Molecular Dynamics Study of Phase Change Mechanisms During Femtosecond Laser Ablation

2004 ◽  
Vol 126 (5) ◽  
pp. 727-734 ◽  
Author(s):  
Xianfan Xu ◽  
Changrui Cheng ◽  
Ihtesham H. Chowdhury
Keyword(s):  
Molecular Dynamics ◽  
Laser Ablation ◽  
Femtosecond Laser ◽  
Phase Change ◽  
Change Process ◽  
Femtosecond Laser Ablation ◽  
Femtosecond Laser Irradiation ◽  
Maximum Temperature ◽  
Transient Temperature ◽  
Phase Change Process

In this work, Molecular Dynamics (MD) simulation is employed to investigate femtosecond laser ablation of copper, with an emphasis on the understanding of the mechanism of phase change during laser ablation. Laser induced heat transfer, melting, surface evaporation, and material ablation are studied. Theoretically, it has been suggested that under intense femtosecond laser irradiation, the material undergoes a volumetric phase change process; its maximum temperature can be close to or even above the thermodynamic critical point. The MD simulations allow us to determine the transient temperature history of the irradiated material and to reveal the exact phase change process, which explains the mechanisms of femtosecond laser ablation. A finite difference calculation is also performed, which is used to compare results of heating and melting prior to a significant amount of material being ablated.

Molecular Dynamics Study of Mechanism of Ablation Induced by a Femtosecond Laser Pulse

2003 ◽  
Author(s):  
Changrui Cheng ◽  
Xianfan Xu
Keyword(s):  
Molecular Dynamics ◽  
Laser Ablation ◽  
Laser Pulse ◽  
Femtosecond Laser ◽  
Critical Point ◽  
Change Process ◽  
Femtosecond Laser Ablation ◽  
Md Simulations ◽  
Femtosecond Laser Irradiation ◽  
Transient Temperature

In this work, molecular dynamics (MD) simulations are carried out to study femtosecond laser ablation of a metal, with an emphasis on the understanding of the mechanism of laser ablation. Theoretically, it has been shown that under intense femtosecond laser irradiation, the material can undergo a volumetric phase change process; its temperature can be close to or even above the critical point. MD simulations allow us to determine the transient temperature of the irradiated material as well as the transient thermodynamic state, which explain the mechanisms of femtosecond laser ablation.

Mechanisms of femtosecond laser ablation of Ni3Al: Molecular dynamics study

2021 ◽  
Vol 133 ◽  
pp. 106505
Author(s):  
Zhen Zhang ◽  
Zenan Yang ◽  
Chenchong Wang ◽  
Qiang Zhang ◽  
Shuai Zheng ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Laser Ablation ◽  
Femtosecond Laser ◽  
Femtosecond Laser Ablation

Femtosecond Laser Ablation of Titanium and Silicon

2000 ◽  
Author(s):  
Mengqi Ye ◽  
Costas P. Grigoropoulos
Keyword(s):  
Laser Ablation ◽  
Femtosecond Laser ◽  
Laser Fluence ◽  
Laser System ◽  
Femtosecond Laser Ablation ◽  
Laser Pulses ◽  
Femtosecond Laser Irradiation ◽  
Nanosecond Laser ◽  
Iccd Camera ◽  
Plume Emission

Abstract Femtosecond laser ablation of titanium and silicon samples has been studied via time-of-flight (TOF), emission spectroscopy and microscopy measurement. Laser pulses of around 100 fs (FWHM) at λ = 800 nm were delivered by a Ti:sapphire femtosecond laser system. A vacuum chamber with a base pressure of 10−7 torr was built for ion TOF measurement. These ion TOF spectra were utilized to determine the velocity distribution of the ejected ions. While nanosecond laser ablation typically generates ions of a few tens of eV, femtosecond laser irradiation even at moderate energy densities can produce energetic ions with energies of up to a few keV. The most probable energy of these fast ions is proportional to the laser fluence. The structure and number of peaks of the TOF spectra varies with the laser fluence. Images of plume emission were captured by an intensified CCD (ICCD) camera. The plume emission spectrum was analyzed by a spectrometer. Laser ablated craters were measured by an interferometric microscope and a scanning electron microscope (SEM). Ablation yield was expressed as a function of laser fluence, and number of shots.

Femtosecond laser ablation of polystyrene: A molecular dynamics study

2015 ◽  
Vol 132 (43) ◽  
pp. n/a-n/a
Author(s):  
Yanhua Huang ◽  
Chengwei Song ◽  
Junjie Zhang ◽  
Tao Sun
Keyword(s):  
Molecular Dynamics ◽  
Laser Ablation ◽  
Femtosecond Laser ◽  
Femtosecond Laser Ablation

scholarly journals Phase Change Characteristics of Ultra-Thin Liquid Argon Film over different Flat Substrates at High Wall Superheat for Hydrophilic/Hydrophobic Wetting Condition: A Non-Equilibrium Molecular Dynamics Study

2017 ◽  
Vol 29 (1) ◽  
pp. 49-55 ◽  
Author(s):  
Mohammad Nasim Hasan ◽  
SM Shavik ◽  
KF Rabbi ◽  
KM Mukut ◽  
AKMM Morshed
Keyword(s):  
Molecular Dynamics ◽  
Phase Change ◽  
Change Process ◽  
Liquid Argon ◽  
Surface Wettability ◽  
Phase Change Process ◽  
Wall Superheat ◽  
Change Characteristics ◽  
Non Equilibrium Molecular Dynamics ◽  
Solid Liquid

Non-equilibrium molecular dynamics simulations have been conducted to understand the effect of solid-liquid interfacial wettability and surface material on the phase change phenomena of the thin liquid argon film placed over flat substrate at high wall superheat. The molecular system consists of a three phase simulation domain involving solid wall, liquid argon and argon vapor. After the system is thermally equilibrated at 90K and kept in equilibrium for a while, a high wall superheat (250K that is far above the critical temperature of argon) is induced at the liquid boundary so that the liquid undergoes ultrafast heating. Both hydrophilic and hydrophobic surfaces were considered in the present study in order to observe the effect of surface wettability on phase change characteristics for three different solid substrate materials namely, Platinum (Pt), Silver (Ag) and Aluminium (Al). Results obtained in the present study are discussed in terms of transient atomic distribution inside system domain, heat flux characteristics across the solid-liquid interface together with evaporative mass flux from liquid argon. Simulation results show that, depending on the surface wetting condition, the phase change process appears to be very different (explosive/ diffusive) for all three substrate materials under consideration. Among three materials considered herein, Al is found to offer the least favourable condition for phase change process while Pt and Ag show similar heat and mass transfer characteristics for both hydrophilic and hydrophobic wetting conditions. Surface wettability effect is found to be more prominent than the effect of substrate material in thin film liquid phase change phenomena.Journal of Chemical Engineering, Vol. 29, No. 1, 2017: 49-55

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