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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS2015

Propellant Feed System for Swirl-Coaxial Injection

A propellant feed system for swirl-coaxial injection of a liquid propellant includes a reservoir having a bottom plate and at least one tube originating in the bottom plate and extending therefrom. The tube has rectangular slits defined in and distributed tangentially and evenly about a portion of the tube that is disposed in the bottom plate. Drain holes are provided in the bottom plate and tunnels are defined in the bottom plate. Each tunnel fluidly couples one of the drain holes to a corresponding one of the rectangular slits. Each tunnel includes (i) a bend of at least 90.degree., and (ii) a straight portion leading to its corresponding rectangular slit wherein the straight portion is at least five times as long as a hydraulic diameter of the corresponding rectangular slit.

Reynolds, David Christopher↗
DOE OSTI2023

Ion beam profiling system and related methods

An ion beam profiling system include a beam profiling element, an ion sensitive element electrically isolated from the beam profiling element, an ion source configured to emit an ion beam at the beam profiling element and the ion sensitive element, and a current measuring device coupled to the ion sensitive element. The beam profiling element includes a plate of material having two parallel major surfaces, a first slit aperture extending through the plate of material and having a first longitudinal length extending in a direction parallel to the two parallel major surfaces, and a second slit aperture extending through the plate of material and having a second longitudinal length extending in a direction parallel to the two parallel major surfaces, wherein the first longitudinal length of the first slit aperture is perpendicular to the second longitudinal length of the second slit aperture.

Taylor, Chase N.↗
DOE OSTI2022

Residual Stress Measurements in Extreme Environments for Hazardous, Layered Specimens

In nuclear fuel plates of low-enriched U-10Mo (LEU) clad with aluminum by hot isostatic pressing (HIP), post-irradiation stresses arising during reactor shutdown are a major concern for safe reactor operations. Measurement of those residual stresses has not previously been possible because the high radioactivity of the plates requires handling only by remote manipulation in a hot cell. The incremental slitting method for measuring through-thickness stress profiles was modified, and a system for automated, remote operation was built and tested. Experimental modifications consisted of replacing electric-discharge machining (EDM) with a small end mill and strain-gauge measurements with cantilever displacement measurements. The inverse method used to calculate stresses was the pulse-regularization method modified to allow discontinuities across material interfaces. The new system was validated by comparing with conventional slitting on a depleted U-10Mo (DU) fuel plate. The new system was applied to two measurements each on six as-fabricated (pre-irradiation) LEU miniature fuel plates. Variations between the measurements at two locations in the same plate were strongly correlated with measured geometrical heterogeneity in the plate—a tilt in the fuel foil. Compressive stresses in the U-10Mo were shown to increase from 20 to 250 MPa as the ratio of aluminum thickness to U-10Mo thickness increased causing increased constraint during cooling. Faster cooling rates during processing also increased stress magnitudes. The measurements trends agreed with data in the literature from similar plates made with DU, which further validates the method. Because other methods are impractical in a hot cell, the modified slitting method is now poised for the first measurements of post-irradiation stresses.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Time-reversed Young’s experiment: Deterministic, diffractionless second-order interference effect

The classic Young’s double-slit experiment exhibits first-order interference, producing alternating bright and dark fringes shaped by the diffraction effect of the slits. In contrast, here we demonstrate that its time-reversed configuration generates an ideal, deterministic second-order ‘ghost’ interference pattern free from diffraction and first-order effects with the use of only a position-fixed detector. The pattern’s size is governed by the dimensions of the ‘effectively extended light source’ formed by point emitter(s). Beyond highlighting the nonreciprocal physics between the two configurations, this system unlocks a range of novel phenomena inaccessible in traditional double-slit experiments. These include fully programmable, digitized interference fringe formations and the ability to align the pattern plane with the source plane on the same side of the setup. Remarkably, our proposed experiment achieves these outcomes without relying on nonclassical correlations or quantum entanglement. Here, by restoring time-reversal symmetry and eliminating diffraction, our theoretical analysis reveals that this approach offers exciting potential for advancing optical imaging and sensing technologies with improved transverse and longitudinal phase-shift sensitivity and resolution limit beyond current limitations.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2026

