TY - JOUR KW - Energy KW - Target KW - USA KW - Surface KW - Pulse KW - Ablation KW - Laser KW - Laser ablation KW - Laser ablation KW - Time-resolved KW - Time KW - Ca KW - E KW - Plasma KW - Solids KW - C KW - Development KW - Picosecond KW - Picosecond laser KW - Picosecond laser ablation KW - Energies KW - Results KW - Ambient KW - Shock KW - Shock wave KW - Shock wave KW - Wave KW - Expansion KW - Pulse laser KW - Pulse laser ablation KW - Physics KW - Air KW - Ablation plasma KW - Interface KW - Zone AU - Samuel S Mao AU - Xianglei Mao AU - Ralph Greif AU - Richard E Russo AB -

Using picosecond time-resolved shadowgrams, we measured the development of an expanding air plasma during double picosecond pulse laser ablation of solids. Prior to the formation of the air plasma, a shock wave was established by the first laser pulse interaction with the solid target. The second picosecond laser pulse interacted with the shock wave and induced the air plasma at the interface between the shock wave front and the ambient air. After the end of the second picosecond ablation laser pulse, the temporal expansion of the air plasma was found to follow the relation r~t2/5. Results from this air plasma suggest that the shock wave induced by the first laser pulse only absorbs approximately 5% of the energy of the second picosecond laser pulse. Nevertheless, the expansion of the air plasma towards the target results in an enlarged heat-affected zone at the target surface.

AD -

Univ Calif Berkeley, Lawrence Berkeley Lab, Berkeley, CA 94720 USA

BT - Journal of Applied Physics C2 - LBNL-47393 DA - 04/2001 DO - 10.1063/1.1351870 IS - 7 LA - eng LB - Laser N2 -

Using picosecond time-resolved shadowgrams, we measured the development of an expanding air plasma during double picosecond pulse laser ablation of solids. Prior to the formation of the air plasma, a shock wave was established by the first laser pulse interaction with the solid target. The second picosecond laser pulse interacted with the shock wave and induced the air plasma at the interface between the shock wave front and the ambient air. After the end of the second picosecond ablation laser pulse, the temporal expansion of the air plasma was found to follow the relation r~t2/5. Results from this air plasma suggest that the shock wave induced by the first laser pulse only absorbs approximately 5% of the energy of the second picosecond laser pulse. Nevertheless, the expansion of the air plasma towards the target results in an enlarged heat-affected zone at the target surface.

PY - 2001 SP - 4096 EP - 4098 ST - J. Appl. Phys. T2 - Journal of Applied Physics TI - Influence of preformed shock wave on the development of picosecond laser ablation plasma VL - 89 ER -