Spatial characterization of a divertor in the presence of an X-point MARFE by collisional-radiative modeling and line profile calculations

Abstract High-resolution C IV n = 6–7 ( λ = 722.6 nm) line spectra measured in the divertor of JT-60U in presence of an X-point MARFE are analyzed using line profiles accounting for Stark and Doppler broadenings but excluding Zeeman effect which was suppressed experimentally. Spectra are fitted assuming either a single or two plasma layers depending on the crossed part of the MARFE. The ion temperature is taken equal to that of the electrons, the latter being deduced from C IV line intensity ratios. A density of 10 20 m −3 has been determined after fitting peripheral spectra with respect to the MARFE. For spectra related to central parts of the MARFE, two homogeneous plasma layers were assumed: a low-density layer ( N e ( l ) = 10 20 m - 3 ) and a high-density one with T e ( h ) = 1 - 3 eV . For few values of T e ( h ) , a fitting procedure was used in which T e ( l ) (low-density layer temperature) and N e ( h ) (high-density layer density) were searched for in the domains 1–25 eV and 10 20 –10 21 m −3 .