Plasma biasing effects on distribution of radiative losses in TdeV

Summary form only given. Control of impurity transport and, hence, radiative losses in tokamaks is becoming an increasingly important issue. This is because the reduction of radiative losses from the hot core is essential for achieving a reactor grade plasma, and at the same time high radiative losses in the divertor region are required in order to relax the heat load handling requirement for the divertor plates. On TdeV it has been shown that plasma biasing can be an important control instrument for achieving these two apparently contradictory requirements simultaneously. In order to characterize the distribution of the radiative losses in TdeV, the bolometry system has been upgraded. It has been observed that negative (or positive) plasma biasing reduces (or increases) the radiation from the plasma core by up to about 30%, whereas the radiative losses in front of the divertor plate, where E/spl times/B flow is directed, always increase by a factor of 2 to 3. Under standard operating conditions the radiated power from the plasma in front of the divertor plate is less than 1% of the ohmic input power.