TABLE OF CONTENTS This chapter describes the basic concepts, philosophies, and techniques used in modeling and analyzing cryogenic systems for space. Modeling and analysis of cryogenic thermal systems differ significantly from modeling and analysis of ambient thermal systems; however, the processes share many methods, equations, and components. Thus the chapter refers frequently to Volume I of this handbook, [20.1] which discusses many basic analysis concepts in more detail. Because infrared (IR) sensor instruments are the most common space cryogenic application, discussions here concentrate on them. Many of the techniques described, however, are equally applicable to any other cryogenic space system.
For any space application, thermal system design and modeling is important to the overall system success. However, the thermal system's importance is amplified significantly for cryogenic systems. Conventional thermal systems (those near room temperature) are often associated with the spacecraft bus, but cryogenic systems are usually integral to the instruments they serve and to the payload, and they are almost always enabling for instrument operation. In addition, an instrument's performance is usually extremely sensitive to the performance of the cryogenic system. Small cryogenic system degradations or inadequacies of fractions of a degree, for instance, can render an IR sensor inoperative.
The importance of the cryogenic system makes cryogenic system thermal modeling and analysis critical to overall program success. Also, just as the cryogenic...
