35 / 2021-04-16 08:36:30

Optimization of ELM control via using 3D fields for various ITER scenarios

ELM control;,ITER

Type-I edge localized modes (ELMs) is potentially dangerous to the future tokamak devices such as ITER [1], since a large amount of particles and energy can be released from the plasma region into the plasma facing components during the period of large ELMs bursts. It has been extensively demonstrated that the resonant magnetic perturbation (RMP) technique is a relatively mature method for controlling type-I ELMs [2-6]. Following linear plasma response modeling for many tokamak devices utilizing the single fluid MHD code MARS-F [7], two criteria have been established that can be used to predict the choice of the ELM control coil configuration. One is to maximize the resonant radial magnetic perturbed field near the plasma ede, and the other is to maximize the plasma boundary surface displacement near the X-point. These two criteria often predict similar optimal coil phasing [8].

In this work, the plasma surface displacement near the X-point is used to optimize the RMP ELM control configuration in ITER [9-10]. A systematic investigation is carried out for all 8 ITER scenarios including all stages of ITER operation, with varying ratio of plasma current and toroidal magnetic field. With three rows of magnetic coils in ITER, the optimal coil phasing is found to be roughly linearly scales with the edge safety factor q₉₅. In order to understand effects of RMPs on the plasma momentum and particle confinement, quasi-linear initial value simulations are also carried out utilizing the MARS-Q code [11] for all 8 ITER scenarios. Results show a weak effect of the RMP on the plasma core flow in all scenarios. The RMP effect on the plasma density varies depending on the plasma scenario and the coil current configuration.

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