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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 1,387 records · Page 77
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Fundamentals of Three-Terminal Tandem Solar Cells: a Comprehensive Taxonomy

Three-terminal tandem (3TT) solar cells can overcome some of the limitations of two- and four-terminal tandem designs. However, the coupled nature of the cells adds a degree of complexity to the devices themselves and the ways that their performance can be measured and reported. To facilitate understanding, we have developed a taxonomy which encompasses all types of 3TT devices, enabling a common nomenclature for discussing devices and performance. Once the physical devices, contact nodes, and loading circuitry have been self-consistently described, it becomes apparent that a wide range of 3TT devices share a common set of design and operating principles.

3T↗
DOE OSTI2016

Fabrication of wound capacitors using flexible alkali-free glass

Here, alkali-free glasses, which exhibit high energy storage densities (~35 J/cc), present a unique opportunity to couple high temperature stability with high breakdown strength, and thus provide an avenue for capacitor applications with stringent temperature and power requirements. Realizing the potential of these materials in kilovolt class capacitors with >1 J/cc recoverable energy density requires novel packaging strategies that incorporate these extremely fragile dielectrics. In this paper, we demonstrate the feasibility of fabricating wound capacitors using 50-μm-thick glass. Two capacitors were fabricated from 2.8-m-long ribbons of thin (50 μm) glass wound into 125-140-mm-diameter spools. The capacitors exhibit a capacitance of 70-75 nF with loss tangents below 1%. The wound capacitors can operate up to 1 kV and show excellent temperature stability to 150 °C. By improving the end terminations, the self-resonance can be shifted to above 1 MHz, indicating that these materials may be useful for pulsed power applications with microsecond discharge times.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2012

Optimizing charge neutralization for a magnetic sector SIMS instrument in negative mode

Successful self-adjusted charge compensation was demonstrated for a CAMECA magnetic-sector secondary ion mass spectrometer applied in negative mode. Operation with the normal-incidence electron gun (NEG) potential positively biased relative to a sample potential enables substantial broadening of the Cs primary-ion-current density range available for analysis of insulators. The decrease of the negative NEG potential by 30 V allows the highest value of primary current density used for the analysis of a silica sample to increase by a factor of more than 6. By applying the improved charge neutralization technique, accurate Na depth profiles for SiO{sub 2} samples were obtained within detection limits of {approx}3 Multiplication-Sign 10{sup 15} atoms/cm{sup 3}.

42 ENGINEERING↗
DOE OSTI2013

Southeast Regional CO 2 Sequestration Technology Training Program (SECARB-Ed)

Carbon capture and storage (CCS) technologies have tremendous potential for reducing carbon dioxide (CO 2 ) emissions and mitigating global climate change. These technologies encourage economic growth and have manageable influence on energy use. Deploying these technologies on a commercial scale will require expanding the workforce, including geologists, engineers, scientists and technicians, trained in CCS specialties. In 2009, the U.S. Department of Energy’s (DOE) National Energy Technology Laboratory (NETL) selected seven projects to help develop regional sequestration technology training centers in the United States. The “Southeast Regional CO 2 Sequestration Technology Training Program” (SECARB-Ed) was managed and administered by the Southern States Energy Board (SSEB) from November 16, 2009, to November 15, 2012. During this performance period, the SECARB-Ed partners were successful in achieving their primary objective of developing a self-sustaining regional CO 2 sequestration training program to facilitate the transfer of knowledge and technologies required for site development, operations and monitoring of commercial CCS projects. An experienced team of professionals participated in the SECARB-Ed program, with skills and competencies in geosciences, reservoir engineering and CCS related capture/separation, transportation, legal and regulatory disciplines. The SECARB-Ed Advisory Board included representatives from SSEB, Clemson University, GERALD R HILL PHD, Inc. (HILL), EnTech Strategies, LLC- Research Experience in Carbon Sequestration (RECS), Virginia Tech (VAT), Geological Survey of Alabama (GSA) at The University of Alabama and the Bureau of Economic Geology (BEG) at The University of Texas at Austin. The program encompasses fifteen of SSEB’s member states, including: Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Mississippi, Missouri, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, Virginia and West Virginia. The SECARB-Ed partners implemented an organized sponsorship development program, developed short courses on CCS technologies, participated in regional training and other activities through outreach and networking and performed internet-based and electronic regional/basin technology transfer services. The partners addressed the most promising sequestration options in the region; the mix of industry and power plant sources of CO 2 ; regional transportation infrastructure; and the legal, regulatory, and institutional frameworks that exist in the southeast. As a result, SECARB-Ed fostered the development of a future workforce with disciplines specific to applied engineering and CCS science and technologies and advance the United States in its position as the leader in addressing climate change, near-zero emissions technologies and geologic sequestration technologies. The educational and training opportunities detailed in this Final Report demonstrate an effective means of disseminating a broad base of such knowledge and skills to a variety of students and professionals who are interested in the area of CCS technologies. The efforts of the SECARB-Ed Advisory Board and partners have resulted in a total of 1,951 professional development hours (PDHs) awarded to 1,131 participants.

