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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Production of pulsed atomic oxygen beams via laser vaporization methods

The generation of energetic pulsed atomic oxygen beams by laser-driven evaporation of cryogenically frozen ozone/oxygen films and thin indium-tin oxide (ITO) films is reported. Mass spectroscopy is used in the mass and energy characterization of beams from the ozone/oxygen films, and a peak flux of 3 x 10 to the 20th/sq m per sec at 10 eV is found. Analysis of the time-of-flight data suggests that several processes contribute to the formation of the oxygen beam. Results show the absence of metastable states such as the 2p(3)3s(1)(5S) level of atomic oxygen blown-off from the ITO films. The present process has application to the study of the oxygen degradation problem of LEO materials.

Brinza, David E.↗
NASA NTRS1976

Exploratory laser experiments

Experiments are described which were undertaken to explore the application of various dye laser methods for generating laser pulses which could be tuned over H2O absorption lines in the visible and near infrared. Specific topics discussed include: operation of a long pulse dye laser with a tunable, narrow band output at high energies near the 5915 A water vapor absorption bands; assembly and operation of a short duration dye laser near the 5915 A water vapor absorption bands; construction of a dye laser to be pumped to operate in the red and near infrared; and preliminary studies of the beam divergence of the output of the a laser-pumped system. Results are summarized.

Source record↗
NASA NTRS1983

Laser diagnostic methods - A summary

This is a summary and discussion of the state of the art in the use of laser diagnostics in fluid and plasma dynamics. This will encompass: interferometry, scattering, spectroscopy, and velocimetry. Examples of such applications will be provided in the area of fluid dynamics of particle generation and breakup, analysis of three-dimensional density fields, and applications in combustion.

Trolinger, J. D.↗
NASA NTRS1982

A nonintrusive laser interferometer method for measurement of skin friction

A method is described for monitoring the changing thickness of a thin oil film subject to an aerodynamic shear stress using two focused laser beams. The measurement is then simply analyzed in terms of the surface skin friction of the flow. The analysis includes the effects of arbitrarily large pressure and skin friction gradients, gravity, and time varying oil temperature. It may also be applied to three dimensional flows with unknown direction. Applications are presented for a variety of flows including two dimensional flows, three dimensional swirling flows, separated flow, supersonic high Reynolds number flows, and delta wing vortical flows.

Monson, D. J.↗
NASA NTRS1983

A nonintrusive laser interferometer method for measurement of skin friction

A method is described for monitoring the changing thickness of a thin oil film subject to an aerodynamic shear stress using two focused laser beams. The measurement is then simply analyzed in terms of the surface skin friction of the flow. The analysis includes the effects of arbitrarily large pressure and skin friction gradients, gravity, and time varying oil temperature. It may also be applied to three dimensional flows with unknown direction. Applications are presented for a variety of flows, including two dimensional flows, three dimensional swirling flows, separated flow, supersonic high Reynolds number flows, and delta wing vortical flows. Previously announced in STAR as N83-12393

Monson, D. J.↗
NASA NTRS2014

Systems and Methods of Laser Texturing of Material Surfaces and Their Applications

The surface of a material is textured and by exposing the surface to pulses from an ultrafast laser. The laser treatment causes pillars to form on the treated surface. These pillars provide for greater light absorption. Texturing and crystallization can be carried out as a single step process. The crystallization of the material provides for higher electric conductivity and changes in optical and electronic properties of the material. The method may be performed in vacuum or a gaseous environment. The gaseous environment may aid in texturing and/or modifying physical and chemical properties of the surfaces. This method may be used on various material surfaces, such as semiconductors, metals and their alloys, ceramics, polymers, glasses, composites, as well as crystalline, nanocrystalline, polycrystalline, microcrystalline, and amorphous phases.

Gupta, Mool C.↗
NASA NTRS1999

A laser microsurgical method of cell wall removal allows detection of large-conductance ion channels in the guard cell plasma membrane

Application of patch clamp techniques to higher-plant cells has been subject to the limitation that the requisite contact of the patch electrode with the cell membrane necessitates prior enzymatic removal of the plant cell wall. Because the wall is an integral component of plant cells, and because cell-wall-degrading enzymes can disrupt membrane properties, such enzymatic treatments may alter ion channel behavior. We compared ion channel activity in enzymatically isolated protoplasts of Vicia faba guard cells with that found in membranes exposed by a laser microsurgical technique in which only a tiny portion of the cell wall is removed while the rest of the cell remains intact within its tissue environment. "Laser-assisted" patch clamping reveals a new category of high-conductance (130 to 361 pS) ion channels not previously reported in patch clamp studies on plant plasma membranes. These data indicate that ion channels are present in plant membranes that are not detected by conventional patch clamp techniques involving the production of individual plant protoplasts isolated from their tissue environment by enzymatic digestion of the cell wall. Given the large conductances of the channels revealed by laser-assisted patch clamping, we hypothesize that these channels play a significant role in the regulation of ion content and electrical signalling in guard cells.

