JP2000312036A - Support structure for heavy structure arranged in low- temperature vessel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a support structure for a heavy structure which is applicable even to a large superconducting magnet device, wherein a large deformation takes place due to thermal shrinkage. SOLUTION: In a vacuum vessel 10, load supporters 16a are provided in the circumferential direction at a plurality of points, with intervals at the bottom part of the vacuum vessel for supporting superconducting coils 11a and 11b, as well as a coil cooling heat conductor 13 which is a winding frame. The load supporters and the coil cooling heat conductor 13 are connected with a support member 20. Moreover related to the support member 20, a plurality of plates are stacked over each other, with the top and bottom parts being alternately connected, so that the thermal shrinkage of the superconducting coils 11a and 11b as well as the coil cooling heat-conductor 13 under a low temperature is absorbed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for supporting a heavy structure disposed in a low-temperature container, and more particularly to a structure for supporting a heavy structure including a superconducting coil in a superconducting magnet device of a refrigerator-cooled type. This type of refrigerator-cooled superconducting magnet device is particularly suitable as a magnetic field source for applying a magnetic field to molten silicon in a single crystal growth apparatus for producing a single crystal semiconductor from molten silicon.

[0002]

2. Description of the Related Art In the production of silicon single crystals, there is known a Czochralski method (CZ method) in which polycrystalline silicon is melted and grown into a single crystal seed crystal. In this method, since the molten silicon is melted in the crucible, thermal convection is generated and the quality of the generated single crystal may be degraded.
Therefore, a method of applying a magnetic field to molten silicon and suppressing convection by electromagnetic braking has been known for the purpose of improving the quality of the generated single crystal. This method is called a magnetic field application type Czochralski method (MCZ method).

[0003] As a method of applying a magnetic field, three types of a vertical magnetic field method, a horizontal magnetic field method, and a cusp magnetic field are known, and one example thereof is disclosed in JP-A-8-188493. As a means for applying a magnetic field, a normal conducting magnet and a superconducting magnet are used. However, the normal conducting magnet is heavy in weight because the use of an iron core is indispensable, and requires enormous power and cooling water. On the other hand, a superconducting magnet usually requires liquid helium cooling, so that the device becomes complicated and large. In addition, the handling of liquid helium is complicated and requires the skill of an operator. In addition, liquid helium must be replenished, and liquid helium costs are high.

Meanwhile, a superconducting magnet (helium-free superconducting magnet) device has been provided which uses an oxide superconducting current lead and conducts and cools a superconducting coil only with a small refrigerator. This type of superconducting magnet device is called a refrigerator-cooled superconducting magnet device, is easy to operate, and is considered to be suitable for a silicon single crystal pulling device.

The refrigerator-cooled superconducting magnet device is arranged around a single crystal growing apparatus and houses a vacuum container containing a superconducting coil for generating a magnetic field, and is arranged above the vacuum container to cool the superconducting coil. And a refrigerating machine. The superconducting coil is supported by a coil cooling heat conductor as a winding frame in a vacuum vessel. The refrigerating stage of the refrigerating machine extends in the vacuum vessel to near a connection portion provided on the heat conductor for cooling the coil. A heat shield plate for preventing intrusion of radiant heat is also arranged in the vacuum vessel.

In such a superconducting magnet apparatus, the superconducting coil in the vacuum vessel and the heat shield plate serving as a heat shield are greatly deformed due to the physical properties of each material due to thermal contraction when cooled to a very low temperature. .

[0007] The superconducting coil and the heat shield plate, which are heavy objects in the vacuum vessel, are fixed by a load support fixed to the vacuum vessel side, and a predetermined structural position is maintained. Here, the load supporting member is required to have a structure that follows the position change or releases the deformation with respect to the deformation due to the heat shrinkage described above, and the structure requires various contrivances.

