The formation and deposition of SiO2 aerosols in optical fiber manufacturing torches

Abstract Pyrogenic silica particle formation for optical waveguide manufacturing precludes the empirical approach to process control and optimization. The intimate coupling of flame chemistry, particle formation, and subsequent deposition necessitates the development of mathematical models which reproduce the intrinsic physics of the system, along with non-intrusive optical diagnostics to probe the extensive process parameter space. We present sheet-beam laser scattering and thermal tagging techniques to measure particle distribution and velocity, respectively. This information is used to compare particle deposition model calculations with data collected. In addition, two distinct particle formation mechanisms, oxidation and hydrolysis, have been observed which have profound effects on particle deposition efficiencies. Model calculations agree well with data and predict accurately the very high deposition efficiencies ( ca 100%) observed in the oxidation mode of particle formation.