SITP’s Miniature Coaxial Pulse Tube Cryocooler
Dang, H. Z.
Wang, L. B.
Wu, Y. N.
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A single-stage miniature coaxial pulse tube cryocooler (PTC) has been developed in Shanghai Institute of Technical Physics, Chinese Academy of Sciences (SITP/CAS) to serve as a perfect substitute for an existing Stirling cryocooler for providing reliable low-noise cooling for an infrared detector system. The challenging work is the exacting requirement on its dimensions, which have to adapt to the given dewar. A 1.5 kg dual opposed moving magnet compressor is used to realize light weight and low contamination. A large filling pressure of 3.5 MPa and high operating frequency of up to 67 Hz are adopted to increase the energy density, which will compensate for the decrease in working gas volume due to the miniature structure. The miniature dimensions also limit the phaseshifting ability of the system when the inertance tubes act as the only phase-shifting mechanism. The simulation suggests that a second orifice would be helpful to achieve the desired phase relationship. In the practical development, the inertance tube, composed of two sections with different inner diameter and length, act as the only phase-shifter to realize a reliable system. When the cold finger diameter and length are 10 mm and 53 mm, respectively, the miniature PTC achieves 1.6 W of cooling power at 90 K with 65 W of electric input power. The no-load temperature of 64.5 K is achieved in about 7 minutes. The design approach and trade-offs are discussed, and the parametric studies and the performance characteristics are presented.