剪切磁场位形下电阻壁模不稳定性的数值模拟

Numerical studies on resistive wall mode instability with magnetic shears

数值研究了平衡磁场位形对电阻壁模稳定性的影响。研究发现,磁场剪切对电阻壁模有解稳作用,对于不同的剪切磁场位形,最不稳定的电阻壁模的环向模数和极向模数不同。等离子流对电阻壁模的增长有抑制作用,稳定住电阻壁模的临界流速度随着磁场剪切率的增大而增大。电阻壁模经线性增长后,进入非线性演化阶段,最后达到饱和状态,剪切磁场位形下的扰动磁能比均匀磁场位形下的扰动磁能饱和度高。

The effects of magnetic shear on the resistive wall mode （RWM） are numerically studied in a slab geometry. The most unstable mode is different with different magnetic shear rate λ. The shear in the magnetic field has an unstable effect on the linear evolution of the RWM. On the other hand, the critical flow velocity for stabilizing the RWM increases with increasing of shear rate λ. The RWM saturates in the nonlinear phase. The saturation can be attributed to flux piling-up on the resistive wall. The saturation level increases with increasing of shear rate λ.