JPH11144940A - Superconducting magnet device - Google Patents

Abstract

(57) [Problem] To provide a conduction cooling type superconducting magnet device which is simple and has good cooling performance. A superconducting coil (1) has a superconducting winding (3) wound on a cylindrical bobbin (2) having a cylindrical part (2a) and a flange part (2b). The winding frame 2 is made of non-magnetic stainless steel.
The heat generated in the winding 3 is transmitted to the winding frame 2, and is conducted to the refrigerator 4 from a good heat conductor 11 a provided in close contact with the inner peripheral portion of the cylindrical portion 2 a of the winding frame via a heat transfer bar 11 b. Cooled. The heat transfer member 11 is formed by the heat conductor 11a and the heat transfer bar 11b.
The heat transfer member 11 is made of copper having good heat conductivity. Since the winding frame 2 has better heat conduction than that made of an insulator, and the heat transfer member 11 has better heat conduction than the winding frame 2, the efficiency is lower than when the outer peripheral portion of the winding 3 is cooled by heat conduction. Can cool well.

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 for cooling a superconducting coil by heat conduction by connecting a refrigerator to a superconducting coil by a heat transfer member.

[0002]

2. Description of the Related Art FIG. 9 and FIG.
FIG. 9 is a cross-sectional view of a conventional conduction-cooled superconducting magnet device disclosed in Japanese Patent No. 2241, and FIG. 10 is a detailed cross-sectional view of a superconducting coil portion. In these figures, 1
Is a superconducting coil having a winding frame 2 and a winding 3 formed by winding a superconducting wire 3a around the winding frame 2. The winding frame 2 has a cylindrical cylindrical portion 2a and disk-shaped flange portions 2b provided at both axial ends of the cylindrical portion 2a.

As shown in the detailed sectional view of FIG. 10, the winding 3 has a superconducting wire 3a wound around a bobbin 2 via an insulating paper 3b, and the insulating paper is also provided between the layers of the superconducting wire 3a wound in layers. 3b
Is inserted. This is for electrical insulation between the superconducting wire 3a and the bobbin 3 and between each phase of the superconducting wire 3a. Also, the superconducting wire 3a itself is covered and insulated with formal resin or the like. When insulation breakdown occurs, the winding 3 is seriously damaged, so insulation is an important design item.

Reference numeral 4 denotes a refrigerator for cooling the winding 3. 5 is a heat transfer plate for cooling the winding 3,
Is formed in a cylindrical shape around substantially the entire periphery thereof, and is provided in sufficient contact with the winding 3. Reference numeral 6 denotes a heat transfer bar for thermally connecting the refrigerator 4 and the heat transfer plate 5.

Next, the operation will be described. The winding 3 is connected to the refrigerator 4 by heat conduction through the heat transfer plate 5 and the heat transfer bar 6.
Cooled by. Usually, a metal material having a high thermal conductivity such as copper or aluminum is used for the heat transfer plate 5 and the heat transfer bar 6 in order to efficiently cool the windings 3. For example, copper (tough pitch copper (Japanese Industrial Standard (hereinafter referred to as JIS) C11)
00)) has a thermal conductivity of about 500 W / m · K at 4K.
It is.

On the other hand, a material such as stainless steel having high strength is usually used for the winding frame 2. This is a commonly used material including a superconducting magnet device of a type in which the winding 3 is directly cooled by liquid helium. The thermal conductivity of stainless steel is generally low. For example, the thermal conductivity of austenitic stainless steel (JIS SUS304) is about 0.2 W / m · K at 4K and about 1/2500 of copper.

As the superconducting wire 3a, a niobium titanium (hereinafter, referred to as NbTi) superconducting wire is generally used. Nb
The critical temperature of a Ti superconducting wire is low, and is usually used at a temperature of about 5K or less. For this purpose, it is necessary to cool the winding 3 and the refrigerator 4 by connecting them firmly thermally. For this purpose, a method is adopted in which the heat transfer plate 5 is directly installed on the windings 3 as shown in FIG. 9 and the windings 3 are cooled via the heat transfer plates 5.

