Ionic strength-driven cavitation nucleation: from energy deposition-based to tension-based cavitation

TL;DR

This study demonstrates that ionic strength is the key factor controlling cavitation inception and intensity in aqueous electrolyte solutions, regardless of whether cavitation is initiated by laser energy deposition or tensile stress, through combined experiments and simulations.

Contribution

It provides a unified understanding of cavitation mechanisms driven by ionic strength, bridging energy deposition and tension-based cavitation models with experimental and simulation evidence.

Findings

Ionic strength lowers cavitation threshold in laser experiments.

Ionic strength influences seed electron generation and hydration network perturbation.

Cavitation characteristics are governed primarily by ionic strength, independent of ion species.

Abstract

In this work, we present a unified experimental and simulation investigation of cavitation in aqueous electrolyte solutions, combining nanosecond laser-induced optical breakdown and all-atom molecular dynamics (MD) simulations under tensile stress. Across both cavitation scenarios, we find that cavitation inception and intensity (bubble nucleation count, cavitation-zone length, vapor-volume fraction) are governed by ionic strength alone, with negligible dependence on the ion species. In laser experiments, increasing ionic strength lowers the breakdown threshold and amplifies bubble generation by supplying extra seed electrons for inverse Bremsstrahlung-driven avalanche ionization. We elucidate the mechanism of action of the ionic strength through the MD simulations, which essentially quantifies the net charge density in the bulk, and thus its combined influence on the generation of seed electrons and the perturbation of the hydration network. These findings identify ionic strength serving as a unifying parameter controlling cavitation in electrolyte solutions: whether driven by rapid energy deposition or by tensile stress imposed.