Design, fabrication, and assembly of a hollow-core fiber-based micro cryogenic cooler

One of the smallest Joule Thomson (J-T) micro cryogenic coolers (MCC) utilizing a hollow-core fiber-based heat exchanger (HX) is designed, fabricated, assembled and tested. Techniques that control mask material etching are developed to fabricate a multi-layer silicon structure on HX-coupling manifolds. A segmental metal coating is applied on the fibers and the capillary for solderable areas and reduced radiation and conduction heat transfer. With 16:1 pressure ratio mixed refrigerants, a 140 K stable temperature and 76 K transient temperature at cold head are demonstrated.