EAST托卡马克上鱼骨模不稳定性对芯部重杂质输运的影响

The energetic driven fishbones mode was first found on the PDX tokamak. The stability of bursting fishbones including precessional ones, diamagnetic ones and pressure ones is well known and has been the subject of several studies on many different devices: JET, ASDEX, DIIID and HL-2A. Less investigated are the effects of fishbones on the background plasma, especially on the core high-Z impurities transport. Recently, it is reported on MAST that a transport of high- Z impurities from the low- to the high-field side and leads to asymmetric accumulation of high-Z impurities on the inboard side is apparent direct link between bursting fishbones. .The NBI beam ions driven fishbone was observed in EAST which equipped with W up divertor and Mo first wall in 2014 campaign. Hence, the study of the effect of fishbone on the core high-Z impurities transport and understanding the related physics are the right time. Since ITER will be characterized by a substantial population of fast particles, these observations open the possibility that a similar effect might occur in ITER thus affecting impurity transport and ultimately the energy confinement. This effect is particularly crucial for ITER due to the tungsten divertor and the compatibility of metal walls with ITER scenarios is under investigation.

高能粒子激发的鱼骨模不稳定性自第一次在PDX装置上发现后，其物理机制的研究包括在JET，ASDEX，DIIID，HL-2A等各大装置上进行了充分的开展，并建立了三种典型的模型：进动鱼骨模，逆磁鱼骨模和压强鱼骨模。 然而鱼骨模对背景等离子体影响，特别是对芯部重杂质输运影响的研究却相对较少。MAST装置上最新的实验结果显示，鱼骨模爆发会导致重杂质从低场到高场输运进而造成极向非对称累积。.EAST托卡马克装备有钨上偏滤器和钼第一壁，并且在2014年的实验中已经观测到了NBI束粒子激发的鱼骨模爆发。因此在EAST上开展鱼骨模对芯部重杂质输运影响的实验，分析其背后可能的物理机理是恰逢其时的。由于ITER等离子体中会有很大份额的高能粒子，这些结果也将对钨或者其他兼容金属偏滤器运行的ITER在芯部重杂质输运甚至能量约束方面研究有重要的借鉴意义。

等离子体芯部重杂质以及氦灰的排出是ITER以及CFETR运行的重点。本项目首次在EAST上观测到高能离子驱动鱼骨模不稳定性，建立了用于三维杂质输运研究的软X射线切向系统；发现鱼骨模不稳定性可以有效排出EAST芯部钨杂质，进而为混合先进高约束模式运行提供了保障。鱼骨模不稳定性将会是芯部重杂质和氦灰排出的备选手段。