JPH09246037A - Superconducting magnet equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease current density in the inner periphery, and decrease magnetic field, by forming the section of a superconducting coil in a trapezoid wherein the outer peripheral side is longer than the inner peripheral side. SOLUTION: The section of a superconducting coil 1 is formed in a trapezoid wherein the outer peripheral side 5 of the superconducting coil 1 is longer than the inner peripheral side 6 of the coil 1. As to the maximum empirical magnetic field of the innermost periphery, the strength of magnetic field is reduced by about 10%, on account of the trapezoidal form. Characteristics of the superconducting coil 1 are defined by the maximum empirical magnetic field. As a result, when the maximum empirical magnetic field is reduced, the load factor of a superconducting wire is reduced by that amount, and the margin reaching the quenching is increased. Thereby a stable superconducting coil is obtained, and the quenching phenomenon is made hard to occur.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting magnet device having a superconducting coil formed by winding a superconducting wire in an inner container together with a refrigerant.

[0002]

2. Description of the Related Art For example, a superconducting magnet device for a magnetic levitation railway (linear motor car), which is currently under development, is constructed as shown in FIG. That is, the superconducting magnet device includes a superconducting coil 1 formed by winding a superconducting wire.
And a coolant (liquid helium) 2 for cooling the superconducting coil 1 are housed in the inner tank container 3 and supported by the coil support 4 in the inner tank container 3. The inner tank container 3 supports the electromagnetic force generated by the superconducting coil 1, prevents the destruction of the superconducting coil 1 due to deformation, and stores a predetermined amount of liquid helium as cold soot.

Here, paying attention to the cross-sectional shape of the superconducting coil 1, the superconducting coil 1 has a simple rectangular cross-sectional shape because of its ease of manufacture. Looking at the distribution of the magnetic field generated by the superconducting coil 1 itself along this cross section, as shown in FIG. 8, a high magnetic field region appears on the inner peripheral side of the superconducting coil 1. This is a phenomenon that is physically unavoidable with solenoid coils and racetrack coils. Further, in general, when a superconducting wire is exposed to a high magnetic field, the critical current, which is the maximum current that can be passed through the superconducting wire, decreases, and the quenching phenomenon that breaks the superconducting state is likely to occur. Therefore, the maximum performance of the superconducting coil 1 is defined by the capacity of the superconducting wire on the inner peripheral side exposed to the high magnetic field, although the capacity of the wire on the outer peripheral side of the superconducting coil 1 still has a margin. .

Therefore, conventionally, a grading method has been taken to improve the performance of the superconducting coil 1 as a whole by reducing the current density in the inner peripheral portion to reduce the magnetic field or using a wire having a large critical current. It was

On the other hand, for fixing the superconducting coil 1,
As shown in FIG. 7, the inner and outer peripheral surfaces of the superconducting coil 1 having a rectangular cross section are held by the coil supporting tool 4 with a frictional force in a plane.

[0006]

However, if a grading method is adopted in order to reduce the current density in the inner peripheral side portion of the superconducting coil 1, it is necessary to connect another kind of wire in the middle, which complicates the structure. In addition to being connected, the cross-sectional area of the superconducting coil 1 increases, leading to an increase in weight, and there is a drawback that a slight electric resistance is generated in the connecting portion.

From the standpoint of fixing the superconducting coil 1, in the structure in which the superconducting coil 1 having a rectangular cross section is held by the coil support 4 as shown in FIG. 7, the inner and outer peripheral surfaces of the superconducting coil 1 are flat with friction force. Since there is no choice but to support it, it is easy for slight slippage to occur when vibration is applied. When sliding occurs, frictional heat is generated. When the temperature of the superconducting wire rises due to heat generation, the critical current of the superconducting wire sharply decreases, and in the case of the magnetic levitation railway superconducting magnet device, the superconducting coil 1 which is usually liquid helium temperature (4.2K) is Quenching may occur only when the temperature reaches 7 to 8 K partially.

Further, the superconducting coil 1 must be assembled at room temperature and cooled down to an extremely low temperature.
In this case, the surface pressure between the superconducting coil 1 and the coil supporting tool 4 decreases due to thermal contraction, and slippage is likely to occur with a smaller force. Therefore, it is necessary to minimize frictional heat generation in this portion, and it is necessary to reduce friction particularly in the coil fixing portion, resulting in a complicated structure.

As described above, in the conventional superconducting magnet device, a region having a high magnetic field appears on the inner peripheral side of the superconducting coil 1.
Since the performance of the superconducting coil 1 as a whole is defined by the ability of the superconducting wire passing through this portion, the superconducting coil 1
In order to improve the overall performance, it is necessary to use a thick wire having a high critical current on the inner peripheral side of the superconducting coil 1.

