Low-power cryocooler survey

A cryocooler survey was performed on data of 235 cryocoolers, with cooling powers below some tens of watts and operating between 4 DegK and 120 DegK. The state-of-the-art is discussed and trends are studied on cooling performance, mass and size, cost, lifetime and reliability. The data were compared with earlier surveys to explore historical trends. Improvements in cooling performance were mainly in 80 DegK cryocoolers, an increase in efficiency by about a factor of 5. Coolers did not reduce in size significantly. Main redn. was in 80 DegK coolers because of the higher efficiency. In the survey, cost is related to input power, cooling power and operating temp. Cost development is considered and related to learning curves. Since the mid-90s, the lifetime of Stirling-type cryocoolers has increased by one order of magnitude from typically 0.5 to 5 yr or more. The confusion that exists on the term reliability is discussed. [on SciFinder (R)]