JPH0564872B2 - - Google Patents

Description

[Detailed description of the invention] Industrial applications The present invention relates to a superconducting magnetic shielding device.

BACKGROUND ART In the field of cryogenic technology, which has been in the spotlight in recent years, the development of technology that utilizes strong magnetic fields generated by the use of superconducting magnets is particularly remarkable. Typical examples include superconducting magnets for confining ultra-high temperature plasma in nuclear fusion reactors, and MHD in the energy field.
In the transportation field, we use superconducting magnets for magnetic levitation trains and superconducting electric propulsion ships, and in the medical field, we use superconducting NMR-CT (nuclear magnetic resonance apparatus), which are used in a wide range of powerful products. There are examples of magnetic field applications. Along with the use of such strong magnetic fields, problems under strong magnetic fields are also becoming apparent. That is, as shown in FIG. 11, due to the influence of the strong magnetic field from the superconducting magnet 1, electrical equipment and measuring instruments placed at the position indicated by reference mark A may malfunction.
It may be necessary to reinforce the structure to resist the attraction or repulsion between the magnetic material made of steel, or if steel tools or small objects near the superconducting magnet 1 are removed from the inner wall of the container housing the superconducting magnet 1. Problems have arisen, such as strong suction and damage to the wall surface.

Therefore, in the conventional magnetic shielding device, as shown in FIG.
The superconducting magnet 1 as a magnetic generation source and an object in a strong magnetic field are coated by this method. In such prior art, since the magnetic shielding effect is small, the number of laminated silicon steel plates 3 is large, which inevitably results in a large and heavy structure. It is not suitable for
In addition, the magnetic field lines 2 of the superconducting magnet 1 are connected to the silicon laminated steel plate 3.
However, since the inside of the steel plate is magnetically saturated by a strong magnetic field of about 20,000 Gauss or more, there are drawbacks such as the magnetic shielding effect of the silicon laminated steel plate 3 is significantly reduced. Therefore, in the field of strong magnetic field applications, it is a priority to find devices that can effectively shield strong magnetism.

Problems to be Solved by the Invention The present invention provides a superconducting magnetic shielding device that has a simple configuration and can completely shield strong magnetism.

Means for Solving the Problems The present invention provides magnetic shielding members 12, 12a, 12 made of a superconducting material, in which a large number of meshes are formed that cover the entire periphery of a magnetic generation source 10 and penetrate in the thickness direction.
b, 20, and a large number of honeycomb-shaped through holes 17 that abut and cover the entire outer peripheral surfaces of the magnetic shielding members 12, 12a, 12b, 20 and penetrate in the thickness direction, and are made of non-magnetic material. each through hole 17
includes a support member 18 formed larger than the mesh, and the support member 18 includes magnetic shielding members 12, 12a,
A superconducting magnetic shielding device characterized in that it is formed thicker than 12b and 20.

Further, the present invention covers the entire periphery of the shielded object 11,
A large number of honeycomb-shaped through holes 17 penetrating in the thickness direction
A support member 18 made of a non-magnetic material is formed.
and a magnetic shielding member 1 made of a superconducting material, in which a large number of meshes are formed that contact and cover the entire outer peripheral surface of the support member 18 and penetrate in the thickness direction.
2, 12a, 12b, 20, the through hole 17 is formed larger than the mesh, and the support member 18 includes the magnetic shielding members 12, 12a,
This is a superconducting magnetic shielding device characterized by being formed thicker than 12b and 20.

Effect According to the present invention, in order to prevent the magnetism from the magnetic source 10 from leaking to the outside, the magnetic source 10
Magnetic shielding members 12, 12 made of superconducting material
a, 12b, and 20, and this magnetic shielding member is
Support member 18 in which honeycomb-shaped through holes 17 are formed
Reinforce with.

Further, according to the present invention, in order to prevent an external magnetic field from reaching the shielded body 11, the shielded body 11 is
1 is covered with a support member 18, and the entire outer peripheral surface of the support member 18 is covered with a magnetic shielding member 1 made of a superconducting material.
2, 12a, 12b, and 20.

Embodiment FIG. 1 is a front view showing the basic structure of the present invention, and FIG. 2 is a plan view thereof. The superconducting magnet 10 as a magnetic generation source is used, for example, to confine ultra-high temperature plasma in a nuclear fusion reactor. Under the influence of the strong magnetic field of this superconducting magnet 10, shielded objects 11 such as various electrical devices and measuring instruments
In order to magnetically shield the
2 is used. The mesh-like magnetic shielding member 12 is
For example, superconducting wire mesh 12a or superconducting porous plate 1
2b.

