High performance cryogenic packaging for microwave applications of high temperature superconductors

For microwave applications employing high temperature superconductor (HTS) technology to be commercially viable, a high performance cryogenic package is essential. Design considerations to minimise the heat leaks from ambient through conduction along the electrical interconnects and through radiation from the package walls, to reduce the size and mass and to reconcile the physical characteristics of the wide range of materials used within the microwave module and cryogenic package are discussed. Fabrication, process and assembly techniques, which play an important role in determining the long-term reliability of any HTS system, are described. Two examples of the design of cryogenic packages, for commercial and military applications, with inherent mechanical and thermal integrity, high reliability and which do not require a regular maintenance regime are presented to illustrate the design techniques being developed.