Usually, the load support has a rigidity capable of withstanding a load and a room temperature part (300K) to a cryogenic part (77K to 4.2K).
A material that does not allow heat to easily enter K) is required. In consideration of this, the material of the conventional load support is a stainless steel material having physical properties with a small amount of heat penetration among metals or a GFRP (glass reinforced fiber resin) having a high rigidity with a resin having a small amount of heat penetration. Is generally used as a plate-shaped or column-shaped part.

On the other hand, the materials used for the winding frame of the superconducting coil and the heat shield plate are copper and stainless steel, and the amount of heat shrinkage thereof is 1 m long when cooled from room temperature to 77K or 4.2K. Has a physical property of shrinking about 3 mm.

FIG. 5 shows a small superconducting magnet device in which the amount of heat shrinkage is less than 1 mm for the left portion. In such a superconducting magnet device, since the deformation due to the heat shrinkage is small, the load support is bent so as to cope with the deformation.

In FIG. 5, a superconducting magnet device is provided with a double cylindrical vacuum vessel 50 containing a superconducting coil 51 for generating a magnetic field, and is disposed above the vacuum vessel 50.
Refrigerator for cooling superconducting coil 51 (not shown)
And The superconducting coil 51 includes a cylindrical winding frame 52.
It is wound around. In this example, the superconducting coil 51 and the winding frame 52 are supported by being suspended from above. For this purpose, the upper lid of the vacuum vessel 50 is provided with upper load supports 53 at a plurality of locations at intervals in the circumferential direction. An annular upper support plate 54 is attached to the lower end of the upper load support 53. A lower load support 55 is provided below the upper support plate 54 at a location corresponding to the upper load support 53. An annular lower support plate 56 is attached to the lower end of the lower load support 55.
The winding frame 52 is fixed to the lower support plate 56. In order to prevent radiant heat from entering the vacuum vessel 50,
A heat shield plate 57 is arranged so as to surround the lower load support 55, the lower support plate 56, and the superconducting coil 51.

In this example, the structure does not allow the deformation acting on the upper load support 53 and the lower load support 55 due to the thermal contraction acting on the upper support plate 54 and the lower support plate 56, but the load support itself is deformed. It is a structure that follows.

On the other hand, a load support used in a superconducting magnet device in which the amount of heat shrinkage is 1 mm or more needs to be provided with a structure for relieving the load.

FIG. 6 shows a superconducting magnet device in which the heat shrinkage exceeds 1 mm for the left portion. FIG.
In the superconducting magnet device, a double cylindrical vacuum vessel 60 containing a superconducting coil 61 for generating a magnetic field,
The superconducting coil 61 is disposed above the vacuum
And a refrigerator (not shown) for cooling the water.
The superconducting coil 61 is wound around a cylindrical winding frame 62. Also in this example, the superconducting coil 61 and the winding frame 62 are supported by being suspended from above. For this purpose, the upper lid of the vacuum vessel 60 is provided with a cylindrical upper Heim column support 63. An annular upper support plate 64 is attached to the lower end of the upper Heim column support 63. Below the upper support plate 64, a cylindrical lower Heim column support 65 is provided at a location corresponding to the upper Heim column support 63. An annular lower support plate 66 is attached to the lower end of the lower Heim column support 65. The bobbin 62 is fixed to the lower support plate 66. In the vacuum vessel 50, a heat shield plate 67 is arranged so as to surround the lower Heim column support 65, the lower support plate 66, and the superconducting coil 61 in order to prevent the invasion of radiant heat.

Here, the Heim column support is
As shown in FIG. 7, a plurality of cylinders 63-1, 63-
By forming a multi-cylinder structure with the spacer 63-4 interposed between 2, 63-3, the allowable bending of the load support can be amplified, and the rigidity in the axial direction can be maintained. Further, the multi-cylinder structure is advantageous in reducing heat intrusion.

[0016]

However, the load supporting structure shown in FIG. 5 cannot be applied to a large superconducting magnet device having a heat shrinkage exceeding 1 mm. On the other hand, the load supporting structure of FIG. 6 has problems such as the complexity of manufacturing the Heim column support and the occupying space is large.

