Accuracy improvement in the source-based calibration of radiative heat flux sensors by consideration of the temperature non-uniformity of the high temperature blackbody

Abstract

We have improved the accuracy in source-based calibration of radiative heat flux sensors by considering the temperature non-uniformity of the blackbody cavity. The method measures the responsivity of a heat flux sensor as a function of distance from the blackbody aperture. From this variation of the responsivity, the temperature distribution and the effective emissivity of the blackbody can be determined via a Monte Carlo simulation. The calibration uncertainty is evaluated to be 2.3% (k = 2) for irradiance values up to 10 kW m(-2) at a blackbody temperature around 2900 degrees C. In order to verify the accuracy improvement, the results are compared with those of a detector-based calibration, which demonstrated an agreement within the uncertainty.