The early transient dynamics reaction of KDP surface during nanosecond laser breakdown

The early kinetics of KDP surface after nanosecond laser induced breakdown was studied via time resolved pump and probe method. The plasma absorption region appears at the bottom of the pump laser’s rise edge, and expands continuously in the laser duration and fades after several nanoseconds. The shockwave, propagating in the air side, appears at the top of the rise edge. Its maximum velocity is in direct proportion to laser energy, achieving near the pulse peak and then decreasing rapidly. The propagation of shockwave in the free decaying phase matches well with the point explosion model.