JPH0955313A - Production of superconducting coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a method for producing a highly reliable superconducting coil having rigid structure inexpensively in which the number of times of quench training is decreased while shortening the cooling time and the quantity of liquid helium to be used is reduced. SOLUTION: A wire 1 is wound around a coil bobbin 2 and applied with a coil case 3 and then quench training is repeated under superconducting state thus arranging the wires 1. Subsequently, it is determined that an intended field is established and the wires 1 are impregnated with an epoxy resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to high energy physics research equipment and medical MRI (magnetic resonance imagination).
g) The present invention relates to a method for manufacturing a superconducting coil used in devices and the like.

[0002]

2. Description of the Related Art A magnet using a superconducting coil formed by winding a superconducting wire is used in various fields by taking advantage of its excellent magnetic field generating ability and high homogeneity of the magnetic field. Among them, the magnetic device for high energy physics research and the medical MRI device require a strong magnetic field distribution over a wide range. Therefore, a long solenoid type superconducting coil is often used. In long solenoids, in order to obtain a high current density, a superconducting wire is wound around several thousand to tens of thousands of turns to form a coil, and after winding, the coil is impregnated with epoxy resin to fix the wire. .

However, at the time of excitation, an electromagnetic force due to the interaction between the magnetic field created by the coil and the current flowing through the superconducting wire acts on the wire, which exceeds the adhesive strength with the resin, causing the wire to move, a so-called wire movement. As a result, frictional heat is generated, which causes a quench that causes a transition from the superconducting state to the normal conducting state, resulting in a problem that the designed magnetic field cannot be obtained from the initial excitation.

The quench phenomenon also occurs due to the heat generated by the strain releasing energy when a crack is generated in the impregnated epoxy resin by the wire movement during excitation.

Therefore, in the superconducting magnet,
After winding and impregnating, the process of quench training of intentionally generating a wire movement and quenching was repeated several tens of times, and the wire rod was designed in a uniform state at a position where no further wire movement occurred. It has to use a method of obtaining a magnetic field, requires expensive liquid helium to approach the designed magnetic field after dozens of quench training, and it takes a long time to cool the coil. There was a flaw. Further, the conventional resin impregnation has a drawback that the adhesive force is weak.

[0006]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to reduce the number of quench trainings, shorten the cooling time and the injection time of liquid helium, and reduce the usage amount of liquid helium. The object of the present invention is to provide a method for manufacturing a superconducting coil which is strong and has high reliability.

[0007]

According to the present invention, after the winding, a quenching is performed by covering the outside with a cylindrical coil case that can sufficiently withstand the electromagnetic force in the radial direction of the coil, performing cryogenic cooling, and performing excitation. Is carried out several times, the wire movement is caused to occur, the wire is gathered at the center of the solenoid, and after confirming that the designed magnetic field is obtained, the superconducting coil is manufactured by a method of impregnating with an epoxy resin.

That is, the present invention is a method of manufacturing a superconducting coil in which a coil bobbin is wound with a superconducting wire, impregnated with resin, and quench training is performed. In the superconducting coil manufacturing method, after the winding, excitation is performed in a superconducting state, and quench training is repeated. A method for manufacturing a superconducting coil, which comprises arranging the superconducting wires and performing impregnation with a resin after confirming that a target magnetic field has been obtained.

Further, the present invention is the method for manufacturing a superconducting coil, wherein a prepreg sheet is wound between the layers of the superconducting wire during winding.

The winding of the superconducting coil is carried out by applying tension to the superconducting wire and pressing the wire in the winding start direction of each layer. Therefore, as shown in FIG. 1, each layer of the coil has a structure in which the pressing direction is different for each layer.

In the present invention, in order to eliminate the unevenness and non-uniformity of each layer, after winding, the coil is covered with a cylindrical coil case to perform cryogenic cooling for excitation.

Since the coil is not impregnated, a wire movement is likely to occur due to electromagnetic force, and quenching is easily caused. After quenching training, the wire rod is generated by the axial compression component of the electromagnetic force generated at the same time.
As shown in FIG. 2, the solenoids gather toward the center of the solenoid, the space between the wire rods gradually disappears, and the wire movement does not occur.

After that, by impregnating with an epoxy resin, the superconducting wire is bonded and fixed in a state where it is gathered at the center of the solenoid. Therefore, since the wire movement is less likely to occur during excitation, the quench phenomenon is less likely to occur. In addition, by providing an epoxy prepreg sheet between the layers, they are integrated after being impregnated with the epoxy resin, so that the adhesive force is increased and a strong structure is obtained.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the superconducting coil according to the present invention will be described below.

