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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 649 records · Page 36
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Fast ion transport in silver halide solid solutions and multiphase systems

The incorporation of homovalent ions, e.g., I(-) in AgBr, leads to a substantial increase in ionic conductivity sigma. The charge compensation concept does not explain the enhancement. AgBr + 30 mol. % AgI exhibits sigma approximately 7/omega/cm at 380 C, which is approximately 170% larger than that of alpha-AgI, the best known superionic conductor, at its melting point. The purely elastic displacement caused by the foreign ion is suggested to be the origin of such a unique behavior. Furthermore, AgI-AgBr two-phase systems display sigma approximately 10 to the 3rd times higher than predicted by the classical theories.

Shahi, K.↗
NASA NTRS1980

The reverse laser drilling of transparent materials

Within a limited range of incident laser-beam intensities, laser drilling of a sapphire wafer initiates on the surface of the wafer where the laser beam exits and proceeds upstream in the laser beam to the surface where the laser beam enters the wafer. This reverse laser drilling is the result of the constructive interference between the laser beam and its reflected component on the exit face of the wafer. Constructive interference occurs only at the exit face of the sapphire wafer because the internally reflected laser beam suffers no phase change there. A model describing reverse laser drilling predicts the ranges of incident laser-beam intensity where no drilling, reverse laser drilling, and forward laser drilling can be expected in various materials. The application of reverse laser drilling in fabricating feed-through conductors in silicon-on-sapphire wafers for a massively parallel processer is described.

Anthony, T. R.↗
NASA NTRS1980

Nordheim-Gorter like behavior and one carrier conduction in a quasi-one-dimensional system

A linear correlation has been observed between the thermopower and the conductivity in the high-temperature state (T greater than 220 K) of the TTF halide and pseudohalide salts. It is suggested that this correlation indicates conduction by a single type of carrier under two types of scattering and represents the first reported extension of the Nordheim-Gorter behavior to any quasi-one-dimensional conductor.

Datta, T.↗
NASA NTRS1981

Experimental simulation of space plasma interactions with high voltage solar arrays

Operating high voltage solar arrays in the space environment can result in anomalously large currents being collected through small insulation defects. Tests of simulated defects have been conducted in a 45-cm vacuum chamber with plasma densities of 100,000 to 1,000,000/cu cm. Plasmas were generated using an argon hollow cathode. The solar array elements were simulated by placing a thin sheet of polyimide (Kapton) insulation with a small hole in it over a conductor. Parameters tested were: hole size, adhesive, surface roughening, sample temperature, insulator thickness, insulator area. These results are discussed along with some preliminary empirical correlations.

Stillwell, R. P.↗
NASA NTRS1981

Heat flow from Io /JI/

The existing ground-based measurements of Io's thermal emission at infrared wavelengths of 8.4, 10.6, and 21 microns have been reexamined. Present in these data is the signature of hot spots, presumably similar to the hot spots seen by the IRIS experiment on Voyager. It is possible to extract from these data the total amount of power radiated. Since the hot spots are believed to be a result of deep-seated activity in Io and since the remainder of Io's surface is an extraordinarily poor thermal conductor, the power radiated by the hot spots is essentially the total heat flow. The analysis yields a heat flow of 2 + or - 1 W/sq m. This value is tremendously large in comparison to the average heat flow of the earth (0.06 W/sq m) and the moon (0.02 W/sq m), but is characteristic of active geothermal areas on the earth. A heat flow this large requires that the interior of Io be at least partially molten on a global scale.

Matson, D. L.↗
NASA NTRS1981

Ignitor plug erosion and arc initiation processes in a one-millipound pulsed plasma thruster

The results are presented of a one-millipound pulsed plasma ignition system study. The preliminary data indicate that inductively coupling the ignition plug cathode to the thruster cathode is more beneficial to ignitor plug longevity than resistive coupling. These benefits arise from the ability of the coupling conductor to control the build-up of a carbonaceous deposit on the plug face. The deposit build-up is a strong function of the peak coupling current experienced during thruster operation. The relationship between the ignitor plug discharge and thruster discharge is shown to be very complex with equivalent circuit elements which are dynamic in nature. A preliminary representation of this equivalent circuit is developed.

Aston, G.↗
NASA NTRS1982

Electrical Connector for Graphite Heating Elements

Connection method applies force to two interfaces: that between heating element proper and heating-element support members and between heating-element support members and metal conductor. Inner rod of new connector system is maintained in tension by a spring (for example, Belleville washers). Connection is sufficiently complaint so tension remains within desired range, regardless of thermal expansion and contraction of various elements.

Mackintosh, B. H.↗
NASA NTRS1982

Extracting Silicon From Sodium-Process Products

New acid leaching process purifies silicon produced in reaction between silicon fluoride and sodium. Concentration of sodium fluoride and other impurities and byproducts remaining in silicon are within acceptable ranges for semi-conductor devices. Leaching process makes sodium reduction process more attractive for making large quantities of silicon for solar cells.

Kapur, V.↗
NASA NTRS1982

Glass for Solid State Devices

Glass film has low intrinsic compressive stress for isolating active layers of magnetic-bubble and other solid-state devices. Solid-state device structure incorporates low-stress glasses as barrier and spacer layers. Glass layers mechanically isolate substrate, conductor, and nickel/iron layers.

