由于长焦距相机中支撑桁架的温度变化会降低光学系统成像质量, 本文研究了空间相机支撑桁架的热控设计。根据某高分辨相机的结构参数、光学系统对支撑桁架温度的要求及卫星的轨道参数分析了桁架杆的吸收外热流并确定了加热功率; 讨论了桁架热平衡公式, 并确认桁架杆的轴向温差主要与桁架杆加热片功率和加热片粘贴位置有关。在对桁架杆简化数学模型理论分析的基础上, 得到了杆的温差方程, 进而提出两种满足支撑桁架精确控温的热设计方法: 增大加热片面积和增加杆的等效导热率。实验证明了新型导热材料PGS(Pyrolytic Graphite Sheet)可以很好地满足支撑桁架等效导热率及轻型化的要求, 使用0.076 mm厚的PGS时, 可以将支撑桁架的轴向温差由7.9℃减小为0.83℃, 且每根桁架杆质量只增加12 g。最后, 通过热分析模型进行仿真实验, 证明了理论分析的正确性, 通过对桁架杆温差测量试验和热真空试验, 验证了仿真分析结果和PGS的空间适应性。 得到的结果证明了本文提出的空间桁架的精确控温方法是适用且有效的。

As the changed temperature of truss structure in a long focus camera will effect the image quality of an optical system, this paper explores the thermal design of supporting truss of the camera. First, the absorbed heat flux and heating powers of a truss rod were analyzed based on the temperature limit requirement of the optical system and the orbital parameters of the satellite. According to the analysis of thermal balance equation, it points out that the temperature difference of the truss is mainly determined by the heating power and arrangement of the heaters. Then, through the theoretical analysis of a simplified mathematical model of the truss, the temperature difference equation of supporting truss was derived, and two thermal control methods including increasing heater areas or increasing the effective thermal conductivity of the truss were presented. A new kind of material named Pyrolytic Graphite Sheet(PGS) was proved to be a candidate that can well satisfy the design requirements of increasing thermal conductivity and lighting the weight of supporting truss. On the calculation,it shows that the temperature difference has decreased from 7.9℃ to 0.83℃ with the mass of each truss increasing only 12 g by using 0.076 mm thick PGS. Finally, through the thermal vacuum test and temperature difference measurement test, it demonstrates that the analysis and simulation is valid and the PGS can withstand vacuum and temperature changes under the test conditions. The method presented in this paper is practical and effective.