A computational fluid dynamics model for co-deposition of silica and germania in the MCVD process

The modified chemical vapor deposition (MCVD) process is used to create the doped silica preforms that are subsequently drawn to optical fiber. This paper reports on the extension of a computational fluid dynamics model of the MCVD process to include the simultaneous creation, transport and wall deposition of silica and germania particles. Simulations indicate the crucial role played by the interplay between chemical kinetics and equilibria along the substrate tube. Illustrative results show the likely impact of particle size on deposition patterns, along with a possible explanation for the observed high wastage of germanium in this process.