Flexible Cryostat for Superconductors

In order to realize the benefits of the superconducting equipment needed to improve the national electrical distribution infrastructure, high temperature superconducting (HTS) wires must be maintained at temperatures well below ambient. To economically achieve and maintain these temperatures, further development in thermal insulation systems (cryostats) is needed. Three reliability issues associated with existing cryostats that use stainless steel corrugated cylinders have been identified: (1) loss of vacuum integrity during or just after manufacture ¿ micro-cracks can develop in the corrugated metallic tubes due to excessive hydrogen gas content, resulting in hydrogen embrittlement and the loss of vacuum, (2) cryostat damage during installation ¿ cryogenic hardware can be damaged during the pulling of the cable in the cryostat, generating small leaks, (3) degradation in service ¿ from out-gassing and voltage gradients between the inner and outer tubes. This project will demonstrate the use of new flexible plastic materials for the outer two cable cylinders instead of corrugated stainless steel. The new material has the potential to improve on all of the above issues and also reduce the life-cycle costs of the cryostat system. The resulting cable can be made interchangeable with existing high temperature superconductor (HTS) cabling and system interfaces. Commercial Applications and other Benefits as described by the awardee: In addition to the application to the electrical grid, the new material should be able to satisfy the vacuum insulated piping (VIP) requirements for an underwater transfer system for liquefied natural gas (LNG).