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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 415 records · Page 23

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NASA NTRS1973

Mini-Brayton heat source assembly design study. Volume 2: Titan 3C mission

Major conclusions of the space shuttle heat source assembly study are reported that project a minimum weight design for a Titan 3 C synchronous orbit mission; requirements to recover the heat source in orbit are eliminated. This concept permits location of the heat source end enclosure supports and heat source assembly support housing in a low temperature region external to the insulation enclosure and considers titanium and beryllium alloys for these support elements. A high melting insulation blanket consisting of nickel foil coated with zirconia, or of gold foil separated with glass fiber layers, is selected to provide emergency cooling in the range 2000 to 2700 F to prevent the isotope heat source from reaching unsafe temperatures. A graphic view of the baseline heat source assembly is included.

Source record↗

NASA NTRS1976

Design and evaluation of thin metal surface insulation for hypersonic flight

An all-metal insulation was studied as a thermal protection system for hypersonic vehicles. Key program goals included fabricating the insulation in thin packages which are optimized for high temperature insulation of an actively cooled aluminum structure, and the use of state-of-the-art alloys. The insulation was fabricated from 300 series stainless steel in thicknesses of 0.8 to 12 mm. The outer, 0.127 mm thick, skin was textured to accommodate thermal expansion and oxidized to increase emittance. The thin insulating package was achieved using an insulation concept consisting of foil radiation shields spaced within the package, and conical foil supports to carry loads from the skin and maintain package dimensions. Samples of the metal-insulation were tested to evaluate thermal insulation capability, rain and sand erosion resistance, high temperature oxidation resistance, applied load capability, and high temperature emittance.

Miller, R. C.↗

NASA NTRS1976

Nuclear emulsion measurements of the astronauts' radiation exposure on the Apollo-Soyuz mission

On the Apollo-Soyuz mission each astronaut carried one passive dosimeter containing nuclear photographic emulsions, plastic foils, TLD chips, and neutron-activation foils for recording radiation exposure. This report is limited to the presentation of data retrieved from nuclear emulsions. Protons, most of them trapped particles encountered in numerous passes through the South Atlantic Anomaly, contributed by far the largest share to the mission dose. Their linear energy transfer (LET) spectrum was established from track and grain counts in a G.5 emulsion which is used for medium and high energies, and from ender counts in a K.2 emulsion which is used for low energies. The total mission fluence of protons was found to be equivalent to a unidirectional beam of 448,500 square centimeters. The broad spectrum was broken down into small LET intervals, which allowed for the computation of absorbed doses and dose equivalents. The totals are 51 millirad and 74 millirem. Counts of disintegration stars in K.2 emulsion are incomplete at present. While a total of 467 stars were identified, counting their prong numbers is still in progress. It was concluded that the Apollo-Soyuz astronauts' radiation exposure as such did not contain anything out of the ordinary that would seem to require special attention.

Schaefer, H. J.↗

NASA NTRS1976

Molecular effect on equilibrium charge-state distributions

The paper describes an experiment consisting of the acceleration of N(+) and N2(+) ions to energies between 0.25 and 1.75 MeV and their injection through a thin carbon foil, whereupon they were charge-state analyzed with an electrostatic analyzer. A foil-covered electrically suppressed Faraday cup, connected to a stepping motor, moved in the plane of the dispersed beams. The Faraday cup current, which was proportional to the number of incident ions, was sent to a current digitizer and computer programmed as a multiscaler. The energy-dependent charge-state fractions, the mean charge and the distribution width were calculated. It was shown that for incident atoms, the charge state distribution appeared to be spread over more charge states, while for the incident molecules, there was a greater fraction of charge states near the mean charge.

Wickholm, D.↗

NASA NTRS1976

Long lifetime hollow cathodes for 30-cm mercury ion thrusters

An experimental investigation of hollow cathodes for 30-cm Hg bombardment thrusters was carried out. Both main and neutralizer cathode configurations were tested with both rolled foil inserts coated with low work function material and impregnated porous tungsten inserts. Temperature measurements of an impregnated insert at various positions in the cathode were made. These, along with the cathode thermal profile are presented. A theory for rolled foil and impregnated insert operation and lifetime in hollow cathodes is developed. Several endurance tests, as long as 18000 hours at emission currents of up to 12 amps were attained with no degradation in performance.

