Theoretical investigation of spectroscopic properties of W$^{26+}$ in EBIT plasma

TL;DR

This paper provides a theoretical analysis of the spectroscopic properties of W$^{26+}$ ions in EBIT plasma, focusing on energy levels, transition probabilities, and the effects of electron correlation, with implications for plasma diagnostics.

Contribution

It introduces detailed multiconfiguration calculations of W$^{26+}$ ion spectra, highlighting the importance of correlation effects on transition probabilities and line identification in EBIT plasma.

Findings

Correlation effects significantly impact transition probabilities.

Identification of spectral lines observed in fusion plasma.

Spectra modeling indicates increased line intensities from certain transitions.

Abstract

Energy levels, radiative transition wavelengths and probabilities have been studied for the W$^{26+}$ ion using multiconfiguration Dirac-Fock and Dirac-Fock-Slater methods. Corona and collisional-radiative models have been applied to determine lines and corresponding configurations in a low-density electron beam ion trap (EBIT) plasma. Correlation effects for the $4f^{2}$, $4d^{9}4f^{3}$, $4f5l$ ($l=0,...,4$), $4fng$ ($n=5, 6, 7$) configurations have been estimated by presenting configuration interaction strengths. It was determined that correlation effects are important for the $4f5s \rightarrow 4f^{2}$ transitions corresponding to weak electric octupole transitions in a single-configuration approach. Correlation effects influence the $4f5d \rightarrow 4f^{2}$ transitions by increasing transition probabilities by an order of magnitude. Identification of some lines observed in fusion plasma has been proposed. Spectra modeling shows strong increase of lines originating from the $4f5s \rightarrow 4f^{2}$ transitions. Other transitions from the $10-30$ nm region can be of interest for the EBIT plasma.