High Transient-Thermal-Shock Resistant Nanochannel Tungsten Films.

Tao Cheng,Changzhong Jiang,Guangxu Cai,Feng Ren,Shijian Zhang,Wenjing Qin,Xiang Liu,Youyun Lian,Xiaoyun Le,Jun Tang

doi:10.3390/nano11102663

Abstract

Developing high-performance tungsten plasma-facing materials for fusion reactors is an urgent task. In this paper, novel nanochannel structural W films prepared by magnetron sputtering deposition were irradiated using a high-power pulsed electron beam or ion beam to study their edge-localized modes, such as transient thermal shock resistance. Under electron beam irradiation, a 1 μm thick nanochannel W film with 150 watt power showed a higher absorbed power density related cracking threshold (0.28–0.43 GW/m2) than the commercial bulk W (0.16–0.28 GW/m2) at room temperature. With ion beam irradiation with an energy density of 1 J/cm2 for different pulses, the bulk W displayed many large cracks with the increase of pulse number, while only micro-crack networks with a width of tens of nanometers were found in the nanochannel W film. For the mechanism of the high resistance of nanochannel W films to transient thermal shock, a residual stress analysis was made by Grazing-incidence X-ray diffraction (GIXRD), and the results showed that the irradiated nanochannel W films had a much lower stress than that of the irradiated bulk W, which indicates that the nanochannel structure can release more stress, due to its special nanochannel structure and ability for the annihilation of irradiation induced defects.

Highlights

Nuclear fusion energy has a great potential to replace traditional energyas one of the major energy sources, due to its clean nature
The results show that the nanochannel W films have a higher absorbed power density related cracking threshold than commercial bulk W and have a lower residual stress after irradiation
Nanochannel W films were prepared by ultrahigh vacuum DC magnetron sputtering deposition and irradiated by high power pulsed electron beam and pulsed ion beam irradiation, to evaluate their performance under edge-localized modes (ELMs)-like transient thermal loads

Summary

Introduction

Nuclear fusion energy has a great potential to replace traditional energy (coal, oil, etc.)as one of the major energy sources, due to its clean nature. In the International Thermonuclear Experimental Reactor (ITER), besides high H, He, and neutron fluxes, plasma-facing materials (PFMs) have to withstand a quasi-stationary heat flux load of 10 MW/m2 during normal operation, a slow transient heat load of up to 20 MW/m2 , and transient thermal loads of 1 GW/m2 under transient events, such as Type I edge-localized modes (ELMs), plasma disruption, and vertical displacement modes (VDE) [1,2,3,4] These events have different pulse durations and energy release ranges, which can play a major role in the erosion rate and the PFM lifetime. Large pulsed thermal loads will cause severe damage to PFMs, such as plastic deformations, cracking, melting, and even creep [6,7,8,9,10]

Methods

Results

Conclusion