Studies on MHD Fluctuations through Direct Measurements of Eigenfunctions for Reduced MHD Equations Using Heavy Ion Beam

通过使用重离子束直接测量简化 MHD 方程的本征函数来研究 MHD 涨落

• 批准号: 13680565
• 负责人: IGUCHI Harukazu
• 金额: $ 0.64万
• 依托单位: National Institute for Fusion Science
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13680565/
• 关键词: Heavy Ion Beam Probe; Reduced MHD Equations; Stream function; Poloidal Flux Function; Scalar Potential; Vector Potential; MHD Fluctuations; Annular Momentum Conservation; 磁束関数; 静電ポテンシャル; 交換型不安定

Reduced MHD equations are commonly used as a powerful tool for the study of MHD instabilities both in theoretical researches and in computer simulations. In the framework of reduced MUD equations, two eigenfunctions are a stream function (Φ) and poloidal flux function (Ψ). In heavy ion beam probe diagnostic for axi-symmetric tori like tokamaks, observables are directly connected with the two eigenfunctions through energy and angular momentum conservations of the injected heavy ions. Those observables are a scalar potential (f) and toroidal component of vector potential (A_ζ). The heavy ion beam probe has been powerful in measurement of scalar potential, but measurements of A_ζ have been rare so far. This is because the observable in this method is a path-integrated one and does not give a local value.The purpose of this research program is to clarify the critical conditions for the observable to be connected with local measurement of A, and to provide experimental approach for MHD fluc … More tuation studies that can directly linked with theoretical approach using reduced MHD equations. Our method is as follows. Various types of MHD oscillations (spatial location and mode numbers) are assumed as model fluctuations. Then fluctuations in toroidal displacement of the secondary beam at the detector plates are numerically calculated by orbit analysis. The results are as follows:(1)When MHD oscillations are localized near the center of the plasma, locality of the measurements is fairly good(2)When MHD fluctuations are localized near the edge region of the plasma, some amount of spurious signal appears in the central region where fluctuations are absent in the model.(3)Locality of the measurements is improved when the ion gun and the detector are located far from the torus.These results suggest that locality of the measurements of A_ζ is rather good in a wide range of applications to axis-symmetric tori. Next step is to expand our investigation to non-axis-symmetric tori, where angular momentum conservation cannot be preserved. Less

约化MHD方程是研究MHD不稳定性的有力工具，无论是在理论研究还是在计算机模拟中都得到了广泛的应用。在简化的MUD方程的框架中，两个本征函数是流函数（Φ）和极向通量函数（Φ）。在轴对称环面托卡马克的重离子束探针诊断中，通过注入重离子的能量守恒和角动量守恒，将观测量与两个本征函数直接联系起来。这些观测量是标量势（f）和矢量势的环向分量（A_f）。重离子束探针在标量势的测量方面具有很强的能力，但对A_（10）的测量还很少见。这是因为该方法中的可观测量是一个路径积分的可观测量，不给出局部值，本研究的目的是阐明可观测量与局部测量A相联系的临界条件，为磁流体通量的测量提供实验途径 ...更多信息 这些研究可以直接与使用简化MHD方程的理论方法联系起来。我们的方法如下。各种类型的MHD振荡（空间位置和模式数）被假定为模型波动。然后通过轨道分析数值计算了二次束在探测板处的环形位移波动。结果表明：（1）当MHD振荡局域在等离子体中心附近时，测量的局部性较好;（2）当MHD振荡局域在等离子体边缘时，在模型中没有波动的中心区域会出现一定量的寄生信号。（3）当离子枪和探测器远离圆环面时，测量的局部性得到改善，这些结果表明，在轴对称圆环面的广泛应用中，A_∞测量的局部性是相当好的。下一步是将我们的研究扩展到非轴对称环面，在那里角动量守恒不能保持。少

项目成果

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