Generalized energy approach for calculating electron collision cross‐sections for multicharged ions in a plasma: Debye shielding model

Abstract

A uniform quantum energy approach for studying spectra of the multicharged ions in a plasmas and the electron-ion collision cross sections is presented. The approach is based on formally exact QED theory by using the relativistic Dirac Hamiltonian for electron-nuclear and electron-electron potentials, the gauge invariant scheme of generation for the optimal one-quasiparticle representation and the Debye shielding model. The measured and calculated electron-collisional excitation cross sections for Ne-like barium ion for different values of the incident electron energy are presented and analyzed.

Spectroscopy of Rydberg atoms in a Black-body radiation field: Relativistic theory of excitation and ionization

“…We apply a generalized energy approach [11][12][13][14][15] and relativistic perturbation theory with the MP zeroth approximation [16][17][18][19][20] to computing the Rydberg atoms ionization parameters. In relativistic theory radiation decay probability (ionization cross-section etc) is connected with the imaginary part of electron energy shift.…”

“…[12,13,15]. The relativistic wave functions are calculated by solution of the Dirac equation with the potential, which includes the "outer electron -ionic core" potential (in the Miller-Green form [21]) and exchange-polarization potential [20]. All calculations utilize the Superatom-ISAN (version 93) code.…”

“…Note that the correct treatment of the heavy Rydberg atoms parameters in an external electromagnetic field requires using strictly relativistic models. Here we apply an energy approach [11][12][13][14][15] with the MP zeroth approximation [16][17][18][19][20] to computing the thermal BBR ionization characteristics of the Rydberg atoms, in particular, the sodium.…”

Study of spectra for lanthanides atoms with relativistic many- body perturbation theory: Rydberg resonances

“…The correlation corrections of the perturbation theory of second and higher orders are taken into account with the polarization and screening potentials (see Refs. [10][11][12][13][14][15][16]). Generally speaking, the majority of complex atomic systems possess a dense energy spectrum of interacting states with essentially relativistic properties.…”

“…In this approach, the whole calculation of the energies and decay probabilities of a non-degenerate excited state is reduced to the calculation and diagonalization of the complex matrix M. In published work by different authors, the Re{ΔE} calculation procedure has been generalized for the case of nearly degenerate states, whose levels form a more or less compact group. One of these variants has been introduced previously [4,13,14]: For a system with a dense energy spectrum, a group of nearly degenerate states is extracted and their matrix M is calculated and diagonalized. If the states are well separated in energy, the matrix M reduces to one term, equal to ΔE.…”