A two-dimensional comprehensive hydrodynamic model for femtosecond laser pulse interaction with metals

Abstract

Femtosecond laser–metal interaction in air and the resultant early plasma evolution are investigated by a two-dimensional comprehensive hydrodynamic model in this paper. The model comprises a two-temperature model and a hydrodynamic model supplemented with a quotidian equation of state model, considering the relevant multiphysical phenomena during the laser–metal interaction. The experimental measurements for plasma expansion were carried out to validate the simulation results, using a shadowgraph technique and direct fluorescence measurement. The evolution of both the early plasma and plume plasma is investigated by the model. The early plasma is proved to be generated by electron emission and ambient gas ionization and splits into several portions during its expansion due to different mechanisms. The plume plasma comes from the target material ejection. The photoelectric emission is revealed to be the dominant electron emission mechanism at high laser intensities, while thermal emission is more important at low laser intensities. The electron emission process and early stage plasma are critical to ultrashort laser–metal interaction, especially at high laser intensities. Without considering this, the electron temperature can be overestimated by as much as 70%.

Hydrodynamic simulation of ultrashort pulse laser ablation of gold film

“…The main laser absorption mechanism for metals is inverse bremsstrahlung absorption. The other mechanisms such as absorption via ionization are insignificant since the nearly free electrons in metals are sufficient [12]. The absorption rates are calculated as a function of peak fluence based on the model setup.…”

“…Hydrodynamic models [HD; [12][13][14] have been developed to describe expansion and heating of targets irradiated by fs laser pulses. They achieve a balance between the calculation of material properties and time consumption.…”

Hydrodynamic Simulation of the Femtosecond Laser Processing of Metals

“…A hydrodynamic (HD) model has been developed to describe the expansion and heating of targets irradiated by laser pulses. (19,20) It achieves a balance between the calculation of material properties and the time required.…”

Simulations of interactions of high-energy proton beam with high dense matter based on two-dimensional quantum hydrodynamic model

“…In particular, the beammatter heating techniques are of considerable potential interest for driving an inertial confinement fusion (ICF) (Deutsch, 1986;1992;Deutsch et al, 1989;Hora, 2007;Hoffmann, 2008), where a target matter can be irradiated by intense ion beams and be transformed into a plasma of high density and high temperature, which can initiate fusion reactions (Deutsch, 1992;Tahir et al, 2005). Much work has been made to study the beam-matter heating including heavy ion (Hoffmann et al, 2010;Zhao et al, 2009), proton (Patel et al, 2003;Tahir et al, 2009), and laser beams (Zhao et al, 2012). Intense ion beams have emerged as efficient and flexible tool to heat a target to HED matter, where beam ions propagate in a target and volumetrically heat it over macroscopic volumes.…”