Bailey, R. F.↗
NASA NTRS1983

Tangleproof Rotary Electrical Coupling

New rotary coupling connects large number of electrical cables to turntable without stressing cables or tangling them. Device accommodates 246 cables containing total of 758 conductors and allows turntable to rotate through arc of 320 degrees. At extremes of rotation, cables are loose enough that they are not pulled taut and overstressed. At halfway point, cables are not so loose that they become entangled.

Keller, F.↗
NASA NTRS1983

Preventing Freezeup in Silicon Ribbon Growth

Carefully-shaped heat conductor helps control thermal gradients crucial to growth of single-crystal silicon sheets for solar cells. Ends of die through which silicon sheet is drawn as ribbon from molten silicon. Profiled heat extractor prevents ribbon ends from solidifying prematurely and breaking.

Mackintosh, B.↗
NASA NTRS1980

Numerical simulation of plasma insulator interactions in space. Part 1: The self consistent calculation

A computer program is being developed to simulate the interaction of a plasma with a conducting disk partially covered by an insulator. Initial runs consider only charge sticking to the dielectric. Results indicate that the current density drawn by the hole in the dielectric increases approximately linearly with voltage for conductor voltages between 5 volts and 250 volts.

Nonnast, J. H.↗
NASA NTRS1982

DSCS 3 life test progress report

Life test considerations for a spacecraft power supply system, a battery system, designed for synchronous communication satellites for the Defense Satellite Communication System are described. The following equipment specifications considered in the life tests were: the nickel cadmium cells; bus conductors; diodes; battery casings; electric discharges; voltage drops; pressure, and temperature measurements. Battery performance data collected during eclipse periods is presented in tabular form.

Thierfelder, H. E.↗
NASA NTRS1981

A Module Experimental Process System Development Unit (MEPSDU)

The development of a cost effective process sequence that has the potential for the production of flat plate photovoltaic modules which meet the price goal in 1986 of 70 cents or less per Watt peak is described. The major accomplishments include (1) an improved AR coating technique; (2) the use of sand blast back clean-up to reduce clean up costs and to allow much of the Al paste to serve as a back conductor; and (3) the development of wave soldering for use with solar cells. Cells were processed to evaluate different process steps, a cell and minimodule test plan was prepared and data were collected for preliminary Samics cost analysis.

Source record↗
NASA NTRS1982

The stress system generated by an electromagnetic field in a suspension of drops

The stress generated in a suspension of drops in the presence of a uniform electric field and a pure straining motion, taking into account that the magnetohydrodynamic effects are dominant was calculated. It was found that the stress generated in the suspension depended on the direction of the applied electric field, the dielectric constants, the vicosity coefficients, the conductivities, and the permeabilities of fluids inside and outside the drops. The expression of the particle stress shows that for fluids which are good conductors and poor dielectrics, especially for larger drops, magnetohydrodynamic effects end to reduce the dependence on the direction of the applied electric field.

Erdogan, M. E.↗
NASA NTRS1982

Electric and magnetic fields

A number of energy momentum anomalies are described that result from the use of Abraham-Lorentz electromagnetic theory. These anomalies have in common the motion of charged bodies or current carrying conductors relative to the observer. The anomalies can be avoided by using the nonflow approach, based on internal energy of the electromagnetic field. The anomalies can also be avoided by using the flow approach, if all contributions to flow work are included. The general objective of this research is a fundamental physical understanding of electric and magnetic fields which, in turn, might promote the development of new concepts in electric space propulsion. The approach taken is to investigate quantum representations of these fields.

Kaufman, H. R.↗
NASA NTRS1982

Component technology for space power systems

The Lewis/OAST program for the development of Component Technology for Space Power Systems is described. The program is divided into five generic areas: semiconductor devices (transistors, thyristors, and diodes); conductors (materials and transmission lines); dielectrics; magnetic devices; and thermal control devices. Examples of progress in each of the five areas is discussed. Bipolar power transistors up to 1000 V at 100 A with a gain of 10 and a 0.5 mu sec rise and fall time are presented. A new class of semiconductor devices with a possibility of switching 1000 000 V is described. Several 100 kW rotary power transformer designs and a 25 kW, 20 kHz transformer weighting 3.2 kg have been developed. Progress on the creation of diamond-like films for thermal devices and intercalated carbon fibers with the strength of steel and the conductivity of copper at one third the mass of copper is presented.

Finke, R.↗
NASA NTRS1982

Validation of the NASCAP model using spaceflight data

The NASA Charging Analyzer Program (NASCAP) has been validated in a space environment. Data collected by the SCATHA (Spacecraft Charging at High Altitude) spacecraft has been used with NASCAP to simulate the charging response of the spacecraft ground conductor and dielectric surfaces with considerable success. Charging of the spacecraft ground observed in eclipse, during moderate and severe substorm environments, and in sunlight has been reproduced using the code. Close agreement between both the currents and potentials measured by the SSPM's, and the NASCAP simulated response, has been obtained for differential charging. It is concluded that NASCAP is able to predict spacecraft charging behavior in a space environment.

Stannard, P. R.↗