Performance of ITER as a burning plasma experiment

Recent performance analysis has improved confidence in achieving Q (= fusion power/auxiliary heating power)⩾ 10 in inductive operation in ITER. Performance analysis based on empirical scalings shows the feasibility of achieving Q ⩾ 10 in inductive operation, particularly with improved modelling of helium exhaust. Analysis has also indicated the possibility that ITER can potentially demonstrate Q ∼ 50, enabling studies of self-heated plasmas. Theory-based core modelling indicates the need for a high pedestal temperature (3.2–5.3 keV) to achieve Q ⩾ 10, which is in the range of projections with presently available pedestal scalings. Pellet injection from the high-field side would be useful in enhancing Q and reducing edge localized mode (ELM) heat load in high plasma current operation. If the ELM heat load is not acceptable, it could be made tolerable by further tilting the target plate. Steady state operation scenarios at Q = 5 have been developed with modest requirements on confinement improvement and beta (HH98(y,2) ⩾ 1.3 and βN ⩾ 2.6). Stabilization of the resistive wall modes (RWMs), required in such regimes, is feasible with the present saddle coils and power supplies with double-wall structures taken into account. Recent analysis shows a potential of high power steady state operation with a fusion power of 0.7 GW at Q ∼ 8. Achievement of the required βN ∼ 3.6 by RWM stabilization is a possibility. Further analysis is also needed on reduction of the divertor target heat load.