Measured optical absorption coefficients for uranium plasmas
Absolute emissivities of uranium plasmas in gas driven shock tube
Miller, M. H.↗
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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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Optical measurement of multiplume interaction Final report
Laser velocimeter tests in supersonic tunnels and flowfield characteristics in base flow region of Saturn 2 type clustered nozzle configuration
Craven, C. E.↗
Optical measurement of static temperature and hydroxyl radical profiles in a hydrogen-fueled supersonic combustor
Profiles of static temperature and hydroxyl radical concentration were measured in a two-dimensional supersonic combustor test section 22.8 cm downstream of hydrogen injection. A high-pressure gas generator supplied vitiated air to the test section at Mach 2.44, atmospheric pressure, and a total temperature of about 2240 K. Room-temperature hydrogen was injected through a 0.40-cm step slot at Mach 1 and matched pressure. The measurements utilized a noninterfering spectral line absorption technique in which narrow ultraviolet emission lines of the hydroxyl electronic transition are absorbed by the broader absorption lines in the combustion gas. Comparison of the measured temperature profiles with theoretical calculations showed good agreement.
Gaugler, R. E.↗
Optical measurement of interplanetary particulates from Pioneer 10
The spatial concentration and size distribution for particulates measured in situ by the asteroid/meteoroid detector on Pioneer 10 between 1.0 and 3.5 AU are presented. The size distribution includes particles of radii from about 35 microns to 10 cm. Extrapolation from the smallest particle sizes measured shows good agreement with the results of the particle penetration detector carried on the same spacecraft. Within the uncertainties of this experiment, a single size distribution seems appropriate for all but the smallest particles measured. There is evidence for the existence of a planetary sweeping effect in the vicinity of the Mars orbit. As calculated from the particle spatial distribution, the zodiacal light brightness is found to vary approximately as the inverse square of solar distance out to about 2.25 AU and then decrease more rapidly. The absolute value of the zodiacal light brightness as calculated from the particle spatial concentration is found to be too high by a factor of 10.
Soberman, R. K.↗
Particle and optical measurements in the magnetic noon sector of the auroral oval
Simultaneous airborne photometric and satellite particle measurements in the mid-day sector of the auroral oval, around magnetic local noon, are presented. The two sets of measurements are employed independently to delineate various magnetospheric boundaries. The results derived from the particle measurements are compared with those from the photometric observations to assess the reliability of the photometric technique in identifying various magnetospheric regions.
Sivjee, G. G.↗
High-resolution optical measurements of atmospheric winds from space. I - Lower atmosphere molecular absorption
A high-resolution spectroscopic technique, analogous to that used in the thermosphere to measure the vector wind fields in the upper troposphere and stratosphere, is described which uses narrow features in the spectrum of light scattered from the earth's lower atmosphere to provide Doppler information on atmospheric scattering and absorption. It is demonstrated that vector winds can be measured from a satellite throughout the lower atmosphere, using a multiple-etalon Fabry-Perot interferometer of modest aperture. It is found that molecular oxygen and water vapor absorption lines in the spectrum of sunlight scattered by the atmosphere are Doppler-shifted by the line of sight wind, so that they may be used to monitor the global wind systems in the upper troposphere and stratosphere.
Hays, P. B.↗
Optical Measurement of Particle Size and Velocity
Dual-beam laser-Doppler anemometers simultaneously determine velocity and size distribution of particles in flowing fluid.
Smith, J. L.↗
Optical measurement of the velocity of dielectric surface arcs
Surface flashover arc discharge velocities on electron-beam-charged polymer sheets have been measured directly by detecting the light emitted at two points along a straight arc and measuring the time interval between light pulses. For Mylar, the average velocity is 1.2 x 10 to the 6th m/s, and for Teflon the average velocity is approximately 7.3 x 10 to the 5th m/s independent of sheet thickness. These velocities are about two to four times higher than previous measurements. The techniques employed to produce single, straight surface arcs are described.
Balmain, K. G.↗
Optical measurements of fluctuating temperatures in a supersonic turbulent flow using one- and two-photon, laser-induced fluorescence
A laser-induced fluorescence technique was developed that provides a practical means of nonintrusively measuring the instantaneous temperatures in low-temperature turbulent flows. The capabilities of the method are reviewed, and its application to a simple, two-dimensional, turbulent boundary-layer flow at Mach 2 is reported. Measurements of the average temperature distribution through the boundary layer and the magnitudes of temperature fluctuations about their average values are presented.
