Radiation properties of air behind strong shock wave

The problem of descent spacecrafts safety is closely related to the correct assessment of heat fluxes to their surface. This work is devoted to an experimental study of radiative heat fluxes that play an important role during the entry of a spacecraft into the Earth's atmosphere at superorbital velocity. The radiation properties of high-temperature air were measured in the detonation driven shock tube DDST-M at the gas pressure 0.25 Torr ahead of the shock wave in the shock wave velocity range from 7.7 to 11.4 km/s. The applied registration method fixates the time-integrated distribution of the radiation intensity of the shock heated air passing by the measuring cross section. The measurements were carried out in the spectral range from 190 to 1100 nm. Simultaneously, the evolution of the radiation power at certain wavelengths that are selected using monochromators was recorded. Time spectrograms at certain wave lengths make it possible to determine the effective process time that can be used to recalculate the measured integral radiation intensity to the radiation power that traditionally measures by 3-D spectroscopy method. A new spectral model is presented that performs a line-by-line calculation of the emission and absorption spectra of atoms and molecules. The experimental results are compared with the calculated data obtained using the spectral model, as well as data from other measurements.