Modelling 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 control with the ITER divertor. For power control, the characteristics of the 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 applied to JET experiments to show that the model can reproduce global features of the transition. The model has been applied to ITER to identify the range for detached operation in terms of the heating power, upstream density, and impurity level, and the relation between divertor control and core plasma conditions. For particle control, we use the PRETOR transport code together with a two point divertor model [K. Borrass and G. Janeschitz, Nucl. Fusion 34 (1991) 1203] for the edge boundary conditions to study the sensitivity of the central helium concentration to the pumping speed and helium enrichment in the divertor.