Effect of magnetic field-dependent effective thermal conductivity of melted layer on nanosecond laser ablation of copper and formation of nanoparticles at atmospheric air pressure

摘要

For a nanosecond laser ablation of metals, the key physical phenomena involved are thermal evaporation, melt ejection, instability of the molten metal, etc., which depend on the initial temperature evolution in the metal. Understanding the evolution of temperature of the metal needs an effective simulation. In the present paper, we report on the finite element method-based simulation of nanosecond laser ablation of copper in the absence and presence of the magnetic field. Our studies showed that the effective thermal conductivity of the melted layer on the copper surface in the presence of the magnetic field affects the viscosity of the layer, mass ablation rate, instability, and then particle formation. The calculations showed that the condensed nuclei of large critical size are produced in the magnetic field. It is attributed to an increase in the collision rate of plasma particles in the magnetically confined plasma. The simulations are in good agreement with the experimentally measured values.