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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 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
NASA NTRS2003

Application of a Split-Fiber Probe to Velocity Measurement in the NASA Research Compressor

A split-fiber probe was used to acquire unsteady data in a research compressor. The probe has two thin films deposited on a quartz cylinder 200 microns in diameter. A split-fiber probe allows simultaneous measurement of velocity magnitude and direction in a plane that is perpendicular to the sensing cylinder, because it has its circumference divided into two independent parts. Local heat transfer considerations indicated that the probe direction characteristic is linear in the range of flow incidence angles of +/- 35. Calibration tests confirmed this assumption. Of course, the velocity characteristic is nonlinear as is typical in thermal anemometry. The probe was used extensively in the NASA Glenn Research Center (GRC) low-speed, multistage axial compressor, and worked reliably during a test program of several months duration. The velocity and direction characteristics of the probe showed only minute changes during the entire test program. An algorithm was developed to decompose the probe signals into velocity magnitude and velocity direction. The averaged unsteady data were compared with data acquired by pneumatic probes. An overall excellent agreement between the averaged data acquired by a split-fiber probe and a pneumatic probe boosts confidence in the reliability of the unsteady content of the split-fiber probe data. To investigate the features of unsteady data, two methods were used: ensemble averaging and frequency analysis. The velocity distribution in a rotor blade passage was retrieved using the ensemble averaging method. Frequencies of excitation forces that may contribute to high cycle fatigue problems were identified by applying a fast Fourier transform to the absolute velocity data.

Lepicovsky, Jan↗
DOE OSTI2025

Thermal and structural analysis of a new WEST reciprocating probe head with Titanium-Zirconium-Molybdenum armour material

The Tore Supra tokamak was transformed into an X-point divertor fusion device in the frame of the WEST (W-for tungsten-Environment in Steady-state Tokamak) project, launched in support of the ITER tungsten divertor strategy. WEST began operation in 2017. A new reciprocating probe head, equipped with a Titanium-Zirconium-Molybdenum (TZM) heat shield, was recently built and operated on WEST during the C9 Campaign in early 2024. TZM was chosen as armour material for its very good mechanical properties between 700 °C and 1400 °C. This material was already extensively used for probe heads and other plasma facing components on the Alcator C-Mod tokamak. Here, this paper presents the design of the new WEST probe head. It is equipped with tungsten filaments that can be heated to emit electrons and provide a direct measurement of the plasma potential in the scrape-off layer, and it is also equipped with a pair of Langmuir probes. The probe plunges vertically into the plasma, reaches its maximum dive depth, then returns to its protected resting position in about 0.25 s. Thermal loads are calculated using as input the thermal properties of TZM and radial profiles of the heat flux measured in the past by other reciprocating probes, and scaled upwards to the expected heat loads in the WEST scrape-off layer. An analytical estimation of Electromagnetic (EM) loads will also be presented, as well as a thermal and structural analysis of the probe for 15 cycles at maximum plunge depth. The probe is observed by an infrared camera. Comparisons between the heat flux deduced by the Langmuir probe and the infrared radiance of the probe housing during plasma exposure are finally presented.

Diagnostic↗
DOE OSTI2022

Atomic Force Microscope Active Optical Probe for Single-Molecule Imaging and Time-Resolved Optical Spectroscopy (DOE SBIR Phase II/IIA Final Report)

