Analysis of chemical nonequilibrium and elemental demixing within carbon dioxide plasma flows for mars entry application

A detailed analysis of carbon dioxide plasma flows produced within the torch of the VKI plasmatron is presented. Several torch operating pressures ranging from 20 kPa up to 40 kPa have been investigated to assess their influence on the flow behavior. Two models for the description of the flow chemistry have been used : the chemical non equilibrium model and the local thermodynamic equilibrium model with variable elemental fraction. As pressure increases, the equilibrium results approach the nonequilibrium ones showing that, for the purpose of determining catalytic properties of thermal protection materials to be used during Mars planetary entry, a lighter but accurate formalism can be used.