Radiative properties of alumina particles in exhaust plume

The effect of different phase states of Al₂O₃ particles on their optical properties was analyzed when the particles flowed and were cooled in exhaust plume. The influence of three phase states (liquid, γ phase, α phase) on the image part of complex refractive index was particularly investigated in the solidification process. Different mechanisms which were responsible for the Al₂O₃ particles radiation were considered in the spectral range from ultraviolet to near infrared region. Based on the model for calculating absorption coefficient of Al₂O₃ particles in different phases deduced from Drude model, the model for calculating ultraviolet and visible radiative properties of particles with phase transition was built up. Calculation results show satisfactory agreement with experimental data. Based on the model, the influence of temperature and wavelength on radiative properties during the phase transition of A1₂O₃ particles was analyzed too.