Method of producing a superconducting cable

A method of producing a superconducting cable, where a plurality of superconducting ribbons (4) are applied onto a preferably flexible tube (3), said ribbons being applied in one or more layers optionally separated by intermediate plastic layers, whereafter a protective layer (5) of textile or paper is optionally applied followed by a metal tube (6) serving as the innermost wall of a cryostate, and whereby a plurality of for instance helical spacers (12) are applied onto said metal tube (6) followed by a final outer metal tube (9) serving as the outermost wall of the cryostate, the opposing walls of said metal tubes (6, 9) defining an inner volume of said cryostate, said inner volume being evacuated, wherein one or more electrically semi-conducting layers are arranged on the innermost wall (6) of said cryostate, and that a number of film layers are inserted between the metal tubes (6,9) and preferably below the spacers (12), said number of film layers comprising electrically insulating layers and a predetermined number of film layers coated with a thin reflecting layer of metal, serving as equipotential surfaces and equitemperature surfaces.