Studies on activated carbons towards the performance improvement of cryosorption pump

Abstract

Cryosorption pumps are the only possible solution to pump helium gas in Tokamak. In cryosorption pump, due to weak van der Walls forces the adsorbate gas molecules are held by the adsorbent well above the boiling point of the adsorbate gas. Therefore selection of best adsorbent is of utmost importance for the optimum performance of cryosorption pump towards the pumping of helium gas. In this paper, we report the pore size distribution and surface area of different activated carbon adsorbents to arrive at the best activated carbon for the development of cryosorption panel. Also probably for the first time, an attempt has been made to estimate the thermal conductivity of liquid helium based small size prototype cryopanel. The thermal conductivity of the panel has been improved by mixing the fine aluminium powder as filler to the epoxy adhesive. From the experimental studies it is found that KCC/IIS01 is the best adsorbent towards the development of cryosorption pump. Mixing of 35% fine aluminium powder as a filler to the epoxy adhesive improves the thermal conductivity of the cryopanel by ~14% and in turn enhances the pumping speed by ~2.35 times as reported in our earlier studies.