Annual Progress Report, 1966
Rarefied gas mechanics, plasma dynamics, blast wave phenomena, energy conversion, aerodynamic noise, subsonics, flight dynamics, materials, high altitude measurements, and molecular beams
PLASMA DYNAMICS↗
SEARCH · Engineering Papers
Results for “Wave Energy”
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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Gravitational radiation in the limit of high frequency. II - Nonlinear terms and the effective stress tensor.
HF vacuum gravitational field expansion, discussing nonlinear terms and effective stress tensor for gravitational waves localized energy
Isaacson, R. A.↗
Surface adsorption of light gas atoms
Light gas atoms adsorption on solid surfaces, calculating wave function, energy, mobility, sticking coefficient, etc
Hollenbach, D.↗
The radiation of sound from an engine exhaust
Internal combustion engine exhaust system sound radiation, discussing pressure wave effects, energy flux and boundary conditions
Alfredson, R. J.↗
Alfven waves in spiral interplanetary field
This paper presents a theoretical study of the Alfven waves in the spiral interplanetary magnetic field. The Alfven waves under consideration are arbitrary large-amplitude nonmonochromatic microscale waves of any polarization. They superpose on a mesoscale background flow of thermally anisotropic plasma. When the WKB approximation is used, an analytical solution for the amplitude vectors is obtained as a function of the background flow properties: density, velocity, Alfven speed, thermal anisotropy, and the spiral angle. The relative intensity of fluctuations compared with the magnitude of the background field has its maximum in the region near 1 AU. Thus outside of this region the solar wind is less turbulent. Owing to attenuation of microscale Alfven waves, fluctuation energy is converted into the kinetic energy of the solar wind.
Whang, Y. C.↗
Hybrid theory and calculation of e-N2 scattering
A theory of electron-molecule scattering was developed which was a synthesis of close coupling and adiabatic-nuclei theories. The theory is shown to be a close coupling theory with respect to vibrational degrees of freedom but is a adiabatic-nuclei theory with respect to rotation. It can be applied to any number of partial waves required, and the remaining ones can be calculated purely in one or the other approximation. A theoretical criterion based on fixed-nuclei calculations and not on experiment can be given as to which partial waves and energy domains require the various approximations. The theory allows all cross sections (i.e., pure rotational, vibrational, simultaneous vibration-rotation, differential and total) to be calculated. Explicit formulae for all the cross sections are presented.
Chandra, N.↗
Is there a high frequency limit to laser action
A review and discussion of modern theories and results leads to the conclusion that an absolute upper bound exists to the photon energies for which laser action can occur, and that depending on the laser medium, it lies in the range between 1 and 100 MeV. At higher energies, a wave cannot grow as rapidly as it is depleted. The same restriction applies to frequency conversion devices employing nonlinear interactions.
Baldwin, G. C.↗
Laser aircraft propulsion
The concept of using a high energy continuous wave laser beam from a power satellite in geosynchronous orbit to power a commercial air transport during cruise, i.e., a laser-powered airplane, is examined. These studies indicate that a laser powered airplane is a nearly fuelless and pollution-free flight transportation system which is cost competitive with the fuel conservative air transport of the future. This laser flight system involves the integration of a conventional aircraft with a laser power satellite and a set of laser driven turbofans, all of which can be fabricated with existing or projected technology. The dominant cost of the laser-powered flight transportation system is the cost of the power satellite.
Hertzberg, A.↗
The contribution of the diffuse light component to the topographic effect on remotely sensed data
The topographic effect is measured by the difference between the global radiance from inclined surfaces as a function of their orientation relative to the sensor position and light source. The short wave radiant energy incident on a surface is composed of direct sunlight, scattered skylight, and light reflected from surrounding terrain. The latter two components are commonly known as the diffuse component. The contribution of the diffuse light component to the topographic effect was examined and the significance of this diffuse component with respect to two direct radiance models was assessed. Diffuse and global spectral radiances were measured for a series of slopes and aspects of a uniform and surface in the red and photographic infrared parts of the spectrum, using a nadir pointing two channel handheld radiometer. The diffuse light was found to produce a topographic effect which varied from the topographic effect for direct light. The topographic effect caused by diffuse light was found to increase slightly with solar elevation and wavelength for the channels examined. The correlations between data derived from two simple direct radiance simulation models and the field data were not significantly affected when the diffuse component was removed from the radiances. Radiances from a 60 percent reflective surface, assuming no atmospheric path radiance, the diffuse light topographic effect contributed a maximum range of 3 pixel values in simulated LANDSAT data from all aspects with slopes up to 30 degrees.
Justice, C.↗
Noise suppression characteristics of peripherally segmented duct liners
The acoustic fields and transmission losses produced in semi-infinite circular ducts with peripherally segmented liners are analyzed using a series expansion of hard-wall duct modes. The coefficients of the series are computed using Galerkin's method. Unlike finite element approaches, this analysis includes the effects of realistic sources and the number of peripheral strips need not be small. It is shown that peripherally segmented liners redistribute the acoustic energy in waves composed of only a single circumferential mode at the source into other waves which contain a multitude of circumferential modes in the lined section. The accuracy of eigenfunctions computed from the analysis was observed to increase as either the frequency or radial mode order increased. The transmission losses were found to be accurate at frequencies above the cut-on value of the first-order radial mode in a hard-wall duct. The results show that for plane wave sources, peripherally segmented liners may attenuate as much sound as an optimized uniform liner at the optimal point while giving more noise suppression at most other frequencies.
