Neutral diffusion and anomalous effects on ion flow shear
Neutral diffusion and anomalous effects on ion flow shear
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中性扩散和离子流剪切的异常效应
DOI：
10.1063/1.873053
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发表时间：
1998
影响因子：
2.2
通讯作者：
P. Helander
中科院分区：
文献类型：
--
作者：
T. Fülöp;P. Catto;P. Helander
在中性原子丰富的托卡马克边缘区，离子-中性相互作用可以改变大块离子流。在这个区域，离子流的标准新古典表达式与实验观察不一致。先前在高原地区的研究[Valanju et al., Phys.][fluid][4,2675(1992)]表明，这种差异主要是由离子中性电荷交换造成的动量损失造成的。在本工作中，我们证明了在没有中性扩散的情况下，如果中性平均自由程较短且中性密度比等离子体密度低，电荷交换不会显著影响离子的新古典输运。然而，由通量面平均动量约束决定的中性扩散和异常过程在高原地区的包含可以极大地改变分离矩阵内的平行离子流。此外，流动中的局部剪切可能由中性扩散和异常效应之间的平衡决定。
Bulk ion flow can be modified by ion–neutral interactions in the edge region of tokamaks where neutral atoms are abundant. In this region, the standard neoclassical expression for the ion flow is not consistent with the experimental observations. Previous work in the plateau regime [Valanju et al., Phys. Fluids B 4, 2675 (1992)] suggests that the discrepancy is caused mainly by momentum loss due to ion–neutral charge exchange. In the present work we show that in the absence of neutral diffusion, charge exchange cannot affect the neoclassical transport of the ions significantly if the neutral mean-free path is short and the neutral density is low compared to the plasma density. However, the inclusion of neutral diffusion and anomalous processes in the plateau regime can substantially modify parallel ion flow inside the separatrix as determined by the flux surface averaged momentum constraint. Moreover, the local shear in the flow may be determined by a balance between neutral diffusion and anomalous effect...