A vector solution for electromagnetic wave scattering from a rough surface of arbitrary dielectric constant
Vector solution for electromagnetic wave scattering from rough surface of arbitrary dielectric constant
Kaufman, D. E.↗
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Results for “dielectrics”
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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Bremsstrahlung shielding from electron trapping in dielectrics
Electron trapping in dielectrics, providing effective light and inexpensive spacecraft bremsstrahlung shield and lower average radiation energy at synchronous altitudes
Hollis, D. L.↗
Magnetic field dependence of the dielectric behavior of bound polarons in rutile, TiO2
Two center bound polaron in rutile single crystal, studying dielectric behavior in applied magnetic field
Maccrone, R. K.↗
A continuously variable dielectric phase shifter
Continuously variable microwave stripline phase shifter with linear shift vs frequency by dielectric constant variation
Joines, W. T.↗
Dielectric behavior of lunar samples - Electromagnetic probing of the lunar interior
Dielectric properties of Apollo 12 samples and lunar interior as function of frequency and temperature
Chung, D. H.↗
Method for the solution of electromagnetic scattering problems for inhomogeneous dielectrics as a power series in the ratio /dimension of scatterer//wavelength
Electromagnetic scattering solutions for inhomogeneous dielectrics as power series, using multipoles for far field determination
Von Roos, O.↗
Novel dielectric reduces corona breakdown in ac capacitors
Dielectric system was developed which consists of two layers of 25-gage paper separated by one layer of 50-gage polypropylene to reduce corona breakdown in ac capacitors. System can be used in any alternating current application where constant voltage does not exceed 400 V rms. With a little research it could probably be increased to 700 to 800 V rms.
Loehner, J. L.↗
Handbook of the optical, thermal and mechanical properties of six polycrystalline dielectric materials
The design data for six polycrystalline dielectric materials are presented to describe the optical, thermal, and mechanical properties. The materials are aluminum oxide, calcium fluoride, magnesium fluoride, magnesium oxide, silicon dioxide, and titanium dioxide. The primary interest is in the polycrystalline state, although single crystal data are included when appropriate. The temperature range is room temperature to melting point. The wavelength range is from near ultraviolet to near infrared.
Dewitt, D. P.↗
Dielectric loaded aperture antennas.
This paper describes a primarily experimental study of the effect of placing dielectric obstacles having various geometries directly upon the aperture of circular and rectangular waveguide antennas. It is found that plexiglas spheres, and in some cases plexiglas cubes, one to four wavelengths in dimension, produce directive patterns with low sidelobes. The measured gain in some cases is 6 dB greater than the gain of an optimum horn having an equal aperture size.
Croswell, W. F.↗
A study of the microstructure and optical properties of thin lead-dielectric cermet films
A transmission electron microscopy study involving direct and replicating techniques is directed to a definition of the microstructure of radio frequency-sputtered, thin lead-dielectric cermet films. Once defined, this microstructure is used to obtain theoretical film refractive indices. The Maxwell Garnett theory provides a basis for the theoretical results. Measurements of film transmission and reflectivity are used to obtain rough experimental values for film refractive indices by the Tekucheva method. More exact values are obtained via ellipsometry. The rough Tekucheva values are used to determine the range over which computer calculations interpreting the ellipsometric results must be made. This technique yields accurate values for the film refractive indices.
Owen, R. B.↗
Dynamic measurement of bulk modulus of dielectric materials using a microwave phase shift technique
A microwave Doppler shift technique was developed for measuring the dynamic bulk modulus of dielectric materials such as solid propellants. The system has a demonstrated time resolution on the order of milliseconds and a theoretical spatial resolution of a few microns. Accuracy of the technique is dependent on an accurate knowledge of the wavelength of the microwave in the sample being tested. Such measurement techniques are discussed. Preliminary tests with two solid propellants, one non-aluminized and one containing 16% aluminum, yielded reasonable, reproducible results. It was concluded that with refinements the technique holds promise as a practical means for obtaining accurate dynamic bulk modulus data over a variety of transient conditions.
Barker, B. J.↗
Quantum theory of the dielectric constant of a magnetized plasma and astrophysical applications. I.
