As the name implies, closed cycle systems recirculate a fixed volume of gas to provide cooling to the sample mounting stages, and no gas is added or removed during operation.

Janis Closed Cycle Refrigerator (CCR’s) utilize the Gifford-McMahon thermodynamic cycle, based on the controlled compression and expansion of helium gas. A compressor is used to provide the high pressure helium gas needed for the cycle. Flexible metal gas lines deliver the compressed helium gas to the refrigerator, and return the low pressure gas to the compressor for recirculation. The refrigerator includes two cold stages, one for cooling the sample and one for cooling a radiation shield that surrounds the sample.
CCR systems are available in two general configurations, sample in vacuum (cold finger), and sample in exchange gas (top loading). Within these broad categories, models with optical, non-optical, compact and sub-compact designs are available, some with temperature range to 475/700 K. Janis also offers systems for specific applications, including Mössbauer spectroscopy, VSM, Resistivity and Hall Effect measurements.