Indigenous development of a table top batch liquefaction for nitrogen using pulse tube crycooler

Cryogenic recondensation devices present considerable challenges towards condensing helium in systems such as MRI, NMR and SQUID cryostats etc. Normally refilling of cryogens is costly and also troublesome. To replace the standard refilling system, there is a need of small scale recondensing system. In a typical recondensation system, the evaporating gas is initially pre-cooled by the cooling power of the first stage cold head. Subsequently, it is passed on to the second stage cold head, where a special heat exchanger is mounted with large surface area for cooling. The gas when passing over this cold surface gets condensed into a liquid and returns back to the cryostat dewar. This paper presents the design and development of a simple experimental setup for batch liquefaction of nitrogen and is based on the two stage pulse tube Cryocooler already developed in our laboratory. The details of the system and the preliminary experimental results are presented here. This setup serves as a pre-runner for our subsequent development of re-condensation system for helium gas.