Abstract: A spacer block (3) for an elongated substrate (1) on the inside of an elongated tube (2) comprises an internal ring (3a) which surrounds the elongated material, an external ring (3b) which is surrounded by the elongated tube (2), where the outside diameter of the internal ring (3a) is smaller than the inside diameter of the external ring (3b), and the internal and the external ring (3a, 3b) are interconnected by at least three spoke-type elements (3c) made of fiber material, which are uniformly spaced around the circumference.

Abstract: The conduit system is comprised of a corrugated inner and a corrugated outer tube with a helical spacer in between, the spacer being comprised of intertwined, stranded and/or, braided ceramic fibers.

Abstract: The interior of a tube provided for low temperature operation is shielded from the exterior through a plurality of metal ribbons helically looping around the tube in an intertwined relationship and each carrying a welded on conduit for low temperature liquid whereby one of these conduits serves as a primary or outgoing conductor, and the two others serve as return paths; suitable spacers are provided to position the system in a concentric relation; inner and outermost tubes are preferably corrugated and the immediate interior of the outermost tube is filled with superinsulation.