Effect of magnetic configuration on frequency of NBI-driven Alfvén modes in TJ-II
Effect of magnetic configuration on frequency of NBI-driven Alfvén modes in TJ-II
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磁配置对 TJ-II 中 NBI 驱动的 Alfvén 模式频率的影响
DOI：
10.1088/0029-5515/54/12/123002
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发表时间：
2014
期刊：
影响因子：
3.3
通讯作者：
B. Breizman
中科院分区：
文献类型：
--
作者：
A. Melnikov;M. Ochando;E. Ascasíbar;F. Castejón;A. Cappa;L. Eliseev;C. Hidalgo;L. Krupnik;A. López;M. Liniers;S. Lysenko;J. D. de Pablos;S. Perfilov;S. Sharapov;D. Spong;J. Jimenez;M. Ufimtsev;B. Breizman
在 TJ-II 螺旋中通过氢中性束注入 (NBI) 加热的氢等离子体中观察到了 Alfvénic 频率范围（30 kHz < fAE < 300 kHz）模式的激发。注入同场和反场 NBI，并且极向磁场的分量一一变化并组合变化，以便研究在旋转变换值的扩展范围内的光束驱动模式。利用独特的 TJ-II 功能，放电过程中变化的动态磁配置实验表明，真空变化和感应净等离子体电流对模式频率有强烈影响。当垂直场的微小（10%）变化引起低至±2 kA的等离子体电流时，某些模式观察到频率从~50 kHz急剧增加到~250 kHz。包括重离子束探针、磁性探针和多弦测辐射热计在内的一套全面的诊断功能使得识别模式的空间分布并推断其等离子体密度和磁场扰动的内部幅度成为可能。提出了一种基于局部 Alfvén 本征模 (AE) 色散关系的简单 fAE 分析模型来表征观测结果。结果表明，所有观察结果，包括真空 iota 和等离子体电流变化，都可以通过该模型进行拟合，因此线性模式频率对（等离子体电流）的依赖性和大于平方根密度的依赖性呈现出 TJ-II 中 NBI 诱导的 AE 的主要特征，并为进一步的实验与理论比较提供了框架。
Excitation of modes in the Alfvénic frequency range, 30 kHz < fAE < 300 kHz, was observed in hydrogen plasma heated by hydrogen neutral beam injection (NBI) in the TJ-II heliac. Co-field and counter-field NBI were injected, and the components of the poloidal magnetic field were varied one by one and in combinations, in order to investigate the beam-driven modes over an extended range of the rotational transform values, . Taking advantage of the unique TJ-II capabilities, a dynamic magnetic configuration experiment with variation during discharges has shown strong effects on the mode frequency via both vacuum changes and induced net plasma current. A drastic frequency increase from ∼50 to ∼250 kHz was observed for some modes when plasma current as low as ±2 kA was induced by small (10%) changes in the vertical field. A comprehensive set of diagnostics including a heavy ion beam probe, magnetic probes and a multi-chord bolometer made it possible to identify the spatial spread of the modes and deduce the internal amplitudes of their plasma density and magnetic field perturbations. A simple analytical model for fAE, based on the local Alfvén eigenmode (AE) dispersion relation, was proposed to characterize the observation. It was shown that all the observations, including vacuum iota and plasma current variations, may be fitted by the model, so the linear mode frequency dependence on (plasma current) and one over square root density dependence present the major features of the NBI-induced AEs in TJ-II, and provide the framework for further experiment-to-theory comparison.
影响因子：
3.3
作者：
Fujisawa, A.;Ido, T.;Schoch, P. M.
通讯作者：
Schoch, P. M.
仿星器/螺旋等离子体中高能离子驱动的全局不稳定性以及与托卡马克等离子体的比较
影响因子：
2.2
作者：
K.Toi;K.Ogawa;M.Isobe;et al
通讯作者：
et al