Research on rapid refrigeration and precise temperature control of cryogenic infrared mirror

The key points in the thermal control design of the infrared camera for rapid cooling were analyzed in detail according to the characteristics of opto-mechanical structure and the space heat flux. The open J-T throttling system is combined with the infrared opto-mechanical structure directly, which avoids the heat leakage of cold chain, and also improves the difficulty of design the low temperature optical coupling structure and flow field. According to the structure and material characteristics of infrared optical mirrors, the expansion cavity is designed inside the optical element to make it have the functions of the heat exchanger and the infrared optical mirror. The flow field of the optical path is optimized by CFD simulation to realize the effective distribution and rational utilization of the cooling capacity, and the high-efficiency thermal protection, thermal isolation and other temperature control technologies are used to reduce the loss of cooling capacity. A low-temperature optical system with two-stage J-T throttling heat transfer is designed, and the flow and heat transfer characteristics of low-temperature working medium after two-stage throttling are emphatically analyzed. The simulation results show that the temperature of optimized optical mirror can be reduced to 170Kwithin600s, and the overall temperature gradient can be controlled no more than 1K. This study will provide important research ideas and theoretical basis for refrigeration and thermal control of infrared camera with high response speed.