ABOUT THE MEANING OF THE HAGEN – RUBENS RELATION TO RADIATION THERMOMETRY

Abstract − Pyrometry is the only way to obtain temperature measurements when performing fast (µs duration) experiments on metals up to and above their melting points. Converting the pyrometer signals to true temperatures requires some knowledge about the normal spectral emissivity of the target at the operating wavelength of the pyrometer. Because dynamic emissivity measurements are rather difficult, one often has to resort to assumptions about the temperature and wavelength dependence of emissivity instead of a direct measurement. The HAGEN–RUBENS relation between the normal spectral emissivity of a metal and its electrical resistivity can be helpful in making such assumptions. In this work, a method for obtaining good estimates of the normal spectral emissivity of metals and alloys above their melting points as a function of temperature, based on the HAGEN-RUBENS relation, is presented. Its usefulness is examined by comparing results derived from it to actual emissivity data on several liquid metals and alloys that were measured using a pulse-heating technique