大面阵红外焦平面杜瓦冷指支撑结构设计

空间红外相机为提高成像质量，采用脉冲管制冷机对大面阵红外探测器进行制冷和杜瓦封装，形成杜瓦组件，使探测器工作在深低温环境下。冷指与热端之间仅靠脉冲管的薄壁结构连接，径向支撑刚度偏低，无法承受卫星发射阶段的振动，需对冷指增加支撑结构；但为提高制冷效率，又需要尽量增大连接探测器的冷指与制冷机热端之间的结构热阻，以减少结构间漏热。传统的方案是在冷指与热端之间增加金属支撑柱，但该结构会带来附加的漏热，且因为连接刚度较大，会由于装配及加工误差在脉冲管焊缝处产生较大的结构应力，影响组件性能。提出一种基于玻璃纤维束的冷指支撑结构，利用玻璃纤维束的高抗拉刚度及低抗弯刚度提高冷指径向支撑刚度的同时减小其在轴向上的结构应力；同时，玻璃纤维束的超低导热系数和小截面面积可以极大的提高结构热阻，显著减小附加漏热。与传统方案相比，玻璃纤维束支撑加强结构在提高冷指支撑刚度同时，将冷指与热端之间的结构热阻增大为原来的3 730倍，解决了冷指支撑加强结构既要求抗振性能好、又要求漏热小的难题，可适用于各种类型的大面阵红外探测器的杜瓦冷指支撑结构。

Cold head supporting structure of Dewar used in large infrared focal plane

To improve the imaging quality, a pulse tube cryocooler is used in the remote sensor, and it is installed in the Dewar assembly to make the infrared focal plane work in very low temperature. The thermal resistance between the cold head and the heat head should be big enough to improve the refrigeration efficiency of the pulse tube cryocooler. The thin-walled pulse tube connects the cold head and the heat head, and its radial support stiffness is too low to bear the vibration of satellite during launching. The traditional scheme is to add metal pole support structure, but the structure will bring additional heat leakage and the thermal deformation caused by the temperature difference of metal pole structure will cause the detector deformation, which will affect the imaging quality. A glass fiber support structure was proposed. The glass fiber had the advantages of high tensile modulus, low thermal conductivity and very small area, and with reasonable position design this structure will improve the radial support stiffness and reduce the heat leakage. Because of the characters of low bending stiffness, the thermal deformation cannot pass to the detector. Compared with the metal pole support structure, the thermal resistance of glass fiber support structure increases by 3 730 times, and solves the problems of high vibration resistance and low heat leakage.