Theoretical investigation on the soft X-ray spectrum of the highly-charged W54+ ions

Highlights: • A detailed level collisional-radiative model (CRM) had been constructed to investigate the observed spectrum from the EBIT with a mono-energy electron beam. • The observed spectrum from EBIT was explained by the present CRM and the other spectrum in 18.5–19.6 Å had been predicted to be observed in the EBIT experiment. • The different characteristics of soft X-ray spectrum from different plasma condition (i.e., EBIT and Maxwellian plasma) shown that the emission spectrum properties strongly depend on the plasma conditions, especially the energy distribution function of free electron in the plasma. A detailed level collisional-radiative model of the E1 transition spectrum of Ca-like W⁵⁴⁺ ion has been constructed. All the necessary atomic data has been calculated by relativistic configuration interaction (RCI) method with the implementation of Flexible Atomic Code (FAC). The results are in reasonable agreement with the available experimental and previous theoretical data. The synthetic spectrum has explained the EBIT spectrum in 29.5–32.5 Å , while several new strong transitions has been predicted to be observed in 18.5–19.6 Å for the future EBIT experiment with electron density n_e = 10¹² cm⁻³ and electron beam energy E_e = 18.2 keV.