The mechanism of radiative transfer in an argon and xenon plasma at a shock front

Experiments were conducted in a high-enthalphy shock tube to investigate radiation behind the shock front in argon at a Mach number of 16 and an initial pressure of 50 torr. Bright argon lines were observed on the background of the continuum, which is evidence for the transparence of the plasma; the self-absorption of the argon lines was also investigated. The results are interpreted on the basis of a model of luminescence delay, according to which the edges of the front exhibit faint self-luminescence and are transparent to the light flux from the central regions of the wave.