Influence of Different Constraints on the Wave Structure of the Flow Field in Laser Propulsion
Ming Wen, Yan-Ji Hong, Guang-Yu Wang, Ji-Fei Ye and Cun-Yan Cui
A lens was used to focus the CO2 laser beam and the air was brokendown. After sequential problem of the experimental system was solved effectively, wave structures of laser propulsion flow field for three different constraints were studied with a high-speed shadowing system. Sequential photographs of the development of the wave were obtained. The ignition characteristics of the laser plasma and its propagation speed of the laser-supported absorption wave, which developed into the blast wave, were analysed primarily. The results show that the flow field propagated, without any constraint, in the shape of an ellipse. Obvious reflection and diffraction of the blast wave occurred at the edges for the plate target and the 15 expanding target constraint. A slowly changing low-density and a high-pressure air mass appeared for all three constraints. When the laser-supported detonation wave developed into a blast wave, the propagation speed dropped abruptly and reached the speed of sound in about 70~80 microsecond.