Suppression and Mitigation of Edge Localized Modes in the DIII-D Tokamak with 3D Magnetic Perturbations

Todd E. EVANS, the DIII-D Team
2012 Plasma and Fusion Research  
Uncontrolled Type-I Edge Localize Modes (ELMs) are expected to cause melting of the tungsten divertors in ITER. Methods for controlling ELMs in ITER include pellet pacing and Resonant Magnetic Perturbation (RMP) fields produced by in-vessel, non-axisymmetric, coils. Type-I ELMs have been reproducibly suppressed and mitigated in DIII-D H-mode plasmas with a variety of shapes and pedestal collisionalities using RMP fields of order 10 −3 B T . In these experiments the response of Type-I ELMs to
more » ... lied RMP fields, with a principal toroidal mode number n = 3, varies dramatically. In some cases there is an evolution in the ELM dynamics involving combinations of small high frequency D α spikes mixed with mitigated Type-I ELMs prior to reaching an ELM suppressed state. In other cases, there is continuous change in the frequency and amplitude of the Type-I ELMs. A reduced set of plasma parameters, that significantly affect the dynamics of the ELMs immediately following the application of the RMP field, have been identified. The dynamics of mitigated ELMs are generally consistent with those seen during Type-I through Type-V ELMs although several new types of ELM dynamics have also been observed in plasmas with relatively low toroidal fields as well as during q 95 ramps.
doi:10.1585/pfr.7.2402046 fatcat:2xki3kgagzcy3gldwb2obhmeoy