JPH06325932A - Superconducting coil - Google Patents

Abstract

PURPOSE:To make the cracking and releasing in an impregnating resin hardly occur by a method wherein the electromagnetic stress imposed on the impregnating resin between coil conductors is to be lightened. CONSTITUTION:Within the superconducting coil 1 having no bobbin at all closely wound up with a superconducting wire 2 to be impregnated with an epoxy resin 5, a part of layered coil having no connecting part at all a little to the coil inner diameter side is wound up in the inverse direction to the other layered coil. Otherwise, a superconducting wire is wound up in the same direction to be connected so that a part of the layered coil may be fed with a current in the inverse direction. Besides, a dummy coil and a cylinder are provided inside the coil 1. Furthermore, an aluminum and a copper cylinder having excellent thermal conductivity are provided in outer peripheral side of the superconducting coil 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a quench preventive device for a tightly wound superconducting coil impregnated with an epoxy resin.

[0002]

2. Description of the Related Art A superconducting coil in which a superconducting wire is tightly wound around an outer periphery of a bobbin and impregnated with an epoxy resin is cooled by liquid helium and energized. Between the bobbin and the coil inner peripheral surface, and between the coil conductors, the thermal contraction stress generated due to the large difference in the thermal contraction rate between the Cracks and peeling may occur in the impregnated resin. When cracks and peeling occur, heat is generated by releasing strain energy, so the superconducting coil is quenched (normal conduction transition).
May occur. Therefore, JP-A-60-177602, JP-A-63-219106, JP-A-63-244708 and JP-A-4-1-1
No. 02304 discloses a bobbinless superconducting coil which prevents the occurrence of cracks and peeling of the impregnated resin on the inner peripheral surface of the coil to prevent quenching. However, in the conventional technology, although cracks and peeling of the impregnated resin on the inner peripheral surface of the coil can be prevented, sufficient measures have not been taken against the electromagnetic stress generated inside the coil, and the coil conductors are not Since the concentration of electromagnetic stress applied is large, cracks and peeling may occur in the impregnated resin, causing quenching of the superconducting coil.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a superconducting coil in which cracking and peeling of the impregnated resin are less likely to occur and quenching is less likely to occur.

[0004]

In order to solve the above-mentioned problems, the present invention provides a bobbinless superconducting coil in which a part of the layer coil near the inner diameter of the coil having a large magnetic flux density is connected to another layer coil without a connecting portion. Winded in the opposite direction.

As another means, the superconducting wire to be wound is divided and wound in the same direction as a part of the layer coil and the other layer coil, and some of the layer coils and the other layer coils start to be wound and The winding ends are connected to each other so that the current flowing through some of the layer coils is opposite to that of the other layer coils.

Furthermore, the insulating layer on the outer peripheral side of these two means of superconducting coils was made as thin as possible, and a cylinder made of aluminum and copper having good thermal conductivity was shrink-fitted on the outer peripheral side of the insulating layer.

As another means, a superconducting wire is wound in the same direction and a dummy coil or FR is provided between some coil layers.
A cylinder of P was provided and impregnated with epoxy resin to form a superconducting coil.

[0008]

With the above arrangement, the current flowing in the superconducting coil is in the opposite direction in some layer coils and the other layer coils, so the electromagnetic force generated is also in the opposite direction, and electromagnetic waves are generated in the vicinity of some layer coils. The forces cancel each other out. For this reason, the magnitude of the electromagnetic force applied between the coil conductors is reduced, and the impregnated resin is unlikely to crack and peel from the conductor. Further, since some of the layer coils are reinforced by the impregnation with the epoxy resin, they have an effect of supporting an electromagnetic force outward in the coil radius, and have the same effect as that of providing a cylinder between the layers of the superconducting coil.

Further, since the insulating layer on the outer peripheral side of the superconducting coil is made as thin as possible and a cylinder made of a material having a good thermal conductivity is shrink-fitted on the outer peripheral side, the cooling property and the support of electromagnetic force are improved. .

Further, in a superconducting coil in which a dummy coil or a cylinder of FRP is provided between a part of layers of the superconducting coil, the dummy coil and the cylinder of FRP support the electromagnetic force outward of the coil outer diameter, and the dummy coil and FRP. Since the cylinder does not contribute to the generation of electromagnetic force, it has the effect of relaxing the concentration of electromagnetic force inside the superconducting coil.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIGS.

