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M S Pindzola - One of the best experts on this subject based on the ideXlab platform.

  • Electron-Impact Ionization of the N atom
    Journal of Physics B, 2014
    Co-Authors: Sh. A. Abdel-naby, M S Pindzola, C P Ballance, A.j. Pearce, Stuart Loch
    Abstract:

    Electron-Impact Ionization cross sections for the ground and excited states of the N atom are calculated using the non-perturbative R-matrix with pseudo-states and time-dependent close-coupling (TDCC) methods, as well as the perturbative distorted-wave method. The TDCC and distorted-wave results for the () excited configurations are much larger than for the ground configuration. In all cases the TDCC results are substantially lower than the distorted-wave results. The Ionization cross section results will lead to a better understanding of moderately dense astrophysical and laboratory plasmas containing nitrogen.

  • Electron-Impact Ionization of C+ and C3+
    Journal of Physics: Conference Series, 2012
    Co-Authors: M S Pindzola, C P Ballance, S D Loch
    Abstract:

    Non-perturbative close-coupling and perturbative distorted-wave methods are used to calculate Electron-Impact Ionization cross sections for the excited states of C+ and C3+.

  • Electron-Impact Ionization of Al
    Journal of Physics B, 2012
    Co-Authors: Stuart Loch, C P Ballance, Di Wu, Sh. A. Abdel-naby, M S Pindzola
    Abstract:

    Perturbative distorted-wave and non-perturbative close-coupling methods are used to calculate Electron-Impact Ionization cross sections for the ground state of the neutral Al atom. Configuration-average distorted-wave calculations are made for both direct Ionization and excitation-autoIonization contributions. The total perturbative results are found to be almost a factor of 2 higher than experiment over a wide energy range. On the other hand, the R-matrix with pseudo-states results for total Ionization are found to be in good agreement with experiment. Comparison of time-dependent close-coupling calculations for the direct Ionization with the R-matrix with pseudo-state calculations for total Ionization reveals that both the direct Ionization and excitation-autoIonization contributions are strongly affected by correlation effects.

  • Electron-Impact Ionization of C2
    Journal of Physics B, 2010
    Co-Authors: M S Pindzola, C P Ballance, J. A. Ludlow, Stuart Loch, James Colgan
    Abstract:

    In support of tokamak edge plasma studies, we calculate the Electron-Impact Ionization cross section for the ground state of the diatomic carbon molecule. Bound orbitals for C2 and C+2 are calculated using a single-configuration self-consistent-field method based on a linear combination of Slater-type orbitals. Continuum distorted-wave orbitals are calculated using a two-dimensional lattice (r, θ), which is variable in the radial coordinate and constant in the angular coordinate. Using a perturbative configuration-average distorted-wave method, the first ab initio fully quantal Ionization cross sections for C2 at its equilibrium internuclear separation are presented.

  • Electron-Impact Ionization of ground and metastable neon
    Journal of Physics B, 2009
    Co-Authors: C P Ballance, M S Pindzola, J. A. Ludlow, Stuart Loch
    Abstract:

    Electron-Impact Ionization of neutral neon continues to be of interest both from a fundamental and an applied perspective. Non-perturbative calculations are required for the Electron-Impact Ionization of ground and excited states of neon. R-matrix with pseudostates (RMPS) calculations for the Electron-Impact Ionization of the 1s22s22p6 ground state of Ne at higher incident Electron energies are now made possible by the further partitioning of each individual LS partial wave across a greater number of processors. Furthermore, instead of a long sequence of parallel matrix diagonalizations, every partial wave diagonalization is now carried out concurrently. The ground-state cross section is found to be in excellent agreement with recent experimental measurements. The previous work of Ballance et al (2004 J. Phys. B: At. Mol. Opt. Phys. 37 4779), for the Ionization of the 1s22s22p53s excited state of Ne, has been extended to examine the Ionization of the 1s22s22p54s and 1s22s22p55s excited states. Very good agreement is found between R-matrix with pseudostates and time-dependent close-coupling calculations for the 1s22s22p54s excited state. The non-perturbative cross sections for low nl are used to scale semi-classical Impact parameter cross sections to high nl. Ionization cross sections for the ground and all excited states will enable the accurate determination of the generalized collisional-radiative Ionization rate coefficient for neutral Ne in finite plasmas.

M E Rudd - One of the best experts on this subject based on the ideXlab platform.

  • new model for Electron Impact Ionization cross sections of molecules
    Journal of Chemical Physics, 1996
    Co-Authors: W Hwang, M E Rudd
    Abstract:

    A theoretical model for Electron‐Impact Ionization cross sections, which has been developed primarily for atoms and atomic ions, is applied to neutral molecules. The new model combines the binary‐encounter theory and the Bethe theory for Electron‐Impact Ionization, and uses minimal theoretical data for the ground state of the target molecule, which are readily available from public‐domain molecular structure codes such as GAMESS. The theory is called the binary‐encounter Bethe (BEB) model, and does not, in principle, involve any adjustable parameters. Applications to 19 molecules, including H2, NO, CH2, C6H6, and SF6, are presented, demonstrating that the BEB model provides total Ionization cross sections by Electron Impact from threshold to several keV with an average accuracy of 15% or better at the cross section peak, except for SiF3. The BEB model can be applied to stable molecules as well as to transient radicals.

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

W Hwang - One of the best experts on this subject based on the ideXlab platform.

  • new model for Electron Impact Ionization cross sections of molecules
    Journal of Chemical Physics, 1996
    Co-Authors: W Hwang, M E Rudd
    Abstract:

    A theoretical model for Electron‐Impact Ionization cross sections, which has been developed primarily for atoms and atomic ions, is applied to neutral molecules. The new model combines the binary‐encounter theory and the Bethe theory for Electron‐Impact Ionization, and uses minimal theoretical data for the ground state of the target molecule, which are readily available from public‐domain molecular structure codes such as GAMESS. The theory is called the binary‐encounter Bethe (BEB) model, and does not, in principle, involve any adjustable parameters. Applications to 19 molecules, including H2, NO, CH2, C6H6, and SF6, are presented, demonstrating that the BEB model provides total Ionization cross sections by Electron Impact from threshold to several keV with an average accuracy of 15% or better at the cross section peak, except for SiF3. The BEB model can be applied to stable molecules as well as to transient radicals.

Hong Wang - One of the best experts on this subject based on the ideXlab platform.

  • Temperature dependence of the Electron Impact Ionization in InGaP-GaAs-InGaP DHBTs
    IEEE Transactions on Electron Devices, 2004
    Co-Authors: Hong Wang
    Abstract:

    Temperature dependence of Electron Impact Ionization in InGaP-GaAs-InGaP double heterojunction bipolar transistors (DHBTs) were comprehensively studied in the temperature range of 300 to 450 K. It has been found that, as the temperature increases, the Electron multiplication in the InGaP collector is found to be weakly reduced, which results in a relatively small negative temperature dependence of junction breakdown. The temperature dependence of Electron Impact Ionization at elevated temperatures for InGaP material is investigated based on the Electron multiplications measured from the InGaP collector region. An empirical expression is obtained to predict the Electron Ionization coefficients at elevated temperature up to 450 K in the electric field range of 380 to 650 kV/cm. As compared to InP and GaP binaries, the ternary InGaP shows a lower Electron Ionization coefficient and much weaker temperature dependence. We found that, introducing additional scattering mechanism such as alloy scattering would provide a better interpretation on the low Electron Impact Ionization and its weak temperature dependence observed in InGaP.