Intrinsic molybdenum impurity density and radiative power losses with their scalings in ohmically and ICRF heated Alcator C-Mod and FTU tokamak plasmas

A new radiative cooling curve for molybdenum, determined from the Hebrew Un iversity, Jerusalem-Lawrence Livermore atomic code (HULLAC) has been used t o estimate the radiative power losses from various ion cyclotron resonance frequency (ICRF) and ohmically heated Alcator C-Mod tokamak plasmas and ohm ically heated Frascati tokamak upgrade (FTU) plasmas. This cooling curve ha s been found to accurately predict the radiative losses from molybdenum ion s in plasma. Radiative losses from molybdenum computed by using the HULLAC cooling curve could typically account for greater than 60% of the total rad iative losses as measured by bolometry in Alcator C-Mod tokamak plasmas. Th e molybdenum density was found to be as high as similar to 10(11) particles cm(-3) (n(Mo)/n(e) similar to 0.001) in ICRF heated plasmas. Plasmas after botonization of the plasma facing surfaces had the lowest molybdenum densi ty and radiated power of all the plasmas examined; ICRF heated plasmas had the highest. The molybdenum density and radiative power losses were found t o increase roughly linearly with input ICRF power during different heating schemes in plasmas with both I-I-mode and L-mode confinement. Although the molybdenum densities were found to decrease with increasing electron densit y, the radiative power losses did not change significantly for II types of plasmas studied in Alcator C-Mod and FTU: diverted plasmas heated with ICRF and both limited and diverted plasmas heated ohmically.