超导SIS混频器空间应用发射锁定机构热胀特性测量研究

高灵敏度太赫兹探测模块(High Sensitivity Terahertz Detection Module, HSTDM)是中国空间巡天望远镜---巡天光学设施的后端模块之一, 其核心探测器采用可工作于10K温区的氮化铌超导SIS (Superconductor Insulator Superconductor)混频器. 超导SIS混频前端的锁定机构在力学和热学方面需相应的特殊设计, 以应对发射阶段的力学振动以及工作运行阶段的隔热要求. 为了确认在80K温区锁定机构与混频器前端有效分离, 针对超导SIS混频前端发射锁定机构所用特氟龙材料热胀特性, 开展基于低温LVDT (Linear Variable Differential Transformer)测量和标记划痕法测量以及两种测量方法交叉验证. LVDT实验测量结果表明特氟龙材料收缩率随温度变化与理论模型基本一致, 在80K测得材料收缩率为1.86%. 据此分析, 超导SIS混频前端锁定机构在\lk 80K温度下可与10K冷级的超导SIS混频前端实现有效分离.

Research on Thermal Expansion Characteristics Measurement of Launch Lock Mechanism for SIS Mixer's Space Application

The High Sensitivity Terahertz Detection Module (HSTDM) is one of the scientific payloads of the China Space Survey Telescope. The core of the HSTDM is the NbN superconducting tunnel junction SIS (Superconductor Insulator Superconductor) mixer, operating at temperature 10 K. The installation structure of the superconducting SIS mixer needs to be specially designed to cope with the mechanical vibration during the launch phase and the thermal insulation requirements during the operation phase. Material thermal expansion characteristics investigation based on the low-temperature LVDT (Linear Variable Differential Transformer) measurement and marking scratch measurement were carried out to confirm the design validity of the thermal expansion locking mechanism. The two methods are cross-verified. The LVDT experimental measurement results show that the shrinkage rate of Teflon material changes with temperature and meets the theoretical model. At the same time, we verified the LVDT results with the marking scratch method. Consistently, the shrinkage rate of the material is 1.86% at 80 K, so the Teflon front-end locking mechanism of the superconducting SIS mixer can achieve effective separation.