Laser shock processing of materials: experimental study of breakdown plasma effects at the surface of confining water

摘要

Abstract: Laser Shock Processing in water confinement regime was investigated for an incident 25 - 30 ns/40 J/$lambda $EQ 1.064 $mu@m laser beam. The experimental measurement of the transmission of the parasitic plasma breakdown at the surface of water confining has been performed with continuous Argon laser probe. Above 6 GW/cm$+2$/, the critical electronic density for the incident laser wavelength is achieved in the plasma by cascade ionization. Above 10 GW/cm$+2$/, it has been shown that the power density transmitted through the plasma is limited at 10 GW/cm$+2$/. The laser pulse transmitted through the breakdown plasma corresponds to the part of incident laser pulse preceding the transmission cut-off. Results are in good agreement with those obtained previously.!8