Non-NASA Center↗
NASA NTRS2010

Creation of High Resolution Terrain Models of Barringer Meteorite Crater (Meteor Crater) Using Photogrammetry and Terrestrial Laser Scanning Methods

Barringer Meteorite Crater or Meteor Crater, AZ, has been a site of high interest for lunar and Mars analog crater and terrain studies since the early days of the Apollo-Saturn program. It continues to be a site of exceptional interest to lunar, Mars, and other planetary crater and impact analog studies because of its relatively young age (est. 50 thousand years) and well-preserved structure. High resolution (2 meter to 1 decimeter) digital terrain models of Meteor Crater in whole or in part were created at NASA Stennis Space Center to support several lunar surface analog modeling activities using photogrammetric and ground based laser scanning techniques. The dataset created by this activity provides new and highly accurate 3D models of the inside slope of the crater as well as the downslope rock distribution of the western ejecta field. The data are presented to the science community for possible use in furthering studies of Meteor Crater and impact craters in general as well as its current near term lunar exploration use in providing a beneficial test model for lunar surface analog modeling and surface operation studies.

Brown, Richard B.↗
NASA NTRS1984

IC Fabrication Methods Improve Laser Diodes

Family of high-performance, tunable diode lasers developed for use as local oscillators in passive laser heterodyne spectrometer. Diodes fabricated using standard IC processes include photolithography, selective etching and vacuum deposition of metals and insulators. Packaging refinements improved thermal-cycling characteristics of diodes and increased room-temperature shelf life.

Miller, M.↗
NASA NTRS1980

Study of LPE methods for growth of InGaAsP/InP CW lasers

Two methods for liquid phase growth of InGaAsP/InP lasers were studied. Single phase growth, based on saturated melts and 5 C supercooling, was compared to two phase growth excess InP and 20 C nominal supercooling. Substrates cut on the (100) plane were used, and morphology in both cases was excellent and comparable to that obtainable in AlGaAs materials. A high degree of reproducibility was obtained in the materials grown by the two phased method, which is therefore presently preferred for the preparation of laser material. A refractive index step of 0.28 and an index n = 3.46 were obtained for In.81Ga.19As,5P5 lasing at 1.3 microns. Oxide-stripe lasers with typical room temperature cw threshold currents of 180 mA were obtained and some of them showed single mode behavior without lateral cavity modifications. COntinuous operation of 800 h at room temperature was obtained without noticeable degradation.

Ladany, I.↗
NASA NTRS1980

Improved thermal-conducting and current-confining film

Ge film that replaces SiO2 coating in method of fabricating room-temperature CW laser diodes achieves greater heat dissipation while maintaining effectiveness as current-confining medium. Film also lessens certain unwanted strain parameters and ultimately increases lifetime of lasers. Method is applicable to fabrication of InP and (AlGa)As CW lasers.

Hawrylo, F. Z.↗
NASA NTRS1985

Lidar profiling of thermodynamic properties of the atmosphere

Principles and applications of pulsed laser methods for temperature, pressure, density, and humidity measurements in the altitude range 0-100 km are discussed. The differential absorption lidar (DIAL) method requires that at least one of the transmitted laser pulses be carefully tuned onto an absorption feature of the species, whereas Raman backscatter methods do not require tunability. OH and Na fluorescence require tuning of the excitation, and are the most suitable methods for high altitude where the atomic and molecular reemission is relatively unquenched by collisions.

Wilkerson, T. D.↗
NASA NTRS1980

Improved degradation resistance of (AlGa)As lasers

Simultaneous doping with Ge and Zn improves degradation resistance of short-wavelength (AlGa)As lasers. Method opens up prospects for greatly increased reliability in lasers and LED's operating at 7,500 angstroms or below.

Kressel, H.↗
NASA NTRS1985

Process research of non-Cz material

Efforts were aimed at achieving a simultaneous front and back junction. Lasers and other heat sources were tried. Successful results were gained by two different methods: laser and flash lamp. Polymer dopants were applied to both sides of dendritic web cells. Rapid heating and cooling avoided any cross contamination between two junctions after removal of the dendrites. Both methods required subsequent thermal annealing in an oven to produce maximum efficiency cells.

Campbell, R. B.↗