JPS5814079B2 - Magnetic shielding device - Google Patents

Description

[Detailed description of the invention] TECHNICAL FIELD The present invention relates to a magnetic deflection device.

Conventionally, magnetic shielding devices have been used to shield experimental equipment, measurement equipment, etc. from weak magnetic fields such as the earth's magnetism.

With the recent development of nuclear fusion devices, the magnetic fields used for nuclear fusion have become extremely high.

For this reason, there is a need for a magnetic shielding device to protect experimental equipment that is sensitive to magnetic fields from this strong magnetic field.

In order to perform magnetic blocking effectively, it is sufficient to completely cover the space in which magnetic blocking is performed with magnetic material, but in reality, a cylindrical magnetic barrier is used because the measuring wire passes through it or ionized gas passes through it. The sealing device cannot be closed at both ends.

If both ends are open, the magnetic field will enter from there, so in order to effectively use the magnetic barrier, the axial length of the magnetic barrier must be two to three times the space required. It becomes large and expensive.

Furthermore, there are also drawbacks such as the installation space is limited due to the relationship with peripheral devices, and the required axial length cannot be obtained in many cases.

The present invention has been made in view of the above-mentioned drawbacks, and an object of the present invention is to provide a magnetic barrier device that is small in size and has a high magnetic barrier effect.

The present invention will be explained below with reference to an actual case shown in the drawings.

In FIGS. 1 and 2, 1 is a magnetic jacket inner cylinder made of a magnetic material (hereinafter referred to as the inner cylinder), and 2 is a magnetic jacket outer cylinder made of a magnetic material and arranged at a distance outside the inner cylinder 1. (hereinafter referred to as the outer cylinder), 3 is a lid provided with openings 3a attached to both ends of the outer cylinder 2, and 4 is a support member for attaching the inner cylinder 1 to the outer cylinder.

The outer cylinder 2 and the lid 3 are made of the same magnetic material.

The opening 3a has substantially the same cross-sectional shape as the inner cylinder 1.

Next, the action will be explained.

The experimental results of the magnetic barrier device having the above configuration are as follows.

The dimensions of the model I made are L=21cm, H124cm,
H2-2cm, W1-7cm, W2-25cm.

The inner tube 1 was made of mu-metal with a thickness of 0.1 mm, the outer tube 2 was made of pure iron with a thickness of 2 mm, and the lid 3 was made of the same material as the outer tube 2.

Figure 3 is a characteristic curve diagram of magnetic resistance, where the horizontal axis shows the distance from the magnetic resistance end and the vertical axis shows the magnetic resistance effect.The larger this ratio is, the better the performance is. show.

The magnetic field outside the magnetic field was 3000er.

10 is the magnetic deflection curve of this device, 11 is the lid 3 of this device
This is the conventional magnetic Jahei curve without .

As is clear from FIG. 3, the magnetic barrier according to the present invention has a magnetic barrier effect seven times that of the conventional one, and the influence of magnetic field penetration from the ends is also very small.

This means that the axial length can be shortened.

In addition, the magnetic barrier effect is proportional to the relative magnetic permeability and thickness of the magnetic material used, and in order for the magnetic barrier device of the present invention to have the same effect as the conventional magnetic barrier, the thickness only needs to be 1/7. Therefore, weight reduction can be achieved.

These effects are caused by the actions described below.1 Since the magnetic field is concentrated at the end of the magnetic barrier, if there is no lid 3, the magnetic material will be saturated, the relative magnetic permeability will decrease, and the magnetic barrier effect will decrease. Put it away.

As a result, the amount of external magnetic field penetrating increases, and a similar phenomenon occurs in the portion adjacent to the end.

This phenomenon occurs one after another toward the inside of the magnetic shield, reducing the overall shielding effect.

With the lid 3, saturation does not occur at the end, so the relative permeability of the magnetic material is higher than when there is no lid, so the shielding effect is higher.

Furthermore, since the magnetic field penetrating the magnetic shielding device is proportional to the size of the cross section of the end, the size of the cross section of the end can be reduced by attaching the lid 3, thereby reducing the influence of external magnetic fields.

FIG. 4 shows another embodiment, and parts having the same functions as those in FIG. 1 are designated by the same reference numerals, so a description thereof will be omitted.

Reference numeral 5 denotes a magnetic barrier tube provided between the inner tube 1 and the outer tube 2, which has a triple magnetic barrier structure and further enhances the magnetic barrier effect.

5 and 6 show other embodiments, in which a lid 6 is attached at both ends of the intermediate magnetic shield cylinder 5 shown in FIG. With something that
The influence of external magnetic fields can be further reduced, and the axial length can be made much shorter.

Note that although the above description has been made regarding double magnetic resistance and triple magnetic resistance, it goes without saying that the same applies to multi-layered magnetic resistance.

As described above, in the magnetic barrier device according to the present invention, openings having substantially the same cross section of the inner shell are provided at both ends of the outer shell, which is arranged at a distance on the outside of the inner shell, so as to fix the lid. (1) The magnetic blocking effect is high, the axial length can be shortened, and the device can be made smaller and cheaper.

(2) By using multiple magnetic shields, it is possible to further reduce the size and further enhance the magnetic shielding effect.

(3) Since the lid has an opening, it has excellent effects such as being able to pass measuring wires, etc., and allowing ionized gas, gas, etc. to pass through.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing one embodiment of the magnetic interference device of the present invention, FIG. 2 is a longitudinal sectional view taken along the line A-A in FIG. 1, and FIG. 3 is a magnetic interference characteristic curve diagram. 4 is a longitudinal sectional view showing another embodiment, FIG. 5 is a longitudinal sectional view showing another embodiment, and FIG. 6 is a longitudinal sectional view taken along line B--B in FIG. 1... Inner tube, 2... Outer tube, 3... Lid, 4... Support material, 5... Magnetic shield tube, 6... Lid.

Claims (1)

[Claims] 1 Consists of an inner cylinder, an outer cylinder disposed outside the inner cylinder with a gap, and a lid fixed to both ends of the outer cylinder and provided with an opening having approximately the same cross-sectional shape as the inner cylinder. Magnetic jamming device.