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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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All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

A prototype scintillator real‐time beam monitor for ultra‐high dose rate radiotherapy

Background: FLASH Radiotherapy (RT) is an emergent cancer RT modality where an entire therapeutic dose is delivered at more than 1000 times higher dose rate than conventional RT. For clinical trials to be conducted safely, a precise and fast beam monitor that can generate out-of-tolerance beam interrupts is required. This paper describes the overall concept and provides results from a prototype ultra-fast, scintillator-based beam monitor for both proton and electron beam FLASH applications. Purpose: A FLASH Beam Scintillator Monitor (FBSM) is being developed that employs a novel proprietary scintillator material. The FBSM has capabilities that conventional RT detector technologies are unable to simultaneously provide: (1) large area coverage; (2) a low mass profile; (3) a linear response over a broad dynamic range; (4) radiation hardness; (5) real-time analysis to provide an IEC-compliant fast beam-interrupt signal based on true two-dimensional beam imaging, radiation dosimetry and excellent spatial resolution. Methods: The FBSM uses a proprietary low mass, less than 0.5 mm water equivalent, non-hygroscopic, radiation tolerant scintillator material (designated HM: hybrid material) that is viewed by high frame rate CMOS cameras. Folded optics using mirrors enable a thin monitor profile of ∼10 cm. A field programmable gate array (FPGA) data acquisition system generates real-time analysis on a time scale appropriate to the FLASH RT beam modality: 100–1000 Hz for pulsed electrons and 10–20 kHz for quasi-continuous scanning proton pencil beams. An ion beam monitor served as the initial development platform for this work and was tested in low energy heavy-ion beams ( 86 Kr +26 and protons). A prototype FBSM was fabricated and then tested in various radiation beams that included FLASH level dose per pulse electron beams, and a hospital RT clinic with electron beams. Results: Results presented in this report include image quality, response linearity, radiation hardness, spatial resolution, and real-time data processing. Furthermore, the HM scintillator was found to be highly radiation damage resistant. It exhibited a small 0.025%/kGy signal decrease from a 216 kGy cumulative dose resulting from continuous exposure for 15 min at a FLASH compatible dose rate of 237 Gy/s. Measurements of the signal amplitude versus beam fluence demonstrate linear response of the FBSM at FLASH compatible dose rates of >40 Gy/s. Comparison with commercial Gafchromic film indicates that the FBSM produces a high resolution 2D beam image and can reproduce a nearly identical beam profile, including primary beam tails. The spatial resolution was measured at 35–40 µm. Tests of the firmware beta version show successful operation at 20 000 Hz frame rate or 50 µs/frame, where the real-time analysis of the beam parameters is achieved in less than 1 µs. Conclusions: The FBSM is designed to provide real-time beam profile monitoring over a large active area without significantly degrading the beam quality. A prototype device has been staged in particle beams at currents of single particles up to FLASH level dose rates, using both continuous ion beams and pulsed electron beams. Using a novel scintillator, beam profiling has been demonstrated for currents extending from single particles to 10 nA currents. Radiation damage is minimal and even under FLASH conditions would require ≥50 kGy of accumulated exposure in a single spot to result in a 1% decrease in signal output. Beam imaging is comparable to radiochromic films, and provides immediate images without hours of processing. Real-time data processing, taking less than 50 µs (combined data transfer and analysis times), has been implemented in firmware for 20 kHz frame rates for continuous proton beams.

2D beam imaging↗
NASA NTRS2020

Measurements of Few-Mode Fiber Photonic Lanterns in Emulated Atmospheric Conditions for a Low Earth Orbit Space to Ground Optical Communication Receiver Application

