Theoretical analysis and predictive modelling of ELMs mitigation by enhanced toroidal ripple and ergodic magnetic field

Parail, V. V.*; Evans, T. E.*; Johnson, T.*; Lnnroth, J.*; Oyama, Naoyuki; Saibene, G.*; Sartori, R.*; Salmi, A.*; de Vries, P.*; Becoulet, M.*; Corrigan, G.*; Hastie, J.*; Gimblett, C.*; Greenfield, C. M.*; Hatae, Takaki; Howell, D.*; Hynnen, V.*; Kamada, Yutaka; Kiviniemi, T.*; Kurki-Suonio, T.*; Loarte, A.*; Nardon, E.*; Shinohara, Koji; JET-EFDA Contributors*

Ripple-induced transport and externally driven resonance magnetic perturbations (RMP) near the separatrix are considered as prospective methods of ELM mitigation in present day tokamaks and ITER. Although these methods rely on different physics to generate extra transport, the influence of this transport on plasma dynamics and ELM mitigation is either similar or supplementary. The results of extensive theoretical analysis of the underlying physics processes behind transport induced by ripple and RMP is presented together with predictive transport modelling. Comparison with experiments on present-day tokamaks is given.