Observation of excitation discharge instability induced by shock wave in transversely excited atmospheric gas laser

摘要

Influences of shock waves with Mach number of 1.1-1.35 on excitation discharge in transversely excited atmospheric gas laser have been investigated eliminating the other factors. The shock waves are produced by using a shock tube with the gas mixture of helium and argon. The schlieren photographs of shock wave and direct images of light emitted from the discharge are recorded simultaneously by a streak camera. It is found that the discharge does not collapse with the shock wave of 1.1 in Mach number. The shock waves at Mach number above 1.2 tend to collapse the glow discharge in spite of no halogen gas. If the shock wave does not reach to the center of the electrode, glow discharge occurs only in front of the shock wave. Even if the shock wave passes through the center of the electrode, the glow discharge occurs, however, the discharge concentrates in the tight space between the shock front and the edge of electrode. A streamer exists in the shock front when the shock wave just reaches the edge of electrode. It becomes clear that the discharge characteristics depend on the Mach number of shock wave and the position of shock wave.