Modelagem da cinética do processo de deposição modificada de vapor químico (MCVD) para o controle do índice de refração em fibras ópticas de sílica para lasers de potência

Abstract

This study aims to develop a numerical procedure for the computational modeling of the kinetics of the Modified Chemical Vapor Deposition process (MCVD) in a laminar flow. The numerical model solves the steady state energy and mass transport equations by means of the Finite Volume Method (FVM), with a commercial CFD software, and the Finite Difference Method (FDM). The results were the velocity and temperature fields for the carrier gas (O2) and the concentration fields of reagents and products involved in the oxidation reactions. The deposition efficiency was estimated taking into account the thermophoretic velocity and the concentration fields of the species involved, where it was observed that the efficiency for SiO2 was slightly higher than for GeO2 for all analyzed cases. A brief analysis was carried out to observe the effect of variables such as maximum torch temperature and mass flow on the deposition efficiency. The path of the oxide particles was determined from a Lagrangian approach, using the Euler's integration method. It was possible to observe the behavior of the particles along the radial positions. The particles nearer the tube wall were more susceptible to deposition due to the highest temperature gradients to which they were exposed.