Experimental Research and Optimization of a 100 Hz In-line Type Pulse Tube Refrigerator in the 60 K Temperature Region

Currently, the demands on the operating temperature range and cooling capacity for the infrared detectors in space are growing rapidly, and the higher requirements are being placed on the light weight design of cryogenic refrigerators. With their compact structure, light weight, low noise and high operational reliability, high frequency pulse tube refrigerators are considered as ideal cold sources for the cooling infrared detectors. At home and abroad, there are few research on the pulse tube refrigerator with 100 Hz frequency in the 60 K temperature zones, while the current operating frequency is about 50 Hz. A miniature linear 100 Hz high-frequency 60 K pulse tube refrigerator is designed and developed to meet the temperature range and cooling capacity requirements of infrared focal plane arrays in the space applications. Using the Regen3.3 software, the key component—the regenerator—is optimized and analyzed. The effects of the regenerator's length, the mesh count of packing wire mesh, and the ratio of the layered filling on the loss of the regenerator and the coefficient of performance are obtained. Based on Sage software, simulations and optimizations are performed on the structural parameters of the pulse tube, the phase shifter, and other critical components within the refrigerator. The weight of the cold finger part is only 1.5 kg. In addition, the effects of operating frequency, water cooling temperature, and input power on the pulse tube refrigerator's performance are analyzed. The results show that the performance of the pulse tube refrigerator is optimal when the regenerator is filled with a 1∶1 mixture of 400-mesh and 635-mesh stainless steel screens. Compared to a single-stage inertial tube, the variable-diameter multi-stage inertial tube can significantly enhance the performance of the refrigerator. The experimental results show that, with an input electrical power of 300 W, the minimum no-load temperature achieved is 42.69 K. A cooling capacity of 7.4 W can be obtained at 60 K, and the relative Carnot efficiency of the system is 9.6%. These findings provide valuable reference for the design of small high-frequency pulse tube refrigerator operating in the same temperature ranges.