Insight into the evolution of laser-induced plasma during successive deposition of laser energy

TL;DR

This study investigates the evolution of laser-induced plasma during successive energy depositions, revealing nonlinear absorption effects, new physical phenomena, and proposing optimal pulse intervals for practical applications.

Contribution

It provides new experimental and numerical insights into plasma behavior during successive laser pulses, including the observation of novel phenomena and a Maxwell's theory-based explanation.

Findings

Nonlinear energy absorption during successive pulses.

Observation of fourth-lobe and multiple shock waves.

Optimal pulse intervals identified for practical use.

Abstract

The interaction of high-temperature plasma with matter has several potential applications. In this study, we generated laser-induced plasma through single and successive laser energy deposition. The lifetime of the plasma is of paramount importance in most practical applications. However, this cannot be achieved with a single high-energy pulse due to some practical challenges. Therefore we carried out experimental and numerical investigations on the successive laser energy deposition and demonstrated its importance compared to the single pulse energy deposition. It has been observed that during successive energy deposition, the absorption of energy from the second pulse is nonlinear, and the reason for such behaviour is explained in this study. Due to the nonlinear absorption from the second pulse, this study therefore aims to present the pulse interval configuration between the successive pulses with which it is effective for practical use. In this study, some interesting and first direct observations of some new physical phenomena (generation of fourth-lobe and multiple shock waves) are observed during successive energy deposition when the pulse interval is 50 $ \mu{s} $ and 100 $ \mu{s} $. This study also adopted new approch based on Maxwell's theory of momentum exchange between light and matter to explain the newly observed and some previously unexplained physical phenomena. Finally, to understand the evolution of the laser-induced plasma, the volume and volumetric expansion rate are calculated, which can be useful in determining its lifetime and mixing rate with the surrounding medium.