Large Area Black Body Source for ITER ECE In Situ Calibration*

Here we report on the development of a prototype hot calibration source for the ITER ECE system. The source is intended to meet the requirements described in DDD55 Overview of Diagnostics. The requirement is for two \textit{200 mm} diameter sources, one operating at atmospheric pressure and the other operating in vacuum near the plasma. Both will operate at temperatures up to \textit{800 $^{\circ}$C} and have an emissivity $>0.7$ for frequencies greater than \textit{120 GHz}. A realistic thermal model of a SiC hot calibration source with a surface of pyramids has been constructed. The model results will be compared with data from a prototype SiC source. The microwave emissivity of a full size (\textit{200 mm} OD) source was measured in the range \textit{100-500 GHz} with a calibrated Michelson radiometer. Heating methods under consideration will be discussed..