Search NASA⌕ Search

SEARCH · Search NASA

Results for “CH2O laser-induced fluorescence”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

365 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

GOPEX at the Starfire Optical Range

The Starfire Optical Range successfully conducted laser upink experiments to the Galileo spacecraft during the early morning hours of December 9, 10, 11, and 12, 1992, when the spacecraft was at ranges between 700,000 and 3 million km from Earth. Analysts at JPL have reported as many as 79 pulse detections by the spacecraft. The best weather conditions occurred on the second night when 37 pulses were detected with as many as five on one frame. Signal levels at the spacecraft generally agree with predictions.

R Q Fugate↗
NASA NTRSDate not supplied

Preliminary Findings of the Experimental Development Unit Cold Flow Test for a Generation Zero Nuclear Propulsion Engine

Nuclear thermal propulsion (NTP) technology will greatly benefit human travel to Mars by significantly shortening transit times, improving crew safety, and providing more mission flexibility than traditional chemical rockets. As part of DRACO follow-on work to develop, build, and fly a generation zero NTP engine, a full scale flight-like experimental design unit (EDU) reactor was constructed to collect sufficient on-ground performance data to characterize flow induced vibrations (FIV) of critical reactor structures/components, inform development of the engine and reactor control algorithm, and collect pressure drop and flow distribution data across the reactor. The fluid conditions for the test program were designed to achieve system responses equivalent to that of an operational engine through all phases of engine operation including reactor startup, mainstage operation, reactor shutdown, and reactor cooldown. Over 100 tests were executed, flowing either GN2 or GHe through the EDU at varying flow rates and pressures. This experiment provided early validation of flow behavior and vibration risks before nuclear testing, boosted critical subsystem TRLs, informed design iterations, and reduced future test costs. The steady-state flow parameters for the experiment were modeled in Ansys Thermal Desktop, allowing rapid tuning and experiment-informed updates to a flight-like test matrix. The EDU dynamic environment was characterized with accelerometers, strain gauges, and high-frequency pressure transducers all sampled at 20 kHz. While many narrow-band oscillations were identified, no significant FIV occurred; the reactor structural responses tend to be enveloped by typical launch vehicle ascent vibration environments (defined up to 2 kHz), although significant energy is also present at higher frequencies.

Flow Induced Vibration↗
DOE OSTI2026

Spin‐Polarized Interfaces Redirect CO 2 Reduction From CO to Formate

Achieving high product selectivity in electrocatalytic carbon dioxide reduction (CO 2 RR) remains a critical challenge due to competition between multiple proton-coupled electron-transfer pathways on catalyst surfaces. Meanwhile, chirality-induced spin selectivity (CISS), which enables spin-polarized electron transport through chiral interfaces, has recently emerged as a promising strategy to modulate interfacial electrochemical reactions. Although the CISS effect has been shown to enhance selectivity and efficiency in the spin-sensitive oxygen evolution reaction (OER), its role in regulating CO 2 RR pathways and in stabilizing intermediates remains largely unexplored. Here, chiral molecules (R- and S-1,1′-bi-2-naphthyl-2,2′-diyl hydrogen phosphate, BNP) were integrated with SnO 2 to construct chiral-modified catalysts (R-BNP/SnO 2 and S-BNP/SnO 2 ). Compared with bare SnO 2 and racemic BNP-modified SnO 2 (Rac-BNP/SnO 2 ), the chiral catalysts exhibited a pronounced shift in product selectivity from CO toward formate production. Importantly, in-situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) reveals that the chiral interface selectively stabilizes the O-bound *OCHO intermediate associated with the formate pathway and modulates interfacial water structure and hydrogen-bonding dynamics. These findings demonstrate that spin-polarized interfacial electron transfer can regulate CO 2 RR pathway selectivity by modulating the stabilization of key intermediates. More broadly, this work establishes chiral spin-selective interfaces as a new strategy for regulating competitive electrocatalytic reaction pathways.

