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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 973 records · Page 54
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

All-YBa2Cu3O(7-x) edge-geometry weak links

High quality YBa2Cu3O(7-x)/normal-metal/YBa2Cu3O(7-x) edge-geometry weak links are fabricated using nonsuperconducting Y-Ba-Cu-O barrier layers deposited by laser ablation at reduced growth temperatures. Devices incorporating 25-100-A-thick barrier layers exhibit current-voltage characteristics consistent with the resistively-shunted-junction model, as well as ac Josephson steps. Magnetic field modulation of the critical currents shows Fraunhofer-like behavior with a periodicity which scales with device area. The critical currents vary exponentially with barrier thickness indicating an effective normal metal coherence length of 20 A. The average resistances scale linearly with Y-Ba-Cu-O interlayer thickness and device area. The scaling behavior of the device parameters combined with the well-behaved magnetic field modulation of the critical currents demonstrates good barrier-layer uniformity with low pinhole densities. Near the transition temperature, the critical currents exhibit a temperature dependence proportional to (1 - T/Tc) squared.

Hunt, B. D.↗
NASA NTRS1991

The necessity of on board oxygen for airbreathing single-stage-to-orbit vehicles

Vehicle performance and sizing impacts of stored oxygen are examined for SSTO vehicles such as the National Aerospace Plane. The relationship between propulsion efficiency and thrust-to-drag ratio is presented. Idealistic and substantive values for these parameters are compared. The impact of these two parameters as well as propellant density on vehicle sizing is investigated. Representative configurations are provided for comparison purposes.

Martin, John G.↗
NASA NTRS1992

A dynamic isotope power system for Space Exploration Initiative surface transport systems

The Dynamic Isotope Power System (DIPS) Demonstration Program, sponsored by the U.S. Department of Energy with support funding from NASA, is currently focused on the development of a standardized 2.5-kWe portable generator for multiple applications on the lunar or Martian surface. A variety of remote and mobile potential applications have been identified by NASA, including surface rovers for both short- and extended-duration missions, remote power to science packages, and backup to central base power. Recent work focused on refining the 2.5-kWe design and emphasizing the compatibility of the system with potential surface transport systems. Work included an evaluation of the design to ensure compatibility with the Martian atmosphere while imposing only a minor mass penalty on lunar operations. Additional work included a study performed to compare the DIPS with regenerative fuel cell systems for lunar mobile and remote power systems. Power requirements were reviewed and a modular system chosen for the comparison.

Hunt, Maribeth E.↗
NASA NTRS1992

Modeling of planar quasi-TEM superconducting transmission lines

An application of the phenomenological loss equivalence method (Lee and Itoh, 1989) in modeling the microwave behavior of planar quasi-TEM superconducting transmission lines is presented. For validation of the model, data are used from measurements of a YBCO superconducting thin-film coplanar-waveguide lowpass filter on a lanthanum aluminate substrate. Measured and modeled S-parameters of an existing superconducting coplanar waveguide lowpass filter agree to within 0.3 dB in magnitude and 0.5 radians in phase. Extracted values for penetration depth and real part of the conductivity of the superconducting film are within 10 percent of other researchers' findings.

Antsos, Dimitrios↗
NASA NTRS1991

A dynamic isotope power system portable generator for the moon or Mars

The dynamic isotope power systems (DIPS) demonstration program is focused on a standardized 2.5 kWe portable generator for multiple uses on the lunar or Martian surface. A variety of potential remote or mobile applications has been identified by NASA. These applications include remote power to science packages, surface rovers for both short and extended duration missions, and backup to central base power. Reviews conducted on alternative power sources for these applications are described. These include the comparison of DIPS to regenerative fuel cells (RFCs). Recent work is presented refining the 2.5 kWe design to assure compatibility with the Martian environment while imposing only a minor mass penalty on lunar operations. This was accomplished by limiting temperatures, except in the heat source unit (HSU), to the nonrefractory materials regime and protecting the necessary refractories in the HSU from the environment. Design changes to the HSU are described. Work related to recent concerns regarding astronaut radiation doses is described. This work includes the bases for the calculations to determine the necessary shielding or operational limitations.

