Abstract
Novel phenomena and methods related to dielectronic capture and dielectronic recombination are studied for non-local thermodynamic equilibrium (LTE) plasmas and for applications to non-LTE ionization balance. It is demonstrated that multichannel autoionization and radiative decay strongly suppress higher-order contributions to the total dielectronic recombination rates, which are overestimated by standard approaches by orders of magnitude. Excited-state coupling of dielectronic capture is shown to be much more important than ground-state contributions, and electron collisional excitation is also identified as a mechanism driving effective dielectronic recombination. A theoretical description of the effect of angular-momentum-changing collisions on dielectronic recombination is developed from an atomic kinetic point of view and is visualized with a simple analytical model. The perturbation of the autoionizing states due to electric fields is discussed with respect to ionization potential depression and perturbation of symmetry properties of autoionization matrix elements. The first steps in the development of statistical methods are presented and are realized in the framework of a local plasma frequency approach. Finally, the impact of collisional–radiative processes and atomic population kinetics on dielectronic recombination is critically discussed, and simple analytical formulas are presented.
Highlights
Atomic populations are of fundamental importance in a variety of areas in both pure and applied science
Novel phenomena and methods related to dielectronic capture and dielectronic recombination are studied for non-local thermodynamic equilibrium (LTE) plasmas and for applications to non-LTE ionization balance
Excited-state coupling of dielectronic capture is shown to be much more important than ground-state contributions, and electron collisional excitation is identified as a mechanism driving effective dielectronic recombination
Summary
Atomic populations are of fundamental importance in a variety of areas in both pure and applied science. Several charge states usually exist simultaneously, and the total radiation emission arises from excited states of different ionic charges This indicates that are the populations of excited states and their excitation mechanisms relevant but so too is the ionization balance. An important part of the overall DR processes is described well by a quasiclassical approach This opens up new ways to treat important phenomena occurring in plasmas other than purely quantum mechanical atomic structure calculations (e.g., the multiconfiguration Dirac–Fock method). (ii) by radiative decay of the ion core electron, resulting in its return to the initial state after the emission of a photon of energy Zω ≈ Zωcore ΔE, whereas the captured electron remains bound to the ion [compare with the relation (1.3)]. In convenient units (with ΓZjk,Z+1 in s−1, and F(E), EDkjC, and Te in eV), 2.9360 3 10−40ΓZjk,Z+1ggZkZj+1ΓZjk,Z+1F(EEDkDkjjCC) (cm s)
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