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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Note: A stand on the basis of atomic force microscope to study substrates for imaging optics

A description of a stand based on atomic force microscopy (AFM) for roughness measurements of large optical components with arbitrary surfaces is given. The sample under study is mounted on a uniaxial goniometer which allows the sample to be tilted in the range of ±30°. The inclination enables the local normal along the axis of the probe to be established at any point of the surface under study. A comparison of the results of the measurement of noise and roughness of a flat quartz sample, in the range of spatial frequencies 0.025–70 μm{sup −1}, obtained from “standard” AFM and developed versions is given. Within the experimental error, the measurement results were equivalent. Examples of applications of the stand for the study of substrates for X-ray optics are presented.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

Accessing the Intrinsic Spin Transport in a Topological Insulator by Controlling the Crossover of Bulk-to-Surface Conductance

Here we report a method to control contributions of bulk and surface states in the topological insulator Bi 2 Te 2 Se that allows accessing the spin-polarized transport endowed by topological surface states. An intrinsic surface dominant transport is established when cooling the sample to low temperature or reducing the conduction channel length, both achieved in situ in the transport measurements with a four-probe scanning tunneling microscope without the need of further tailoring the sample. The topological surface states show characteristic transport behaviors with mobility about an order of magnitude higher than reported before, and a spin polarization approaching the theoretically predicted value. Our result demonstrates accessibility to the intrinsic high mobility spin transport of topological surface states, which paves a way to realizing topological spintronic devices.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Measurement of Young's modulus variation with layer pair and interplanar spacing in gold–nickel nanolaminates using nanoindentation and the tapping mode

The features of grain size and interface separation strengthen the mechanical behavior of metallic nanolaminates. In addition, the presence of interlayer lattice strains can lead to a superlattice structure within the nanolaminate. The superlattice affects intrinsic properties of technological interest including electronic, magnetic, and elastic. The complex elastic and plastic behaviors of gold–nickel nanolaminate superlattice coatings as studied using nanoindentation are revisited with the tapping mode of a force microscope. Young's modulus is determined with nanoindentation during the initial elastic unloading after plastic deformation at depths up to one-fifth the coating thickness. The tapping mode provides a measurement during the initial elastic deformation at depths of only a few nanometers. The tapping mode utilizes the shift in the resonant frequency of the probe-cantilever system as contact is made with the sample surface. Both of these nanoprobe test methods produce results for measurements conducted with loading normal to the surface plane. A softening in the Young's modulus of gold–nickel nanolaminate coatings occurs for samples with layer pair spacing between 1 and 9 nm. The magnitude of softening corresponds with a progressive increase in the tensile state as measured with the change of interplanar spacing along the growth direction.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS1984

Data documentation for the bare soil experiment at the University of Arkansas, June - August 1980

The primary objective of this study is to evaluate the relationships between soil moisture and reflectivity of a bare soil, using microwave techniques. A drainage experiment was conducted on a Captina silt loam in cooperation with personnel in the Electrical Engineering Department. Measurements included soil moisture pressures at various depths, neutron probe measurements, gravimetric moisture samples, and reflectivity of the soil surface at selected frequencies including 1.5 and 6.0 GHz and at the incident angle of 45 deg. All measurements were made in conjuction with that of reflectivity data.

Sadeghi, A. M.↗
NASA NTRS1990

Design of a scientific probe for obtaining Mars surface material

The objective is to return a 1 Kg Martian soil sample from the surface of Mars to a mothership in a 60 km Mars orbit. Given here is information on the mission profile, the structural design and component placement, thermal control and guidance, propulsion systems, orbital mechanics, and specialized structures.

Baker, Miles↗
NASA NTRS2012

Next-Generation Tumbleweed Rover

A document describes a next-generation tumbleweed rover that involves a split balloon system that is made up of two half-spherical air bladders with a disc between them. This disc contains all the electronics and instruments. By deflating only the bottom balloon, the rover can sit, bringing the surface probe into contact with the ground. The bottom balloon has a channel passing through it, allowing the surface probe to reach the surface through the balloon. Once the sample has been gathered and analyzed, the rover can re-inflate the lower air bladder and continue rolling. The rover will use a small set of instruments and electronics situated at the center of its inflatable spherical hull. The current version is a large beach-ball-like construction, about 1.8 m in diameter and weighing roughly 15 kg. The rover comprises two major parts, an outer spherical hull (split in half at the central disc) and an inner, disc-shaped cylindrical section. The balloons are attached to the bottom and top of the disc. Inside the disc, there are temperature and pressure sensors to keep track of the inner and outer conditions of the rover. A system of pumps and valves is responsible for independently inflating and deflating the balloons as necessary. There are also accelerometers to record the movement, together with a GPS receiver. The data are then sent through a modem to a control station. This work builds upon the project Tumbleweed rover for planetary exploration, described in the Technical Support Package.

