JPH11354320A - Substance floating magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain power which levitates substance, by attaching ferromagnetic material ring to the end part of the hollow part of the superconducting or permanent conducting magnet having the hollow part in the axial direction. SOLUTION: In a substance levitating magnet 1, a ferromagnetic material ring 5 is attached to the upper end part of the hollow part of a solenoid superconducting magnet 4 comprising a winding frame 2 and a winding 3 of a superconducting wire. The superconducting magnet 4 can be the magnet having the hollow part in the axial direction and can be pancake, bitter type or the other superconducting magnet. Furthermore, the case using the permanent conducting magnet can be provided. The ferromagnetic material ring 5 can be the ferromagnetic material such as pure iron and permalloy. Furthermore, the ferromagnetic material is arranged so as to cover the end part of the side, to which the ferromagnetic material ring 5 is attached at the hollow part of the superconducting magnet 4. Furthermore, the ferromagnetic material plate is arranged so as to embed the central part in the axial direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method of applying a magnetic field, such as paramagnetism, diamagnetism, or ferromagnetism, to a material by applying a high gradient and high magnetic field to the material so that the material can withstand gravity. It relates to a magnet for levitating.

[0002]

2. Description of the Related Art The force exerted by a magnetic field on a substance is determined by the magnitude of the product B.dB / dx of the magnetic field B and the magnetic field gradient dB / dx. Therefore, when the magnetic field gradient dB / dx changes with respect to the direction of gravity, it becomes possible to levitate a substance against gravity.

For example, water is known to be a diamagnetic substance. However, as shown in FIG. 5, when a strong magnetic field magnet 11 having a central magnetic field of about 20 T is arranged so that its axis is directed to the direction of gravity, the upper end of the magnet is opened. The water droplets 12 can be floated near the part.
This is due to the fact that in a diamagnetic substance, a force acts in a direction in which the magnetic field gradient becomes weaker. On the other hand, the paramagnetic substance 13 such as oxygen can be lifted upward in a glass tube or the like near the opening at the lower end of the strong magnetic field magnet 11 to float. This is because the paramagnetic substance has a magnetically opposite property to the diamagnetic substance, and is attracted in a direction in which the magnetic field gradient becomes strong.

When a substance is levitated by such a method,
Conventionally, a superconducting magnet of the solenoid type or pancake type is used, and the substance is placed in a container near the end of the hollow part where the B · dB / dx is maximum, and the substance is levitated from the container. Was. FIG. 6 shows the relationship between the magnetic field profile and the levitation force of the substance at this time. In FIG. 6, the horizontal axis z is 20
The distance (z) from the center of the magnet on the center axis of the superconducting magnet of T
= 0.15 m is the upper end of the magnet). The magnetic field strength H (left scale) is as shown by a curve 13, and the force F (left scale) applied to the substance is maximum near the upper end of the superconducting magnet as shown by a curve 14 (Mitsuhiro Motokawa: Parity 12, 12 No. 1997, p. 28).

[0005]

However, when a commercially available superconducting magnet is used for levitation of a substance, there are the following problems. That is, in order to levitate a weak diamagnetic substance such as water, the value of B · dB / dx is required to be about 1400 T ² / m, but in order to obtain this value, the aperture of the superconducting magnet having a central magnetic field of about 20 T is required. Part will be used. However, this 20T class superconducting magnet has an initial cost of several hundred million yen and a running cost of several million yen per test. For this reason, it was difficult to meet the need for material levitation.

Of course, if a superconducting magnet having a central magnetic field of about 10 T is used, the cost is reduced to 1/5 of a 20 T class superconducting magnet.
Only about 1/10 is required, but the obtained B · dB / dx value is 400T ² /
m, and it is extremely difficult to obtain a force for lifting a substance against gravity.

An object of the present invention is to provide a low-cost material levitation magnet in view of such problems.

[0008]

According to the present invention, there is provided a magnet for material levitation, wherein a ferromagnetic ring is attached to an end of the hollow portion of a superconducting or normal conducting magnet having a hollow portion in the axial direction. It is a feature. The cross-sectional shape of the ferromagnetic ring is generally square, but may be concave or convex. By attaching such a ferromagnetic ring, the magnetic field gradient at the end of the hollow portion can be enhanced as compared with a superconducting or normal conducting magnet alone, and the levitation force B · dB
/ dx can be increased.

Further, the material levitation magnet according to the present invention may have a structure in which a ferromagnetic disk is disposed so as to cover the end of the superconducting or normal conducting magnet where the ferromagnetic ring is mounted in the hollow portion. With such a configuration, B · dB / dx near the ferromagnetic ring can be further increased.

