JP3418862B2 - Radiation shield plate - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation shield plate covering a superconducting coil, and more particularly to a radiation shield plate capable of preventing damage when a quench occurs in the superconducting coil.

[0002]

2. Description of the Related Art As shown in FIG. 5, a superconducting magnet device includes a superconducting coil 51, a vacuum container 52 for accommodating the superconducting coil 51 therein, and for vacuum heat insulation between the superconducting coil 51 and the outside. It has a radiation shield plate 53 for blocking radiant heat from the vacuum container 52 to the superconducting coil 51.

The superconducting coil 51 is cooled to a cryogenic temperature by a refrigerator 54 attached to a vacuum container 52 or a refrigerant such as liquid helium filled in a container (not shown). Then, the superconducting coil 51 is energized to generate a magnetic field after being in the superconducting state.

The vacuum container 52 prevents external heat from being transmitted to the superconducting coil 51, and enhances the cooling efficiency of the superconducting coil 51 by the refrigerator 54 or the refrigerant.

The radiation shield plate 53 prevents radiant heat from the vacuum container 52 at room temperature from being transmitted to the superconducting coil 51. The radiation shield plate 53 is generally maintained at 77 K ° by liquid nitrogen. Or two-stage G
It is connected to the 1st cooling stage of the M refrigerator, 50-60K
Maintained at °. If the temperature of the radiation shield plate 53 rises, the radiant heat transmitted to the superconducting coil 51 increases and the temperature of the superconducting coil 51 rises. As a result, the current that can be passed through the superconducting coil 51 decreases, and the strength of the generated magnetic field decreases. Therefore, it is important not to raise the temperature of the radiation shield plate 53 during operation of the superconducting magnet device. Therefore, the radiation shield plate 5
As the material for No. 3, oxygen-free copper or high-purity aluminum, which has good thermal conductivity, is often used.

[0006]

During operation of the superconducting coil, a phenomenon called quench may occur in which the superconducting state changes from the superconducting state to the normal conducting state and the temperature rises rapidly. When a quench occurs, it is necessary to rapidly reduce the energizing current in order to prevent the superconducting coil from burning. At that time, a large induced current is generated in the member having a high electric conductivity located in the vicinity of the superconducting coil.

In the superconducting magnet device, a radiation shield plate is arranged near the superconducting coil. The material of the radiation shield plate is a good electric conductor such as oxygen-free copper or high-purity aluminum. Therefore, when quenching occurs in the superconducting coil and the applied current is rapidly reduced, a large induced current is generated in the radiation shield plate. Then, due to the interaction between the induced current generated in the radiation shield plate and the magnetic field generated by the superconducting coil, a large electromagnetic force acts on the radiation shield plate. This large electromagnetic force may damage the radiation shield plate.

The electromagnetic force acting on the radiation shield plate is shown in FIG.
This is the direction toward the superconducting coil, as indicated by the arrow. That is, the radiation shield plate flat plate portion 53a that covers the upper surface of the superconducting coil 51 receives a downward force, and the radiation shield plate flat plate portion 53b that covers the lower surface receives an upward force.
The radiation shield plate outer cylinder portion 53c that covers the outer circumference of the superconducting coil 51 receives an inward force, and the radiation shield plate inner cylinder portion 53d that covers the inner circumference receives an outward force.

Of the four parts constituting the radiation shield plate, the outer cylinder portion 53c and the inner cylinder portion 53d are provided with slits to cut the closed circuit through which the induced current flows, so that the induced current generated therein is generated. It can be drastically reduced. Therefore, the outer cylinder portion 53c and the inner cylinder portion 53d can be prevented from generating a large electromagnetic force that causes damage.

On the other hand, regarding the flat plate portions 53a and 53b, even if slits are provided, the outer cylinder portion 53c and the inner cylinder portion 53d.
As described above, the effect of reducing the induced current cannot be obtained. Therefore, a large electromagnetic force is generated on the flat plate portions 53a and 53b, which may damage them. In order to prevent breakage, it is possible to increase the plate thickness of the flat plate portions 53a and 53b to improve the strength thereof, but if the plate thickness is increased, the cross-sectional area of the path through which the induced current flows becomes large and its resistance is increased. There is a side effect that it becomes small and the induced current easily flows, and as a result, the induced current becomes large. That is, increasing the plate thickness of the flat plate portions 53a and 53b increases the electromagnetic force generated there, and is not very useful in preventing damage.

An object of the present invention is to provide a radiation shield plate for a conductive magnet device which is not damaged even if a quench occurs in the superconducting coil.

[0012]

According to the present invention, there is provided a radiation shield plate for covering the superconducting coil in order to shield the radiant heat directed to the superconducting coil, wherein both ends (for example, upper and lower surfaces) of the superconducting coil are provided. The radiation shield plate for covering has a heat transfer plate for blocking the radiant heat and a reinforcing plate having a lower thermal conductivity than the heat transfer plate, and the heat transfer is performed so that the reinforcing plate faces the superconducting coil. A radiation shield plate is obtained, which is characterized in that a plate and the reinforcing plate are superposed on each other.