[0008]

Since the conventional conduction cooling type superconducting magnet device is constructed as described above, it is necessary to install the heat transfer plate 4 on the outer peripheral portion of the winding 2. The mounting structure including the heat transfer bar 5 becomes complicated, for example, the electric insulation between the heating plate 4 and the windings 3 is required. In addition, winding 3
There is a problem that it is difficult to make a good thermal connection because the surface has many irregularities.

An object of the present invention is to solve the above-mentioned problems and to obtain a superconducting magnet device having a simple structure and excellent cooling performance.

[0010]

In order to achieve the above object, in a superconducting magnet device according to the present invention, a winding frame having a metal cylindrical portion and a cylindrical tube wound around the cylindrical portion of the winding frame are provided. A superconducting coil provided with a superconducting winding in a shape, a refrigerator, and a heat transfer member for thermally connecting the bobbin and the refrigerator are provided, and the superconducting winding is heat-transferred by the refrigerator through the bobbin. It is intended to be cooled. With this configuration, the heat generated in the superconducting winding is transmitted to the metal bobbin having good thermal conductivity. Since the heat transmitted to the bobbin is cooled by the refrigerator through heat conduction through the heat transfer member, the superconducting winding can be efficiently cooled.

The bobbin has a metal flange formed integrally with a cylindrical portion opposed to the cylindrical portion at a predetermined interval in the axial direction. By integrally forming the metal cylindrical portion and the flange portion, the cylindrical portion and the flange portion can be thermally integrated, and the coil is wound when the cylindrical portion or the flange portion is cooled by heat conduction. The heat resistance between the heat transfer member and the heat transfer member is reduced, which is advantageous for cooling the bobbin by heat conduction.

Further, the heat transfer member has a metal auxiliary heat transfer portion for the inner peripheral portion provided on the inner peripheral portion of the tubular portion of the winding frame. To thermally connect the refrigerator and the bobbin. The heat transfer resistance between the bobbin and the heat transfer member is reduced by the metal auxiliary heat transfer portion for the inner peripheral portion, and the cooling performance is improved. Also, attachment to the winding frame is easy.

The cylindrical portion of the bobbin is provided with a concave portion on the inner peripheral portion thereof, and the auxiliary heat transfer portion for the inner peripheral portion is mounted on the concave portion. Since the heat transfer member is attached to the recessed portion of the winding frame, the heat transfer member does not protrude into the internal space formed by the cylindrical portion of the winding frame, and the internal space can be effectively used. It is suitable for use in a superconducting magnet device for MRI in which a subject is accommodated in a crystal, or a crystal forming device in which a crystal pulling unit is installed.

The auxiliary heat transfer portion for the inner peripheral portion is provided over substantially the entire inner peripheral portion of the tubular portion of the bobbin, and is electrically connected in the circumferential direction by a slit portion forming a slit in the axial direction. This is a cylindrical auxiliary heat transfer section that does not form a closed circuit. Since the auxiliary heat transfer portion for the inner peripheral portion is provided over substantially the entire periphery of the inner peripheral portion of the cylindrical portion of the bobbin, the thermal resistance is reduced. In addition, the slit prevents a closed circuit in the circumferential direction, and suppresses the generation of Joule heat due to the eddy current.

Further, the heat transfer member has a metal side auxiliary heat transfer portion provided on the axial side surface of the flange portion, and is wound around the refrigerator through the auxiliary heat transfer portion for the side surface. The frame is thermally connected. The metal collar has low thermal resistance,
An auxiliary heat transfer portion for the side portion may be connected to this flange portion, and thermal connection is easy.

Further, the heat transfer member has a heat conducting portion directly thermally connected to at least one of the cylindrical portion and the flange portion. Since the heat conducting portion is directly connected to the tubular portion or the flange portion, the configuration is simplified.

