Research on the normal spectral band emissivity of tungsten between 150 and 500 °C

Tungsten is the baseline divertor material for a tokamak. Due to the effect of the interaction of plasma and the first wall, the first wall accumulates a large amount of heat flux and suffers irreversible damages. Therefore, the diagnosis of the first wall temperature of the tokamak by using a radiation thermometer is the premise to ensure the safe and stable operation of the whole facility. However, in order to achieve high precision of temperature measurement, the emissivity of tungsten must be measured accurately. In this paper, we built a set of emissivity measurement system and a method for accurate calculation of emissivity is proposed. This method effectively eliminated the interference of background radiation and improves the accuracy of emissivity measurement. By using this method, the author measured the emissivity of tungsten under the conditions of different surface roughness in the range of 150 °C-500 °C and discussed the uncertainty of the measurement at the end.