A HELIUM RE-LIQUEFIER FOR RECOVERING AND LIQUEFYING HELIUM VAPOR FROM CRYOSTAT

Abstract

We have developed a helium re‐liquefier to provide a solution for recovering and liquefying helium vapor from open‐loop helium cryostats. The helium re‐liquefier is designed to retrofit into the cryostat and form a closed helium loop for the system. The re‐liquefier employs a 4 K pulse tube cryocooler, model PT410, which simultaneously provides 39 W at 45 K and 1.0 W at 4.1 K on the 1st and 2nd stages respectively with a power input of 7.5 kW. The reliquefier can operate in two modes: reliquefying 100% room temperature helium vapor or recondensing and reliquefying two streams of 4.2 K and room temperature vapor at the same time. The reliquefier has a liquefaction rate of 14.2 L/day for the room temperature gas. It has a condensation capacity of recondensing and re‐liquefying up to 29 L/day.