Cryopump development at Institute for Plasma Research, India

Development of sorbent coated cryopumps done at Institute for Plasma Research, Bhat, Gandhinagar is now finding application in Fusion and space research programme of the country. Three cryopumps of 400 mm opening, developed by IPR are installed and in operation at ISRO, SAC, Ahmedabad on cryovac chambers. The cryopump developed for SST-1 machine is tested for its performance. These cryopumps are developed to pump water vapour, and nitrogen gas at liquid nitrogen temperature based on physic-sorption process. It has a liquid nitrogen bath at its centre. Its cryopanels are coated with coconut shell charcoal and get cooled by conduction as they are mounted on the bath. It differs from the existing commercial cryopumps in a way that it does not require any compressor, it can operate in absence of electrical power. Once installed it requires less maintenance as it has no moving parts. The 400 mm opening cryopump developed for ISRO provides pumping speed of ∼5000 l/s for Nitrogen and about ∼16000 l/s for water vapor with a pumping capacity of > 6000 mbar-l. This papers covers the details of development of cryopumps at Institute for Plasma Research from concept to product. (author)