The tubular member of the bobbin is made of non-magnetic stainless steel, and the heat transfer member is made of copper or aluminum. Since copper or aluminum has a small thermal resistance, the bobbin can be efficiently cooled.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 1 and 2 show a superconducting magnet device according to an embodiment of the present invention. FIG. 1 is a perspective view, and FIG. 2 is a perspective view showing a modification of FIG. In FIG. 1, superconducting coil 1 has winding frame 2 and winding 3. The winding frame 2 has a cylindrical tubular portion 2a and a disc-shaped flange 2b. The winding 3 is formed by winding a superconducting wire 3a around a winding frame 2 (see FIG. 10).

Reference numeral 4 denotes a refrigerator for cooling the winding 3. The above is the same as that shown in FIGS. 9 and 10, and the winding frame 2 is made of non-magnetic stainless steel, for example, SUS304 (JIS) for both the cylindrical portion 2a and the flange portion 2b. The flange portions 2b are welded to both ends of the cylindrical portion 2a so as to face each other at a predetermined interval, and are thermally integrated with the cylindrical portion 2a. The same applies to the case where an NbTi superconducting wire is used as the superconducting wire 3a of the winding 3 and is covered and insulated with a formal resin or the like.

Reference numeral 11 denotes a heat transfer member having a heat conductor 11a as an auxiliary heat transfer portion for the inner peripheral portion and a heat transfer bar 11b as a heat transfer portion. The good heat conductor 11a is in the shape of a strip bent in an arc shape as shown in FIG. 1 and is attached to the end of the inner peripheral portion of the cylindrical portion 2a of the bobbin 2 by, for example, brazing. . A heat transfer bar 11b is welded to the good heat conductor 11a. Thereby, heat is transmitted from the cylindrical portion 2a to the refrigerator 4 via the heat conductor 11a and the heat transfer bar 11b. The winding 3 is wound around the winding frame 2 via the same insulating paper as the insulating paper 3a in FIG. Both the heat conductor 11a and the heat transfer bar 11b are made of tough pitch copper.

In addition, actually, a heat shield plate, a vacuum chamber, a current lead and the like are installed in addition to these, but illustration thereof is omitted.

Next, the operation will be described. Copper is usually added to the NbTi superconducting wire used for the winding 3 for stabilization. The surface of the superconducting wire is electrically insulated by enamel such as formal resin. Therefore, the winding 3 manufactured by winding the superconducting wire has a high thermal conductivity in the circumferential direction (θ direction),
The thermal conductivity in the radial and axial directions is low. This is because heat is transmitted in the radial direction via the enamel coating of the superconducting wire and the insulating paper 3b (FIG. 10), and in the axial direction via the enamel coating of the superconducting wire. These radial and axial thermal conductivities are generally lower than SUS304, which is generally used for the bobbin 2.

Generally, the thickness of the cylindrical portion 2 a of the winding frame 2 is smaller than the thickness of the winding 3. For example, in a superconducting magnet device for MRI (nuclear magnetic resonance), the outer diameter of the winding 3 is 1.2
m, the axial length of the bobbin 2 is about 1.4 to 2.0 m, and in a superconducting magnet device for a crystal pulling device, the outer diameter of the winding 3 is 1.5 to 2.0 m, and the length of the bobbin 2 The length is about 2 m. The winding thickness of the winding 3 is about 20 to 50 mm, and the thickness of the cylindrical portion 2 a of the winding frame 2 is about 10 mm. Therefore, the thermal resistance of the winding frame 2 is a value sufficiently smaller than the radial and axial thermal resistances of the winding 3. Therefore, a sufficient cooling effect can be obtained even if the windings 3 are cooled via the winding frame 2.

In order to efficiently connect the good thermal conductor 11a and the winding 3 so as to reduce the thermal resistance efficiently, the good thermal conductor 11a is installed on the inner diameter side of the cylindrical portion 2a of the winding frame 2, and The area may be increased. In FIG. 1, the thermal conductor 11a
Is installed in the axial direction and a part of the circumferential direction of the cylindrical portion 2a of the winding frame 2, but as shown in a modified example of FIG. If the heat transfer member 12 is provided with the good heat conductor 12a so as to extend over, the cooling effect is further enhanced.

