Critical issues in divertor optimisation for ITER–FEAT

Abstract A strong effect of the shape of the divertor floor near the separatrix strike point on power loading of the divertor targets in ITER–FEAT is found in the modelling studies. A similar effect has been demonstrated in JET experiments with Mark I and Mark II divertors (A. Loarte, Nucl. Fusion 38 (1998) 587; R. Monk, et al., in: Proceedings of the 24th EPS Conference on Controlled Fusion and Plasma Physics, Berchtesgaden, 1997, vol. 21A, p. 117) thus providing experimental verification of the modelling results. An operational window in six-dimensional phase space is found and different controls, like pumping speed or impurity seeding, are considered for ITER–FEAT.