A new experimental device to measure directional spectral emittance of semitransparent media at high temperatures

Abstract

A new experimental device to measure directional spectral emittances was developed to characterise a wide range of semitransparent media at a temperature level as high as 2100 K. A CO 2 laser beam is used as the heating source. Its energy distribution is homogenised by a square aperture kaleidoscope. The radiative heat flux emitted by the sample is measured through a radiometric technique associated with narrowband filters. The spectroradiometer is mounted on a goniometric system allowing directional measurements from 5° to 90° around the fixed sample. Experimental data from Al 2 O 3 samples, obtained by a sintering process from loose alumina powder, are presented for four wavelength values and several temperatures between 1643 K and 2093 K.