Embodiment 2 FIG. 3 is a perspective view showing a superconducting magnet device according to another embodiment of the present invention. FIG. 4 is a modification of the superconducting magnet device of FIG. As shown in FIG. 3, when a concave portion 2 c is provided in a part of the inner peripheral portion of the cylindrical portion 2 a of the winding frame 2, and a heat transfer member 13 in which a good heat conductor 13 a is fitted is provided, a good heat conductor 13 a Can be installed without protruding inside the cylindrical portion 2a. Therefore, the internal space of the cylindrical portion 2a, which is the inner diameter of the superconducting coil 1, for example, MR
The subject can be accommodated in the I superconducting magnet device, or the internal space where the crystal pulling unit is installed in the crystal forming device can be effectively used.

Further, as shown in a modified example of FIG. 4, a concave portion 2d in which a part of the winding frame 2 is cut out is provided over substantially the entire length of the cylindrical portion 2a in the axial direction. Good conductor 1
4a may be provided as the heat transfer member 14.

Embodiment 3 5 to 7 show another embodiment of the present invention. 5 is a perspective view of a superconducting magnet device, FIG. 6 is a perspective view showing a modification of FIG. 5, and FIG.
It is a perspective view which shows another modification of.

In FIG. 5, a heat conductor 15a as a cylindrical auxiliary heat transfer portion of the heat transfer member 15 has a predetermined length in the axial direction over substantially the entire circumferential direction of the cylindrical portion 2a of the winding frame 2. A slit portion 15c is provided in close contact with the cylindrical portion 2a and forms a slit in the axial direction, so that a closed circuit of one turn is not formed electrically in the circumferential direction.

As shown in FIG. 5, since the thermal conductor 15a is provided over substantially the entire circumferential portion of the inner peripheral portion of the cylindrical portion 2a, the cooling effect is further enhanced, and the magnet device having a large thermal load can be cooled. Become. Also, since the slit portion 15c is provided, when raising or lowering the magnetic field, the heat conductor 15a
Circulating current for one turn to prevent heat generation.

Further, as shown in a modification of FIG. 6, the heat transfer member 16 may be provided with the good heat conductor 16a not only in the circumferential direction of the inner peripheral portion of the cylindrical portion 2a but also in almost the entire axial direction. Further, when the superconducting coil 1 is divided as shown in another modified example of FIG. 7, a good thermal conductor 17a for cooling the upper bobbin 2 and a good thermal conductor 17a for cooling the lower bobbin 2 are provided.
It is also possible to configure the heat transfer member 17 so as to be thermally coupled and cooled by using the second heat transfer bar 17b.

Embodiment 4 FIG. FIG. 8 is a perspective view of a superconducting magnet device according to another embodiment of the present invention.
In the figure, the heat transfer member 18 has a good heat conductor 18a as a side portion auxiliary heat transfer portion and a heat transfer bar 11b. The good heat conductor 18a has a fan shape conforming to the shape of the side surface of the flange portion 2b of the winding frame 2, and is pressed against the flange portion 2b. Other configurations are the same as those in FIG.

As described above, when the heat conductor 18a is installed on the flange portion 2b of the winding frame 2, it is not necessary to process the inner diameter side of the winding frame 2, so that the manufacturing of the winding frame 2 is easy, and Since it does not project inside the portion 2a, there is an advantage that the space in the cylindrical portion 2a can be used effectively.

In FIG. 8, the thermal conductor 18a is installed without processing the flange portion 2b of the winding frame 2. However, a fan-shaped concave portion is provided in a part of the flange portion 2b, and the thermal conductor 18a is provided. It may be buried. Further, the thermal conductor 18a may be formed in an annular shape which is in close contact with the entire side surface of the flange portion 2b. At this time, to avoid a one-turn loop,
A slit portion is provided in the same manner as the thermal good conductor 15a. Further, the tubular portion is not limited to a cylindrical one, and may be a tubular one having a rectangular or square cross section.

In FIG. 1, the good heat conductor 11a is provided on the inner diameter side of the bobbin 2, and in FIG. 8, the good heat conductor 18a is provided on the flange portion 2b of the bobbin 2. It is needless to say that when the good heat conductors 11a and 18a are provided on both the inner peripheral portion of the cylindrical portion 2a and the side portion of the flange portion 2b, the cooling effect is further enhanced.

