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Results for “Lithium ion”

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 559 records · Page 31
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

A study of beryllium and beryllium-lithium complexes in single crystal silicon

When beryllium is thermally diffused into silicon, it gives rise to acceptor levels 191 MeV and 145 meV above the valence band. Quenching and annealing studies indicate that the 145-MeV level is due to a more complex beryllium configuration than the 191-MeV level. When lithium is thermally diffused into a beryllium-doped silicon sample, it produces two acceptor levels at 106 MeV and 81 MeV. Quenching and annealing studies indicate that these levels are due to lithium forming a complex with the defects responsible for the 191-MeV and 145-MeV beryllium levels, respectively. Electrical measurements imply that the lithium impurity ions are physically close to the beryllium impurity atoms. The ground state of the 106-MeV beryllium level is split into two levels, presumably by internal strains. Tentative models are proposed.

Crouch, R. K.↗
NASA NTRS1984

Predictions of lithium interactions with earth's bow shock in the presence of wave activity

The results of a test-particle simulation studying the movement of a lithium tracer ion injected upstream of the bow shock are reported. Wave activity consists of parallel and antiparallel propagating Alfven waves characterized by a frequency power spectrum within a frequency or range of amplitudes defined separately in the upstream and downstream regions. The results show that even a moderate level of wave activity can substantially change the results obtained in the absence of waves. Among the effects observed are: (1) increased ion transmission; (2) both the average energy gain and spread about the average are increased for transmitted and reflected particles; (3) the average final pitch angle for transmitted particles tends to 90 deg, and the spread of reflected particles is reduced; and (4) the spatial dispersion of the ions on the bow shock after a single encounter is increased.

Decker, R. B.↗
NASA NTRS2024

NASA Engineering and Safety Center Technical Bulletins 2007-2023

An NESC Technical Bulletin captures critical knowledge in the form of new engineering information or best practices in a one-page format that have resulted from NESC independent testing, analysis, and assessments. This document contains all NESC Technical Bulletins from 2007 through 2023.

additive manufacturing, battery, braycote, capacit↗
NASA NTRS2023

Identifying and Documenting Expert Knowledge, A Practical Study of Design Patterns

Globalization, powered by digitization, is increasing technology growth and knowledge transfer rates to levels not seen in the previous 3500 years, obscuring absolute truth and accelerating rates of innovation and production. Competing,or remaining competitive, in this global marketplace requires a learning organization adopt a method of capture, retention, and reuse for demonstrated tacit knowledge to accelerate the development of increasingly complex systems of high quality at a reasonable cost. The architectural theory of Patterns and Pattern Language is a validated methodology for mining tacit domain knowledge from a proven system. This work applies architectural theory to a multi-year development experiment and captures exposed knowledgeas a design patternin a model based systems engineering tool, demonstrating applicability ofdigital engineering initiativesin thedescription and reuse of expert design knowledge.By creating and archiving model based expressions of expert knowledge,a learning organization canimprovepractical decision making and avoid uninformed concept phase decision making

systems engineering↗
NASA NTRSDate not supplied

The Emphasis of Design Patterns in Expressing Expert Knowledge From A Technical Solution – A Framework for Continued Research

Digital Engineering is a transformative strategy that leverages an integrated model-based approach to improve communication, decision making, design understanding, and acquisition efficiency of system development. As modern systems are derived from pre-existing systems, harvesting expert knowledge from proven systems in a useful, model-based way will reduce the experiential learning and cognition required for new system development, contributing to a Digital Engineering transformation. Motivated by performance gains observed during a multi-year, sequential development activity, this survey reviews knowledge, architecture, and pattern literature to establish a framework for research of architectural methods for expert knowledge identification and description using Model Based System Engineering. The multi-year sequential development activity is offered as the experimental system of interest for this research. This work aims to enable a digital engineering strategy that improves concept phase decision making, accelerates knowledge acquisition from lessons learned repositories, and eases the burden of generational knowledge loss.

Lithium Ion↗
NASA NTRSDate not supplied

Power Hibernation for Low-Cost Solar Powered Lunar Missions

Lunar Surface temperatures can span from equatorial highs near 400K and polar lows of 50K. The extreme cold combined with the 354-hour duration of the lunar night is particularly challenging for small robotic lander missions. NASA’s Commercial Lunar Payload Services (CLPS) missions involve robotic landers intended to provide low-cost access to the lunar surface. Current CLPS Missions are solar powered and are only intended to survive a single lunar day. The ability to survive the night and continue operations over many lunar cycles would provide a dramatic increase in science productivity. The Power Hibernation approach relies on battery cells that can tolerate the extreme cold night and recover once temperatures return to normal. System recovery from hibernation depends on power electronics that can “cold start” at lunar dawn and operate on solar array output alone. Once battery and avionics systems are restored the spacecraft resumes daytime operations. The challenge is to achieve this capability with minimum impact to the spacecraft design and payload capacity. This talk will describe recent and ongoing investigations in battery and electronics technologies that will enable power hibernation and recovery.

Space Power↗
NASA NTRSDate not supplied

Power Hibernation for Low-Cost Solar Powered Lunar Missions

Lunar Surface temperatures can span from equatorial highs near 400K and polar lows of 50K. The extreme cold combined with the 354-hour duration of the lunar night is particularly challenging for small robotic lander missions. NASA’s Commercial Lunar Payload Services (CLPS) missions involve robotic landers intended to provide low-cost access to the lunar surface. Current CLPS Missions are solar powered and are only intended to survive a single lunar day. The ability to survive the night and continue operations over many lunar cycles would provide a dramatic increase in science productivity. The Power Hibernation approach relies on battery cells that can tolerate the extreme cold night and recover once temperatures return to normal. System recovery from hibernation depends on power electronics that can “cold start” at lunar dawn and operate on solar array output alone. Once battery and avionics systems are restored the spacecraft resumes daytime operations. The challenge is to achieve this capability with minimum impact to the spacecraft design and payload capacity. This talk will describe recent and ongoing investigations in battery and electronics technologies that will enable power hibernation and recovery.

Space Power↗
NASA NTRS2018

Optimized Wavelength-Tuned Nonlinear Frequency Conversion Using a Liquid Crystal Clad Waveguide

An optimized wavelength-tuned nonlinear frequency conversion process using a liquid crystal clad waveguide. The process includes implanting ions on a top surface of a lithium niobate crystal to form an ion implanted lithium niobate layer. The process also includes utilizing a tunable refractive index of a liquid crystal to rapidly change an effective index of the lithium niobate crystal.

Stephen, Mark A.↗
NASA NTRS1994

A future, intense source of negative hydrogen ions

By directly heating lithium hydride in a vacuum, up to 18 micro-A/sq cm of negative hydrogen has been obtained from the crystal lattice. The amount of ion current extracted and analyzed is closely related to the temperature of the sample and to the rate at which the temperature is changed. The ion current appears to be emission limited and saturates with extraction voltage. For a fixed extraction voltage, the ion current could be maximized by placing a grid between the sample surface and the extraction electrode. Electrons accompanying the negative ions were removed by a magnetic trap. A Wein velocity filter was designed and built to provide definitive mass analysis of the extracted ion species. This technique when applied to other alkali hydrides may produce even higher intensity beams possessing low values of emittance.

Siefken, Hugh↗