Photonic lanterns are being evaluated as a component of a scalable photon counting real-time optical ground receiver for space-to-ground photon-starved communication applications. The function of the lantern as a component of a receiver is to efficiently couple and deliver light from the atmospherically distorted focal spot formed behind a telescope to multiple small-core fiber-coupled single-element super-conducting nanowire detectors. This architecture solution is being compared to a multimode fiber coupled to a multi-element detector array. This paper presents a set of measurements that begins this comparison. This first set of measurements are a comparison of the throughput coupling loss at emulated atmospheric conditions for the case of a 60 cm diameter telescope receiving light from a low earth orbit satellite. The atmospheric conditions are numerically simulated at a range of turbulence levels using a beam propagation method and are physically emulated with a spatial light modulator. The results show that for the same number of output legs as the single-mode fiber lantern, the few mode fiber lantern increases the power throughput up to 3.92 dB at the worst emulated atmospheric conditions tested of D/r0=8.6. Furthermore, the coupling loss of the few mode fiber lantern approaches the capability of a 30 micron graded index multimode fiber chosen for coupling to a 16 element detector array.

Tedder, Sarah A.↗
NASA NTRS1986

The development and test of multi-anode microchannel array detector systems. Part 2: Soft X-ray detectors

Detector systems based on the high gain microchannel plate (MCP) electron multiplier were used extensively for imaging at soft X-ray wavelengths both on the ground and in space. The latest pulse counting electronic readout systems provide zero readout noise, spatial resolutions (FWHM) of 25 microns or better and can determine the arrival times of detected photons to an accuracy of the order of 100 ns. These systems can be developed to produce detectors with active areas of 100 nm in diameter or greater. The use of CsI photocathodes produces very high detective quantum efficiencies at wavelengths between about 100 and 1A (approximately 0.1 to 10 keV) with moderate energy resolution. The operating characteristics of the different types of soft X-ray MCP detector systems are described and the prospects for future developments are discussed.

Timothy, J. G.↗
NASA NTRS1990

Amplitude and intensity spatial interferometry; Proceedings of the Meeting, Tucson, AZ, Feb. 14-16, 1990

Attention is given to such topics as ground interferometers, space interferometers, speckle-based and interferometry-based astronomical observations, adaptive and atmospheric optics, speckle techniques, and instrumentation. Particular papers are presented concerning recent progress on the IR Michelson array; the IOTA interferometer project; a space interferometer concept for the detection of extrasolar earth-like planets; IR speckle imaging at Palomar; optical diameters of stars measured with the Mt. Wilson Mark III interferometer; the IR array camera for interferometry with the cophased Multiple Mirror Telescope; optimization techniques appliesd to the bispectrum of one-dimensional IR astronomical speckle data; and adaptive optical iamging for extended objects.

Breckinridge, Jim B.↗
NASA NTRS2000

Discovery of Spatial and Spectral Structure in the X-Ray Emission from the Crab Nebula

The Chandra X-ray Observatory observed the Crab Nebula and Pulsar During orbital calibration. Zeroth-order images with the High-Energy Transmission Grating (HETG) read-out by the Advanced CCD Imaging Spectrometer spectroscopy array (ACIS-S) show a striking richness of X-ray structure, at a resolution comparable to that of the best ground-based visible-light observations. The HETG-ACIS-S images reveal, for the first time, an X-ray knots along the inner ring and (perhaps) along the inward extension of the X-ray jet. Although complicated by instrumental effects and the brightness of the Crab Nebula, the spectrometric analysis shows systematic variations of the X-ray spectrum throughout the Nebula.

Weisskopf, M.↗
DOE OSTI2022

Particulate Fuel Modeling of MC 2 -3 using Iterative Local Spatial Self-shielding Method

We report a new spatial self-shielding method for particulate fuels has been developed based on disadvantage factors and implemented in the MC 2 -3 code. This method named the iterative local spatial self-shielding (ILSS) method considers the shadowing effect of randomly distributed particles on spatial self-shielding in particles through a homogenized composition region added outside the particle of interest at the center. The self-shielded cross sections of the central particle are determined iteratively since they are used in determining the cross sections of the homogenized composition region. The ILSS method was verified for infinite stochastic medium problems of single and multiple types of particles, VHTR unit cell problems, and HTTR assembly problems. The verification test results show that the ILSS method accurately predicts the stochastic particle shadowing effect and reaction rates in particles, whereas the regular array model and the stochastic collision probability method underpredict the particle shadowing effect and overestimate reaction rates in particles.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2026

