JP3149731B2 - Superconducting magnet device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting shield for suppressing a coil electromagnetic force (expansion force) acting on a superconducting magnet such as a field solenoid coil used in a superconducting motor.

[0002]

2. Description of the Related Art Conventionally, various superconducting motors have been proposed, and many of them use a superconducting magnet composed of a solenoid coil. In such a superconducting magnet, a strong magnetic field is generated in the bore. on the other hand,
If there is a relatively large space around the superconducting magnet, the surrounding magnetic field is weaker than in the bore, and an electromagnetic force (expansion force) acts on the superconducting magnet. This electromagnetic force increases according to the amount of current, and becomes very large in a superconducting magnet.

For this reason, in the conventional apparatus, the coil of the superconducting magnet is reinforced by means such as hardening with an epoxy resin or winding a stainless wire, so that the superconducting magnet does not expand due to electromagnetic force.

[0004]

However, when such a reinforcing means is employed, there has been a problem that the weight of the apparatus is increased, heat conduction to the coil cannot be sufficiently secured, and quenching is liable to occur.

On the other hand, the magnetic field generated by the superconducting magnet is strong, and it is necessary to provide a magnetic shield so that ordinary lines of magnetic force do not leak to the surroundings. And, as this magnetic shield, using a superconducting shield,
This is disclosed in JP-A-62-89308.

When the superconducting shield is arranged around the superconducting magnet in this way, since the magnetic field lines cannot enter the superconducting shield at all, the magnetic field around the superconducting magnet becomes strong and a reaction force should be generated there. . In JP-A-62-89308, there is no recognition of this reaction force, and since the superconducting shield is not sufficiently close to the superconducting magnet, a reaction force sufficient to sufficiently suppress the electromagnetic force of the superconducting magnet occurs. Although it is unlikely, some reaction should occur.

Therefore, consider the electromagnetic force in the superconducting magnet by the device described in JP-A-62-89308.

First, consider an axial section of a cylindrical solenoid coil 10 as shown in FIG. 6, and divide this section into four layers in the thickness direction (S1 to S4) × 24 in the vertical direction = 24. 1 to 6 are inside, 19 to 24 are outside, 1, 7,
13 and 19 are upper end sides, and 6, 12, 18, and 24 are lower end sides.

[0009] When a current is applied to the solenoid coil 10, a magnetic field surrounding the solenoid coil 10 is formed. For example, as shown in FIG. 7, a downward magnetic field is formed in the bore, but the area through which the magnetic field lines can pass is limited in the bore, so that the magnetic field lines are denser (stronger magnetic field) than the surroundings. Therefore, an electromagnetic force (expansion force) F acts on the solenoid coil 10.

On the other hand, when the cylindrical superconducting shield 11 is arranged close to the periphery of the solenoid coil 10, the magnetic field lines in the space outside the solenoid coil 10 become dense as shown in FIG. Therefore, the electromagnetic force F ′ acting on the solenoid coil 10 is smaller than when the superconducting shield 11 is not provided.

[0011] When the electromagnetic force was examined, it was found that the electromagnetic force was not uniform in the longitudinal direction.

FIG. 9 shows the magnitude of the electromagnetic force F in the radial direction in each of the portions 1 to 24 when the superconducting shield 11 is not present. From this, the electromagnetic force is
It is large in the middle part of the solenoid coil, and is 0.
It can be seen that there are also 6 or less parts. FIG.
Shows the electromagnetic force F 'when the superconducting shield 11 is provided. In this case as well, it can be seen that there is a large portion at the middle portion and about 0.3 at the lower end portion. 9 and 10 show variations in the electromagnetic force in the vertical direction, where the electromagnetic force in the central portions 3 to 22 is set to 1.

If the electromagnetic force is partially different, a displacement occurs between the upper and lower superconducting windings due to different expansion forces, and quench may occur due to friction at this time.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides a superconducting magnet device which is lightweight and capable of suppressing the adverse effects of electromagnetic force while ensuring sufficient heat conduction. The purpose is to.