14 SOLAR ENERGY↗
NASA NTRS2020

The Slow Demise of the Long-Lived Sn 2005ip

The Type IIn supernova (SN IIn) 2005ip is one of the most well-studied and long-lasting examples of an SN interacting with its circumstellar environment. The optical light curve plateaued at a nearly constant level for more than five years, suggesting ongoing shock interaction with an extended and clumpy circumstellar medium (CSM). Here, we present continued observations of the SN from ∼1000 to 5000 d post-explosion at all wavelengths, including X-ray, ultraviolet, near-infrared (NIR), and mid-infrared. The UV spectra probe the pre-explosion mass loss and show evidence for CNO processing. From the bolometric light curve, we find that the total radiated energy is in excess of 10 50 erg, the progenitor star’s pre-explosion mass-loss rate was >~ 1 × 10 −2 Mꙩ yr −1 , and the total mass lost shortly before explosion was >~1Mꙩ, though the mass lost could have been considerably larger depending on the efficiency for the conversion of kinetic energy to radiation. The ultraviolet through NIR spectrum is characterized by two high-density components, one with narrow high-ionization lines, and one with broader low-ionization H I, He I, [OI], Mg II, and Fe II lines. The rich Fe II spectrum is strongly affected by Lyα fluorescence, consistent with spectral modelling. Both the Balmer and He I lines indicate a decreasing CSM density during the late interaction period. We find similarities to SN 1988Z, which shows a comparable change in spectrum at around the same time during its very slow decline. These results suggest that, at long last, the shock interaction in SN 2005ip may finally be on the decline.

stars↗
NASA NTRS1977

Lunar Elemental Analysis Obtained From the Apollo Gamma-Ray and X-Ray Remote Sensing Experiment

Gamma-ray and X-ray spectrometers carried in the Service Modules of the Apollo 15 and Apollo 16 spacecraft were employed for compositional mapping of the lunar surface. The measurements involved the observation of the intensity and characteristic energy distribution of gamma rays and X-rays emitted from the lunar surface. A large-scale compositional map of over 10 percent of the lunar surface was obtained from an analysis of the observed spectra. The Apollo 15 flight was at a lunar orbital inclination of 29 degrees as compared with a 9-degree inclination of the Apollo 16 flight; thus, the projected ground track of the Apollo 15 flight covered a larger projected surface area than that of the Apollo 16 flight. The objective of the X-ray experiment was to measure the K spectral lines from Mg, Al, and Si. Spectra were obtained and the data were reduced to Al/Si and Mg/Si intensity ratios and ultimately to chemical ratios. Analyses of the results have indicated (1) that the Al/Si ratios are highest in the lunar highlands and considerably lower in the maria, and (2) that the Mg/Si concentrations generally show the opposite relationship. There is a tendency for the Al/Si values to increase from the western mare areas to the eastern limb highlands. There are distinct chemical contrasts between such features: as the small mare basins and the highland rims. The objective of the gamma-ray experiment was to measure the natural and cosmic-ray-induced activity emission spectrum. At this time, the elemental abundances for Th, U, K, Fe, Ti, Si, and O have been determined over a number of major lunar regions. Regions of relatively high natural radioactivity were found in the Mare Imbrium and Oceanus Procellarum regions. High spots of natural radioactivity were also found south of Fra Mauro; somewhat southwest of Archimedes, and south of Aristarchus. An enhanced region of natural radioactivity was found around Van de Graaff on the far side of tile Moon. In regions other than Mare Imbrium and Oceanus Procellarum, an anticorrelation between natural radioactivity and lunar elevation, as determined from the Apollo laser, altimeter, has been found. From the combined results of the gamma-ray and X-ray spectrometer experiments almost complete information concerning the major element composition of over 10 percent of the lunar surface has been obtained. Distributions have also been mapped for K, Th, and Ti. Interesting correlations between lunar topography and magnetic and gravitational properties have been found.

