Investigation of pulse length’s effect on direct laser ablation and shock generation at Intensity of 10¹⁵ Wcm^-2

A significant threat for exo-atmospheric objects is thermomechanical shock via x-ray irradiation. Utilizing direct laser-driven ablation as a surrogate, simulations and experimental data show a direct relationship between the laser pulse length and ablation plasma properties and shock generation. Experiments were carried out at the OMEGA-EP Laser Facility at the Laboratory for Laser Energetics (LLE) at the University of Rochester where 3-layer targets of Silicon (50mm), Copper (25mm) and Quartz (500mm) were irradiated at a fixed total intensity of 10¹⁵ Wcm^-2 with varying pulse lengths of 100ps, 500ps, 1ns and 10ns duration. In this study, we experimentally observed that the generated shock velocities increase with the laser pulse length. Further, we observed increases in the ablation plasma scale length, electron temperature and ablation pressure with increasing laser pulse length. A comparison with 2D radiation-hydrodynamic simulations will be presented.