[0015]

The present invention relates to a superconducting magnet device in which a cylindrical superconducting magnet is surrounded by a superconducting shield, wherein the superconducting shield has a distance from the superconducting magnet at both ends of the superconducting magnet. The superconducting magnet has a shape that is closer to the intermediate portion, thereby making the electromagnetic force acting on the superconducting magnet uniform.

The superconducting shield is characterized in that its longitudinal section is circular or elliptical.

[0017]

As described above, according to the present invention, the distance between the superconducting shield and the superconducting magnet is different between the end portion and the intermediate portion. Therefore, the superconducting shield makes the force applied to the superconducting magnet toward the center almost equal to the expansion force acting on the superconducting magnet in the opposite direction, making the electromagnetic force acting on the superconducting magnet uniform as a whole. it can.

In particular, by making the vertical section of the superconducting shield circular or elliptical, the electromagnetic force in the cylindrical superconducting magnet can be made uniform.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing the overall configuration of the embodiment, in which a cylindrical superconducting magnet 2 composed of a solenoid coil is arranged inside a substantially spherical (slightly crushed vertically) cryostat 1. The superconducting magnet 2 is wound around a bobbin 3, and is formed by winding one wire rod a predetermined number of times in one direction. The cryostat 1 is filled with a refrigerant 4, and the upper opening of the cryostat 1 is closed by a lid 5. The bobbin 3 is fixed inside the cryostat 1 by mounting members 6, 7, 8. A superconducting shield 9 is provided at a location corresponding to the periphery of the superconducting magnet 2 on the inner surface of the cryostat 1 (excluding the center of the upper surface and the bottom surface of the cryostat 1).

Here, the cryostat 1 and the lid 5
Is for accommodating the refrigerant 4 and the like, and is made of FRP (reinforced plastic), SUS304 (stainless steel) or the like. The superconducting magnet 2 and the superconducting shield 9 are made of a metal superconducting material such as NbTi or an oxide superconducting material such as Bi or Y.
It is wrapped in a stabilizing material such as l (aluminum) and Cu (copper). The superconducting magnet 2 is formed of a wire, and the superconducting shield 9 is formed of a thin plate. The coolant 4 is for maintaining the superconducting material at a temperature for maintaining the superconducting state in a superconducting state, and liquid helium, liquid nitrogen, liquid hydrogen, or the like is appropriately used according to a required temperature. Further, the bobbin 3 and the mounting members 6, 7, 8
Like the cryostat 1, it is made of FRP (reinforced plastic), SUS304 (stainless steel), or the like.

In such a device, when a current is passed through the superconducting magnet 2, a magnetic field corresponding to the current is generated. Basically, a magnetic field similar to that shown in FIG. 6 or 7 is generated. However, in this embodiment, the substantially spherical superconducting shield 9 is disposed so as to surround the superconducting magnet 2. Therefore, the magnetic field generated by the superconducting magnet 2 is regulated by the superconducting shield 9.

In particular, in the superconducting shield 9 of this embodiment,
The upper and lower ends of the superconducting magnet 2 are inclined, and the distance from the superconducting magnet 2 is short.

Therefore, due to the presence of the superconducting shield 9, the lines of magnetic force are bent, and the electromagnetic force in the superconducting magnet 2 becomes different from that when the superconducting shield 9 is cylindrical.

In particular, in the present embodiment, the superconducting shield 9 is inclined, so that the ratio of the radial force to the axial force can be set arbitrarily, and the electromagnetic force in the superconducting magnet 2 is set to an arbitrary value. can do.

FIG. 2 shows the electromagnetic force of each layer in the device of this embodiment. As described above, when the center is set to 1, the electromagnetic force at the upper and lower ends is 0.8 or more, and it is understood that the electromagnetic force can be made uniform.

