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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 811 records · Page 45
All sourcesNASA NTRSDOE OSTI
NASA NTRS1971

Measured losses in superconductor magnets for 60-Hertz ac operation.

Results of an experimental study of electrical losses in superconductor magnets. Preliminary 60-Hz ac loss data are presented for coils constructed of Nb3Sn ribbon, Nb-Ti cable, and multifilament Nb-Ti. Losses have been measured for different size coils up to approximately 20 cm in diameter. Of the conductor types tested, Nb3Sn ribbon has the lowest losses for ac operation. In Nb3Sn-ribbon coils of different sizes, the loss per unit length of conductor is shown to decrease with a decrease in the rate of change of current and to increase, in general, with increase in coil size. An important aspect of the study is the high degree of repeatability of the data.

Hamlet, I. L.↗
NASA NTRS1972

Numerical analysis method for linear induction machines.

A numerical analysis method has been developed for linear induction machines such as liquid metal MHD pumps and generators and linear motors. Arbitrary phase currents or voltages can be specified and the moving conductor can have arbitrary velocity and conductivity variations from point to point. The moving conductor is divided into a mesh and coefficients are calculated for the voltage induced at each mesh point by unit current at every other mesh point. Combining the coefficients with the mesh resistances yields a set of simultaneous equations which are solved for the unknown currents.

Elliott, D. G.↗
NASA NTRS1972

Thermal characteristics under load

A theoretical study was made of the temperature profile in a flat conductor cable. The conductor temperature rise was determined under full load and partial load conditions in an air environment as a function of the current. Similar results were obtained for the fully loaded single cable in vacuum and also for the case of one side of the cable in contact with a heat sink. The results are in good agreement with experimental values, where available.

Carlton, R. F.↗
NASA NTRS1972

Electrical impedance of FCC

The electrical characteristics of FCC are investigated in the context of multiple transmission lines theory. Analytical expressions for the coefficients of capacitance of conductors in a single cable are obtained. Numerical values calculated with these expressions are in good agreement with experimental data. Crosstalk, attenuation constants and phase angles of the current and voltage in flat conductor cable are also calculated.

Liu, Y. S.↗
NASA NTRS1972

Energy pulse bonding

To eliminate many of the present termination problems a technique called energy pulse bonding (EPB) was developed. The process demonstrated the capability of: (1) joining conductors without prior removal of insulations, (2) joining conductors without danger of brittle intermetallics, (3) increased joint temperature capability, (4) simultaneous formation of several bonds, (5) capability of higher joint density, and (6) a production oriented process. The following metals were successfully bonded in the solid state: copper, beryllium copper, phosphor bronze, aluminum, brass, and Kovar.

Smith, G. C.↗
NASA NTRS1973

Wide temperature range electronic device with lead attachment

A electronic device including lead attachment structure which permits operation of the devices over a wide temperature range is reported. The device comprises a core conductor having a thin coating of metal thereon whereby only a limited amount of coating material is available to form an alloy which bonds the core conductor to the device electrode, the electrode composition thus being affected only in the region adjacent to the lead.

Farrell, R.↗
NASA NTRS1973

Compact thermoelectric converter systems technology

A schematic of the developed tubular thermoelectric module is shown. It consists of alternate washers of n- and p-type lead telluride, separated by thin natural mica washers. Electrical continuity within the circuit is accomplished by cylindrical conductor rings located at the I.D. and O.D. of the lead telluride washers. The conductor rings are also separated by the same mica which separate the lead telluride washers. The result is a radially serpentine current path along the length of the module. The circuit is isolated from the structural claddings by thin sleeves of boron nitride. Circuit containment and heat transfer surfaces are provided by the inner and outer cladding, heat being transferred from a heat source at the inner clad, conducted radially outward through the lead telluride to the outer clad where the waste heat is removed by a heat rejection system.

Source record↗
NASA NTRS1973

Transparent switchboard

A tin oxide coating is formed on a plate of glass and the coating is then etched away from the glass in thin lines to form separate electrical conductors which extend to one end of the plate and connect to either a vertical (column) or horizontal (row) position sensing SCR circuit. A thin transparent insulating coating is formed over the oxide layer except at selected touch points which are positioned in a matrix pattern of vertical columns and horizontal rows. Touching one of these points with a finger bridges the thin line between adjacent conductors to activate trigger circuits in the particular row and column sensing circuits associated with the point touched. The row and column sensing circuits are similar and are powered with a low frequency, ac voltage source. The source for the row circuits is 180 out of phase with the source for the column circuits so that one circuit acts as ground for the other during half of the supply voltage cycle. The signals from the sensing circuits are input to a logic circuit which determines the presence of a valid touch, stores a binary matrix number associated with the touched point, signals a computer of the presence of a stored number and prevents storage of a new number before receiving an enable signal from the computer.

Rasmussen, H. P.↗
NASA NTRS1974

Design guidelines for advanced LSI microcircuit packaging using thick film multilayer technology

Ceramic multilayer circuitry results from the sequential build-up of two or more layers of pre-determined conductive interconnections separated by dielectric layers and fired at an elevated temperature to form a solidly fused structure. The resultant ceramic interconnect matrix is used as a base to mount active and passive devices and provide the necessary electrical interconnection to accomplish the desired electrical circuit. Many methods are known for developing multilevel conductor mechanisms such as multilayer printed circuits, welded wire matrices, flexible copper tape conductors, and thin and thick-film ceramic multilayers. Each method can be considered as a specialized field with each possessing its own particular set of benefits and problems. This design guide restricts itself to the art of design, fabrication and assembly of ceramic multilayer circuitry and the reliability of the end product.

