Radiative transfer through carbon ablation layers

Abstract

The composition, emittance, and transmittance of carbon plasmas have been calculated for temperatures of 3000 and 5000°K, thicknesses from 0.01 to 1.0 cm, and pressures from 0.1 to 10.0 atmospheres. The carbon plasmas are assumed to be isothermal and in local thermodynamic equilibrium. The radiation includes molecular bands, atomic lines, and continuum processes. The calculations consider molecular carbon molecules, atomic and singly ionized carbon atoms, and electrons. The emittance and transmittance results are applied to a simple model of the ablation layer in the stagnation shock layer for two cases: (1) Jupiter entry and (2) Earth entry. The results show that the molecular carbon bands are most effective in blocking the high-energy stagnation shock layer radiation when the ablation shock-layer temperature is low. For high ablation-layer temperatures, the photoionization process in atomic carbon becomes very effective in reducing the radiation to the vehicle.