As described above, in this embodiment, the variation in the electromagnetic force due to the portions in each layer of the superconducting magnet can be greatly reduced. For this reason, a uniform electromagnetic force acts on the coil constituting the superconducting magnet 2, and the friction caused by the relative movement between the superconducting wires constituting the superconducting magnet can be reduced, thereby preventing the occurrence of a quench caused by this. be able to.

FIG. 3 shows the total electromagnetic force applied to the superconducting magnet 2 when the superconducting shield without the superconducting shield, the cylindrical superconducting shield, and the superconducting shield of this embodiment are arranged. As a result, a large outward force is applied when there is no superconducting shield, and an inward force is applied as a whole in the case of a cylindrical shield, which is almost zero in this embodiment.

As described above, according to the present embodiment, it is understood that the electromagnetic force applied to the superconducting magnet 2 can be effectively suppressed, and the reinforcement in the superconducting magnet 2 can be reduced. Therefore, the superconducting magnet can be reduced in size, and
The contact of the refrigerant with the wire of the superconducting magnet 2 is easy, the cooling effect is enhanced, and the possibility of occurrence of quench can be reduced.

FIGS. 4 and 5 show other examples of the configuration of the superconducting shield 9. FIG. As described above, the superconducting shield 9 may be formed into a spherical shape having an opening only at the upper portion or a spherical shape having no opening.

The superconducting magnet according to the present invention can be used as a superconducting motor in which a rotor is arranged in the bore and the rotational force of the rotor is output. In this case, various types of rotors can be adopted, but a disk-shaped rotor whose current direction to the rotor coil can be changed with rotation is suitable.
Then, the configuration of the superconducting magnet forming the stator of such a superconducting motor can be simplified, so that the size and weight can be reduced as a whole, and the possibility of occurrence of quench can be reduced.

[0031]

As described above, according to the present invention,
By making the distance between the superconducting shield and the superconducting magnet different between the end portion and the intermediate portion of the superconducting magnet, the electromagnetic force in the superconducting magnet is made uniform by the superconducting shield. Therefore, the displacement between the wires constituting the superconducting magnet hardly occurs, and the occurrence of quench due to friction can be prevented.

Further, since a force directed toward the center is applied to the superconducting magnet by the superconducting shield, the electromagnetic force (expansion force) acting on the superconducting magnet can be suppressed, and reinforcement of the superconducting magnet can be simplified. Further, since the reinforcement is simple, the superconducting wire is easily cooled, and quench hardly occurs.

Further, by making the vertical section of the superconducting shield circular or elliptical, the electromagnetic force in the cylindrical superconducting magnet can be made uniform.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment.

FIG. 2 is a diagram showing a distribution of electromagnetic force in an example.

FIG. 3 is a diagram showing electromagnetic force of an example and a conventional example.

FIG. 4 is a diagram showing another configuration example.

FIG. 5 is a diagram showing still another configuration example.

FIG. 6 is a diagram showing the position of each part of the superconducting magnet.

FIG. 7 is a diagram showing a magnetic field without a superconducting shield.

FIG. 8 is a diagram showing a magnetic field when a cylindrical superconducting shield is provided.

FIG. 9 is a diagram showing a distribution of electromagnetic force when there is no superconducting shield.

FIG. 10 is a diagram showing a distribution of electric power when a cylindrical superconducting shield is provided.

[Explanation of symbols]

1 cryostat, 2 superconducting magnets, 3 bobbins, 4 refrigerant.

Claims (2)

(57) [Claims] 1. A superconducting magnet device in which a cylindrical superconducting magnet is surrounded by a superconducting shield, wherein the superconducting shield has a shape in which a distance from the superconducting magnet is shorter than an intermediate portion at both ends of the superconducting magnet. A superconducting magnet device characterized in that the electromagnetic force acting on the superconducting magnet is thereby made uniform. 2. The superconducting magnet device according to claim 1, wherein the superconducting shield has a circular or elliptical longitudinal section.