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Paul S. Erdman - One of the best experts on this subject based on the ideXlab platform.

  • High temperature spectroscopy of alkali Metal Vapors for solar to thermal energy conversion
    1994
    Co-Authors: Paul S. Erdman, William C. Stwalley
    Abstract:

    Abstract : Solar Plasma propulsion methods proposed by the Air Force have lead to the study of high temperature optical absorption of Metal Vapors. The Plasma Spectroscopy Cell in the Phillips Laboratory at Edwards AFB CA has been used to obtain an abundance of absorption spectra at temperatures approaching 2000 K and pressures of one atmosphere for lithium and sodium Metal Vapors. Tentative assignments of molecular transitions are improved upon by use of modern computational techniques for generating intensities of molecular transitions which possibly have been observed. Identification of contributing molecular transitions to overall absorption of radiant energy assists the efforts to develop propulsion methods which rely on the direct absorption of solar energy. jg

  • Optical spectroscopy of Metal Vapors
    Bulletin of the American Physical Society, 1993
    Co-Authors: J.d. Mills, P.w. Langhoff, Paul S. Erdman
    Abstract:

    Absorbance spectra are reported for selected diatomic combinations (Li{sub 2}, Na{sub 2}, LiAl, ...) of atomic Metal Vapors (Li, Na, Al) in support of transmission measurements made in a high-temperature (T {approx} 1,600 to 1,800{degrees}K) flow apparatus. The computational model adopted for interpretation of measured data incorporates Voigt lineshapes and rovibronic positions and transition strengths derived from previous spectral measurements or from ab initio potential curves and transition dipole moment functions. Particular attention is addressed to comparison of the calculated high-resolution spectra obtained from state-specific transition intensities with corresponding Franck-Condon approximations and with measurements in Li/Li{sub 2} and Na/Na{sub 2} Vapors. Comments are provided on diagnostic characterization of spatial anisotropies in the flow apparatus employed in these cases, and on detection of previously unobserved Metal diatomics.

  • SPECTROSCOPY OF Metal Vapors
    1993
    Co-Authors: J.d. Mills, Paul S. Erdman, C. W. Larson, Mario E. Fajardo, William C. Stwalley
    Abstract:

    Author Institution: Department of Chemistry, Indiana University Bloomington; Propulsion Division, Phillips Laboratory; Department of Physics, University of Iowa

Fatemeh Niroomand-hosseini - One of the best experts on this subject based on the ideXlab platform.

  • Hard-wall potential function for transport properties of alkali Metal Vapors.
    The Journal of chemical physics, 2007
    Co-Authors: Mohammad Hadi Ghatee, Fatemeh Niroomand-hosseini
    Abstract:

    This study demonstrates that the transport properties of alkali Metals are determined principally by the repulsive wall of the pair interaction potential function. The (hard-wall) Lennard-Jones (LJ) (15-6) effective pair potential function is used to calculate the transport collision integrals. Accordingly, reduced collision integrals of K, Rb, and Cs Metal Vapors are obtained from the Chapman-Enskog solution of the Boltzmann equation. The law of corresponding states based on the experimental transport reduced collision integral is used to verify the validity of a LJ(15-6) hybrid potential in describing the transport properties. LJ(8.5-4) potential function and a simple thermodynamic argument with the input PVT data of liquid Metals provide the required molecular potential parameters. Values of the predicted viscosity of monatomic alkali Metal vapor are in agreement with typical experimental data with average absolute deviations of 2.97% for K in the range of 700–1500K, 1.69% for Rb, and 1.75% for Cs in t...

Mohammad Hadi Ghatee - One of the best experts on this subject based on the ideXlab platform.

  • Hard-wall potential function for transport properties of alkali Metal Vapors.
    The Journal of chemical physics, 2007
    Co-Authors: Mohammad Hadi Ghatee, Fatemeh Niroomand-hosseini
    Abstract:

    This study demonstrates that the transport properties of alkali Metals are determined principally by the repulsive wall of the pair interaction potential function. The (hard-wall) Lennard-Jones (LJ) (15-6) effective pair potential function is used to calculate the transport collision integrals. Accordingly, reduced collision integrals of K, Rb, and Cs Metal Vapors are obtained from the Chapman-Enskog solution of the Boltzmann equation. The law of corresponding states based on the experimental transport reduced collision integral is used to verify the validity of a LJ(15-6) hybrid potential in describing the transport properties. LJ(8.5-4) potential function and a simple thermodynamic argument with the input PVT data of liquid Metals provide the required molecular potential parameters. Values of the predicted viscosity of monatomic alkali Metal vapor are in agreement with typical experimental data with average absolute deviations of 2.97% for K in the range of 700–1500K, 1.69% for Rb, and 1.75% for Cs in t...

