Excerpted from the preface of Cryostat Design: Case Studies, Principles and Engineering
Cryostats are technical systems that maintain equipment or cryogenic liquids at cryogenic temperatures. As such, they are one of the fundamental building blocks of cryogenic systems. Examples of cryostats include: the magnet cryostats that comprise the majority of the Large Hadron Collider (LHC) at CERN, spaceborne cryostats containing sensors operating below 1 K, MRI cryostats found in most large hospitals and large cryogenic liquid storage vessels.
Cryostats that contain superconducting radio frequency cavities are frequently referred to as cryomodules, while cryostats whose principle function is to store cryogenic fluids are also referred to as dewars. Cryomodules and dewars are also covered in this work. The proper design of cryostats requires knowledge of many disciplines including: cryogenic properties of materials, heat transfer and thermal insulation, instrumentation, safety, structures and seals. One of the best ways to learn about cryostat design is to study the design choices and resulting performance of previous designs.
This book provides such a review. It is edited by John Weisend II, a senior scientist and group leader at European Spallation Source ERIC and CSA chairman, and includes contributions from Weisend’s colleagues and researchers from CERN, Fermi National Accelerator Laboratory (CSA CSM), NASA Goddard Space Flight Center, GE Global Research and Thomas Jefferson National Accelerator Facility (CSA CSM).
It begins with an introduction to the principles of cryostat design, including practical data and equations. A series of case studies on existing cryostats follows, presenting the design choices behind various cryostats and the resulting performance of each. The cryostat examples used were chosen to cover the wide range of cryostat applications and the authors of each case are leading experts in the field, all of whom participated in the design of the cryostats being described.
Chapters 2 and 3 are case studies involving superconducting magnets for large particle accelerators. Due to the large numbers of magnets required in these cases, low heat leak, reliability and cost are key requirements. Chapter 4 describes a one-of-a-kind spaceborne dewar system whose requirements are very different than those of accelerator cryostats.
Chapters 5 and 6 describe cryomodules that contain superconducting RF cavities in particle accelerators. As readers will discover, there are two broad families of these cryomodules (segmented and continuous), with different design drivers and approaches. Taken together these chapters describe a total of six different cryomodules and provide an overview of the evolution of cryomodule design from the 1980s to the 2010s.
Chapter 7 presents special topics in cryostat design, many of particular importance for the MRI magnet cryostats that provide the examples, but which are broadly valuable for all cryostats. A cryostat design for very low (50 mK) temperatures is described in Chapter 8. In addition to the lower temperatures, this cryostat has unique material requirements due to the need to keep the radioactive background of the associated experiment as low as possible.
Transfer lines connect cryostats and are a type of cryostat themselves. Transfer line features, an overview of major transfer line systems and a detailed case study of a transfer line are found in Chapter 9. The final chapter provides a summary by listing guidelines for successful cryostat design, while extensive references throughout provide sources of further information.