Laser Heating of Stationary Fused Silica Rods and Fibers: Effects of Heat Source and Radiation Modeling

This paper investigates the effects of surface and volumetric absorption of laser energy on the temperature prediction of CO₂ laser heating of silica rods and fibers. Radiative transfer within the fused silica is modeled using the diffusion approximation and the zonal method. Around 25 K in temperature difference is observed when the diffusion approximation is used in place of the zonal method to model radiative transfer in fused silica. The spectral dependence of the fused silica absorption coefficient in semitransparent wavelengths is approximated by a two-band model. The Weighted-Sum-of-Gray-Gas (WSGG) method is used to calculate the radiative source term for the zonal method. The importance of using the zonal method for radiative heat transfer in fused silica is also discussed.