Cryogenics, a term commonly used to refer to very low temperatures, had its beginning in the latter half of the 19th century. Traditionally, this field is separated from Cryogenic Engineering and Low Temperature Physics (LTP). Cryogenic engineering is concerned with the design and development of low-temperature systems and components, while low temperature physics is more related to the fundamental research of material or fluid properties. This book discusses some recent findings and developments as well as gives an outlook on the fields of helium cryogenics and LTP. The main focus will be given to the helium cryogenics, though a smaller review is also presented for the fields of cryogenic energy storage facilities. Some future trends and R&D activities are also discussed. To orient the reader, the first four chapters are related to LTP, while the major part of the book is then devoted to helium cryogenics, for example, refrigeration techniques, cryostats, low temperature electronics, safety, etc.It should be particularly suited for advanced students, young researchers or engineers, who are intending to proceed with careers in helium cryogenics or LTP. However, the authors believe that the book will also be of value to experienced scientists, since it describes several very recent advances in experimental low temperature physics and technology, for example, ultra-low temperature technique and thermometry, as well as progress in helium cryogenics, such as heat transfer, cryostat designs for large facilities, and refrigerator developments. Extensive references are provided for the readers interested in the details of the cryogenic engineering advances. And last but not least, the authors hope that this book will widen the horizons of many without a solid state background, but with a general interest in low temperature physics and helium cryogenics.In attempting to cover such a wide field, a large degree of selection has been necessary, as complete volumes have been written on many topics which here have had to be covered in very few pages or less. It is inevitable that not everyone will agree with the present choice, especially if it is their own subject which has been discussed very briefly or not mentioned at all, and the editor accepts full responsibility for the selections made. The book is written at a level which should be followed by a university graduate in science or engineering, although, if their background has not included a course in cryogenic engineering, general or solid-state physics, some groundwork may be lacking.

Radar and communication systems play an important role in civil and military applications. They are always under development and new versions continually come to the market. Though the basic operation principles have stayed nearly the same over the last 100 years, new technology has allowed for advancements in the development of components, and new systems find specific applications. Superconducting materials are widely used, for example in motors, magnets, cavities, and transformers, and are sometimes also used for typical components of radar and communication systems, like antennas, filters, and logical elements. Superconducting components significantly change the operation of whole systems, and thorough understanding of operational principles is of paramount importance for correct design. In this book, the recent developments of cryogenic receivers over the last 20 years are outlined. Special attention is given to the very specialised technologies, like Rapid Single Flux Quantum (RSFQ) logics, or electrically small active antennas based on SQUID/bi-SQUID/SQIF operational principles. The classical applications, like superconducting filters or cryogenically cooled Low Noise Amplifiers (LNA), are considered in detail. Though the book is considered as a review on recent developments of cryogenic receivers to facilitate an understanding of operational principles, many examples with estimations are given. The reliability of cryogenic receivers strongly depends on the mechanical and cryogenic designs, and many practical examples and solutions are also presented. Future trends or possible research areas are considered as well. This book will be helpful for graduate students as well as engineers working with cryogenic, radar and communication systems.