SPECTROSCOPIC STUDY OF RADIATIVE LOSSES IN THE JT-60U DIVERTOR PLASMA

Spatial distributions of absolute line intensities of D I and C II-IV in the divertor region have been measured simultaneously with a 38-cha nnel optical fibre array in JT-60U. The radiative losses in the divert or region have been derived from the intensities. In L-mode discharges without the MARFE, the fractions of the radiative losses due to deute rium and carbon are 36% and 64%, respectively. The carbon radiation is related to the carbon influx by a simple impurity model based on the confinement time of the carbon ion on the assumption of the physical s puttering. The power radiated due to carbon accounts for a large incre ase in the radiative losses by the MARFE.