An induction plasmatron application for simulation of entry into Martian atmosphere

First stage of work on surface catalycity determination of thermal protection materials (TPM) under conditions of entry into Martian atmosphere is described. Because Mars atmosphere includes CO2 as basic component (>95%), at the beginning it is advisable to focus efforts on catalycity determination in pure dissociated CO2 and later to take into account influence of small additions of N-2 (2.7%) and Ar (1.6%). Subsonic jets of pure dissociated CO2 were generated using the IPG-4 induction plasmatron. Mass flow optimization allowed to realize stable discharge without limitation in operation time in wide ranges of pressure and power. Those are limited only by capacity of exhaust system and regulation range of HF-generator' power. Heat flux measurements using water-cooled steady-state calorimeters were carried out to demonstrate catalycity effect. It was found that maximum ratio of heat fluxes to copper and molybdenum was higher than 1.5, so significant catalycity effect is observed in realized conditions. Effective probabilities of dissociated CO2 heterogeneous recombination gamma(eff) were determined for black ceramic tile and carbon-carbon material with antioxidation coating which were used in Buran's TPS. Catalycity determination was made by comparison of measured and calculated heat fluxes with calculations were made under assumption that reactions O + O --> O-2 (1) and CO + O --> CO (2) are described by Eley-Rydell model and gamma(eff) = gamma(1) = gamma(2). It was established that effective recombination probabilities of tested materials have opposite temperature trends. Obtained data are presented.