Spectroscopic Measurements of Microwave-discharged CO₂ Plasma for Mars Entry Conditions

抄録

Recently, various unmanned and manned Mars exploration programs have been proposed. To send a space vehicle safely to the ground of Mars, the vehicle needs to be protected from the aerodynamic heating. The accurate prediction of the aerodynamic heating is important for the design of safe and light-weight thermal protection system. For the accurate prediction, it is necessary to simulate the plasma generated behind the shock wave and to clarify its internal state. To investigate the state of the plasma, spectroscopic measurement is useful. We performed the spectroscopic measurements of carbon dioxide (CO₂) plasma generated using microwave discharge under the pressure condition during Mars entry. To investigate the basic characteristics of microwave-discharged CO₂ plasma, the spectra of the radiation were obtained in the wavelength region of 200 to 800 nm. As a result, carbon monoxide (CO) fourth positive bands, CO third positive bands, CO Ångström bands, and atomic oxygen lines were observed. Electronic excitation temperature was also estimated by the Boltzmann plot method for the atomic oxygen lines.