Equation of state,composition, and conductivity of dense metal-vapor plasma

The caloric and thermal equations of state, composition, and conductivity of dense vapor plasma of different metals (Cu, Ag, Au, Ti, Ni, and B) have been calculated for the temperature range of 10000–50000 K and for pressures up to 20000 atm. An ion-molecular chemical model of a nonideal gas-plasma mixture, which was previously proposed for an aluminum vapor plasma, has been used in the calculations. Results obtained for the equation of state and conductivity (resistance) of metal vapor in the range of applicability of the model are in fairly good agreement with the experimental data. A comparison of the calculation and experimental results for different metals suggests that the model proposed is universal for metal-vapor plasmas.     

Mechanical Properties of Simple s-p Metals, and Defect Energies from Electron Theory and from Interatomic Force Laws

The cleavage force F(z) needed to separate parallel atomic planes by a distance z is first discussed for simple s-p metals using density functional theory.For the s-p nearly free-electron metals the linearized Thomas-Fermi equation is solved self-consistently in the cases of (a) semi-infinite planes of jellium (i.e. smeared uniform positive ions) and (b) a semi-infinite cylinder of finite radius, cleaved by a plane perpendicular to its axis. In (a), the elastic region has the form F(z)=Az ∝ Zrs-11/2, where rs is the mean interelectronic distance in the jellium model. Size effects are then considered, with possible relevance to atomic force microscopy.Defect energies are treated, using both electron theory and pair force laws.     

Application du modèle théorique à l'étude des pertes d'énergie caractéristiques des électrons transmis et rétrodiffusés dans le cas de l'aluminium

This paper deals with a theoretical model concerning transmission and backscattering of electrons by thin self-supported aluminium targets.This model is based on the Boltzmann equation, and our studies are limited to low energy losses; we show the existence of plasmon peaks in the energy distributions of electrons.The effects of physical parameters appearing during interactions with the jellium are analysed, and the sensitivity of our model is checked.     

Thermal properties across threshold compositions in Ge-As-Se glasses

The Ge-As-Se chalcogenide glasses is an interesting system to test the validity of different constraint models proposed for these materials, in view of the fact that this system has a wide glass forming range which makes it possible to measure composition dependent properties over ranges covering most predicted thresholds. We have measured the thermal parameters—thermal diffusivity, thermal effusivity, thermal conductivity and heat capacity—of Ge-As-Se glasses covering composition range in which thresholds in physical properties have been predicted for covalent glasses employing a modified photopyroelectric technique. Our results show that this system exhibits a minimum in heat capacity at an average coordination number Z = 2.4 corresponding to a 3-D network as per the Phillips-Thorpe model, whereas thermal conductivity exhibits a threshold maximum at Z = 2.67 which is in agreement with the Tanaka model.     

Wide-range equations of state of granite and water with allowance for evaporation, dissociation, and ionization

Semiempirical wide-range equations of state of granite and water based on resolution of the pressure and energy into a cold component and thermal electronic and nuclear components are presented. The thermal electronic component is calculated using the Thomas-Fermi model, which makes it possible to describe both thermal ionization and ionization by pressure. Evaporation and dissociation are allowed for by introducing the corresponding terms into the free energy. The condensed state is described within the framework of the Debye approximation. The cold isotherm is constructed with allowance for available experimental data.     

Analytical calculation of distributions of the electron density and the concentration of impurity ions in a thermal dusty plasma using the jellium model for condensed particles

Self-consistent spatial distributions of the electron density in the entire volume of condensed-matter particles and the surrounding plasma, as well as distributions of the concentration of ions of easily ionized impurity atoms, are obtained using the jellium model to describe particles. It is established that electron emission from condensed particles in a thermal dusty plasma containing an impurity of an easily ionized element may weaken with an increase in temperature. The electron emission from particles is shown to increase with a decrease in their radius at a constant temperature. A plasma region with violated ionization equilibrium is found to form near the surface of condensed particles.     

Criteria of the thermal state of a hot cathode

Criteria characterizing the contributions of the main energy sources and sinks to the complex process of heat exchange in thermionic rod cathodes of low-temperature plasma generators are determined within the framework of a quasi-one-dimensional model. Using relations between these criteria, it is possible to evaluate various thermal regimes of operation of long high-current cathodes. A method for the optimization of the thermal state of such electrodes is developed. The results of calculations according to the proposed scheme agree with experimental data.     

用状态方程计算多元混合工质的热导率

利用ＰＲ状态方程结合修正的Ｅｎｓｋｏｇ理论计算了氮烃类多元混合工持的热导率。在压力为０．０７２－５．７１５ＭＰａ，温度为１２２．１９０－３３５．５Ｋ范围内，总绝对平均偏差为４．９８％《     

Sensitivity Tunable Inductive Fluid Conductivity Sensor Based on RF Phase Detection

New results are presented for a sensitivity-tunable, inductive fluid conductivity sensor based on RF phase detection. An electronically controlled RF phase shifter allows the sensor to function in a wide range of conductivities from 2-70 mS/cm and helps tune the sensitivity of the response in a selected conductivity range. The noncontact nature of the sensor makes it suitable for corrosive fluids. Furthermore, the small size of the sensing element (1 inch. Sq X 6 mm thick) makes it suitable for compact in-line and hand held monitoring systems.     

A New Model for the Thermal Conductivity of Molten Salts

A new model based on rough hard-sphere theory is proposed for the thermal conductivity of molten salts. The model incorporates a smooth hard-sphere contribution using the properties of argon, as well as characteristic parameters based on the melting point of the molten salt. It is demonstrated that it is possible to correlate the thermal conductivity of monovalent and multivalent molten salts within experimental error using this approach. Furthermore, in salts with a common anion, the single adjustable parameter in the model exhibits regular behavior with the molecular weight of the salt. It is also shown that the thermal conductivity of several molten-salt mixtures can be predicted without any mixture parameters.     

