Effects of initial-state population variations on the 2p-->1s K alpha dielectronic satellite spectra of highly ionized iron ions in high-temperature astrophysical and laboratory plasmas.

Abstract

Theoretical predictions are presented for the iron K\ensuremath{\alpha} x-ray emission spectra from high-temperature plasmas, assuming steady-state optically thin excitation conditions. Account has been taken of all fine-structure components of the 2p\ensuremath{\rightarrow}1s inner-shell-electron radiative transitions in the iron ions from Fe xviii to Fe xxiv. The K\ensuremath{\alpha} emission spectra are assumed to be produced by means of dielectronic recombination and inner-shell-electron collisional excitation processes that involve intermediate autoionizing states belonging to electronic configurations of the type 1${s}^{1}$2${s}^{r}$2${p}^{s}$. In addition to the electron-temperature variation, which is attributable to the temperature dependences of the radiationless electron capture and inner-shell-electron collisional excitation rate coefficients and to the temperature dependence of the charge-state distribution, the K\ensuremath{\alpha} emission spectra exhibit an electron-density sensitivity. This electron-density sensitivity is a result of the density-dependent distribution of populations among the different fine-structure levels of the initial ions in the dielec- tronic recombination and inner-shell electron collisional excitation processes.