Excitation of beta-induced Alfven eigenmodes by the coupling between geodesic acoustic mode and magnetic island
Excitation of beta-induced Alfven eigenmodes by the coupling between geodesic acoustic mode and magnetic island
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DOI：
10.1088/1741-4326/abd3e9
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发表时间：
2021-03-01
期刊：
影响因子：
3.3
通讯作者：
Kong, Defeng
中科院分区：
文献类型：
--
作者：
Cai, Huishan;Gao, Baofeng;Kong, Defeng
研究了在没有高能离子的情况下磁岛大于阈值的 β 诱导阿尔文本征模 (BAE) 的激发机制。研究发现，测地线声模与磁岛之间的非线性耦合可以驱动这对 BAE。 BAE 到岛的相位应为 pi/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。这意味着在其他托卡马克中的类似实验结果，即由没有高能离子的磁岛激发的BAE可能来自于岛与波之间的非线性耦合。这也意味着磁岛的存在可以使高能离子等离子体中的BAE更容易被激发，因为磁岛还可以增加岛分界线附近高能离子的压力梯度。这预示着 ITER 中存在磁岛时，BAE 可能会更频繁地出现。
The mechanism of excitation of beta-induced Alfven 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 pi/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.