The heat transfer plate may be divided into a plurality of pieces in the circumferential direction.

The heat transfer plate may be made of copper or aluminum, and the reinforcing plate may be made of stainless steel, titanium, or FRP.

Fixing to a mounting flange formed on a cylindrical radiation shield plate that covers the outer circumference of the superconducting coil is performed by making the radius of the heat transfer plate larger than the radius of the reinforcing plate, and then the outer peripheral edge of the heat transfer plate. Is bent so as to surround the outer peripheral edge of the reinforcing plate, and the outer peripheral edge of the heat transfer plate is sandwiched between the mounting flange and the reinforcing plate. Alternatively, the reinforcing plate is fixed to a surface of the mounting flange that is formed on the cylindrical radiation shield plate that covers the outer circumference of the superconducting coil and that protrudes toward the inner peripheral side, the surface facing the superconducting coil, and the heat transfer plate is The holding flange is used to fix the mounting flange to the surface opposite to the surface facing the superconducting coil.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows the first embodiment of the radiation shield plate of the present invention. As shown in FIG. 1A, the radiation shield plate (flat plate portion) according to the present embodiment has a reinforcing plate 11 and a heat transfer plate 12.

The reinforcing plate 11 can be used at extremely low temperatures,
It is made of a material having high electric resistance and low thermal conductivity, such as stainless steel, titanium, or FRP. The heat transfer plate 12 is made of oxygen-free copper, high-purity aluminum, or the like having high thermal conductivity.

The reinforcing plate 11 and the heat transfer plate 12 are shown in FIG.
It has a disk shape as shown in. Then, these are so that the reinforcing plate 11 faces the superconducting coil (not shown) (to face the inner side of the radiation shield plate outer cylinder portion 13).
And is fixed to a mounting flange 14 protruding toward the inner peripheral side so as to close the lower end (or the upper end) of the outer tube portion 13 of the radiation shield plate.

The thickness of the heat transfer plate 12 may be such that the heat conduction characteristics required for the radiation shield plate can be obtained. That is, the thickness of the heat transfer plate 12 may be the minimum necessary thickness, for example, about 1 mm. On the other hand, the thickness of the reinforcing plate 11 is set to, for example, 6 mm, which is strong enough not to be destroyed even by the electromagnetic force generated in the heat transfer plate 12 when the quench occurs.

Next, a method of attaching the reinforcing plate 11 and the heat transfer plate 12 to the attaching flange 14 will be described with reference to FIG.

Here, the radius of the heat transfer plate 12 is the reinforcing plate 1.
The radius is larger than 1. The peripheral edge of the heat transfer plate 12 is bent so as to wrap around the peripheral edge of the reinforcing plate 11. Then, the periphery of the bent heat transfer plate 12 is
The reinforcing plate 11 is fixed to the mounting flange 14 with the bolts 21 so as to be sandwiched between the reinforcing plate 11 and the mounting flange 14.

Since the peripheral edge of the heat transfer plate 12 is sandwiched between the mounting flange 14 and the reinforcing plate 11 as described above, the heat transfer plate 12 directly contacts the radiation shield plate outer cylinder portion 13 and is excellent. It is possible to realize excellent heat conduction characteristics.

Next, another method for attaching the reinforcing plate 11 and the heat transfer plate 12 to the attaching flange 14 will be described with reference to FIG.

The reinforcing plate 11 is placed inside the radiation shield plate 13 and on the upper surface of the mounting flange. At this time, a step is formed in the peripheral portion of the reinforcing plate 11 so that the lower surface of the reinforcing plate 11 forms the same plane as the lower surface of the mounting flange 14. The heat transfer plate 12 is placed on a plane formed by the mounting flange 14 and the reinforcing plate 11, and the pressing plate 31 is provided.
Fixed by. The pressing plate 31 is attached to the heat transfer plate 12 by bolts 32 that fix the reinforcing plate 11 to the mounting flange 14.
It is fixed to the mounting flange 14 via.

Also in this method, since the heat transfer plate 12 is in direct contact with the radiation shield plate outer cylinder portion 13, good heat conduction characteristics can be realized. Further, in the present method, it is not necessary to bend the peripheral edge portion of the heat transfer plate 12 as in the case of the attachment method shown in FIG. 2, so that the manufacturing is easier than in the method shown in FIG.

Although the reinforcing plate 11 and the heat transfer plate 12 are both disc-shaped in the above-mentioned embodiment, when the inner peripheral side of the superconducting coil is covered by the inner tube portion of the radiation shield plate, they are It is necessary to make the shapes of the reinforcing plate 11 and the heat transfer plate 12 annular, and to fix them to the mounting flange formed on the inner cylindrical portion. In this case, the method shown in FIGS. 2 and 3 can be used as the method of fixing to the mounting flange formed on the inner cylindrical portion.

