Experimental Study of Nonequilibrium Phenomena behind Strong Shock Waves Generated in Super-orbital Reentry Flight

The nonequilibrium behavior behind the shock wave in a thin air was investigated experimentally. For the experiment, a free-piston-driven shock tube was used and a radiation from behind the shock front was investigated spectroscopically. Being based on the radiation spectrum emitted from the region behind the shock wave, the distributions for rotational and vibrational temperatures of N2 and N + 2 , and electron density were determined. These results were compared with those for a pure nitrogen gas which was investigated previously. It was found that there is remarkable resemblance between the distributions in an air and in a pure nitrogen gas. This suggests that the existence of molecular oxygen in an air has only a little in°uence on the behavior of temperatures of N2 or N + 2 , and the behavior of electron density behind the shock wave, compared with those observed in a pure nitrogen gas.