CS260184B1 - Superconducting magnet winding - Google Patents

Abstract

The purpose of the proposed) modification of the superconducting magnet winding is to improve the use of the properties of the superconducting conductor in the winding. The aforementioned improvement is achieved by inserting thermally and electrically conductive foils, preferably aluminum, between the individual layers of the winding. The superconducting magnet winding can find application in the construction of smaller and medium-sized superconducting magnets for research and industrial applications.

Description

The present invention relates to winding a superconducting magnet from ductile superconductors.

Until now, the windings of superconducting magnets have been produced using interlayer insulation from paper, glass fabrics, mylar foils. Most of these superconducting magnets are below the transition iprúd I _L of the magnet in the normal state which corresponds to the critical current I _c krátlkej samples of the superconducting wire. This phenomenon is referred to as degradation and its degree is characterized by a degradation coefficient

K _d = I _p / I _c g 1.

The cause of degradation is the local instability of the superconducting conductor, caused by disturbances of different origin and intensity, which ultimately result in local heating of the superconducting conductor. The most common failure is the movement of winding parts, e.g. threads or parts thereof. Impregnating winding with various materials such as epoxy resins, oil, paraffin is used to remove degradation.

This method of manufacturing a SC winding is technologically demanding, requiring testing of suitable embedding compositions and often fails to produce successful results because it worsens the heat transfer from the winding to the liquid helium and, moreover, the embedding material becomes a source of thermal impulses upon cracking.

The above-mentioned disadvantages are substantially eliminated by the winding of the superconducting magnet according to the invention, which is based on the fact that a thermally and electrically conductive foil, preferably aluminum, is placed between the winding layers.

The main advantage of the invention is simplicity, low materiality and does not require additional equipment and technological operations, as is the case with winding impregnation technology. Aluminum foil makes it easier to keep the exact geometry of the wound layers. In addition, the entire winding and / or winding is possible in case of need caused by a superconducting conductor fault. simply unwind the necessary part and reuse the superconducting conductor. The insertion of metal foils reduces the coefficient of filling of the winding with a superconducting conductor, but this effect is outweighed by significantly reducing degradation. Ultimately, with a given amount of superconducting conductor, it is possible to achieve a higher magnetic field or to save 10 to 20% of the superconducting conductor in producing a magnet with the same magnetic then.

The accompanying drawing shows an example of a superconducting magnet winding with an aluminum foil interposed between the superconducting conductor layers.

The superconducting magnet winding consists of a superconducting conductor 1 wound in cylindrical layers, which are separated by an aluminum foil 2 and an interlayer insulation 3. The superconducting magnet face 4 is provided with grooves S through which the edges of the aluminum foils 2 are cooled.

Example 1

A cylindrical shape of a superconducting magnet of a multi-fiber niobium-titanium (NbTi) superconductor having an outer diameter of 1 mm is wound onto a stainless steel frame. The net inside diameter of the carcass is 60.5 mm, the outer diameter of the winding is 140 millimeters, the winding length is 200 mm. In use, the stabilizing aluminum foil with a thickness of 0.15 mm interposed between the layers of the magnet coil is made superconducting transition current I _p superconducting magnet in the normal state 243 A. This current is substantially equal to the critical current I _{of the} short samples of the superconducting wire, so that the rate of degradation K _d = 1. The superconducting magnet reached a magnetic field at the center of the superconducting magnet at 7.1 t at the transition current I _p . Example 2

A Helmholz twin-coil superconducting magnet having a net internal winding diameter of 186.5 mm, an outer winding diameter of 304 mm and a coil height of 84 mm is wound from a 1 mm outer diameter of a superconducting niobium-titanium wire onto a stainless steel frame with glass-fiber ends.

An aluminum foil of 0.13 mm thickness and an insulating paper foil of 0.02 mm thickness are inserted between each layer in the SC winding. After 14 energies, the superconducting magnet reached the maximum transition current I _p = 204 A. At this current, the magnetic field at the center of the superconducting magnet is 6.32 T and the maximum magnetic field on the winding was 7.53 T. When comparing the critical current I _{c of a} short sample with achieved superconducting magnet current we get degradation coefficient K _d = 0,9. The design current density in the SC coil was 1.7. 10 ⁴ A. cm ^-2 in a magnetic field of 7.53 T.

The invention can find application in the construction of small and medium size superconducting magnets for research and industrial applications.

Claims (1)

Viautle superconducting magnet, characterized in that a thermally and electrically conductive foil, preferably aluminum, is placed between the winding layers.