Cryostat

A cryocooler is a mechanical refrigeration system designed to cool applications to cryogenic temperatures. Cryogenic temperatures are typically defined as being below approximately 123 K (-150°C or -238°F), where many physical phenomena begin to change rapidly from room temperature behaviors, and new phenomena become significantly important. Therefore, the field of cryogenics often involves a whole set of discipline-specific skills, operational limitations, and testing methods associated with specific temperatures below this threshold. A special attribute of cryogenics is the science and engineering of achieving low temperatures, which is the development of cryogenic cooling devices—otherwise known as cryocoolers.
The working principle of cryocoolers is based on different cycles, including the Stirling cycle, pulse-tube, Gifford-McMahon, Joule-Thomson, and Brayton cycles. These cycles utilize different types of heat exchangers, such as recuperative and regenerative heat exchangers, to achieve cooling effects. The working fluid in cryocoolers is almost always helium due to its ideal gas properties, high thermal conductivity, and high specific heat ratio.
Cryocoolers have a wide range of applications, from MRI machines in hospitals, long-wave instruments on space telescopes, to night vision devices on the military battlefield. Cryocooler technology can provide this cooling, with the main types of technology including Stirling, pulse-tube, Gifford-McMahon, Joule-Thomson, and Brayton, all of which are focal points of interest at international cryocooler conferences.