Title: A comprehensive screening of plasma-facing materials for nuclear fusion Show Chinese title

Title: 面向核聚变的等离子体材料的全面筛选

Abstract: Plasma-facing materials (PFMs) represent one of the most significant challenges for the design of future nuclear fusion reactors. Inside the reactor, the divertor will experience the harshest material environment: intense bombardment of neutrons and plasma particles coupled with large and intermittent heat fluxes. The material designated to cover this role in ITER is tungsten (W). While no other materials have shown the potential to match the properties of W, many drawbacks associated with its application remain, including: cracking and erosion induced by a low recrystallization temperature combined with a high ductile-brittle transition temperature and neutron-initiated embrittlement; surface morphology changes (fuzz layer) due to plasma-W interaction with subsequent risk of spontaneous material melting and delamination; low oxidation resistance. This work aims to produce a structured and comprehensive materials screening of PFMs candidates based on known inorganic materials. The methodology applied in this study to identify the most promising PFM candidates combines peer-reviewed data present in the Pauling File database and DFT calculations of two key PFMs defects, namely the surface binding energy and the formation energy of a hydrogen interstitial. The crystal structures and their related properties, extracted from the Pauling File, are ranked according to the heat-balance equation of a PFM subject to the heat loads in the divertor region of an ITER-like tokamak. The materials satisfying the requirements are critically compared with the state-of-the-art literature, defining an optimal subset where to perform the first-principles electronic structure calculations. The majority of previously known PFMs are captured by this screening process, confirming its reliability. Additionally, less familiar refractory materials suggest performance that calls for further investigations. Show Chinese abstract

Abstract: 等离子体面对材料（PFMs）是未来核聚变反应堆设计中最具挑战性的课题之一。 在反应堆内部，偏滤器将经历最严酷的材料环境：中子和等离子体粒子的强烈轰击，以及大而间歇的热通量。 ITER中指定用于此作用的材料是钨（W）。 虽然没有其他材料显示出能够与W的性能相媲美的潜力，但其应用仍存在许多缺点，包括：低再结晶温度与高延脆转变温度相结合引起的裂纹和侵蚀，以及中子引发的脆化；由于等离子体-W相互作用导致的表面形貌变化（绒毛层），随后有自发材料熔化和剥离的风险；抗氧化性差。 本工作旨在基于已知的无机材料，对PFM候选材料进行结构化和全面的筛选。 本研究中采用的方法，结合了发表在Pauling文件数据库中的同行评审数据以及两种关键PFM缺陷的密度泛函理论（DFT）计算，即表面结合能和氢间隙形成能。 从Pauling文件中提取的晶体结构及其相关性质，根据受ITER类似托卡马克偏滤器区域热负荷的PFM的热平衡方程进行排序。 满足要求的材料与最新文献进行批判性比较，定义一个最优子集以进行第一性原理电子结构计算。 大多数以前已知的PFMs都被此筛选过程所涵盖，证实了其可靠性。 此外，一些不太熟悉的难熔材料表现出需要进一步研究的性能。