Propagation in ferrite-filled coaxial transmission lines.
Dispersion relations for propagation of quasi-TEM mode and higher order symmetric modes in longitudinally magnetized ferrite filled coaxial waveguide
Mueller, R. S.↗
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The influence of air-gap tolerances on the admittance of a dielectric-coated slot antenna.
Air gap tolerances effect on admittance of TEM mode dielectric and plasma coated slot antennas determined by variational method
Jones, J. E.↗
Reflection coefficient of a parallel-plate waveguide illuminating a conducting sheet.
TEM mode reflection coefficient for symmetric parallel plate waveguide composed of adjacent conducting wedges composition and radiating into perfectly reflecting sheet
Burnside, W. D.↗
Aperture radiation from an axially slotted elliptical conducting cylinder using geometrical theory of diffraction.
Equatorial radiation pattern of parallel plate TEM mode axial slot on elliptical conducting cylinders, using wedge diffraction and creeping wave theory
Balanis, C. A.↗
Application of a surface integration technique to parallel-plate waveguide radiation-pattern analysis.
Surface integration technique used in conjunction with wedge diffraction theory to analyze TEM radiation patterns of parallel plate waveguides
Pelton, E. L.↗
Parametric wave amplification and mixing in the ionosphere
Ionospheric parametric amplification and frequency mixing due to polarized TEM waves nonlinear interaction with longitudinal electrostatic waves
Crawford, F. W.↗
Deformation of lunar and terrestrial minerals.
The deformation substructures observed by TEM in breccia returned by the Apollo 14 mission are illustrated and their significance is discussed in the context of earlier work on mineral deformation. Shock-produced glass and heavily deformed mineral grains indicate severe shock deformation. Extensive local recovery and sub-microscopic recrystallization are evident and suggest that the coherency of the breccias is caused by a 'shock sintering' mechanism.
Christie, J. M.↗
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.↗
Diffraction theory techniques applied to aperture antennas on finite circular and square ground planes
Expressions which represent the elevation-plane patterns of a large TEM mode coax aperture and a TM-01 mode circular aperture on finite circular and square ground planes have been derived using geometrical theory of diffraction; design curves for the coax case are presented. The expressions for the field pattern were obtained by superposing the infinite ground plane solutions, the first-order diffracted field solutions, and the axial caustic solutions in their respective regions of validity. The pattern analyses for the coax and circular apertures are verified experimentally.
Cockrell, C. R.↗
Optical antenna gain. I - Transmitting antennas
The gain of centrally obscured optical transmitting antennas is analyzed in detail. The calculations, resulting in near- and far-field antenna gain patterns, assume a circular antenna illuminated by a laser operating in the TEM-00 mode. A simple polynomial equation is derived for matching the incident source distribution to a general antenna configuration for maximum on-axis gain. An interpretation of the resultant gain curves allows a number of auxiliary design curves to be drawn that display the losses in antenna gain due to pointing errors and the cone angle of the beam in the far field as a function of antenna aperture size and its central obscuration. The results are presented in a series of graphs that allow the rapid and accurate evaluation of the antenna gain which may then be substituted into the conventional range equation.
Klein, B. J.↗
Effects of mismatch on group delay of microwave transmission
Calculation method can be applied to transmission lines operating in TEM mode or to single-mode propagation in waveguides. Derived data are useful for estimating limits on variation of group delay with frequency or in determining how much discontinuity reduction is necessary to achieve given accuracy in predicting group delay.