FIG. 1 shows a longitudinal section of a solenoid-shaped superconducting coil which is an embodiment of the present invention. The bobbinless superconducting coil 1 is manufactured by winding a winding frame that has been subjected to a mold releasing treatment, impregnating with an epoxy resin, and curing the winding frame to remove the winding frame. In FIG. 1, a bobbinless superconducting coil 1 uses an NbTi superconducting wire 2 as a wire material, and a layer coil 3 on the inner circumference side of the coil.
a is wound in ten layers in the same direction, and then a folded portion 4a is provided without cutting the wire material, and some layer coils 3b are provided in the opposite direction.
Is wound around four layers, and then the folded-back portion 4b is provided so that the layer coil 3c on the outer peripheral side of the coil is wound in a direction opposite to a part of the layer coil 3b.
The layers were wound, and the epoxy resin 5 was impregnated and cured. The insulating layer 6 on the outer peripheral side of the bobbinless superconducting coil 1 is shaved as thin as possible to improve cooling performance, and the outer peripheral side of the insulating layer 6 is S
The US band 7 was hung to support the electromagnetic force generated outward in the coil radius. Coil support fittings 9a and 9b provided with recesses 8 having the outer diameter of the coil were attached to the top and bottom of the coil and bolted. When the superconducting coil configured as described above is cooled by liquid helium and excited, the current flowing through the superconducting coil becomes as shown in FIG.
The current direction is opposite to the layer coil 3a on the inner side of the coil and the layer coil 3c on the outer side of the coil, and the magnetic flux is also generated in the opposite direction. Therefore, as shown in FIG. It becomes smaller by canceling out some of the electromagnetic force.

Incidentally, a case of a conventional superconducting coil is shown in FIGS. 4 and 5. The currents flowing in the superconducting coils are in the same direction, and the magnetic fluxes do not cancel each other, so that the electromagnetic force is large and the magnitude of the electromagnetic force on the inner peripheral side of the coil is larger than that of the coil of the present invention (FIG. 3). Therefore, in the superconducting coil of the present invention, the compressive stress and the tensile stress applied to the epoxy resin impregnated between the conductors are smaller than those of the conventional superconducting coil, and the impregnated resin is less likely to crack and peel from the coil conductor.

FIG. 6 compares the effect of the present invention with a conventional example. The vertical axis represents the coil current density when the conventional example is 1.0, and the horizontal axis represents the conventional example which is 1.0. The magnetic flux density of is taken to show the relationship between the coil current density and the magnetic flux density. As is clear from the figure, the characteristic P of the superconducting coil of this embodiment is much superior to the characteristic Q of the conventional example in the coil current density, and is close to the characteristic R of the wire. That is, in the conventional superconducting coil, the current density is quenched at 1 per unit (P · U), whereas in the superconducting coil of this embodiment, the coil current density is 1.
It turns out that up to 2 parts can be excited.

A second embodiment of the present invention will be described with reference to FIG. FIG. 7 shows a vertical cross section of a solenoid-shaped superconducting coil in which supporting metal fittings and the like are omitted. In this example, the superconducting wire was divided into three parts, wound in the same direction, and impregnated with epoxy resin. In this superconducting coil, the layer coil 3 on the inner circumference side of the coil
a and the winding ends of some of the layer coils 3b near the inner circumference of the coil are connected, and some of the layer coils 3b and the beginnings of winding of the layer coil 3c on the outer circumference of the coil are connected. Among them, the number of turns of the layer coils 3a, 3b, 3c is the same as that of the above-described embodiment of the present invention. When the layer coils 3a, 3b, 3c are thus connected, the direction of the current flowing through the layer coil 3b is
Since the directions are opposite to those of a and 3c, some electromagnetic forces cancel each other out in the vicinity of the layer coil 3b as in the embodiment of the present invention, and the same effect as that of the embodiment of the present invention can be obtained. Further, in the second embodiment of the present invention, since the winding is performed in the same direction, the winding work is facilitated, and since it is possible to always apply tension to the winding, the coil conductors can be wound tightly and the impregnated resin layer It is possible to reduce the thickness and prevent the occurrence of resin cracks due to heat shrinkage.

