Pellet fueling technology development for efficient fueling of burning plasma in ITER

Baylor, L. R.*; Parks, P. B.*; Jernigan, T. C.*; Caughman, J. B.*; Combs, S. K.*; Fenstermacher, M. E.*; Foust, C. R.*; Houlberg, W. A.*; Lasnier, C. J.*; Maruyama, So; Rasmussen, D. A.*

Pellet injection is the primary fuelling technique for efficient core fuelling of ITER burning plasma. Pellet survivability and pellet mass loss have been demonstrated using a mockup of ITER inboard injection line. This experiment has revealed that pellets survive intact up to 300m/s, which is required for inboard injection. The series of experiments have demonstrated that pellet mass loss at extremely high back pressure remains 20% (10% at 300m/s). The pellet mass deposition has been numerically evaluated. It shows that inboard launching, present ITER reference, of 3 mm and 5mm cylindrical pellets at 300 m/s has a capability to fuel well inside the separatrix. The fuelling efficiency is predicted to be nearly 100%, which will help to minimize the tritium retention of the first wall. Pellet injected in to the present day tokamaks have been found to trigger ELMs in H-mode plasma. ITER will have the pellet injection technology as an ELM mitigation system.