Actoprobe LLC reports on the results of its DOE SBIR Phase II/IIA project on the development of Atomic Force Microscope Active Optical Probe for Single-Molecule Imaging and Time-Resolved Optical Spectroscopy. While chemistry science and technology greatly benefit from Atomic Force Microscopy in surface characterization, time-resolved chemical imaging on the single-molecule level lags far behind. Current scanning probe microscopy only obtains information about mechanical but not optical/chemical properties. To address this problem, the Actoprobe LLC research team has proposed a novel class of Atomic Force Microscopy probes, Ultra-Fast Pulsed Active Atomic Force Microscopy Optical Probes (UFP AAOPs), that will allow ultrafast time-resolved optical and chemical imaging at the nanoscale. As envisioned, these unique optical probes will perform the functions of conventional Atomic Force Microscopy probes and, in addition, will simultaneously provide chemical information about molecular scale interactions. This innovation is accomplished by integrating an ultrafast pulsed Quantum Dot laser source into an Atomic Force Microscopy probe. This report describes our progress with the fabrication of an ultrafast micrometer-size semiconductor laser, based on “artificial atoms” - Quantum Dots, integrated with an Atomic Force Microscopy probe. In this Phase II/IIA project, we have demonstrated the feasibility of the UFP AAOP concept by fabricating a first prototype of the UFP AAOP. The excellent performance of the probe has been proven in terms of AFM and optical spatial resolution through rigorous tests. The UFP AAOP provides pulses with less than 4 ps duration and higher than 11 GHz repetition rate, and spatial resolution better than 300 nm at 1240 nm wavelength. Technically, it is possible to reduce the pulse width to less than 1 ps and to improve lateral resolution to ~ 0.5 nm, which implies the potential capability for the probe to characterize chemical compounds with single-molecule resolution. The UFP AAOP fabrication procedure has been developed for wafer-scale production of multiple devices, with the yield of the process estimated to be lower than 1% with the limited fabrication capabilities and equipment available for use in the research project. However, using high-volume production tools and special GaAs processing equipment, the yield can be significantly improved, theoretically to ~ 50%. Finally, economic feasibility and scale-up manufacturing potential were analyzed for UFP AAOP and found to be very promising. In summary, the Actoprobe team has successfully demonstrated the feasibility of the UFP AAOP concept.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Multiplexed Probing for Functional Capacity Measurements in Complex and Limited-Size Samples

A new strategy using glass as a solid support for functionalization with chemical probes has been recently developed with successful results. The next step in glass functionalization is to pair chemical probes with fluorescent glass microspheres. This approach gives us a way to directly quantify probe-bound protein using Fluorescence-Activated Cell Sorting (FACS). FACS has already shown to be amendable to glass microspheres, demonstrating changes in probe-bound protein concentration. Suitable probing conditions for gram-positive and negative microbes, complex microbial communities from myriad ecosystems, and eukaryotic cells/tissues have traditionally suffered from set-backs, such as limited protein per sample and conditions atypical for probing. To remedy this, we propose to: (1) Demonstrate probe functionalization specific to glass microspheres by paired fluorophore and use those activity probes successfully with proteomics. Probes that are currently available (CYP5, GSH/GST, Glycoside Hydrolase) can be easily prepared onto glass surfaces. Probe-bound microspheres can be tested in ratios, first with known amounts of purified protein and then complex microbiome lysates. (2) Our validated microspheres are then used to determine quantitative amounts of protein through FACS sorting. Complimenting these results by proteomics, prepared microspheres are then optimized and condensed into a user-friendly kit. Once successfully commercialized, this multiplexed assay can be used with little to no technical expertise, making this available to various industries users.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1986

The theory of Langmuir probes in strong electrostatic potential structures

The operation of collecting and emitting Langmuir probes and double probes within time-stationary strong electrostatic potential structures is analyzed. The cross sections of spherical and cylindrical probes to charged particles within the structures are presented and used to obtain the current-voltage characteristics of idealized probes. The acquisition of plasma parameters from these characteristics is outlined, and the operation of idealized floating double-probe systems is analyzed. Probe surface effects are added to the idealized theory, and some surface effects pertinent to spacecraft probes are quantified. Magnetic field effects on idealized probes are examined, and the time required for floating probes to change their potentials by collecting charge and by emitting photoelectrons is discussed. Calculations on the space-charge effects of probe-perturbed beams and on the space-charge limiting of electron emission are given in an appendix.

