A review of ELMs in divertor tokamaks
A review of ELMs in divertor tokamaks
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DOI：
10.1016/s0022-3115(97)80039-6
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发表时间：
1997-02
影响因子：
3.1
通讯作者：
D. Hill
中科院分区：
文献类型：
--
作者：
D. Hill
边缘局域模（ELMs）是边缘物理界日益关注的焦点，因为ELMs产生的偏滤器热脉冲对未来高功率托卡马克（如ITER）的偏滤器设计有潜在的影响。本文回顾了ELMs的已知情况，重点介绍了ELMs对刮落层和偏滤器等离子体的影响。ELM效应已在ASDEX-U、C-Mod、COMPASS-D、DIII-D、JET、JFT-2 M、JT-60 U和TCV托卡马克中进行了测量，并在此报告。至少有三种类型的ELMs已经确定，并确定其显着特点。1型巨ELM能使等离子体存储能量突然损失10-15%，但其振幅（ΔW W）不随加热功率的增加而增加。在H模式功率阈值附近观察到3型ELM，并产生小的能量转储（存储能量的1-3%）。所有的ELM增加了刮削层等离子体，并在偏滤器靶上产生粒子通量，其比ELM之间的静止相大10倍。偏滤器的热脉冲是最大的内部目标，不像L-模式或静态H-模式;一些托卡马克报告的径向结构的热通量分布，这是暗示的岛屿或螺旋结构。1型ELM振幅和频率的功率标度已经在几个托卡马克中测量，最近已被应用于ITER中ELM尺寸的预测。对预期ELM振幅的关注导致了一些旨在证明ELM主动控制的实验。在ASDEX-U的辐射损失的反馈控制的杂质气体注入表明，一个有前途的操作模式（CDH模式）与非常小的3型ELMs可以保持加热功率远高于H模式阈值，其中巨大的1型ELMs通常观察。虽然ELM具有许多潜在的负面影响，但ELM在提供密度控制和限制高约束H模式放电中的芯等离子体杂质含量方面的有益作用不应被忽视。
Edge localized modes (ELMs) are the focus of increasing attention by the edge physics community because of the potential impact that the large divertor heat pulses due to ELMs would have on the divertor design of future high power tokamaks such as ITER. This paper reviews what is known about ELMs, with an emphasis on their effect on the scrape-off layer and divertor plasmas. ELM effects have been measured in the ASDEX-U, C-Mod, COMPASS-D, DIII-D, JET, JFT-2M, JT-60U and TCV tokamaks, and are reported here. At least three types of ELMs have been identified and their salient features determined. Type 1 giant ELMs can cause the sudden loss of up to 10–15% of the plasma stored energy, but their amplitude (ΔW W ) does not increase with heating power. Type 3 ELMs are observed near the H-mode power threshold and produce small energy dumps (1–3% of the stored energy). All ELMs increase the scrape-off layer plasma and produce particle fluxes on the divertor targets which are as much as ten times larger than the quiescent phase between ELMs. The divertor heat pulse is largest on the inner target, unlike that of L-mode or quiescent H-mode; some tokamaks report radial structure in the heat flux profile which is suggestive of islands or helical structures. The power scaling of type 1 ELM amplitude and frequency has been measured in several tokamaks and has recently been applied to predictions of the ELM size in ITER. Concern over the expected ELM amplitude has led to a number of experiments aimed at demonstrating active control of ELMs. Impurity gas injection with feedback control on the radiation loss in ASDEX-U suggests that a promising mode of operation (the CDH-mode) with very small type 3 ELMs can be maintained with heating power well above the H-mode threshold, where giant type 1 ELMs are normally observed. While ELMs have many potential negative effects, the beneficial effect of ELMs in providing density control and limiting the core plasma impurity content in high confinement H-mode discharges should not be overlooked.