Gross, K. P.↗
Optical measurements of fluctuating temperatures in a supersonic turbulent flow using one- and two-photon, laser-induced fluorescence
A laser-induced fluorescence technique has been developed that provides a practical means of nonintrusively measuring the instantaneous temperatures in low-temperature turbulent flows. The capabilities of the method are reviewed, and its application to a simple, two-dimensional, turbulent boundary-layer flow at Mach 2 is reported. Measurements of the average temperature distribution through the boundary layer and the magnitudes of temperature fluctuations about their average values are presented.
Gross, K. P.↗
An optical measurement of the population inversion of the ground state Lambda doublet of interstellar CH
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Jura, M.↗
Assessment of the biophysical characteristics of rangeland community using scatterometer and optical measurements
Research activities for the following study areas are summarized: single scattering of parallel direct and axially symmetric diffuse solar radiation in vegetative canopies; the use of successive orders of scattering approximations (SOSA) for treating multiple scattering in a plant canopy; reflectance of a soybean canopy using the SOSA method; and C-band scatterometer measurements of the Konza tallgrass prairie.
Kanemasu, E. T.↗
Research and development of optical measurement techniques for aerospace propulsion research: A NASA Lewis Research Center perspective
The applied research effort required to develop new nonintrusive measurement techniques capable of obtaining the data required by aerospace propulsion researchers and of operating in the harsh environments encountered in research and test facilities is discussed and illustrated through several ongoing projects at NASA's Lewis Research Center. Factors including length of development time, funding levels, and collaborative support from fluid-thermal researchers are cited. Progress in developing new instrumentation via a multi-path approach, including NASA research, grant, and government-sponsored research through mechanisms like the Small Business Innovative Research program, is also described.
Lesco, Daniel J.↗
Upper atmosphere research: Reaction rate and optical measurements
The objective is to provide photochemical, kinetic, and spectroscopic information necessary for photochemical models of the Earth's upper atmosphere and to examine reactions or reactants not presently in the models to either confirm the correctness of their exclusion or provide evidence to justify future inclusion in the models. New initiatives are being taken in technique development (many of them laser based) and in the application of established techniques to address gaps in the photochemical/kinetic data base, as well as to provide increasingly reliable information.
Stief, L. J.↗
Optical Measurements on Solid Specimens of Solid Rocket Motor Exhaust and Solid Rocket Motor Slag
Samples of aluminum slag were investigated to aid the Earth Science and Applications Division at the Marshall Space Flight Center (MSFC). Alumina from space motor propellant exhaust and space motor propellant slag was examined as a component of space refuse. Thermal emittance and solar absorptivity measurements were taken to support their comparison with reflectance measurements derived from actual debris. To determine the similarity between the samples and space motor exhaust or space motor slag, emittance and absorbance results were correlated with an examination of specimen morphology.
Roberts, F. E., III↗
Experiments on the enhancement of compressible mixing via streamwise vorticity. I - Optical measurements
The present study was initiated in an attempt to increase the compressible mixing rate of a supersonic jet injected into a co-flowing supersonic stream by adding streamwise vorticity to the injected flow. This flowfield was imaged using the planar laser scattering technique, and mixing rates were derived entirely from captured images. The results of this image analysis indicate that increases in mixing rate of up to 60 percent are possible through the addition of streamwise vorticity. Furthermore, the degree of mixing enhancement appears to be dependent on the amount of swirl added. Analysis of the instantaneous turbulent structure suggests that this increase in mixing is due to a modification of the largest turbulent structures in the mixing layer.
Naughton, J. W.↗
Optical Measurement Of Propfan Deflections
Optoelectronic system measures deflections of rotating propfan. In addition to 0.5-mW HeNe lasers, system includes Schottky-barrier photodetectors, neutral-density filters, signal amplifiers, output-signal-recording device, and digitizer. Laser beam passes through plane of rotation of propfan blades. Beam is one of three that measure displacements at different blade sections. Additional laser beam at bottom generates shaft-rotation timing signal.
Ramsey, John K.↗
Optical Measurement of the Speed of Sound in Air Over the Temperature Range 300-650 K
Using laser-induced thermal acoustics (LITA), the speed of sound in room air (1 atm) is measured over the temperature range 300-650 K. Since the LITA apparatus maintains a fixed sound wavelength as temperature is varied, this temperature range simultaneously corresponds to a sound frequency range of 10-15 MHz. The data are compared to a published model and typically agree within 0.1%-0.4% at each of 21 temperatures.
Hart, Roger C.↗