Borovsky, J. E.↗
NASA NTRS1995

Estimates of Heat Shielding Requirements for Saturn Probe Missions

Entry trajectories, decelerations, heating and heat shielding requirements of probes entering the atmosphere of Saturn at relative entry velocities ranging from 26.5 - 33.0 km/sec were studied. Much of the Galileo Jupiter probe technology was applicable to these outer planet probes; therefore, the same configuration was used. A wide range entry flight path angles were used in the trajectory analysis in order to satisfy the complete range of arrival conditions and trajectory requirements. Various entry probe sizes and a range of entry masses from 32 - 258 kg were considered. The carbon phenolic heat shield material used on the Galileo and the successful Pioneer-Venus probes was selected. Turbulent boundary layer convection dominated the heating of the Saturn probes; radiative heating was negligible by comparison at the entry velocities considered. The peak heating rates were found to be about 4 kW per square centimeter, or approximately 17% of the Galileo probe's expected maximum value. The forebody heat shield mass fractions for the Saturn probes were found to vary from about 0.18 to 0.28. By comparison, the Pioneer-Venus probes' heat shield mass fractions ranged from 0.10 to 0.13 and the Galileo probe's forebody value is 0.43.

Wercinski, P.↗
NASA NTRS2003

Science Rationale for Jupiter Entry Probe as Part of JIMO

A Jupiter atmospheric entry probe as part of JIMO is a cost effective way to address fundamental science questions identified in the National Research Council Solar System Exploration Decadal Survey (SSEDS): New Frontiers in the Solar System, An Integrated Ex- ploration Strategy. Compared to either the cost of an entirely separate Jupiter mission, or the cost of JIMO itself, inclusion of such a probe on JIMO would be cost advantageous. The probe itself could be relatively simple, and could build on the Galileo Probe heritage. The SSEDS specifically identified the distribution of water across the Solar System as a Key Scientific Question. Correspondingly, knowing the water abun dance on Jupiter is fundamental to understanding almost every aspect of the evolution of the early solar nebula. The Galileo Probe obtained the abundance of several key elements in Jupiter's atmosphere, which data have already caused major rethinking of theories of how Jupiter formed and how the early solar nebula evolved. However, because of a combination of circumstances, the global abundance of the key element oxygen, in the form of water, was not obtained. Without knowledge of the jovian water abundance, further progress in understanding Solar System evolution and planet formation will be greatly inhibited. Therefore, quantifying jovian water abundance should be a goal of the very next mission to the jovian system. Such a measurement would be impossible via remote sensing from the JIMO orbiter because of the large distances the JIMO orbiter maintains from Jupiter. A Jupiter atmospheric entry probe as part of JIMO could achieve the fundamental water measurement. In order that a probe avoid repeating the Galileo probe's experience of failing to obtain the jovian water abundance, the probe should go deep, to at least 100 bars pressure. Probes to 100 bars have been accomplished many times in descending to the surface of Venus, and at 100 bars the temperature of the jovian atmosphere is 60-70 K less than the surface temperature of Venus.

Young, R. E.↗
NASA NTRS2004

Probe Station Antenna Range

This summer I was given the task of programming a Probe Station to collect near field antenna patterns and convert them to far field patterns. The purpose of this project is to provide NASA with another means of antenna characterizing. Currently, NASA Glenn can measure near field and far field patterns of many different types of antennas. The antennas targeted for this lab are small patch antennas at high frequencies that require probe biasing. The Probe Station contains two probes for RF signals and another two for DC Biasing. The way this lab works is as follows: A patch antenna is placed on the probe station and biased properly for testing. This antenna is known as the Antenna Under Test (AUT). The AUT is supplied with an RF signal from a probe that is connected to a network analyzer. Above the AUT hangs a probe for measuring the electric field emitted by the AUT. The probe is controlled by four axis. The axis of movements for this probe are back and forth, left and right, up and down, and rotation. The network analyzer and axis controllers are tied into a computer for reading commands and recording data. The probe scans a rectangular pattern above the AUT to measure the electric field emitted by the AUT. This data is then recorded and analyzed back at the computer.

