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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 469 records · Page 26
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Large scale telescopes for high resolution X-ray and gamma-ray astronomy

This paper shows that angular-resolution, energy-range, and structural constraints on image-modulated X-ray telescopes are not fundamental and that the limits on angular resolution can be overcome by constructing such telescopes on a very large spatial scale. It is proposed that widely separated satellites be used for the modulating mask and detector array. Implementation of this concept is discussed in terms of a simple system consisting of a pinhole camera (i.e., a hole in an opaque mask on one subsatellite and a detector array on another). Advantages and problems of such systems are briefly discussed, and a solar X-ray telescope intended for deployment from a Shuttle orbiter is described. It is noted that such large-scale telescopes can be constructed to image gamma rays and even energetic neutrons as well.

Hudson, H. S.↗
NASA NTRS1979

Vapor-deposited graded-thickness films

Rotating substrate and slotted mask allow varying film thickness to be deposited from vapor by exposing film substrate to metal vapor through circular mask. Useful for fabricating variable thickness coatings for controlling thermal, electrical, or other properties.

Herzig, H.↗
NASA NTRS1979

Flight test evaluation of an RAF high altitude partial pressure protective assembly

A partial pressure suit was evaluated during tests in an F-104 and F-15 as a protective garment for emergency descents. The garment is an pressure jerkin and modified anti-g suit combined with an oronasal mask. The garment can be donned and doffed at the aircraft to minimize thermal buildup. The oronasal mask was favored by the pilots due to its immobility on the face during high g-loading. The garment was chosen to provide optimum dexterity for the pilot, which is not available in a full pressure suit, while protecting the pilot at altitudes up to 18,288 meters, during a cabin decompression, and subsequent aircraft descent. During cabin decompressions in the F-104 and F-15, cabin pressure altitude was measured at various aircraft angles of attack, Mach numbers, and altitudes to determine the effect of the aerodynamic slipstream on the cabin altitude.

Ashworth, G. R.↗
NASA NTRS1981

CADAT integrated circuit artwork program

Versatile, ready-to-use program (ARTWORK) converts artwork data into mask patterns. ARTWORK generates signals for controlling mask-fabricating equipment. Extensive utility package enables user to create new pattern libraries, develop and incorporate new cells, and perform systems orientation functions. Program is written in FORTRAN IV.

Kvelthau, R. L.↗
NASA NTRS1980

The automated array assembly task of the low-cost silicon solar array project, phase 2

Several specific processing steps as part of a total process sequence for manufacturing silicon solar cells were studied. Ion implantation was identified as the preferred process step for impurity doping. Unanalyzed beam ion implantation was shown to have major cost advantages over analyzed beam implantation. Further, high quality cells were fabricated using a high current unanalyzed beam. Mechanically masked plasma patterning of silicon nitride was shown to be capable of forming fine lines on silicon surfaces with spacings between mask and substrate as great as 250 micrometers. Extensive work was performed on advances in plated metallization. The need for the thick electroless palladium layer was eliminated. Further, copper was successfully utilized as a conductor layer utilizing nickel as a barrier to copper diffusion into the silicon. Plasma etching of silicon for texturing and saw damage removal was shown technically feasible but not cost effective compared to wet chemical etching techniques.

Coleman, M. G.↗
NASA NTRS1981

Method of making V-MOS field effect transistors utilizing a two-step anisotropic etching and ion implantation

A method of making V-MOS field effect transistors is disclosed wherein a masking layer is first formed over a surface of a crystalline substrate. An aperture is then formed in the masking layer to expose the surface of the substrate. An anisotropic etchant is applied to the exposed surface so that a groove having a decreasing width within increasing depth is formed. However, the etch is not allowed to go to completion with the result that a partially formed V-shaped groove is formed. Ions are accelerated through the aperture for implantation in the crystalline substrate in the lower portion of the partially formed V-shaped groove. Thereafter, an anisotropic etchant is reapplied to the partially formed V-shaped groove, and the etch is allowed to go to completion.

