GB1254773A - Superconductive magnet construction - Google Patents

Abstract

1,254,773. Superconductor magnets. RCA CORPORATION. 5 May, 1969 [6 May, 1968], No. 22771/69. Heading H1P. In a superconductor magnet coil comprising a plurality of helically wound layers of superconductor ribbon, the ribbon is stabilized by a coating of normal metal the cross-sectional area of which is smallest in the layer subjected to the least magnetic field intensity and largest in the layer(s) subjected to the greatest magnetic field intensity. As shown, Fig. 2, the coil is wound on a flanged spool 10 of aluminium or stainless steel provided with insulating layers 16, 18 and 20. Copper shorting bars 22 are placed parallel to the axis of the spool and a layer of stabilized superconductor ribbon is helically wound on to the spool. An interlayer member 32 comprising a sheet 36 of normal metal sandwiched between two insulating films 34 is applied over the first winding layer. Further winding layers separated by interlayer members are then applied and the superconductor ribbons of the various layers are connected in series. The superconductor ribbon comprises a stainless steel core coated with a layer of Nb 3 Sn which is stabilized with a layer of a normal conductor such as silver or copper. The cross-sectional area of the normal metal layer of the ribbon used for each layer is selected in accordance with the magnetic field to which the layer is subjected when the complete coil is energized, being smallest in that layer subjected to the least magnetic field intensity. This enables the size of the coil to be reduced relative to a coil with constant stabilizing layer cross-section without loss of stability. The thickness of the normal metal sheets in the interlayer members may be similarly varied. The cross-sectional area of the superconductor layer of the ribbons may be constant or may be varied in the same manner as the normal metal layers. The conductors may have a circular crosssection, the core may be omitted, and there may be different numbers of turns in the various layers. A group of adjacent layers may be wound using conductors having the same dimensions, and the normal metal sheets in adjacent interlayer members may have the same thickness. The spool need not have flanges and may be of insulating material.