Extraction of large-scale coherent structure from plasma turbulence using rake probe and wavelet analysis in a tokamak
Extraction of large-scale coherent structure from plasma turbulence using rake probe and wavelet analysis in a tokamak
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DOI：
10.1063/1.2213217
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发表时间：
2006-06
影响因子：
1.6
通讯作者：
G. Xu;B. Wan;W. Zhang
中科院分区：
文献类型：
--
作者：
G. Xu;B. Wan;W. Zhang
在聚变等离子体中，在静电湍流中间歇出现的大尺度相干结构有时占总输运的50%以上，因此对这些相干结构的研究对于理解等离子体的约束具有重要意义。需要新的实验技术来从波动信号中提取这些相干结构。在这项工作中，在HT-7超导托卡马克上使用了12个极向RAKE探头来测量等离子体边缘区域的等离子体湍流。提出了几种基于双正交小波的信号分析方法，并将其应用于探头数据。由于所选择的子波的结构与湍流波包的结构非常相似，因此可以从周围的湍流中选择性地提取关于大尺度相干结构的信息。利用所选择的小波和小尺度细节的小波重构了大尺度相干结构的时空图像。这些基于小波的技术可以应用于各种类型的图像处理。
In fusion plasmas, intermittently occurring large-scale coherent structures in electrostatic turbulence sometimes contribute more than 50% of total transport, so the investigation on these coherent structures is important for understanding plasma confinement. New experimental techniques are required to extract these coherent structures from fluctuating signals. In this work a 12-tip poloidal rake probe was used on the HT-7 superconducting tokamak to measure plasma turbulence in the plasma edge region. Several signal analysis methods based on a biorthogonal wavelet were developed and applied to the probe data. Since the structure of the selected wavelet is every similar to that of the turbulence wave packet, information about large-scale coherent structures can be selectively extracted from the ambient turbulence. The spatiotemporal patterns of the large-scale coherent structures were reconstructed using the selected wavelets as well as those of small-scale details. These wavelet-based techniques can be ap...