Measurement of thermal conductivity of materials down to 4.5 K for development of cryosorption pumps

Cryosorption pumps belong to the class of entrapment or capture vacuum pumps and they retain the gas molecules by sorption and / or by condensation on its internal surfaces. An important aspect in their development is the proper adhesion of the activated carbon granules onto the metallic panel and their cooling to the lowest possible temperature by using high thermal conductivity adhesives for adhering the activated carbons. Hence, the thermal conductivity data of the select adhesives and activated carbons down to 4.5 K are quite essential, but they are not available in open literature. Towards this, an experimental setup has been developed to measure the thermal conductivities of samples with high or low thermal conductivities from 300 K to 4.5 K, with liquid helium using a Janis SuperVariTemp cryostat. This paper presents the details of the experimental setup and the results of our studies on (i) standard samples and (ii) epoxy based adhesives samples. The above studies will enable to make the right choice of adhesives for the development of cryosorption pumps. (paper)