J I Trombka↗
DOE OSTI2026

Iron surface corrosion in supercritical CO2 at atomic scale investigated by molecular dynamics simulations

Understanding the corrosion behavior of steels in supercritical carbon dioxide (S-CO2) is essential for ensuring the safe application of S-CO2 as a heat-transfer fluid in high-temperature energy systems, including advanced nuclear reactors. In this work, molecular dynamics (MD) simulations using ReaxFF potential are performed to explore the atomic-scale corrosion mechanisms of body-centered cubic iron (BCC-Fe) in S-CO2. The results show that CO2 molecules in S-CO2 decompose at the Fe surface, generating free C and O atoms that form Fe-C and Fe-O bonds and subsequently produce oxides and carbides. Concurrently, Fe atoms dissolve from the surface and diffuse into the S-CO2 region, resulting in interdiffusion of Fe, C and O atoms at the interface. The corrosion-layer thickness calculations show that high pressure and temperature induced by S-CO2 have stronger effects than surface orientation on the corrosion process. In addition, surface Fe atoms undergo substantial displacement under S-CO2 exposure, further accelerating corrosion. When a radiation-induced void is introduced near the Fe surface, the corrosion is enhanced. The void-matrix interface expands the reaction surface area and simultaneously induces corrosion reactions inside the bulk, resulting in a deeper penetration of C and O and thicker corrosion layers. All these results indicate that high-temperature, high-pressure and radiation-induced voids can seriously affect the corrosion of Fe in S-CO2, and must be considered to better use S-CO2 in nuclear facilities.

Li, Wenhua↗
NASA NTRS1993

An Overview of the Galileo Optical Experiment (GOPEX)

Uplink optical communication to a deep-space vehicle was demonstrated. In the Galileo Optical Experiment (GOPEX), optical transmissions were beamed to the Galileo spacecraft by Earth-based transmitters at the Table Mountain Facility (TMF), California, and Starfire Optical Range (SOR), New Mexico. The demonstration took place over an eight-day period (9 Dec. through 16 Dec. 1992) as Galileo receded from Earth on its way to Jupiter, and covered ranges from 1-6 million km. At 6 million km (15 times the Earth-Moon distance), the laser beam transmitted from TMF eight days after Earth flyby covered the longest known range for transmission and detection.

K E Wilson↗
NASA NTRS1993

Telescope Pointing for GOPEX

In order for photons emitted by the GOPEX lasers to "be detected by Galileo's camera, the telescopes at Table Mountain Observatory and Starfire Optical Range had to be pointed in the right direction within a tolerance less than the beam divergence. At both sites nearby stars were used as pointing references. The technical challenge was to ensure that the transmission direction and the star positions were specified in exactly the same coordinate system; given this assurance, neither the uncertainty in the star catalog positions nor the difficulty in offset pointing was expected to exceed the pointing error budget. The correctness of the pointing scheme was verified by the success of GOPEX.

W M Owen, Jr↗
NASA NTRS2026

Gateway Element and Payload Materials Outgassing Analyses: HALO, HERMES, and ERSA

Gateway was intended to be humanity’s first space station around the Moon, but its development has been paused as the National Aeronautics and Space Administration (NASA) shifts focus to achieving the United States’ National Space Policy goals. Instead of an orbiting lunar outpost, NASA will now pursue the development of a lunar surface base to support a sustained human presence on the Moon. Before the program’s pause, Gateway’s Induced Environments team worked to ensure payloads and elements (i.e., modules) complied with induced environment requirements. Methods developed and insights gained from this work will have applicability to NASA’s Moon Base and the potential repurposing of Gateway elements and payloads, as well as to induced environments modeling for future space stations. The Gateway program’s induced environment included molecular contamination, electric thruster plume sputter and redeposition, and lunar dust transfer from the Human Landing System (HLS). Primary sources of external molecular contamination included materials outgassing, chemical thruster plume contamination, and vacuum venting. The focus of this paper will be on element- and payload-level materials outgassing analyses performed for Gateway Configuration 1, extending the previously-developed framework for Gateway system-level external molecular contamination modeling. Gateway Configuration 1 consisted of the Power and Propulsion Element (PPE) and the Habitation and Logistics Outpost (HALO). It also included payloads like the European Radiation Sensor Array (ERSA) attached to PPE and the Heliophysics Environmental and Radiation Measurement Experiment Suite (HERMES) attached to HALO. The element- and payload-level analyses to be introduced in this paper for HALO, HERMES, and ERSA enabled high-fidelity descriptions of Gateway’s external molecular contamination environment. Approaches to geometric modeling, meshing, outgassing rate assignment, molecular transport modeling, and analysis methodology will be presented. Element and payload contaminant deposition onto sensitive Gateway receiver surfaces will be summarized and results compared to induced environment requirements. While these results incorporate refinements made over the course of the program, they were not intended to be final. Therefore, modeling assumptions and inputs, potential improvements, and lessons-learned will be documented to inform future work on Moon Base, repurposed elements and payloads, and other space stations.