Zaman, Afroz↗
NASA NTRS2005

Synergy Between Entry Probes and Orbiters

We identify two catagories of probe-orbiter interactions which benefit the science return from a particular mission. The first category is termed "Mission Design Aspects". This category is meant to describe those aspects of the mission design involving the orbiter that affect the science return from the probe(s). The second category of probe-orbiter interaction is termed "Orbiter-Probe Science Interactions", and is meant to include interactions between oribter and probe(s) that directly involve science measurements made from each platform. Two mission related aspects of probe-orbiter interactions are delivery of a probe(s) to the entry site(s) by an orbiter, and communication between each probe and the orbiter. We consider four general probe-orbiter science interactions that greatly enhance, or in certain cases are essential for, the mission science return. The four topics are, global context of the probe entry site(s), ground truth for remote sensing observations of an orbiter, atmospheric composition measurements, and wind measurements.

Young, Richard E.↗
NASA NTRS2004

Hollow Cathode and Keeper-region Plasma Measurements Using Ultra-fast Miniature Scanning Probes

In order to support the development of comprehensive performance and life models for future deep space missions that will utilize ion thrusters, we have undertaken a study of the plasma structure in hollow cathodes using an new pneumatic scanning probe diagnostic. This device is designed to insert a miniature probe directly into the hollow cathode orifice from either the upstream insert region in the interior of the hollow cathode, or from the downstream keeper-plasma region at the exit of the hollow cathode, to provide complete axial profiles of the discharge plasma parameters. Previous attempts to diagnose this region with probes was Limited by the melting of small probes in the intense discharge near the orifice, or caused significant perturbation of the plasma by probes large enough to survive. Our new probe is extremely compact, and when configured as a single Langmuir probe, the ceramic tube insulator is only 0.5mm in diameter and the current collecting conductor has a total area of 0.002 cm2. A series of current-voltage characteristics are obtained by applying a rapid sawtooth voltage waveform to the probe as it is scanned by the pneumatic actuator into and out of the plasma region, The bellow-sealed pneumatic drive scans the probe 4 cm in the cathode insert region and 10 cm in the anode/keeper plasmas region at average speeds of about 1 mm/msec, and the residence time at the end of the insertion stroke in the densest part of the plasma near the orifice is measured to be only 10 msec. Since the voltage sweep time is fast compared to the motion of the probe, axial profiles of the plasma density, temperature and potential with reasonable spatial resolution are obtained. Measurements of the internal cathode pressures and the axial plasma-parameter profiles for a hollow cathode operating at discharge currents of up to 35 A in xenon will be presented.

plasma generation↗
NASA NTRS2008

Effects of a Rotating Aerodynamic Probe on the Flow Field of a Compressor Rotor

An investigation of distortions of the rotor exit flow field caused by an aerodynamic probe mounted in the rotor is described in this paper. A rotor total pressure Kiel probe, mounted on the rotor hub and extending up to the mid-span radius of a rotor blade channel, generates a wake that forms additional flow blockage. Three types of high-response aerodynamic probes were used to investigate the distorted flow field behind the rotor. These probes were: a split-fiber thermo-anemometric probe to measure velocity and flow direction, a total pressure probe, and a disk probe for in-flow static pressure measurement. The signals acquired from these high-response probes were reduced using an ensemble averaging method based on a once per rotor revolution signal. The rotor ensemble averages were combined to construct contour plots for each rotor channel of the rotor tested. In order to quantify the rotor probe effects, the contour plots for each individual rotor blade passage were averaged into a single value. The distribution of these average values along the rotor circumference is a measure of changes in the rotor exit flow field due to the presence of a probe in the rotor. These distributions were generated for axial flow velocity and for static pressure.

