Comparative Modeling of Type I ELM control by stochastic fields in DIII-D, JET and ITER

The recent successful experiments on Type I ELM (edge localized mode) control in DIII-D using a stochastic boundary created by external I-coils represents a great interest for the next-step tokamak ITER. The physical explanation of the Type I ELMs suppression on DIII-D still remains an open question. Numerical simulations concerning the suppression of Type I ELM modes for 3 machines DIII-D, JET and ITER are presented in this paper. The numerical results of heat transport modelling in the presence of Type I ELMs and the radial magnetic perturbation from external coils are presented for JET and ITER and compared to the DIII-D case. Possible designs of the external coils for JET and ITER are analyzed taking into account technical and space constraints for the implantation of such coils in JET and ITER. For the external ergodic coils proposed for JET ∼ 200 kA current is needed for the same level of the edge magnetic perturbation for the n = -3 and q95 ∼ 3 scenario compared to the I-coils current of 3 kA used for the ELM suppression in DIII-D. For a similar scenario and proposed design ∼ 400 kA is needed for ELM suppression in ITER. This large difference in the ergodic coils current compared to the DIII-D in-vessel design is due to the much larger distance of the external coils from plasma in JET and ITER. (A.C.)