The superconducting wire mesh 12a includes a plurality of superconducting wires 13,
Consists of 14. The superconducting wires 13 and 14 are overlapped in a mesh pattern so as to intersect with each other, and each of these intersection points 14 is fixed by soldering. As the superconducting wires 13 and 14, for example,
Superconducting materials such as Nb-Ti, Nb ₃ Sn, and Nb-Ti
A superconducting material made of quaternary gold of -Ta-Zr is preferably used. Further, the superconducting porous plate 12b is made of the same superconducting material as the superconducting wire mesh 12a, and has a large number of meshes of through holes formed in its thickness direction.

A region of the superconducting magnet 10 in a direction perpendicular to the lines of magnetic force 15 is covered by the mesh-like magnetic shielding member 12 constituted by the superconducting wire mesh 12a or the superconducting porous plate 12b. Therefore, when the magnetic lines of force 15 of the superconducting magnet 10 reach the magnetic shielding member 12, a current is naturally generated in the magnetic shielding member 12 due to the characteristics of the superconducting material, and an electric current is generated outside the magnetic shielding member 12, that is, on the opposite side from the superconducting magnet 10. The magnetic field applied to the placed shielded object 11 becomes zero. In this way, strong magnetism from the superconducting magnet 10 can be shielded by the mesh-like magnetic shielding member 12 made of superconducting material. Therefore, when the shielded object 11 is, for example, various electrical devices or measuring instruments, malfunctions thereof can be prevented.

FIG. 3 is a perspective view showing the basic structure of the present invention. FIG. 3 is similar to the structure of FIG. 2, and corresponding parts are given the same reference numerals. In this configuration, the superconducting magnet 10 is housed within a box-shaped magnetic shielding member 20. This magnetic shielding member 20 includes a superconducting wire mesh 12 similar to the above-described structure.
a or a superconducting porous plate 12b,
Depending on the magnetic strength of the superconducting magnet 10, the superconducting wire mesh 12a or the superconducting perforated plate 12b may have a double structure or a triple structure. By accommodating the superconducting magnet 10 in the box-shaped magnetic shielding section 20 in this manner, a magnetic shielding effect can be obtained over the entire periphery of the superconducting magnet 10.

FIG. 4 is a plan view of the first embodiment of the present invention,
FIG. 5 is an enlarged front view of section V in FIG. 4, and FIG. 6 is a perspective view thereof. FIG. 4 is similar to the structure of FIG. 3, and corresponding parts are given the same reference numerals. In this embodiment, a support member is provided with a large number of honeycomb-shaped through holes 17 that abut the entire outer peripheral surface of the box-shaped magnetic shielding member 20 having the configuration shown in FIG. 3 and penetrate through the entire outer peripheral surface in the thickness direction. 18. The magnetic shielding member 20 is composed of a superconducting wire mesh 12a or a superconducting porous plate 12b, similar to the configurations shown in FIGS. 1 to 3. Further, as the material of the support member 18, for example, FRP
Non-magnetic materials such as reinforced plastic materials such as copper and aluminum alloy materials are used. When the entire periphery of the superconducting magnet 10 is covered by the magnetic shielding member 20, the magnetic shielding member 20 is subjected to an outward force indicated by an arrow F according to Fleming's left-hand rule, that is, an electromagnetic force repelling the superconducting magnet 10. Force acts. For this reason, the magnetic shielding member 20 is attached to the superconducting magnet 1
It will receive a strong repulsive force from 0. Therefore, the support member 1 for reinforcing the magnetic shielding member 20
8 is required. The support member 18 is formed into a box shape capable of covering the magnetic shielding member 20, and has a large number of honeycomb-shaped through holes 17 formed in its thickness direction. Therefore, it has strength in the direction F in which the electromagnetic force of the superconducting magnet 10 acts. With these, even if a repulsive force from the superconducting magnet 10 acts on the magnetic shielding member 20, the magnetic shielding member 20 is reliably prevented from being deformed or damaged by the force. . In this first embodiment, as is clear from FIGS. 5 and 6, each through hole 17 of the support member 18 is formed larger than the mesh of the magnetic shielding member 12a, in other words, the mesh is dense. It is formed small, thereby making it possible to reliably prevent magnetic leakage. Magnetic shielding member 12a
Since a large number of meshes are formed as described above, the amount of superconducting material constituting the magnetic shielding member 12a can be reduced.

Also, as is clear from Figures 4 and 6,
The support member 18 is formed thicker than the magnetic shielding member 12a, so that the support member 18 reliably receives the electromagnetic force acting on the magnetic shielding member 12a, and the magnetic shielding member 12a receives the electromagnetic force. This can reliably prevent deformation. Each through hole 17 of the support member 18 is formed larger than the mesh, so that the weight of the support member 18 can be reduced.

