Radiation effects of the laser ablative shockwaves on aluminium under atmospheric conditions

Abstract

Numerical investigation of laser induced shock wave (SW) propagation into bulk aluminium target with and without the effects of electron thermal radiation (ETR and No-ETR) is demonstrated using MULTI-fs 1D-code over intensity range 1010 - 1011 W/cm2. The radiation emitting from the plasma is observed to show negligible effects on the SW propagating into aluminium target for low energy (25 mJ) and significant effects at high energy (175 mJ) which was found to be dominant up to 50 ns of time. The observations show that two SW have been launched on to the target surface: one during the pulse duration termed as primary SW (PSW) and the other immediately after the laser pulse termination termed as secondary SW (SSW). The effects of ETR were found dominant on SSW compared to that on PSW for 175 mJ. The PSW and SSW found to coalesce at around 30-40 ns and move as a single SW after these time scales. The resultant pressure after coalesce is higher than the individual ones before coalesce for 175 mJ. The PSW pressures at 25 mJ and 175 mJ were found to be ∼1.5 GPa and ∼7 GPa, respectively that were launched at 10 ns and 7 ns.