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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 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

The measurement of long period and secular deformation with deep borehole tiltmeters

Two clusters of instruments were emplaced in fractured bedrock in eastern Massachusetts in 1970 and 1975. The intrasite agreement at tidal periods was about two percent, but there is no agreement at longer periods. A strong temperature-induced annual component ranging from 3 to 15 urads was present on instruments installed at depths of 15-20m; it was not apparent on those at 100-120m. One instrument, in continuous operation for three years at 100m, showed a net drift of 0.3 urads down to the SW, with a maximum departure of 2.0 urads from the trend. Pore pressure variations, material corrosion and creep, and local movements are apparently the limiting factors to long-term measurements.

Cabaniss, G. H.↗
NASA NTRS1979

Evaluation of SSME high pressure liquid oxygen turbopump bearings

Examination of the bearings produced conclusive evidence that a very high axial load was applied to bearing 8517903 during a significant portion of the service time. The high loads caused serious ball and race wear and surface fatigue pitting. In all likelihood, continued operation of this bearing with the high axial load would have caused increasing deterioration and catastrophic failure. In contrast, bearing 8517900 showed much less deterioration and probably had experienced only the axial loads deliberately applied by the preload spring. Bearing 8517900 represents the best-case operation with the loads controlled to the levels intended in the design. Fatigue life calculations on bearing 8517903 with an axial load of 27,000 N showed the intolerance of the bearing to such load levels.

Dufrane, K. F.↗
NASA NTRS1979

Flight prototype CO2 and humidity control system

A regenerable CO2 and humidity control system is presently being developed for potential use on shuttle as an alternative to the baseline lithium hydroxide system. The system utilizes a sorbent material (designated HS-C) to adsorb CO2 and the latent heat load from the cabin atmosphere and desorb the CO2 and water vapor overboard when exposed to a space vacuum, thus reducing the overall vehicle heat rejection load. Continuous operation is achieved by utilizing two beds which are alternatively cycled between adsorption and desorption. The HS-C material process was verified. Design concepts for the auxiliary components for the HS-C prototype system were generated. Performance testing verified system effectiveness in controlling CO2 partial pressure and humidity.

Rudy, K. M.↗
NASA NTRS1979

Development of non-volatile semiconductor memory

A 256 word by 8-bit random access memory chip was developed utilizing p channel, metal gate metal-nitride-oxide-silicon (MNOS) technology; with operational characteristics of a 2.5 microsecond read cycle, a 6.0 microsecond write cycle, 800 milliwatts of power dissipation; and retention characteristics of 10 to the 8th power read cycles before data refresh and 5000 hours of no power retention. Design changes were implemented to reduce switching currents that caused parasitic bipolar transistors inherent in the MNOS structure to turn on. Final wafer runs exhibited acceptable yields for a die 250 mils on a side. Evaluation testing was performed on the device in order to determine the maturity of the device. A fixed gate breakdown mechanism was found when operated continuously at high temperature.

Heikkila, W. W.↗
NASA NTRS1979

Design investigation of solar powered lasers for space applications

The feasibility of solar powered lasers for continuous operation in space power transmission was investigated. Laser power transmission in space over distances of 10 to 100 thousand kilometers appears possible. A variety of lasers was considered, including solar-powered GDLs and EDLs, and solar-pumped lasers. An indirect solar-pumped laser was investigated which uses a solar-heated black body cavity to pump the lasant. Efficiencies in the range of 10 to 20 percent are projected for these indirect optically pumped lasers.

Taussig, R.↗
NASA NTRS1978

Storage systems for solar thermal power

A major constraint to the evolution of solar thermal power systems is the need to provide continuous operation during periods of solar outage. A number of high temperature thermal energy storage technologies which have the potential to meet this need are currently under development. The development status is reviewed of some thermal energy storage technologies specifically oriented towards providing diurnal heat storage for solar central power systems and solar total energy systems. These technologies include sensible heat storage in caverns and latent heat storage using both active and passive heat exchange processes. In addition, selected thermal storage concepts which appear promising to a variety of advanced solar thermal system applications are discussed.