Therefore, the structure of the superconducting coil 1 is complicated, the cross-sectional area and the weight are increased, and a slight electric resistance may be generated in the connection portion, which causes the quench.

On the other hand, when the superconducting coil 1 having a rectangular cross section is held by frictional force via the coil support 4, the conventional structure is simply the abutting of the planes with each other. Slippage is likely to occur.
Then, the slipped portion generates heat and the temperature of the superconducting coil rises, which may cause quenching, and the stability of the superconducting magnet device may be significantly impaired.

An object of the present invention is to obtain a superconducting magnet device having stable characteristics in which quenching hardly occurs.

[0013]

According to a first aspect of the present invention, there is provided a superconducting coil formed by winding a superconducting wire, an inner vessel for accommodating the superconducting coil together with a refrigerant, and the superconducting coil fixedly supported in the inner vessel. And a coil supporting member for forming a superconducting coil having a trapezoidal shape in which the outer periphery of the superconducting coil is longer than the inner periphery of the superconducting coil.

According to the first aspect of the present invention, the cross-sectional area of the inner peripheral side of the superconducting coil becomes smaller than the cross-sectional area of the outer peripheral side, and the current density in the inner peripheral side portion is lowered and the magnetic field is lowered. This reduces the maximum empirical magnetic field of the superconducting coil.

According to the second aspect of the present invention, a superconducting coil formed by winding a superconducting wire, an inner vessel for accommodating the superconducting coil together with a refrigerant, and a coil support for fixing and supporting the superconducting coil in the inner vessel. And the cross-sectional shape of the superconducting coil is formed in a triangular shape with the outer periphery of the superconducting coil as the base.

According to the second aspect of the invention, similarly to the first aspect of the invention, the cross-sectional area of the inner peripheral side of the superconducting coil becomes smaller than the cross-sectional area of the outer peripheral side, and the current density in the inner peripheral side portion is lowered and the magnetic field is lowered. . This reduces the maximum empirical magnetic field of the superconducting coil.

According to the third aspect of the present invention, there is provided a superconducting coil formed by winding a superconducting wire, an inner vessel for accommodating the superconducting coil together with a refrigerant, and a coil support for fixing and supporting the superconducting coil in the inner vessel. And the cross-sectional shape of the superconducting coil is formed in a trapezoidal shape in which the inner periphery of the superconducting coil is longer than the outer periphery of the superconducting coil, and the coil support is composed of a plurality of supporting members that sandwich the outer periphery of the superconducting coil. The superconducting coils are arranged discontinuously in the circumferential direction.

In the invention of claim 3, each support member is
The superconducting coils are discontinuously arranged at predetermined intervals in the circumferential direction, and the outer periphery is sandwiched to support the superconducting coils. As a result, the superconducting coil is supported more firmly.

According to a fourth aspect of the present invention, there is provided a superconducting coil formed by winding a superconducting wire, an inner vessel for accommodating the superconducting coil together with a refrigerant, and a coil support for fixing and supporting the superconducting coil in the inner vessel. And forming the cross-sectional shape of the superconducting coil into a triangular shape with the inner periphery of the superconducting coil as the base, and the coil support is a plurality of supporting members that sandwich the triangular apex of the outer periphery of the superconducting coil. The superconducting coil is arranged discontinuously in the circumferential direction.

In the invention of claim 4, as in the invention of claim 3, the respective support members are discontinuously arranged at a predetermined interval in the circumferential direction of the superconducting coil, and the outer periphery is sandwiched to sandwich the superconducting coil. To support. As a result, the superconducting coil is supported more firmly.

[0021]

Embodiments of the present invention will be described below. FIG. 1 is an explanatory diagram of a superconducting coil according to the first embodiment of the present invention. In the first embodiment, the cross-sectional shape of the superconducting coil 1 is formed in a trapezoidal shape in which the outer periphery 5 of the superconducting coil 1 is longer than the inner periphery 6 of the superconducting coil 1. The superconducting coil 1 is formed by fixing a wire material of a superconducting wire by resin impregnation. The wire may be adhesively fixed using a self-bonding wire.

In FIG. 1, the superconducting coil 1 has a trapezoidal shape in which the outer periphery 5 of the cross-sectional shape is long and the inner periphery 6 is short. In the racetrack type superconducting coil 1 having such a cross-sectional shape, the magnetic field distribution in the radial direction from the inner peripheral side of the point showing the maximum magnetic field has the characteristics shown in FIG.

