Low Maintenance, Low Cost Cryocooler for HTS Degaussing Systems

High Temperature Superconducting (HTS) cables offer major advantages over the conventional copper cables currently used to reduce the magnetic signatures of Navy ships. A degaussing system utilizing HTS cables would be smaller, lighter, and cost less to install than current systems. However, the cryogenic operating temperature of the HTS cables requires the use of a cryogenic refrigerator (cryocooler). Existing, commercially available regenerative cryocoolers suitable for use with an HTS degaussing system have a number of disadvantages including limited cooling capacity (requiring the use of more units than ideal), system size, relatively large and fragile cold heads, noisy operation, and the need for periodic maintenance. The objective of the currently proposed effort is to evaluate the potential for developing a large capacity reverse turbo-Brayton cryogenic refrigerator that would have lower life cycle costs, require less maintenance and be smaller in size than an equivalent cryocooler system based on COTS technology. In Phase I, we will develop a preliminary system design to estimate performance, size, and cost, and we will develop a potential integration concept with the rest of the HTS degaussing system. In Phase II, we will fabricate key components of the cryocooler and demonstrate them at the system level.