Anomalous Spin‐Optical Helical Effect in Ti‐Based Kagome Metal

The kagome lattice stands as a rich platform for hosting a wide array of correlated quantum phenomena, ranging from charge density waves and superconductivity to electron nematicity and loop current states. Direct detection of loop currents in kagome systems has remained a formidable challenge due to their intricate spatial arrangements and the weak magnetic field signatures they produce, and this has made their identification experimentally subtle. This has left their existence and underlying mechanisms a topic of intense debate. In this work, we uncover signatures compatible with loop currents: spin handedness-selective signals that surpass conventional dichroic, spin, and spin-dichroic responses. We observe this phenomenon in the kagome metal CsTi 3 ⁢Bi 5 and we call it the anomalous spin-optical helical effect. This effect arises from the coupling of light's helicity with spin-orbital electron correlations, thereby providing an indirect yet sensitive approach to probe loop-current–related electronic correlations in quantum materials. Our discovery not only enriches the debate surrounding loop currents but also offers new experimental strategies to exploit the electronic phases of quantum materials via light–matter interaction.

anomalous spin-optical helical effect↗
NASA NTRS1985

Acoustic Gaussian Far-Field Pattern

Gaussian profile achieved by using annular electrodes. Transducer constructed by deposting circularly symmetric metallic multielectrode array on 12.7 mm diameter X-cut quartz disk. Each electrode independently connected to impedance network optimized to produce Gaussian distribution with less than 2 percent error. Ultrasonic transducer produces far field beam with Gaussian spatial profile for materials evaluation applications.

Claus, R. O.↗
NASA NTRS1985

Structure of super-families

At present the study of nuclear interactions induced by cosmic rays is the unique source of information on the nuclear interactions in the energy region above 10 to the 15th power eV. The phenomena in this energy region are observed by air shower arrays or emulsion chambers installed at high mountain. An emulsion chamber is the pile of lead plates and photo-sensitive layers (nuclear emulsion plates and/or X-ray films) used to detect electron showers. High spatial resolution of photographic material used in the emulsion chamber enables the observation of the phenomena in detail, and recent experiments of emulsion chamber with large area are being carried out at high mountain altitudes by several groups in the world.

Yamashita, S.↗
NASA NTRS1993

Calibration of a synthetic aperture radiometer

Calibration algorithms for a synthetic aperture microwave radiometer are presented. The calibration is geared to Earth remote sensing applications, and is demonstrated on an airborne prototype of thinned array imager. Two approaches to the system calibration are presented; the first utilizes commonly available reference brightness temperature scenes, such as open water, and the second utilizes data collected on the antenna range. Both algorithms yield spatial response information which is cast in matrix form and inverted to obtain the image reconstruction formula. Experimental results are examined, and errors in some reconstructed images are linked to the present prototype antenna design. Algorithms for improving the synthesized antenna pattern side lobe performance are also presented. In one solution, the pattern efficiency is optimized by minimizing the pattern outside a defined beam. In another solution, the patterns are matched to a desired model pattern by the method of least squared errors. Both techniques offer an attractive alternative to aperture weighting.

Tanner, Alan B.↗
NASA NTRS1994

Coronal temperature, density, and magnetic field maps of a solar acitve region using the Owens Valley Solar Array

We present the first results of solar active region observations with the recently completed five-element Owens Valley Solar Array. On 1991 October 24, maps of Active Region AR 6891 were obtained at 22 frequencies from 1.2-7.0 GHz to provide brightness temperature spectra at each point. This is the first time that both high spatial and frequency-resolution brightness temperature spectra have been available over such a broad radio-frequency range. We find that over most of the region the spectra fall into one of the two well-defined categories: thermal free-free or thermal gyroresonance. In these cases, we use the spectra to deduce the spatial variation of physical parameters-electron temperature, column emission measure (intergral n(sup 2)(sub e) dl), and the coronal magnetic field strength-in and around the active region. Over a limited area of the region, the spectra resemble neither of the simple types, and alternative interpretations are required. The possibilties include the presence of fine structure that is unresolved at low frequencies; the presence of a small number of nonthermal electrons; or the presence of overlying, cooler 10(exp 6) K material which at low frequencies absorbs the hot (3 x 10(exp 6) K) thermal emission generated below.

