Recent progress in understanding shear flow dynamics in a magnetic island in toroidal fusion plasmas

Gyungjin Choi^1*, Minki Jung², Jaehyun Kim³

¹Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea
²Department of Nuclear Engineering, Seoul National University, Seoul, Korea
³Korea Institute of Fusion Energy, Daejeon, Korea

* Presenter:Gyungjin Choi, email:gyungjinc@kaist.ac.kr

Recently, there have been significant advances in the high-performance operation of toroidal fusion plasmas with a magnetic island worldwide. Motivated by this, we present recent progress in physics understanding of dynamics and roles of shear flows in the vicinity of a magnetic island in toroidal magnetic fusion plasmas, namely, tokamaks and stellarators. Since the shear flows are well known to be crucial in turbulence suppression and transport barrier formation in the fusion plasmas, our focus would be on the various candidate mechanisms of confinement enhancement in the presence of a magnetic island, rather than addressing the negative effects of the island on confinement, which are relatively better known from the past. Accordingly, recent progress will also be summarized from the perspective of multi-scale interactions among microturbulence, shear flows, and the magnetic island, highlighting the roles of the shear flows mediating the interactions. The aim is to guide the audience to the forefront of this topic based on recent advances in analytic theories and findings from experiments and simulations.

Keywords: Nuclear Fusion, Magnetic Island, Turbulence, Self-organization, Multi-scale Interaction