Dual two-color method: A new concept of ultra-wide temperature range thermography (200-3600 °C) for ITER divertor infrared thermography.

A new temperature measurement method-the dual two-color method-was developed to accurately measure the temperature over an ultra-wide temperature range (200-3600 °C) for ITER divertor infrared thermography. This novel method introduces a third wavelength filter to the conventional two-color method by replacing the shorter single wavelength bandpass filter with a customized dual-bandpass filter having two transmission bands, without having to add a third infrared camera. The dominant wavelength band of the total radiance through the dual-band filter changes automatically as the temperature increases and, consequently, either the shorter or longer wavelength band of the dual-bandpass filter is used to establish the two-color combination at both low and high temperatures.

Error estimations of the heat flux reconstruction for ITER divertor infrared thermography.

This study developed a new heat flux reconstruction code based on the dual reciprocity boundary element method for the International Thermonuclear Experimental Reactor (ITER) divertor infrared (IR) thermography system. To use divertor heat flux reconstruction in ITER, we modeled the boundary condition between the coolant pipe inner wall and the coolant based on the temperature-dependent heat transfer coefficient and also considered the temperature dependence of tungsten thermal properties. Using this reconstruction code, we evaluated the sensitivity of the input data errors, divertor coolant temperature, and surface temperature errors on the accuracy of heat flux reconstruction by using simplified heat flux profiles, which are spatially uniform on the top surface of the monoblocks.