Collisional-radiative model including recombination processes for W27+ ion

Abstract

We have constructed a collisional-radiative (CR) model for W27+ ions including 226 configurations with n ≤ 9 and l ≤ 5 for spectroscopic diagnostics. We newly include recombination processes in the model and this is the first result of extreme ultraviolet spectrum calculated for recombining plasma component. Calculated spectra in 40–70 A range in ionizing and recombining plasma components show similar 3 strong lines and 1 line weak in recombining plasma component at 45–50 A and many weak lines at 50–65 A for both components. Recombination processes do not contribute much to the spectrum at around 60 A for W27+ ion. Dielectronic satellite lines are also minor contribution to the spectrum of recombining plasma component. Dielectronic recombination (DR) rate coefficient from W28+ to W27+ ions is also calculated with the same atomic data in the CR model. We found that larger set of energy levels including many autoionizing states gave larger DR rate coefficients but our rate agree within factor 6 with other works at electron temperature around 1 keV in which W27+ and W28+ ions are usually observed in plasmas.