Nosanov, Jeffrey P.↗
DOE OSTI2015

dropletProbe Premium v1.201

Selects locations of interest for liquid microjunction surface sampling coupled to a subsequent analysis is done in a user friendly way. That information is then transferred to instrument control softwares. In addition, readout of a laser sensor allows for robust probe-to-surface distance measurement. Furthermore, pictures taken by the software from a camera provides feedback to judge on successful microjunction sampling.

Kertesz, Vilmos↗
DOE OSTI2023

Cinematic reflectometry using QIKR, the quite intense kinetics reflectometer

The Quite Intense Kinetics Reflectometer (QIKR) will be a general-purpose, horizontal-sample-surface neutron reflectometer. Reflectometers measure the proportion of an incident probe beam reflected from a surface as a function of wavevector (momentum) transfer to infer the distribution and composition of matter near an interface. The unique scattering properties of neutrons make this technique especially useful in the study of soft matter, biomaterials, and materials used in energy storage. Exploiting the increased brilliance of the Spallation Neutron Source Second Target Station, QIKR will collect specular and off-specular reflectivity data faster than the best existing such machines. It will often be possible to collect complete specular reflectivity curves using a single instrument setting, enabling “cinematic” operation, wherein the user turns on the instrument and “films” the sample. Samples in time-dependent environments (e.g., temperature, electrochemical, or undergoing chemical alteration) will be observed in real time, in favorable cases with frame rates as fast as 1 Hz. Cinematic data acquisition promises to make time-dependent measurements routine, with time resolution specified during post-experiment data analysis. This capability will be deployed to observe such processes as in situ polymer diffusion, battery electrode charge–discharge cycles, hysteresis loops, and membrane protein insertion into lipid layers.

47 OTHER INSTRUMENTATION↗
DOE OSTI2011

Combining Transmission Geometry Laser Ablation and a Non Contact Continuous Flow Surface Sampling Probe/Electrospray Emitter for Mass Spectrometry-Based Chemical Imaging

This paper describes the coupling of ambient pressure transmission geometry laser ablation with a liquid phase sample collection into a continuous flow surface sampling probe/electrospray emitter for mass spectrometry based chemical imaging. The flow probe/emitter device was placed in close proximity to the surface to collect the sample plume produced by laser ablation. The sample collected was immediately aspirated into the probe and on to the electrospray emitter, ionized and detected with the mass spectrometer. Freehand drawn ink lines and letters and an inked fingerprint on microscope slides were analyzed. The circular laser ablation area was about 210 m in diameter and under the conditions used in these experiments the spatial resolution, as determined by the size of the surface features distinguished in the chemical images, was about 100 m.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1972

Development, fabrication and testing of a magnetically connected plastic vacuum probe surface sampler

The sampler utilizes permanent magnets and soft metal pole pieces to connect the cone/filter assembly to the sampling head and vacuum supply. The cone/filter assembly is packaged in a plastic container and presterilized so that the need for any human contact during the sampling procedure is completely eliminated. Microbiological tests have demonstrated that the sampling efficiency is not affected by the magnetic coupling apparatus and that the probe appears to function as efficiently as the conventional plastic and Sandia vacuum probes.

Phillips, G. B.↗
DOE OSTI2024

Design and analysis of actively-cooled, edge-transport diagnostic for long-pulsed operation in WEST

