JP4157424B2 - Refrigerator cooled superconducting magnet device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a refrigerator-cooled superconducting magnet device, and more particularly to a refrigerator-cooled superconducting magnet device having a refrigerator that cools a superconducting coil.
[0002]
[Prior art]
For example, when a silicon single crystal is grown using a magnetic field application type Czochralski method (MCZ method), a silicon single crystal is grown while applying a magnetic field to a silicon single crystal manufacturing apparatus (for example, Patent Document 1). The magnetic field is applied to the silicon single crystal manufacturing apparatus using a refrigerator-cooled superconducting magnet apparatus.
[0003]
FIG. 2 shows a refrigerator-cooled superconducting magnet device 100 (hereinafter referred to as a superconducting magnet device), which is a conventional example. The superconducting magnet device 100 is used when a silicon single crystal is grown using the MCZ method as will be described later.
[0004]
The superconducting magnet device 100 is roughly composed of a vacuum vessel body 111, a Gifford-McMahon refrigerator (hereinafter referred to as GM refrigerator), a heat shield plate 116, a superconducting coil 118, a refrigerator compressor 117, and the like.
[0005]
The heat shield plate 116 is provided in the vacuum container main body 111, and the GM refrigerator 113 is disposed in the vacuum container main body 111. The GM refrigerator 113 is connected to a refrigerator compressor 117 that compresses the refrigerant, and the refrigerant (for example, helium gas) compressed to a high pressure by the refrigerator compressor 117 is supplied to the GM refrigerator 113.
[0006]
This high-pressure refrigerant is expanded in the GM refrigerator 113 by a displacer (not shown) driven by a motor 113A, whereby the cold storage material provided in the GM refrigerator 113 is cooled. Moreover, the refrigerant | coolant which became low pressure by expanding is returned to the refrigerator compressor 117, and is pressure-increased again.
[0007]
The GM refrigerator 113 has a first-stage cooling cylinder 114A and a second-stage cooling cylinder 114B. The first-stage cooling cylinder 114A is thermally connected to the heat shield plate 116, and the second-stage cooling cylinder 114B is thermally connected to the cooling stage 115.
[0008]
Therefore, the GM refrigerator 113 cools the heat shield plate 116 to prevent external heat from entering the heat shield plate 116, and the superconducting coil 118 is connected to the GM refrigerator 113 (2 through the cooling stage 115. It is cooled below the critical temperature by the stage cooling cylinder 114B). Thereby, the superconducting coil 118 realizes a superconducting state.
[0009]
The vacuum vessel main body 111 has a cylindrical hollow cylinder 122 formed at the center thereof. The superconducting coil 118 is disposed around the hollow cylinder 122. Therefore, when the superconducting coil 118 is excited, a magnetic field is generated in the hollow cylinder 122 formed in the vacuum vessel main body 121, and thus the hollow cylinder 122 functions as a room temperature magnetic field space 123. A silicon single crystal manufacturing apparatus 130 for manufacturing a silicon single crystal by the MCZ method is disposed in the room temperature magnetic field space 123, and the silicon single crystal is manufactured in a magnetic field generated by the superconducting coil 118.
[0010]
[Patent Document 1]
JP 2001-302392 A (see paragraphs 0011 to 0012, FIG. 1)
[0011]
[Problems to be solved by the invention]
By the way, in the configuration in which the silicon single crystal manufacturing apparatus 130 is incorporated in the superconducting magnet apparatus 100 as described above, the silicon single crystal manufacturing apparatus 130 is located inside the superconducting magnet apparatus 100. When observing or putting silicon polycrystal into the crucible, it is necessary for the operator to stand on the top plate 112 of the vacuum vessel main body 111 as shown in the figure.
[0012]
However, in the conventional superconducting magnet device 100, since the GM refrigerator 113 is simply arranged in the vacuum vessel main body 111, the motor 113A is configured to protrude from the top plate 112 in a so-called bare state. . For this reason, in the conventional superconducting magnet device 100, the operator needs to work on the top plate 112 from which the motor 113A protrudes, which is problematic in terms of safety.
[0013]
On the other hand, the superconducting coil 118 generates a strong magnetic field with respect to the silicon single crystal manufacturing apparatus 130 disposed in the room temperature strong magnetic field space 123. The generated magnetic field is not limited to the room temperature strong magnetic field space 123, and a part of the generated magnetic field leaks to the outside of the room temperature strong magnetic field space 123 (hereinafter, this magnetic field is referred to as a leakage magnetic field).
