Heat transfer by radiation to surfaces at low temperatures

Abstract

A study of the transfer of heat between the walls of vacuum vessels is made. It is shown that the heat transferred from the outer wall at ordinary temperature to the inner vessel at 90° K is greater than would be expected from the reflectivity of the inner wall, as estimated from its electrical conductivity. The apparent emissivities at 90° K of copper, silver, gold, tin, brass, aluminium, steel and graphite were determined. It was found that a freshly reduced smooth surface of copper was more efficient in diminishing the heat transfer than a highly polished surface.