scholarly journals Simulation of laser ablation of metals for nanoparticles production

2016 ◽  
Vol 41 ◽  
pp. 1660143 ◽  
Author(s):  
R. V. Davydov ◽  
V. I. Antonov ◽  
T. I. Davydova
Keyword(s):  
Experimental Data ◽  
Laser Ablation ◽  
Femtosecond Laser Ablation ◽  
Hydrodynamic Equations ◽  
Temperature Model ◽  
Wide Range ◽  
Simulation Results ◽  
Range Equation ◽  
Two Temperature ◽  
Good Agreement

In this paper a mathematical model for femtosecond laser ablation of metals is proposed, based on standard two-temperature model connected with 1D hydrodynamic equations. Wide-range equation of state has been developed. The simulation results are compared with experimental data for aluminium and copper. A good agreement for both metals with numerical results and experiment shows that this model can be employed for choosing laser parameters to better accuracy in nanoparticles production by ablation of metals.

Materials Removals During Femtosecond Laser Non-Thermal Ablation of Dielectrics

2006 ◽  
Author(s):  
Lan Jiang ◽  
Hai-Lung Tsai
Keyword(s):  
Experimental Data ◽  
Laser Ablation ◽  
Femtosecond Laser ◽  
Electron Density ◽  
Free Electron ◽  
Femtosecond Laser Ablation ◽  
Threshold Fluence ◽  
Plasma Model ◽  
Free Electron Density ◽  
Two Temperature

It remains a big challenge to theoretically predict the material removals mechanism in femtosecond laser ablation. To bypass this unresolved problem, many calculations of femtosecond laser ablation of non-metals have been based on free electron density distribution without the actual consideration of the phase change mechanism. However, this widely-used key assumption needs further theoretical and experimental confirmations. By combining the plasma model and improved two-temperature model developed by the authors, this study focuses on investigating ablation threshold fluence, depth, and shape during femtosecond laser ablation of dielectrics through non-thermal processes (the Coulomb explosion and electrostatic ablation). The predicted ablation depths and shapes in fused silica, by using 1) the plasma model only and 2) the plasma model plus the two-temperature equation, are both in agreement with published experimental data. The widely-used assumptions for threshold fluence, ablation depth, and shape in the plasma model based on free electron density are validated by the comparison study and experimental data.

scholarly journals Improved two-temperature model and its application in femtosecond laser ablation of metal target

2010 ◽  
Vol 28 (1) ◽  
pp. 157-164 ◽  
Author(s):  
Ranran Fang ◽  
Duanming Zhang ◽  
Hua Wei ◽  
Zhihua Li ◽  
Fengxia Yang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Laser Ablation ◽  
Femtosecond Laser ◽  
Laser Fluence ◽  
Femtosecond Laser Ablation ◽  
Temperature Model ◽  
Metal Target ◽  
Temperature Dependent ◽  
Two Temperature

AbstractAn improved two-temperature model to describe femtosecond laser ablation of metal target was presented. The temperature-dependent heat capacity and thermal conductivity of the electron, as well as electron temperature-dependent absorption coefficient and absorptivity are all considered in this two-temperature model. The tailored two-temperature model is solved using a finite difference method for copper target. The time-dependence of lattice and electron temperature of the surface for different laser fluence are performed, respectively. The temperature distribution of the electron and lattice along with space and time for a certain laser fluence is also presented. Moreover, the variation of ablation rate per pulse with laser fluence is obtained. The satisfactory agreement between our numerical results and experimental data indicates that the temperature dependence of heat capacity, thermal conductivity, absorption coefficient and absorptivity in femtosecond laser ablation of metal target must not be neglected. The present model will be helpful for the further experimental investigation of application of the femtosecond laser.

scholarly journals Femtosecond-Laser-Ablation Dynamics in Silicon Revealed by Transient Reflectivity Change

Micromachines ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 14
Author(s):  
Tao Feng ◽  
Gong Chen ◽  
Hainian Han ◽  
Jie Qiao
Keyword(s):  
Femtosecond Laser ◽  
Stable State ◽  
Femtosecond Laser Ablation ◽  
Drude Model ◽  
Temperature Model ◽  
Plasma Generation ◽  
High Fluences ◽  
Microscopy Technique ◽  
Wide Range ◽  
Two Temperature

The dynamics of ablation in monocrystalline silicon, from electron-hole plasma generation to material expansion, upon irradiation by a single femtosecond laser pulse (1030 nm, 300 fs pulse duration) at a wide range of fluences is investigated using a time-resolved microscopy technique. The reflectivity evolution obtained from dynamic images in combination with a theoretical Drude model and a Two-Temperature model provides new insights on material excitation and ablation process. For all fluences, the reflectivity increased to a temporary stable state after hundreds of femtoseconds. This behavior was predicted using a temperature-dependent refractive index in the Drude model. The increase in velocity of plasma generation with increasing fluence was theoretically predicted by the Two-Temperature model. Two ablation regimes at high fluences (>0.86 J/cm2) were identified through the measured transient reflectivity and ablation crater profile. The simulation shows that the fluence triggering the second ablation regime produces a boiling temperature (silicon, 2628 K).

The penetration and ricochet of ogive-nosed rigid projectiles obliquely impacting metallic targets

2021 ◽  
pp. 204141962110377
Author(s):  
Yaniv Vayig ◽  
Zvi Rosenberg
Keyword(s):  
Experimental Data ◽  
Numerical Simulations ◽  
Dynamic Pressure ◽  
Oblique Impacts ◽  
Simulation Results ◽  
The Impact ◽  
Penetration Depths ◽  
Resistance To Penetration ◽  
Good Agreement

A large number of 3D numerical simulations were performed in order to follow the trajectory changes of rigid CRH3 ogive-nosed projectiles, impacting semi-infinite metallic targets at various obliquities. These trajectory changes are shown to be related to the threshold ricochet angles of the projectile/target pairs. These threshold angles are the impact obliquities where the projectiles end up moving in a path parallel to the target’s face. They were found to depend on a non-dimensional entity which is equal to the ratio between the target’s resistance to penetration and the dynamic pressure exerted by the projectile upon impact. Good agreement was obtained by comparing simulation results for these trajectory changes with experimental data from several published works. In addition, numerically-based relations were derived for the penetration depths of these ogive-nosed projectiles at oblique impacts, which are shown to agree with the simulation results.

Dynamic Temperature Testing and Modeling for an Automatic Transmission Clutch

2001 ◽  
Author(s):  
Thomas DeMurry ◽  
Yanying Wang
Keyword(s):  
Experimental Data ◽  
Real Time ◽  
Automatic Transmission ◽  
Thermal Characteristics ◽  
Torque Converter ◽  
Telemetry System ◽  
Temperature Model ◽  
And Control ◽  
Good Agreement ◽  
Dynamometer Test

Abstract The primary objectives of this study are (1) to validate the hardware design and control methodologies for preserving the thermo-mechanical integrity of a launch clutch emulating a torque converter and (2) to develop a simple, control oriented clutch-temperature model that may act as a virtual thermocouple in the processor of an automobile for real-time clutch-temperature predictions. In a dynamometer test cell, a Ford CD4E transaxle is instrumented with a thermocouple-based telemetry system to investigate clutch thermal characteristics during engagements, neutral idle, single and repeated launching, torsional isolation, and hill holding. A nonlinear, SIMULINK™-based model for estimating temperature is developed. The results from the simulations are in good agreement with the experimental data.

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