Screening of resonant magnetic perturbations by flows in tokamaks
Screening of resonant magnetic perturbations by flows in tokamaks
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DOI：
10.1088/0029-5515/52/5/054003
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发表时间：
2012-05-01
期刊：
影响因子：
3.3
通讯作者：
Kaveeva, E.
中科院分区：
文献类型：
--
作者：
Becoulet, M.;Orain, F.;Kaveeva, E.
将圆柱几何的非线性简化四场RMHD模型扩展到包括等离子体旋转、新经典极向粘度和两种流体抗磁效应。研究了托卡马克中静态共振磁扰动与旋转等离子体的相互作用。模型考虑了RMP穿透引起的平衡电场自洽演化。结果表明，在压力梯度较大的基底区，垂直于磁场的平均流量(右箭头上的（E) x右箭头上的(B)）和电子抗磁分量在等离子体筛选RMP中起着至关重要的作用。一般来说，电阻率越低、旋转越强、RMP幅值越小，筛分效果越好。观察到中央岛屿的强屏蔽限制了RMP渗透到分隔线附近的狭窄区域。然而，在一定的等离子体参数下，由于rmp产生的径向电场的非线性演化，右箭头上的(E) x右箭头上的(B)旋转可以通过局部的电子反磁旋转来补偿。在这种情况下，RMPs可以穿透并形成磁岛。本文采用DIII-D、JET和ITER的典型等离子体参数和RMPs谱进行了模拟。
The non-linear reduced four-field RMHD model in cylindrical geometry was extended to include plasma rotation, neoclassical poloidal viscosity and two fluid diamagnetic effects. Interaction of the static resonant magnetic perturbations (RMPs) with the rotating plasmas in tokamaks was studied. The self-consistent evolution of equilibrium electric field due to RMP penetration is taken into account in the model. It is demonstrated that in the pedestal region with steep pressure gradients, mean flows perpendicular to the magnetic field, which includes (E) over right arrow x (B) over right arrow and electron diamagnetic components plays an essential role in RMP screening by plasma. Generally, the screening effect increases for lower resistivity, stronger rotation and smaller RMP amplitude. Strong screening of central islands was observed limiting RMP penetration to the narrow region near the separatrix. However, at certain plasma parameters and due to the non-linear evolution of the radial electric field produced by RMPs, the (E) over right arrow x (B) over right arrow rotation can be compensated by electron diamagnetic rotation locally. In this case, RMPs can penetrate and form magnetic islands. Typical plasma parameters and RMPs spectra on DIII-D, JET and ITER were used in modelling examples presented in the paper.