Numerical calculation for instability criterion of tearing modes influenced by energetic ions
Numerical calculation for instability criterion of tearing modes influenced by energetic ions
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DOI：
10.1088/1361-6587/acfff2
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发表时间：
2023-10
影响因子：
2.2
通讯作者：
Yuehao Ma;Runzhe Zhang;H. Cai
中科院分区：
文献类型：
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作者：
Yuehao Ma;Runzhe Zhang;H. Cai
撕裂模式的不稳定性准则，包括循环高能离子 (CEI) 的影响，通过迭代方法和快速傅里叶变换算法进行数值求解。系统地研究了 CEI 的 beta（压力与磁压力之比）分布和磁剪切对撕裂模式不稳定准则的影响。 CEI 通过改变总扰动平行电流密度来影响撕裂模式，并且它们在有理表面（撕裂模式的位置）处的 beta 分布的梯度起着重要作用。 CEI对撕裂模式的影响取决于CEIs的沉积位置和环形循环方向。具体来说，轴上峰值 co-CEI 对撕裂模式具有稳定作用。对于离轴峰值co-CEIs，为了稳定撕裂模式，co-CEIs的沉积位置应位于磁轴和有理面之间，并且存在稳定效果最强的最佳峰宽和沉积位置。对于反CEIs，当沉积位置位于磁轴和有理面之间时，它们会破坏撕裂模式的稳定性。然而，如果沉积位置位于外有理面附近，则反CEIs 对撕裂模式具有稳定作用。此外，CEIs 存在着一个关键的沉积位置。 CEIs发挥稳定作用还是不稳定作用取决于沉积位置在临界沉积位置之内或之外。临界沉积位置与CEIs的轨道宽度有关。最后，磁剪切可以稳定撕裂模式，但随着磁剪切的增加，co-CEI 对撕裂模式的影响减弱。
The instability criterion of tearing modes, including the effects of circulating energetic ions (CEIs), is numerically solved through an iterative method and fast Fourier transform algorithm. The influence of beta (the ratio of pressure to the magnetic pressure) profile of CEIs and magnetic shear on instability criterion of the tearing modes are investigated systematically. CEIs impact the tearing modes through altering the total perturbed parallel current density, and the gradient of their beta profile at the rational surface (the location of tearing mode) plays an important role. The effect of CEIs on tearing modes depends on the deposition position and the toroidal circulating direction of CEIs. Specifically, the on-axis peaked co-CEIs have a stabilizing effect on tearing modes. For off-axis peaked co-CEIs, in order to stabilize the tearing modes, the deposition position of co-CEIs should be located between the magnetic axis and rational surface, and there is an optimal peak width and deposition location where the stabilizing effect is strongest. For counter-CEIs, they would destabilize the tearing modes when the deposition position is located between the magnetic axis and rational surface. However, if the deposition position is located near the outside rational surface, counter-CEIs have a stabilizing effect on tearing modes. Furthermore, there exists a critical deposition position for CEIs. Whether CEIs plays a stable role or an unstable role depends on the deposition position within or outside the critical deposition position. The critical deposition position is related to the orbital width of CEIs. Finally, the magnetic shear can stabilize the tearing modes, but the effect of co-CEIs on tearing modes is weakened as the magnetic shear increases.