Johnson, Richard A.↗
NASA NTRS1993

Sandwich-Geometry YBa(2)Cu(3)O(7-delta)/Au/Nb SNS Devices

Superconductor/normal-conductor/superconductor (SNS) devices in which electronically active layers consist of high-temperature superconductor YBa(2)Cu(3)O(7-delta), normal conductor Au, and conventional superconductor Nb, fabricated in sandwich geometry. Devices and processes by which fabricated are part of continuing effort to develop SNS microbridges for use in superconducting quantum interference devices (SQUIDS's) or as mixers or local oscillators operating at frequencies of hundreds of gigahertz. Results show promise for manufacture of practical devices.

Foote, Marc C.↗
NASA NTRS1993

Edge-Geometry SNS Devices Made Of Y/Ba/Cu/O

Superconductor/normal-conductor/superconductor (SNS) devices in which electronically active layers consist solely of materials in Y/Ba/Cu/O system fabricated in edge geometry. Made of different materials described in "SNS Device Made With Edge-Defined Geometry" (NPO-18303). Advantages include desirable electrical characteristics and less difficulty in fabrication. Attractive for development into high-frequency oscillators, magnetic-field sensors, and submillimeter-wave mixers.

Hunt, Brian D.↗
NASA NTRS1990

First International Microgravity Laboratory

This colorful booklet presents capsule information on every aspect of the International Microgravity Laboratory (IML). As part of Spacelab, IML is divided into Life Science Experiments and Materials Science Experiments. Because the life and materials sciences use different Spacelab resources, they are logically paired on the IML missions. Life science investigations generally require significant crew involvement, and crew members often participate as test subjects or operators. Materials missions capitalize on these complementary experiments. International cooperation consists in participation by the European Space Agency, Canada, France, Germany, and Japan who are all partners in developing hardware and experiments of IML missions. IML experiments are crucial to future space ventures, like the development of Space Station Freedom, the establishment of lunar colonies, and the exploration of other planets. Principal investigators are identified for each experiment.

Mcmahan, Tracy↗
NASA NTRS1992

An acoustic charge transport imager for high definition television applications

In this report we present the progress during the second six month period of the project. This includes both experimental and theoretical work on the acoustic charge transport (ACT) portion of the chip, the theoretical program modelling of both the avalanche photodiode (APD) and the charge transfer and overflow transistor and the materials growth and fabrication part of the program.

Hunt, William D.↗
NASA NTRS1992

The continuous plankton recorder survey: A long-term, basin-scale oceanic time series

In the 1920s, before the advent of echo sounders, fishery biologists were greatly concerned with assisting the fisherman to locate schools of pelagic fish. One of the approaches they developed was to relate the distribution of the planktonic food organisms to the presence of the schools of predators such as herring (Clupea harengus). The British planktologist, Alister Hardy, who had already carried out extensive studies on the feeding preferences of herring (Hardy, 1926a), initiated a program to examine the fishermen's contention that herring schools avoided 'green', i.e., phytoplankton-rich, water but could be correlated with high concentrations of zooplankton. This practical program was centered on the use of a specially developed instrument, the 'Plankton Indicator', designed to be used by the fisherman to assist in the search for suitable waters. It had limited success in its main aim but, as a collecting device, it embodied several profoundly important features. It was a simple instrument which was robust enough to be deployed and recovered by the crew of commercial vessels (in this case fishing vessels) while they were underway. The Indicator however, was no more than a high speed net which integrated the plankton over the area of sampling, but Hardy had also become interested in describing the patchiness of planktonic populations. He thus developed the Continuous Plankton Recorder (CPR) where he substituted the fixed filter screen of the Indicator by a continually moving length of silk mesh. The screen traversed at constant speed across the path of the incoming water and the trapped organisms were retained in place by sandwiching beneath an additional second mesh screen. Thus, knowing the speed of the towing vessel and the shooting and hauling positions, the spatial patterns of the plankton could be determined. Hardy took the first CPR to the Antarctic where he used it in the Southern Atlantic (Hardy, 1926b) and later deployed it in the North Sea to make some of the earliest contiguous records of plankton patchiness.

