Ergodization of magnetic surfaces in tokamaks
Ergodization of magnetic surfaces in tokamaks
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DOI：
10.1088/0032-1028/18/7/006
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发表时间：
1976-07
期刊：
影响因子：
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通讯作者：
A. Samain
中科院分区：
文献类型：
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作者：
A. Samain
本文讨论了托卡马克中观察到的内部扰动和负尖峰的湍流机制。如果磁通线在两个磁表面r=r1和r=r2 r1<r2之间变得各态历经，这种各态历经倾向于使r1和r2之间的电流密度分布变平，并且这最终感应出大的电场E，在r=r1侧为正，在r=r2侧为负。场E通过趋肤效应在r=r1和r=r2附近的未扰动域中感应电流密度的空间脉冲。这些脉冲可以驱动不稳定的撕裂模式与大的横波数，因此扩展域（r1r2）的遍历发生。这种现象的第一步可能是磁岛分界线的撕裂不稳定性，这些磁岛通常存在于磁表面q=1或q=2附近。
A turbulence mechanism which could explain the internal disruptions and the negative spikes which are observed in Tokamaks is discussed. If the flux lines become ergodic between two magnetic surfaces r=r1 and r=r2 r1<r2, this ergodicity tends to flatten the current density profile between r1 and r2, and this eventually induces a large electric field E, positive on the side r=r1 and negative on the side r=r2. The field E induces by skin effect spatial pulses of current density in the unperturbed domain near r=r1 and r=r2. These pulses may drive unstable tearing modes with large transverse wave numbers, and so extend the domain (r1r2) where the ergodicity takes place. The first step of the phenomena could be a tearing instability of the separatrix of the magnetic islands which are normally present near the magnetic surfaces q=1 or q=2.