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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 865 records · Page 48
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

A review of Sb 2 Se 3 photovoltaic absorber materials and thin-film solar cells

Energy generated from environmentally friendly, cost-effective solar cells is a key aspect for developing a clean renewable-energy economy. Non-toxic and Earth-abundant materials with high absorption coefficient (>10 5 cm -1 ) and optimal bandgap (1-1.5 eV) have received great attention as photovoltaic (PV) absorber layers during the last few decades. Among them, antimony selenide (Sb 2 Se 3 ) has been a promising PV absorber, with steadily increasing power-conversion efficiency (PCE) compared to other emerging compounds. Very recent studies showed that high-quality ZnO:Al/ZnO/CdS/TiO 2 /Sb 2 Se 3 /MoSe 2 /Mo devices with PCE of 9.2% can be fabricated using cost-effective novel compounds. Considering these recent advances, this article provides an overview of the material properties of Sb2Se3 thin films and the recent progress made with Sb 2 Se 3 -based solar cells. Furthermore, analysis of Sb 2 Se 3 -based thin-film solar cells has also shown that the devices have relatively good light management due to their suitable bandgap and high absorption coefficient, whereas carrier management, i.e. collection efficiency of photo-generated carriers, needs significant improvement. Overall, this study provides background knowledge on material properties and device performance and suggests main research directions to overcome the limiting factors of solar cell performance.

14 SOLAR ENERGY↗
DOE OSTI2025

Crack mitigation and wear performance of high-strength steel coatings deposited by high-speed laser cladding

This article investigates the fabrication of defect-free Rockit® 606, a high‑carbon, vanadium- and chromium-enriched precipitation-hardening martensitic steel coating, using high-speed laser cladding (HSLC). Compared to conventional laser cladding, HSLC offers higher deposition efficiency, improved coating quality, minimal thermal distortion, and a reduced heat-affected zone. Various HSLC parameters—including laser power, travel speed, powder feed rate, and overlap distance—were optimized to achieve superior coating properties. Microstructural analysis revealed solidification cracks in coatings deposited on carburized steel, regardless of processing parameters. However, preheating the substrate to 250 °C effectively eliminated cracking by reducing thermal gradients. The coatings exhibited a columnar dendritic microstructure, with coarser dendrites near the substrate and finer dendrites towards the surface. Hardness measurements confirmed that all coatings significantly exceeded the industry-specified threshold of 60 HRC, with preheating having minimal effect on overall hardness distribution. Reciprocating sliding wear tests demonstrated a substantial improvement in wear resistance for the defect-free HSLC coatings compared to baseline carburized steel. These findings underscore the potential of HSLC for producing high-performance, wear-resistant coatings suitable for industrial applications.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Molecular Characterization of Organophosphorus Compounds in Wildfire Smoke Using 21-T Fourier Transform-Ion Cyclotron Resonance Mass Spectrometry

Here, we present a detailed molecular characterization of organophosphorus compounds in ambient organic aerosol influenced by wildfire smoke. Biomass burning organic aerosol (BBOA) is an important source of phosphorus (P) to surface waters, where even a small imbalance in the P flux can lead to substantial effects on water quality, such as eutrophication, algal blooms, and oxygen depletion. We aimed to exploit the ultrahigh resolving power, mass accuracy, and sensitivity of Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS) to explore the molecular composition of an ambient BBOA sample collected downwind of Pacific Northwest wildfires. The 21-T FT-ICR MS yielded 10533 distinct formulae, which included molecular species comprising C, H, O, and P with or without N, i.e., organophosphorus compounds that have long been quantified in wildfire smoke but have not yet been characterized at the molecular level. The lack of detailed molecular characterization of organophosphorus compounds in BBOA is primarily due to their inherently low concentrations in aerosols and poor ionization efficiency in complex mixtures. We demonstrate that the exceptional sensitivity of the 21-T FT-ICR MS allows qualitative analysis of a previously uncharacterized fraction of BBOA without its selective concentration from the organic matrix, exemplifying the need for ultrahigh-resolution tools for a more detailed and accurate molecular depiction of such complex mixtures.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Performance of Oak Ridge National Laboratory spallation neutron source proton power upgrade cavities and cryomodule production