Gary, Dale E.↗
NASA NTRS1996

Infrared Source For Testing Thermophotovoltaic Cells

Source of pulsed infrared radiation for testing arrays of thermophotovoltaic cells obtained by placing infrared band-pass filter in front of large-area pulsed solar simulator (LAPSS). Source provides infrared radiation within required infrared spectral region, at required intensity and approximate spatial uniformity, over minimum area of 4 by 4 inches (10 by 10 centimeters).

Lin, James J.↗
NASA NTRS2008

Shaping Diffraction-Grating Grooves to Optimize Efficiency

A method of shaping diffraction-grating grooves to optimize the spectral efficiency, spectral range, and image quality of a spectral imaging instrument is under development. The method is based on the use of an advanced design algorithm to determine the possibly complex shape of grooves needed to obtain a desired efficiency-versus-wavelength response (see figure). Then electron- beam fabrication techniques are used to realize the required groove shape. The method could be used, for example, to make the spectral efficiency of the grating in a given wavelength range proportional to the inverse of the spectral efficiency of a photodetector array so that the overall spectral efficiency of the combination of the grating and the photodetector array would be flat. The method has thus far been applied to one-dimensional gratings only, but in principle, it is also applicable to two-dimensional gratings. The algorithm involves calculations in the spatial-frequency domain. The spatial-frequency spectrum of a grating is represented as a diffraction-order spectral-peak-width function multiplied by an efficiency function for a single grating groove. This representation affords computational efficiency and accuracy by making it possible to consider only the response from one grating groove (one period of the grating), instead of from the whole grating area, in determining the response from the entire grating. This combination of efficiency and accuracy is crucial for future extensions of the algorithm to two-dimensional designs and to designs in which polarization must also be taken into account. The algorithm begins with the definition of target values of relative efficiency that represent the desired spectral response of the grating in certain spectral frequencies calculated from the diffraction order and wavelength. The grating period is divided into a number of cells - typically, 100. The phase contribution from each cell is determined from the phase of the incident electromagnetic wave and the height of the grating surface in the cell. The total contribution from all cells to each target value is then calculated. Then a method known to specialists as the optimum-rotation-angle method is used to adjust the height of each cell so that the total response from all cells is optimized. The computation is iterative and continues until the desired response is obtained. In the event that the desired response is unphysical, the algorithm nevertheless strives to generate a grating-grove profile for which the response approximates the desired one as closely as possible.

Backlund, John↗
NASA NTRS2008

Instrument Performance of GISMO, a 2 Millimeter TES Bolometer Camera used at the IRAM 30 m Telescope