Further, a plurality of heat transfer members and refrigerators shown in FIGS. 1 to 4 may be provided in the circumferential direction of the cylindrical portion 2 a of the bobbin 2. Further, the heat good conductor 18a and the refrigerator shown in FIG. 8 can be similarly provided in plural sets in the circumferential direction. The heat conductor may be omitted, and the heat transfer bar 11b in FIGS. 1 and 8 may be directly attached to the inner peripheral portion of the cylindrical portion 2a or the side surface of the flange portion 2b to be thermally connected. At this time,
If the thermal resistance is large, the thermal resistance is reduced to a predetermined value or less by increasing the cross-sectional area of the heat transfer bar 11b, the thickness of the cylindrical portion 2a of the bobbin, or shortening the length of the heat transfer bar 11b.

When copper or aluminum having a high thermal conductivity at a very low temperature, that is, a low thermal resistance, is used as the material of the heat transfer bar and each of the heat conductors described in the above embodiments, the cooling effect is further enhanced. However, it is not limited to these materials. In addition, the winding frame is preferably made of non-magnetic stainless steel from the viewpoint of price, strength, electric resistance, and the like, but is not limited thereto, and may be made of white copper or another material.

[0037]

Since the present invention is configured as described above, it has the following effects. A superconducting coil provided with a winding frame having a metal cylindrical portion and a cylindrical superconducting winding wound around the cylindrical portion of the winding frame, a refrigerator, and a winding frame and the refrigerator are thermally connected. A heat transfer member to be connected is provided, and the superconducting winding is cooled by heat conduction through a bobbin with a refrigerator, so that heat generated in the superconducting winding is a metal bobbin having good heat conductivity. It is transmitted to. Since the heat transmitted to the bobbin is cooled by the refrigerator by heat conduction through the heat transfer member,
The superconducting winding can be cooled efficiently.

The winding frame has a metal flange formed integrally with the cylindrical portion opposed to the cylindrical portion at a predetermined interval in the axial direction. By integrally forming the cylindrical portion and the flange portion, the cylindrical portion and the flange portion can also be made thermally integral, and when the cylindrical portion or the flange portion is cooled by heat conduction, the winding and the winding are transferred. The heat resistance between the heat member and the heat member is reduced, which is advantageous for cooling the bobbin by heat conduction, and the cooling performance can be improved.

Further, the heat transfer member has a metal auxiliary heat transfer portion for the inner peripheral portion provided on the inner peripheral portion of the cylindrical portion of the winding frame. Since the refrigerator and the bobbin are thermally connected, the metal auxiliary heat transfer portion for the inner peripheral portion reduces the heat transfer resistance between the bobbin and the heat transfer member and improves the cooling performance. I do. Also, attachment to the winding frame is easy.

The cylindrical portion of the bobbin is provided with a concave portion at its inner peripheral portion, and the auxiliary heat transfer portion for the inner peripheral portion is mounted in the concave portion. The heat transfer member is attached to the set portion and does not protrude into the internal space formed by the cylindrical portion of the reel,
The internal space can be used effectively, and is suitable for use in, for example, a superconducting magnet device for MRI in which a subject is accommodated in the internal space, or a crystal forming device in which a crystal pulling unit is installed.

The auxiliary heat transfer portion for the inner peripheral portion is provided over substantially the entire inner peripheral portion of the cylindrical portion of the bobbin, and is electrically connected in the circumferential direction by a slit portion forming a slit in the axial direction. Since it is a cylindrical auxiliary heat transfer portion which is configured not to form a closed circuit, the auxiliary heat transfer portion for the inner peripheral portion is provided over substantially the entire inner peripheral portion of the cylindrical portion of the bobbin. And the thermal resistance is reduced. Further, the closed circuit in the circumferential direction is prevented by the slit portion, the generation of Joule heat due to the eddy current is suppressed, and the cooling load can be reduced.