The Proton Power Upgrade initiative at Oak Ridge National Lab’s Spallation Neutron Source aims to greatly boost the capability of proton beam power. This upgrade involves the integration of seven additional cryomodules, each housing four six-cell high-beta ( β = 0.81 ) superconducting radio frequency cavities. These cavities, manufactured and processed by Research Instruments in Germany, underwent meticulous treatment, including electropolishing as the bulk and final vital step. Upon delivery to Jefferson Lab, a total of 28 cavities for seven cryomodules, along with an additional four cavities for a spare cryomodule, underwent thorough vertical qualification tests, meeting the required specifications. Following cavity tanking and subsequent rf testing, the assembly of eight cryomodules was successfully executed, with all 32 cavities demonstrating compliance with acceptance criteria. The transportation of the cryomodule to SNS for high-power testing in the tunnel yielded exceptional results. Notably, the performance surpassed specifications, in terms of quality factor and accelerating gradient. Published by the American Physical Society 2024

43 PARTICLE ACCELERATORS↗
DOE OSTI2026

High speed laser-induced refractive index change in ophthalmic HEMA hydrogel using a line focus

Laser-induced refractive index change (LIRIC) techniques typically focus femtosecond laser pulses to a tight spot to achieve the high intensities required to alter ophthalmic materials. A line-focus implementation using 800 nm pulses at 1 kHz repetition rate has been shown to greatly increase the effective writing speed of the process, but the high pulse energies used led to nonlinear propagation effects, presenting challenges for the fabrication of ophthalmic correctors. By taking advantage of the lower effective order of multiphoton absorption for 514 nm pulses, power levels may be reduced, allowing overlapped pulse writing. We demonstrate that this allows high-quality phase bars and devices to be made at high speeds.

Manning, Zachary A. [University of Rochester, NY (↗
DOE OSTI2022

Evaluating the Effects of Nitrogen Doping and Oxygen Doping on SRF Cavity Performance

Superconducting radiofrequency (SRF) cavities are resonators with extremely low surface resistance that enable accelerating cavities to have extremely high quality factors (Q₀). High Q₀ decreases the capital required to keep the accelerators cold by reducing power loss. The performance of SRF cavities is largely governed by the surface composition of the first §I{100}{nm} of the cavity surface. Impurities such as oxygen and nitrogen have been observed to yield high Q₀, but their precise roles are still being studied. Here, we compare the performance of cavities doped with nitrogen and oxygen in terms of surface composition and heating behavior with field. A simulation of the diffusion of oxygen into the bulk of the cavity was built using COMSOL Multiphysics software. Simulated results were compared to the actual surface composition of the cavities as determined from secondary ion mass spectrometry analysis. Understanding how these impurities affects performance allows us to have further insight into the underlying mechanisms that enable these surface treatments to yield high Q₀.

43 PARTICLE ACCELERATORS↗
NASA NTRS1977

Bandwidth compression of synthetic aperture radar imagery by quantization of raw radar data

A study is made of the effects of quantization of the radar returns transmitted from aircraft or spacecraft employing a synthetic aperture radar system. The study is based on the output images obtained after one-bit, two-bit, and eight-bit quantizations and comparing the results to ground truth. In this way the degradation resulting from data or bandwidth reduction is determined. Quantization is evaluated in terms of crater scene, number of looks, and transmission error rate. It is found that two-bit quantization of raw radar data from homogeneous scenes processed to 32 looks yields nearly all the details of the original. One-bit quantization of raw radar data from homogeneous scenes processed to 32 looks yields a good visual representation of the scene but some fine detail is lost and the absolute reflectivity level is not reliable. Image quality is observed to improve with more looks and video and intermediate frequency quantization are not distinguishable even for one-bit quantizations. Image quality is not influenced by bit error rates less than about 2 to the -7th power.