Baskin, Kathryn A.↗
DOE OSTI2015

Research Challenges in Magneto-Inertial Fusion

Inertial Confinement Fusion (ICF) is a grand challenge for high-energy-density science. In traditional ICF, alpha heating is achieved by producing T ~ 4 keV hot spot surrounded by a high areal density (ρR ~1 g/cm 2 ) of cold fuel, requiring hot-spot pressures above 400 Gbar. In Magneto-Inertial Fusion (MIF), the pressure and areal density requirements are relaxed by the presence of a magnetic field strong enough to magnetically confine charged particles within a radius smaller than the fuel radius. The key parameter for MIF is thus BR rather than ρR, and for BR >0.5 MG-cm, the magnetic field effectively traps electrons, 1 MeV tritons, and fusion-produced alpha particles for almost arbitrarily small ρR. Consequently, thermal conduction losses are reduced and trapped alpha particles return much of their energy to the burning plasma. Operating at intermediate plasma density and pressure regimes between traditional magnetic confinement fusion and ICF systems, MIF concepts achieve self-heating at pressures of only ~5 Gbar, with GJ-scale yields appearing possible. Ongoing experiments demonstrate good inertial and magnetic confinement, stable implosions, and promising yields, but challenges remain in optimizing preheat, mitigating mix, and understanding fundamental plasma physics and magneto-hydrodynamic behavior in these extreme conditions.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1975

Fabrication and testing of negative limited sealed nickel-cadmium cells

A number of 20 Ah and 3 Ah negative limited nickel-cadmium cells were fabricated and assembled in hermetically sealed stainless steel containers. The cells exhibit a large voltage rise signal, in excess of 250 mA, at the end of each charge period. They also exhibit lower self discharge rates than conventional sealed nickel-cadmium cells and do not require overcharge. The cells are capable of operating at charge and discharge rates up to 5C and can deliver at least 1000 cycles on a 30 minute regime at 25% DOD. A small amount of gassing occurs, but is not deemed critical or detrimental in view of the facts that, (1) operating pressures are in the range of 7 to 20 psig and (2) the cells are operated in the flooded condition so therefore contain little internal void volume. The cells were found to exhibit somewhat higher capacity loss rates during cycling than conventional sealed nickel-cadmium batteries.

Gordy, D. J.↗
NASA NTRS1980

Space shuttle main engine digital controller

The controller provides responsive control of engine thrust and mixture ratio through the digital computer in the controller, updating the instructions to the engine control elements 50 times per second (every 20 milliseconds). Additionally, precise engine performance is achieved through closed loop control, utilizing 16 bit computation, 10 bit input/output resolution, and self calibrating analog-to-digital conversion. Engine reliability is enhanced by a dual redundant control system that allows normal operation after the first failure and a fail-safe shutdown after a second failure. The digital computer is programmable, allowing modification of engine control equations and constants by change of the stored program (software). The controller is packaged in a sealed, pressurized chassis with cooling provided by convection heat transfer through pin fins as part of the main chassis. The electronics are distributed on functional modules having special provisions for thermal and vibrational protection.

