Destabilization of reversed shear Alfven eigenmodes driven by energetic ions during NBI in HL-2A plasmas with q(min) similar to 1

作者：Chen, W.^*; Yu, LiMin; Liu, Yi; Ding, X. T.; Xie, H. S.; Zhu, J.; Yu, L. M.; Ji, X. Q.; Li, J. X.; Li, Y. G.; Yu, D. L.; Shi, Z. B.; Song, X. M.; Cao, J. Y.; Song, S. D.; Dong, Y. B.; Zhong, W. L.; Jiang, M.; Cui, Z. Y.; Huang, Y.; Zhou, Y.; Dong, J. Q.; Xu, M.; Xia, F.; Yan, L. W.; Yang, Q. W.; Duan, X. R.

来源：Nuclear Fusion, 2014, 54(10): 104002.

DOI：10.1088/0029-5515/54/10/104002

• frequency sweeping modes
• RSAE
• Alfven continuum
• energetic ions

Two groups of frequency sweeping modes are observed and interpreted in the HL-2A plasmas with q(min) similar to 1. The tokamak simulation code calculations indicate the presence of a reversed shear q-profile during the existence of these modes. The mode frequencies lie in between TAE and BAE frequencies, i.e. omega(BAE) < omega < omega(TAE), and these modes are highly localized near q(min), i.e. r/a similar to 0.25. A group of modes characterized by down-sweeping frequency with q(min) decrease due to q(min) > 1 and nq(min) - m > 0, and another group of modes characterized by up-sweeping frequency with q(min) drop, owing to q(min) < 1 and nq(min) - m < 0 before sawtooth crash. The kinetic Alfven eigenmode code analysis supports that the down-sweeping modes are kinetic reverse shear Alfven eigenmodes (KRSAEs), and the up-sweeping modes are RSAEs, which exist in the ideal or kinetic MHD limit. In addition, the down-and up-sweeping RSAEs both have fast nonlinear frequency behaviour in the process of slow frequency sweeping, i.e. producing pitch-fork phenomena. These studies provide valuable constraint conditions for the q-profile measurements.

• 出版日期2014-10
• 单位浙江大学; 核工业西南物理研究院; 华东理工大学