Speaker
Description
Thermal Protection Systems (TPSs) of space vehicles must withstand extreme thermal fluxes and high temperatures during atmospheric re-entry, making emissivity one of the key parameters to be accurately characterised. Infrared thermography, combined with complementary diagnostics such as pyrometers and thermocouples, enables emissivity characterisation of TPS materials when heated under controlled conditions in high-temperature furnaces. Moreover, thermographic measurements performed during hypersonic Plasma Wind Tunnel testing allow the simultaneous investigation of temperature and emissivity in environments representative of atmospheric re-entry conditions. However, the practical application of radiometric thermography is often affected by significant challenges. Emissivity varies with material properties, wavelength, temperature, and surface condition, introducing substantial uncertainty in the conversion of radiance maps into reliable temperature distributions. This issue is particularly critical for innovative TPS materials, for which emissivity may not be known a priori. To overcome these limitations, this work also investigates a free emissivity thermography technique applied to infrared thermographic systems, enabling temperature determination. The results demonstrate the practical viability of free emissivity thermography for accurate radiometric temperature measurements and for the simultaneous reconstruction of two-dimensional temperature and spectral emissivity maps, supporting the qualification of space materials under re-entry-relevant conditions.
