Development of in-situ calibration method by using an IR laser for ITER divertor IR thermography

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

Divertor IR thermography is a diagnostic system in ITER to measure the surface temperature distribution of the divertor target. One of the issues is that the emissivity of the diverotor target can be changed due to changes in the surface condition. Therefore, in-situ calibration method is being developed in our laboratory. In the experiment, two tungsten samples of mirror and sandblasted surface were used by heating up to 280 C. The measured emissivity of the mirror surface was 0.05-0.4 and that of the sandblasted surface was 0.5-0.8 in the wavelength range of 3-5 um. When an IR laser was injected to the tungsten surface, the scattered light profile of the sandblasted surface was broad. On the other hand, that of the mirror surface was peaked around the axis of an IR camera. Thus, preliminary data of the relation between the emissivity and the scattered light for two different surface conditions was obtained. Furthermore, the recent result heated up to 1100 C will be presented.