Laser-induced cavitation bubble behavior on solid walls of different materials

Laser-induced cavitation bubble behavior on the solid walls of different materials was experimentally investigated by focusing the pulsed laser on the wall. To examine the influence of wall reflectivity on laser-induced cavitation, high-speed observations of the bubble behavior and impulsive-force measurements were carried out on aluminum, steel, copper, and acrylic resin walls. It was found that the bubble behaviors and impulsive forces vary with the wall materials, and their behaviors depend on the wall reflectivity. Increased bubble diameter, bubble collapse time, and high impulsive force were observed on the walls with high reflectivity. This result can be due to the increased laser illumination on the highly reflective walls. This promotes the heating of liquid near the wall at the laser breakdown in the first impact on the wall, while the increased bubble diameter by this effect promotes the bubble collapse phenomenon and intensive shockwave formation, resulting in the high impulsive forces on the wall in the second impact.