Development of the ITER Baseline Inductive Scenario

Full text: Sustainment of Q = 10 (fusion power/input power) operation with a power level of ∼ 500 MW for several hundred seconds is a key mission goal of the ITER Project. Past calculations and simulations predict that these conditions can be produced in high-confinement mode operation (H-mode) at 15MA relying primarily on inductive current drive. Detailed predictive simulations, supported by experimental demonstrations in existing tokamaks, have been used to assemble an end-to-end specification of the scenario consistent with the final design of the ITER device. Simulations have encompassed plasma initiation, current ramp-up, plasma burn and current ramp-down, and have included density profiles and thermal transport models consistent with edge pedestal conditions present in current fusion experiments that maintain quasi-stationary conditions due to the presence of edge localized modes. Convergence on final designs for the ITER central solenoid and poloidal field coils has allowed the operating space for 15MA high-Q operation to be specified more accurately. To assess operational flexibility within the final operating space, several variations of the reference time-dependent scenario simulations have been analyzed to vary assumptions concerning pedestal parameters and to explore alternative operation on ITER. A range of pedestal transport assumptions was simulated in order to bound the range of operation due to uncertainties in the prediction of pedestal formation. The simulations also provide detailed information for final modifications of engineering subsystems that are being implemented on ITER. Data from these free-boundary control simulations yield configurational data required to assess first wall designs and diagnostic implementations. ITER will have an initial period of non-nuclear operation in hydrogen or helium to allow commissioning of all tokamak systems with plasma in advance of deuterium and deuterium-tritium operation. This paper will discuss details of these scenario simulations and the operational space boundary calculations for ITER operation. These conclusions will be illustrated by detailed comparisons of simulations that predict an operating envelope for ITER inductive discharge conditions. (author)