(Embodiment 1) The superconducting coil manufactured in this embodiment is of a solenoid type and its target characteristic is a current value of 180 A.
The magnetic field strength was designed to be 7T. For the superconducting wire as the winding, Cu matrix type NbTi ultrafine multi-core rectangular wire 0.7
× 1.4 mm (R is 0.3 mm) was used.

As shown in FIG. 1, the SU having an outer diameter of 140 mm
A Kapton sheet (thickness: 0.13 mm) was wound as an insulating sheet on a coil bobbin 2 made of S316L, and the superconducting wire 1 was wound 30,000 times over the inner diameter of 140 mm, the outer diameter of 210 mm, and the length of 840 mm to form a solenoid coil. I made it. At this time, a tension of 10 kgf was applied to the wire rod 1, and the wire rod 1 was wound in 50 layers while pressing the wire rod 1 in the winding start direction of the layer.

Next, the coil case 3 made of SUS316L was covered on the outside. After that, when cryogenic cooling was performed with liquid helium and excitation was performed, the first quench occurred at a current value of 60A. Further, when the quench was repeated about four times, as shown in FIG. 3, it became possible to energize up to the design value of 180A.

Next, as shown in FIG. 2, the solenoid coil is naturally heated, impregnated with the epoxy resin 4, cured, and cooled again at an extremely low temperature to be excited and designed without quenching. A current of up to 180 A could be applied and a 7.0 T magnetic field was generated. Also, the amount of liquid helium used in 10 quenches was 1900 liters.

(Example 2) A solenoid coil was manufactured in the same procedure as in Example 1, using a wire rod, a coil bobbin, and a coil case having the same shape and dimensions as in Example 1. At this time, an epoxy prepreg glass sheet (thickness 0.13 mm) was wound between the layers of the coil. Further, when excitation was performed in the same manner as in Example 1, as shown in FIG. 3, the first quench occurred at a current value of 81 A, and after that, three times of excitation enabled energization up to the design value of 180 A. After that, when epoxy resin impregnation is performed and excitation is performed again, 1
Excitation at 95 A or higher is possible.

Comparative Example Using a wire rod, a coil bobbin, and a coil case having the same shape and dimensions as those of Example 1, a solenoid was wound immediately after winding the solenoid wire by a conventional manufacturing method, and then impregnated with an epoxy resin and cured. Then, when excitation was performed in the same manner as in Example 1, the first quench occurred at a current value of 90A.
Furthermore, as shown in FIG. 3, after conducting quench training 16 times, it became possible to energize up to the design value 180A. The amount of liquid helium used in 20 quenches was 3
It was 500 liters, which was 1.8 times more than that of the superconducting coil of Example 1. It should be noted that the adhesive strength is from Example 2 to Example 2
Has been greatly improved.

[0021]

As described above, according to the present invention,
It is possible to reduce the number of dozens of quench trainings required in the conventional superconducting coil,
Therefore, the amount of expensive liquid helium used can be reduced, and the time required for injecting liquid helium and the cooling time for the superconducting coil can be shortened, which is economically superior and inexpensive. It has become possible to provide a method for manufacturing a superconducting coil. Further, according to the present invention, it is possible to provide a method of manufacturing a superconducting coil which can increase the adhesive force, has a strong structure, and has high reliability.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a superconducting coil in which a wire material after winding is uneven.

FIG. 2 is a cross-sectional view of the superconducting coil in which quenching is performed after winding and the wire is uniform.

FIG. 3 is a characteristic diagram showing the relationship between the quenching frequency and the quenching current of the superconducting coil according to the present invention and the conventional manufacturing method.

[Explanation of symbols]

 1 (Superconducting) Wire 2 Coil Bobbin 3 Coil Case 4 Epoxy Resin A Example 1 B Example 2 C Comparative Example

Claims (2)

[Claims] 1. A method for manufacturing a superconducting coil, comprising: winding a superconducting wire around a coil bobbin, impregnating the coil bobbin with a resin, and performing quench training. In the method for manufacturing a superconducting coil, after the winding, excitation is performed in a superconducting state, quench training is repeated, A method for producing a superconducting coil, which comprises aligning and confirming that a target magnetic field has been obtained, and then impregnating with a resin. 2. The method for manufacturing a superconducting coil according to claim 1, wherein a prepreg sheet is wound between layers of the superconducting wire during winding.