A characteristic curve S1 of FIG. 2 is a characteristic curve of the superconducting coil 1 having a trapezoidal cross section according to the first embodiment, and a characteristic curve S2 of the conventional superconducting coil 1 having a rectangular cross section. It is a characteristic curve.

The superconducting coil 1 used in this analysis is of a conventional type and has a sectional size of 8 as shown in FIG. 3 (a).
A rectangular section coil of 0 mm × 45 mm is used, and as in the first embodiment, as shown in FIG.
A trapezoidal section coil of m × (80 mm + 10 mm) / 2 is used. That is, the magnetomotive force is 700 kA for the same cross-sectional area.

In FIG. 2, the maximum empirical magnetic field on the innermost circumference side is about 4.6 Tesla for the trapezoidal section coil and about 5.1 Tesla for the rectangular section. Therefore, the trapezoidal shape can reduce the magnitude of the magnetic field by about 10%. Since the characteristics of the superconducting coil 1 are defined by the maximum empirical magnetic field of the coil, if the maximum empirical magnetic field is reduced, the load factor of the superconducting wire is reduced by that amount, and the margin until quenching becomes large.

Therefore, the need for grading is reduced, which leads to simplification and weight saving of the superconducting coil 1.
If graded, a superconducting coil with more stable characteristics can be obtained.

Next, a second embodiment of the present invention is shown in FIG. In the second embodiment, the cross-sectional shape of the superconducting coil 1 is formed in a triangular shape having the outer periphery of the superconducting coil 1 as the base. With such a cross-sectional shape, the maximum magnetic field on the inner peripheral side of the superconducting coil 1 can be reduced as in the first embodiment.

Next, a third embodiment of the present invention will be described. FIG. 5 is an explanatory diagram of the third embodiment of the present invention. In the fourth embodiment, the cross-sectional shape of the superconducting coil 1 is formed in a trapezoidal shape in which the inner periphery 6 of the superconducting coil 1 is longer than the outer periphery 5 of the superconducting coil 1, and the coil supporting member 4 is formed in the superconducting coil 1. It is composed of a plurality of support members 7 that sandwich the outer periphery 5 and is many. The plurality of supporting members 7 are arranged discontinuously in the circumferential direction outside the outer periphery 5 of the superconducting coil 1.

In FIG. 5, the superconducting coil 1 according to the third embodiment has a trapezoidal shape in which the outer periphery 5 of the cross-sectional shape is short and the inner periphery 6 is long. When the inner periphery 6 of the cross section is longer than the outer periphery 5 as described above, the maximum empirical magnetic field on the inner periphery side becomes large in the distribution of the magnetic field, which is expected to be more disadvantageous than the rectangular cross section coil.

However, as in the third embodiment, since a plurality of supporting members as the coil support 4 are attached to the outer peripheral side of the superconducting coil 1 to fix the superconducting coil 1, the fixing force of the superconducting coil 1 is increased. In addition, heat generation due to friction between the coil support 4 and the k superconducting coil 1 is suppressed, so that quenching can be prevented and stability is improved. That is, when the superconducting coil 1 is excited, the convex superconducting coil 1 is firmly pressed against the concave supporting member 7 on both the outer peripheral surface and the side surface by the coil hoop force.
The fixing force of the superconducting coil 1 increases.

Generally, the heat shrinkage of the superconducting coil made of resin and conductor is larger than that of the coil support 4 mainly made of metal. Therefore, it is unavoidable that the coil fixing force is reduced to some extent by cooling to a very low temperature. With the configuration as in the third embodiment, the exciting force of the superconducting coil 1 increases the fixing force in both the circumferential direction and the lateral direction of the superconducting coil 1 to suppress the movement of the superconducting coil 1 and to reduce the heat contraction. The decrease in coil fixing force can be compensated.

Therefore, as compared with the conventional structure in which the superconducting coil 1 is supported by a single-plane frictional force as shown in FIG. 7, the superconducting coil 1 and the coil supporting member 4 (support member 7) are slightly smaller than each other. Sliding is less likely to occur, the temperature rise of the wire due to frictional heat generation is suppressed, and the stability of the superconducting coil 1 is increased.

FIG. 6 is an explanatory view of the fourth embodiment of the present invention. In FIG. 6, the superconducting coil 1 has a triangular cross-sectional shape whose inner periphery 6 is the base. With such a cross-sectional shape, as in the third embodiment, the fixing force of the superconducting coil 1 is increased by exciting the superconducting coil 1, and the superconducting coil 1 and the coil support 4 are provided.
It has an effect of suppressing frictional heat generation due to minute slippage with the (support member 7) and increasing stability of the superconducting coil 1.

