Determination of a thermal property of carbon layers from IR measurements in JET NBI test bed using optimisation methods

An optimisation algorithm is used to realize an automated determination of a carbon layer thermal property from IR temperature measurements. This algorithm is based on a 1D linear thermal model of the plasma facing component. It is tested on measurements from two MkIIa JET divertor tiles placed in the NBI JET test bed. Heat fluxes of 5–100 MW/m2 were applied on those tiles. The resulting surface distribution of the carbon layer is discussed, including its evolution through the experiment, and its influence on the computed surface heat loads. Heat fluxes computed from IR and thermocouple temperature measurements are compared to the previous results. First computation of heat loads during short high flux NBI pulses simulating ELMs using previously determined carbon layer properties are also presented.