Progress in resolving power and particle control issues for the International Thermonuclear Experimental Reactor

Recent tokamak divertor experiments with ''detached'' and ''partially detached'' divertor regimes show that a major portion of the heating power can be radiated to the walls to reduce the peak heat loads on divertor plates and that a combination of fueling and pumping can control the plasma density and exhaust impurities such as He. Tokamak transport codes and divertor modeling codes have been developed that dan reproduce and predict the major features of these experiments. The combination of these recent experiments and the use of the models to extrapolate to ITER have led to the development of a concept for the International Thermonuclear Experimental Reactor [R. Aymar, Fusion Technol. 30, 397 (1996)] power and particle control system, which relies upon a single null ''vertical target'' divertor with gas and pellet fueling and active pumping. The experiments indicate that energy confinement can be adversely affected if the recycling neutrals and impurities are not well confined in the divertor, so that efficient confinement of neutrals in the divertor is a key feature of the divertor design.