A quantum mechanical treatment of an electron plasma in a constant and homogeneous magnetic field is considered, with the aim of (1) defining the range of validity of the magnetoionic theory (2) studying the deviations from this theory, in applications involving high densities, and intense magnetic field. While treating the magnetic field exactly, a perturbation approach in the photon field is used to derive general expressions for the dielectric tensor. Numerical estimates on the range of applicability of the magnetoionic theory are given for the case of the 'one-dimensional' electron gas, where only the lowest Landau level is occupied.
Canuto, V.↗
Investigation of the dielectric waveguide modes in homostructure GaAs laser.
The investigation of the propagation modes in a homostructure GaAs laser and particularly of the spatial displacement of the TE and TM mode is reported. For this investigation, a homostructure GaAs laser was operated in an external optical cavity and experiments were performed where the resonator alignment was varied to displace the image of the p-n junction, formed in the optical cavity, from the p-n junction of the laser diode. The peak power of the laser radiation (which is in the TEM (sub 00) mode), the delay, the optical waveform, and the polarization were measured at room temperature for different cavity alignments. For the evaluation of the propagation modes the experimental results are correlated with the computed field distributions of the modes in a three-layer dielectric waveguide.
Philipp-Rutz, E. M.↗
Lunar permafrost - Dielectric identification.
A simulator of lunar permafrost at 100 K exhibits a dielectric relaxation centered at approximately 300 hertz. If permafrost exists in the moon between 100 and 213 K, it should present a relaxation peak at approximately 300 hertz. For temperatures up to 263 K it may go up to 20 kilohertz.
Alvarez, R.↗
Transmission of isotropic light across a dielectric surface in two and three dimensions.
Average transmittance of polarized diffuse light across a dielectric surface is calculated in both two and three dimensions. The incident light in both cases is confined to an angular range measured from the surface normal. Limiting values in three dimensions correspond to known results for two cases, (1) normal incidence, and (2) diffuse light incident from a 180 deg cone. The two-dimensional formulation is solvable in terms of elliptic functions and incomplete elliptic integrals of the first, second, and third kinds. Results are displayed graphically for values of transmittances in excess of 0.9 associated with relative indices of refraction in the range m = 1.0 to m = 2.6.
Allen, W. A.↗
Interference patterns of a horizontal electric dipole over layered dielectric media.
Interference patterns for electromagnetic fields due to a subsurface reflector below a layered lossy dielectric are calculated with the geometrical optics approximation for use in interpreting data to be collected on the moon by Apollo 17 as well as data currently being obtained on terrestrial glaciers. The radiating antenna lies on the surface. All six field components are calculated and studied. For the endfire solutions, the peak of the first reflected wave is found to be different from that of the broadside ones. To facilitate a physical discussion, we plotted the radiation patterns due to the antenna on the surface.
Tsang, L.↗
TM surface wave diffraction by a truncated dielectric slab recessed in a perfectly conducting surface
The diffraction of a TM sub o surface wave by a terminated dielectric slab which is flush mounted in a perfectly conducting surface is studied. The incident surface wave gives rise to waves reflected and diffracted by the termination; these reflected and diffracted fields may be expressed in terms of the geometrical theory of diffraction by introducing surface wave reflection and diffraction coefficients which are associated with the termination. In this investigation, the surface wave reflection and diffraction coefficients have been deduced from a formally exact solution to this canonical problem. The solution is obtained by a combination of the generalized scattering matrix technique and function theoretic methods.
Pathak, P. H.↗
Thermal properties of dielectric solids below 4 K. I - Polycarbonate
Polymers and other dielectric materials are frequently used for many purposes in the construction of cryogenic apparatus. Yet very few values of the thermal properties of these materials below 4 K have been reported. It is, however, known that one can not use the Debye theory to extrapolate to lower temperatures the measurements of the specific heat capacity above 1 K. The thermal conductivity also follows no theoretically predictable temperature dependence. As a by-product of our studies of the thermal properties of amorphous and partly crystalline materials below 4 K, we wish to report values for the thermal conductivity, specific heat capacity, and velocity of sound below 4 K in materials useful for the construction of cryogenic apparatus. In this article we will describe our measurement techniques and report values for polycarbonate (Lexan). In subsequent notes we will give values for other materials of interest.
Cieloszyk, G. S.↗