Further, in the above embodiment, only the radiation shield plate flat plate portion covering the lower surface of the superconducting coil has been described, but the present invention is also applied to the radiation shield plate flat plate portion covering the upper surface of the superconducting coil.

Furthermore, in the present embodiment, the radiation shield plate covering the upper and lower surfaces of the coil has been described, but other uses are possible. Further, the shape thereof is not limited to the disc shape, and may be an elliptical race track shape.

Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, four fan-shaped heat transfer plates 41 are used instead of the disc-shaped heat transfer plate 12 in the first embodiment. Here, an example is shown in which the disk-shaped heat transfer plate is divided into four equal parts in the circumferential direction, but it may be divided into two equal parts to form a semicircular plate shape. Moreover, you may use what was divided into 3 or 5 equal parts, or more. In addition, each heat transfer plate needs to be arranged so as not to overlap with other heat transfer plates.

The mounting method shown in FIGS. 2 and 3 can also be used in this embodiment. Further, when the inner peripheral side of the superconducting coil is covered with the inner tube portion of the radiation shield plate, it is necessary to fix it to the mounting flange formed on the inner tube portion as in the first embodiment. is there.

[0032]

According to the present invention, among the radiation shield plates that cover the superconducting coil, a disk-shaped radiation shield plate that covers both ends of the superconducting coil is used as a heat transfer plate that shields radiant heat, and a heat transfer plate By using a reinforcing plate with a low conductivity and stacking it, it is possible to suppress the generation of electromagnetic force while ensuring strength, so even if a quench occurs in the superconducting coil, It is possible to avoid damage to the shield plate.

[Brief description of drawings]

FIG. 1 is a (a) partial side view and (b) a bottom view showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a method of mounting the reinforcing plate and the heat transfer plate of FIG. 1 on a mounting flange.

FIG. 3 is a view showing another method of mounting the reinforcing plate and the heat transfer plate of FIG. 1 on the mounting flange.

FIG. 4 is a partial side view (a) and a bottom view (b) showing a second embodiment of the present invention.

FIG. 5 is a schematic diagram for explaining a superconducting magnet device.

FIG. 6 is a diagram for explaining an electromagnetic force generated in the radiation shield plate of FIG.

[Explanation of symbols]

11 Reinforcement plate 12 heat transfer plate 13 Radiation shield plate outer cylinder 14 Mounting flange 21 bolts 31 Presser plate 32 volts 41 heat transfer plate 51 Superconducting coil 52 Vacuum container 53 Radiation shield plate 54 refrigerator

─────────────────────────────────────────────────── ─── Continued Front Page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01F 6/00-6/06 ZAA H01L 39/02-39/04 ZAA H01L 39/14-39/16 ZAA H01L 39/20 ZAA H02K 55/00-55/06 ZAA B60L 13/02-13/10 ZAA

Claims (4)

(57) [Claims] 1. A radiation shield plate for covering the superconducting coil to shield the radiant heat directed to the superconducting coil, wherein the heat shield plate covers both ends of the superconducting coil, and a heat transfer plate for shielding the radiant heat. and a thermal conductivity lower reinforcing plate than the heat transfer plate, and wherein the heat transfer plate and the reinforcing plate are superposed such that the reinforcing plate facing said superconducting coil, the heat transfer plate Is larger than the radius of the reinforcing plate,
Fold it so that the outer edge of the heat transfer plate encloses the outer edge of the reinforcing plate.
It is bent so that it sandwiches the outer peripheral edge of the heat transfer plate.
A cylindrical shape in which the reinforcing plate covers the outer circumference of the superconducting coil.
Fixed to the mounting flange formed on the radiation shield plate
Radiation shield plate characterized by being. 2. To block radiant heat directed to the superconducting coil
A radiation shield plate for covering the superconducting coil,
Note on the radiation shield plate that covers both ends of the superconducting coil.
The heat transfer plate for blocking the radiant heat, and heat transfer more than the heat transfer plate.
A reinforcing plate having a low conductivity, and the reinforcing plate is the superconducting coil.
The heat transfer plate and the reinforcing plate are overlapped so as to face the coil.
And the reinforcing plate covers the outer circumference of the superconducting coil.
Mounting flange that is formed on the fire shield plate and projects to the inner peripheral side
When it is fixed to the surface facing the superconducting coil,
In principle, the heat transfer plate is the superconducting coil of the mounting flange.
Fixed to the surface opposite to the surface facing the
Radiation shield plate that is characterized by being. The method according to claim 3, wherein the heat transfer plate, in the circumferential direction, the radiation shield plate according to claim 1 or 2, characterized in that divided into a plurality. Wherein said heat transfer plate, made of copper or aluminum, the reinforcing plate is made of stainless steel, according to claim 1, wherein the titanium or is made of FRP, 2 also
Is the radiation shield plate described in 3 .