Pliable solid medium as a plasma confinement layer for laser peening

Laser peening is a promising surface treatment technique for enhancing the mechanical performance of metals. In laser peening, the plasma confinement layer contributes to the generation of high-pressure shockwaves by suppressing the expansion of laser-induced plasma. Therefore, the choice of a plasma confinement layer is important for improving laser peening effectiveness. For laser peening in environments where liquid materials cannot be used as a plasma confinement layer, alginate gel, which is a pliable material with shape-following capabilities, has been proposed to reduce the acoustic impedance mismatch caused by surface roughness when using solid materials. In this study, the feasibility of alginate gel as a plasma confinement layer and an appropriate process window for laser irradiation were investigated. The results of this study are then presented.