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

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.