FIG. 7 is a perspective view showing still another configuration on which the present invention is based. The aforementioned magnetic shielding member 12,
20 was configured to cover each of the superconducting magnets 10, but in the configuration shown in FIG.
A superconducting wire mesh 12a similar to the structure shown in FIGS. 1 and 2 is wound around the superconducting wire mesh 12a to form a cylindrical shape, and the ends of the superconducting wire mesh 12a are fixed by soldering or the like. For example, medical
When working in NMR-CT or strong magnetic fields, etc.
When local magnetic shielding or exposure is required, it can be done by partially covering the human body with a superconducting wire mesh 12a shaped to follow the outer circumferential curve of the human body, or by partially exposing the human body. , it becomes possible to obtain a local magnetic shielding effect under a strong magnetic field.

FIG. 8 is a simplified cross-sectional view of a second embodiment of the invention. The configuration in FIG. 8 is similar to the configuration in FIG. 7, and corresponding parts are given the same reference numerals. In this embodiment, the shielded object 11 is covered by a honeycomb-shaped support member 18 shown in FIGS. 4 to 6 and a cylindrical superconducting wire mesh 12a that covers the entire outer peripheral surface of the support member 18. It is. This superconducting wire mesh 12
In a, the repulsive force against the superconducting magnet 10 is indicated by the arrow F.
The superconducting wire mesh 12a acts in the direction shown by , that is, inward in the radial direction of the superconducting wire mesh 12a.
is prevented from deforming radially inward by the support member 18. In this way, the shielded object 11
The cylindrical superconducting wire mesh 12a and the support member 18
In the structure covered by, the superconducting magnet 10 is large,
This can be advantageously carried out in cases where it is not economically viable to magnetically shield the entire surface, or where it is sufficient to magnetically shield only the shielded body 11.

The support member 18 has a cylindrical overall shape,
The supporting member 18 is made of reinforced plastic material such as FRP, non-magnetic material such as copper or aluminum alloy material, and is arranged on the inner peripheral side of the superconducting wire mesh 12a.
This makes it possible to reinforce the superconducting wire mesh 12a and to magnetically shield the superconducting magnet 10. The rest of the configuration is the same as the embodiment shown in FIGS. 4 to 6 described above, so a description thereof will be omitted.

With reference to FIGS. 9 and 10, experimental results for the configurations shown in FIGS. 1 and 2 described above, which are the basis of the present invention, will be explained. First, Nb−Ti−Ta−Zr
A superconducting wire 13 made of a quaternary alloy with a diameter of about 30 μm,
14, with about 61 lines and a diameter of about 0.35mm.
These superconducting wires 13 and 14 are separated vertically and horizontally by approximately 4
A mesh is formed so that the mesh size is approximately 1.5 mm, and then a tension of approximately 1 kg is applied to each wire 13, 14.
A superconducting wire mesh 12a is created by soldering each vertical and horizontal intersection point 14 while preventing the wire mesh 14 from bending. Next, as shown in FIG. 9, the liquid helium storage tank 4 is placed in a state in which the shielded body 11 is placed approximately in the center of the mesh-like superconducting wire mesh 12a made of the above-mentioned superconducting material.
Immerse in liquid helium 41 in 0. Inside the liquid helium storage tank 40, there is a superconducting magnet 1 for generating a strong magnetic field.
0 is provided, and a strong magnetic field in the direction of arrow B is generated. The magnetic shielding characteristics of the shielded object 11 at this time are shown in FIG. The horizontal axis in FIG. 10 represents the strength B of the magnetic field generated by the superconducting magnet 10, and the vertical axis represents the strength _B1 of the magnetic field passing through the superconducting wire mesh 12a. In this magnetic shielding property test, the rising speed of the magnetic field B was 3000 Gauss per second, line l1 shows the magnetic shielding property when the superconducting wire mesh 12a is not used, and line l2 shows the magnetic shielding property when the superconducting wire mesh 12a is used. Each shows magnetic shielding characteristics. As is clear from this experimental result, it is understood that the magnetic shielding effect when the magnetic shielding device of the present invention is implemented is extremely excellent.

Generally, the superconducting phenomenon occurs at an extremely low liquid helium temperature of about -269°C, so the magnetic shielding members 12 and 20 in each embodiment are
It is used by setting it to 0. However, in the future, if the superconducting phenomenon can be obtained near room temperature, the liquid helium storage tank 40 will become unnecessary, and it will be possible to construct the magnetic shielding members 12 and 20 that are even lighter and more portable.

