The line source technique for determination of thermal conductivity has been modified to allow measurement to higher temperatures than previously attained. This required the addition of a high-temperature tube furnace to the standard experimental equipment. The modified device was used to measure the temperature-dependent thermal conductivities of a glassand talc-filled phenol-formaldehyde(pheno1ic) resin and a glass-and fiberglass-filled acrylonitrile-butadiene (AB) copolymer. Thermal conductivities of the virgin material were measured from room temperature to the onset of thermal decomposition. The char material thermal conductivities were measured from room temperature to approximately 900°C. A least-squares fit of the data yielded a linear-curve fit for the virgin material and a third-order fit for the char material.

The line source technique for determination of thermal conductivity has been modified to allow measurement to higher temperatures than previously attained. This required the addition of a high‐temperature tube furnace to the standard experimental equipment. The modified device was used to measure the temperature‐dependent thermal conductivities of a glass‐ and talc‐filled phenol‐formaldehyde(phenolic) resin and a glass‐ and fiberglass‐filled acrylonitrile‐butadiene (AB) copolymer. Thermal conductivities of the virgin material were measured from room temperature to the onset of thermal decomposition. The char material thermal conductivities were measured from room temperature to approximately 900°C. A least‐squares fit of the data yielded a linear‐curve fit for the virgin material and a third‐order fit for the char material.

The work discussed in the present paper was undertaken in response to difficulties experienced with numerical integration approaches. The technique involves the modeling of the medium as a set of horizontal strata in which the ambient gas parameters are ‘nearly’ constant, i.e., slowly varying. A perturbation theory allows us to take into account the slow vertical variation in a purely analytical way that is based on a knowledge of the system‐equation solutions for a homogeneous medium. The computer is used to find eigenvalues of the system matrix and to provide the numerical coefficients for the solution matrix, which is expressed analytically as a function of z, the vertical distance coordinate. Illustrative numerical results are presented that show eigenvalues (corresponding to modes of propagation) and certain elements of the solution matrix for a typical ionospheric parameter regime.

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Wave propagation in a one-fluid compressible, inhomogeneous, and lossy plasma is studied. Coupling between the electroacoustic and electromagnetic waves is investigated analytically. The inhomogeneity of the medium is due to the variation of the electron density, collision frequency, and temperature along the vertical direction only (z direction). An E polarized electromagnetic wave is assumed to be incident from a vacuum to a slowly varying, inhomogeneous, compressible, and lossy plasma occupying the half space defined by z > 0. Among the various possible boundary conditions at z --0 that involve the electroacoustic fields, the vanishing of the pressure at z = 0 is chosen so that the numerical computation becomes relatively simple. The profiles of the electron density, the collision frequency, and the temperature are chosen so that they are consistent with this type of boundary condition. The numerical results presented here show the dependence of the coupling characteristics (i.e., the transfer of energy from em waves to p waves) on the various plasma parameters and other parameters. Conditions for the validity of the perturbation method are examined and are proved to be satisfied for the problem.In the model discussed in that work, the ionosphere is described by linearized equations that govern the behavior of electron-ion neutral gas that is vertically nonuniform in the static parameters (e.g., pressures, densities, collision frequencies); the model includes the effects of the earth's magnetic field and gravity, viscosity, and thermal conductivity.Wave propagation in fully and partially ionized gas, with and without static magnetic field, has been studied by several authors [e.g., Tanenbaum and Mintzer, 1962; Wait, 1963]. However, these authors have usually treated the propagation of waves in linearized spatially homogeneous media or media with simplified (e.g., exponential) height variation of parameters. Some work has also been done to investigate atmospheric acoustic gravity waves [Pitte-way and Hines, 1963]. The major difference between the work of Raemer [1966a, b] and that of Raemer and Verma [1966, 1970] is that realistic static parameter profiles for the atmosphere (three-or more-component plasma) are used to study a very general model. The interacting mixture of electrons, ions, and neutral particles can be described in a mathematical model that consists of the Maxwell's equations, hydrodynamic equations, generalized Ohm's law, and the adiabatic-state equations. The resulting equations are first-order linear differential equations with variable coefficients. A direct analytical closed-form solution suitable for obtaining numerical values of the dependent variables is extremely difficult if not impossible to obtain. Even if the spatial inhomogeneity is assumed only in one direction (say the vertical direction (along the z axis)) and if suitable transformations are introduced in the x and y directions to reduce the system to one-dimensional differential equations involving z only, the solution of the g...