It is an object of the present invention to provide a support structure for a heavy structure which can be applied to a large superconducting magnet device which undergoes large deformation due to thermal contraction.

Another object of the present invention is to enable the above-mentioned object to be realized with a simple structure.

[0019]

According to the present invention, there is provided a supporting structure in which a heavy structure is accommodated in a cryogenic container and the heavy structure is supported by a load support at a plurality of positions. By stacking a plurality of plates between the support and a support member having a structure formed by alternately connecting the upper and lower ends thereof, the heat shrinkage of the heavy structure due to low temperature is reduced. It is characterized in that it is absorbed.

When the low-temperature container is a double-cylinder container having an inner cylinder and an outer cylinder, the heavy structure is cylindrical.

In the case where the low-temperature container is a vacuum container containing a superconducting coil and having a refrigerator for cooling the superconducting coil, the heavy structure is used for cooling the superconducting coil and a coil as a winding frame thereof. The support member connects the load-carrying body and the coil-cooling heat conductor, which are heat conductors and are arranged at a plurality of locations on the bottom of the vacuum vessel at intervals in the circumferential direction.

The superconducting coil and the heat conductor for cooling the coil are further housed in a heat shield container constituting a double cylindrical container in the vacuum container, and the load support is provided in the heat shield container. And extends into the heat shield container through an opening provided at the bottom of the heat shield container, and connects the bottom of the heat shield container and the load support with a support having a Heim column structure.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing a support structure according to the present invention, a refrigerator-cooled superconducting magnet device suitable for applying the present invention will be described.

Referring to FIG. 4, this refrigerator-cooled superconducting magnet device is disposed around a single crystal growing device (not shown) and has superconducting coils 11a and 11b for generating a magnetic field.
And a vacuum vessel 10 disposed above the vacuum vessel 10 for cooling the superconducting coils 11a and 11b.
And more than one refrigerators 12. In the refrigerator 12,
A compressor for compressing, supplying and circulating helium gas as a refrigerant is connected. Briefly, the refrigerator 12 shown in the drawings has an electric motor that switches a rotary valve for switching the introduction and discharge of helium gas, and is connected to a displacer to change its reciprocating motion into rotary motion, A motion conversion mechanism for setting a lower limit is provided. The details are disclosed in JP-B-63-53469, so that illustration and description are omitted here.

The superconducting coils 11a and 11b are supported in the vacuum vessel 10 by a coil cooling heat conductor 13 as a winding frame. The coil cooling heat conductor 13 is formed of a material having a high heat conductivity such as copper or aluminum.

In this example, the refrigerator 12 comprises a first stage refrigeration stage 12-1 having a 50K first stage cold head 12-11 and a second stage refrigeration stage having a 4K second stage cold head 12-21. This is a two-stage refrigerator having a stage 12-2. The refrigeration stages 12-1 and 12-2 are located in the vacuum vessel 10, and particularly, the refrigeration stage 12-2 extends to near the connection portion 13-1 provided on the coil-cooling heat conductor 13. The second stage cold head 12-21 at the tip of the refrigeration stage 12-2 and the connection portion 13-1 are connected by a heat transfer member 14 having flexibility.

The vacuum vessel 10 has a double cylindrical structure capable of surrounding the periphery of the single crystal growing apparatus, and the coil cooling heat conductor 13 is also formed in a cylindrical shape. That is, the single crystal growth apparatus is arranged in a space formed inside vacuum chamber 10. The superconducting coils 11a and 11b
Two split-type coils for applying a caps-like magnetic field to molten silicon in a crucible of a single crystal growth apparatus. The superconducting coils 11a and 11b formed by these two split type coils are wound so as to be concentric with the center of the vacuum vessel 10 above and below the coil cooling heat conductor 13.

