Laser Short-Pulse Heating of Silver-Chromium Assembly: Improved Formulation of Electron Kinetic Theory Approach

2007 ◽  
Vol 52 (6) ◽  
pp. 565-589 ◽  
Author(s):  
Bekir Sami Yilbas
Keyword(s):  
Kinetic Theory ◽  
Pulse Heating ◽  
Short Pulse ◽  
Theory Approach

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.

Electron kinetic theory approach for sub-nanosecond laser pulse heating

2000 ◽  
Vol 214 (10) ◽  
pp. 1273-1284 ◽  
Author(s):  
B S Yilbas ◽  
S Z Shuja
Keyword(s):  
Laser Pulse ◽  
Kinetic Theory ◽  
Temperature Rise ◽  
Pulse Heating ◽  
Equation Model ◽  
Nanosecond Laser Pulse ◽  
Nanosecond Laser ◽  
Level Energy ◽  
Theory Approach ◽  
Heating Model

Laser short-pulse heating initiates non-equilibrium thermodynamic processes in the surface vicinity of solid substrates that are subjected to the pulse heating. The Fourier heating model, however, overestimates the temperature rise in this region. Consequently, it becomes essential to consider a heating model employing a microscopic level energy exchange mechanism in the surface vicinity. In the present study, electron kinetic theory, Fourier theory (one-equation model) and a two-equation model are introduced for sub-nanosecond laser heating pulses. The effect of laser pulse intensity on the temperature rise is also considered. The equations resulting from the models are solved numerically for gold and chromium substrates. The predictions are validated for a triangular pulse and a silicon substrate. It is found that electron kinetic theory and a two-equation model both predict lower temperatures in the surface vicinity at early heating times. As the pulse heating progresses, the predictions of both models converge to the result of a one-equation model.

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.

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