Xu G S, Yang Q Q, Yan N, Wang Y F, Xu X Q, Guo H Y, Maingi R, Wang L, Qian J P, Gong X Z, Chan V S, Zhang T, Zang Q, Li Y Y, Zhang L, Hu G H, Wan B N
Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China.
University of Science and Technology of China, Hefei 230026, China.
Phys Rev Lett. 2019 Jun 28;122(25):255001. doi: 10.1103/PhysRevLett.122.255001.
A reproducible stationary high-confinement regime with small "edge-localized modes" (ELMs) has been achieved recently in the Experimental Advanced Superconducting Tokamak, which has a metal wall and low plasma rotation as projected for a fusion reactor. We have uncovered that this small ELM regime is enabled by a wide edge transport barrier (pedestal) with a low density gradient and a high density ratio between the pedestal foot and top. Nonlinear simulations reveal, for the first time, that the underlying mechanism for the observed small ELM crashes is the upper movement of the peeling boundary induced by an initial radially localized collapse in the pedestal, which stops the growth of instabilities and further collapse of the pedestal, thus providing a physics basis for mitigating ELMs in future steady-state fusion reactors.
最近，在具有金属壁且等离子体旋转速度较低（这是聚变反应堆预计具备的特性）的先进超导托卡马克实验装置中，实现了一种具有小“边界局域模”（ELM）的可重复稳态高约束模式。我们发现，这种小ELM模式是由一个宽的边缘输运垒（台基）实现的，该台基具有低密度梯度以及台基底部与顶部之间的高密度比。非线性模拟首次揭示，所观测到的小ELM崩溃的潜在机制是台基中初始径向局部坍缩引发的剥离边界向上移动，这阻止了不稳定性的增长以及台基的进一步坍缩，从而为未来稳态聚变反应堆中减轻ELM提供了物理基础。
