Thermal Conductivity Measurement of Fuzzy W Using a Thermoreflectance Method

Fuzzy nanostructured tungsten (W) is formed by helium (He) plasma irradiation. In fusion devices, the thermophysical properties are important to consider the response to pulsed heat load from the plasma. In this work, the thermal conductivity of the W fuzz is measured using a pulsed light heating thermoreflectance method. A detailed model was developed to explain the entire temporal evolution of the thermoreflectance signal. It was found that the thermal conductivity of the nanostructured layer was deduced to be in the range of 0.18%–0.21% of the pure (ideal) W and lower than the previously reported highly porous metallic materials. In addition to the porosity, the specific nonuniform nanofiber structure is likely to contribute to the low effective thermal conductivity.