Compact toroid fuelling for ITER

Deep fuelling of ITER may be achievable by compact toroid (CT) injection. The advantages of deep fuelling include avoiding edge density limits by fuelling beyond the transport barriers, profile peaking to reach ignition, profile control to improve current drive, low tritium inventory, etc. In this paper, a conceptual design of a CT fueller for ITER is presented. In the proposed design, a CT injector fires 2.2-mg toroids of DT fuel into ITER at a rate of up to 20 Hz and a speed of 300 km s−1. Each CT adds ≈0.3% to the Tokamak plasma inventory. The fuelling rate is 20 Pa m3 s−1, which is based on achieving 10% burnup by deep fuelling (beyond r/a∼0.5), and with a parallel gas puffing system. Each CT is ≈ 7% of the minor radius in size. The CT Fueller system would consume 8 MWe, with ≈2 MW deposited in the Tokamak.