A third embodiment of the present invention is shown in FIG. Figure 8
Shows a longitudinal section in which a cylinder 10 made of aluminum and copper having good thermal conductivity is shrink-fitted on the outer peripheral side of the superconducting coil shown in FIGS. 1 and 7. Since the electromagnetic force generated in the superconducting coil and outward in the coil radius is supported by the cylinder 10, the coil conductor is hard to move, and the impregnated resin is unlikely to crack or peel. Further, since the insulating layer 6 on the outer peripheral side of the superconducting coil 1 can be thinned and the thermal conductivity of the cylinder 10 is good, there is an effect that the cooling property is improved as compared with the superconducting coils of FIGS. 1 and 7.

The fourth and fifth embodiments of the present invention are shown in FIG. In the other fourth and fifth embodiments of the present invention, the superconducting wire is wound in the same direction, and in the fourth embodiment, the dummy coil 11 is wound between the coil layers near the inner circumference of the coil. In the example, the FRP cylinder 12 was provided to form a superconducting coil, and the fourth and fifth examples were impregnated with epoxy resin. In both the fourth and fifth embodiments, since the dummy coil 11 and the FRP cylinder 12 that do not contribute to the generation of the electromagnetic force are inside the coil, the concentration of the electromagnetic force is relieved, and the dummy coil 11 and the FRP cylinder 12 are Since the coil conductor has a function of supporting an electromagnetic force outward from the coil radius, the coil conductor is hard to move, and cracking and peeling of the impregnating resin are hard to occur.

[0018]

According to the present invention, since the electromagnetic stress applied between the coil conductors on the inner diameter side of the coil can be reduced, cracking of the impregnating resin and separation from the conductor can be made less likely to occur.

Therefore, the superconducting coil is unlikely to cause quenching, and a superconducting coil having a high current density and high reliability can be provided.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a solenoid-shaped superconducting coil showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing directions of currents flowing through conductors of the superconducting coil shown in FIG.

FIG. 3 is an explanatory diagram showing the magnitude and direction of an electromagnetic force generated when a current is applied as shown in FIG.

FIG. 4 is an explanatory view showing a direction of a current flowing through a conductor of a conventional superconducting coil.

FIG. 5 is an explanatory diagram showing the magnitude and direction of an electromagnetic force generated when a current is passed as in FIG.

FIG. 6 is an explanatory diagram showing the relationship between the current density and magnetic flux density of a superconducting coil according to an embodiment of the present invention and a conventional superconducting coil.

FIG. 7 is a vertical sectional view of a superconducting coil which is a second embodiment of the present invention.

FIG. 8 is a vertical sectional view of a superconducting coil which is a third embodiment of the present invention.

FIG. 9 is a vertical sectional view of a superconducting coil of another fourth embodiment of the present invention.

[Explanation of Codes] 1 ... Bobbinless superconducting coil, 2 ... Superconducting wire, 3b ... Partial layer coil, 3a, 3c ... Other layer coil, 5 ... Epoxy resin, 6 ... Insulating layer, 10 ... Aluminum and copper cylinder , 11
... dummy coil, 12 ... FRP cylinder.

Claims (4)

[Claims] 1. In a bobbinless superconducting coil formed by winding a superconducting wire in a tight winding a plurality of times and impregnating it with an epoxy resin, a part of the layer coil of the superconducting coil is directed in the opposite direction to the other layer coil without a connecting portion. A superconducting coil characterized by being wound around to reduce the concentration of electromagnetic force generated inside the coil. 2. A bobbinless superconducting coil obtained by winding a superconducting wire in a tight winding a plurality of times and impregnating it with an epoxy resin, wherein the superconducting coil is divided into a certain length of the superconducting wire and wound in the same direction. A superconducting coil, in which lead terminals are connected so that the current direction of the layer coil of the part is opposite to that of the other layer coils. 3. A bobbinless superconducting coil obtained by winding a superconducting wire in a tight winding a plurality of times and impregnating it with an epoxy resin. A cylinder made of aluminum and copper having good thermal conductivity on the outer peripheral side of the superconducting coil. A superconducting coil characterized by being provided. 4. A bobbinless superconducting coil obtained by winding a plurality of superconducting wires in a tight winding and impregnating an epoxy resin, wherein a dummy coil and a cylinder are provided between a part of layers of the superconducting coil. coil.