How Silica Surface Chemistry Modulates Interfacial Water: Insights from Machine Learning Molecular Dynamics

Controlling water structure and dynamics at silica interfaces are central to a wide range of technologies, including protective oxide layers for solar water splitting and nanoporous membranes. In this work, we develop a machine learning interatomic potential, trained via active learning, to achieve ab initio accuracy for water confined between hydroxylated silica surfaces over a range of silanol coverages and slit widths. We find that partially hydroxylated surfaces (50 and 75% OH) support stronger water−surface hydrogen bonding and more extended interfacial density profiles than fully hydroxylated (100% OH) surfaces, indicating that increasing OH coverage does not necessarily strengthen interfacial hydrogenbond networks. Translational diffusion decreases approximately linearly with slit width and OH coverage, whereas rotational dynamics respond nonlinearly. In particular, at the smallest slit width of 5 Å, 75% OH coverage produces an enhanced local tetrahedral ordered interfacial network that strongly suppresses reorientation, while 100% coverage yields a crowded, disordered interfacial layer that also hinders rotation. In contrast, the 50% OH coverage is sufficiently sparse that it does not markedly alter water structure or dynamics under confinement. These results show that coupled control of pore size and surface chemistry enables nonlinear tuning of interfacial water structure and transport, providing a design strategy for optimizing porous silica for either enhanced interfacial stability and controlled reactivity or rapid and selective transport.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Adsorption Hysteresis Under Control: Tuning Host–Guest Interactions via a Genetic Algorithm

Mesoporous adsorbent materials offer a large volumetric capacity; however, cyclic adsorption/desorption processes in these systems often suffer from hysteresis and may require a significant pressure swing to access this capacity. To mitigate hysteresis, a proposed strategy is to include nucleation sites on the walls of the mesoporous material to facilitate droplet and bubble formation, lowering the free energy barriers to the respective phase transitions. It is unclear, however, what combination of adsorbate− adsorbent interactions and spatial patterning would be beneficial for a given application, considering that improvements to some sorption properties may come at the expense of other attributes. To understand these interconnected observables, we examine two model systems, planar-slit and cylindrical pores with tunable interaction sites, using GPU-accelerated transition matrix Monte Carlo simulations. The simulations provide a free energy map of the pressure−adsorption space in a matter of minutes, which we use to track adsorption isotherm characteristics as a function of adsorbent properties. We then leverage the rapid acquisition of simulation data to construct a genetic algorithm to iteratively modify interaction sites of the slit-pore wall to minimize the hysteresis of this system without sacrificing uptake. We find that the adsorption branch of the isotherm is easily modulated via the average host−guest interaction strength, but desorption is only adjustable if there is a suitable bubble nucleation site. Within the context of a slit-pore system, we identify relative interaction strengths and patch sizes required to gain control over both branches of the hysteresis loop.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Freestanding high-aspect-ratio gold masks for low-energy, phase-based x-ray microscopy

High-resolution, x-ray phase contrast microscopy, a key technique with promising potential in biomedical imaging and diagnostics, is based on narrow-slit high-aspect-ratio gold gratings. Here we present the development, fabrication details, and experimental testing of the freestanding 10 μm thick gold membrane masks with an array of 0.9–1.5 μm void slit apertures for a novel low-energy x-ray microscope. The overall mask size is 4 mm × 4 mm, with a grating pitch of 7.5 μm, 6.0–6.6 μm wide gold bars are supported by 3 μm wide crosslinks at 400 μm intervals. The fabrication process is based on gold electroplating into a silicon mold coated with various thin films to form a voltage barrier, plating base, and sacrificial layer, followed by the mold removal to obtain the freestanding gold membrane with void slit apertures. We discuss key aspects for the materials and processes, including gold structures homogeneity, residual stresses, and prevention of collapsing of the grid elements. We further demonstrate the possibility to obtain high-resolution, high contrast 2D images of biological samples using an incoherent, rotating anode x-ray tube.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2024

