Plasma wall interactions in ITER
Plasma wall interactions in ITER
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DOI：
10.1088/0031-8949/2006/t124/001
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发表时间：
1997-02
期刊：
影响因子：
2.9
通讯作者：
G. Federici
中科院分区：
文献类型：
--
作者：
G. Federici
设计热核等离子体和固体材料环境之间的界面可以说是ITER和未来聚变动力反应堆成功发展的最高技术挑战之一。碳基材料被认为具有优越的上级热机械性能并且不会熔化，但它们通过与侵蚀的碳共沉积而保留了高水平的氚，这可能会严重限制等离子体操作。ITER中的碳纤维复合材料（CFC）偏滤器靶只有通过减缓/抑制大边缘局域模（ELM）的方法才能存活足够长的时间。金属材料，如钨，将避免氚保留问题，但由于大ELM和中断的熔融层损失可能导致严重的损坏和不可接受的短寿命。用高Z材料保持等离子体纯度仍然是一个问题。在ITER中提出了几种不同的面向等离子体的材料的混合物，以优化具有不同功率和粒子通量特性的区域的要求（即，对于第一壁，CFC对于偏滤器撞击点瓦片，W对于偏滤器中的其它地方）。然而，这将不可避免地导致跨材料污染和材料混合物的形成，其行为仍然不确定，需要进一步调查。本文简要讨论了ITER设计中仍然存在争议的一些最突出的等离子体与壁相互作用问题，以及通过研发或设计变更和/或专门的操作规定解决这些问题的前景。它们包括：（i）I型ELM和中断期间的等离子体热负荷和材料损坏，以及缓解的前景，（ii）碳膜中共沉积氚存量的控制，（iii）混合材料的影响，以及（iv）使用钨等离子体面对部件的等离子体操作。未来研究的方向和重点提出了缩小剩余的不确定性，提高在这些领域的解决方案的信心。
Designing the interface between a thermonuclear plasma and the solid material environment is arguably one of the highest technical challenges of ITER and of the successful development of future fusion power reactors. Carbon-based materials are recognized to have superior thermomechanical properties and do not melt, but they retain high levels of tritium by co-deposition with eroded carbon that could severely constrain plasma operations. A carbon-fibre-composite (CFC) divertor target in ITER would survive long enough only with methods of mitigation/suppression of large edge localised modes (ELMs). Metallic materials, such as tungsten, would avoid the tritium retention issue, but melt layer losses due to large ELMs and disruptions may lead to severe damage and unacceptably short lifetimes. Maintaining plasma purity with high-Z materials remains a concern. A mix of several different plasma-facing materials is proposed in ITER to optimize the requirements of areas with different power and particle flux characteristics (i.e., Be for the first wall, CFC for the divertor strike point tiles and W elsewhere in the divertor). However, this will inevitably lead to cross-material contamination and the formation of material mixtures, whose behaviour remains uncertain and requires further investigation. Some of the most outstanding plasma–wall interaction problems that are still at issue in the design of ITER are briefly discussed in this paper, together with prospects for their resolution, by either R&D or design changes and/or dedicated operation provisions. They include: (i) plasma thermal loads and material damage during type I ELMs and disruptions, and prospects for mitigation, (ii) control of co-deposited tritium inventory in the carbon films, (iii) effects of mixed-materials and (iv) plasma operation with tungsten plasma-facing components. Directions and priorities of future research are proposed to narrow the remaining uncertainties and improve confidence in solutions in these areas.