Calogeras, J. E.↗
NASA NTRS1978

Study, optimization, and design of a laser heat engine

Laser heat engine concepts, proposed for satellite applications, are analyzed to determine which engine concept best meets the requirements of high efficiency (50 percent or better), continuous operation in space using near-term technology. The analysis of laser heat engines includes the thermodynamic cycles, engine design, laser power sources, collector/concentrator optics, receiving windows, absorbers, working fluids, electricity generation, and heat rejection. Specific engine concepts, optimized according to thermal efficiency, are rated by their technological availability and scaling to higher powers. A near-term experimental demonstration of the laser heat engine concept appears feasible utilizing an Otto cycle powered by CO2 laser radiation coupled into the engine through a diamond window. Higher cycle temperatures, higher efficiencies, and scalability to larger sizes appear to be achievable from a laser heat engine design based on the Brayton cycle and powered by a CO laser.

Taussig, R. T.↗
NASA NTRS1980

Study of LPE methods for growth of InGaAsP/InP CW lasers

Two methods for liquid phase growth of InGaAsP/InP lasers were studied. Single phase growth, based on saturated melts and 5 C supercooling, was compared to two phase growth excess InP and 20 C nominal supercooling. Substrates cut on the (100) plane were used, and morphology in both cases was excellent and comparable to that obtainable in AlGaAs materials. A high degree of reproducibility was obtained in the materials grown by the two phased method, which is therefore presently preferred for the preparation of laser material. A refractive index step of 0.28 and an index n = 3.46 were obtained for In.81Ga.19As,5P5 lasing at 1.3 microns. Oxide-stripe lasers with typical room temperature cw threshold currents of 180 mA were obtained and some of them showed single mode behavior without lateral cavity modifications. COntinuous operation of 800 h at room temperature was obtained without noticeable degradation.

Ladany, I.↗
NASA NTRS1979

Testing Evaluation of the Electrochemical Organic Content Analyzer

The breadboard electrochemical organic content analyzer was evalauted for aerospace applications. An awareness of the disadvantages of expendables in some systems resulted in an effort to investigate ways of reducing the consumption of the analyzer's electrolyte from the rate of 5.17 kg/30 days. It was found that the electrochemical organic content analyzer can result in an organic monitor in the water quality monitor having a range of 0.1 to 100 mg/1 total organic carbon for a large number of common organic solutes. In a flight version it is anticipated the analyzer would occupy .0002 cu m, weigh 1.4 kg, and require 10 W or less of power. With the optimum method of injecting electrolyte into the sample (saturation of the sample with a salt) it would expend only 0.04 kg of electrolyte during 30 days of continuous operation.

Davenport, R. J.↗
NASA NTRS1979

The performance of primary Cs beam clocks using quadrupole and hexapole deflection systems. Consequences for time keeping

Since 1978 the time-and-frequency standard CS1 of the Physikalisch-Technische Bundesanstalt (PTB) has operated continuously as a 'primary clock'. Its uncertainty (7.1 to the negative 15th power) is considerably smaller than that of the other existing primary standards. The CS1 is equipped with a combination of quadrupole and hexapole magnets and uses a longitudinal C-field. Consequences of utilizing primary clocks of this quality for the generation of the International Atomic Time Scale TAI are discussed.

Becker, G.↗
NASA NTRS1980

Reliability improvements in tunable Pb1-xSnxSe diode lasers

Recent developments in the technology of Pb-salt diode lasers which have led to significant improvements in reliability and lifetime, and to improved operation at very long wavelengths are described. A combination of packaging and contacting-metallurgy improvements has led to diode lasers that are stable both in terms of temperature cycling and shelf-storage time. Lasers cycled over 500 times between 77 K and 300 K have exhibited no measurable changes in either electrical contact resistance or threshold current. Utilizing metallurgical contacting process, both lasers and experimental n-type and p-type bulk materials are shown to have electrical contact resistance values that are stable for shelf storage periods well in excess of one year. Problems and experiments which have led to devices with improved performance stability are discussed. Stable device configurations achieved for material compositions yielding lasers which operate continuously at wavelengths as long as 30.3 micrometers are described.

Linden, K. J.↗
NASA NTRS1981

Long life Li/SO2 cells

The development of a long life Li/SO2 battery (one that could operate continuously for periods of at least five years) is discussed. The causes of premature failures in battery concepts are defined and solutions to these problems are described. In particular the corrosion of the glass in a glass-to-metal seal and a spot welded positive lead are addressed.