Mitchell, W. T.↗
NASA NTRS1983

Computer science: Key to a space program renaissance. The 1981 NASA/ASEE summer study on the use of computer science and technology in NASA. Volume 2: Appendices

Adoption of an aggressive computer science research and technology program within NASA will: (1) enable new mission capabilities such as autonomous spacecraft, reliability and self-repair, and low-bandwidth intelligent Earth sensing; (2) lower manpower requirements, especially in the areas of Space Shuttle operations, by making fuller use of control center automation, technical support, and internal utilization of state-of-the-art computer techniques; (3) reduce project costs via improved software verification, software engineering, enhanced scientist/engineer productivity, and increased managerial effectiveness; and (4) significantly improve internal operations within NASA with electronic mail, managerial computer aids, an automated bureaucracy and uniform program operating plans.

Freitas, R. A., Jr.↗
NASA NTRS1982

Pilot selection and training

Personality and situational factors relevant to individual and group performance in highly demanding environments, such as those faced by astronauts or by jet transport crew, are discussed. It is emphasized that although technical competence and proficiency in pilot selection are prerequisites for safety, operating a modern jet transport is a group endeavor that requires the effective coordination of the entire crew. A self-report test battery for measuring positive and negative personality traits of pilot candidates, termed the Personal Characteristics Inventory, is described.

Helmreich, Robert L.↗
NASA NTRS1990

Dissociation phenomena in electron-beam sustained carbon dioxide lasers

A number of applications are emerging requiring efficient, long pulse, long-life sealed CO2 lasers. Examples include the proposed NASA and ESA wind lidars. Electron-beam sustained discharge devices are strong contenders. Unlike self-sustained discharges, e-beam sustenance readily provides efficient performance from large volume discharges and offers pulse lengths well in excess of the microsecond or so generally associated with self-sustained devices. In the case of the e-beam sustained laser, since the plasma is externally maintained and operated at electric field strengths less than that associated with the glow to arc transition, the discharges can be run even in the presence of strongly attacking species such as O2. Build up of large levels of attacking contaminants is nevertheless undesirable as their presence reduces the current drawn by the plasma and thus the pumping rate to the upper laser level. The impedance rise leads to a mismatch of the pulse forming network with a consequent loss of control over energy deposition, operating E/N, and gain. Clearly CO2 dissociation rates, the influence of dissociation products on the discharge and gain, and tolerance of the discharge to these products need to be determined. This information can then be used to assess co-oxidation catalyst requirements for sealed operation.

Harris, Michael R.↗
NASA NTRS1993

A high power lithium thionyl chloride battery for space applications

A high power, 28 V, 330 A h, active lithium thionyl chloride battery has been developed for use as main and payload power sources on an expendable launch vehicle. Nine prismatic cells, along with the required electrical components and a built-in heater system, are efficiently packaged resulting in significant weight savings over presently used silver-zinc batteries. The high rate capability is achieved by designing the cells with a large electrochemical surface area and impregnating an electrocatalyst, polymeric phthalocyanine, into the carbon cathodes. Passivation effects are reduced with the addition of sulfur dioxide into the thionyl chloride electrolyte solution. The results of conducting a detailed thermal analysis are utilized to establish the heater design parameters and the thermal insulation requirements of the battery. An analysis of cell internal pressure and vent characteristics clearly illustrates the margins of safety under different operating conditions. Performance of fresh cells is discussed using polarization scan and discharge data at different rates and temperatures. Self-discharge rate is estimated based upon test results on cells after storage. Results of testing a complete prototype battery are described.