Lipes, R. G.↗
NASA NTRS1987

Trellis-Coded Modulation for Fading Channels

In proposed communication system, digital signals transmitted efficiently over fading channel by combination of trellis coding and multiple-phase-shift keying with addition of asymmetry to signal set. Coding and modulation schemes not designed separately as in previous systems but integrated to yield bandwidth-efficient modulation and forward-error-correction coding. Helps to satisfy need for reliable high-quality transmission of voice and data between land-mobile units via satellites, where limitations of power and bandwidth imposed simultaneously. Also applicable to ionospheric communications between fixed or mobile units.

Simon, Marvin K.↗
NASA NTRS1986

Near-toll quality digital speech transmission in the mobile satellite service

This paper discusses system considerations for near-toll quality digital speech transmission in a 5 kHz mobile satellite system channel. Tradeoffs are shown for power performance versus delay for a 4800 bps speech compression system in conjunction with a 16 state rate 2/3 trellis coded 8PSK modulation system. The suggested system has an additional 150 ms of delay beyond the propagation delay and requires an E(b)/N(0) of about 7 dB for a Ricean channel assumption with line-of-sight to diffuse component ratio of 10 assuming ideal synchronization. An additional loss of 2 to 3 dB is expected for synchronization in fading environment.

Townes, S. A.↗
NASA NTRS1989

Space shuttle propulsion estimation development verification

The application of extended Kalman filtering to estimating the Space Shuttle Propulsion performance, i.e., specific impulse, from flight data in a post-flight processing computer program is detailed. The flight data used include inertial platform acceleration, SRB head pressure, SSME chamber pressure and flow rates, and ground based radar tracking data. The key feature in this application is the model used for the SRB's, which is a nominal or reference quasi-static internal ballistics model normalized to the propellant burn depth. Dynamic states of mass overboard and propellant burn depth are included in the filter model to account for real-time deviations from the reference model used. Aerodynamic, plume, wind and main engine uncertainties are also included for an integrated system model. Assuming uncertainty within the propulsion system model and attempts to estimate its deviations represent a new application of parameter estimation for rocket powered vehicles. Illustrations from the results of applying this estimation approach to several missions show good quality propulsion estimates.

Rogers, Robert M.↗
NASA NTRS1994

Hydrogen maser clocks in space for solid-Earth research and time-transfer applications: Experiment overview and evaluation of Russian miniature sapphire loaded cavity

The Observatoire Cantonal de Neuchatel (ON) is developing for ESTEC a compact H-maser for space use based upon a miniature sapphire loaded microwave cavity, a technique pioneered at VNIIFTRI. Various contacts between West-European parties, headed by ESA, and the Russian parties, headed by ESA, led to the proposal for flying two H-masers on Meteor 3M, a Russian meteorology satellite in low polar orbit. The experiment will include two masers, one provided by ON and the other by VNIIFTRI. T/F transfer and precise positioning will be performed by both a microwave link, using PRARE equipment, and an optical link, using LASSO-like equipment. The main objectives of the experiment are precise orbit determination and point positioning for geodetic/geophysical research, ultra-accurate time comparison and dissemination as well as in-orbit demonstration of operation and performance of H-masers. Within the scope of a preliminary space H-maser development phase performed for ESTEC at ON in preparation to the joint experiment, a Russian miniature sapphire loaded microwave cavity, on loan from VNIIFTRI, was evaluated in a full-size EFOS hydrogen maser built by ON. The experimental evaluation confirmed the theoretical expectation that with a hydrogen storage volume of only 0.65 liter an atomic quality factor of 1.5 x 10(exp 9) can be obtained for a -105 dBm output power. This represents a theoretical Allan deviation of 1.7 x 10(exp -15) averaged on a 1000 s time interval. From a full-size design to a compact one, therefore, the sacrifice in performance due to the reduction of the storage volume is very small.

