Precursor vacuum-ultraviolet radiation ahead of strong shock waves in a shock tube

Abstract

The profile and excitation mechanism of vacuum-ultraviolet radiation emitted from shock wave is investigated in a shock tube. For shock wave in argon, the rdiation is due to resonant transition excited by argon-argon collision in the shock front with excitation cross section coefficientS *=1.0×10−17 cm2·ev−1 and activation energyE *=11.4 ev. For shock wave in air the radition is emitted from a very thin shock layer in which the mechanism ofX 1∑→b 1∑ of N2 is excited with excitation cross sectionQ=2×10−16cm2 and activation energyE *=12.1 ev.