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420 results on '"Janev, R. K."'

1. Resonances in nonrelativistic free-free Gaunt factors with screened Coulomb interaction

Author

Wu, Ju Yan, Wu, Yong, Qi, Yue Ying, Wang, Jian Guo, Janev, R. K., and Zhang, Song Bin

Subjects
Physics - Atomic Physics, Physics - Plasma Physics
Abstract

The effect of Coulomb interaction screening on non-relativistic free-free absorption is investigated by integrating the numerical continuum wave functions. The screened potential is taken to be in Debye-H\H{u}ckel (Yukawa) form with a screening length D. It is found that the values of the free-free Gaunt factors for different Debye screening lengths D for a given initial electron energy \eps_i and absorbing photon energy \omega, generally lie between those of the pure Coulomb field and field-free case. However, for initial electron energies below 0.1 Ry and fixed photon energy, the Gaunt factors show dramatic enhancements (broad and narrow resonances) in the vicinities of the critical screening lengths, Dnl, at which the energies of nl bound states in the potential merge into the continuum. These enhancements of the Gaunt factors can be significantly higher than their values in the unscreened (Coulomb) case over a broad range of \eps_i. The observed broad and narrow resonances in the Gaunt factors are related to the temporary formation of weakly bound (virtual) and resonant (quasi-bound) states of the low-energy initial electron on the Debye-H\H{u}ckel potential when the screening length is in the vicinity of Dnl., Comment: 11 pages, 5 figures, Physical Review A (accepted)

Published
2018
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2. A review of quantum collision dynamics in Debye plasmas

Author

Janev, R. K., Zhang, Song Bin, and Wang, Jian Guo

Subjects
Physics - Atomic Physics
Abstract

Hot, dense plasmas exhibit screened Coulomb interactions, resulting from the collective effects of correlated many-particle interactions. In the lowest particle correlation order (pair-wise correlations), the interaction between charged plasma particles reduces to the Debye-H\"uckel (Yukawa-type) potential, characterized by the Debye screening length D. Due to the importance of Coulomb interaction screening in dense laboratory and astrophysical plasmas, hundreds of theoretical investigations have been carried out in the past few decades on the plasma screening effects on the electronic structure of atoms and their collision processes employing the Debye-H\"uckel screening model. The present article aims at providing a comprehensive review of the recent studies in atomic physics in Debye plasmas. Specifically, the work on atomic electronic structure, photon excitation and ionization, electron/positron impact excitation and ionization, and excitation, ionization and charge transfer of ion-atom/ion collisions will be reviewed., Comment: 9 figures

Published
2016
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3. Electron-impact dissociation cross sections of vibrationally excited He2+ molecular ion

Author

Celiberto, R., Baluja, K. L., Janev, R. K., and Laporta, V.

Subjects
Physics - Plasma Physics, Physics - Atomic Physics
Abstract

Electron-impact cross sections for the dissociation process of vibrationally excited He2+ molecular ion, as a function of the incident electron energy are calculated for the dissociative transition X2\Sigma+u \to A2\Sigma+g by using the R-matrix method in the adiabatic-nuclei approximation. The potential energy curves for the involved electronic states and target properties, also calculated with the R-matrix method, were found to be in good agreement with the results reported in literature.

Published
2015

10. Electron-impact state-to-state cross sections and rate coefficients for X(v)->A(v') excitation of LiH molecule

Author

Celiberto, R., Janev, R. K., and Laricchiuta, A.

Subjects
Electron-molecule collisions, vibrationally resolved cross sections and rates, electron-molecule cross sections, nuclear fusion, excited states
Abstract

Electron-impact cross sections for the v->V'transitions between the vibrational levels of X ? and A ? electronic states of the LiH molecule, are calculated from threshold to 1000 eV by using the threshold-modified Massey-Mott approximation. The rate coefficients for the same transitions are also calculated in the range 0.1-1000 eV. Scaling relationships for both the v - v? cross section and v - v? rate coefficients are derived, allowing us to represent the calculated quantities in a compact analytic form.

