EAST高约束运行条件下离散阿尔芬本征模的数值模拟

Discrete Alfvén Eigenmodes in High Performance Scenarios with ITBs on EAST

运用磁流体力学数值模拟程序和磁流体力学-回旋动理学混合模拟程序对EAST(Experimental Advanced Superconducting Tokamak)装置上具有内部输运垒(ITB)高约束运行模式下的离散阿尔芬本征模(αTAE,α是等离子体压强梯度的参数)进行模拟研究。结果表明:在EAST上ITB以内的芯部区域存在丰富的αTAE,且在运行参数下多支αTAE被激发为不稳定模式。在EAST上预演的稳态运行方案中,αTAE分布在了更大的径向范围内,强的负磁剪切,减少了ITB局域内的αTAE。模拟对比了DIII-D装置和中国聚变工程试验堆(CFETR)上与EAST预演方案具有相似运行条件下的αTAE。结果发现与EAST上类似,在DIII-D与CFETR中,同样由于强的负磁剪切,在ITB内的强磁剪切区域并不存在αTAE。在CFETR核心区域出现了更高频率的αTAE,且在高能量粒子条件下激发出了更丰富的αTAE。

In this paper,the instability of the discrete Alfvén eigenmodes(αTAEs,whereαdenotes a parameter of plasma pressure gradient)are simulated in the high performance plasma with internal transport barriers(ITBs)on the EAST.The simulation results show that there is an abundance ofαTAEs on EAST,and it mainly locates in the core region within the ITB foot,where the temperature or the density gradient varies abruptly.Because the ITBs observed in the EAST are relatively localized and close to the core,the distribution ofαTAEs in the radial radius is narrow.In the high performance scenario with localized magnetic shear reversal,the ITB region is closer to the plasma edge,theαTAEs locate in a larger radial region.However,in the ITB region,due to the strong negative magnetic shear,theαTAEs are only found near the ITB foot;theαTAEs frequency decreases as the pressure gradient decreases closer to the ITB foot.In addition,theαTAEs in the scenarios with localized magnetic shear reversal on the DIII⁃D and China Fusion Engineering Test Reactor(CFETR)are also compared,and it is similar to that on EAST,where theαTAEs do not exist in the strong magnetic shear region.The simulations on CFETR show that there are higher frequenciesαTAEs in the core region and more abundantαTAEs are excited into unstable modes by energy particles.