Entropy Production During Laser Picosecond Heating of Copper

2002 ◽  
Vol 124 (3) ◽  
pp. 204-213 ◽  
Author(s):  
Bekir Sami Yilbas
Keyword(s):  
Entropy Production ◽  
Energy Transport ◽  
Pulse Heating ◽  
Short Pulse ◽  
Surface Region ◽  
Irreversible Processes ◽  
Heating Process ◽  
Theory Approach ◽  
Lattice Systems ◽  
Nonequilibrium Energy

Nonequilibrium energy transport taking place in the surface region of the metallic substrate due to laser short-pulse heating results in entropy production in electron and lattice systems. The entropy analysis gives insight into the irreversible processes taking place in this region during the laser short-pulse heating process. In the present study, entropy production during laser shortpulse heating of copper is considered. Equations governing the nonequilibrium energy transport are derived using an electron kinetic theory approach. The entropy equations due to electron and lattice systems and coupling of these systems are formulated. The governing equations of energy transport and entropy production are solved numerically. Two pulse shapes, namely step input intensity and exponential intensity, are employed in the analysis. It is found that entropy production due to coupling process attains higher values than those produced due to electron and lattice systems. The effect of pulse shape on the entropy production inside the substrate material is significant.

Laser short-pulse heating with time-varying intensity and thermal stress development in the lattice subsystem

2005 ◽  
Vol 219 (1) ◽  
pp. 73-81 ◽  
Author(s):  
B S Yilbas ◽  
A F M Arif
Keyword(s):  
Thermal Stress ◽  
Lattice Site ◽  
Energy Transport ◽  
Pulse Heating ◽  
Short Pulse ◽  
High Stress ◽  
Surface Region ◽  
Substrate Material ◽  
Temperature Gradients ◽  
Stress Levels

Laser short-pulse heating of solid surfaces results in non-equilibrium energy transport in the region irradiated by the laser beam. Owing to the large temperature gradients in the lattice subsystem, high stress levels develop in the surface region of the substrate material. In the present study, temperature and stress fields in the substrate material are presented for the case of the laser short-pulse heating of gold. Electron kinetic theory and a two-equation heating model are introduced to account for non-equilibrium energy transport during the laser heating pulse. Laser pulses exponentially decaying with time are accommodated in the simulations. It is found that lattice site temperature gradients attain high values inspite of the low magnitude of the lattice site temperature. This, in turn, results in high stress levels in the surface region of the substrate material. Thermal stress is compressive owing to high thermal strain development and low displacement of the surface.

Laser short-pulse heating: Three-dimensional consideration

2001 ◽  
Vol 215 (9) ◽  
pp. 1123-1138 ◽  
Author(s):  
B. S. Yilbas
Keyword(s):  
Kinetic Theory ◽  
Energy Transport ◽  
Pulse Heating ◽  
Short Pulse ◽  
Three Dimensional ◽  
Gold Surface ◽  
Equation Model ◽  
Three Dimensions ◽  
Theory Approach ◽  
Energy Transfer Mechanism

Non-equilibrium energy transport takes place in solids once the laser pulse duration reduces to picoseconds or less. It is this energy transfer mechanism that defines the laser interaction process and therefore the rate at which the material is heated through the collisional process. In the present study, laser short-pulse heating of a gold surface is considered. An electron kinetic theory approach is introduced to model the energy transport process in three dimensions. The governing equation of energy transport is solved numerically, and the electron and lattice site temperatures are predicted. In order to validate the electron kinetic theory predictions, a two-equation model is employed to compute the temperature field in the substrate material. It is found that energy transport due to the diffusional process is unlikely during the heating period considered at present. The predictions of electron kinetic theory agree well with the results obtained from the two-equation model.

