Excitation ahead of shock fronts in krypton measured by single line laser absorption

Abstract

The number densities of the metastable 5s[1 1/2]2 state and the 5s[1 1/2]1 state of krypton ahead of shock fronts have been determined from the measured absorption of single line laser radiation. Shocks with Mach numbers from 12 to 21 were investigated at preshock pressures from 0.7 to 2.7 kPa. An exponential rise of this excitation precursor having time constants of about 8 ws is found. The metastable concentration atM = 20 is about 10 ppm. The experimental results agree within an order of magnitude with published model predictions for argon and xenon shocks.