Radial profiles and emissivity ratio analysis of Ne-like FeXVII n = 3−2 transitions in Large Helical Device

The radial profiles of the FeXVII 3s-2p and 3d-2p transitions emitted in the wavelength range of 15 − 17 A have been observed in the Large Helical Device (LHD). The chord-integrated radial profiles are converted into radial emissivity profiles by means of Abel inversion. The emissivity ratios among FeXVII n = 3−2 transitions calculated from the radial emissivity profiles are compared with calculations based on a collisional-radiative (CR) model developed for Fe ions. The result reasonably confirms the effect of electron temperature and density on the emissivity ratio. However, the emissivity of the 3C (2p 53d 1 P 1 → 2p 6) transition is obviously lower than the prediction from the CR model. This discrepancy is consistent with measurements in the solar corona and other laboratory plasmas.