ABSTRACT
Vacuum techniques are a mainstay of cryogenic heat management and cryogenic engineering. Vacuum technology is the central enabling feature of cryogenic engineering on Earth. As we understand that the temperature difference is the driver for heat flow, we know that vacuum is the necessary second line of defense against reducing the flow of heat. Good design is always the first line of defense in reducing heat conduction to a manageable level, but it is the vacuum enclosure or vacuum jacket that commands the overall design, look, and operational characteristics of the cryogenic system. Vacuum is necessary for the thermal isolation of cryostats, tanks, and piping to enable basic functionality of the system and control of the cryogenic fluid. Vacuum is essential for conducting many scientific measurements. Vacuum comes into play for a range of experimental physical and chemical processes. The word “vacuum” means the absence of matter, but the reality is always an approximation. Thus, the level of vacuum must be clearly defined and understood for each specific application.
