CC BY
1*
ALT'23
The 30th International Conference on Advanced Laser Technologies
LM-O-25
Pressure recoil behavior in picosecond laser metal interaction:
MD simulation
D.S.Ivanov1, A.A.Samokhin2*
1-P. N. Lebedev Physical Institute of Russian Acad. Sci., Leninskiy Pr. 53, 119991 Moscow, RussianFederation 2- Prokhorov General Physics Institute of the Russian Academy of Sciences, st.Vavilova 38, Moscow, 119991 Russian
Federation
Main author * email address: asam40@mail.ru
The numerical method combining Molecular Dynamic (MD) with Two Temperature Model (TTM) [1] is used to describe ps laser pulse interaction with thick Al film. Thus, the MD-TTM method described the laser-induced non-equilibrium phase transition with atomic precision, whereas accounts on the effect of free carriers (conduction band electrons) in the continuum. The Al target heating due to 30 ps laser pulses is simulated up to the states where the pressure recoil Pr can probably exceed the critical pressure Pc for liquid-vapor phase transition. However, this exceeding does not necessarily exclude surface evaporation or subcritical explosive boiling processes since pressure Ps and temperature Ts at the irradiated surface can be lower than its critical values. The performed investigations shed light on the real critical parameter's values for Al (and most of metals) that are not yet well defined experimentally and theoretically.
100 150
Time, ps
Fig. 1:Evolution of pressure at 200 nm depth below the surface for a range of fluences.
From Fig.1 one can see how small vaporization peak appears on the thermoacoustic pressure signal maximum and grows at higher fluence E with displacing at earlier times. Another somewhat delayed pressure peaks visible at t = 200 ps, 195 ps and 245 ps for E = 500 mJ/cm2, 950 mJ/cm2 and 1000 mJ/cm2 are due to the cavitation effect which is well known for longer time scales [2] and is probably responsible [3] for the delayed effects mentioned in [4,5]. The situation needs further investigation as well as the problem of metal-dielectric transition during laser ablation [3].
[1]D.S. Ivanov et al., Experimental and Theoretical Investigation of Periodic Nanostructuring of Au with UV Laser Near the Ablation Threshold, Phys. Rev. Appl. 4, 064006 (2015).
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[3] A.A. Samokhin, P. A.Pivovarov, , E.V. Shashkov, et al. On the Metal-Nonmetal Transition under Nanosecond Laser Ablation. Phys. Wave Phen. 29, 204-209 (2021).
[4]A.V. Pakhomov, M.S. Thompson, D.A. Gregory, Laser-induced phase explosions in lead, tin and other elements: microsecond regime and UV-emission, J. Phys. D: Appl. Phys. 36, 2067 (2003).
[5] J.H. Yoo, S.H. Jeong, R. Greif, and R.E. Russo, Explosive change in crater properties during high power nanosecond laser ablation of silicon, J. Appl. Phys. 88, 1638 (2000)
