A 2K closed cycle cryogenerator

This is an original set up for a SIS mixer at 2 K from a 2-stage CTI (1020). A second closed helium compressor (CTI 350) provides high-pressure gas at the first exchanger (300-60 K); a second exchanger (60-12 K) cools HP gas. Then a JT decreases gas temperature down to 4.5 K. The liquid part of He-4 is transferred to the last stage which is pumped below 24 mm/Hg (2 K). An external knob and vacuum pump valve makes it possible to check the flow to the 2 K stage. The limit temperature on the last stage is 1.5 K. At 1.7 K, the available thermal power is 80 mW.