In November of 2007 we demonstrated a monolithic Backshort-Under-Grid (BUG) 8x16 array in the field using our 2 mm wavelength imager GISMO (Goddard IRAM Superconducting 2 Millimeter Observer) at the IRAM 30 m telescope in Spain for astronomical observations. The 2 mm spectral range provides a unique terrestrial window enabling ground-based observations of the earliest active dusty galaxies in the universe and thereby allowing a better constraint on the star formation rate in these objects. The optical design incorporates a 100 mm diameter silicon lens cooled to 4 K, which provides the required fast beam yielding 0.9 lambda/D pixels. With this spatial sampling, GISMO will be very efficient at detecting sources serendipitously in large sky surveys, while the capability for diffraction limited imaging is preserved. The camera provides significantly greater detection sensitivity and mapping speed at this wavelength than has previously been possible. The instrument will fill in the spectral energy distribution of high redshift galaxies at the Rayleigh-Jeans part of the dust emission spectrum, even at the highest redshifts. Here1 will we present early results from our observing run with the first fielded BUG bolometer array. We have developed key technologies to enable highly versatile, kilopixel, infrared through millimeter wavelength bolometer arrays. The Backshort-Under-Grid (BUG) array consists of three components: 1) a transition-edge-sensor (TES) based bolometer array with background-limited sensitivity and high filling factor, 2) a quarter-wave reflective backshort grid providing high optical efficiency, and 3) a superconducting bump-bonded large format Superconducting Quantum Interference Device (SQUID) multiplexer readout. The array is described in more detail elsewhere (Allen et al., this conference). In November of 2007 we demonstrated a monolithic 8x 16 array with 2 mm-pitch detectors in the field using our 2 mm wavelength imager GISMO (Goddard IRAM Superconducting 2 Millimeter Observer) at the IRAM 30 m telescope in Spain for astronomical observations. The 2 mm spectral range provides a unique terrestrial window enabling ground-based observations of the earliest active dusty galaxies in the universe and thereby allowing a better constraint on the star formation rate in these objects. The optical design incorporates a 100 mm diameter silicon lens cooled to 4 K, which provides the required fast beam yielding 0.9 lambda1D pixels. With this spatial sampling, GISMO will be very efficient at detecting sources serendipitously in large sky surveys, while the capability for diffraction limited imaging is preserved. The camera provides significantly greater detection sensitivity and mapping speed at this wavelength than has previously been possible. The instrument will fill in the spectral energy distribution of high redshift galaxies at the Rayleigh-Jeans part of the dust emission spectrum, even at the highest redshifts. Here I will we present early results from our observing run with the first fielded BUG bolometer array.

Staguhn, Johannes↗
DOE OSTI2020

Nanostructures for Electrical Energy Storage (NEES) (2020 Final Technical Report)

Nanostructures for Electrical Energy Storage (NEES, www.efrc.umd.edu) was an Energy Frontier Research Center supported by the DOE Office of Science, Basic Energy Sciences, from 8/1/2009 to 7/31/2020. Led by the University of Maryland, NEES enjoyed extensive collaborations with its funded partners, including two DOE Laboratories and six universities. The NEES vision has been to reveal a set of scientific insights and design principles that can underpin a next-generation electrical energy storage approach, building on advances in nanoscale science and technology to achieve simultaneous high power and high energy over extended charge/discharge cycling. The vision is motivated by the recognition that scaling into the nano regime opens the door to new physical phenomena and that the tools enlisted in nanoscale research provide major new opportunities for the synthesis not only of materials at molecular scale but for structures at nano scale and above. NEES has translated this vision into its research program based on two observations. First, while the behavior of ions and electrons in electrolytes and in electrode materials is crucial to electrical energy storage (or more appropriately electrochemical energy storage), it is the transport of ion and electron charge between different structural components of a storage device that ultimately determine its performance. With it well recognized that the choice of electrode materials typically constrain ion transport kinetics as well as maximum ion concentration, the search for better electrode materials has been a primary driver of battery research. At the same time the synthesis of electrodes is typically based on aggregation of particles with varying size, shape, and orientation in the electrode. Together with the presence of additional materials to impart electrical conductivity and cohesion to the composite electrode, change in electrode materials is necessarily accompanied by structural changes at the nano/micro scale that are difficult to categorize and manage. From the beginning, NEES’ vision has been to create and study simpler, highly controlled spatial arrangements of known materials as battery components (electrodes, current collectors, and electrolyte) and to understand how design and structure above the molecular scale determines the energy storage performance available from known materials. Second, advances in nanoscience dramatically expanded the portfolio of synthesis methods, structural motifs, and new phenomena available for research. Some of these gave rapid access to new building blocks at the deep nanoscale (e.g., carbon nanotubes grown by self-assembly, nanoscale arrays formed by electrochemical self-alignment, monolayer films controlled by self-limiting reaction). Such advances served as the enabler for the NEES vision to be pursued experimentally through study of 3D structures created and controlled at the nano, micro, and meso scales. Here, we use meso as in the BES MESO Report, implying not only intermediate or varying length scales, but very much the way behavior is influenced by other factors including aggregation of nanocomponents at different densities and spatial configurations, statistical variations in the aggregates, hierarchical architectures in which they can be assembled, or local 3D configurations that result from the architectures. Over its life cycle, NEES has pursued two overarching goals: (1) to understand the scientific fundamentals of electrochemical storage from the nanoscale to the mesoscale; and (2) to create and learn from innovative, controlled, heterogeneous nanostructures, where such nanostructures can enable the first goal and serve as models for future paradigms in energy storage. Specific goals have included: Synthesize heterogeneous nanostructures comprised of multiple materials arranged in controlled fashion and characterize their behavior; Demonstrate and elucidate design principles for achieving simultaneous high power and high energy; Develop materials processes which enable precision control of thin layers and 3D structures; Investigate the impact of artificial interphases on electrode stability during ion insertion/deinsertion; Create dense arrays of nanostructures to understand how the architecture of these assemblies, along with nanostructure design, influences energy storage behavior at the mesoscale; Identify and understand the consequences of nanoconfinement and local inhomogeneities in 3D mesoscale arrays; Develop and apply computational models to stimulate, guide and interpret experiments.