Next step fusion devices that will operate in steady-state will require complex plasma-facing components (PFCs) that can survive the harsh environment over long timescales not common in current devices. This will require robust plasma facing surfaces that are integrated with active cooling systems. In a collaboration between CEA and ORNL, a plasma-interacting diagnostic is being designed for the W Environment in Steady-state Tokamak (WEST) in Cadarache, France which requires plasma-facing protection like those needed for steady-state PFCs. This integrated diagnostic studies edge transport and impurity migration within WEST, and is planned to include imbedded temperature Langmuir probe sensors, as well as removeable sample slots for ex-situ surface analysis of plasma-material interactions. The entire assembly is expected to move into the plasma edge for periods up to 1000 s having an energy removeable capability of ∼6 kW and seeing a peak heat flux of more than 7 MW/m2. The assembly compliments WEST high fluence campaigns that plan for multiple 1000 s pulses. Within these specifications, the assembly will require a refractory metal plasma facing surface and integral cooling in order to function within the limited space allotted for such diagnostics. Because of the limited space and linear actuator needs, additive manufacturing of the high heat flux working end of the assembly is being considered which could allow for precision cooling-channels and lighter weight designs. Conceptual design along with simulation and analysis results will be presented for this complex diagnostic with novel PFCs.

Lumsdaine, Arnold↗
DOE OSTI2015

SU-C-303-05: Photosensitizer Determination for PDT Using Interstitial and Surface Measurements of Fluorescence

Purpose: Photosensitizer concentration during photodynamic therapy (PDT) is an important parameter for accurate dosimetry. Fluorescence signal can be used as a measure of photosensitizer concentration. Two methods of data acquisition were compared to an ex vivo study both for in vivo and phantom models. Methods: Fluorescence signal of commonly used photosensitizer benzoporphyrin derivative monoacid ring A (BPD) was obtained in phantoms and mouse tumors using an excitation light of 405 nm. Interstitial fluorescence signal was obtained using a side-cut fiber inserted into the tumor tissue of interest. Using a previously developed multi-fiber probe, tumor surface fluorescence measurements were also collected. Signals were calibrated according to optical phantoms with known sensitizer fluorescence. Optical properties for each sample were determined and the influence of different absorption and scattering properties on the fluorescence signals was investigated. Using single value decomposition of the spectra, the sensitizer concentration was determined using the two different measurement geometries. An ex vivo analysis was also performed for tumor samples to determine the sensitizer concentration. Results: The two fluorescence signals obtained from the surface multi-fiber probe and the interstitial measurements were compared and were corresponding for both phantoms and mouse models. The values obtained were comparable to the ex vivo measurements as well. Despite the difference in geometry, the surface probe measurements can still be used as a metric for determining the presence of sensitizer in small volume tumors. Conclusion: The multi-fiber contact probe can be used as a tool to measure fluorescence at the surface of the treatment area for PDT and predict sensitizer concentration throughout the tumor. This is advantageous in that the measurement does not damage any tissue. Future work will include investigating the dependence of these results on intratumor sensitizer distribution.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2022

Optical recognition of constructs using hyperspectral imaging and detection (ORCHID)

Abstract Challenges to deep sample imaging have necessitated the development of special techniques such as spatially offset optical spectroscopy to collect signals that have travelled through several layers of tissue. However, these techniques provide only spectral information in one dimension (i.e., depth). Here, we describe a general and practical method, referred to as Optical Recognition of Constructs Using Hyperspectral Imaging and Detection (ORCHID). The sensing strategy integrates (1) the spatial offset detection concept by computationally binning 2D optical data associated with digital offsets based on selected radial pixel distances from the excitation source; (2) hyperspectral imaging using tunable filter; and (3) digital image binding and collation. ORCHID is a versatile modality that is designed to collect optical signals deep inside samples across three spatial (X, Y, Z) as well as spectral dimensions. The ORCHID method is applicable to various optical techniques that exhibit narrow-band structures, from Raman scattering to quantum dot luminescence. Samples containing surface-enhanced Raman scattering (SERS)-active gold nanostar probes and quantum dots embedded in gel were used to show a proof of principle for the ORCHID concept. The resulting hyperspectral data cube is shown to spatially locate target emitting nanoparticle volumes and provide spectral information for in-depth 3D imaging.

47 OTHER INSTRUMENTATION↗
DOE OSTI2013

Electric force microscopy of semiconductors: Theory of cantilever frequency fluctuations and noncontact friction

An electric force microscope employs a charged atomic force microscope probe in vacuum to measure fluctuating electric forces above the sample surface generated by dynamics of molecules and charge carriers. We present a theoretical description of two observables in electric force microscopy of a semiconductor: the spectral density of cantilever frequency fluctuations (jitter), which are associated with low-frequency dynamics in the sample, and the coefficient of noncontact friction, induced by higher-frequency motions. The treatment is classical-mechanical, based on linear response theory and classical electrodynamics of diffusing charges in a dielectric continuum. Calculations of frequency jitter explain the absence of contributions from carrier dynamics to previous measurements of an organic field effect transistor. Calculations of noncontact friction predict decreasing friction with increasing carrier density through the suppression of carrier density fluctuations by intercarrier Coulomb interactions. The predicted carrier density dependence of the friction coefficient is consistent with measurements of the dopant density dependence of noncontact friction over Si. Our calculations predict that in contrast to the measurement of cantilever frequency jitter, a noncontact friction measurement over an organic semiconductor could show appreciable contributions from charge carriers.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS1974

