The role of mass removal mechanisms in the onset of ns-laser induced plasma formation

Abstract

The present study focuses on the role of mass removal mechanisms in ns-laser ablation. A copper sample is placed in argon, initially set at standard pressure and temperature. Calculations are performed for a 6 ns laser pulse with a wavelength of 532 nm and laser fluences up to 10 J/cm 2. The transient behavior in and above the copper target is described by a hydrodynamic model. Transmission profiles and ablation depths are compared with experimental results and similar trends are found. Our calculations reveal an interesting self-inhibiting mechanism: volumetric mass removal in the supercritical region triggers plasma shielding and therefore stops proceeding. This self-limiting process indicates that volumetric mass removal does not necessarily result in large ablation depths. V

States and properties of metallic systems at a threshold breakdown of the through holes under power laser action (part 2).Susceptibility

“…A critical temperature was measured by the method of explosion of thin wire by a large current [14]: T cr = 8390 K. In [15] a theoretical value T cr = 7800K is got from the calculations of modelling a phase diagram. But in such calculations, if reflectivity (absorptions) were used, then for such temperatures they would be got only by extrapolation on high temperatures, as a direct measuring of these coefficients at high temperatures, higher 3000Ʉ in literature were not met.…”

Nanosecond Laser Ablation: Mathematical Models, Computational Algorithms, Modeling

“…At the same time, the understanding of fundamental physics of internal structure of plasma plumes and their spatiotemporal evolution in the process of plasma expansion in the background gas at atmospheric pressure is of decisive importance for many engineering applications. For this reason, nanosecond laser ablation continues to be an area of active research in which mathematical modeling plays an increasing role [28][29][30][31].…”

“…Continuous models based on the equations of continuous medium mechanics are realized, as a rule, in the form of hydrodynamic models [18,24,28,30,31,[38][39][40][41][42] and use the minimum of information and operate with average values of physical characteristics calculated on infinitesimal volume. The methods for solving them are more compact, they have higher accuracy and a relatively small amount of computation.…”

States and Properties of Metallic Systems at a Threshold Breakdown of the Through Holes Under Power Laser Action. Threshold Breakdown of Through Holes in Metal Foils by Powerful Laser Radiation (Part 1)

“…Affecting of powerful laser irradiation on metallic (dielectric and semiconductor) targets leads to formation of craters and holes, moving away of substance from a target -to the ablation [1][2][3][4][5][6][7][8][9][10][11][12]. The special role are here playing the different thermodynamic states -"solid, liquid, gas, plasma" in which substance consistently goes across.…”

“…Also, characteristics, which show that a substance is in a critical state (there is "liquid metal-gas" transition at the critical temperature), are also absent. Nevertheless, at certain cases it is possible to specify characteristics showing closeness to the critical temperature [9] and even to fix the borders of spinodal in a transition "liquid-gas" [3].…”