Peckinpaugh, C. J.↗
NASA NTRS1975

Packaging printed circuit boards: A production application of interactive graphics

The structure and use of an Interactive Graphics Packaging Program (IGPP), conceived to apply computer graphics to the design of packaging electronic circuits onto printed circuit boards (PCB), were described. The intent was to combine the data storage and manipulative power of the computer with the imaginative, intuitive power of a human designer. The hardware includes a CDC 6400 computer and two CDC 777 terminals with CRT screens, light pens, and keyboards. The program is written in FORTRAN 4 extended with the exception of a few functions coded in COMPASS (assembly language). The IGPP performs four major functions for the designer: (1) data input and display, (2) component placement (automatic or manual), (3) conductor path routing (automatic or manual), and (4) data output. The most complex PCB packaged to date measured 16.5 cm by 19 cm and contained 380 components, two layers of ground planes and four layers of conductors mixed with ground planes.

Perrill, W. A.↗
NASA NTRS1976

Urban construction and safety project

Technology utilization projects in the area of urban construction and safety included the following: development of undercarpet and baseboard flat conductor cables, flood insurance studies, tornado safety engineering, the Project TECH house at the Langley Research Center, assistance to the City of Atlanta in their environmental habitability and resource allocation program, and market assessment of a solid state diesel engine controller. The flat conductor cable and the flood insurance studies are given particular attention.

Hogarth, P. T.↗
NASA NTRS1976

External tank gaseous oxygen line simulated lightning tests

Tests were made to evaluate the effects of lightning strikes on the shuttle external tank gaseous oxygen pressurization line. This line, designed to conduct gaseous oxygen may also act as a lightning conductor. Questions have been raised as to the potential hazard of this line as a lightning conductor with speculation as to the damage that might occur to the pressurization line, and the adjacent thermal protective surfaces, from a lightning strike. The region of investigation was from above the cone of the launch tower lightning protection to 15.24 km (50, 000 ft) altitude. Tests were performed on samples of thin wall stainless steel tubing filled with gaseous oxygen under simulated flight conditions. No specimen malfunctions occurred when the tests were conducted according to JSC specifications. Based on the JSC specifications and the results of these tests, it is concluded that a lightning strike will not cause a malfunction of the shuttle external tank gaseous oxygen line made of the representative material tested.

Smith, H. E.↗
NASA NTRS1975

Contamination control coatings for hybrids

Conductive particles unexpectedly present in hermetically sealed hybrid microcircuit packages pose a high risk of shorting the closely spaced planar conductors within the package, causing failure of the device. The present work evaluates commercially available organic coating materials and determines the most promising ones for protection of complex microcircuits against entrapped particulate contaminants. The candidate materials were exposed to a series of physical and electrical screening tests, the results of which were used as a basis for the final coating selection. Silicones and high-purity epoxies are found to not only display excellent compatibility with microcircuits but to improve the performance of microcircuits as to voltage breakdown between adjacent conductors.

Mastro, A. R.↗
NASA NTRS1979

Eliminating gold migration in microcircuits

Report discusses how effects of moisture and other factors causing bridging between conductors can be prevented. Study details how several factors such as contaminants, large packages, high voltage, narrow conductor spacing and temperature contribute to moisture problems.

Dermarderosian, A.↗
NASA NTRS1978

Cryogenic-coolant He-4-superconductor interaction

The thermodynamic and thermal interaction between a type 2 composite alloy and cryo-coolant He4 was studied with emphasis on post quench phenomena of formvar coated conductors. The latter were investigated using a heater simulation technique. Overall heat transfer coefficients were evaluated for the quench onset point. Heat flux densities were determined for phenomena of thermal switching between a peak and a recovery value. The study covered near saturated liquid, pressurized He4, both above and below the lambda transition, and above and below the thermodynamic critical pressure. In addition, friction coefficients for relative motion between formvar insulated conductors were determined.

Caspi, S.↗
NASA NTRS1977

Ceramic/metal seals

Design criteria are discussed for a hermetic seal capable of withstanding the 450 C operating temperature of a lithium-metal sulfide battery system. A mechanical seal consisting of two high strength alloy metal sleeves welded or brazed to a conductor assembly and pressed onto a ceramic is described. The conductor center passes through the ceramic but is not sealed to it. The seal is effected on the outside of the taper where the tubular part is pressed down over and makes contact.

Bredbenner, A. M.↗
NASA NTRS1980

Analysis and measurements of low frequency lightning component penetration through aerospace vehicle metal and graphite skins

An analysis of the shielding properties of mixed metal and graphite composite structures has illustrated some important aspects of electromagnetic field penetration into the interior. These include: (1) that graphite access doors on metallic structures will attenuate lightning magnetic fields very little; conversely, metal doors on a graphite structure will also attenuate fields from lightning strike currents very little, i.e., homogeneity of the shield is a critical factor in shielding and (2) that continuous conductors between two points inside a graphite skin such as an air data probe metallic tubing connection to an air data computer can allow large current penetrations into a vehicle interior. The true weight savings resulting from the use of composite materials can only be evaluated after the resulting electromagnetic problems such as current penetrations have been solved, and this generally requires weight addition in the form of cable shields, conductor bonding or external metallization.

Robb, J. D.↗
NASA NTRS1980

Cryogenic-coolant He4-superconductor dynamic and static interactions

A composite superconducting material (NbTi-Cu) was evaluated with emphasis on post quench solid cooling interaction regimes. The quasi-steady runs confirm the existence of a thermodynamic limiting thickness for insulating coatings. Two distinctly different post quench regimes of coated composites are shown to relate to the limiting thickness. Only one regime,, from quench onset to the peak value, revealed favorable coolant states, in particular in He2. Transient recovery shows favorable recovery times from this post quench regime (not drastically different from bare conductors) for both single coated specimens and a coated conductor bundle.

Caspi, S.↗