Shah, Pinakin M.↗
NASA NTRS1999

Carbon Fiber Reinforced Carbon Composites Rotary Valves for Internal Combustion Engines

Carbon fiber reinforced carbon composite rotary, sleeve, and disc valves for internal combustion engines and the like are disclosed. The valves are formed from knitted or braided or warp-locked carbon fiber shapes. Also disclosed are valves fabricated from woven carbon fibers and from molded carbon matrix material. The valves of the present invention with their very low coefficient of thermal expansion and excellent thermal and self-lubrication properties, do not present the sealing and lubrication problems that have prevented rotary, sleeve, and disc valves from operating efficiently and reliably in the past. Also disclosed are a sealing tang to further improve sealing capabilities and anti-oxidation treatments.

Northam, G. Burton↗
NASA NTRS2000

Carbon Fiber Reinforced Carbon Composite Rotary Valve for an Internal Combustion Engine

Carbon fiber reinforced carbon composite rotary sleeve, and disc valves for internal combustion engines and the like are disclosed. The valves are formed from knitted or braided or wrap-locked carbon fiber shapes. Also disclosed are valves fabricated from woven carbon fibers and from molded carbon matrix material. The valves of the present invention with their very low coefficient of thermal expansion and excellent thermal and self-lubrication properties do not present the sealing and lubrication problems that have prevented rotary sleeve and disc valves from operating efficiently and reliably in the past. Also disclosed are a sealing tang to further improve sealing capabilities and anti-oxidation treatments.

Northam, G.Burton↗
DOE OSTI2020

Acute shortage ventilator

We have implemented an ″Acute Shortage Ventilator″ (ASV) motivated by the COVID-19 pandemic and the possibility of severe ventilator shortages in the near future. The unit cost per ventilator is less than $400 US excluding the patient circuit parts. The ASV mechanically compresses a self-inflating bag resuscitator, uses a modified patient circuit, and is commanded by a microcontroller and an optional laptop. It operates in both Volume-Controlled Assist-Control mode and a Pressure-Controlled Assist-Control mode. It has been tested using an artificial lung against the EURS guidelines. The key design goals were to develop a simple device with high performance for short-term use, made primarily from common hospital parts and generally-available non-medical components, and at low cost and ease in manufacturing.

Breur, Sander↗
DOE OSTI2011

A general solution-chemistry route to the synthesis LiMPO{sub 4} (M=Mn, Fe, and Co) nanocrystals with [010] orientation for lithium ion batteries

A general and efficient solvothermal strategy has been developed for the preparation of lithium transition metal phosphate microstructures (LiMnPO{sub 4}, LiFePO{sub 4}, and LiCoPO{sub 4}), employing ethanol as the solvent, LiI as the Li source, metal salts as the M sources, H{sub 3}PO{sub 4} as the phosphorus source, and poly(vinyl pyrrolidone) (PVP) as the carbon source and template. This route features low cost, environmental benign, and one-step process for the cathode material production of Li-ion batteries without any complicated experimental setups and sophisticated operations. The as-synthesized LiMPO{sub 4} microstructures exhibit unique, well-shaped and favorable structures, which are self-assembled from microplates or microrods. The b axis is the preferred crystal growth orientation of the products, resulting in a shorter lithium ion diffusion path. The LiFePO{sub 4} microstructures show an excellent cycling stability without capacity fading up to 50 cycles when they are used as a cathode material in lithium-ion batteries. - Graphical abstract: A general and efficient solvothermal strategy has been developed for the preparation of lithium transition metal phosphate microstructures under solvothermal conditions in the presence of PVP. Highlights: > A general and efficient solvothermal strategy has been developed for the preparation of LiMPO{sub 4} microstructures. > This route features low cost, environmental benign, and one-step process. > The LiMPO{sub 4} microstructures exhibit unique, well-shaped, and favorable structures. > The LiFePO{sub 4} microstructures show an excellent cycling stability up to 50 cycles as a cathode material of lithium-ion batteries.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Steering the methanol steam reforming reactivity of intermetallic Cu–In compounds by redox activation: stability vs . formation of an intermetallic compound–oxide interface