Study into laser short-pulse heating of a layered structure

2009 ◽  
Vol 224 (5) ◽  
pp. 1099-1111
Author(s):  
B S Yilbas
Keyword(s):  
Seebeck Coefficient ◽  
Temperature Rise ◽  
Layered Structure ◽  
Lattice Site ◽  
Pulse Heating ◽  
Short Pulse ◽  
Silicon Layer ◽  
Theory Approach ◽  
Seebeck Coefficients ◽  
Lead Layer

Laser short-pulse heating of a lead—silicon—gold-layered structure is considered and non-equilibrium equation in the lattice and electron subsystems is formulated using the electron kinetic theory approach. The Seebeck coefficient in the metallic and silicon layers is also formulated. Electron and lattice site temperature rise in the subsystems and the Seebeck coefficients are computed for time exponentially decaying pulse. The study is extended to include the influence of the first layer (lead layer) thickness on temperature rise and the Seebeck coefficients. It is found that the lattice site temperature across the interface of the lead and silicon layers increases sharply. The Seebeck coefficient predicted in the silicon layer is higher than in the metallic layers in the structure.

Analytical solution for electron and lattice site temperatures due to laser-induced non-equilibrium energy transport in metals

2010 ◽  
Vol 88 (7) ◽  
pp. 479-491 ◽  
Author(s):  
Hind M. Al-Theeb ◽  
Bekir S. Yilbas
Keyword(s):  
Experimental Data ◽  
Analytical Solutions ◽  
Energy Transport ◽  
Short Pulse ◽  
Substrate Material ◽  
Theory Approach ◽  
Short Pulse Laser ◽  
Numerical Predictions ◽  
Temperature Distributions ◽  
Pulse Laser Heating

The present study describes the modeling of short-pulse laser heating of gold and copper materials. The energy transport due to a laser short pulse is formulated using the electron kinetic theory approach. Electron and lattice temperature distributions inside the substrate material during the laser short pulse are formulated analytically. In the analysis, the Laplace transformation technique is used. The results obtained from the analytical solutions are compared with numerical predictions and experimental data. It is found that the results obtained from the numerical and analytical solutions for temperature distributions are in good agreement with the experimental data.

Analytical solution for laser short-pulse heating of two-dimensional solids: volumetric and surface heat source considerations

2013 ◽  
Vol 91 (7) ◽  
pp. 522-529
Author(s):  
B.S. Yilbas ◽  
A.Y. Al-Dweik
Keyword(s):  
Analytical Solution ◽  
Heat Source ◽  
Energy Transport ◽  
Pulse Heating ◽  
Short Pulse ◽  
Thermal Response ◽  
Solid Substrate ◽  
Surface Heat ◽  
Heat Sources ◽  
Power Intensity

An analytical solution for lattice temperature distribution in a metallic solid subjected to laser short-pulse heating is presented. The method of similarity solution is adopted for the solution of the diffusive–ballistic energy equation. Volumetric and surface heat sources are each incorporated separately in the analysis. The material thermal response due to both heat sources during the short heating period is analyzed. It is found that a volumetric heat source resulted in smaller temperature increase in the irradiated material than a surface heat source, despite the same laser power intensity being used in both cases. This is attributed to energy transport mechanisms taking place in the solid substrate due to volumetric and surface heat sources.

Non-equilibrium energy transport and entropy production due to laser short-pulse irradiation

2016 ◽  
Vol 94 (1) ◽  
pp. 130-138 ◽  
Author(s):  
H. Ali ◽  
B.S. Yilbas ◽  
A.Y. Al-Dweik
Keyword(s):  
Laser Pulse ◽  
Entropy Generation ◽  
Energy Transport ◽  
Pulse Heating ◽  
Short Pulse ◽  
Generation Rate ◽  
Entropy Generation Rate ◽  
Pulse Intensity ◽  
Laser Pulse Intensity ◽  
Nano Size

Laser short-pulse heating of a nano-size wire is considered and entropy generation rate is predicted during the heating pulse. The analytical solution of the heat equation is obtained using the Lie point symmetry for the laser short-pulse heating. The nano-size wire is assumed to be symmetric along its y-axis. Laser pulse intensity is considered to be Gaussian at the irradiated surface while the exponential decay of the laser pulse is incorporated in the time domain. It is found that surface temperature variation in the lattice subsystem almost follows the laser pulse intensity distribution at the surface. Entropy generation rate attains low values along the symmetry axis and it increases considerably in the region of the nano-size wire edges. This behavior is associated with the temperature gradient, which attains high values in the region close to the nano-size wire edge.

Sign in / Sign up

Export Citation Format

Share Document