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

Abstract

The interaction of high-temperature plasma with the matter has several potential applications. This study 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 certain 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 behavior is explained in this study. Due to the nonlinear absorption from the second pulse, this study aims to present the pulse-interval configuration between the successive pulses with which it can be effective for practical use. In this study, some interesting physical phenomena (generation of fourth-lobe and multiple shock waves) are observed during successive energy deposition when the pulse interval is 50 and 100 μs. This study also adopted a new approach based on Maxwell’s theory of momentum exchange between light and matter to provide a plausible explanation for the generation of the fourth-lobe. 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.