Radiative Characteristics of Carbonaceous Ablation Layers with Reflection Effects

Abstract

The equilibrium composition and spectral absorption coefficient of SiC ablation layer plasmas have been calculated for temperature of 5000 to 7000 K, layer thickness of 0 to 7.5 mm, and pressure of 0.1 to 1.0 MPa. The radiations included were molecular bands, atomic lines, and continuum processes. The absorption coefficient thus calculated was applied to a simplified shock layer model for the Jupiter entry probe to investigate the effectiveness of the ablation layer in reducing the radiative heating from a shock layer to a body surface. It was found that the SiC ablation layer is very effective to protect the body from radiative heating and that the photoionization processes of atomic carbon and silicon were mainly responsible for radiative absorption at high photon energy range. Furthermore the molecular carbon bands were effectively absorptive in relatively low photon energy range, Particularly at low temperatures.