57% of the LSSTCam focal plane is impacted by optical ghosts when averaged across all bands. We also use data from the Collimated Beam Projector to measure the reflectances of various optical elements, generally confirming estimates of ~2% from the systems engineering throughput predictions.

Pai, Aashay↗
DOE OSTI2011

In situ imaging of orthoclase-aqueous solution interfaces with x-ray reflection interface microscopy

The use of x-ray reflection interface microscopy (XRIM) to image molecular-scale topography at the aqueous-solid interface, in situ, is described. Specifically, we image interfacial topography of the orthoclase-(001)-aqueous solution interface at room temperature and describe the challenges associated with in situ XRIM imaging. The measurements show that the reflectivity signal for in situ XRIM measurements is substantially smaller than that for ex situ measurements, because of both intrinsic and extrinsic factors. There is also a systematic temporal reduction in the image intensity with increasing x-ray dose, revealing that interaction of the focused x-ray beam with the orthoclase interfaces leads to interfacial perturbations, presumably in the form of surface roughening. This image fading is localized to the x-ray beam footprint, suggesting that the primary damage mechanism is initiated by photoelectrons produced by x-ray beam absorption near the substrate-electrolyte interface. Finally, the role of aqueous solution composition in controlling the sensitivity of the orthoclase surface to x-ray beam-induced effects is explored. A substantial increase in the orthoclase (001) surface stability was observed in solutions having elevated ionic strength, apparently as a result of the reduced lifetime of radiation chemistry products at these conditions.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Analysis of order contamination from toroidal grating monochromator of Indus-1 reflectivity beamline

The synchrotron radiation spectra of toroidal grating monochromators (TGM) often contaminated by significant amounts of higher orders. Quantitative estimation of order contamination is essential in order to perform quantitative spectroscopy measurements. At Indus-1 reflectivity beamline higher order contaminations from TGM monochromator are experimentally determined using a reflection grating analyzer. It is found that the order contamination in wavelength range of 50-200 A is less than 15%. Use of edge filters reduces the order contamination level below 5% in this wavelength range.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

Three dimensional reflectance properties of plasma dielectric photonic crystal

In this present communication, we study the three dimentionalomni-directional reflection bands in Plasma Photonic Crystals (PPC), having alternate regions of plasma-dielectric. We have calculated the reflectivity of the proposed structure at the various angles of incidence for both polarizations (TE - & TM) in three dimensions.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2012

Subluminal and superluminal parametric doppler effects in the case of light reflection from a moving smooth medium inhomogeneity

The reflection of test radiation from a smooth inhomogeneity of medium characteristics propagating with a subluminal or superluminal velocity is analyzed. The equations describing the propagation of the forward- and counter-propagating waves in such an inhomogeneous medium are derived. Quasi-phase conjugation is demonstrated in the case of superluminal inhomogeneities. The Bragg resonance conditions are formulated and the conditions for increasing the reflection coefficient of radiation from an inhomogeneity are discussed.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS2014

Is There Spectral Variation in the Polarized Reflectance of Leaves?

The light scattered by plant canopies depends in part on the light scattering/absorbing properties of the leaves and is key to understanding the remote sensing process in the optical domain. Here we specifically looked for evidence of fine spectral detail in the polarized portion of the light reflected from the individual leaves of five species of plants measured at Brewsters angle over the wavelength range 450 to 2300nm. Our results show no strong, unambiguous evidence of narrow band spectral variation of the polarized portion of the reflectance factor.

quasi specular reflection↗
DOE OSTI2018

Study of the Au-Cr bilayer system using X-ray reflectivity, GDOES, and ToF-SIMS

Here, we study a Au (25 nm)/Cr (10 nm) bilayer system as a model of mirror for the soft X–ray energy range. The Au and Cr thin films are a few nanometer thick and are deposited on a float glass substrate. The sample is characterized by using 3 complementary techniques: soft X–ray reflectivity, glow discharge optical emission spectrometry (GDOES), and time–of–flight secondary ion mass spectroscopy (ToF–SIMS). Soft X–ray reflectivity provides information about the thickness and roughness of the different layers, while GDOES is used to obtain the elemental depth profile of the stack and ToF–SIMS to obtain the elemental and chemical depth profiles. GDOES and ToF–SIMS have both a nanometer depth resolution. A coherent description of the bilayer stack is obtained through the combination of these techniques. It consists in 5 layers namely a surface contamination layer, a principal gold layer, a Au–Cr mixed layer, a Cr layer, and another contamination layer at the top of the substrate.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Determination of the Ability to Measure Traces of Water in Dehydrated Residues of Waste Water by IR Diffuse Reflectance Spectra

Rapid measurement of the moisture content of dehydrated residues is a critical problem, the solution of which will increase the efficiency of treatment facilities and optimize the process of applying flocculants. The ability to determine the moisture content of dehydrated residues using a meter operating on the IR reflectance principle was confirmed experimentally. The most suitable interference filters were selected based on an analysis of the obtained diffuse reflectance spectrum of the dehydrated residue in the range 1.0–2.7 μm. Calibration curves were constructed and compared for each filter set. A measuring filter with a transmittance maximum at 1.19 μm and a reference filter with a maximum at 1.3 μm gave the best agreement with the laboratory measurements.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Spectral reflectance reconstruction with the locally weighted linear model

Spectral reflectance reconstruction by the local linear model has many advantages such as simple model structure, fast calculation speed and less chance to be over-fitting. However, local linear model often suffers from the outliers and prone to be under-fitting. In this paper, we propose a locally weighted linear model for spectral reflectance reconstruction. It improves the contribution of the local neighbors with higher similarity to the test point, which can reduce the influence of noisy points and redundant points. Experimental results show that the locally weighted linear model can effectively reduce the reconstruction error.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2025

Electronic Melting of Silicon in Nanostructures using X-ray Forbidden Bragg Reflections

Abstract We carried out a short beamtime at the Pohang Accelerator Laboratory x-ray Free Electron Laser to perform a pump-probe (PP) laser excitation diffraction experiment on the silicon (222) forbidden Bragg peak. To limit the x-ray penetration, we used a “device layer” silicon film wafer bonded to a silicon substrate. The sample, specially fabricated by MEMC Electronic Materials, had a Si(100) substrate bonded to a 170 nm Si(100) film rotated at 45° for crystallographic isolation. A second sample was reactive-ion-etched down to 52 nm thickness. In the silicon lattice, the covalent bonds are seen exclusively at the 222 reflection. Upon laser excitation, these electrons are expected to be excited to the valence band on femtosecond electronic time scales. The Si(222) reflection is therefore expected to be extinguished on this fast time scale, while the electron–phonon coupled acoustic response is determined by the lattice dynamics. The latter is determined by the speed of sound over the device thickness, which is in the mid-picosecond range.

77 NANOSCIENCE AND NANOTECHNOLOGY↗