ITER Gonfinement and Stability Modelling

The results of self-consistent transport and stability studies of the ITER reference inductive and steady-state reversed shear scenarios are discussed. The semi-empirical transport models used for ITER simulations with 1.5D transport codes ASTRA and PRETOR are described. The analysis reveals a weak dependence of plasma performance on the radial profiles of transport coefficients provided the coefficients are adjusted to make the computed energy confinement time equal to that given by a global H-mode scaling relation (IIn= 1). It is shown that the ITER reference inductive scenario with O = 10, Pru, = 400 MW, Ie = 15 MA is stable against the high and low n ideal MHD modes without a conducting wall. Steady-state operation with Q > 5 would require a reduced current 1e - 9 MA, enhanced confinement with llr - 1.5, BN - 3, high bootstrap fraction - 5OVo and a reversed magnetic shear configuration. This configuration is ideally unstable without a wall and stable with a conducting wall at 1.4a.