Electron-impact excitation of W 44+ and W 45+

Plans to employ tungsten in the divertor region of the International Thermonuclear Experimental Reactor require radiative and collisional data for modelling x-ray emissions of highly ionized stages of tungsten. In an earlier paper, we reported on the results of fully relativistic R -matrix calculations for W 46+ that included the effects of radiation damping on the resonance contributions. In this paper, we present the results of similar fully relativistic, radiatively damped R -matrix calculations for W 44+ and W 45+ . Radiation damping is found to be small for W 45+ , but is appreciable for many of the excitations from the ground and metastable levels of W 44+ . Rates from the present calculations will be combined with those from the calculations for W 46+ and employed for collisional-radiative modelling for these ions.