Levy, S.↗
NASA NTRS1980

Progress in the growth of wide silicon ribbons by the EFG technique at high speed using multiple growth stations

We report here progress in a program designed to examine the feasibility of large scale production of low-cost silicon sheet substrates for solar cells by the EFG process. A multiple-ribbon EFG station, containing five single-ribbon cartridges, has been continuously operated for a period of 15 hours at a duty cycle of 94%. The average width of the ribbon grown was 5 cm, and the average growth speed was 3.4 cm/min. The cartridge concept of ribbon growth has been extended to successfully grow 10 cm wide ribbon at speeds up to 4 cm/min. Large area (approximately 50 sq cm) solar cells with efficiencies in the range from 8% to 11% (AM1) have been made from ribbon grown in the cartridge systems.

Kalejs, J. P.↗
NASA NTRS1980

Four years of zodiacal light observations from the Helios space probes - Evidence for a smooth distribution of interplanetary dust

Zodiacal light experiments on Helios 2 that has been operating continually since January 1976 are discussed, with the purpose of elucidating the distribution of interplanetary dust. Results for the observed gradient of zodiacal light intensity between 1 A.U. and perihelion at 0.3 A.U. show that for all elongations, from 17.5 deg to 135 deg from the sun, the exponent of intensity increase is -2.3 plus or minus 0.1. Color investigations show no systematic variation with heliocentric distance, but a slight reddening is present, increasing towards small elongations. The degree of polarization is found to be higher at 1 A.U. than given previously and decreases towards the sun, even if no correction for electron scattering is made. All results thus fit the hypothesized power law for radial distribution of dust. It is concluded from the stability of zodiacal intensity that the distribution of interplanetary dust is rather simple in space and quite constant in time.

Leinert, C.↗
NASA NTRS1983

Processor Generates and Extracts Silicon

Processor under development continuously generates pure silicon and separates it from reaction by-products. Silicon separator/collector intercepts impinging jet of reaction products and selectively funnels silicon into larger collector. Salt byproduct is removed by tubular condenser held at 1,000 degrees C, and then flows into collector, where it solidifies. Vacuum locks permit periodic salt removal without disturbing continuous operation.

Gould, R. K.↗
NASA NTRS1981

Magnetic Field Investigation for ISEE mother and daughter spacecraft

Highlights of the design and fabrication of fluxgate magnetometers for the ISEE A and B satellites which were launched from a single launch vehicle into the same highly elliptical orbit are presented. The instrument consisted of four basic assemblies: the sensors, the drive and sense electronics, the data handling unit; and the flipper. The digital handling data handling assembly contained a digital filter that mantained a uniform transfer function for all three axes of both spacecraft. Initial studies centered on the bow shock and the magnetopause and show that both boundaries are in rapid motion. The bow shock was found to be very thin, close to an ion inertial length in thickness, but the magnetopause was much thicker than expected, about 400 to 1000 km on average. The magnetometers have each logged over 3 2/3 years of continuous operation.

Russell, C. T.↗
NASA NTRS1982

Concepted design of a surface measurement system for large deployable space antennas

The sensor system is in essence a point design, specifically interfacing with the Harris, Inc., 1000 meter deployable mesh communication antenna. The design can, without large modification, be adapted to other large deployable antennas such as the Lockheed Wrap-rib, the General Dynamics Precision Erectable Truss and the TRW Advanced Sunflower antennas. Measurements are optical displacements. The elements of the system are a central cluster of receivers near the apex of the antenna and active bright targets at the antenna. The cluster defines a single coordinate frame from which all surface positions are referenced. The receivers continuously observe an extended array of sample points located throughout the reflecting surface and its supporting structure. For the Harris antenna, the surface samples are at the mesh gore lines and at the supporting hoop. Output data is in real-time, compatible with on-board processing and active control of antenna figure. Lifetime of the system is at least 10 years continuous operation in space.

Neiswander, R. S.↗
NASA NTRS1981

Sensitivity tests of two-dimensional model predictions of corridor effects

Future aerospace-vehicle systems, such as supersonic transport fleets, the Space Shuttle (SS), and the Heavy-Lift Launch Vehicle (HLLV) system will inject substantial amounts of pollutants into the stratosphere. It is, therefore, pertinent to ask whether the operation of these systems will lead to deleterious effects in the atmosphere. The current investigation is concerned with the development of criteria to assess the likelihood of a detectable corridor effect being caused by the long-term deposition of pollutants at a single latitude. The sources are assumed to operate continuously and at a uniform rate for periods of many years. It is found that transport by meridional winds and by eddy processes acts to diminish the corridor effect by advecting the pollutants out of the region of injection and by mixing them with the ambient air. Attention is given to the altitude for which a detectable corridor effect can be expected for the hypothetical launching of 400 HLLV's per year for 10 years.

Borucki, W. J.↗