Particle size and shape distributions of lunar fines by CESEMI
Particle size and shape distributions of Apollo 12 lunar fines by computer evaluation of scanning electron microscope images
Goerz, H.↗
SEARCH · Engineering Papers
Results for “electron microscope”
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Matrix characteristics and origin of lunar breccia samples no. 12034 and 12073
The transmission electron microscope was used to investigate the nature of the matrix in two samples of lunar breccia. This matrix is composed largely of tiny (0.5 microns) grains of unaltered glass which are plastically fitted against one another, and tightly welded to the clastic fragments with which they are in contact. The breccias have an open framework of angular clastic particles composed mainly of anorthositic, basaltic and glassy fragments. Most of the anorthositic fragments have been shock metamorphosed. Over half of the glassy clasts, and also the former diaplectic glass particles produced from shocked plagioclase, were partly or wholly devitrified before inclusion in the present breccias. It is concluded that each breccia was deposited from a hot basesurge cloud of impact debris, and the tiny bits of glass in the matrix condensed from rock that was volatilized by the heat of major meteorite impact.
Waters, A. C.↗
Preliminary terrestrial based experiments on gravity-affected crystal growth
Tin was melted in a heating assembly secured to the arm of a centrifuge. The furnace was allowed to pivot and reach its equilibrium angle of swing for the gravity force being experienced. The crucible was cooled during rotation to allow the growth of single crystals. The crystals were etched for the purpose of observing the growth striations. Slices were removed from some of the crystals to permit observation of the striations in the interior. Visual analyses were made with a scanning electron microscope. Preliminary conclusions relating the appearance of the striations to gravity forces and the affected growth mechanisms are presented. Further experiments that will verify these conclusions and determine other gravity effects are proposed.
Johnston, M. H.↗
Primary and secondary micrometeoroid impact rate on the lunar surface: A direct measurement
Determination of the number of micrometeoroid impact craters on the camera provided an opportunity to make a sensitive direct measurement of the flux of interplanetary dust particles impacting the lunar surface. Optical and scanning electron microscope studies were performed. Low velocity impact and flux analyses are presented.
Brownlee, D. E.↗
Surface studies on Surveyor 3 tubing sections
Sections C and E of the unpainted, polished aluminum tubing from the strut of the radar altimeter and Doppler velocity sensor were examined in a transmission electron microscope for micrometeorite damage and ion bombardment. Both sections were contaminated and eroded on one side; it is suggested that these conditions were caused by sandblasting by lunar dust and retrorocket plume contamination during Surveyor 3 landing. Microcraters of different configurations were found on the bright sides of the tubes. Several degrees of violence were involved in the formation of the craters, and the particle size could be responsible for some differences. All micropits found were on the bright areas and data indicate 0.2 hypervelocity impact/sq cm and 2/sq cm for other types of craters. The greatest degree of damage resulted from particle impact and was limited to a maximum depth of 2 microns.
Buvinger, E. A.↗
Microcrater investigations on Surveyor 3 material
Screws 9 and 23 from Surveyor 3 were examined with a scanning electron microscope for micrometeorite impact features. Six craters on one of the screws appear to be low velocity impact craters, and a flux for about 0.12 sq cm was calculated to be 0.005/sq m/sec for particle diameter or = 1 micron. Two interpretations are considered: (1) The impacts were produced by interplanetary particles and the flux indicates that deviation from the normal distribution exists only for particles below 1 micron in diameter. (2) Most of the craters were produced by secondary lunar debris, and the flux represents the upper limit for interplanetary particles.
Schneider, E. J.↗
The observation of damage regions produced by neutron irradiation in lithium-doped silicon solar cells.
Study regions of lattice disorder produced in lithium-doped float-zone melted n/p-type silicon solar cells by irradiation with monoenergetic neutrons at doses between 10 to the 10th and 10 to the 13th per cu cm. The defect regions were revealed by chemically etching the surface of the solar cells and by observing carbon replicas in an electron microscope. It was found that the defect density increased with increasing irradiation dose and increased lithium content, whereas the average defect diameter was found to decrease. From thermal annealing experiments it was found that in the lithium-doped material the defect structure was stable at temperatures between 300 and 1200 K. This was found to be in contrast to the undoped material where at the lowest doses considerable annealing was observed to occur. These results are discussed in terms of the theoretical predictions and models of defect clusters proposed by Gossick (1959) and Crawford and Cleland (1959).
Ghosh, S.↗
Analysis of individual particles collected from the stratosphere.
Four classified types of particles in stratospheric balloon collections include chains, aggregates, crystals, and irregular solids which are often liquid coated. An analysis has been made of many individual particles using an X-ray detector on a scanning electron microscope. Chain type particles are composed entirely of elements lighter than sodium. All other particle types are composed mostly of various combinations of the elements Al, Si, Na, K, Ca, Fe, Mg, Ti, and S. The most common element group is Al, Si, Ca or K, and Fe, followed by sulfur or calcium alone. At lower altitudes (12-15 km), liquid is usually associated with the particles and sulfur is prominent. At higher altitudes (23-36 km), liquids and sulfur are usually absent. However, when liquids are occasionally found, so is sulfur. Particles collected with NASA aircraft at 12 km also contain mostly the Al, Si, Ca, Fe element group with associated sulfur, or sulfur alone.
Farlow, N. H.↗
Determination of Burgers vectors in close-packed metals using g.b = 2 contrast.