Busca, G.↗
NASA NTRS1993

Phase 3 integrated water recovery testing at MSFC: Single loop test results and lessons learned

A series of tests has been conducted at the NASA Marshall Space Flight Center (MSFC) to evaluate the performance of the Space Station Freedom (SSF) water recovery system. Potable and urine reclamation processors were integrated with waste water generation equipment and sucessfully operated for a total of 144 days. This testing marked the first occasion in which the waste feed sources for the previous potable and hygiene loops were combined into a single loop and processed to potable water quality. Reclaimed potable water from the combined waste waters routinely met the SSF water quality specifications.In the last stage of testing, data was obtained that indicated that the water processor (WP) presterilizer may not be required to meet the potable water quality specification. The removal of the presterilizer from the Water Processor design would provide a significant power savings, though an increase in the residence time of the catalytic oxidation reactor may be required to meet the potable microbial and total Organic Carbon specifications. This paper summarizes the test objectives, system design, test activities/protocols, significant results/anomalies and major lessons learned.

Carter, Donald Layne↗
NASA NTRS1994

Decision Making in Action: Applying Research to Practice

The importance of decision-making to safety in complex, dynamic environments like mission control centers and offshore installations has been well established. NASA-ARC has a program of research dedicated to fostering safe and effective decision-making in the manned spaceflight environment. Because access to spaceflight is limited, environments with similar characteristics, including aviation and nuclear power plants, serve as analogs from which space-relevant data can be gathered and theories developed. Analyses of aviation accidents cite crew judgement and decision making as causes or contributing factors in over half of all accidents. A similar observation has been made in nuclear power plants. Yet laboratory research on decision making has not proven especially helpful in improving the quality of decisions in these kinds of environments. One reason is that the traditional, analytic decision models are inappropriate to multidimensional, high-risk environments, and do not accurately describe what expert human decision makers do when they make decisions that have consequences. A new model of dynamic, naturalistic decision making is offered that may prove useful for improving decision making in complex, isolated, confined and high-risk environments. Based on analyses of crew performance in full-mission simulators and accident reports, features that define effective decision strategies in abnormal or emergency situations have been identified. These include accurate situation assessment (including time and risk assessment), appreciation of the complexity of the problem, sensitivity to constraints on the decision, timeliness of the response, and use of adequate information. More effective crews also manage their workload to provide themselves with time and resources to make good decisions. In brief, good decisions are appropriate to the demands of the situation. Effective crew decision making and overall performance are mediated by crew communication. Communication contributes to performance because it assures that all crew members have essential information, but it also regulates and coordinates crew actions and is the medium of collective thinking in response to a problem. This presentation will examine the relations between leadership, communication, decision making and overall crew performance. Implications of these findings for spaceflight and training for offshore installations will be discussed.

Orasanu, Judith↗
NASA NTRS1994

Decision Making in Action

The importance of decision-making to safety in complex, dynamic environments like mission control centers and offshore installations has been well established. NASA-ARC has a program of research dedicated to fostering safe and effective decision-making in the manned spaceflight environment. Because access to spaceflight is limited, environments with similar characteristics, including aviation and nuclear power plants, serve as analogs from which space-relevant data can be gathered and theories developed. Analyses of aviation accidents cite crew judgement and decision making as causes or contributing factors in over half of all accidents. A similar observation has been made in nuclear power plants. Yet laboratory research on decision making has not proven especially helpful in improving the quality of decisions in these kinds of environments. One reason is that the traditional, analytic decision models are inappropriate to multidimensional, high-risk environments, and do not accurately describe what expert human decision makers do when they make decisions that have consequences. A new model of dynamic, naturalistic decision making is offered that may prove useful for improving decision making in complex, isolated, confined and high-risk environments. Based on analyses of crew performance in full-mission simulators and accident reports, features that define effective decision strategies in abnormal or emergency situations have been identified. These include accurate situation assessment (including time and risk assessment), appreciation of the complexity of the problem, sensitivity to constraints on the decision, timeliness of the response, and use of adequate information. More effective crews also manage their workload to provide themselves with time and resources to make good decisions. In brief, good decisions are appropriate to the demands of the situation. Effective crew decision making and overall performance are mediated by crew communication. Communication contributes to performance because it assures that all crew members have essential information, but it also regulates and coordinates crew actions and is the medium of collective thinking in response to a problem. This presentation will examine the relations between leadership, communication, decision making and overall crew performance. Implications of these findings for spaceflight and training for offshore installations will be discussed.

