Entropy Generation Due to Laser Short Pulse Heating: Consideration of the Seebeck Effect
The temperature in lattice and electron sub-systems differs significantly during laser short-pulse heating of solids. In this case, collisional processes (between the sub-systems), govern the energy transport. Moreover, due to a large electron temperature difference within the substrate material, electrons flow from a high temperature region to a low temperature region, which results in a Seebeck current. In this case, electrons work against the potential charge. In the present study, the temperature field in the gold-copper two layer assembly is computed using the electron kinetic theory approach. The Seebeck coefficient is derived and determined in the assembly. The volumetric rate of entropy generation in the electron and lattice sub-systems due to the temperature field and the Seebeck effect is predicted. It is found that a noticeable change in the Seebeck coefficient occurs across the layers despite the smooth changes in the electron temperature. The rate of the volumetric entropy generation is high just below the surface whereas the entropy generation rate decreases with increasing depth from the surface in the lattice sub-system.