Mirtich, M. J.↗

NASA NTRS1976

Long lifetime hollow cathodes for 30-cm mercury ion thrusters

An experimental investigation of hollow cathodes for 30-cm Hg bombardment thrusters was carried out. Both main and neutralizer cathode configurations were tested with both rolled foil inserts coated with low work function material and impregnated porous tungsten inserts. Temperature measurements of an impregnated insert at various positions in the cathode were made. These, along with the cathode thermal profile are presented. A theory for rolled foil and impregnated insert operation and lifetime in hollow cathodes is developed. Several endurance tests, as long as 18,000 hours at emission currents of up to 12 amps were attained with no degradation in performance.

Mirtich, M. J.↗

NASA NTRS1977

Measurements of the frequency spectrum of transition radiation

We report a measurement of the frequency spectrum of X-ray transition radiation. X rays were generated by electrons of 5 and 9 GeV in radiators of multiple polypropylene foils, and detected in the range 4 to 30 keV with a calibrated single-crystal Bragg spectrometer. The experimental results closely reproduce the features of the theoretically predicted spectrum. In particular, the pronounced interference pattern of multifoil radiators and the expected hardening of the radiation with increasing foil thickness are clearly observed. The overall intensity of the radiation is somewhat lower than predicted by calculations.

Cherry, M. L.↗

NASA NTRS1977

Spacecraft-produced neutron fluxes on Skylab

Estimates of neutron fluxes in different energy ranges are reported for the Skylab spacecraft. Detectors composed of uranium, thorium, and bismuth foils with mica as a fission track recorder, as well as boron foils with cellulose acetate as an alpha-particle recorder, were deployed at different positions in the Orbital Workshop. It was found that the Skylab neutron flux was dominated by high energy (greater than 1 MeV) contributions and that there was no significant time variation in the fluxes. Firm upper limits of 7-15 neutrons/sq cm-sec, depending on the detector location in the spacecraft, were established for fluxes above 1 MeV. Below 1 MeV, the neutron fluxes were about an order of magnitude lower. The neutrons are interpreted as originating from the interactions of leakage protons from the radiation belt with the spacecraft.

Quist, T. C.↗

NASA NTRS1969

Wind tunnel

A supersonic wind wind tunnel is described for testing several air foils mounted in a row. A test section of a wind tunnel contains means for mounting air foil sections in a row, means for rotating each section about an axis so that the angle of attack of each section changes with the other sections, and means for rotating the row with respect to the air stream so that the row forms an oblique angle with the air stream.

Wilson, E. M.↗

NASA NTRS1979

Onset of condensation effects with an NACA 0012-64 airfoil tested in the Langley 0.3-meter transonic cryogenic tunnel

The onset of condensation effects as determined by varying the stagnation temperature was found to correlate better with the amount of supercooling in the free stream than it did with the supercooling in the region of maximum local Mach number over the air foil. Effects in the pressure distribution over the air foil were seen to appear over its entire length at nearly the same total temperature. Both observations suggest that heterogeneous nucleation does occur in the free stream. The benefits realized from supercooling are presented in terms of increased Reynolds number capability at a given tunnel total pressure and reduced drive-fan power and liquid nitrogen consumption if Reynolds number is held constant. Depending on total pressure and free-stream Mach number, these three benefits are found to vary respectively from 8 to 19 percent, 12 to 24 percent, and 9 to 19 percent. The data analysis and error estimates are given.

Hall, R. M.↗

NASA NTRS1980

Attaching of strain gages to substrates

A method and apparatus for attaching strain gages to substrates is described. A strain gage having a backing plate is attached to a substrate by using a foil of brazing material between the backing plate and substrate. A pair of electrodes that are connected to a current source, are applied to opposite sides of the backing plate, so that heating of the structure occurs primarily along the relatively highly conductive foil of brazing material. Field installations are facilitated by utilizing a backing plate with wings extending at an upward incline from either side of the backing plate, by attaching the electrodes to the wings to perform the brazing operation, and by breaking off the wings after the brazing is completed.

Lemcoe, M. M.↗

NASA NTRS1980

Equations for determining aircraft motions for accident data

Procedures for determining a comprehensive accident scenario from a limited data set are reported. The analysis techniques accept and process data from either an Air Traffic Control radar tracking system or a foil flight data recorder. Local meteorological information at the time of the accident and aircraft performance data are also utilized. Equations for the desired aircraft motions and forces are given in terms of elements of the measurement set and certain of their time derivatives. The principal assumption made is that aircraft side force and side-slip angle are negligible. An estimation procedure is outlined for use with each data source. For the foil case, a discussion of exploiting measurement redundancy is given. Since either formulation requires estimates of measurement time derivatives, an algorithm for least squares smoothing is provided.