[0014]
When this leakage magnetic field is applied to the motor 113A of the GM refrigerator 113, the stability of the motor 113A deteriorates due to this leakage magnetic field, or vibration occurs in the motor 113A. If the motor 113A becomes unstable, there is a possibility that proper cooling processing cannot be performed, and if vibration occurs, the silicon single crystal pulling processing by the silicon single crystal manufacturing apparatus 130 may be adversely affected. .
[0015]
The present invention has been made in view of the above problems, and provides a refrigerator-cooled superconducting magnet apparatus that can improve the safety of work on a vacuum vessel body and suppress the occurrence of malfunction of the refrigerator due to a leakage magnetic field. The purpose is to do.
[0016]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention is characterized by the following measures.
[0017]
The invention according to claim 1
A superconducting coil that is excited by power supplied through the electrodes;
A refrigerator driven by a motor to cool the superconducting coil;
A vacuum vessel in which the superconducting coil is housed and the refrigerator is attached;
In the refrigerator-cooled superconducting magnet device having
When the motor and the electrode are shielded and viewed in plan by being arranged on the top of the vacuum vessel so as to cover the motor and the electrode made of a magnetic material and projecting from the top of the vessel A shield cover formed so that the outer shape of the vacuum container is substantially equal to the shape of the vacuum container in plan view,
The top plate of the shield cover along with a flat surface, refrigerator cooling superconducting magnet apparatus according to configuration and the features having an intensity of the top plate portion of the shield cover as a work area of the human.
[0018]
According to the above invention, the cover made of a magnetic material is disposed so as to cover the motor protruding from the top plate of the container, so that the magnetic field generated by the superconducting coil is shielded by the cover and can be prevented from affecting the motor. . For this reason, it can be prevented that the motor does not rotate properly due to the magnetic field generated by the superconducting coil or the motor is vibrated.
[0019]
In addition, since the top plate of the cover is a flat surface, and the top plate of the cover has strength as a human work area, for example, the operator can use the top plate of the cover for maintenance or the like. Even if it gets on, it can ensure the safety of the operator.
[0021]
Further , since the cover is configured to cover the electrode protruding from the top plate of the container, the electrode can be prevented from interfering with the operator.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
[0023]
FIG. 1 shows a refrigerator-cooled superconducting magnet device 10 (hereinafter referred to as a superconducting magnet device) that is an embodiment of the present invention. The superconducting magnet device 10 is used when a silicon single crystal is grown using a magnetic field application type Czochralski method (MCZ method) as will be described later.
[0024]
The superconducting magnet device 10 is roughly composed of a vacuum vessel body 11, a Gifford-McMahon refrigerator (hereinafter referred to as GM refrigerator), a heat shield plate 16, a superconducting coil 18, a refrigerator compressor 17, a shield cover 25, and the like. Has been.
[0025]
The heat shield plate 16 is provided in the vacuum vessel main body 11, and the GM refrigerator 13 is disposed in the vacuum vessel main body 111. The GM refrigerator 13 is connected to a refrigerator compressor 17 that compresses the refrigerant, and the refrigerant (for example, helium gas) compressed to a high pressure by the refrigerator compressor 17 is supplied to the GM refrigerator 13.
[0026]
The high-pressure refrigerant is expanded in the cylinders 14A and 14B by a displacer (not shown) driven by a motor 13A provided in the GM refrigerator 13, and thereby a cold storage material provided in the GM refrigerator 13 Is cooled. Moreover, the refrigerant | coolant which became low pressure by expanding is returned to the refrigerator compressor 17, and is high-pressure again.
[0027]
The GM refrigerator 13 has a first-stage cooling cylinder 14A and a second-stage cooling cylinder 14B. The first-stage cooling cylinder 14A is thermally connected to the top plate 16A, and the second-stage cooling cylinder 14B is thermally connected to the cooling stage 15.
[0028]
Therefore, the GM refrigerator 13 cools the heat shield plate 16 to prevent external heat from entering the heat shield plate 16, and the superconducting coil 18 is connected to the GM refrigerator 13 (2 It is cooled below the critical temperature by the stage cooling cylinder 14B). Thereby, the superconducting coil 18 realizes a superconducting state.
