JPS6215803A - Superconductive coil - Google Patents

Abstract

PURPOSE:To obtain a superconductive coil characterized by no short circuits between conductors, high equivalent regidity and excellent cooling performance, by providing a very thin insulating film around a superconductor. CONSTITUTION:A pancake shaped coil winding 1 is formed by a conductor 2 and lead wires 3. The outer surface of the winding 1 is tightened by a bolt 5 in a band 4. Meanwhile, a very thin insulator 6 having a thickness of about 5-10mum is provided around a very thin superconductor 2 having a thickness of about 100mum and a width of 10mm. In the insulator 6, a resin having a thickness of 2-3mum is applied on a base material having a thickness of 5mum. The resin is hardened on a B stage in a half mode. When the thickness of the insulator is thin and the insulator having a large elastic modulus is used, the equivalent elastic modulus becomes large, and the amount of displacement due to electromagnetic force at the time of current conduction can be made small.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to improvements in superconducting coils, and particularly to highly reliable insulation of superconducting coils suitable for cooling characteristics.

[Background of the invention]

The insulation between the coil conductors of conventional superconducting coils was
As described in Japanese Patent No. 7-8265, spacers were inserted between the conductors at appropriate intervals to sufficiently withstand bending of the conductors, and also served as cooling channels. However, the four ultra-thin superconducting bodies have low rigidity, and if spacers are inserted at intervals, the conductors will short-circuit. On the other hand, in order to prevent this short circuit, a method has also been adopted in which various types of varnish are applied to the surfaces of the four superconducting bodies to bring the conductors into close contact. However, when it comes to special ultra-thin rectangular superconducting bodies, if a varnish is applied and then heat treated to harden the varnish, there is a risk that the characteristics of the superconducting bodies will no longer be exhibited. Also, extremely thin ones have the disadvantage that varnish cannot be applied between the edges of the conductor.

[Purpose of the invention]

An object of the present invention is to provide a superconducting coil conductor insulation system with high equivalent rigidity and good cooling performance.

[Summary of the invention]

The following points are listed as important technical issues for superconducting coils.

(1) The cooling structure for the 'M conductor should be suitable and the superconducting conductor should be kept below the critical temperature.

(2) Improving the equivalent rigidity of the coil windings and suppressing their movement in response to the electromagnetic force generated by the current flowing through the four superconducting bodies.

In order to improve these two points, ultra-thin insulation is brought into close contact with the superconducting conductor to form a suitable superconducting coil without short circuits between the conductors.

[Embodiments of the invention]

Figure 1 shows the configuration of a pancake-shaped coil.
A coil winding 1 is formed of a conductor 2 and a lead wire 3, and the outer periphery of the winding 1 is tightened with a band 4 and a bolt 5.

On the other hand, FIG. 2 shows the insulation structure between the conductors of the winding.

An ultra-thin insulator 6 with a thickness of about 5 to 10 μm is provided around the 4 ultra-thin superconducting bodies 2 with a thickness of about 100 μm and a width of 10 m. For Absolute II #6, a 2 to 3 μm thick resin was coated on a 5 μm thick base material using a special method, and this was semi-cured to B stage. This insulation is wrapped around the conductor using a special device and heated to harden it.

It is conceivable to apply this type of insulation to only one side of the conductor instead of pasting it on both sides in the thickness direction as shown in Fig. 2, but it is extremely thin and there is a high risk of short circuits occurring between the conductors. In this case, it is possible to provide a thick insulating layer on one side, for example, an insulating layer with the same thickness as the conductor, but the amount of displacement of the insulating layer due to electromagnetic force during electromagnetic conduction will be large, causing the coil to move and potentially damaging the superconducting properties. There is.

Generally, when the elastic modulus of a conductor is 100%, the elastic modulus of an insulating layer is about 10 to 20%, and the deformation rate of an insulating layer is large when subjected to the same electrode force.

Furthermore, in the embodiment of the present invention, the ultra-thin insulation is wrapped around the entire circumference of the conductor, but as shown in FIG. . The adjacent conductor is configured to mate with the uncut surface 8 of the insulating layer, as shown in FIG. Even with this configuration, the same effects as described above can be obtained.

In this way, the structure must take into consideration prevention of short circuits between conductors.

The reason why ultra-thin insulation is necessary will be explained below.

The equivalent stiffness of this coil, that is, the apparent elastic modulus, is
Conductor thickness tlmm, total insulation thickness on both sides t2m, elastic modulus of each material E x * E x kg / il
l'', the equivalent elastic modulus is expressed by the following equation.

E, = (tyo+ti)/ (tt/Et+ta/E2
) As can be seen from this equation, it can be seen that the thinner the insulator is and the greater the elastic modulus of the insulator, the larger the equivalent elastic modulus and the smaller the amount of displacement due to electromagnetic force when energized.

〔Effect of the invention〕

According to the present invention, since the ultra-thin insulation is wrapped around the conductor, there is no short circuit between the conductors, and the thickness of the insulation is thin, so that the heat generated when the conductor changes to normal conductivity for some reason cannot be transmitted to the refrigerant. I can do it. Furthermore, since the equivalent rigidity is large, there is little movement (displacement), and a coil winding with suitable superconducting characteristics can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a conductor showing insulation of four superconducting bodies according to an embodiment of the present invention, Fig. 2 is a combined cross-sectional view of a conductor showing another embodiment of the present invention, and Fig. 3 is a pancake-shaped superconducting coil. FIG. 1... Superconducting coil winding, 2... 4 rectangular superconducting bodies,
6...Ultra-thin insulation.

Claims (2)

[Claims] 1. A pancake-shaped coil in which a superconducting conductor is wound flatwise in multiple layers, characterized in that an extremely thin insulator is wrapped around the superconducting conductor. 2. A superconducting coil according to claim 1, characterized in that an extremely thin insulator comprising a base material and a thermosetting resin and semi-cured is provided around the conductor.