Lepicovsky, Jan↗
NASA NTRS2007

Waveguide Calibrator for Multi-Element Probe Calibration

A calibrator, referred to as the spider design, can be used to calibrate probes incorporating multiple acoustic sensing elements. The application is an acoustic energy density probe, although the calibrator can be used for other types of acoustic probes. The calibrator relies on the use of acoustic waveguide technology to produce the same acoustic field at each of the sensing elements. As a result, the sensing elements can be separated from each other, but still calibrated through use of the acoustic waveguides. Standard calibration techniques involve placement of an individual microphone into a small cavity with a known, uniform pressure to perform the calibration. If a cavity is manufactured with sufficient size to insert the energy density probe, it has been found that a uniform pressure field can only be created at very low frequencies, due to the size of the probe. The size of the energy density probe prevents one from having the same pressure at each microphone in a cavity, due to the wave effects. The "spider" design probe is effective in calibrating multiple microphones separated from each other. The spider design ensures that the same wave effects exist for each microphone, each with an indivdual sound path. The calibrator s speaker is mounted at one end of a 14-cm-long and 4.1-cm diameter small plane-wave tube. This length was chosen so that the first evanescent cross mode of the plane-wave tube would be attenuated by about 90 dB, thus leaving just the plane wave at the termination plane of the tube. The tube terminates with a small, acrylic plate with five holes placed symmetrically about the axis of the speaker. Four ports are included for the four microphones on the probe. The fifth port is included for the pre-calibrated reference microphone. The ports in the acrylic plate are in turn connected to the probe sensing elements via flexible PVC tubes. These five tubes are the same length, so the acoustic wave effects are the same in each tube. The flexible nature of the tubes allows them to be positioned so that each tube terminates at one of the microphones of the energy density probe, which is mounted in the acrylic structure, or the calibrated reference microphone. Tests performed verify that the pressure did not vary due to bends in the tubes. The results of these tests indicate that the average sound pressure level in the tubes varied by only 0.03 dB as the tubes were bent to various angles. The current calibrator design is effective up to a frequency of approximately 4.5 kHz. This upper design frequency is largely due to the diameter of the plane-wave tubes.

Sommerfeldt, Scott D.↗
DOE OSTI2016

Characterizing nanoscale scanning probes using electron microscopy: A novel fixture and a practical guide

The nanoscale geometry of probe tips used for atomic force microscopy (AFM) measurements determines the lateral resolution, contributes to the strength of the tip-surface interaction, and can be a significant source of uncertainty in the quantitative analysis of results. While inverse imaging of the probe tip has been used successfully to determine probe tip geometry, direct observation of the tip profile using electron microscopy (EM) confers several advantages: it provides direct (rather than indirect) imaging, requires fewer algorithmic parameters, and does not require bringing the tip into contact with a sample. In the past, EM-based observation of the probe tip has been achieved using ad hoc mounting methods that are constrained by low throughput, the risk of contamination, and repeatability issues. We report on a probe fixture designed for use in a commercial transmission electron microscope that enables repeatable mounting of multiple AFM probes as well as a reference grid for beam alignment. This communication describes the design, fabrication, and advantages of this probe fixture, including full technical drawings for machining. Further, best practices are discussed for repeatable, non-destructive probe imaging. Finally, examples of the fixture’s use are described, including characterization of common commercial AFM probes in their out-of-the-box condition.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Reproducibility of the cutoff probe for the measurement of electron density

Since a plasma processing control based on plasma diagnostics attracted considerable attention in industry, the reproducibility of the diagnostics using in this application has become a great interest. Because the cutoff probe is one of the potential candidates for this application, knowing the reproducibility of the cutoff probe measurement becomes quit important in the cutoff probe application research. To test the reproducibility of the cutoff probe measurement, in this paper, a comparative study among the different cutoff probe measurements was performed. The comparative study revealed remarkable result: the cutoff probe has a great reproducibility for the electron density measurement, i.e., there are little differences among measurements by different probes made by different experimenters. The discussion including the reason for the result was addressed via this paper by using a basic measurement principle of cutoff probe and a comparative experiment with Langmuir probe.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2017

Is the Collecting Surface of a Flat One-Sided Probe Constant when Measuring the Ion Distribution Function?