Gateway↗
DOE OSTI2026

Theory of stimulated and spontaneous axion scattering.

We present a theory for nonlinear, resonant excitation of dynamical axions by counterpropagating electromagnetic waves in materials that break both 𝒫 and 𝒯 symmetries. We show that dynamical axions can mediate an exponential growth in the amplitude of the lower frequency (Stokes) beam. We also discuss spontaneous generation of a counterpropagating Stokes mode, enabled by resonant amplification of quantum and thermal fluctuations in the presence of a single pump laser. Remarkably, the amplification can be orders of magnitude larger than that obtained via stimulated Brillouin and Raman scattering processes, and can be modulated with the application of external magnetic fields, making stimulated axion scattering promising for optoelectronics applications.

Smith, M.↗
NASA NTRS1989

Overview of the Center for Advanced Space Propulsion

The mission of the Center for Advanced Space Propulsion (CASP), a Center for the Commercial Development of Space (CCDS), is to strengthen U.S. competitiveness in space technology, foster cooperative research with industry and government, assist industry in developing commercial products and services, and perform research in advanced space propulsion. Current areas of focus are (1) advanced chemical propulsion, including high area ratio nozzle performance, variable thrust engine performance, and spray combustion stability; (2) artificial intelligence propulsion applications, including health monitoring of rocket engines, fault pattern detection and diagnosis, and intelligent hypertext applications; (3) microgravity fluid management, including liquid storage and transfer, a subscale orbital fluid transfer experiment, and helical, two-phase flow; (4) electric propulsion, including magnetic annular arc thruster, ion thrustor, and electrostatic plasma accelerator; and (5) laser materials processing.

George W Garrison↗
NASA NTRS1993

Calibration of the Receiver Channel for the GOPEX Precursor Experiments

Calibration measurements for the cooled (253 K) photomultiplier tube (PMT) detector, used on the receiver channel of the transmit/receive (T/R) switch for GOPEX, were conducted in the laboratory. A pulsed frequency-doubled neodymium:yttrium-aluminum-garnet (Nd:YAG) laser was used to direct 532-mn light on the PMT. By monitoring the energy per pulse of the light incident on the PMT, the minimum number of photons detected could be determined. These results agreed with the photon flux back-calculated from the PMT output waveform. Approximately 700 incident photons arriving during a temporal pulse width of approximately 65 nsec were detected with a signal-to-noise ratio (SNR) of approximately 1. Other receiver channel characteristics, such as PMT dark currents, optical transmission, and interference filter sensitivity to angle of light incidence, were also measured.

A Biswas↗
DOE OSTI2026

Crustal Deformation and Gravitational Effects From Dynamic Ocean Mass Redistribution Impact Projected Sea‐Level Change

As the climate warms, associated changes in ocean dynamics will redistribute sea‐water mass within the ocean, contributing to relative sea‐level change. This mass redistribution will cause additional sea‐level changes due to gravitational self‐attraction, deformation of the solid Earth, and shifts in the Earth's rotation axis (GRD), which are not incorporated in sea‐level projections. Using CMIP6 climate model output, we quantify relative sea‐level changes induced by GRD from ocean‐dynamic mass loading through 2100. These effects act to amplify projected ocean‐dynamic sea‐level patterns, causing sea‐level rise in coastal regions, particularly along wide continental shelves and at high latitudes. On average, the magnitude of such GRD‐induced sea‐level change is equivalent to ∼15% of the signal due to dynamic ocean mass redistribution. Although our results show substantial inter‐model spread, they reveal that GRD‐induced relative sea‐level changes from ocean mass redistribution represent a non‐negligible component of regional sea‐level change and should be considered in projections.

