Simulation of the Infrared Views of the Upper Port VIS/IR Imaging System of ITER

In the majority of nuclear fusion experiments equipped with carbonaceous plasma-facing components (PFCs), infrared (IR) imaging diagnostics are routinely used for monitoring the surface temperature of the PFCs exposed to high heat fluxes. However, future fusion machines, such as ITER, will be equipped with metallic PFCs. As a consequence, due to their low emissivity, the evaluation of the surface temperature will have to take into account the multiple reflections of the light coming from hot regions. In order to assess the total IR flux collected by the sensor located at the upper port VIS/IR system of ITER, realistic simulations of the IR views of the ITER tokamak have been developed using a Monte Carlo ray-tracing code (SPEOS CAA V5 Based). The simulation includes the thermal emission, the bremsstrahlung radiation, and the reflections thereof inside the real complex 3-D geometry (from CATIA) of the vessel. The IR simulated images in conditions of plasma operation are presented, and the contribution of the reflected flux for two divertor configurations (carbon fiber composite and tungsten) is analyzed. Finally, the achievable measurement accuracy on the surface temperature of the PFCs from the upper port VIS/IR imaging system is discussed.