Beatty, R. W.↗
Diode pumped Nd:YAG laser development
A low power Nd:YAG laser was constructed which employs GaAs injection lasers as a pump source. Power outputs of 125 mW TEM CW with the rod at 250 K and the pump at 180 K were achieved for 45 W input power to the pump source. Operation of the laser, with array and laser at a common heat sink temperature of 250 K, was inhibited by difficulties in constructing long-life GaAs LOC laser arrays. Tests verified pumping with output power of 20 to 30 mW with rod and pump at 250 K. Although life tests with single LOC GaAs diodes were somewhat encouraging (with single diodes operating as long as 9000 hours without degradation), failures of single diodes in arrays continue to occur, and 50 percent power is lost in a few hundred hours at 1 percent duty factor. Because of the large recent advances in the state of the art of CW room temperature AlGaAs diodes, their demonstrated lifetimes of greater than 5,000 hours, and their inherent advantages for this task, it is recommended that these sources be used for further CW YAG injection laser pumping work.
Reno, C. W.↗
Dual-polarized ring lasers
Simultaneous laser oscillation of four nondegenerate polarization and propagation direction eigenstates of a single TEM-00 mode was observed in a ring laser cavity. The observed polarization and frequency properties of the ring laser were analyzed in terms of the Jones matrix calculus.
Sanders, V. E.↗
The effect of minor additions of titanium on the fracture toughness of Fe-12Ni alloys at 77K
Titanium additions ranging from 0.18 to 0.99 atomic percent and heat treatments of 2 hours at 550, 685 and 820 C respectively followed by a water quench were considered. Cubic and rectangular shaped inclusions were noted in the SEM fractographs of the alloys with the Ti additions. A fine precipitate was observed by TEM for the Fe-12Ni-0.18Ti alloys heat treated at 550 C; this precipitate was not observed for the 685 and 820 C heat treatments of the same alloy. Auger mappings of the fracture surfaces indicated a weak to moderate association of the interstitials C, N and O with Ti, the degree of which depended on the particular interstitial and the heat treatment temperature.
Conrad, H.↗
Modification of the continuous flow diffusion chamber for use in zero-gravity
The design philosophy and performance characteristics of the continuous flow diffusion chamber developed for use in ground-based simulation of some of the experiments planned for the atmospheric cloud physics laboratory during the first Spacelab flight are discussed. Topics covered include principle of operation, thermal control, temperature measurement, tem-powered heat exchangers, wettable metal surfaces, sample injection system, and control electronics.
Keyser, G.↗
Infrared image construction with computer-generated reflection holograms
Computer-generated reflection holograms hold substantial promise as a means of carrying out complex machining, marking, scribing, welding, soldering, heat treating, and similar processing operations simultaneously and without moving the work piece or laser beam. In the study described, a photographically reduced transparency of a 64 x 64 element Lohmann hologram was used to make a mask which, in turn, was used (with conventional photoresist techniques) to produce a holographic reflector. Images from a commercial CO2 laser (150W TEM(00)) and the holographic reflector are illustrated and discussed.
Angus, J. C.↗
Pulsed-electron-beam annealing of ion-implantation damage
Short-duration high-intensity pulsed electron beams have been used to anneal ion-implantation damage in silicon and to electrically activate the dopant species. Lattice regrowth and dopant activation were determined using He(+)-4 backscattering, SEM, TEM, and device performance characteristics as diagnostic techniques. The annealing mechanism is believed to be liquid-phase epitaxial regrowth initiating from the substrate. The high-temperature transient pulse produced by the electron beam causes the dopant to diffuse rapidly in the region where the liquid state is achieved.
Greenwald, A. C.↗
The structure of small, vapor-deposited particles. II - Experimental study of particles with hexagonal profile
'Multiply-twinned' gold particles with hexagonal bright field TEM profile were determined to be icosahedra composed of 20 identical and twin-related tetrahedral building units that do not have an fcc structure. The crystal structure of these slightly deformed tetrahedra is rhombohedral. Experimental evidence supporting this particle model was obtained by selected-zone dark field and weak beam dark field electron microscopy. In conjunction with the results of part I, it has been concluded that multiply-twinned gold particles of pentagonal or hexagonal profile that are found during the early stages of the vapor deposition growth process on alkali halide surfaces do not have an fcc crystal structure, which is in obvious contrast to the structure of bulk gold.
Yacaman, M. J.↗