Micromachined cryogenic coolers for cooling low-temperature detectors and electronics

Vibration-free miniature cryogenic coolers are relevant to a wide variety of applications, including cooling of detectors in space missions, low-noise amplifiers and superconducting electronics. For these applications, the cryogenic system (cooler plus interface) should be small, low-cost, low-interference and above all very reliable (long-life). A cold stage based on micro-electro-mechanical systems technology was designed and prototypes were realized and tested. This cooler operates on basis of the Joule-Thomson effect. A design aiming at a net cooling power of 10 mW at 96 K and operating with nitrogen as the working fluid was optimized and measures 28 mm times 2.2 mm times 0.8 mm. It operates with a nitrogen flow of 1 mg/s at a high pressure of 80 bar and a low pressure of 6 bar. The design and fabrication of the coolers is discussed along with experimental results.