A. S. Shumikhin - One of the best experts on this subject based on the ideXlab platform.

  • Thermodynamics and transport properties of the supercritical fluid of Metals
    High Temperatures-High Pressures, 2020
    Co-Authors: A. L. Khomkin, A. S. Shumikhin
    Abstract:

    The proposed model allows to calculate the composition, thermodynamic and transport properties of the supercritical Metal Vapors within unified approach. The model includes atoms, immersed in jellium, and thermally ionized electrons and ions. The jellium is the part of the bound states electron density. The density of electron jellium increases with the compression of atomic gas and does not depend on temperature directly. At compression, the electrical conductivity passes through the minimum from the conductivity of thermal electrons to the conductivity of electrons of jellium accordingly. Calculations of the equation of state and the electrical conductivity of supercritical Metal Vapors agree well with physical and numerical experimental data.

  • Conductivity of Metal Vapors at the critical point
    Journal of Experimental and Theoretical Physics, 2016
    Co-Authors: A. L. Khomkin, A. S. Shumikhin
    Abstract:

    The conductivity of Metal Vapors at the critical point and near it has been considered. The liquid-Metal conductivity originates in this region. The thermodynamic parameters of the critical point, the density of conduction electrons, and the conductivities of various Metal Vapors have been calculated within the unified approach. It has been proposed to consider the conductivity at the critical point—critical conductivity—as the fourth critical parameter in addition to the density, temperature, and pressure.

  • Critical points of Metal Vapors
    Journal of Experimental and Theoretical Physics, 2015
    Co-Authors: A. L. Khomkin, A. S. Shumikhin
    Abstract:

    A new method is proposed for calculating the parameters of critical points and binodals for the vapor–liquid (insulator–Metal) phase transition in Vapors of Metals with multielectron valence shells. The method is based on a model developed earlier for the Vapors of alkali Metals, atomic hydrogen, and exciton gas, proceeding from the assumption that the cohesion determining the basic characteristics of Metals under normal conditions is also responsible for their properties in the vicinity of the critical point. It is proposed to calculate the cohesion of multielectron atoms using well-known scaling relations for the binding energy, which are constructed for most Metals in the periodic table by processing the results of many numerical calculations. The adopted model allows the parameters of critical points and binodals for the vapor–liquid phase transition in Metal Vapors to be calculated using published data on the properties of Metals under normal conditions. The parameters of critical points have been calculated for a large number of Metals and show satisfactory agreement with experimental data for alkali Metals and with available estimates for all other Metals. Binodals of Metals have been calculated for the first time.

  • Vapor-liquid (insulator-Metal) phase transition in alkali Metal Vapors
    Journal of Experimental and Theoretical Physics, 2014
    Co-Authors: A. L. Khomkin, A. S. Shumikhin
    Abstract:

    A simple physical model is proposed that describes a vapor-liquid phase transition in alkali Metal Vapors. The model is based on an assumption made on the character of binding between atoms in the gas phase near the critical point. This is the collective quantum cohesive energy, well-known in the theory of liquid alkali Metals, which arises due to the appearance of conduction electrons and is extended to the gas region near the critical point. The parameters of the critical points of the transition and of the binodal are determined on the basis of the model calculation of the binding energy for all alkali Metals. Combined, these parameters well agree with experimental results and the predictions made by other authors. The minimum Metallic conductivity is evaluated. Its behavior allows one to conclude that vapor-liquid and insulator-Metal transitions in alkali Metal Vapors coincide. This fact sheds light on the Zel’dovich-Landau problem as applied to alkali Metal Vapors.

Heinz M. Kuss - One of the best experts on this subject based on the ideXlab platform.

  • Separation of Metal Vapors for atomic spectroscopy techniques by high-temperature chromatography on graphite
    Spectrochimica Acta Part B: Atomic Spectroscopy, 1997
    Co-Authors: Ilia L. Grinshteyn, Vladimir A. Kopeikin, Lubov A Vasilieva, S.n. Golubev, Heinz M. Kuss
    Abstract:

    Abstract The separation of different Metal Vapors when flowing through the porous graphite partition placed in electrothermal atomizer has been studied. At high temperatures the porous graphite partition works as a chromatographic column. The separation efficiency depends on the temperature of the furnace column and on the carrier gas flow through the partition. The possibility of the total separation of the elements Ag, Pb, Zn and Cd from the elements Mn, Cu, Fe and Ni has been demonstrated.