Further, the heat transfer member has a metal side auxiliary heat transfer portion provided on the axial side surface of the flange portion, and is wound around the refrigerator through the side auxiliary heat transfer portion. Since the frame and the frame are thermally connected, the metal flange has a small thermal resistance, and the heat transfer member may be thermally connected to the flange to facilitate the thermal connection.

Further, since the heat transfer member has a heat conducting portion directly thermally connected to at least one of the tubular portion and the flange portion, the heat conducting portion is formed on the tubular portion or the flange portion. The direct connection makes the configuration simple and inexpensive.

The tubular member of the bobbin is made of non-magnetic stainless steel, and the heat transfer member is made of copper or aluminum. Performance is improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a superconducting magnet device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a modification of the superconducting magnet device of FIG.

FIG. 3 is a perspective view showing a superconducting magnet device according to another embodiment of the present invention.

FIG. 4 is a perspective view showing a modification of the superconducting magnet device of FIG.

FIG. 5 is a perspective view showing a superconducting magnet device according to another embodiment of the present invention.

FIG. 6 is a perspective view showing a modified example of the superconducting magnet device of FIG.

FIG. 7 is a perspective view showing another modified example of the superconducting magnet device of FIG.

FIG. 8 is a perspective view showing a superconducting magnet device according to another embodiment of the present invention.

FIG. 9 is a sectional view showing a conventional superconducting magnet device.

FIG. 10 is a detailed sectional view showing details of a coil of a conventional superconducting magnet device.

[Explanation of symbols]

1 superconducting coil, 2 winding frame, 2a cylindrical part, 2b
Flange, 2c, 2d recess, 3 windings, 4 refrigerator,
11, 12, 13, 14, 15, 16, 17, 18 Heat transfer member, 11a, 12a, 13a, 14a, 15a, 1
6a, 17a, 18a Hot conductor, 11b, 17b Heat transfer bar, 15c Slit.

Claims (8)

[Claims] A superconducting coil provided with a winding frame having a metal cylindrical portion and a cylindrical superconducting winding wound around the cylindrical portion of the winding frame; a refrigerator; A superconducting magnet device, comprising: a heat transfer member thermally connected to a refrigerator; and cooling the superconducting winding by heat conduction by the refrigerator through the winding frame. 2. The winding frame has a metal flange formed integrally with a cylindrical portion opposed to the cylindrical portion at a predetermined interval in an axial direction of the cylindrical portion. The superconducting magnet device according to claim 1. 3. The heat transfer member has a metal inner peripheral auxiliary heat transfer portion provided on the inner peripheral portion of the cylindrical portion of the bobbin, and via the inner peripheral auxiliary heat transfer portion. 3. The refrigerator or the bobbin is thermally connected to the refrigerator.
3. The superconducting magnet device according to 1. 4. The cylindrical portion of the bobbin is provided with a concave portion on the inner peripheral portion thereof, and the auxiliary heat transfer portion for the inner peripheral portion is mounted on the concave portion. The superconducting magnet device according to claim 3. 5. The auxiliary heat transfer portion for the inner peripheral portion is provided over substantially the entire periphery of the inner peripheral portion of the cylindrical portion of the bobbin, and is electrically connected in the circumferential direction by a slit portion forming a slit in the axial direction. The superconducting magnet device according to claim 3, wherein the auxiliary heat transfer portion is a tubular auxiliary heat transfer portion that does not form a closed circuit. 6. The heat transfer member includes a metal side auxiliary heat transfer portion provided on an axial side surface of the flange portion, and the refrigerator and the bobbin via the side side auxiliary heat transfer portion. 3. The superconducting magnet device according to claim 2, wherein the superconducting magnet device is thermally connected. 7. The superconducting magnet device according to claim 2, wherein the heat transfer member has a heat conductive portion directly thermally connected to at least one of the cylindrical portion and the flange portion. . 8. The coil member according to claim 1, wherein the tubular member of the bobbin is made of non-magnetic stainless steel, and the heat transfer member is made of copper or aluminum. The superconducting magnet device according to the paragraph.