Janis 4K Cryocoolers
4 K cryogen-free closed-cycle refrigerators
4 K cryocoolers allow you to cool samples, devices, and/or equipment without the inconvenience and expense of liquid helium. They can be applied to a broad range of applications in both research and industry. Some typical uses include materials research, superconductivity, cryopumps, shield cooling, and helium recondensing.
Janis Research offers a variety of 4 K cryocoolers – see the range here
For more information please visit Lake Shore Cryotronics
Two-stage Gifford-McMahon (G-M) refrigerator systems have been in widespread use for several decades. Room temperature helium gas is first compressed and then supplied to the refrigerator via flexible gas lines. The compressed helium is cooled by expansion and provides cooling to two heat stations on the refrigerator. After cooling the refrigerator, the gas is returned to the compressor to repeat the cycle.
Pulse tube (PT) refrigerator systems use a similar compression/expansion cycle but eliminate the moving regenerator found in G-M cryocoolers. PT cryocoolers often have reduced vibration levels at the vacuum interface flange as compared with G-M systems. See the three main differences between PT cryocoolers and G-M cryocoolers.
Sumitomo Heavy Industries (SHI) 4 K cryocoolers are available in both modified G-M cycle and PT configurations, employing rare-earth heat exchanger materials. These materials retain useful heat capacity to temperatures below 4 K, resulting in base temperatures previously unobtainable in a two-stage cryocooler.
Is a 4 K cryocooler economically practical?
Prior to the introduction of 4 K cryocoolers, liquid helium was most commonly used to cool equipment and experiments to 4 K. The following chart shows the operating cost of a typical liquid helium-cooled apparatus (not including storage Dewar evaporative losses). In some cases, the entire cost of a 4 K refrigerator can be recovered in the first year!