We have modelled self-consistently the most efficient ways to fuel ITER Hydrogen (H), Helium (He) and Deuterium-Tritium (DT) plasmas with gas and/or pellet injection with the integrated core and 2D SOL/divertor suite of codes JINTRAC. As far as we are aware, for ITER this is the first time modelling of the entire plasma has been carried out to follow the plasma evolution from X-point formation, through L-mode, L-H transition, steady-state H-mode, H-L transition and current ramp-down. We gave attention to keeping within ITER operational limits, in particular maintaining the target power loads below 10MW/m2 by Ne seeding or main gas rate.
For the Pre-Fusion Plasma Operation phase our aim was to develop robust scenarios, including those required for the commissioning of systems with plasma. Our simulations show that commissioning and operation of the ITER Neutral Beam (NB) system to full power should be possible in 15 MA/5.3T L-mode H plasmas with pellet fuelling and 20MW of ECRH. For He plasmas gas fuelling alone is enough to allow access to H-mode conditions at 7.5 MA/2.65T with 53-73 MW of additional heating, as after application of NB and during the ensuing L-H transition, the modelled density build-up quickly reduces the NB shine-through losses to acceptable levels. These He H-modes should allow the characterisation of ITER H-mode plasmas and the demonstration of ELM control schemes to take place in the non-active phase before ITER DT operation.
In ITER DT plasmas we have explored, by varying the fuelling and heating schemes, the best route to achieve the target fusion gain of Q=10 and how to exit the plasma from such conditions with acceptable divertor loads. The use of pellet fuelling in DT can provide a faster route to increase the density in L-modes, but it is not essential for unrestricted NB operation due to the lower shine-through losses compared to H. During the H-L transition and current ramp-down, gas fuelling and Ne seeding are required to keep the divertor power loads under the engineering limits but precise control over radiation is needed to prevent the plasma becoming thermally unstable.