Thermally shielded superconductor current lead

A superconductor current lead assembly, comprising:

• a tube having a sealed end and an open end, in use said open end of said tube being at least partially submerged in a cryogenic liquid contained within a bath chamber, and
• a superconductor lead element at least partially contained within said tube, in use a portion of said superconductor lead element contained within said tube extends below a liquid level of the cryogenic liquid in the bath chamber,
• said tube being sealed other than at said open end such that cryogenic liquid is substantially prevented from entering said tube, such that said tube thermally shields said superconductor lead element such that in use said portion of said superconductor lead element is maintained at a temperature higher than a temperature of the cryogenic liquid, said sealed end preventing leakage of cryogenic fluid out of said sealed end,
• said tube including a connector for connection to a device submerged in said cryogenic liquid, said tube acting as an electrical by-pass of said superconductor lead element upon failure of said superconductor lead element.

A system cooled by a stratified liquid cryogen system, comprising:

• a dewar vessel defining a bath chamber for containing a cryogenic fluid,
• a superconductor current lead assembly including a tube having a sealed end and an open end, said open end of said tube in use being at least partially submerged in the cryogenic fluid, and a superconductor lead element at least partially contained within said tube such that in use a superconducting portion of said superconductor lead element contained within said tube extends below a fluid level of the cryogenic fluid in the bath chamber,
• said tube being sealed other than at said open end such that cryogenic fluid is substantially prevented from entering said tube, such that said tube thermally shields said superconductor lead element such that in use said portion of said superconductor lead element is maintained at a temperature higher than a temperature of said cryogenic fluid,
• a device located within said bath chamber for submersion in the cryogenic fluid, and
• a connection electrically connecting said high temperature superconductor current lead assembly to said device.