MODELING OF TRANSITION FROM ATTACHED TO DETACHED STATE AND SELF-CONSISTENT CALCULATIONS OF HE LEVELS IN ITER

This paper describes models that address both power and particle contr ol with the ITER divertor. For power control, the characteristics of t he transition from attached to detached divertor operation are studied with an extension of our previous simple model [Y. Igitkhanov et al., 22nd EPS, Bournemouth (1995) p. IV-317]. This new model has been appl ied to JET experiments to show that the model can reproduce global fea tures of the transition. The model has been applied to ITER to identif y the range for detached operation in terms of the heating power, upst ream density, and impurity level, and the relation between divertor co ntrol and core plasma conditions. For particle control, we use the PRE TOR transport code together with a two point divertor model [K. Borras s and G. Janeschitz, Nucl. Fusion 34 (1991) 1203] for the edge boundar y conditions to study the sensitivity of the central helium concentrat ion to the pumping speed and helium enrichment in the divertor.