The mechanism of excitation of beta-induced Alfvn eigenmodes (BAEs) with magnetic islands larger than a threshold without energetic ions is studied. It is found that the nonlinear coupling between geodesic acoustic mode and magnetic islands can drive the pair of BAEs. The phase of BAEs to island should be π/2 to excite the BAEs and the magnetic island is larger than a threshold. The results are consistent with the experimental results shown in EAST(#86309). It implies that similar experimental results in other tokamaks, that BAEs excitation by magnetic islands without energetic ions, may be from the nonlinear coupling between islands and waves. It also implies that the existence of magnetic islands can make the excitation of BAEs easier in plasma with energetic ions, since the magnetic island can also increase the pressure gradient of energetic ions near the island separatrix. This predicts that BAEs may appear more frequently in the presence of magnetic islands in ITER.

研究了磁岛大于阈值而无高能离子的β诱导的Alfvn本征模式（BAE）的激发机理。发现测地声模与磁岛之间的非线性耦合可以驱动一对BAE。BAE与岛的相位应为π/ 2以激发BAE，并且磁岛大于阈值。结果与EAST（＃86309）中显示的实验结果一致。这暗示着在其他托卡马克中的类似实验结果，即没有高能离子的磁性岛对BAE的激发，可能来自岛与波之间的非线性耦合。这也暗示了磁岛的存在可以使含高能离子的等离子体中的BAE激发更加容易，因为磁岛还可以增加岛分离线附近的高能离子的压力梯度。这预示着，在ITER中存在磁岛的情况下，BAE可能会更频繁地出现。