Further, two superconducting coils 11a and 11b
The heat conductor 13 for cooling the coil is connected to the refrigeration stage 12-
2 and the heat transfer member 14 are housed in a double cylindrical heat shield container 15 arranged in the vacuum container 10.
The heat shield container 15 is for preventing radiant heat from entering. Two superconducting coils 11a, 11b,
Coil cooling heat conductor 13 and heat shield container 15
Is supported by a plurality of load supports 16a and 16b provided at intervals in the circumferential direction at the top and bottom in the vacuum vessel 10.

Such a refrigerator-cooled superconducting magnet device is disclosed in Japanese Patent Application No. 10-5955.

A case where the embodiment of the present invention is applied to a portion corresponding to the load support 16b of the above-described refrigerator-cooled superconducting magnet device will be described.

FIG. 1 shows a refrigerator-cooled superconducting magnet apparatus to which the present invention is applied, on the right side of the apparatus shown in FIG. 4, and the same parts as those in FIG. 4 are denoted by the same reference numerals.

At the bottom of the vacuum vessel 10, load supports 16b made of GFRP are arranged at a plurality of locations at intervals in the circumferential direction. A support member 20 connects between each load support 16b and the coil cooling heat conductor 13.

As shown in FIGS. 2 and 3, the support member 20 has a structure in which a plurality of plates 21 are overlapped and their upper and lower ends are connected alternately. The upper and lower ends are connected by, for example, welding. A plate 21 on one end side (the left side in FIG. 2) of the structure is fixed to the coil cooling heat conductor 13 via a fixing bracket 22 with bolts or the like. The plate 21 on the other end side (the right side in FIG. 2) of the structure is welded and fixed to an L-shaped fixture 23 at the upper end. The fixture 23 is provided with a reinforced reinforcing plate 24.
The fixing bracket 23 is fixed to the upper end of the load support 16b.

The superconducting coils 11a and 11b and the heat conductor 13 for cooling the coil are accommodated in a double cylindrical heat shield container 15 in the vacuum container 10. The load support 16 b extends into the heat shield container 15 through an opening provided at the bottom of the heat shield container 15. In this example, the bottom of the heat shield container 15 and the load support 16b are connected by the supports 25-1 and 25-2 having the cylindrical Heim column structure described with reference to FIG. That is, the supports 25-1 and 25-2 are provided inside and outside the load support 16b.

For example, a superconducting coil 1 cooled to a very low temperature in a large superconducting magnet device having a diameter of about 2 m
The heat conductors 1a and 11b, the heat conductor 13 for cooling the coil, and the heat shield container 15 are shrunk by about 3 mm in the radius direction toward the center, and the load support that absorbs the deformation may have a structure to release the heat shrinkage. Required.

In this configuration, the heat shield container 15 is supported by a well-known Heim column structure, and the superconducting coils 11a,
The 1b side was configured to be supported by a support member 20 having an accordion structure in which stainless steel plates 21 were overlapped.

The structure of this superconducting magnet device has an inner diameter of about 16
It is based on a donut-shaped vacuum vessel having a diameter of 00 mm and an outer diameter of about 2100 mm. Vacuum container (stainless steel) 1
Inside 0, there is a heat shield container (copper) 15, which has the same donut shape as the vacuum container 15. Load support 1
Although the number of arrangements 6b is usually considered depending on the size of the heavy structure to be supported, in the case of the present embodiment, the arrangement is provided at eight locations at equal angles on the concentric circle with the vacuum vessel 10 and others.

The support member 20 having the accordion structure is characterized in that, as the superconducting coils 11a and 11b are cooled and thermally contracted toward the center, as shown in FIG. This is a mechanism for alleviating bending stress applied to 16b. The laminated plate structure of the accordion part is formed by laminating several square plates having a thickness of about 1 mm to 2 mm and welding the upper and lower ends alternately. In design, the thickness, the number of layers, and the vertical and horizontal dimensions of the plate 21 are determined according to the amount of heat shrinkage. Further, the spring force of the accordion portion is set to be smaller than the bending rigidity of the load support 16b.