The correctness of the known plane single-ended probe method for measuring the anisotropic ion distribution functions in a gas-discharge plasma has been considered. Analysis has been performed for positive probe potentials relative to the plasma with magnitudes on the order of the mean ion energy, which as a rule is much lower than the mean electron energy. We have analyzed the dependence of the collection surface area of a plane probe on its potential in this range. The structure of the near-probe layer has been determined for an isotropic electron distribution function of the Maxwellian or Druvestein type and an anisotropic ion distribution function. These results are used to derive analytic relations for the correction to the second derivative of the probe current with respect to the plane probe potential. It has been shown that, when the ion distribution function is measured in a wide range of conditions in the gas-discharge plasma, when the approximation of a collisionless probe layer is applicable, and the probe does not perturb the plasma, the dependence of the collection surface area of the probe on the potential can be disregarded in this range.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRSDate not supplied

Uranus Probe Entry and Descent Mission Concept

Introduction: Uranus was identified as the third highest priority flagship mission in the 2012-2022 Planetary Science Decadal Survey. This latest concept study was requested by the Decadal Survey panel to determine NASA’s planetary science priorities from 2022-2032. This study focused on the probe’s entry and descent aspects and associated trades for viable trajectory options. Uranus Mission and Descent Probe: The proposed Uranus Orbiter and Probe (UOP) Flagship mission will investigate Uranus and its surrounding moons using an orbiting spacecraft with a Uranus descent probe. Unlike previous studies the probe release will occur after orbit insertion allowing sufficient separation of critical events during the orbit insertion burn. The probe will be released at an altitude that allows one hour of in situ atmospheric readings that will be relayed to the orbiter. Afterwards the orbiter will transition to the moon tour phase of the mission. The configuration chosen for the entry aeroshell was a 45° sphere-cone. This shape has been used in the past in the Pioneer Venus Galileo missions. However, the nose radius considered in the present study differed from the values used in either of the previous configurations, primarily to reduce the heat flux at the stagnation point. A two-step approach was used in the development of flight trajectories for the chosen configuration. In the first step, the trajectory code POST2 was used to screen the thousands of entry states provided by interplanetary trajectory simulations, which were terminated at an altitude of 2000 km from the reference surface (1 bar) of Uranus. The screening criteria were: (i) optimization of the communication geometry between the entry probe and orbiter to ensure at least 1 hour of science measurements, (ii) peak stagnation point pressures to be less than six bar, (iii) peak heat fluxes to be less than 5 kW/cm2; the latter two constraints being the limits of ground-test capabilities of the arc jets at NASA Ames Research Center. The entry team investigated two trajectories that met the criteria above, a shallow entry (high heat load ~44 kJ/cm2) and a steeper entry (high heat rate ~1950 W/cm2). In the second step, the two bounding candidate entry states from the POST2 screening process were used in developing flight trajectories using TRAJ coupled with FIAT (a materials thermal response and sizing code) and a margins policy to determine a margined uniform thickness (hence mass) of the forward heatshield material based on the aerothermal environments at the stagnation point. Since the combination of TRAJ and FIAT size the TPS based on stagnation point environments only, flow field computations using DPLR were necessary to determine turbulent aerothermal environments on the conical flank, and the augmentation of these environments due to surface roughness. The environments at select locations on the forward heatshield were then used to size the thermal protection material, with the largest thickness value then used to estimate the mass. The newly developed woven thermal protection material –HEEET (Heatshield for Extreme Entry Environments Technology) –was considered for the forward heatshield and PICA (Phenolic-Impregnated Carbon Ablator) was considered for the backshell. These NASA-developed materials are at TRL 6 and TRL 9, respectively. Furthermore, two options were considered for the HEEET material: (i) a dual-layer option with a denser recession layer on top and an insulative layer underneath it, and (ii) a single layer option consisting of the insulative layer alone. Results: It is clear that probe entry states are feasible and the selected TPS options are able to perform in the predicted aerothermal environments thus enabling the mission to meet of the descent probe portion of this flagship mission

Entry Descent and Landing↗
DOE OSTI2019

ATLAS probe: Breakthrough science of galaxy evolution, cosmology, Milky Way, and the Solar System