Gamble, John C.↗
NASA NTRS1991

SP-100 high-temperature advanced radiator development

The development of an advanced radiator concept design meeting SP-100 thermoelectric requirements is reported. Carbon-carbon heat pipes are used to produce this lightweight, high-performance radiator. Two feasibility problems had to be solved to enable the design: the production of a carbon-carbon heat pipe tube with integral fins, and the development of a coating that protects the carbon-carbon substrate from 875-K potassium working fluid. Carbon-carbon tubes with integral fins were successfully produced using a T-300 fiber, an angle interlocking weave architecture, and pitch densification. A barrier coating to protect the inside diameter of these tubes which employed the CVD of niobium over a thin rhenium interlayer was developed. The rhenium interlayer proved to be critical to the success of this coating technique by providing a gradation in the coefficient of thermal expansion, carrying a portion of the induced stress load, improving coating adhesion, and providing a partial carbon diffusion barrier.

Rovang, Richard D.↗
NASA NTRS1993

Design of a Hypersonic Waverider-Derived Airplane

The paper describes the first assessment study of a waverider-derived Mach 5 aircraft design using fuselage integrated-underslung over/under turboramjets with endothermic fuel. The study is based on a tanker-to-tanker mission, which begins at Mach 0.8 and 30,000 feet, with the vehicle accelerating to Mach 12 at constant altitude and then to Mach 5 while climbing to about 90,000 feet. The paper describes the vehicle, the aerodynamic analysis, and the propulsion system and its installed performance, structure design, and analysis. The mission simulation was run using the CSOTAV code developed by the NASA Langley Research Center.

Pegg, Robert J.↗
NASA NTRS1992

Aero-space plane figures of merit

The design environment of the aerospace plane is variable rich, intricately networked and sensitivity intensive. To achieve a viable design necessitates addressing three principal elements: knowledge of the 'figures of merit' and their relationships, the synthesis procedure, and the synergistic integration of advanced technologies across the discipline spectrum. This paper focuses on the 'figures of merit' that create the design of an aerospace plane.

Hunt, James L.↗
NASA NTRS1992

Fabrication of carbon-carbon heat pipes for space nuclear power applications

Significant advancements have been made in the development of lightweight, high performance, carbon-carbon heat pipes for space nuclear power applications. The subject program has progressed through the concept definition and feasibility analysis stages to the current test article component fabrication and assembly phase. This concept utilizes a carbon-carbon tube with integrally woven fins as the primary structural element and radiative surface, Nb-1Zr liners to contain a potassium working fluid, and welded end caps and fill tubes. Various tests have been performed in the development of suitable liner bonding techniques and in the assessment of material stability.

Rovang, Richard D.↗
NASA NTRS1992

Modulur DIPS, 2.5-kWe modules for lunar/Mars surface applications, design point selection summary

The results are presented of a systematic series of studies leading to the selection and conceptual design development of a Dynamic Isotope Power System (DIPS) module for lunar and Martian surface applications. An optimum system configuration has been developed for the module that provides a system with a radiator area which is small and manageable without significantly impacting the system mass, efficiency, and technological risk. The maximum design temperature for the system has been determined.

Otting, William D.↗
NASA NTRS1992

Assessment of the US industrial program for AMTEC development

The Alkali Metal Thermal to Electric Converter (AMTEC) is a static energy conversion technology that is expected to provide low mass thermal to electric conversion with efficiencies between 20 and 35 percent. The U.S. program to develop this technology for space power applications has grown substantially over the past 3 years. This expanding program has brought together several laboratories and technical consultants, in separately sponsored projects, to develop the key elements of the technology. An assessment of this multiparty program indicates that, in general, the effort has focused on the high priority technical elements with only moderate overlap between individual projects. There are, however, several areas where additional coordination is needed between major participants in the existing projects, and other areas where new projects should be started, in order to provide reliable space power systems without unnecessary delays.

Sievers, R. K.↗
NASA NTRS1991

Coplanar waveguide microwave filter of YBa2Cu3O7

Thin film low-pass microwave filters have been made with laser-ablated YBa2Cu3O(7-delta) (YBCO) deposited on LaAlO3 substrates, using a coplanar waveguide structure. The coplanar waveguide sections had dimensions suited for integrated circuits. Measured losses in liquid nitrogen were superior to the loss in a similar thin-film copper filter throughout the 0 to 9.5 GHz pass-band. A simple transmission-line model is adequate for filter design using YBCO films with repeatable characteristics. The measured filters demonstrate the performance of fully patterned YBCO after sealing in space-qualifiable hermetic packages. Five packaged filters of this design were delivered to the Naval Research Laboratory as candidates for space flight in the High Temperature Superconductivity Space Experiment.

Chew, Wilbert↗