The material levitation magnet according to the present invention may have a structure in which a ferromagnetic disk is arranged so as to fill a central portion in the axial direction of a hollow portion of the superconducting or normal conducting magnet. Even in such a configuration, B · dB / dx near the ferromagnetic ring can be further increased.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an embodiment of the present invention. This magnet 1 for material levitation has a ferromagnetic ring 5 attached to the upper end of a hollow portion of a solenoid type superconducting magnet 4 comprising a winding frame 2 and a winding 3 of a superconducting wire. The superconducting magnet 4 may have a hollow portion in the axial direction, and may be a pancake type, a bitter type, or another superconducting magnet. A normal conducting magnet may be used. The ferromagnetic ring 5 may be a ferromagnetic material such as pure iron or permalloy, and the type thereof is not limited.

FIG. 2 shows the use state of the material levitation magnet 1 of FIG. The material levitation magnet 1 is housed in a cryostat 6, immersed in liquid helium 7, and maintained in a superconducting state. The cryostat 6 includes a liquid helium tank 8 in which the substance levitation magnet 1 is installed, a vacuum heat insulating tank 9, and a liquid nitrogen tank 10.

The specifications of the superconducting magnet 4 used in the experiment are as follows. Hollow part inner diameter: 100 mm Winding inner diameter: 124 mm Winding outer diameter: 237 mm Winding width: 250 mm Wire dimension: 0.95 mm x 1.35 mm Number of turns: 12000 turns The ferromagnetic ring 5 is made of iron (JIS name SS41). ), With a cross section of 30
It is a rectangle measuring 35 mm x 35 mm. The ferromagnetic ring 5 is the winding frame 2
As shown in FIG.

The material levitation magnet 1 is housed in a cryostat 6 as shown in FIG.
B around the ferromagnetic ring 5 when 12T is generated
The maximum value of · dB / dx was about 1400T ² / m. On the other hand, in the case of the superconducting magnet 4 alone without the ferromagnetic ring 5, the maximum value of B · dB / dx near the end of the hollow portion is about 45%.
0 T ² / m. Therefore, it was confirmed that the attachment of the ferromagnetic ring 5 greatly enhanced B · dB / dx near the end of the hollow portion. Therefore, as shown in FIG. 2, when a water droplet is dropped from the upper portion of the hollow portion of the cryostat 6 containing the material levitating magnet 1 with a glass capillary, the water droplet is stopped near the upper end opening P of the material levitating magnet 1 ( Levitated).

FIG. 3 shows another embodiment of the present invention. In the material levitation magnet 1, a ferromagnetic disk 14 is disposed so as to cover the end of the hollow portion of the superconducting magnet 4 to which the ferromagnetic ring 5 is attached. The other configuration is the same as that of the embodiment of FIG. 1, and the same parts are denoted by the same reference numerals. When the ferromagnetic disk 14 is disposed as described above, B · dB / dx near the ferromagnetic ring 5 can be further increased.

FIG. 4 shows another embodiment of the present invention. The material levitation magnet 1 has a superconducting magnet 4 in which a ferromagnetic disk 14 is arranged so as to fill a central portion in the axial direction of a hollow portion of the superconducting magnet 4. The other configuration is the same as that of the embodiment of FIG. 1, and the same parts are denoted by the same reference numerals. Even when the ferromagnetic disk 14 is arranged as described above, B · dB / dx near the ferromagnetic ring 5 can be further increased.

[0017]

As described above, according to the present invention, by attaching a ferromagnetic ring to a commercially available inexpensive superconducting magnet or normal conducting magnet, the B.dB required for material levitation can be obtained.
You can get / dx. Therefore, an excellent effect that the cost of the material levitation magnet can be significantly reduced and the equipment can be downsized can be obtained.

[Brief description of the drawings]

FIG. 1 is a half-split perspective view showing one embodiment of a substance levitating magnet according to the present invention.

FIG. 2 is a cross-sectional view showing a state of use of the substance levitation magnet of FIG. 1;

FIG. 3 is a half-split perspective view showing another embodiment of the substance levitation magnet according to the present invention.

FIG. 4 is a half-split perspective view showing still another embodiment of the substance levitation magnet according to the present invention.

FIG. 5 is an explanatory view showing a conventional material levitating magnet and a floating state of a substance.

FIG. 6 is a graph showing a profile of a magnetic field required for material levitation.

[Explanation of symbols]

 1: magnet for material levitation 2: winding frame 3: winding 4: superconducting magnet 5: ferromagnetic ring 6: cryostat 14: ferromagnetic disk

Claims (3)

[Claims] 1. A magnet for material levitation, wherein a ferromagnetic ring is attached to an end of said hollow portion of a superconducting or normal conducting magnet having a hollow portion in an axial direction. 2. The magnet according to claim 1, wherein a ferromagnetic disk is arranged so as to cover an end of the superconducting or normal conducting magnet to which the ferromagnetic ring is attached. . 3. The material levitation magnet according to claim 1, wherein a ferromagnetic disk is arranged so as to fill a central portion in the axial direction of a hollow portion of the superconducting or normal conducting magnet.