58 GEOSCIENCES↗
DOE OSTI2025

Keldysh tuning of photoluminescence in a lead halide perovskite crystal

In 1964, Keldysh laid the groundwork for strong-field physics in atomic, molecular, and solid-state systems by delineating a ubiquitous transition from multiphoton absorption to quantum electron tunneling under intense AC driving forces. While both processes in semiconductors can generate carriers and result in photon emission through electron-hole recombination, the low quantum yields in most materials have hindered direct observation of the Keldysh crossover. Leveraging the large quantum yields of photoluminescence in lead halide perovskites, we show that we can not only induce bright light emission from extreme sub-bandgap light excitation but also distinguish between photon-induced and electric-field-induced processes. Our results are rationalized by the Landau-Dykhne formalism, providing insights into the non-equilibrium dynamics of strong-field light-matter interactions. These findings open new avenues for light upconversion and sub-bandgap photon detection, highlighting the potential of lead halide perovskites in advanced optoelectronic applications.

FOS: Physical sciences↗
NASA NTRSDate not supplied

Evaluations of Additively Manufactured Superalloy Lattice Blocks

Cast lattice block structures made up of high-temperature superalloys were previously shown to offer advantages in density, efficiency, and tailored properties. However, inconsistencies in casting die-fill, composition, and microstructure were identified as persistent issues with the casting process path. Three candidate lattice designs were screened through additive manufacturing of a superalloy. Laser powder bed fusion was applied with superalloy powder to produce lattice blocks for three-dimensional octahedral unit-cell designs of three heights. Properties of the structural designs versus additively manufactured lattices were compared, including structural dimensions, densities, defects, grain structures, crystallographic texture, and surface residual stresses. Findings indicate this concept could produce useful superalloy structures for high-temperature-capable static components requiring tailored density, and thermophysical and mechanical properties.

superalloy↗
NASA NTRS1992

Degradation of optical components in a space environment

The objective of the Phillips Laboratory (PL) Long Duration Exposure Facility (LDEF) experiment is to determine the adverse effects of the natural space environment on laser optical component and coating materials. The LDEF experiment provides a unique opportunity for the study of optical material response to an extended low earth orbit space exposure. The PL samples consist of 10 sets of the six materials each. The materials are uncoated fused silica, magnesium fluoride coated fused silica, uncoated molybdenum, molybdenum coated with chromium, silver and thorium fluoride, diamond turned copper, and diamond turned nickel plated copper. Performance degradation will be correlated to establish trends between sample location, duration of exposure, atomic oxygen exposure and other space environmental conditions. This paper discusses the results of the tests thus far performed on the LDEF samples and the plans for the future.

Linda L. Dehainaut↗
DOE OSTI2026

A simplified di-homodyne transient grating spectroscopy system utilizing polarization

Here, a modification to the di-homodyne transient grating spectroscopy optical arrangement is presented that removes the need to individually align two spatially separated probe laser beams. This work details the novel application of a single probe beam that utilizes birefringent materials to produce two optically homodyned signals with a relative phase shift of π radians. This arrangement effectively simplifies the alignment to one probe beam and removes the relative phase shift ambiguity between each homodyned signal. Several example measurements for tungsten, titanium, molybdenum, and silicon are shown to illustrate the utility of the new optical system.

Simmonds, M. J. [Univ. of California, San Diego, C↗
NASA NTRS1980

NASA/Marshall's lithium battery applications

A general lithium battery is described and a summary of lithium battery applications is presented. Four aspects of a particular lithium battery, the inducement environmental contamination monitoring battery, are discussed-design and construction details, thermal vacuum tests, projection tests, and acceptance tests.

Paschal, L. E.↗