Apparatus to Measure the Thermal Conductivity of Powders in Vacuum from 120 to 350°K

An apparatus, enclosed in a sand-cast aluminum vacuum chamber capable of retaining pressures of 10−5–10−6 Torr, was used to measure the thermal conductivity of powder samples in vacuum. The base of the sample was heated by the temperature bath on which it rested and the top surface of the sample radiated into a cavity which was maintained at liquid nitrogen temperature (77°K). The thermal conductivity of the powders was calculated from the emitted flux, the sample thickness, and the bath temperature.