A cylindrical furnace with homogeneous temperature distribution for use in a cubic high-pressure press

Abstract

A cylindrical furnace with a homogeneous temperature distribution was designed for use in a cubic press by using the difference method. This method consists of three tubes and is applicable to the very small sample chamber of high-pressure apparatus. The temperature distribution in the furnace thus designed was measured at high pressure and temperature using two methods: (1) by measuring the thermal expansion of NaCl contained in the sample chamber; and (2) by observing the area of molten Pb which was mixed with the NaCl. Both of these measurements were performed by high-pressure and temperature in situ x-ray techniques. It was confirmed from these experiments that the furnace has a homogeneous temperature distribution and the difference in temperature is less than 5 °C when the center is about 600 °C. The homogeneity in temperature is nearly constant, even when the thermal conductivity of the sample is decreased by two orders of magnitude.