High power continuous wave laser heating of graphite in a high temperature range up to 3800 K
Laurent Gallais, T. Vidal, E. Lescoute, Yves Pontillon, Jean‐Luc Rullier
Abstract
As graphite is an important material for several applications, the evaluation of its properties at very high temperatures is of major importance. Conducting studies at temperatures >2800 K is, however, very challenging, and the amount of available data in the literature is, therefore, very limited. This paper presents a methodology that compares experimental data with simulation results following a progressive increase of the temperature range investigated. The study was conducted on a commercial polycrystalline graphite produced by sintering (EDM-3 from POCO) under high power continuous laser heating (kW ytterbium at a wavelength of 1080 nm). Experiments were done inside a vacuum chamber equipped with pyrometers and cameras allowing fine monitoring of the temperature of the samples. A 3D numerical model has been developed based on the finite element method to analyze the experimental results. The evolution of the thermal and optical properties of EDM-3 with temperature is required for correctly modeling laser/material interactions. By running a sequential comparison of calculation with a dedicated experiment, we achieve better knowledge of such properties. From this study, we obtain estimations of the evolution of thermal conductivity, emissivity, and evaporation rate up to 3800 K of amorphous graphite.