28th IAEA Fusion Energy Conference (FEC 2020)

Excitation of Beta-Induced Alfven Eigenmodes by Magnetic Island

12 May 2021, 08:30

4h

Virtual Event

Regular Poster Magnetic Fusion Theory and Modelling P3 Posters 3

Speaker

Prof. Huishan Cai (University of Science and Technology of China)

Description

The mechanism of excitation of beta-induced Alfv\'{e}n eigenmodes (BAEs) with magnetic island larger than a threshold without energetic ions is studied. It is found that the nonlinear coupling between Geodesic acoustic mode and magnetic island can drive the pair of BAEs. To excite the BAEs, the phase of BAEs to island should be $\pi /2$ and the magnetic island is larger than a threshold. The results are consistent with the experimental results shown in EAST. It implies that other tokamaks similar experimental results, that BAEs excitation by magnetic island without energetic ions, may be from the nonlinear coupling between island and waves. It also implies that the exist of magnetic island can make the excitation of BAEs more easier in plasma with energetic ions, since magnetic island also can increase the pressure gradient of energetic ions near the island separatrix. This predicts that BAEs may appear more frequently in the presence of magnetic island in ITER.