Bach, R. E., Jr.↗

NASA NTRS1980

Filter development for the extreme ultraviolet explorer

Thin film filters with extreme ultraviolet bandpasses unattainable with previously available filter materials were developed. Titanium and antimomy were identified as the most promising materials for providing the scientifically important 350-500 A bandpass heretofore unattainable with thin film filters. Titanium foils and titanium-antimony sandwich foils of the required uniformity and durability were fabricated. Transmission measurements and optimization studies indicate that the titanium-antimony combination provides an ideal bandpass for scientifically valuable, high-sensitivity observations with EUVE. Environmental testing of the mechanical strength, moisture sensitivity and aging characteristics of the newly developed filter materials demonstrate flightworthy performance.

Kimble, R.↗

NASA NTRS1979

Solar and terrestrial noble gases in magnetospheric precipitation

Metal-foil collectors were installed on the external structure of Skylab to entrap precipitating magnetospheric particles. The foils were retrieved, and the entrapped helium, neon, and argon were isotopically analyzed in a high-resolution mass spectrometer. Solar and terrestrial helium and neon and terrestrial argon were detected. As expected, the isotopic composition of neon and argon in the high atmosphere was found to be strongly fractionated. Special techniques were used to estimate the initial particle energy of He-3. The measured He-3 flux is consistent with the assumption that precipitating solar He-3 is the major source of terrestrial He-3.

Lind, D. L.↗

NASA NTRS1981

Breakdown voltage of discrete capacitors under single-pulse conditions

For electrostatic capacitors the breakdown voltage is inherently related to the properties of the dielectric, with the important parameters being the dielectric field strength which is related to the dielectric constant and the dielectric thickness. These are not necessarily related to the capacitance value and the rated voltage, but generally the larger values of capacitance have lower breakdown voltages. Foil and wet slug electrolytics can withstand conduction currents pulses without apparent damage (in either direction for foil types). For solid tantalums, damage occurs whenever the capacitor charges to the forming voltage.

Domingos, H.↗

NASA NTRS1980

Structural and compositional characterization of RF sputter-deposited Ni-Cr + Cr2O3 films

An RF-sputtered chrome oxide coating with metallic binders was developed. The chrome oxide coating has high-temperature capabilities and is wear resistant, and has some self-lubricating properties. A nichrome metallic binder was added in the coating to improve its ductility without significant loss in the hardness. The sputtering parameters were optimized to obtain a smooth coating with the maximum adherence. The coatings were applied using bias-sputter and sputter-deposit modes on the heat treated and annealed foil substrates. The coating applied on annealed foils using the sputter-deposit mode was smooth and had the best adherence. Metallurgical examinations showed that the coating was Ni-Cr + Cr2O3. The coating as applied was amorphous and it crystallized during substrate heat treatment.

Bhushan, B.↗

NASA NTRS1981

Deposition of thin insulation layers from the gas phase

The continuous deposition of thin organic dielectric films on metallized carrier foils by glow discharge in monomeric gases is described. Depending on the applied monomers, the films had a dissipation factor of .001 to .003 (1 kHz), a relative permittivity of 2.3 to 2.5 and a resistivity of about 10 to the 17th power omega cm. Additionally, they proved to have a high mechanical homogeneity. Self-healing rolled capacitors with a very high capacitance per volume and of consistently high quality were fabricated from the metallized carrier foils covered with the dielectric film.

Behn, R.↗

NASA NTRS1982

Vacuum tight quartz ampoule for Bridgman growth of crystals with interface demarcation

A growth ampoule for protecting the furnace lining and to prevent a change in the composition of the melt during growth of Pb-T-Te or Ge semiconductors doped with Ga is described. Mo foil is inserted into a quartz tube and sealed at the ends. A vacuum pumping system collapses the tube onto the foil. Spotwelded Mo wires lead in two directions from the collapsed section through quartz capillaries, one of which is also collapsed, on the wire, which provides a contact point for seeded growth of the semiconductor. The ampoule has been used for Bridgeman growth of crystals using a hot zone of 1150 C, with a temperature gradient of 240 C/m, and with current pulses up to 40 A/sq cm.

Crouch, R. K.↗