Integrated core-SOL modelling of fuelling, density control and divertor heat loads for the flat-top phase of the ITER H-mode D-T plasma scenarios

The operation of a tokamak designed to test the sustainability of a thermonuclear grade plasma like the international tokamak experimental reactor (ITER) presents several challenges. Among them is the necessity of fuelling the plasma to reach the density required to generate enough fusion power to achieve and, at the same time, to avoid excessive power loads at the divertor targets (beyond 10 MW m). Whether this goal is achievable or not depends on the details of the fuelling scheme, of the atomic species that are injected into the plasma, of the power radiation pattern in the scrape-off layer and in the divertor, of the additional heating schemes and of the transport mechanisms at work in the core and near the edge of the plasma. In this study we present, for different operational scenarios, the results of an integrated modelling approach to the problem taking into account all the different aspects of it, albeit with some limitations and simplifications discussed in the paper. The tool adopted for our simulations is the JINTRAC suite of codes, which can simulate in an integrated fashion the transport of particles and heat in different regions of the plasma. Within the limitation of our modelling our assessment is that, by carefully tuning the gas fuelling and impurity seeding, it is indeed possible for ITER to achieve and at the same time maintain acceptable divertor power loads. We also investigate the sensitivity of this result to some of the uncertainties in the modelling assumptions underlying the simulations presented in the paper.