Planetary mission summaries. Volume 1: Introduction and overview

Tabular synopses of twelve missions are presented along with the Mariner Jupiter/Saturn 1977 mission for comparison. Mission definitions considered include: Mars Polar Orbiter; Mars Surface Sample Return; Mars Rover; Marine Jupiter/Uranus 1979 with Uranus Entry Probe; Mariner Jupiter Orbiter; Mariner Mercury Orbiter 1978; Early Mariner Comet Flyby Solar Electric Encke Slow Flyby; Mariner Encke Ballistic Flyby; Solar Electric Encke Rendezvous 1981; Venus Orbital Imaging Radar; Solar Electric Out-of-the-Eliptic Probe 1979. Technical conclusions of mission studies are given in order that these results may interact with the broader questions of scope, pace, and priorities in the planetary exploration program.

Source record↗
NASA NTRS1997

Characterizing Surfaces of the Wide Bandgap Semiconductor Ilmenite with Scanning Probe Microcopies

Ilmenite (FeTiO3) is a wide bandgap semiconductor with an energy gap of about 2.5eV. Initial radiation studies indicate that ilmenite has properties suited for radiation tolerant applications, as well as a variety of other electronic applications. Two scanning probe microscopy methods have been used to characterize the surface of samples taken from Czochralski grown single crystals. The two methods, atomic force microscopy (AFM) and scanning tunneling microscopy (STM), are based on different physical principles and therefore provide different information about the samples. AFM provides a direct, three-dimensional image of the surface of the samples, while STM give a convolution of topographic and electronic properties of the surface. We will discuss the differences between the methods and present preliminary data of each method for ilmenite samples.

Wilkins, R.↗
NASA NTRS1987

Simulation of radar reflectivity and surface measurements of rainfall

Raindrop size distributions (RSDs) are often estimated using surface raindrop sampling devices (e.g., disdrometers) or optical array (2D-PMS) probes. A number of authors have used these measured distributions to compute certain higher-order RSD moments that correspond to radar reflectivity, attenuation, optical extinction, etc. Scatter plots of these RSD moments versus disdrometer-measured rainrates are then used to deduce physical relationships between radar reflectivity, attenuation, etc., which are measured by independent instruments (e.g., radar), and rainrate. In this paper RSDs of the gamma form as well as radar reflectivity (via time series simulation) are simulated to study the correlation structure of radar estimates versus rainrate as opposed to RSD moment estimates versus rainrate. The parameters N0, D0 and m of a gamma distribution are varied over the range normally found in rainfall, as well as varying the device sampling volume. The simulations are used to explain some possible features related to discrepancies which can arise when radar rainfall measurements are compared with surface or aircraft-based sampling devices.

Chandrasekar, V.↗
NASA NTRS2003

Instrument for Measuring Cryo CTE

Coefficient of thermal expansion is an integral part of the performance of optical systems, especially for those, which operate at cryogenic temperatures. The measurement of the coefficient of relevant materials has been of continuous interest. Besides commercial measurement sources, development of one-of-a-kind tools have always been of interest due to local needs. This paper describes one such development at the University of Alabama in Huntsville (UAH). The approach involves two vertical rods (one sample and one reference) on a flat platform. A probe bar is held horizontally atop the two samples. A temperature change will generally cause rotation of the probe bar. A mirrored surface on one end of the probe bar is used to measure the rotation using the reflection of an incident laser beam upon it. A position-sensing detector measures the change of the reflected beam spot position. Using other known quantities, the change determines the coefficient of thermal expansion of the sample material as a function of temperature. A parallel measurement of the rotation of the sample support platform is also performed to account for any unwanted background effects. This system has been demonstrated in a cryogenic chamber at the NASA Marshall Space Flight Center X-ray Calibration Facility (XRCF). We present the system details, achievable sensitivity, and up-to-date experimental performance.

Vikram, Chandra S.↗