A Model of Ultra-Short Pulsed Laser Ablation of Metal with Considering Plasma Shielding and Non-Fourier Effect

Abstract

In this paper, a non-Fourier heat conduction model of ultra-short pulsed laser ablation of metal is established that takes into account the effect of the heat source, laser heating of the target, the evaporation and phase explosion of target material, the formation and expansion of the plasma plume, and interaction of the plasma plume with the incoming laser. Temperature dependent optical and thermophysical properties are also considered in the model due to the properties of the target will change over a wide range during the ultra-short pulsed laser ablation process. The results show that the plasma shielding has a great influence on the process of ultra-short pulsed laser ablation, especially at higher laser fluence. The non-Fourier effect has a great influence on the temperature characteristics and ablation depth of the target. The ultra-short pulsed laser ablation can effectively reduce the heat affected zone compared to nanosecond pulsed laser ablation. The comparison between the simulation results and the experimental results in the literature shows that the model with the plasma shielding and the non-Fourier effect can simulate the ultra-short pulsed laser ablation process better.

Controlling the plasma electron number density of copper metal using NIR picosecond laser-induced plasma spectroscopy

“…Transition probability A ki [10 ------------------------- about 1.09 × 10 16 to 4.75 × 10 16 cm -3 depending on the laser pulse energy, which is in agreement with previous results by others [23][24][25]. This increase of the electron density with the laser pulse energy can be understood due to an increase in the mass-ablation rate with the increase of the laser pulse energy [26,27] as indicated in Eq.…”

Heat Accumulation-Induced Surface Structures at High Degrees of Laser Pulse Overlap on Ti6Al4V Surfaces by Femtosecond Laser Texturing

“…In the case of a single pulse texturing, the plasma plume is formed within ten picoseconds, and a combination of atoms, ions, and particle agglomerates are ejected [ 41 ]. In multiple laser pulse texturing, the subsequent pulses interact with the plasma cloud generated by the previous laser pulse, resulting in inefficient energy deposition known as plasma shielding [ 41 , 42 ]. A high-density plasma cloud was observed even after a few nanoseconds at fluences above the ablation threshold [ 43 ].…”

Effect of Laser Pulse Overlap and Scanning Line Overlap on Femtosecond Laser-Structured Ti6Al4V Surfaces

“…When discussing the creation of the surface structure depending on the different LO and PO parameters, the dynamics of the laser structuring process itself has to be considered. Firstly, when looking at a single femtosecond laser pulse, heat conduction occurs if the boiling temperature is not exceeded [40]. Initial absorption of the laser irradiation of a laser pulse occurs from the free electrons in the first femtoseconds due to inverse bremsstrahlung.…”

“…When considering multiple laser shots at high repetition rates, several effects occur. If the ablated material results in a plasma plume, interaction with the incoming laser light by the next laser pulse takes place and leads to an inefficiency of energy deposition in the laser spot, which is referred to as plasma shielding [40,49]. Photoionization of excited atoms and electron-ion as well as electron-neutral bremsstrahlung are the mechanisms that lead to an absorption of a part of the incident photons before hitting the target and, consequently, to an increase of the plasma temperature [32].…”