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

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 , 4f 5l (l = 0, ..., 4), 4f ng (n = 5, 6, 7) configurations have been estimated by presenting configuration interaction strengths. It was determined that correlation effects are important for the 4f 5s → 4f 2 transitions corresponding to weak electric octupole transitions in a single-configuration approach. Correlation effects influence the 4f 5d → 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 4f 5s → 4f 2 transitions. Other transitions from the 10 − 30 nm region can be of interest for the EBIT plasma.