25 ENERGY STORAGE↗
NASA NTRS2020

Measurements of few-mode fiber photonic lanterns in emulated atmospheric conditions for a low earth orbit space to ground optical communication receiver application

Photonic lanterns are being evaluated as a component of a scalable photon counting real-time optical ground receiver for space-to-ground photon-starved communication applications. The function of the lantern as a component of a receiver is to efficiently couple and deliver light from the atmospherically distorted focal spot formed behind a telescope to multiple small-core fiber-coupled single-element super-conducting nanowire detectors. This architecture solution is being compared to a multimode fiber coupled to a multi-element detector array. This paper presents a set of measurements that begins this comparison. This first set of measurements are a comparison of the throughput coupling loss at emulated atmospheric conditions for the case of a 60 cm diameter telescope receiving light from a low earth orbit satellite. The atmospheric conditions are numerically simulated at a range of turbulence levels using a beam propagation method and are physically emulated with a spatial light modulator. The results show that for the same number of output legs as the single-mode fiber lantern, the few-mode fiber lantern increases the power throughput up to 3.92 dB at the worst emulated atmospheric conditions tested of D/r(sub 0)=8.6. Furthermore, the coupling loss of the few-mode fiber lantern approaches the capability of a 30 micron graded index multimode fiber chosen for coupling to a 16 element detector array.

Tedder, Sarah A.↗
NASA NTRS2000

Discovery of Spatial and Spectral Structure in the X-Ray Emission from the Crab Nebula

The Chandra X-Ray Observatory observed the Crab Nebula and pulsar during orbital calibration. Zeroth-order images with the High-Energy Transmission Grating (HETG) readout by the Advanced Charge Coupled Devices (CCD) Imaging Spectrometer spectroscopy array (ACIS-S) show a striking richness of X-ray structure at a resolution comparable to that of the best ground-based visible-light observations. The HETG-ACIS-S images reveal, for the first time, an X-ray inner ring within the X-ray torus, the suggestion of a hollow-tube structure for the torus, and X-ray knots along the inner ring and (perhaps) along the inward extension of the X-ray jet. Although complicated by instrumental effects and the brightness of the Crab Nebula, the spectrometric analysis shows systematic variations of the X-ray spectrum throughout the nebula.

Weisskopf, Martin C.↗
DOE OSTI2023

Testing of fiber optic based sensors for advanced reactors in the Texas A&M University TRIGA reactor

An Optical Fiber Based Gamma Thermometer has been developed and tested at the Texas A&M University reactor as well as the Ohio State Research Reactor. This sensor technology provides temperature measurement of a thermal mass undergoing gamma heating, from which the gamma flux along the length of the sensor may be calculated. The gamma flux data from an array of OFBGTs could allow the determination of local power density within a nuclear reactor core in three dimensions. The design of the sensor makes use of optical fiber as a truly distributed temperature sensor with a spatial resolution less than 1mm and temperature accuracy of ±1°C. The testing program showed that the system provided the expected temperature data for each location. Overall, this sensor technology shows promise for current Light Water Reactors as well as advanced nuclear reactors by providing an unparalleled level of precision in reactor power measurement.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