Laser shock processing of materials: study of laser induced breakdown in water confinement regime.

摘要

Laser Shock Processing (LSP) in water confinement regime was investigated for an incident 20-25 ns/40 J/λ=1,064 μm pulsed laser beam. Experimental measurements of the shock wave temporal profiles induced by LSP have been performed with Velocimetry Interferometer System for Any Reflector (VISAR). Above 10 GW/cm2, the peak pressure is limited and the pulse pressure duration is reduced by parasistic plama occuring in the confining water. The observation of the interaction zone with fast camera shows that the breakdown at the surface of the confining water is the only phenomena limiting the efficiency of the LSP. This plasma absorbs the incident laser energy and the power density reaching the target decreases. The duration of shock wave induced in the target is then shortened. This experiment explains the current limit of LSP in water confinement mode and opens a new research field to understand the plasma effect at the surface of the confining water.