Characterization of laser-induced shock waves in aluminum under a confined liquid medium

This study presents a comprehensive comparative investigation of nanosecond laser-induced shock waves (LISWs) generated on an aluminum target under air and water confinement regimes. The spatiotemporal evolution of shock waves (SWs) was systematically characterized using the optical beam deflection technique with subnanosecond temporal resolution. LISW propagation exhibited significantly enhanced dynamics, achieving velocities of 2.5 km/s and pressures of 35 MPa in a confined medium. These values correspond to 1.67-fold and 2.69-fold increases in velocity and pressure, respectively, relative to air confinement conditions (1.5 km/s, 13 MPa) under identical fluence conditions. These experimental results demonstrate that enhancements in SW dynamics are attributed to water's superior plasma confinement capability and higher energy coupling efficiency. Theoretical modeling of SW expansion exhibited excellent agreement with the experimental data, validating the observed confinement effects. Furthermore, morphological analysis reveals that water confinement produces more uniform ablation craters with reduced thermal effects and significantly improved ablation efficiency compared to air environments. Specifically, water confinement yields 58% greater ablation at equivalent fluences, demonstrating its advantages for precision material processing. These findings will provide critical insights for optimizing laser-based material processing techniques, particularly for applications requiring controlled SW propagation and enhanced material removal efficiency.