Droplet deformation and fragmentation by ultra-short laser pulses

TL;DR

This study investigates how ultra-short laser pulses cause liquid metal droplets to deform and fragment, revealing a unique asymmetric expansion and complex shape transformation driven by shockwave propagation.

Contribution

It provides the first detailed experimental analysis of droplet behavior under picosecond laser irradiation, highlighting differences from nanosecond pulse effects.

Findings

Droplets undergo asymmetric expansion and complex shape transformation.

Fragmentation occurs after rapid deformation due to shockwave effects.

Behavior differs significantly from nanosecond laser pulse impacts.

Abstract

We report on the experimental studies of the deformation and fragmentation of liquid metal droplets by picosecond and subpicosecond laser pulses. The experiments were performed with laser irradiance varying in 10E13-10E15 W/cm^2 range. The observed evolution of the droplet shape upon the impact dramatically differs from the previously reported for nanosecond laser pulses. Instead of flattening the droplet undergoes rapid asymmetric expansion and transforms into a complex shape which can be interpreted as two conjunct spheroid shells and finally fragments. We explain the described hydrodynamic response to the ultra-short impact as a result of the propagation of the laser-induced convergent shockwave through the volume of droplet.