Cryogenic temperatures are required in many areas of technology and research. In practice, several temperature ranges have emerged in which most applications lie and for which suitable chillers have been developed. These are the LN2 range at 77 K, the 10 K range, the LH range at 4.2 K, and the mK range.
SHI Cryogenics and APD Cryogenics, which was acquired in 2002, offer a comprehensive range of cryocoolers/refrigerators for the above temperature ranges. All models are operated in a closed helium circuit with no consumption of refrigerants and require only electrical power and cooling water or air for operation. These cryocoolers can be divided into two groups:
Gifford-McMahon (GM) coolers
In these coolers, an oscillating one- or two-stage piston takes over the transport of heat from the cold stations into the cooling medium (water or ambient air). The minimum temperatures of these coolers are 4 K, 6.5 K and 10 K (two-stage models) or approx. 40 K (single-stage models). Nominally, chiller maintenance is due every 10,000 hours of operation, although in most cases much longer run times can be achieved between maintenance. The piston (displacer) is driven by a motor or pneumatically, depending on the model. The GM coolers can be operated largely independent of position. The compressors required for the operation of the GM coolers are available in several performance levels and with water or air cooling.
Pulse Tube Coolers (PTC)
In pulse tube coolers, an oscillating gas column takes over the task of the displacer. Here, too, the heat is ultimately transferred from the cold station to the compressor cooling medium. SHI offers several pulse tube chiller models with a base temperature of 4 K at different power levels.
We offer the single and two-stage GM chillers with 6.5 K, 10 K and approx. 40 K minimum temperature.