Prediction of transport properties of dense gases and liquids by the Peng-Robinson (PR) equation of state

An attempt is made in this work to combine the Enskog theory of transport properties with the simple cubic Peng-Robinson (PR) equation of state. The PR equation of state provides the density dependence of the equilibrium radial distribution function. A slight empirical modification of the Enskog equation is proposed to improve the accuracy of correlation of thermal conductivity and viscosity coefficient for dense gases and liquids. Extensive comparisons with experimental data of pure fluids are made for a wide range of fluid states with temperatures from 90 to 500 K and pressures from 1 to 740 atm. The total average absolute deviations are 2.67% and 2.02% for viscosity and thermal conductivity predictions, respectively. The proposed procedure for predicting viscosity and thermal conductivity is simple and straightforward. It requires only critical parameters and acentric factors for the fluids.Paper presented at the Tenth Symposium on Thermophysical Properties, June 20–23, 1988, Gaithersburg, Maryland, U.S.A.     

Selecting Cost-Optimal Main-Effect Fractions of 3' Factorials

The process of designing orthogonal fractions of three level factorial experiments which will estimate the main effects is reviewed. Under an assumption of heterogeneous costs of observations, a cost model is proposed which allows the engineer to determine experimental costs directly from confounding scheme decisions without being required to develop the complete fraction first. This makes it possible to explore for the minimum cost fraction more efficiently. An example application to designing fractional experiments for calibrating state highway skid measurement equipment is given.     

Thermomechanical Models of Irreversible Finite Deformation of Anisotropic Solids

The proposed models for irreversible finite deformation of initially anisotropic solids are based on the hypothesis of the parameters of state, for which the authors have chosen a universal parameter (temperature) and a strain component, which is analogous to volume strains in an isotropic body and represents thermal strains of an unconstrained (stress-free) anisotropic solid. The application of this hypothesis allows the strain tensor to be resolved into a reversible and irreversible components. For irreversible processes of finite deformation of hardenable materials, the authors have proposed a deformation-type model, which makes it possible to describe a change in the type of anisotropy of initially anisotropic materials in the course of deformation. For the flow-theory-type model, the limiting state function, as given in the space of irreversible strains, allows for the experimentally observed plastic flow of anisotropic crystals under the action of hydrostatic pressure only.     

Viscosity and Thermal Conductivity Equations for Nitrogen, Oxygen, Argon, and Air

New formulations for the viscosity and thermal conductivity for nitrogen, oxygen, argon, and air are given. Air is treated as a pseudo-pure fluid using an approach adopted from previous research on the equation of state for air. The equations are valid over all liquid and vapor states, and a simplified cross-over equation was used to model the behavior of the critical enhancement for thermal conductivity. The extrapolation behavior of the equations for nitrogen and argon well below their triple points was monitored so that both could be used as reference equations for extended corresponding states applications. The uncertainties of calculated values from the equations are generally within 2% for nitrogen and argon and within 5% for oxygen and air, except in the critical region where the uncertainties are higher. Comparisons with the available experimental data are given.     

The coaxial dielectric source of a high-purity ablation plasma with transverse outflow of a plasma jet

The developed coaxial dielectric source of a high-purity ablation (erosion) plasma at a low pressure has been studied experimentally. The use of a central dielectric rod makes it possible to increase the ablation surface area and to reduce the relative amount of impurities of the material of the electrodes. In the first approximation, a physical picture of the interaction of the magnetic field of the discharge current with the plasma jet flowing perpendicularly to the discharge channel has been proposed in terms of the reconnection of magnetic field lines.     

On the fluid thermal activity coefficient using water as an example

In conformity with the experimental results on the density, heat conductivity, specific heat, and viscosity of water, it is established that 1) the fluid thermal activity coefficient can be expressed in a form analogous to the equation of state, and 2) a linear dependence exists between the fluid thermal activity and heat conductivity coefficients as well as the viscosity.

     

Method for Solving the Problem of Monitoring the Technical State of Flying Vehicles Using a Fuzzy Measure

A method is proposed for the automated monitoring of the technical state of on-board systems of flying vehicles which makes it possible to estimate the reliability of monitoring using a fuzzy measure. An example of its implementation is given.     

MPCVD合成P型金刚石薄膜的电导——温度机理

研究了温度对Ｐ型金 石薄膜电导性能的影响，采用微波等离子体化学气相沉积（ＭＰＣＶＤ）的方法在Ｓｉ３Ｎ４基片上制作了掺硼金刚石薄膜，测量了不同掺硼浓度的电导温度特性关系，提出了一种简化的能带模型，解释了电导机理，基于能带模型计算出的电导－－温度关系结果与试验结果相符合。     

Effect of powder structure on microstructure and electrical properties of plasma-sprayed 4.5 mol% YSZ coating

Electrolyte coatings by atmospheric plasma spraying were prepared by 4.5 mol% ytrria-stabilized zirconia (YSZ) powders manufactured by agglomerate-sintered (A-S) and fusing-crashed (F-C) processes. Microstructure of the powders and the coatings were characterized using scanning electron microscopy. The electrical conductivity of the coatings was investigated using both impedance spectroscopy and DC methods. The results showed that the electrical conductivity of coating prepared with A-S powder was lower than that with F-C powder. It was found from the impedance analysis that both the grain and grain boundary resistances were large in the coating formed by A-S powder. This fact resulted from deposition of partially melting of spray particles. A model was proposed to explain the effect of powder structure and melting state on the coating microstructure and properties.