MIRI Cooler System Design Update
MIRI Cooler System Design Update
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发表时间：
2008-05
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通讯作者：
M. Petach;D. Durand;M. Michaelian;J. Raab;E. Tward
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作者：
M. Petach;D. Durand;M. Michaelian;J. Raab;E. Tward
詹姆斯·韦伯太空望远镜（JWST）的中红外仪器（MIRI）需要通过主动冷却器为SiAs焦平面提供6 K的冷却。四级冷却器包括：位于JWST航天器总线上的三级脉冲管预冷器、焦耳-汤姆逊（J-T）循环器和上一级回热器，以及位于远程仪器模块上的末级回热器和6 K J-T膨胀器，在航天器和仪器之间有一条18-22 K的12米往返线路。自从我们上一次关于冷却器设计的报告以来，JWST计划已经对总体热设计进行了设计变更，包括由戈达德航天飞行中心（GSFC）在MIRI光学模块周围增加主动冷却热屏蔽，以提高总体热效率，从而增加冷却器升力能力和预期热负荷之间的裕度。这种变化将一部分热负荷从6 K冷却器阶段转移到18-22 K阶段。满足在18-22 K下增加的热负荷和实现在6 K下从降低的负荷中获得的益处需要在不同的一组操作点下操作冷却器。在本文中，我们报告了冷却器的操作和设计所需的变化，并证明了基本设计有能力满足新的要求。
The Mid Infrared Instrument (MIRI) for the James Webb Space Telescope (JWST) requires cooling at 6 K for the SiAs focal planes, provided by an active cooler. The four stage cooler consists of: a three-stage pulse tube precooler, Joule Thompson (J-T) circulator and upper stage recuperators, located on the JWST spacecraft bus, and the final stage recuperator and 6 K J-T expander, located at the remote instrument module with a 12 meter round trip line at 18-22 K between the spacecraft and instrument. Since our last report on the cooler design, the JWST program has made design changes to the overall thermal design, including the addition by Goddard Space Flight Center (GSFC) of an actively cooled thermal shield surrounding the MIRI Optical Module to increase the overall thermal efficiency and thereby increase the margin between the cooler lift capability and the expected heat loads. This change shifts a portion of the thermal load from the 6 K cooler stage to the 18-22 K stage. Meeting the increased thermal load at 18-22 K and realizing the benefit from the decreased load at 6K requires operating the cooler at a different set of operating points. In this paper, we report on the required changes to the cooler’s operation and design, and demonstrate that the basic design has the capacity to meet the new requirements.