Formation and evolution of multiple-core structures in laser-sustained plasmas

We report on the formation of multiple-core structures in laser-sustained plasmas (LSPs) through the utilization of an improved two-dimensional laser-thermal-hydrodynamically coupled fluid model. Our findings reveal that steady-state LSPs exhibit various temperature structures, including single, double, and triple cores, as the input laser power increases incrementally. The spatiotemporal distributions of these multiple-core structures are demonstrated, and the presence of an LSP core is identified when the rate of enthalpy change becomes positive. This behavior is predominantly influenced by factors such as laser power absorption, radiation, and diffusion along the laser path. The obtained results provide explicit insights into the temperature structures within LSPs, thereby potentially contributing to the advancement of LSP-based light sources for optical wafer defect inspection in the semiconductor industry.