NON-ISOTHERMAL TEMPERATURE DISTRIBUTION AND RESULTING EMISSIVITY CORRECTIONS FOR THE HIGH TEMPERATURE BLACKBODY BB3200

摘要

A pyrometer operating at an effective wavelength around 650 nm was used to measure the temperature distribution along the cavity walls of a pyrolytic graphite high temperature blackbody radiator in the temperature range from 1337 K up to 3200 K. The true temperature gradient along the cavity walls was extracted applying a ray tracing Monte-Carlo simulation. The obtained temperature variations along the cylindrical cavity wall were as high as some hundred Kelvin. These extracted temperature distributions were used as input for an effective emissivity calculation, and effective emissivities of the blackbody at various wavelengths and for different temperatures are presented. These results enable a correction of absolute radiometric temperature measurements of the cavity temperature with narrow-band interference filter radiometers.