A growth/annealing equilibrium model for helium-induced nanostructure with application to ITER
A growth/annealing equilibrium model for helium-induced nanostructure with application to ITER
复制标题
氦诱导纳米结构的生长/退火平衡模型及其在 ITER 中的应用
DOI：
10.1016/j.nme.2019.01.034
复制
发表时间：
2019
影响因子：
2.6
通讯作者：
R. Pitts
中科院分区：
文献类型：
--
作者：
G. D. Temmerman;R. Doerner;R. Pitts
现在公知的是，在高温下暴露于氦（He）等离子体的情况下，钨（W）表面通过被称为“绒毛”的纤维状纳米结构的生长而被改性。当满足一组特定的条件时，W模糊的形成就会发生，并引起对ITER W偏滤器目标行为的关注。然而，关键的开放问题仍然是，无论是或不绒毛实际上会在ITER中形成。现有数据的分析表明，绒毛退火动力学可以描述的扩散类动力学定律。然后，提出了一个生长/退火平衡模型，考虑到边缘局域模式（ELM）引起的侵蚀和模糊生长和退火的瞬态温度漂移的影响。此外，绒蚀率和导热系数随厚度的增加而降低的现象也得到了一致的处理。主要的发现是，随着绒毛变厚，其热导率降低，在ELM期间达到的峰值温度增加。考虑到生长速率和退火速率之间的竞争，对于给定的ELM能量密度，存在一个平衡厚度，在该平衡厚度以上，模糊退火占主导地位。在没有ELMs的情况下，绒毛厚度将以典型的t0.5时间依赖性增加。
It is now well-known that under exposure to a helium (He) plasma at elevated temperatures, a tungsten (W) surface is modified by the growth of a fibreform nano-structure referred to as “fuzz”. Formation of W fuzz occurs when a specific set of conditions are met and raises concerns for the behaviour of the ITER W divertor targets. The key open question remains, however, of whether or not fuzz will actually form in ITER.An analysis of existing data shows that the fuzz annealing kinetics can be described by a diffusive-like kinetics law. A growth/annealing equilibrium model is then proposed to take into account Edge Localized Mode (ELM)-induced erosion and the effect of the transient temperature excursion on fuzz growth and annealing. In addition, both the decrease of fuzz erosion rate and thermal conductivity with increasing thickness are treated consistently. The main finding is that as fuzz grows thicker, its thermal conductivity decreases and peak temperature attained during an ELM increases. Given the competition between growth and annealing rates, an equilibrium thickness exists above which fuzz annealing dominates for a given ELM energy density. In the absence of ELMs, the fuzz thickness would increase with the typical t0.5time dependence.
影响因子：
3.3
作者：
Kajita, Shin;Sakaguchi, Wataru;Saeki, Tsubasa
通讯作者：
Saeki, Tsubasa