Published
2020

19. Electron-impact state-to-state cross sections and rate coefficients for excitation of LiH molecule.

Author

Celiberto, R, Janev, R K, and Laricchiuta, A

Subjects
*ELECTRON impact ionization, *MOLECULES, *RATES
Abstract

Electron-impact cross sections for the transitions between the vibrational levels of X1Σ+ and A1Σ+ electronic states of the LiH molecule, are calculated from threshold to 1000 eV by using the threshold-modified Massey–Mott approximation. The rate coefficients for the same transitions are also calculated in the range 0.1–1000 eV. Scaling relationships for both the v − v′ cross section and v − v′ rate coefficients are derived, allowing us to represent the calculated quantities in a compact analytic form. [ABSTRACT FROM AUTHOR]

Published
2020
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36. Atomic and molecular data for spacecraft re-entry plasmas

Author

Celiberto, R, primary, Armenise, I, additional, Cacciatore, M, additional, Capitelli, M, additional, Esposito, F, additional, Gamallo, P, additional, Janev, R K, additional, Laganà, A, additional, Laporta, V, additional, Laricchiuta, A, additional, Lombardi, A, additional, Rutigliano, M, additional, Sayós, R, additional, Tennyson, J, additional, and Wadehra, J M, additional

Published
2016
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41. Photoionization of C5+ ion in warm dense plasmas.

Author

Zhao, G. P., Xie, L. Y., Liu, L., Wang, J. G., and Janev, R. K.

Subjects
DENSE plasmas, PHOTOIONIZATION, PLASMA density, NUCLEAR cross sections, KINETIC energy, DEGENERATE perturbation theory
Abstract

The photoionization process of the C5+ ion in warm, dense plasmas is studied using the relativistic approximation. Cross section calculations are performed for plasma density and temperature ranges of ne ∼ 1023–1026 cm−3 and Te = 150–300 eV, respectively. The used static screened potential includes the effects of plasma degeneracy, finite-temperature gradient corrections to the kinetic energy, and quantum exchange-correlation. The dependencies of the photoionization cross section on plasma density (for fixed temperature) and temperature (for fixed density) are investigated. [ABSTRACT FROM AUTHOR]

Published
2018
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48. Electron capture and excitation processes in collisions of H+ with H in finite-temperature quantum plasmas.

Author

Zhao, G. P., Liu, L., Wang, J. G., and Janev, R. K.

Subjects
ELECTRON capture, QUANTUM plasmas, ATOMIC orbitals, PLASMA density, PLASMA gases
Abstract

Electron capture and excitation processes in H+-H collisions imbedded in warm dense quantum plasmas are studied by the two-center atomic orbital close-coupling (TC-AOCC) method in the energy range 1-200 keV. The screened potential which is used to describe the interaction between charged particles incorporates the quantum electron degeneracy, exchange-correlation and finite-temperature gradient correlation effects. The total and state-selective electron capture and excitation cross-sections for this collision system with this potential are calculated in a wide range of plasma densities and temperatures. It is demonstrated that the screening of Coulomb interactions affects the collision dynamics and the magnitude and energy behavior of the excitation and electron capture cross-sections. The results at very low and high temperatures are also compared with those obtained for zero-temperature quantum plasmas and Debye plasmas, respectively. [ABSTRACT FROM AUTHOR]

Published
2017
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49. Collision processes of C2,3Hy and C2,3H y hydrocarbons

Author

Janev, R. K. and Reiter, D.

Subjects
ddc:530
Abstract

Cross sections and rate coefficients are provided for inelastic collision processes of electrons and protons with CxHy and CxHy+ (x=2,3; 1less than or equal toyless than or equal to2x+2) hydrocarbon species in a wide range of collision energies and plasma (gas) temperatures. The considered processes include electron-impact ionization and dissociation of CxHy, dissociative excitation, ionization and recombination of CxHy+ with electrons, and both charge transfer and atom exchange in proton channels are considered separately. The presented cross sections are based upon a critical assessment of available experimental data and upon an extensive use of a number of semi-empirical, physically well grounded cross section scaling relationships. Information is also provided for the energetics of each individual reaction channel. The cross sections and rate coefficients are presented in compact analytic forms. (C) 2004 American Institute of Physics.

Published
2004

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