Thermal Conductivity of Clear Fused Silica at High Temperatures

The thermal conductivity of clear fused silica was measured over the temperature range 300–2100°K in an experiment which minimized radiative energy transport. This was a steady-state experiment involving the measurement of the electric current and voltage drop through a fine tungsten wire which was embedded along the axis of a cylindrical silica rod. The wire served both as a heating element and as a resistance thermometer. Thermal conductivities were calculated by graphical evaluation of the rate of change of electric power with temperature at different temperatures. The experiment yielded thermal conductivities between 2.6×10−3 and 2.9×10−3 cal/cm sec°K at room temperature, and between 4.5×10−3 and 5.5×10−3 cal/cm sec°K over the temperature range 1000–2100°K.