液氮温区高温超导滤波器的漏热分析

为在液氮温区工作的高温超导滤波器的制冷机冷源选型,基于Sage 10软件对超导滤波器件的冷却装置进行了漏热分析,仿真计算了铜线和同轴线的几何参数对传导漏热量的影响,以及真空罩、冷盘的尺寸和发射率对辐射漏热量的影响,并综合上述分析计算了超导滤波系统的总漏热量。在仿真计算中发现,信号线的导热和真空罩中冷盘的辐射漏热在系统总漏热量中起主导作用。仿真计算结果表明,通过增大信号线长度、减小信号线直径的方式可将信号线漏热量降至0.72 W,约为初始导热量的1/3。与此同时,冷盘表面采用抛光镀金的方式减小表面发射率,使辐射漏热量降至原来的2/3。根据模拟计算的最优结果,选择制冷量为3 W@77 K的制冷机作为高温超导滤波器的冷源。

Thermal analysis of high-temperature superconducting filter working at liquid nitrogen temperature

In order to choose a suitable cryocooler for high-temperature superconducting filter working at liquid nitrogen temperature,the heat leakage from the cooling system of superconducting filter has been studied based on Sage 10 software.The effect of geometrical parameters of copper lines and co-axial lines on thermal conduction and the effect of size and emissivity of vacuum chamber and cold plate on thermal radiation were simulated.The total heat leakage of superconducting filter system was calculated combining with the above analysis.It was worth noting that both the heat leakage from thermal conduction of signal lines and the radiant heat leakage between vacuum chamber and cold plate play an important role in total heat leakage.The calculations showed that the heat leakage of signal lines could be decreased to 0.72 W,about 1/3 of initial heat leakage,by means of increasing the length and decreasing the diameter of the signal lines.Meanwhile,the cold plate surface was gold-plated polished to reduce emissivity,which reduced radiant heat leakage to 2/3 of initial value.According to the optimal result of simulated calculation,the cryocooler with the cooling capacity of 3 W at 77 K was selected as the cold source of high-temperature superconducting filter.