Simulation of toroidal Alfvén eigenmode instability in the HL-2A tokamak

doi:10.16568/j.0254-6086.202304011

Abstract

Abstract: The linear wave properties of toroidal Alfvén eigenmodes (TAEs) in HL-2A tokamak are investigated using the eigenvalue code GAM. The simulation results are consistent with the experimental observations. Moreover, the continuum spectra, mode structures and frequencies of TAEs with different safety factor profiles are also analyzed. For the normal magnetic shear, it is found that the radial mode structure of TAE in the core ( _{$\sqrt{{{\psi }_{\text{T}}}}$} < 0.3 ) consists of two main adjacent poloidal harmonics, while the radial mode structure of TAE in the outer region ( $\sqrt{{{\psi }_{\text{T}}}}$ = 0.3~0.9) consists of eight higher poloidal harmonics, indicating that the magnetic shear plays an important role in poloidal harmonics coupling. When the core-reversed magnetic shear exists in the safety factor profile, TAE disappears therein and the mode radial width of TAE in the outer region becomes narrow. In the end, the effect of electron density profile on TAE is also investigated, which shows that the profile mode frequency decreases with the increase of electron density, while the mode structure is not sensitive to the change of electron density

Key words: HL-2A tokamak, Toroidal Alfvén eigenmode, Safety factor, Mode structure

摘要： 为了帮助理解 HL-2A 装置的实验现象，采用本征值程序 GAM 对 HL-2A 实验中环形阿尔芬本征模 (TAE)的线性性质进行了模拟研究，模拟结果与实验结果一致。此外，分析了具有不同安全因子剖面的 TAE 的连续谱、模结构和模频率。对于正常磁剪切，发现芯部( $\sqrt{{{\psi }_{\text{T}}}}$<0.3)的 TAE 的径向模结构由两个相邻的极向谐波组成，而外区($\sqrt{{{\psi }_{\text{T}}}}$ =0.3~0.9)的 TAE 的径向模结构由 8 个较高的极向谐波组成，这表明磁剪切在极向谐波耦合中起着重要作用。当安全因子剖面在芯部存在反剪切时，反剪切区域的 TAE 消失，外区的 TAE 的径向宽度变窄。最后，研究了电子密度剖面对 TAE 的影响，发现 TAE 模频率随电子密度的增加而降低，而模结构对电子密度的变化不敏感。

关键词: HL-2A 装置, 环形阿尔芬本征模, 安全因子, 模结构

CLC Number:

TL62+ 2

GUAN Jing-yu , KE Rui , BAO Jian , CHEN Wei , YE Min-you. Simulation of toroidal Alfvén eigenmode instability in the HL-2A tokamak [J]. Nuclear Fusion and Plasma Physics, 2023, 43(4): 436-443.

管敬雨, 柯锐, 包健, 陈伟, 叶民友. HL-2A 环形阿尔芬本征模不稳定性的模拟研究[J]. 核工业西南物理研究院, 2023, 43(4): 436-443.

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