Study On A High Frequency Two-stage Pulse Tube Refrigerator At 35k With A Cold Inertance Tube

Compared to G-M type pulse tube cryocoolers(PTCs), Stirling-type PTCs have the advantages of compact structure, light weight, high reliability, low vibration and non-maintenance. Compared to Stirling cryocoolers, the PTCs have the advantage of long life due to no moving parts at the cold head. Therefore, Stirling-type PTCs driven by linear compressors at room temperature are the potential cryocoolers which are suitable for detectors cooling in space application.35K is a very important temperature which used to cool the HgCdTe detector, and usually combine 85K for optics equipments cooling in space application. At the same time, in order to achieve the total Stirling structure for a 4 K Stirling-type PTC without precooling, we carry on the research of a high frequency PTC for 35K by the way of theory and experiment.1. A thermally coupled two-stage Stirling-type PTC at 35K with a cold inertance tube as the second stage phase shifter was proposed.Based on literature papers and theoretical analyse, a thermally coupled two-stage Stirling-type PTC was adopted for 35K refrigeration requirements. Based on the phaor mechanism of inertance tube, two inertance tubes as phase shifters for both stages respectively were used in this PTC system, in which one inertance tube was used at room temperature for the first stage, the other was put at the end of first stage PTC as so called cold inertance tube phase shifter. Based on the regenerator numerical code REGEN, the 500 meshes stainless steel was propsed as the best regenerative materials for the cold part of the second stage regenerator(RG22), which regenerative performance is better than lead sphere at 35K temperature range. Furthermore, the second stage regenerator geometry and operating parameters are chosen to optimize the cold part of the second stage regenerator(RG22) performance. The geometry of pulse tube, heat-exchangers and the cold inertance tube of the second stage were also given as detail. Finally, the analysis has shown that it is more thermodynamically efficient to use cold inertance tube as the second stage phase shifter than ambient approach.2. A two-stage Stirling-type PTC system at 35K was designed, manufactured and. established.Based on theoretical calculation, a designed two-stage Stirling-type pulse tube cryocooler system for 35K with cold inertance tube at the second stage was manufactured and established.3. Experiments on the two-stage Stirling-type PTC at 35K were carried out, and the experimental results were agreed quite well with the theoretical calculation.The no load temperature of 23.7K and 0.57W at 35K were obtained, these experimental results were agreed quite well with the theoretical calculation.