Schlieren Visualization Technique Applied to the Study of Laser-Induced Breakdown in Low Density Hypersonic Flow

Experimental results on the visualization of the time evolution of the laser-plasma induced breakdown produced in low density hypersonic flow using the Schlieren technique are presented. The plasma was generated by focusing the high power laser pulse of a CO2 TEA laser in the test section of the IEAv 0.3m Hypersonic Shock Tunnel. An ultra-high speed electronic tube camera was used to register the event. The photographs reveal the expansion of the shock wave produced by the laser generated hot plasma and the convection of the plasma kernel by the hypersonic flow. It is also observed the interaction between the plasma disturbed region and the shock established by the flow around an hemisphere-cylinder model. A strong change in the shock wave structure near the model was observed, corroborating the DEAS concept