With the above-described support structure, in the present embodiment, even in a superconducting magnet device in which thermal contraction of 3 mm or more per m occurs, the thermal contraction is sufficiently absorbed and the bending stress applied to the load support 16b is reduced. be able to. In the above embodiment, the upper load support 1 shown in FIG.
6a is unnecessary, but when the upper load support 16a is provided, a similar support structure is applied to the upper load support 16a.

According to the present invention, not only the large superconducting magnet device as described above, but also a vacuum container in a low-temperature device is provided.
Effective for supporting loads in heavy structures where large heat shrinkage occurs.Because only vertical loads do not apply lateral bending loads to load supports, the design rigidity of the load supports is not excessively increased. Accordingly, the amount of heat penetration can be reduced.

The superconducting coil (4.2K) and the heat shield container (50-70K) having the structure as in the above embodiment.
When supporting multiple structures that have a heat shield of
Since the space for the portion for supporting the superconducting coil is not taken up, the design can be simplified and economical.

[0042]

As described above, according to the present invention, it is possible to realize, with a simple structure, a support structure for a heavy structure which can be applied to a large superconducting magnet device which undergoes large deformation due to thermal contraction.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view when an embodiment of the present invention is applied to a refrigerator-cooled superconducting magnet device.

FIG. 2 is a view for explaining the operation of the support member shown in FIG. 1;

FIG. 3 is a top view of the support member shown in FIG. 1;

FIG. 4 is a longitudinal sectional view showing a refrigerator cooled superconducting magnet device to which the present invention is applied.

FIG. 5 is a longitudinal sectional view showing one example of a superconducting coil support structure in a conventional refrigerator-cooled superconducting magnet device.

FIG. 6 is a longitudinal sectional view showing another example of a superconducting coil support structure in a conventional refrigerator-cooled superconducting magnet device.

FIG. 7 is a diagram showing a Heime column support in FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Vacuum container 11a, 11b Superconducting coil 12 Refrigerator 12-1 First stage refrigeration stage 12-2 Second stage refrigeration stage 12-11 First stage cold head 12-21 Second stage cold head 12-22 Cold head Extension portion 13 Heat conductor for coil cooling 13-1 Connection portion 14 Heat transfer member 15 Heat shield container 16a, 16b Load support 20 Support member 21 Plate 22, 23 Fixture 24 Reinforcement plate 25-1, 25-2 Support

Claims (4)

[Claims] 1. A supporting structure for accommodating a heavy-weight structure in a low-temperature container and supporting the heavy-weight structure with a load support at a plurality of locations, wherein a plurality of load-supports are provided between the heavy-weight structure and the load supports. By superposing the plates and connecting them by a support member having a structure in which the upper and lower ends are alternately connected, the stress caused by the thermal shrinkage of the heavy structure due to the low temperature is reduced. A support structure for a heavy structure, characterized in that: 2. The support structure according to claim 1, wherein said low-temperature container is a double-cylinder container having an inner tube and an outer tube, and said weight structure is cylindrical. Support structure for things. 3. A supporting structure according to claim 2, wherein said low-temperature container is a vacuum container containing a superconducting coil and having a refrigerator for cooling said superconducting coil, and said heavy structure is formed of said superconducting coil. A coil and a coil-cooling heat conductor as a winding frame, wherein the load support and the coil-cooling heat conductor are arranged at a plurality of locations spaced apart in the circumferential direction at the bottom of the vacuum vessel. A support structure for a heavy structure, wherein the space is connected by the support member. 4. The support structure according to claim 3, wherein the superconducting coil and the coil cooling heat conductor are further housed in a heat shield container constituting a double cylindrical container in the vacuum container. The load support extends through the opening provided in the bottom of the heat shield container to the inside of the heat shield container. Between the bottom of the heat shield container and the load support, a support of the Heim column structure is provided. A support structure for a heavy structure, which is connected by a body.