Thermal conductivity degradation and recovery in ion beam damaged tungsten at different temperature

• Published in: Journal of nuclear materials Vol. 511; pp. 141 - 147
• Main Authors: Cui, Shuang, Doerner, Russ P., Simmonds, Michael J., Xu, Chuan, Wang, Yongqiang, Dechaumphai, Edward, Fu, Engang, Tynan, George R., Chen, Renkun
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.12.2018; Elsevier BV
• Subjects: Defect annealing; Deuterium; Dynamic annealing; Fusion reactors; Heat conductivity; Heat transfer; Heavy ions; Ion beams; Ion irradiation; Ions; Irradiation; Materials selection; Radiation; Radiation damage; Radiation dosage; Radiation effects; Reactors; Recombination; Recovery; Temperature; Temperature dependence; Temperature effects; Thermal conductivity; Thermal management; Tungsten
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2018.09.002

Studying the effects of radiation damage on tungsten (W), a primary candidate material for plasma facing components (PFCs), is of great significance in the thermal management of future fusion reactors. Investigation of accumulation and annihilation of radiation defects under ion irradiation in tungsten offers insights in selecting operational conditions in future fusion reactor designs. Here we investigate the dosage and irradiation temperature dependence on thermal conductivity (κ) of W under fusion-relevant radiation conditions by using an improved 3ω technique. Our results show a significant reduction in κ for W irradiated at room temperature with energetic (MeV) heavy ions. The damage, quantified by displacement per atom (dpa), spanned from 10−3 to 0.6 dpa for Cu ions and 0.2 dpa for W ions. With increasing Cu ion damage level, κ decreased and reached a minimum of 52 ± 13.6 W/m·K at 0.6 dpa, ∼30% of κ for pristine W. When the ion irradiation was performed at 1000 K, which is a temperature that is sufficiently high to induce significant dynamic annealing in W, κ was largely recovered to around 80% of the pristine value. We attribute this κ recovery to the thermal annealing and annihilation of the irradiation induced defects, i.e. through vacancy/self-interstitial atom (SIA) recombination. This finding is consistent with our prior observation of defect recovery probed by deuterium retention. [Display omitted] •The thermal conductivity (κ) of W decreased significantly upon the irradiation damage of Cu or W ions at room temperature.•The κ further decreased with increasing the damage level and reached a plateau of ∼ 1/3 of the pristine W value above 0.2 dpa.•W irradiated at 1000 K reveals a largely recovered κ to ∼ 80% of the pristine value by annealing out most vacancy defects.