KLL dielectronic recombination resonant strengths of He-like up to O-like tungsten ions

Abstract

Dielectronic recombination (DR) is an important process in hot plasma physics as well as in atomic structure and collision theory. This work reports the studies of the KLL DR resonance strengths of He-, Li-, Be-, B-, C-, N-, and O-like tungsten ions, through both experiment and calculation. The experimental resonance strengths were determined within uncertainty below 11% at the Shanghai electron beam ion trap by employing a fast electron beam-energy scanning technique. A fully relativistic configuration interaction method implemented in the flexible atomic code was employed to calculate DR process and also radiative recombination (RR). The consideration of the interference effect between DR and RR was revealed to be necessary to determine the resonance strength.

K-shell excitation dielectronic recombination resonance strengths of highly charged He-like to O-like Xe ions

“…The electron beam energy is monochromatic and tunable, making EBIT a unique tool to study the electron ion collision processes [24]. The current experimental setup was similar to those used in our previous work [22,25], as shown in figure 1. In the experiment, neutral xenon atoms, injected into the EBIT drift tube in a gas phase, were subsequently ionized into required charge states by electron-ion collisions in 4.2 s with a 30.5 keV electron beam.…”

Dielectronic recombination strengths and plasma rate coefficients of multiply charged ions

“…Close to the threshold, however, the isolated-resonance approach is formally no longer valid and should then be replaced by some unified treatment of the DR and radiative recombination (RR) since the transition amplitude of both processes diverge for ε i → 0 (Alber, Cooper & Rau, 1984;Nahar & Pradhan, 1994). For heavy ions in particular, the interference of DR and RR may result in an asymmetric Fano profile (Knapp et al 1995;Pindzola et al 1995;Schippers et al 2004;Tu et al 2016). Such a unified treatment usually requires a more advanced mathematical machinery, but does not seriously affect the DR spectra at finite electron energies or in plasma.…”

Study on KLL dielectronic recombination for highly charged tungsten ions at Shanghai EBIT

“…In these researches, resonance energy and strength of DR, Breit interaction, polarization and interference effect between DR and RR have been studied [1][2][3][4][5][6].…”

“…The measurement was performed on Shanghai electron beam ion trap [7] by employing a fast electron beamenergy scanning technique. During the experiment, W(CO) 6 was continuously injected into the EBIT, and the electron beam energy was fast scanned through the resonant energies of KLL DR of He-like up to O-like W ions, while the X ray photons were detected by a HPGe detector. A fully relativistic configuration interaction method implemented in the flexible atomic code was employed to calculate DR process and also radiative recombination (RR).…”