Jhabvala, M. D.↗
NASA NTRS1981

The spectral reflectance of water-mineral mixtures at low temperatures

Laboratory reflectance spectra in the 0.325-2.5 micron region of bound water, water-mineral mixtures, mineral grains on frost, and frost on minerals are presented. The materials used in this study are montmorillonite, kaolinite, beryl, Mauna Kea red cinder, and black charcoal. It is found that the wavelengths of bound water and bound OH absorptions do not shift appreciably with temperature and can be detected when large amounts of free water ice are present. The decrease in the visible reflectance seen in many planetary reflectance spectra containing strong water ice absorptions can be explained by water-mineral mixtures, mineral grains on frost, or frost on mineral grains. Mineral grains on frost are detectable in very small quantities (fractional areal coverage less than approximately 0.005) depending on the mineral reflectance features, while it takes a thick layer of frost (greater than approximately 1 mm) to mask a mineral below 1.4 microns, again depending on the mineral reflectance. Frost on a very dark surface (albedo about 6%) is easily seen; however, a dark mineral mixed with water could completely mask the water absorptions (shortward of 2.5 microns).

Clark, R. N.↗
NASA NTRS1981

Evaporated As2S3 Luneburg lenses for LiNbO3:Ti optical waveguides

Luneburg lenses of good quality were formed on high index optical waveguides by evaporation of arsenic trisulfide glass through simple masks. Using only two thin circular aperture masks, lenses with focal spots of a few times the diffraction limited width at f/4 were obtained. These lenses were designed for and tested at both visible (633 nm) and infrared wavelengths. Procedures for the design, fabrication, and testing of lenses of this type are described.

Busch, J. R.↗
NASA NTRS1982

Surface texturing of fluoropolymers

A method is disclosed for improving surface texture for adhesive bonding, metal bonding, substrate plating, decal substrate preparation, and biomedical implant applications. The surface to be bonded is dusted in a controlled fashion to produce a disbursed layer of fine mesh particles which serve as masks. The surface texture is produced by impinging gas ions on the masked surface. The textured surface takes the form of pillars or cones. The bonding material, such as a liquid epoxy, flows between the pillars which results in a bond having increased strength. For bonding metals a thin film of metal is vapor or sputter deposited onto the textured surface. Electroplating or electroless plating is then used to increase the metal thickness in the desired amount.

Banks, B. A.↗
NASA NTRS1981

Saturn's E ring

Observations of the tenuous E ring of Saturn made by an earth-based CCD system at the time of the ring-plane crossing of March 1980 are presented. The observations were made with the CCD system attached to the 1.8-m Perkins reflector at Lowell Observatory using a pupil mask behind a focal plane mask to suppress telescopic diffraction. Photometric analysis of the CCD images reveal the edge-on brightness profile of the ring, beginning at a distance of 3 Saturn radii, to peak sharply in the vicinity of the orbit of Enceladus at about 4 Saturn radii, then decrease to a distance of over 8 Saturn radii. In addition, beyond Enceladus, the edge-on width of the ring is observed to increase with radial distance, reaching nearly 5 arcsec at 7 Saturn radii. Observations suggest, on the one hand, that the E ring is associated with Enceladus and possibly represents material ejected from the satellite, and on the other, that the ring is at an early stage in its evolution.

Baum, W. A.↗
NASA NTRS1982

Self-heated thermocouples for far-infrared detection

A novel self-heated Bi-Sb thermocouple for far-infrared detection has been developed. The detector is suitable for integration with monolithic antennas and imaging arrays. The device is fabricated in a single photolithography masking step using a photoresist-bridge technique. This bridge technique has also been used to make microbolometers with lower 1/f noise than those made by two conventional masking steps. The thermocouples have a noise equivalent power of 7 x 10 to the -10th W/sq rt of Hz and a 3-dB frequency response of 150 kHz.

Neikirk, D. P.↗
NASA NTRS1982

Process research on non-CZ silicon material

High risk, high payoff research areas associated with he process for producing photovoltaic modules using non-CZ sheet material are investigated. All investigations are being performed using dendritic web silicon, but all processes are directly applicable to other ribbon forms of sheet material. The technical feasibility of forming front and back junctions in non-CZ silicon using liquid dopant techniques was determined. Numerous commercially available liquid phosphorus and boron dopant solutions are investigated. Temperature-time profiles to achieve N(+) and P(+) sheet resistivities of 60 + or - 10 and 40 + or - s10 ohms per square centimeter respectively are established. A study of the optimal method of liquid dopant application is performed. The technical feasibility of forming a liquid applied diffusion mask to replace the more costly chemical vapor deposited SiO2 diffusion mask was also determined.