As described above, in the third embodiment and the fourth embodiment, the inner periphery 6 of the cross section is longer than the outer periphery 5, and the support member 7 is used as the coil support 4 on the outer peripheral side in the circumferential direction. Since the superconducting coil 1 is fixed and fixed at predetermined intervals, the coil hoop force generated by the excitation of the superconducting coil 1 causes the superconducting coil 1 to be more firmly pressed against the supporting member 7 which is the coil supporting member 4. . Therefore, since the fixing force of the superconducting coil 1 is increased, it is possible to compensate for the decrease in the coil fixing force due to thermal contraction. That is,
Compared with the case where the superconducting coil 1 is supported by the frictional force on a single plane, the coil support 4 is less likely to slip,
The stability of the superconducting coil 1 will be increased.

[0035]

As described above, according to the present invention, since a stable superconducting coil can be obtained, it is possible to obtain a superconducting magnet device in which the quench phenomenon does not easily occur.

That is, according to the invention of claim 1 or claim 2, the cross-sectional shape of the superconducting coil is a trapezoidal shape in which the outer periphery is longer than the outer periphery or a triangular shape having the outer periphery as the base. An empirical magnetic field can be reduced, and a stable superconducting magnet device with a reduced load factor of the superconducting wire can be obtained.

Further, in the invention of claim 3 or claim 4, the cross-sectional shape of the superconducting coil is a trapezoidal shape in which the inner periphery is longer than the outer periphery or a triangular shape having the inner periphery as the base, and the coil hoop force during coil excitation is Since the outer peripheral side of the superconducting coil is circumferentially supported by the plurality of supporting members by utilizing it, the fixing force of the superconducting coil can be increased. That is, frictional heat generation between the superconducting coil and the coil support can be suppressed, and a stable superconducting magnet device can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a superconducting coil according to a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing magnetic field characteristics of the superconducting coil according to the first embodiment of the present invention and a conventional superconducting coil.

FIG. 3 is an explanatory diagram of a superconducting coil having the magnetic field characteristics of FIG.

FIG. 4 is an explanatory diagram of a superconducting coil according to a second embodiment of the present invention.

FIG. 5 is an explanatory diagram of a third embodiment of the present invention.

FIG. 6 is an explanatory diagram of a fourth embodiment of the present invention.

FIG. 7 is an explanatory diagram of a conventional superconducting magnet device.

FIG. 8 is a characteristic diagram showing magnetic distribution characteristics of a conventional superconducting magnet device.

[Explanation of symbols]

 1 Superconducting coil 2 Liquid helium 3 Inner tank container 4 Coil support 5 Outer periphery 6 Inner periphery 7 Support member

Claims (4)

[Claims] 1. A superconducting coil formed by winding a superconducting wire, an inner vessel container for accommodating the superconducting coil together with a refrigerant, and a coil support for fixing and supporting the superconducting coil in the inner vessel container. In the superconducting magnet device, a cross-sectional shape of the superconducting coil is formed in a trapezoidal shape in which an outer periphery of the superconducting coil is longer than an inner periphery of the superconducting coil. 2. A superconducting coil formed by winding a superconducting wire, an inner tank container for accommodating the superconducting coil together with a refrigerant, and a coil support for fixing and supporting the superconducting coil in the inner tank container. In the superconducting magnet device, the cross-sectional shape of the superconducting coil is formed in a triangular shape having the outer periphery of the superconducting coil as a base. 3. A superconducting coil formed by winding a superconducting wire, an inner vessel container for accommodating the superconducting coil together with a refrigerant, and a coil support for fixing and supporting the superconducting coil in the inner vessel container. In the superconducting magnet device, the cross-sectional shape of the superconducting coil is formed in a trapezoidal shape in which the inner periphery of the superconducting coil is longer than the outer periphery of the superconducting coil, and the coil support includes a plurality of sandwiching the outer periphery of the superconducting coil. A superconducting magnet device comprising a plurality of supporting members and discontinuously arranged in the circumferential direction of the superconducting coil. 4. A superconducting coil formed by winding a superconducting wire, an inner tank container for accommodating the superconducting coil together with a refrigerant, and a coil support for fixing and supporting the superconducting coil in the inner tank container. In the superconducting magnet device, the cross-sectional shape of the superconducting coil is formed in a triangular shape having the inner periphery of the superconducting coil as a base, and the coil support holds the apex of the triangular shape on the outer periphery of the superconducting coil. A superconducting magnet device comprising a plurality of supporting members and discontinuously arranged in the circumferential direction of the superconducting coil.