Hu J S, Sun Z, Guo H Y, Li J G, Wan B N, Wang H Q, Ding S Y, Xu G S, Liang Y F, Mansfield D K, Maingi R, Zou X L, Wang L, Ren J, Zuo G Z, Zhang L, Duan Y M, Shi T H, Hu L Q
Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, China.
Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, China and General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA.
Phys Rev Lett. 2015 Feb 6;114(5):055001. doi: 10.1103/PhysRevLett.114.055001. Epub 2015 Feb 3.
A critical challenge facing the basic long-pulse high-confinement operation scenario (H mode) for ITER is to control a magnetohydrodynamic (MHD) instability, known as the edge localized mode (ELM), which leads to cyclical high peak heat and particle fluxes at the plasma facing components. A breakthrough is made in the Experimental Advanced Superconducting Tokamak in achieving a new steady-state H mode without the presence of ELMs for a duration exceeding hundreds of energy confinement times, by using a novel technique of continuous real-time injection of a lithium (Li) aerosol into the edge plasma. The steady-state ELM-free H mode is accompanied by a strong edge coherent MHD mode (ECM) at a frequency of 35-40 kHz with a poloidal wavelength of 10.2 cm in the ion diamagnetic drift direction, providing continuous heat and particle exhaust, thus preventing the transient heat deposition on plasma facing components and impurity accumulation in the confined plasma. It is truly remarkable that Li injection appears to promote the growth of the ECM, owing to the increase in Li concentration and hence collisionality at the edge, as predicted by GYRO simulations. This new steady-state ELM-free H-mode regime, enabled by real-time Li injection, may open a new avenue for next-step fusion development.
国际热核聚变实验堆（ITER）基本长脉冲高约束运行模式（H模式）面临的一个关键挑战是控制一种磁流体动力学（MHD）不稳定性，即边界局域模（ELM），它会导致面向等离子体部件出现周期性的高峰值热通量和粒子通量。通过使用一种向边缘等离子体连续实时注入锂（Li）气溶胶的新技术，先进超导托卡马克实验装置取得了一项突破，实现了一种新的稳态H模式，在不存在ELM的情况下持续时间超过数百个能量约束时间。稳态无ELM的H模式伴随着一种强烈的边缘相干MHD模式（ECM），其频率为35 - 40千赫兹，在离子抗磁漂移方向上极向波长为10.2厘米，可实现连续的热排出和粒子排出，从而防止面向等离子体部件上的瞬态热沉积以及约束等离子体中的杂质积累。正如GYRO模拟所预测的，由于边缘处锂浓度增加以及碰撞性增强，锂注入似乎促进了ECM的增长，这一点着实令人瞩目。这种通过实时锂注入实现的新的稳态无ELM的H模式运行机制，可能为下一步核聚变发展开辟一条新途径。
