Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9951875 | Fusion Engineering and Design | 2018 | 7 Pages |
Abstract
Pure tungsten samples were irradiated by helium plasma in the linear plasma device PSI-2 with an ion energy of 40âeV and a flux of 1.1âÃâ1022âmâ2sâ1. The irradiation temperature was from 523âK to 773âK and the fluence was from 1.0âÃâ1025 to 1.0âÃâ1026âmâ2. A damaged layer of 10ânm thickness was formed on the sample surface with a destroyed crystalline structure. Helium-bubbles and surface modification in nanoscale were observed. Thermal conductivities of the ultra-thin damaged layers were measured by the transient thermoreflectance technique. Result shows that the thermal conductivity reduced two orders of magnitude compared to the bulk value and decreased with increasing irradiation temperature and fluence. Moreover, the helium-irradiated samples were exposed to ELM-like heat load produced by electron beam on EMS-60. The pulse length was 1âms and each sample was exposed to 5 pulses. Melting occurred under power density of 1.7âGWâmâ2. As the thermal conductivity of the damaged layer decreased, the molten bath of the irradiated sample deepened. The degraded thermal conductivity led to a lower melting threshold. The characterization of the thermal conductivity of the damaged layer induced by the plasma irradiation is a promising way to estimate the damage level, as well as the failure threshold, of the plasma facing components.
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Authors
Shilian Qu, Hao Sun, Arkadi Kreter, Yue Yuan, Long Cheng, Zhengxing Huang, Ben Xu, Wanqi Chen, Wei Cui, Zhenan Tang, Yuzhen Jia, YouYun Lian, Xiang Liu, Wei Liu,