In the embodiment described above, the superconducting wire mesh 12a was fixed in a cylindrical shape by soldering, but the workability may be improved by using automatic spot welding, for example.

The magnetic shielding device according to the present invention is not limited to nuclear fusion reactors, power generators, etc., and can be implemented in a wide range of other technical fields.

Effects As described above, according to the present invention, the magnetic generation source 10
Magnetic shielding member 1 made of superconducting material around the entire periphery of
2, 12a, 12b, and 20, thereby making it possible to reliably prevent magnetic leakage to the outside. 1
2a, 12b, and 20, it is ensured that the shielded object 11 is shielded from external magnetic fields.

In particular, according to the invention, the magnetic shielding members 12, 12
A, 12b, and 20 are formed with a large number of meshes penetrating in the thickness direction, so that only a small amount of superconducting material is required, and the weight can be reduced.

Further, according to the present invention, the magnetic shielding members 12, 12
a, 12b, 20, a large number of honeycomb-shaped through holes 1
Since the magnetic shielding members 12, 12a, 12 are reinforced by the supporting member 18 formed with
b, 20 can be made thinner, which again requires less superconducting material.

Further, according to the present invention, each of the honeycomb-shaped through holes 17 of the support member 18 includes the magnetic shielding members 12, 12a,
12b, 20, in other words, the magnetic shielding members 12, 12a, 1
The meshes of the magnetic shielding members 12, 12a, 12b, 2 are formed small.
Magnetic shielding by 0 can be ensured.

Further, according to the present invention, as described above, each through hole 17 of the support member 18 is formed larger than the mesh, so that the weight of the support member 18 can be reduced. Moreover, this support member 18 is
Since it is formed thicker than the magnetic shielding members 12, 12a, 12b, 20, the magnetic shielding members 12, 1
The magnetic force acting on the magnetic shielding members 2a, 12b, 20 can be supported with great strength, and deformation of the magnetic shielding members 12, 12a, 12b, 20 can therefore be prevented.

Further, the support member 18 is made of a non-magnetic material, so that no magnetic force acts on any part of the support member 18.
It is sufficient to configure the magnetic shielding members 12, 12a, 12b, and 20 so that they can support the force in the thickness direction, which has the advantage of simplifying the configuration and facilitating assembly. Also achieved.

[Brief explanation of the drawing]

FIG. 1 is a front view showing the configuration that is the basis of the present invention, FIG. 2 is a plan view of the configuration shown in FIG. 1, and FIG. 3 is a perspective view showing another configuration that is the basis of the present invention. 4 is a plan view of the first embodiment of the present invention;
The figure is an enlarged plan view of section V in FIG. 4, FIG. 6 is a perspective view of the embodiment shown in FIGS. 4 and 5, FIG. 7 is a perspective view showing the basic structure of the present invention, and FIG. is a sectional view for explaining the second embodiment of the present invention,
FIG. 9 and FIG. 10 are diagrams for explaining an experiment on the basic configuration of the present invention and its results, and FIGS. 11 and 12 are diagrams for explaining the prior art. 10... Superconducting magnet, 12... Shielded object, 1
2, 20... Magnetic shielding member, 12a... Superconducting wire mesh, 12b... Superconducting porous plate, 13, 14... Superconducting wire, 18... Supporting member.

Claims (1)

[Claims] 1. Magnetic shielding members 12, 12a, 12b, 20 made of a superconducting material and formed with a large number of meshes that cover the entire periphery of the magnetic generation source 10 and penetrate in the thickness direction.
A large number of honeycomb-shaped through holes 17 are formed that abut and cover the entire outer peripheral surfaces of the magnetic shielding members 12, 12a, 12b, and 20 and penetrate in the thickness direction, and are made of a non-magnetic material. Each of the through holes 17
includes a support member 18 formed larger than the mesh, and the support member 18 includes magnetic shielding members 12, 12a,
A superconducting magnetic shielding device characterized in that it is formed thicker than 12b and 20. 2. A large number of honeycomb-shaped through holes 17 are formed that cover the entire periphery of the shielded object 11 and penetrate in the thickness direction,
A supporting member 18 made of a non-magnetic material; and a magnetic shielding member 1 made of a superconducting material, in which a large number of meshes penetrating in the thickness direction are formed, contacting and covering the entire outer circumferential surface of the supporting member 18, and made of a superconducting material.
2, 12a, 12b, 20, the through hole 17 is formed larger than the mesh, and the support member 18 includes the magnetic shielding members 12, 12a,
A superconducting magnetic shielding device characterized in that it is formed thicker than 12b and 20.