Astrophysics Telescope for Large Area Spectroscopy Probe is a concept for a National Aeronautics and Space Administration probe-class space mission that will achieve ground-breaking science in the fields of galaxy evolution, cosmology, Milky Way, and the Solar System. It is the follow-up space mission to Wide Field Infrared Survey Telescope (WFIRST), boosting its scientific return by obtaining deep 1–4 μm slit spectroscopy for ~70% of all galaxies imaged by the ~2 000 deg 2 WFIRST High Latitude Survey at z > 0.5. Astrophysics Telescope for Large Area Spectroscopy will measure accurate and precise redshifts for ~200 M galaxies out to z < 7, and deliver spectra that enable a wide range of diagnostic studies of the physical properties of galaxies over most of cosmic history. Astrophysics Telescope for Large Area Spectroscopy Probe and WFIRST together will produce a 3D map of the Universe over 2 000 deg 2 , the definitive data sets for studying galaxy evolution, probing dark matter, dark energy and modifications of General Relativity, and quantifying the 3D structure and stellar content of the Milky Way. Astrophysics Telescope for Large Area Spectroscopy Probe science spans four broad categories: (1) Revolutionising galaxy evolution studies by tracing the relation between galaxies and dark matter from galaxy groups to cosmic voids and filaments, from the epoch of reionisation through the peak era of galaxy assembly; (2) Opening a new window into the dark Universe by weighing the dark matter filaments using 3D weak lensing with spectroscopic redshifts, and obtaining definitive measurements of dark energy and modification of General Relativity using galaxy clustering; (3) Probing the Milky Way’s dust-enshrouded regions, reaching the far side of our Galaxy; and (4) Exploring the formation history of the outer Solar System by characterising Kuiper Belt Objects. Astrophysics Telescope for Large Area Spectroscopy Probe is a 1.5 m telescope with a field of view of 0.4 deg 2 , and uses digital micro-mirror devices as slit selectors. It has a spectroscopic resolution of R = 1 000, and a wavelength range of 1–4 μm. The lack of slit spectroscopy from space over a wide field of view is the obvious gap in current and planned future space missions; Astrophysics Telescope for Large Area Spectroscopy fills this big gap with an unprecedented spectroscopic capability based on digital micro-mirror devices (with an estimated spectroscopic multiplex factor greater than 5 000). Astrophysics Telescope for Large Area Spectroscopy is designed to fit within the National Aeronautics and Space Administration probe-class space mission cost envelope; it has a single instrument, a telescope aperture that allows for a lighter launch vehicle, and mature technology (we have identified a path for digital micro-mirror devices to reach Technology Readiness Level 6 within 2 yr). In conclusion, Astrophysics Telescope for Large Area Spectroscopy Probe will lead to transformative science over the entire range of astrophysics: from galaxy evolution to the dark Universe, from Solar System objects to the dusty regions of the Milky Way

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

A robust high sensitivity scanning thermal probe for simultaneous microscale thermal and thermoelectric property mapping

Scanning Thermal Microscopy (SThM) provides efficient thermal property measurement with micro- or nanoscale spatial resolution. However, the sensitivity and accuracy of state-of-the-art thermal probes have been limited by excessive thermal contact resistance between the probe and sample. Introduced herein is a robust thermal microprobe that can increase the probe-sample contact force by more than two orders of magnitude, thereby reducing the probe-sample thermal contact resistance by as much as 96% and increasing measurement sensitivity by more than 240% compared to a commercial thermal probe with the same dimensions and measurement principle. The relationship between the probe-sample thermal contact resistance, thermal exchange radius, and sample thermal conductivity is determined experimentally. Simultaneous measurement of thermal conductivity and Seebeck coefficient with unprecedented sensitivity is demonstrated using the enhanced scanning thermal microprobe on samples of an extended range of thermal conductivity up to 18 W/m K, increasing the range of samples applicable to SThM when compared to the conventional commercial probe with diminished measurement sensitivity above ~10 W/m K. The probe is further demonstrated by simultaneously mapping thermal conductivity and Seebeck coefficient as a function of depth from the irradiated surface of an ion-irradiated bulk nanostructured thermoelectric material. In addition to enabling microscale thermal conductivity and Seebeck coefficient measurement of materials previously not applicable to SThM, the probe can also facilitate high-throughput characterization of combinatorial materials to aid the rapid discovery of compositions and processing conditions that yield highly desired thermal and thermoelectric properties.

36 MATERIALS SCIENCE↗