Small Helium Liquefiers Using 4 K Pulse Tube Cryocoolers Available to Purchase

Two small helium liquefiers using 4 K pulse tube cryocooler have been developed and commercialized at Cryomech, Inc. Model PT405 and PT410 pulse tube cryocoolers used for the liquefiers have cooling capacities of 0.5 W and 1.0 W at 4.2 K respectively. One distinctive advantage of the pulse tube liquefiers is efficient precooling of helium gas to be liquefied with the 1^st stage heat exchanger and the 2^nd stage regenerator of the cold head. The liquefier with the PT405 liquefies helium from room temperature at a rate of 7.2 Liter/day for 4.6 kW power input. The liquefier with the PT410 has a liquefaction rate of 14.0 liter/day for 8.0 kW power input. The helium liquefiers have been used for a few challenging applications to liquefy and re‐condense helium.