Spectroscopic investigation of an inductively heated CO2 plasma for Mars entry simulation

The principal availability of a high enthalpy ground test facility for the simulation of atmospheric entry into a martian atmosphere based on a CO2 plasma is shown. The plasma is characterized using both the heat flux and pressure probe techniques. Two different approaches to determine local enthalpies are presented. Results of the plasma characterization using Optical Emission Spectroscopy (OES) are presented and a quantitative comparison of the measurement results, with numerically simulated spectra using the PARADE database, are analysed. In order to create a data basis for further improvement and validation of radiation codes for Mars entry scenarios, emission spectroscopic measurements have been performed. The first qualitative comparison of the measurement data from the 21 MJ/kg condition with numerically created CO2 spectra has been used to identify the radiating species. Atomic oxygen and atomic carbon could clearly be identified, also there is evidence of oxygen and carbon ions. From the molecule-based radiation, C2 Swan and CO 3rd Pos. as well as the CO+ 1st. Neg. systems could be identified and showed a fairly good agreement with the PARADE data. The CO+ Comet Tail system has been added very recently in PARADE and it is shown within this paper that it contributed significantly to the measured radiation.