Performance of 3 m fiber optic light guides

We describe the performance of 3 m long fiber optic light guides that we have fabricated as part of a search for the rare decay μ⁺ → e⁺ + γ at LAMPF. The acceptance cone of the light guides is narrow, leading to substantial ( ≈ 80%) light loss entering th guides. But those photons that do fall within the acceptance cone are transmitted long distances without significant further loss. We discuss our fabrication techniques and the results of both bench tests and in-beam tests of complete assemblies.     

Solution of conjugate problem in successive intervals

The conjugate problem is solved for nonsteady heat transfer through a plane wall with convective heat transfer at the edges.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 33, No. 6, pp. 1031–1036, December, 1977.     

Solution of a two-dimensional conjugate problem of stabilized heat transfer in the laminar flow of a liquid in a channel

A two-dimensional problem of conjugate heat exchange is solved by the method of integral boundary-value equations. Heat exchange in a body with cylindrical channels is studied.Translated from Inzhererno-Fizicheskii Zhurnal, Vol. 44, No. 1, pp. 41–44, January, 1983.     

The difference method of solving the conjugate problem of heat exchange during gas flow in a thick-walled channel between communicating vessels

An algorithm is developed for the numerical solution of a nonlinear system of differential equations describing the processes of gasdynamics and heat exchange during the transfer of gas from vessel to vessel through a flat, annular, or cylindrical channel with walls of finite thickness.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 33, No. 6, pp. 1109–1116, December, 1977.     

Interconnect characteristics of fiber image guides

We investigated various factors that influence the transmission of high-density and high-bandwidth signals propagated through fiber image guides. The effects of signal power uniformity, optical cross talk, mode dispersion, and modal noise were considered. A model for power uniformity and optical cross talk is provided that we used to evaluate the channel density of several coupling modes. Also, modal noise was experimentally measured for several conditions of coupling to the fiber image guide. A commercially available fiber image guide was evaluated in the context of these performance considerations and was experimentally tested. The resultant minimum signal channel based on these criteria was found to consist of three fiber elements. The limit on transmission length that is due to modal dispersion was estimated at 1.65 m at 2.5-Gbits/s and at 42 cm at 10-Gbits/s data rates. Optical cross talk and modal noise were found to place a lower limit on the signal channel density. These characteristics compare favorably with electrical interconnect densities that are projected for tape automated bonding and flip-chip bonding techniques used at the chip-to-module and chip-to-board packaging levels.     

Transmission of light through right-angle corners in hollow light guides

Transmission of light through the corners in hollow light guides is compared for a new type of corner that is based on a laser-cut light-deflecting panel and for a flat, 45°, mirror-type corner. Corner efficiency is defined, and an experimental method for the measurement of the corner efficiency versus the angular width of the input light is described. Measured corner efficiencies were found to be nearly independent of the angular width of the incident light for metallic hollow light guides, with the average efficiency of the laser-cut-panel corner (65%) lower than that of the mirror corner (80%).     

Solution of the inverse problem on determining three fiber composite characteristics

A method is proposed to determine the characteristics of a bonded composite: the fiber and matrix heat conductivity coefficients and the heat transfer coefficient between them, from the solution of the inverse problem of heat conduction.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 58, No. 3, pp. 493–499, March, 1990.     

Microstructured light guides overcoming the two-dimensional concentration limit

Light guides are employed to homogenize an illumination distribution, to translate cross-sectional beam shapes, and to provide concentration. Microstructures enhance the performance of light guides based on the selective mixing of direction vector components in the two-dimensional phase space (etendue) that is perpendicular to the system's optical axis. For linear concentrators we find that the microstructured light guide beats the two-dimensional concentration limit and roughly allows for a three-dimensional concentration ratio. This result is verified in simulation and experiment.     

Solution methods for gas flow in ducts through the whole pressure regime

In vacuum technology it is frequently necessary to calculate gas flows over a wide range of pressures and flow conditions. Ideally, it is desirable to be able to conduct calculations for long and short ducts and for large and small pressure differences and flow rates. The basic requirement for a general purpose flow calculation method is a combined continuum/molecular model that provides a smooth transition between the flow regimes. Since gases are compressible a generally applicable model requires the application of thermodynamic flow relations.The thermodynamic flow equations are introduced and, in particular, a form applicable to laminar flow conditions together with equations that relate flow velocities to the applied boundary conditions (not generally covered in the fluid dynamics literature).In addition to circular cross-section ducts it is desirable to be able to include other common cross-section shapes so the equations discussed are generalised to include annular and rectangular cross-sections. Continuum flow formulas for these shapes are well known but there appear to be no published formulas for molecular flow in rectangular or annular cross-section ducts of arbitrary length. Empirical formulas which have been developed by the author for annular and rectangular ducts are presented.     

On the problem of rarefied gas flow past blunt axisymmetric bodies

Shock layer separation in flows of rarefied gas past axisymmetric models is determined by interferometric methods. The form of the density jump is established.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 15, No. 5, pp. 843–846, November, 1968.     

On a boundary layer problem related to the gas flow in shales

The development of gas deposits in shales has become a significant energy resource. Despite the already active exploitation of such deposits, a mathematical model for gas flow in shales does not exist. Such a model is crucial for optimizing the technology of gas recovery. In the present article, a boundary layer problem is formulated and investigated with respect to gas recovery from porous low-permeability inclusions in shales, which are the basic source of gas. Milton Van Dyke was a great master in the field of boundary layer problems. Dedicating this work to his memory, we want to express our belief that Van Dyke’s profound ideas and fundamental book Perturbation Methods in Fluid Mechanics (Parabolic Press, 1975) will live on—also in fields very far from the subjects for which they were originally invented.     

Solution of two conjugate equations

A solution to the conjugacy problem of various types of equation has been found by reduction to an integral equation; the problem arises in the study of heat-and masstransfer and in mechanical or electric phenomena in diverse media. Conditions are found which must be imposed on given functions for which the problem has a classical solution.     

Transmission of IR light by light guides made of silver halide solid solutions

The possibility of transferring IR emission by light guides made of silver halide solid solutions has been experimentally studied. The energy loss in transmission of the heat radiation through a light guide in various wavelength ranges of IR light was determined. The possibility of using IR light guides for transport of thermal energy and temperature measurements by IR thermography was considered.     

Inverse spectral problems used for the synthesis of diffusional light guides

The method of the inverse problem of scattering theory is used to analyze processes of radiation propagation and mass transfer in optical guiding systems.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 50, No. 2, pp. 316–324, February, 1986.