Duct system for low-temperature fluids and thermally isolated electrical conductors

Claim 2

A cryogenic conducTor comprising: at least one substantially continuous inner duct of a thin-wall collapsible and flexible material at room temperature, said inner duct extending over the length of the conductor; an intermediate shell spacedly surrounding said inner duct and defining a low-vacuum chamber therewith; an outer shell spacedly surrounding said intermediate shell and defining a high-vacuum space therewith; means for subjecting said material to a pressure differential serving to maintain said inner duct erect; at least one electrically conductive current-carrying member extending through said inner duct; said intermediate shell enclosing a plurality of inner ducts of such material with current-carry members passing through at least some of said inner ducts; spacers of I profile received in said intermediate shell and formed with respective arms each engaging one of said ducts for holding said ducts apart; a high-vacuum pump capable of developing a suction of at least 10 5 torr communicating with the interior of said outer shell; a plurality of labyrinth seals along the exterior offset ducts subdividing the interior of said intermediate shell into a plurality of axial sections, each of such labyrinth seals comprising a plurality of polytetrafluoroethylene disks hugging said ducts and fitting closely against said intermediate shell; respective suction means connected to each section for generating therein a suction between about 10 3 torr and 1 torr; and cooling means formed in said intermediate shell and connected with a coolant circulation source.

Claim 3

The conductor defined in claim 3 wherein said inner ducts are formed of polyethyleneterephthalate.