Early dynamics of cavitation bubbles generated during ns laser ablation of submerged targets

Abstract

In this study, we observe and study the early evolution of cavitation bubbles generated during pulsed laser ablation of titanium targets in different liquid environments utilizing a high-resolution stroboscopic shadowgraphy system. A hydrodynamic model is proposed to calculate the early pressure changes within the bubble and in the surrounding fluid. Our results show that the cavitation bubble is a low-pressure region that is bounded by a high-pressure fluid lamina after the incipient stage, and its evolution is primarily affected by the liquid density. Moreover, the initial bubble pressure increases substantially in high viscosity liquids. This work illuminates how the liquid properties affect the early bubble dynamics and is a step towards a deeper understanding of laser-materials interactions in liquid environments.

Photomechanical Laser Fragmentation of IrO2 Microparticles for the Synthesis of Active and Redox‐Sensitive Colloidal Nanoclusters

“…In fact, similar studies of the shockwave propagation upon laser ablation in liquid show no significant shockwave velocity decrease within the first few tens to hundreds of ns after pulse impact. [47,48] At Δt = 50 ns, an area of decreased reflectivity is visible surrounding the MP. This area increases up to Δt = 5 µs and is attributed to the formation and propagation of a cavitation bubble.…”

“…[55] As the supercritical liquid is the precursor for the cavitation bubble, [11] another possible route of estimating the pressure of the supercritical water is to consider the cavitation bubble dynamics. The pressure p B within the cavitation bubble can be estimated by the following equation [47]…”

Cavitation erosion by shockwave self-focusing of a single bubble

“…a solid or fluid boundary. Recently, the dynamics of a bubble at closest distance to a solid boundary have gained attention in experimental studies [98] , [99] , [67] , [68] . Cavitation bubbles at interfaces in general develop non-spherical dynamics and can produce fast and microscopic flows.…”

Time resolved studies reveal the origin of the unparalleled high efficiency of one nanosecond laser ablation in liquids

“…The simultaneous expansion of the cavitation bubble and shockwave explains the observation of Mach cones at early stages (50 fs pulse width, 1.58 J/cm 2 41 , 8 ns pulse width 43 , 13 ns pulse width 44 ). In the literature, for the ablation of Ti with a fluence of 68.5 J/cm², the detachment of the shockwave from the bubble is observed between a delay time of 20-52 ns 45 and between 6-27 ns at 29.8 J/cm 2 46 . Further investigations using shadowgraphy show the difference in the temporal evolution of ablation of epoxyresin in air and in water for delay times >10 ns 47 .…”