To compare the inherent methanol steam reforming properties of intermetallic compounds and a corresponding intermetallic compound–oxide interface, we selected the Cu–In system as a model to correlate the stability limits, self-activation and redox activation properties with the catalytic performance. Three distinct intermetallic Cu–In compounds – Cu 7 In 3 , Cu 2 In and Cu 11 In 9 – were studied both in an untreated and redox-activated state resulting from alternating oxidation–reduction cycles. The stability of all studied intermetallic compounds during methanol steam reforming (MSR) operation is essentially independent of the initial stoichiometry and all accordingly resist substantial structural changes. The inherent activity under batch MSR conditions is highest for Cu 2 In, corroborating the results of a Cu 2 In/In 2 O 3 sample accessed through reactive metal–support interaction. Under flow MSR operation, Cu 7 In 3 displays considerable deactivation, while Cu 2 In and Cu 11 In 9 feature stable performance at simultaneously high CO 2 selectivity. Here, the missing significant self-activation is most evident in the operando thermogravimetric experiments, where no oxidation is detected for any of the intermetallic compounds. In situ X-ray diffraction allowed us to monitor the partial decomposition and redox activation of the Cu–In intermetallic compounds into Cu 0.9 In 0.1 /In 2 O 3 (from Cu 7 In 3 ), Cu 7 In 3 /In 2 O 3 (from Cu 2 In) and Cu 7 In 3 /Cu 0.9 In 0.1 /In 2 O 3 (from Cu 11 In 9 ) interfaces with superior MSR performance compared to the untreated samples. Although the catalytic profiles appear surprisingly similar, the latter interface with the highest indium content exhibits the least deactivation, which we explain by formation of stabilizing In 2 O 3 patches under MSR conditions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1976

Optimum load device for DMOS integrated circuits

Depletion-mode load devices can be integrated with DMOS transistors without any extra diffusions or ion implantation processing steps by judicious choice of the substrate crystal orientation and resistivity. For low voltage operation line-type 1, 1, 1 crystal orientation should be used. The line-type 1, 1, 1 crystal orientation also yields a higher transconductance for the DMOS transistor than the line-type 1, 0, 0 orientation. The geometry of the load device and the DMOS transistor can be made ratioless to conserve area. Self-aligned gates, hitherto considered incompatible with DMOS transistors, have been incorporated in the structure. The experimental DMOS inverters, using a conservative design, have achieved 4-ns propagation delay, 1.3-V operation, and 2-pJ propagation delay-power dissipation product.

Lin, H. C.↗
DOE OSTI2012

Aspect ratio effects on neoclassical tearing modes from comparison between DIII-D and National Spherical Torus Experiment

Neoclassical tearing mode islands are sustained by helically perturbed bootstrap currents arising at finite beta from toroidal effects that trap a fraction of the particles in non-circulating orbits. DIII-D and NSTX are here operated with similar shape and cross-sectional area but almost a factor of two difference in inverse aspect ratio a/R. In these experiments, destabilized n=1 tearing modes were self-stabilized (reached the 'marginal point') by reducing neutral-beam power and thus beta. The measure of the marginal island gives information on the small-island stabilizing physics that in part (with seeding) governs onset. The marginal island width on NSTX is found to be about three times the ion banana width and agrees with that measured in DIII-D, except for DIII-D modes closer to the magnetic axis, which are about two times the ion banana width. There is a balance of the helically perturbed bootstrap term with small island effects with the sum of the classical and curvature terms in the modified Rutherford equation for tearing-mode stability at the experimental marginal point. Empirical evaluation of this sum indicates that while the stabilizing effect of the curvature term is negligible in DIII-D, it is important in NSTX. The mode temporal behavior from the start of neutral-beam injection reduction also suggests that NSTX operates closer to marginal classical tearing stability; this explains why there is little hysteresis in beta between mode onset, saturation, and self-stabilization (while DIII-D has large hysteresis in beta). NIMROD code module component calculations based on DIII-D and NSTX reconstructed experimental equilibria are used to diagnose and confirm the relative importance of the stabilizing curvature effect, an advantage for low aspect ratio; the relatively greater curvature effect makes for less susceptibility to NTM onset even if the classical tearing stability index is near marginal.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