Expansion Dynamics After Laser-Induced Cavitation in Liquid Tin Microdroplets

TL;DR

This study investigates how 15-ps laser pulses cause cavitation and expansion in liquid tin microdroplets, combining experiments and modeling to understand fragmentation and mass distribution relevant for EUV nanolithography.

Contribution

It introduces a combined experimental and fluid dynamic modeling approach to analyze cavitation-driven expansion and fragmentation of liquid tin microdroplets.

Findings

Good agreement between model and experiments across droplet sizes and laser energies.

Initial expansion velocity follows a power-law dependence on experimental parameters.

Late-time mass distributions are governed by a single parameter.

Abstract

The cavitation-driven expansion dynamics of liquid tin microdroplets is investigated, set in motion by the ablative impact of a 15-ps laser pulse. We combine high-resolution stroboscopic shadowgraphy with an intuitive fluid dynamic model that includes the onset of fragmentation, and find good agreement between model and experimental data for two different droplet sizes over a wide range of laser pulse energies. The dependence of the initial expansion velocity on these experimental parameters is heuristically captured in a single power law. Further, the obtained late-time mass distributions are shown to be governed by a single parameter. These studies are performed under conditions relevant for plasma light sources for extreme-ultraviolet nanolithography.