Modeling the Transition from Ultrafast Laser Plasma Generation to Thermally Induced Bubble Nucleatio

Ultrafast laser pulses in water generate localized plasma that deposits energy on femtosecond timescales, leading to extreme temperatures, pressures, and free electron densities. This rapid energy deposition establishes steep thermal gradients and initiates complex fluid and phase transition dynamics, yet the mechanism connecting plasma formation to bubble nucleation remains poorly understood.

We present a sequential modeling framework to explore this transition. A plasma model, based on a 1064 nm wavelength and 15 fs pulse duration, reveals the thermodynamic properties of water following energy deposition. Simulations predict a confined plasma region approximately 30 microns in diameter, with peak temperatures exceeding 1500 K, pressures surpassing 100 MPa, and electron densities on the order of 10²¹ cm^-3. These outputs serve as boundary conditions for a thermal modeling incorporating one-dimensional heat conduction, latent heat effects, and superheating thresholds. The resulting temperature fields are then used to evaluate the onset of phase transition without assuming a predefined nucleation pathway.

Our model framework allows evaluation of both homogeneous and heterogeneous boiling scenarios, depending on local thermodynamic conditions. While further refinement is underway-particularly in initializing the fluid response and tracking the interface. This approach establishes a foundation for connecting ultrafast laser-soft matter interaction to early-stage vapor formation.