Watson, W. R.↗
A comparison of solar wind and ionospheric ion acoustic waves
Ion acoustic waves produced during the Trigger experiment are compared to ion acoustic waves observed in the solar wind. After normalizing to the Debye length the spectra are nearly identical, although the ionospheric wave relative energy density is 100 times larger than the solar wind case.
Kintner, P. M.↗
Extended adiabatic blast waves and a model of the soft X-ray background
An analytical approximation is generated which follows the development of an adiabatic spherical blast wave in a homogeneous ambient medium of finite pressure. An analytical approximation is also presented for the electron temperature distribution resulting from coulomb collisional heating. The dynamical, thermal, ionization, and spectral structures are calculated for blast waves of energy E sub 0 = 5 x 10 to the 50th power ergs in a hot low-density interstellar environment. A formula is presented for estimating the luminosity evolution of such explosions. The B and C bands of the soft X-ray background, it is shown, are reproduced by such a model explosion if the ambient density is about .000004 cm, the blast radius is roughly 100 pc, and the solar system is located inside the shocked region. Evolution in a pre-existing cavity with a strong density gradient may, it is suggested, remove both the M band and OVI discrepancies.
Cox, D. P.↗
Possible evidence for coronal Alfven waves
A statistical ray analysis is used to analyze observed electron content and Faraday rotation fluctuations in the 2.29 GHz S band carrier signals of the two Helios spacecraft probing the magnetic and density structures of the solar corona inside 0.05 AU. It is found that (1) the observed Faraday rotation fluctuations cannot be due only to electron density fluctuations in the corona, unless the coronal magnetic field is about five times stronger than suggested by current estimates; and (2) the observed Faraday rotation fluctuations are consistent with the hypothesis that the sun radiates Alfven waves whose energies are great enough to heat and accelerate high-speed solar wind streams.
Hollweg, J. V.↗
Some fundamental concepts in remote sensing
The term remote sensing is defined as well as ideas such as class, pattern, feature, pattern recognition, feature extraction, and theme. The electromagnetic spectrum is examined especially those wavelength regions available to remote sensing. Relevant energy and wave propagation laws are discussed and the characteristics of emitted and reflected radiation and their detection are investigated. The identification of classes by their spectral signatures, the multispectral approach, and the principal types of sensors and platforms used in remote sensing are also considered.
Source record↗
Modal and non-modal baroclinic waves
Solution of the initial-value problem for the Eady model is presented. In the presence of boundaries, normal mode waves as well as non-modal waves exist. Energy extracted from the mean flow during the initial development of a perturbation is found to excite the persistent normal modes. It is suggested that this process may be important to cyclogenesis and in providing energy to neutral or near-neutral normal modes. In particular, the Petterssen criterion for cyclogenesis is clarified.
Farrell, B.↗
Magnetotail flux ropes
The structures of flux ropes in the distant magnetotail are inferred from correlated ISEE-3 wave, high energy particle and electron plasma data from December 1982 through March 1983. The spacecraft was then travelling in a figure-8 pattern which took it into the region between the moon and 230 earth radii. The ropes were identified by a bipolar variation along one magnetic component while the spacecraft was in the north lobe. The double peaked magnetic signature included a strong axial field, a weaker circumferential field, and uniformity across the axis. The rope was imbedded in the lobe fields and contained hot, tailward streaming plasma. Finally, a correlation was derived between the presence of the ropes and a high Kp value.
Sibeck, D. G.↗
Comparison of mesospheric VHF radar echoes and rocket probe electron concentration measurements
Refractive index irregularities in the equatorial mesosphere have been investigated using both the Jicamarca VHF radar and a rocket-borne Langmuir probe launched from Punta Lobos, Peru. On February 27, 1983, a single layer of turbulence was observed in the upper mesosphere by both experiments. There is very good agreement between the observed radar echo power and the radar scattering cross section calculated from the rocket data when these are interpreted in the context of isotropic turbulence. The inner and outer scales of turbulence have been calculated from both the radar and the rocket data, and good agreement is found. The radar data show indications of large-scale vortices in the layer of irregularities. Rocket data show that the inner scale of turbulence in the upper mesosphere is a few tens of meters and that the Jicamarca radar Bragg wavelength (3 m) is well within the viscous subrange of turbulence in this altitude range. The spectral index in the inertial subrange is close to -5/3, changing to about - 7 at higher wave numbers. Energy dissipation rate in the layer was calculated to be 0.05 W/kg, in good agreement with previous estimates.
Royrvik, O.↗
Energy balance constraints on gravity wave induced eddy diffusion in the mesosphere and lower thermosphere
The constraints on turbulence improved by the mesospheric heat budget are reexamined, and the sufficiency of the theoretical evidence to support the hypothesis that the eddy Prandtl number is greater than one in the mesosphere is considered. The mesopause thermal structure is calculated with turbulent diffusion coefficients commonly used in chemical models and deduced from mean zonal wind deceleration. It is shown that extreme mesopause temperatures of less than 100 K are produced by the large net cooling. The results demonstrate the importance of the Prandtl number for mesospheric turbulence.
Strobel, D. F.↗