CORSICA modelling of ITER hybrid operation scenarios

Abstract

The hybrid operating mode observed in several tokamaks is characterized by further enhancement over the high plasma confinement (H-mode) associated with reduced magneto-hydro-dynamic (MHD) instabilities linked to a stationary flat safety factor () profile in the core region. The proposed ITER hybrid operation is currently aiming at operating for a long burn duration (>1000 s) with a moderate fusion power multiplication factor, , of at least 5. This paper presents candidate ITER hybrid operation scenarios developed using a free-boundary transport modelling code, CORSICA, taking all relevant physics and engineering constraints into account. The ITER hybrid operation scenarios have been developed by tailoring the 15 MA baseline ITER inductive H-mode scenario. Accessible operation conditions for ITER hybrid operation and achievable range of plasma parameters have been investigated considering uncertainties on the plasma confinement and transport. ITER operation capability for avoiding the poloidal field coil current, field and force limits has been examined by applying different current ramp rates, flat-top plasma currents and densities, and pre-magnetization of the poloidal field coils. Various combinations of heating and current drive (H&CD) schemes have been applied to study several physics issues, such as the plasma current density profile tailoring, enhancement of the plasma energy confinement and fusion power generation. A parameterized edge pedestal model based on EPED1 added to the CORSICA code has been applied to hybrid operation scenarios. Finally, fully self-consistent free-boundary transport simulations have been performed to provide information on the poloidal field coil voltage demands and to study the controllability with the ITER controllers.

Multi-machine analysis of termination scenarios with comparison to simulations of controlled shutdown of ITER discharges

“…The fastest ITER current ramp-down is limited by the PF coil voltages and the requirements to control shape, position and VS stability with a certain precision. In ITER, a fully controlled current ramp-down from I p = 15 MA to below I p = 1 MA can be achieved in ~60 s. An example of a typical ITER termination, modelled with the Corsica code [7,8], is shown in figure 1. The current ramp-down has a duration of 210 s, with a moderate current ramp-down rate of 0.07 MA s −1 .…”

Analysis of Alfven eigenmode destabilization in ITER using a Landau closure model

“…Several advanced operation scenarios have been proposed for ITER [45,46,47,48,49,50,51]. Among them, the reverse shear [52,53,54], hybrid [55,56,57] and steady state operation [58,59,60] scenarios are the configurations with the best potential performance.…”

Evolution of magnetic Kubo number of stochastic magnetic fields during the edge pedestal collapse simulation

“…Experimental measurements of correlation lengths in fusion-grade hot plasmas are typically performed by replacing the ensemble average operator with a temporaldomain average operator assuming that the data are ergodic, stationary and homogeneous. [35][36][37] Since we only have 201 points in time in the simulation data, i.e., τ A = [0, 1, 2, ..., 199, 200], the temporal-domain average is not suitable to obtain statistically valid results. Furthermore, running tens of the same simulation to obtain the ensemble average is computationally too expensive.…”