Experimental study and infrared detector application research of micro miniature refrigerators

The MMR（Micro Miniature Refrigerator）is a novel Joule-Thomson cryocooler manufactured by micro-machining technologies, its axial length is significantly shorter than traditional Joule-Thomson cryocoolers commonly employed in infrared detectors. MMRs can greatly reduce the size of infrared detectors upon successful implementation. However, contemporary MMR products encounter challenges such as relatively low cool-down rates, cooling power, and structural strength. To address these issues and enhance the cool-down performance of the MMR for effective application in infrared detectors, a calculation model describing flow and heat transfer besides working characteristics of the MMR is proposed and verified. MMR prototypes are fabricated and experimentally studied. Building upon theoretical analysis and experimental findings cooling performance enhancement methods including transitioning the MMR material from glass to metal and modifying the structure and channel patterns of the MMR are introduced, the cooling performance of the MMR is thus greatly improved. Furthermore, an integrated design incorporating an MMR into an infrared detector is proposed, the axial length of this infrared detector is reduced by 65.3 % compared to conventional infrared detectors. And the MMR is further enhanced to adapt the working conditions in infrared detectors, 60.9 MPa working pressure and 38 s cool-down time is achieved, the cool-down requirements of infrared detectors is satisfied. Notably, the proposed MMR and infrared detector design in this paper exhibit technical advantages over similar products reported in the literature.