A Critical Assessment Regarding Two-Temperature Models: An Investigation of the Different Forms of Two-Temperature Models, the Various Ultrashort Pulsed Laser Models and Computational Methods

Abstract

Nowadays, lasers are used in a wide variety of manufacturing processes, such as cutting, sintering and welding. The evolution of laser technologies has led to the creation of ultrashort pulsed lasers, with a pulse duration below 10 ps, which have the ability, on the contrary with the conventional lasers, to stimulate separately the electrons and the lattice. Thus, two different temperatures, the electron temperature and the lattice temperature appear. This cannot be described by the classical Fourier heat equations and thus the Two-Temperature Model (TTM) has been proposed. In the TTM, a heat equation that describes the electron temperature is conjugated with a heat equation that describes the lattice temperature. Except from the correct implementation of the heat equations, other factors that should be taken into consideration during the development of the TTM simulation are the correct and accurate modelling of the ultrashort pulsed laser and the appropriate selection of the computational method regarding the targets of each specific study. The aim of this review paper is not only to present the current literature regarding the different TTMs, ultrashort pulsed laser models and computational methods, but also to create mind maps that will help the researcher to choose the most appropriate TTM and computational method regarding the targets of each specific study. Moreover, in this review paper, recommendations for future work are given, regarding the more accurate and realistic modelling of the laser source.