Source record↗
NASA NTRS1982

New two-dimensional photon camera

A photon-sensitive camera, applicable to speckle imaging of astronomical sources, high-resolution spectroscopy of faint galaxies in a crossed-dispersion spectrograph, or narrow-band direct imaging of galaxies, is presented. The camera is shown to supply 8-bit by 8-bit photon positions (256 x 256 pixels) for as many as 10 to the 6th photons/sec with a maximum linear resolution of approximately 10 microns. The sequence of photon positions is recorded digitally with a VHS-format video tape recorder or formed into an immediate image via a microcomputer. The four basic elements of the camera are described in detail: a high-gain image intensifier with fast-decay output phosphor, a glass-prism optical-beam splitter, a set of Gray-coded masks, and a photomultiplier tube for each mask. The characteristics of the camera are compared to those of other photon cameras.

Papaliolios, C.↗
NASA NTRS1983

An imaging telescope for high energy gamma-ray astronomy

Recent tests of a gamma-ray imaging telescope, which incorporated a coded aperture mask and multiwire proportional counter system produced good images of a tritium target source which was used to generate the 20 MeV protons at a proton Van de Graaff accelerator. This paper indicates what performance might be expected if a large area drift chamber were used in conjunction with a coded aperture mask. The prospects for achieving significant scientific results if such a system were flown on a variety of space vehicles are discussed.

Frye, G.↗
NASA NTRS1983

A two-dimensional photochemical model of the atmosphere. I Chlorocarbon emissions and their effect on stratospheric ozone

A two-dimensional photochemical model is used to examine changes to the ozone layer caused by emissions of CFCl3, CF2Cl2, CH3CCl3 and CCl4. The influence of a possible secular increase in tropospheric methane up to 2 percent per year was found to be small, although it acts to mask decreases in total ozone caused by the chlorocarbons. Increasing NO(x) emissions caused by industralization also tend to mask decreases in total ozone and may have caused total ozone to increase by about 1 percent. The model-calculated ozone decreases are estimated to be about 3 percent by 1980. This estimate is higher than estimates by similar models, although it is noted that CCl4 and CH3CCl3 emissions are included in the model in addition to CFCl3 and CF2Cl2. This is significant because the model indicates that CCl4 has dominated the ozone depletions so far, and knowledge of the historical emission rate of CCl4 to the atmosphere is incomplete. There remain sufficient significant disagreements between theoretical and observed concentrations and variabilities, particularly for odd nitrogen and ClO, to caution against assigning too much confidence in the calculated ozone depletion.

Gidel, L. T.↗
NASA NTRS1982

Development of a tantalum pentoxide Luneberg lens

A process has been developed for the fabrication of a tantalum pentoxide waveguide Luneburg lens as the input collimator for an optical signal processing circuit on a silicon substrate, such as an integrated wavelength demultiplexer. The development of such a lens involved improvement of the deposition mask profile, reduction of surface scattering by underlaying the lens, reduction of edge scattering by using shims under the mask, and prediction and measurement of the TE-TM polarization aberration. It is shown that polarization aberration significantly affects the design of a demultiplexer system.

Bryan, D. A.↗
NASA NTRS1984

Multicolor printing plate joining

An upper plate having ink flow channels and a lower plate having a multicolored pattern are joined. The joining is accomplished without clogging any ink flow paths. A pattern having different colored parts and apertures is formed in a lower plate. Ink flow channels each having respective ink input ports are formed in an upper plate. The ink flow channels are coated with solder mask and the bottom of the upper plate is then coated with solder. The upper and lower plates are pressed together at from 2 to 5 psi and heated to a temperature of from 295 F to 750 F or enough to melt the solder. After the plates have cooled and the pressure is released, the solder mask is removed from the interior passageways by means of a liquid solvent.

Waters, W. J.↗