Nonlinear destabilization of linearly stable tearing modes with multiple rational surfaces
Nonlinear destabilization of linearly stable tearing modes with multiple rational surfaces
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DOI：
10.1063/1.870723
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发表时间：
1994-05
影响因子：
2.2
通讯作者：
M. Persson;R. Dewar
中科院分区：
文献类型：
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作者：
M. Persson;R. Dewar
分析了具有多个共振磁面结构的有限尺寸磁岛的稳定性。证明了存在线性稳定的构型，但在有限大小的扰动下可能不稳定。给出了两个具有两个q=2表面的构型的单螺旋双撕裂的两个不同的例子。在第一种情况下，不稳定是由于磁分离延伸到不稳定电流梯度的区域。对于第二种情况，通过微分等离子体旋转抑制有理表面的线性耦合，从而使模式线性稳定，这基本上解耦了围绕不同有理表面的扰动。有限大小的磁岛将与初始等离子体旋转发生拟线性相互作用。然后，等离子体旋转被平衡，模式不稳定。
The stability of finite size magnetic islands is analyzed in configurations with multiple resonant magnetic surfaces. It is demonstrated that there are configurations that are linearly stable which can be unstable to finite size perturbations. Two different examples of single helicity double tearing are given for configurations with two q=2 surfaces. In the first case the destabilization is due to the extension of magnetic separatrices out to regions of destabilizng current gradients. For the second case the modes are linearly stabilized by the suppression of the linear coupling of the rational surfaces by differential plasma rotation, which essentially decouples the perturbations around the different rational surfaces. A finite size magnetic island will interact quasilinearly with initial plasma rotation. The plasma rotation is then equilibrated and the mode destabilized.