Measurement of High Temperatures in the DLR Solar Furnace by UV-B Detection

The correct selection of the operating wavelength is essential for a precise pyrometric temperature measurement on solar irradiated samples, as the measurement may be disturbed by reflected solar radiation. Atmospheric conditions and particularly the material emissivity have an impact on these measurements. As an approach to solve this problem, we developed a new system that uses the UV-B wavelength range for pyrometry. Simulations and measurements on blackbodies and on real hot bodies heated in the DLR Solar Furnace specified the final measurement wavelength to be in the range of 280–292 nm. A sensitive monochromator system for this UV-B pyrometry was developed and experimentally tested. Measurements in the range of 1320-1500°C on a blackbody without solar irradiation and measurements from 1500°C to about 2400°C on a real solar heated sample are presented and discussed. Final calibration was performed by using blackbody radiation of 1500°C. Two calculation methods are compared. The influence of the calibration temperature on the quality of the measurement is shown. In this first approach, the resolution of the system turned out to be in the order of magnitude of 1 K and the accuracy in the order of magnitude of 10 K.