Review of recent advances in the analytical theory of Stark broadening of spectral lines in plasmas: applications to laboratory discharges and astrophysical plasmas

Abstract

We present an overview of latest advances in the analytical theory of Stark broadening of spectral lines and their applications to various types of laboratory and astrophysical plasmas. They include: 1) in-depth study of intra-Stark spectroscopy in the x-ray range in relativistic laser-plasma interactions; 2) effect of diamagnetism on the number of observable hydrogen lines in plasmas; 3) influence of magnetic-field-caused modifications of trajectories of plasma electrons on the width of hydrogen/deuterium spectral lines: applications to white dwarfs; 4) Stark broadening of hydrogen/deuterium spectral lines by a relativistic electron beam: analytical results and applications to magnetic fusion; 5) counterintuitive dependence of the dynamical Stark width of hydrogenic spectral lines on the electron density.

Effects of Spiralling Trajectories on White Dwarf Spectra: High Rydberg States

“…The point is that for conditions of interest to white dwarfs, the magnetic perturbation is not necessarily small, and this results in a complete renormalization of the energy structure and profile. Ions are neglected in [3][4][5], and this is qualitatively correct, as discussed below. A very important point is that with spiralling trajectories, the collision volume, and hence contributing plasma particles, are different [15,16].…”

“…These arguments are made in the context of a theory shown repeatedly to be incorrect [7][8][9]. Furthermore, neither shielding nor the quadratic term in the magnetic field was considered in [3][4][5], both of which are shown here to be important and whose effects are analysed in detail. The present work accounts for both, as well as the correct statistics for the trajectory parametrization variables.…”

“…All calculations are carried out at an electron density of 2 × 10 17 e/cm 3 and a temperature of 1 eV. Three different magnetic field strengths are considered, namely 300, 500, and 2000 T, which are relevant for white dwarf conditions and were chosen so that the claimed validity condition [3][4][5] is fulfilled, as well as to showcase the importance of the quadratic B-term. (Debye) screening is explicitly included in all calculations shown here over the entire electron or ion path.…”

“…Stark broadening has been used for white dwarf diagnostics, modelling the complex Stark and Zeeman effect to infer plasma and magnetic field parameters, for example, in [1,2]. It has been recently suggested [3][4][5] that white dwarf diagnostics could be in error and should be revised, because of the effect of the magnetic field (which we take to be along the z-axis) to force spiralling trajectories [6] of the plasma particles (mainly electrons), predicting a dramatic width increase for high densities of Balmer-β and, most importantly, δ and lines. These arguments are made in the context of a theory shown repeatedly to be incorrect [7][8][9].…”

“…Refs. [3][4][5] employ the perturbation theory, but the idea is valid in general [10][11][12]. In Figure 1, we show diagonal matrix elements for the H δ line for a single (the same) realization of the plasma electron and ion microfield (called "configuration") with and without a magnetic field.…”