Nature of the diffuse emission sources in the H i supershell in the galaxy IC 1613

ABSTRACT We present a study of the nearby low-metallicity dwarf galaxy IC 1613, focusing on the search for massive stars and related feedback processes, as well as for faint supernova remnants (SNR) in late stages of evolution. We obtained the deepest images of IC 1613 in the narrow-band H α, He ii and [S ii] emission lines and new long-slit spectroscopy observations using several facilities (6-m BTA, 2.5m SAI MSU, and 150RTT telescopes), in combination with the multiwavelength archival data from MUSE/VLT, VLA, XMM–Newton, and Swift/XRT. Our deep narrow-band photometry identifies several faint shells in the galaxy, and we further investigate their physical characteristics with the new long-slit spectroscopy observations and the archival multiwavelength data. Based on energy balance calculations and assumptions about their possible nature, we propose that one of the shells is a possible remnant of a supernova explosion. We study five out of eight Wolf–Rayet (WR) star candidates previously published for this galaxy using the He ii emission line mapping, MUSE/VLT archival spectra, and new long-slit spectra. Our analysis discards the considered WR candidates and finds no new ones. We found P Cyg profiles in H α line in two stars, which we classify as Luminous Blue Variable (LBV) star candidates. Overall, the galaxy IC 1613 may have a lower rate of WR star formation than previously suggested.

Astronomy & Astrophysics↗
DOE OSTI2020

GoldSim E-Area Low-Level Waste Lacility Vadose Zone Model Benchmarking

This report documents the development and benchmarking of the E-Area Low-Level Waste Facility (ELLWF) GoldSim Engineered and Slit Trench (ET and ST) vadose zone models. Subsequent activities (beyond the scope of this effort) will couple the GoldSim-based vadose zone models to the GoldSim aquifer model, with the intent of performing stochastic analyses that couple all pertinent fate and transport processes from the ground surface up to the 100-m Point of Assessment (POA). The benchmarking presented within this report focuses on the Slit Trench 06 (ST06) bydrostratigraphic location that resides within the center set of slit trenches. These GoldSim-based vadose zone models are generic models capable of being benchmarked to any of the other trench locations within E-Area.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1970

Investigation of an Optimum Detection Scheme for a Star-Field Mapping System

An investigation was made to determine the optimum detection scheme for a star-field mapping system that uses coded detection resulting from starlight shining through specially arranged multiple slits of a reticle. The computer solution of equations derived from a theoretical model showed that the greatest probability of detection for a given star and background intensity occurred with the use of a single transparent slit. However, use of multiple slits improved the system's ability to reject the detection of undesirable lower intensity stars, but only by decreasing the probability of detection for lower intensity stars to be mapped. Also, it was found that the coding arrangement affected the root-mean-square star-position error and that detection is possible with error in the system's detected spin rate, though at a reduced probability.

Aldridge, M. D.↗
NASA NTRS1975

Errors in Hadamard spectroscopy or imaging caused by imperfect masks

An analysis is given of the errors in Hadamard spectroscopy that are caused by transparent slits in the mask being systematically wider or else narrower than they should be. It is shown that if the input spectrum consists of a single line, the distorted spectrum that is actually calculated consists of this line, plus four small blips. When the transparent slits are too wide, these blips are of equal height and the same sign, one pair surrounding the line, and another pair displaced a certain distance from it. When the slits are too narrow, the displaced blips have the same amplitude but are negative.

Tai, M. H.↗
NASA NTRS1975

Semiperiodic variations in CO2 abundance on Venus

Tests of the uniqueness of periodicity in the strength of the P branch (P2-P38) of the 8689 A CO2 band on Venus are described. It was found that the observed 4-day periodicity was not unique. The periodicity indicated an increasing asymmetry between the northern and southern hemispheres with approach to inferior conjunction or with increasing phase angle. When the slit positions of the various scans were referred to the planet or atmospheric equator rather than to the intensity equator, at inferior conjunction, the slit positions having a factor of two greater CO2 abundance or line strength were over the polar latitudes of the atmosphere. Similarly, the lower-abundance slit positions were over the equatorial latitudes of the atmosphere. It is thus concluded that the level of line formation must be lower over polar latitudes than over equatorial regions.

