Observation of toroidal Alfven eigenmode excited by energetic electrons induced by static magnetic perturbations in the EAST tokamak
Observation of toroidal Alfven eigenmode excited by energetic electrons induced by static magnetic perturbations in the EAST tokamak
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EAST 托卡马克中静磁扰动引起的高能电子激发的环形阿尔文本征模的观测
DOI：
10.1088/1741-4326/aad70c
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发表时间：
2018
期刊：
影响因子：
3.3
通讯作者：
Zhou R. J.
中科院分区：
文献类型：
--
作者：
Chu N.;Sun Y.;Gu S.;Wang H. H.;Hu Y. J.;Shi T. H.;Chen D. L.;Gu X.;He K. Y.;Jia M.;Lin S. Y.;Liu H. Q.;Qian J. P.;Ren J.;Shen B.;Ti A.;Wang S. X.;Xie J. L.;Xu M.;Xue M. M.;Yan N.;Zang Q.;Zeng L.;Zhang J. Z.;Zhang T.;Zhang Y.;Zhong G. Q.;Zhou C.;Zhou R. J.
首次在托卡马克欧姆加热等离子体中观察到在施加静磁扰动（MP）期间由几乎捕获的高能电子激发的环形阿尔文本征模（TAE）。当静态 n= 2 MPs 的电流超过阈值时，就会出现这种 TAE，此时会发生强制 n= 2 磁重联。这里，n 是环形模式数。该TAE位于等离子体边缘附近，这与TAE间隙的计算一致。它沿离子反磁方向传播，具有主导环形模数 n= 2。 TAE 的频率与能量约为 150 keV 的勉强捕获的高能电子的进动频率一致。在 n= 2 磁重联之后就观察到该能量范围内硬 X 射线发射强度的增加。高能电子可以通过重新连接后形成的磁岛来加速。高能电子含量减少后，TAE 趋于稳定。这一观察结果表明，静态 MP 的应用可能为我们提供一种主动控制聚变等离子体中阿尔文本征模的新方法。
A toroidal Alfvén eigenmode (TAE) excited by barely trapped energetic electrons during the application of a static magnetic perturbations (MPs) is observed for the first time in tokamak ohmic heating plasmas. This TAE appears when the current of a static n= 2 MPs exceeds a threshold value, at which a forced n= 2 magnetic reconnection happens. Here, n is the toroidal mode number. This TAE is located near the plasma edge, which agrees with the calculation of the TAE gap. It propagates in the ion diamagnetic direction and has a dominant toroidal mode number n= 2. The frequency of the TAE is consistent with the precessional frequency of the barely trapped energetic electrons with energy around 150 keV. An increase of the hard x-ray emission intensity in this energy range is observed just after the n= 2 magnetic reconnection. The energetic electrons may be accelerated by the magnetic islands formed after reconnection. The TAE is stabilized after a reduction in the contents of energetic electrons. This observation suggests that the application of static MPs may provide us with a novel method to actively control Alfvén eigenmodes in fusion plasmas.