Re-evaluation of ITER ion cyclotron operating scenarios

Various ICRH scenarios for ITER-FEAT are evaluated. A wave propagation and damping study confirms the potential of the second harmonic tritium heating scenario for both heating and current drive purposes. The fundamental deuterium heating scheme is dominated by beryllium and alpha particle absorption. Owing to the reduced ITER size, the low frequency current drive window is lost in practice. A 3He minority greatly enhances the performance. In the early stage of the discharge, the power absorbed by the 3He is transferred to the background ions but, later on, the power of the fast particles (from both the 3He and the tritium tails) is roughly equally distributed between electrons and ions. Using the experimentally established expression for the L to H mode threshold, it is found that the H mode regime can always be reached using RF heating. To achieve Q=10, high density operation is required. Minority current drive competes with heating and with electron current drive. The scenarios foreseen for the non-activated ITER-FEAT phase are also discussed. (author)