Simultaneous measurements of unstable and stable Alfvén eigenmodes in JET
Simultaneous measurements of unstable and stable Alfvén eigenmodes in JET
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在 JET 中同时测量不稳定和稳定的 Alfvén 本征模
DOI：
10.1088/1741-4326/ac899e
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发表时间：
2022
期刊：
影响因子：
3.3
通讯作者：
J. Contributors
中科院分区：
文献类型：
--
作者：
R. Tinguely;J. Gonzalez;P. Puglia;N. Fil;S. Dowson;M. Porkolab;I. Kumar;M. Podestà;M. Baruzzo;A. Fasoli;Y. Kazakov;M. Nave;M. Nocente;J. Ongena;vZ. vStancar;J. Contributors
在本文中，我们报告了在 JET 托卡马克等离子体中同时测量的不稳定和稳定环形引起的阿尔文本征模 (TAE) 的新颖实验观察。三离子加热方案 (D-DNBI-3He) 用于将氘核加速到 MeV 能量，从而使环形模式数 n = 3–5 的 TAE 不稳定，每个模式振幅都会减小。同时，Alfvén 特征模式主动诊断共振激发稳定的 n = 6 TAE，总归一化阻尼率 −γ/ω 0 ≈ 1%–4%。使用代码 NOVA-K 和 MEGA 的混合动力学 MHD 建模都发现了与实验中具有相似频率、模态结构和径向位置的本征模态。 NOVA-K 与 n = 3、4 和 6 TAE 表现出良好的一致性，在不确定性范围内匹配 n = 6 模式的阻尼率，并将辐射阻尼确定为主要贡献。所有模式与 MEGA 的一致性都有所改善：不稳定的 n = 3-5 模式和稳定的 n = 2, 6 模式，后两种模式分别通过较高的固有阻尼和较低的快离子驱动来稳定。虽然一些差异仍有待解决，但这种独特的验证工作让我们对未来融合装置的 TAE 稳定性预测充满信心。
In this paper, we report the novel experimental observation of both unstable and stable toroidicity-induced Alfvén eigenmodes (TAEs) measured simultaneously in a JET tokamak plasma. The three-ion-heating scheme (D-DNBI-3He) is employed to accelerate deuterons to MeV energies, thereby destabilizing TAEs with toroidal mode numbers n = 3–5, each decreasing in mode amplitude. At the same time, the Alfvén eigenmode active diagnostic resonantly excites a stable n = 6 TAE with total normalized damping rate −γ/ω 0 ≈ 1%–4%. Hybrid kinetic-MHD modeling with codes NOVA-K and MEGA both find eigenmodes with similar frequencies, mode structures, and radial locations as in experiment. NOVA-K demonstrates good agreement with the n = 3, 4, and 6 TAEs, matching the damping rate of the n = 6 mode within uncertainties and identifying radiative damping as the dominant contribution. Improved agreement is found with MEGA for all modes: the unstable n = 3–5 and stable n = 2, 6 modes, with the latter two stabilized by higher intrinsic damping and lower fast ion drive, respectively. While some discrepancies remain to be resolved, this unique validation effort gives us confidence in TAE stability predictions for future fusion devices.