[0029]
The vacuum vessel main body 11 has a cylindrical hollow cylinder 22 formed at the center thereof. A plurality of superconducting coils 18 are arranged so as to surround the hollow cylinder 22. The superconducting coil 18 is supplied with current via the lead 21. The lead 21 is connected to a wiring 19 at an end protruding from the top plate 12, and the wiring 19 is connected to a power source (not shown). The other end of the lead 21 extends to the inside of the heat shield plate 16 and is electrically connected to the superconducting coil 18.
[0030]
Therefore, when a current is supplied from the power source to the superconducting coil 18 via the wiring 19 and the lead 21 and the superconducting coil 18 is excited, a predetermined magnetic field is generated in the hollow cylinder 22 formed in the vacuum vessel main body 21, and thus this The hollow cylinder 22 functions as a room temperature magnetic field space 23. Although not shown, the lead 21 is configured such that external heat is not transmitted to the superconducting coil 18.
[0031]
On the other hand, a silicon single crystal manufacturing apparatus 30 for manufacturing a silicon single crystal by the MCZ method is disposed in the room temperature magnetic field space 23, and a silicon single crystal 36 (ingot) is manufactured in a magnetic field generated by the superconducting coils 18A to 18C. Is done. Here, the silicon single crystal manufacturing apparatus 30 will be briefly described.
[0032]
The superconducting magnet apparatus 10 according to the present embodiment has a configuration in which a silicon single crystal manufacturing apparatus 30 is provided in a room temperature strong magnetic field space 23. The superconducting magnet device 10 is configured such that a crucible 32, a heater 33, a piano wire 35 and the like are provided in a heating furnace 31.
[0033]
In order to manufacture an ingot of the silicon single crystal 36 using the superconducting magnet device 10, first, another crystal silicon piece (nugget) as a raw material of the silicon single crystal is loaded into the crucible 32 and heated and melted by the heater 33. Then, a seed crystal 34 is provided in advance at the tip of the piano wire 35, and this is brought into contact with other molten crystal silicon, and the piano wire 35 is pulled up while being rotated. As a result, a silicon single crystal 36 is formed below the seed crystal 34.
[0034]
At this time, in the MCZ method, a strong magnetic field is applied to the melt in the crucible 32. This is because by applying a magnetic field to the melt in the crucible 32, convection of the melt in the crucible 32 is suppressed, thereby reducing the amount of oxygen dissolved in the silicon single crystal 36. The superconducting magnet device 10 is used to generate a magnetic field to be applied to the melt in the crucible 32.
[0035]
Further, since the silicon single crystal manufacturing apparatus 30 is located inside the superconducting magnet apparatus 10, the operator is shown when observing the inside of the silicon single crystal manufacturing apparatus 30 or when putting silicon polycrystal into the crucible 32. As described above, it is necessary to work while standing at the upper part of the superconducting magnet device 10.
[0036]
Here, in the superconducting magnet device 10 according to the present embodiment, attention is paid to the upper part of the vacuum vessel body 11. In this embodiment, a shield cover 25 is disposed on the top plate 12 of the vacuum vessel body 11.
[0037]
The shield cover 25 is made of a magnetic material (for example, mild steel). The shield cover 25 is provided so as to cover the motor 13 </ b> A and the lead 21 of the GM refrigerator 13 protruding from the top plate 12 of the vacuum vessel body 11. The top plate portion 26 of the shield cover 25 is configured to be a flat surface.
[0038]
Specifically, the thickness of the shield cover 25 (the thickness in the vertical direction in the drawing) is configured to be larger than the protruding amount of the motor 13A from the top plate 12 and the protruding amount of the lead 21 from the lead 21. A motor storage chamber 27 and a wiring storage chamber 28 are formed inside the shield cover 25.
[0039]
The shield cover 25 also functions as a cover for performing magnetic shielding as will be described later. For this reason, the position opened to the outside of the motor storage chamber 27 and the wiring storage chamber 28 is the side surface of the top plate portion 26, and the size of the opening is set as small as possible.
[0040]
The motor storage chamber 27 is a recess for storing the motor 13A therein, and is formed to correspond to the position where the GM refrigerator 13 (motor 13A) is disposed. The wiring storage chamber 28 is a recess for storing the lead 21 and the wiring 19, and is formed so as to correspond to the arrangement position of the lead 21 and the wiring 19. Therefore, the shield cover 25 is configured to accommodate the motor 13A, the wiring 19 and the leads 21 therein, and thus the top plate portion 26 of the shield cover 25 can be made flat.
