THERMAL CONDUCTIVITY OF CLEAR FUSED SILICA AT HIGH TEMPERATURES. Research Report 44

The thermal conductivity of clear fused silica was measured over the temperature range 300 to 2100 deg 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 x 10/sup -3/ and 2.8 x 10/sup -3/ cal/cm sec deg K at room temperature, and between 4.5 x 10/sup -3/) and 5.5 x 10/sup -3/ cal/cm sec deg K over the temperature range 1000 to 2100 deg K. (auth)