Statistical characterization of blob turbulence across the separatrix in HL-2A tokamak
Statistical characterization of blob turbulence across the separatrix in HL-2A tokamak
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DOI：
10.1088/0741-3335/52/5/055003
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发表时间：
2010-05
影响因子：
2.2
通讯作者：
J. Cheng;L. Yan;W. Hong;K. Zhao;T. Lan;J. Qian;A. Liu;H. Zhao;Yi Liu;Q. Yang;
中科院分区：
文献类型：
--
作者：
J. Cheng;L. Yan;W. Hong;K. Zhao;T. Lan;J. Qian;A. Liu;H. Zhao;Yi Liu;Q. Yang;
用往复式朗缪尔五探针阵列研究了HL-2A装置等离子体分界面上的液滴统计特性。逆压力梯度尺度长度的径向分布在最后一个闭合通量面（LCFS）内有一个最大值，这里的偏斜度接近于零。条件平均揭示了密度空穴和密度斑点仅在LCFS内部产生，并且它们以相反的方向传播。水滴的极向速度在穿过分界线时变号，这与E × B漂移流一致。穿过分界线的密度和电势波动之间的相移的戏剧性变化表明了当磁力线从闭合变为开放时湍流的独特性质。弱三波相互作用的小波双相干强时间不对称斑点的依赖性是首次观察到的。此外，有效的斑点产生率估计为8.0 × 103 s-1，由喷射斑点引起的对流粒子通量可导致约58%的径向粒子通量损失。
Blob statistical characteristics across the separatrix of HL-2A tokamak plasma have been studied using a reciprocating Langmuir five-probe array. The radial profile of inverse pressure gradient scale length has a maximum just inside the last closed flux surface (LCFS), where the skewness is close to zero. Conditional average reveals that the density holes and blobs are produced just inside the LCFS and they propagate in opposite directions. The poloidal velocity of blobs changes its sign when it is across the separatrix, which is consistent with E × B drift flow. The dramatic change in phase shift between density and potential fluctuations across the separatrix suggests the distinct properties of turbulence when the magnetic field line changes from a closed to an open one. The dependence of a weak three-wave interaction in terms of wavelet bicoherence on strong time-asymmetry blobs is observed for the first time. Moreover, the effective blob generation rate is estimated as 8.0 × 103 s−1 and the convective particle flux induced by the ejective blobs can lead to about 58% loss of radial particle flux.