[0041]
In addition, the outer shape of the shield cover 25 when viewed in plan is substantially equal to the outer shape of the vacuum vessel body 11 when viewed in plan. A central opening 29 having the same diameter as the hollow cylinder 22 is formed at the central position of the shield cover 25. Therefore, even if the shield cover 25 is provided on the vacuum vessel main body 11, the shield cover 25 does not interfere with the silicon single crystal manufacturing apparatus 30.
[0042]
Furthermore, the shield cover 25 is configured to have strength as a work area for performing predetermined processing on the silicon single crystal manufacturing apparatus 30. Specifically, the shield cover 25 has a strength that does not cause deformation or the like even if a number of workers who ride on the top plate portion 26 ride on the shield cover 25 when processing the normal silicon single crystal manufacturing apparatus 30. I have it.
[0043]
As described above, the superconducting magnet device 10 according to the present embodiment is configured such that the shield cover 25 made of a magnetic material protrudes from the top plate 12 of the vacuum vessel body 11, specifically, the motor 13A, the wiring 19, and the leads. The magnetic field generated by the superconducting coil 18 is shielded by the shield cover 25.
[0044]
For this reason, it is possible to prevent the leakage magnetic field from adversely affecting the motor 13A, and thus it is possible to prevent the motor 13A from properly rotating due to the magnetic field generated by the superconducting coil 18, and the motor 13A from vibrating. .
[0045]
The top plate portion 26 of the shield cover 25 is a flat surface as described above. The top plate portion 26 of the shield cover 25 has strength as a human work area. Further, the motor storage chamber 27 and the wiring storage chamber 28 formed in the shield cover 25 are opened on the side surface of the shield cover 25 and are not opened in the top plate portion 26. For this reason, even if an operator gets on the top plate part 26 of the shield cover 25 for maintenance or the like, the safety of the operator can be ensured.
[0046]
In this embodiment, the shield 13 covers the motor 13A, the wiring 19, and the leads 21 that protrude from the top plate portion 26 of the vacuum vessel body 11. However, there are other configurations that protrude from the top plate portion 26. In some cases, these may be covered with the shield cover 25.
[0047]
In the present embodiment, a configuration in which the top plate portion 26 of the shield cover 25 is a completely flat surface is shown. However, as is apparent from the above description, even if the top plate portion of the shield cover 25 has irregularities, the irregularities are sufficient to ensure sufficient safety when the operator performs work on the top plate portion 26. If there exists, the top-plate part which has this unevenness | corrugation shall also be contained in the flat surface said by the invention which concerns on Claim 1. FIG.
[0048]
【The invention's effect】
As described above, according to the present invention, it is possible to prevent the motor from being adversely affected by the magnetic field generated by the superconducting coil, and even if the operator works on the top plate of the cover, sufficient safety for the operator is achieved. Can be secured.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a refrigerator-cooled superconducting magnet apparatus according to an embodiment of the present invention.
FIG. 2 is a configuration diagram of a refrigerator-cooled superconducting magnet device as an example of the prior art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Superconducting magnet apparatus 11 Vacuum container main body 12 Top plate 13 GM refrigerator 15 Cooling stage 16 Heat shield plate 18 Superconducting coil 21 Lead 23 Room temperature strong magnetic field space 25 Shield cover 26 Top plate part 27 Motor storage room 28 Wiring storage room 29 Center opening 30 Silicon single crystal manufacturing equipment

Claims (1)

A superconducting coil that is excited by power supplied through the electrodes;
A refrigerator driven by a motor to cool the superconducting coil;
A vacuum vessel in which the superconducting coil is housed and the refrigerator is attached;
In the refrigerator-cooled superconducting magnet device having
When the motor and the electrode are shielded and viewed in plan by being arranged on the top of the vacuum vessel so as to cover the motor and the electrode made of a magnetic material and projecting from the top of the vessel A shield cover formed so that the outer shape of the vacuum container is substantially equal to the shape of the vacuum container in plan view,
The top plate of the shield cover along with a flat surface, refrigerator cooling superconducting magnet apparatus according to configuration and the features having an intensity of the top plate portion of the shield cover as a work area of the human.

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