Development of the in-situ calibration method for ITER divertor IR thermography

Takeuchi, Masaki; Sugie, Tatsuo; Takeyama, Shigeharu; Itami, Kiyoshi

In ITER divertor IR thermography, the in-situ calibration of emissivity on the divertor targets is important because emissivity will change due to changes in surface properties. Therefore, the laboratory experiment for the development of the in-situ calibration method by using an IR laser with the wavelength of 3.2 m was performed. The emissivity of the tungsten samples with the surface roughness of 0.3-5.9 m did not have strong dependence on both the wavelength in 3-5 m and the temperature in 400-1000 C. As the surface roughness was smaller, the angle profile of the scattered light of IR laser became to be peaked at the angle of the IR camera. The derivation of the emissivity from the scattered light of the IR laser is under investigation. In order to clarify the effect of plasma to the surface condition of the tungsten, the experiment for the development of the in-situ calibration method in the Large Helical Device will be planed.