Thermal response of nanostructured tungsten

The thermal response of nanostructured tungsten, which was fabricated in the linear divertor simulator NAGDIS-II, was investigated using pulsed plasma in the MAGNUM-PSI device and by using high powered laser pulses. The temperature evolution in response to the pulses was measured with an infrared fast framing camera. The temperature increase in response to the pulses on the nanostructured sample was significantly greater than that of the pristine sample both for plasma and laser pulses. After the pulsed plasma/laser irradiation, the nanostructured surface was observed to have melted although the measured surface temperature was much less than the melting temperature. The mechanism to account for the difference in the temporal evolution of temperature between the nanostructured and pristine samples is discussed. It is suggested that there are thermally isolated part on the nanostructures and anomalous temperature increase and melting have occurred locally on them. The amount of vapourized tungsten in response to type-I edge localized mode in ITER is discussed based on experimental observation.