Research on the mechanism of emissivity enhancement by the structure of the blackbody cavity

Abstract The spaceborne blackbody with high emissivity can provide accurate infrared radiation to calibrate infrared payloads. To meet the need for improving the accuracy of infrared value traceability, this paper investigates the mechanism of enhancing emissivity through the structure of the blackbody cavity. The directional emissivity calculation based on Monte Carlo optical simulation was carried out. The normal and directional emissivity distributions of cylindrical cavity blackbody and trap-cavity blackbody (TCB) were simulated and compared. The emissivity of the 8–14 μm band was measured. The simulation and experimental results indicate that TCBs demonstrate better central normal emissivity and cylindrical cavity blackbodies exhibit higher variations in emissivity. The mechanism of high emissivity for two types of blackbodies by controlling the number and direction of light reflection is analyzed. Furthermore, we propose a blackbody design method with high-level emissivity by investigating the influence of cavity structure and reflection characteristics on blackbody emissivity, which has a high normal emissivity of 0.9997 and small variations in directional emissivity of 0.0002. The study provides theoretical and experimental support for the development of large aperture high emissivity spaceborne blackbody.