Indian Journal of Cryogenics

The development of cryopumps with higher pumping speeds is needed for fusion related applications. Towards this goal, pumping speeds of different Activated Carbons (ACs) have been studied by adhering them on cryopanels mounted on two stage Cryocoolers, to arrive at the best pumping speed. The standard American Vacuum Society (AVS) procedures have been adopted in pumping speed measurements. Although cryopanels fabricated with Knitted Carbon Cloth (KCC) have higher pumping speeds in the specific pressure range of interest suitable for fusion applications, their sorption capacities are quite low, due to the lower masses of ACs. On the other hand, Cryopanels with pelleted ACs are found to perform better than KCC cryopanels, due to the increase mass of ACs and hence tolerate higher gas loads compared to KCC cryopanels. The present studies indicate the need for larger mass of ACs in cryopanels for better pumping speed with higher sorption capacities.