Megahertz pulse-burst laser and visualization of shock-wave/boundary-layerinteraction

The development and application of a Nd:YAG pulse-hurst laser system, which is capable of operating at up to 1-MHz pulse repetition rate with high pul se energy and narrow spectral linewidth, is presented. The laser system can generate a burst of from 1 to 99 pulses over a maximum time interval of 10 0 mu s. The average single pulse energy at 1.06-1 mu is 10 mJ. This laser i s paired with a new megahertz rate charge-coupled device framing camera to obtain images of a Mach 2.5 flow over a 14-deg angle wedge at a 500-kHz rep etition rate. The sequential images clearly show the dynamic interaction be tween the incoming turbulent boundary layer and the unsteady oblique shock wave.