Reexamination of dislocation images giving double contrast in the electron microscope for g.b = 2 as a possible means for Burgers vector determinations. In fcc foils which have been cut parallel to an active slip plane, the g.b = 2 criterion provides a quick positive Burgers vector analysis which can be carried out during observation. The method is also applicable to basal dislocations in hcp. A comparison between calculated two-beam profiles and experimental images in aluminum is discussed, and several commonly observed characteristics of g.b = 2 contrast are described.
Kestenbach, H.-J.↗
Phase transformations and exsolution in lunar and terrestrial calcic plagioclases.
A coarse domain structure had been discovered in plagioclase in an electron microscopic study of lunar rocks reported by Christie et al. (1971). The domain structures are described in more detail, and their significance in the light of current knowledge concerning the crystal structures of the plagioclases is discussed. An exsolution texture is also described. On the basis of the scale of exsolution it appears that the Apollo 11 and 12 basalts examined cooled more rapidly than the Apollo 14 basalt, which in turn cooled more rapidly than the Stillwater rock.
Heuer, A. H.↗
Electron microscopy - A glimpse into the future.
A forecast attempt is presented on future advances in electron microscopic studies of membrane systems. A review of recent advances and present trends is followed by a discussion of prerequisites to further progress. Special attention is given to research areas of particular promise.
Fernandez-Moran, H.↗
Reliability of hybrid microcircuit discrete components
Data accumulated during 4 years of research and evaluation of ceramic chip capacitors, ceramic carrier mounted active devices, beam-lead transistors, and chip resistors are presented. Life and temperature coefficient test data, and optical and scanning electron microscope photographs of device failures are presented and the failure modes are described. Particular interest is given to discrete component qualification, power burn-in, and procedures for testing and screening discrete components. Burn-in requirements and test data will be given in support of 100 percent burn-in policy on all NASA flight programs.
Allen, R. V.↗
Weldability, strength, and high temperature stability of chemically vapor deposited tungsten
Three types of CVD tungsten (fluoride-produced, chloride-produced and the combination of the two which is termed duplex) were evaluated to determine their weldability, high temperature strength and structural stability during 5000 hour exposure to temperatures of 1540 C and 1700 C. Each type of CVD tungsten could be successfully electron beam welded but the results for the chloride product were not as satisfactory as those of the other two materials. The high temperature strength behavior of the three materials did not differ greatly. However a large difference was noted for the grain growth behavior of the two basic CVD tungsten materials. Fluoride tungsten was found to be relatively stable while for the most part the grain size of chloride tungsten increased appreciably. The examination of freshly fractured surfaces with a scanning electron microscope revealed numerous bubbles in the fluoride material following its exposure to 1700 C for 5000 hours. Less severe thermal treatments produced relatively few bubbles in this material. Only at certain locations within the chloride material associated with the interruption of tungsten were bubbles noted.
Bryant, W. A.↗
Investigation of the plastic fracture of high strength steels
This investigation deals in detail with the three recognized stages of plastic fracture in high strength steels, namely, void initiation, void growth, and void coalescence. The particular steels under investigation include plates from both commercial purity and high purity heats of AISI 4340 and 18 Ni, 200 grade maraging steels. A scanning electron microscope equipped with an X-ray energy dispersive analyzer, together with observations made using light microscopy, revealed methods of improving the resistance of high strength steels to plastic fracture.
Cox, T. B.↗
Cytological studies of lunar treated tissue cultures
An electron microscopic study was made of botanical materials, particularly pine tissues, treated with lunar materials collected by Apollo 12 quarantine mission. Results show unusual structural changes within several of the treated tissues. The bodies, as yet unidentified, resemble virus particles observed within infected plant cells. Although the size and shape of the structures are comparable to rod shaped virus particles such as Tobacco mosaic, the numerical distribution, affinity for stains, and intercellular location are different.
Halliwell, R. S.↗
An Exploratory Study of the Microstructure of Mullite Fibers
The microstructures of mullite composition fibers were examined by transmission electron microscopic techniques and by X-ray diffraction analyses. Both spun and monofilament fiber structures contained little porosity, nor did the degree of porosity change after heating the monofilament to 1205 C for one half hour. Thermal exposure produced crystallite growth and nucleation from the amorphous phase in all three of the spun fibers. After 116 hours at 1426 C, the crystallites of the standard spun fibers became contiguous. In addition, the surface crystallites of these fibers were found to be more than twice as large as the interior crystallites.
Santoro, G.↗
Experimental approaches to well controlled studies of thin-film nucleation and growth.
Particular features and the performance of two experimental systems are described for quantitative studies of thin-film nucleation and growth processes including epitaxial depositions. System I consists of a modified LEED-Auger instrument combined with high-resolution electron microscopy. System II is a UHV electron microscope adapted for in-situ deposition studies. The two systems complement each other ideally, and the combined use of both can result in a comprehensive investigation of vapor deposition processes not obtainable with any other known method.
Poppa, H.↗
Optical computing.
Applications of the optical computer include an approach for increasing the sharpness of images obtained from the most powerful electron microscopes and fingerprint/credit card identification. The information-handling capability of the various optical computing processes is very great. Modern synthetic-aperture radars scan upward of 100,000 resolvable elements per second. Fields which have assumed major importance on the basis of optical computing principles are optical image deblurring, coherent side-looking synthetic-aperture radar, and correlative pattern recognition. Some examples of the most dramatic image deblurring results are shown.
Stroke, G. W.↗