Barker, E. S.↗
NASA NTRS1975

Errors in Hadamard spectroscopy or imaging caused by imperfect masks

An analysis is given of the errors in Hadamard spectroscopy that are caused by transparent slits in the mask being systematically wider or narrower than they should be. It is shown that if the input spectrum consists of a single line, the distorted spectrum that is actually calculated consists of this line plus four small blips. When the transparent slits are too wide, these blips are of equal height and the same sign with one pair surrounding the line and another pair 5isplaced a certain distance from it. When the slits are too narrow, the displaced blips have the same amplitude, but are negative. The response to an arbitrary input spectrum is then determined from this. The same method of analysis may also be used to handle other types of errors.

Tai, M. H.↗
NASA NTRS1985

Improved Ellipsoidal Radiation Furnace

Spherical reflector around heat source increases efficiency and minimizes power requirements. Furnace consists of ellipsoid with point heat source, at one focus and sample heated at other focus. Spherical reflector with circular slit surrounds heat source. All radiation not passing through circular slit in spherical reflector reflected back to lamp. Radiation passing through spherical slit focused by ellipsoid surface onto sample. Arrangement uses heat efficiently, reduces waste heat generation and permits full view of specimen.

Ethridge, E. C.↗
NASA NTRS1986

Inexpensive Masks for Film Deposition

Sputtered sprayed lines less than 2 millimeters wide made by superimposing masks with partially overlapping openings. Slits first cut in masks by stamping or other economical process. Masks superimposed so slits define new openings narrower than original slits.

Conley, W. R.↗
NASA NTRS1986

Hall station and camera system operation and maintenance manual

The major components of the Hall station and camera system are described. The Hall film record of an event provides the time of flight of the projectile between the slits. A time mark generator is used to supply extremely short pulses of light at a known frequency. These pulses of light are used to produce timing marks on the edge of the film. Comparison of these marks with the spacing of the projectile images provides the information necessary to determine the time of flight of the projectile. Since the slits are installed with a known separation distance, calculation of the velocity of any object passing both slits is a simple matter.

Piekutowski, A. J.↗
NASA NTRS1985

Limb-atmospheric infrared spectrum observed on the satellite Ohzora

The Institute of Space and Astronautical Science (ISAS) launched the 9th scientific satellite Ohzora at 17:00 JST on February 14, 1984. This satellite bears the spectrometer, which measures the infrared spectrum of the solar radiation passing the limb atmosphere in the wavelength region of 2 to 10 m. The spectrometer is based on multichannel spectroscopy by using image sensors. Since the wavelength is scanned electronically, it can measure the spectrum unaffected by the satellite motion. A definite axis, i.e., the Z-axis of the satellite, which coincides to the optical axis of the spectrometer, is controlled to the direction of the Sun, and the finer control to introduce the solar light into the spectrometer is made with a 2-axes-controlled mirror. This solar tracking equipment is derived fast enough to measure the spectra in a moment after sunrise. The solar light introduced into the spectrometer is focused on the slits of the monochromators (f=100mm). For better altitude resolution, the horizontal slit is also used with the vertical slit, which is used for the separation of the dispersion. The dispersion light is detected with the pyroelectric array sensors. To obtain maximum dynamic range and spectral resolution, the three-stage polychromator is used.

Matsuzaki, A.↗
NASA NTRS1986

HRTS results from Spacelab 2

The High Resolution Telescope and Spectrograph (HRTS) instrument flew on the Spacelab 2 mission and consisted of a 30-cm Gregorian telescope, a slit spectrograph covering the 1190-1680 A region with 0.05-A spectral resolution, a broadband (90 A FWHM) spectroheliograph tuned to 1550 A, and an H-alpha filter system. The spectrograph slit was 920 arcsec, approximately in length. Subarcsecond spatial resolution along the slit is possible, but because of jitter in the Spacelab Instrument Pointing System, good exposures actually achieved 1-2 arcsec resolution.

Brueckner, G. E.↗