Conceptual Design and Development History of the MIRI Cryocooler System on JWST

The Mid Infrared Instrument (MIRI) of the James Webb Space Telescope (JWST) is a demanding application for the use of space cryocoolers. Used to cool JWST’s ~100 kg MIRI instrument down to 6 K, the MIRI Cryocooler is critical to enabling the mission’s long-wave infrared science associated with studying the post-Big Bang early formation of the Universe. The selection and design of MIRI and its cryocooler system started with the successes and limitations of JWST’s precursor, the Hubble Space telescope. Planned as the follow-on to Hubble, JWST abandoned Hubble’s astronaut-accessible low-Earth orbit for a colder and better-science environment a million miles from Earth. Targeting for this L2 location meant no servicing missions would be possible, and reliability and life would be critically important. JWST’s increased size, with a 6.5 meter diameter mirror, meant significant deployments would be required post launch to allow the observatory to unfurl from its launch-vehicle shroud and separate the cold telescope from its hot and noisy spacecraft bus. The MIRI cryocooler system met these mission constraints by positioning its dual compressors inside the spacecraft bus, while the MIRI instrument and the cryocooler’s cold-end is positioned 10 meters away in the Science Instrument Module. Accommodating the 1.3-m deployment of the telescope away from the spacecraft and minimizing any vibration transmitted up the connecting refrigerant lines was a driving requirement on the cryocooler system. Providing MIRI’s large refrigeration load at 6 K, while simultaneously cooling MIRI’s 18 K radiation shield required an allnew hybrid Pulse Tube/Joule-Thomson cryocooler. This paper provides an overview of the overall MIRI cryocooler system as it evolved to meet these demanding JWST requirements over its nearly 20-year development history. During this period it drew heavily upon ongoing Pulse Tube cooler developments as well as a history of earlier hybrid J–T cryocooler technologies.

搜集汇总

背景与挑战

背景概述

该数据集总结了詹姆斯·韦伯空间望远镜（JWST）中红外仪器（MIRI）低温冷却器系统的概念设计和近20年的开发历史，重点介绍了其用于冷却MIRI至6K的关键作用，以及为满足JWST任务需求而设计的混合脉冲管/焦耳-汤姆逊冷却器技术。