Orasanu, Judith↗
NASA NTRS1983

Mineral/Water Analyzer

An x-ray fluorescence spectrometer developed for the Viking Landers by Martin Marietta was modified for geological exploration, water quality monitoring, and aircraft engine maintenance. The aerospace system was highly miniaturized and used very little power. It irradiates the sample causing it to emit x-rays at various energies, then measures the energy levels for sample composition analysis. It was used in oceanographic applications and modified to identify element concentrations in ore samples, on site. The instrument can also analyze the chemical content of water, and detect the sudden development of excessive engine wear.

Source record↗
NASA NTRS2003

[Measurements of "Total Water" and Carbon Dioxide from the NASA WB-57 During Crystal-Face]

An existing closed-path tunable diode laser hygrometer (CLH) was employed for the measurements of total water made during CRYSTAL-FACE. This instrument had flown previously on the NASA DC-8 during the SAGE III Ozone Loss and Validation Experiment (SOLVE) and also on the NCAR C-130 during some local flights designed to test the extent of water vapor interference in carbon dioxide measurements. The instrument was largely unchanged from previous studies, but a new inlet appropriate to the WB-57F wingpod was constructed. In order to minimize the impact on the over-subscribed right wingpod and to achieve good thermal control of the inlet temperature, the CLH inlet was made of carbon-fiber/epoxy composite. Considerable effort was spent to design and build the lightest possible mounting hardware and design relatively low-power inlet heaters. As a result, the instrument and mounting hardware came in below the NASA/JSC-imposed weight cap of 35 lbs. Data were obtained on all test flights during May 2002 and during all but one mission flight in July 2002 (the one lost flight was due to an unplugged instrument power cable). Instrument performance during the test flights was good, but the data are not science- quality, as a variety of tests were performed to optimize the inlet configuration and heating. Data on all mission flights is of high quality, despite some difficulties caused by flying through wet low-altitude air masses and dense anvils, which saturated the instrument response.

Avallone, Linnea M.↗
NASA NTRS2004

Integration of On-board EOS Schedule Revision with Space Communication Emulation System

The need for on-board decision-making for planning science observations on Earth Observing Satellites is based on the fact that the desirability of acquiring an image can change dynamically, because of changes in meteorological conditions (e.g. cloud cover), unforeseen events such as fires, floods, or volcanic eruptions, or unexpected changes in satellite or ground station capability. In such cases, satellite resources, such as power and SSR capacity can potentially be better utilized taking another image that is of higher quality. Currently, typical Earth observing satellites cannot communicate directly with each other, and can only communicate with ground stations about 5% to 10% of the time. Because of the limited communication windows, as well as the cost and effort that would need to be expended in revising a mission schedule, a ground-based scheduler would have little or no opportunity to revise the schedule in response to the contingencies that may arise. For this reason, a distributed science planning system combining a ground-based scheduler with on-board schedule revision capabilities is warranted. This paper will describe algorithms for on-board decision-making for science planning and their integration with the advanced satellite control and communications technology developed at the Space Communication Emulation Facility (SCEF) at NASA Glenn Research Center. Our objective of demonstrating how advanced communications and scheduling technology can be combined to improve the scientific utility of images acquired by Earth observing systems will be discussed via a description of a number of realistic flight scenarios.

Khatib, Lina↗