Impact of Liquid Medium on Laser Ablation Mechanism: Surface Heating and Cooling

Stainless steel target was ablated under both of Hexane and water to examine the effect of liquid on the ablation mechanism in terms of surface heating and cooling. Experimentally, a narrow, a smooth and a deep ablation is observed under water. In addition, the pit due to the collapse of cavitation bubble under water is insignificant as compared with Hexane. The focused beam on the target under liquid was estimated from measuring the crater’s diameter from the optical image. The difference in focused beam sizes is attributed mainly to the refractive index of the liquid. Heat transfer equation is solved to estimate the temperature profile on the solid surface for a single pulse. By considering the estimated beam size under liquid, the solution of heat transfer equation suggests for the first time rapid heating of the target under water, but doesn’t confirm the rapid cooling rate under Hexane. The smooth ablation in water is attributed to the more confined plasma.