JP5481681B2 - Superconducting electromagnet - Google Patents

Description

  The present invention relates to a superconducting electromagnet, and more particularly to a superconducting electromagnet equipped with a cryogenic refrigerator.

  A superconducting electromagnet is a device that generates a strong magnetic field, and is used in a superconducting state in which a superconducting coil is cooled to a very low temperature and current flows in a state where there is no electrical resistance. Patent Documents 1 to 3 are prior art documents disclosing superconducting electromagnets. In the superconducting electromagnets described in Patent Documents 1 to 3, liquid helium is used to cool the superconducting coil.

  In recent years, there is Patent Document 4 as a prior art document that discloses a superconducting electromagnet capable of generating refrigeration at an absolute temperature of 4 K (Kelvin) capable of condensing liquid helium. In the superconducting electromagnet described in Patent Document 4, a 4K refrigerator is mounted to suppress evaporation of liquid helium.

Japanese Patent Laid-Open No. Sho 62-185384 JP-A-9-312210 JP-A-6-69029 JP-A-11-162726

  FIG. 6 is a schematic diagram showing a configuration of a conventional superconducting electromagnet. As shown in FIG. 6, the superconducting coil 2 is accommodated in the cryogenic refrigerant tank 3. Liquid helium 1 for cooling the superconducting coil 2 is stored in the cryogenic refrigerant tank 3. Superconducting coil 2 is immersed in liquid helium 1.

  A heat shield 4 for reducing radiant heat is disposed around the cryogenic refrigerant tank 3. A vacuum heat insulating tank 5 is disposed around the heat shield 4. The inside of the vacuum heat insulating tank 5 is kept at a high vacuum.

  The superconducting electromagnet is provided with a first pipe 7, one end of the first pipe 7 faces an atmosphere of helium gas evaporating in the cryogenic refrigerant tank 3, and the other end is attached to the vacuum heat insulating tank 5. Using the first pipe 7, liquid helium injection, helium gas exhaust, and lead attachment for exciting the superconducting coil 2 are performed.

  The superconducting electromagnet is provided with a refrigerator mounting cylinder 9, one end of the refrigerator mounting cylinder 9 faces an atmosphere of helium gas evaporating in the cryogenic refrigerant tank 3, and the other end is mounted on the vacuum heat insulating tank 5. Yes. A refrigerator 8 is inserted and fixed in the refrigerator mounting cylinder 9. The refrigerator 8 cools the heat shield 4 and the cryogenic refrigerant tank 3.

  The first pipe 7 has a check valve 10 for exhausting the helium gas evaporated from the liquid helium 1 and a rupture for exhausting the helium gas evaporated in large quantities when the superconducting coil 2 is quenched (superconducting breakdown). Valve 6 is mounted in parallel. The rupture valve 6 is set to operate at a higher operating pressure than the check valve 10.

  The superconducting electromagnet having the above configuration has a problem that the evaporation of liquid helium increases due to heat intrusion from the refrigerator when the refrigerator is stopped during transportation. Further, the superconducting electromagnet described in the above-mentioned prior art also has room for further improvement in suppressing the evaporation of liquid helium.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a superconducting electromagnet that can suppress the evaporation of the cryogenic refrigerant when the refrigerator is stopped.

  A superconducting electromagnet according to the present invention includes a superconducting coil, a cryogenic refrigerant tank, a heat shield, a vacuum heat insulating tank, a refrigerator mounting cylinder, a refrigerator, a first pipe, a heat insulating material, and a second pipe. The cryogenic refrigerant tank stores a superconducting coil and stores a cryogenic refrigerant for cooling the superconducting coil. The heat shield surrounds the cryogenic refrigerant tank to reduce radiant heat. The vacuum insulation tank surrounds the heat shield. One end of the refrigerator mounting cylinder faces the atmosphere of the cryogenic refrigerant gas that evaporates in the cryogenic refrigerant tank, and the other end is attached to the vacuum heat insulating tank. The refrigerator is inserted into the refrigerator mounting cylinder and cools the heat shield and the cryogenic refrigerant tank. The first pipe has one end facing the atmosphere of the cryogenic refrigerant gas that evaporates in the cryogenic refrigerant tank, and the other end is attached to the vacuum heat insulating tank to inject the cryogenic refrigerant and exhaust the cryogenic refrigerant gas. Used for. The heat insulating material is arranged in a gap fit in the insertion portion of the refrigerator in the refrigerator mounting cylinder when the refrigerator is removed. The second pipe communicates with the gap between the refrigerator mounting cylinder and the heat insulating material and is arranged to exhaust the cryogenic refrigerant gas.

  According to the present invention, evaporation of the cryogenic refrigerant gas can be suppressed by preventing sensible heat of the evaporated cryogenic refrigerant gas from entering the cryogenic refrigerant tank.

It is a schematic diagram which shows the state at the time of attachment of the refrigerator in the superconducting electromagnet which concerns on Embodiment 1 of this invention. It is a schematic diagram which shows the state at the time of removal of the refrigerator in the superconducting electromagnet which concerns on the same embodiment. It is a schematic diagram which shows the state at the time of removal of the refrigerator in the superconducting electromagnet which concerns on Embodiment 2 of this invention. It is a schematic diagram which shows the state at the time of removal of the refrigerator in the superconducting electromagnet which concerns on Embodiment 3 of this invention. It is an enlarged view of the V section shown in FIG. It is a schematic diagram which shows the structure of the conventional superconducting electromagnet.

Hereinafter, the superconducting electromagnet in Embodiment 1 based on this invention is demonstrated with reference to figures. In the following description of the embodiments, the same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated.
Embodiment 1
FIG. 1 is a schematic diagram showing a state when the refrigerator is attached to the superconducting electromagnet according to Embodiment 1 of the present invention. As shown in FIG. 1, a superconducting coil 2 is accommodated in a cryogenic refrigerant tank 3. Further, liquid helium 1 that is a cryogenic refrigerant for cooling the superconducting coil 2 is stored in the cryogenic refrigerant tank 3. Stainless steel was used as the material for the cryogenic refrigerant tank 3.

  Superconducting coil 2 is immersed in liquid helium 1. The superconducting coil 2 is formed using NbTi as a main material. In this embodiment, liquid helium 1 is used as the cryogenic refrigerant. However, any refrigerant that can bring the superconducting coil 2 into a superconducting state may be used, and the type of refrigerant is not limited to liquid helium. Nitrogen may be used.

  A heat shield 4 that surrounds the cryogenic refrigerant tank 3 and reduces radiant heat is disposed. Al is used as the material of the heat shield 4, but any material having a high thermal conductivity may be used, and Cu or an alloy thereof may be used. The heat shield 4 is thermally connected to the cryogenic refrigerant tank 3, a first pipe 7 described later, and a refrigerator mounting cylinder 9.

  A vacuum heat insulating tank 5 surrounding the heat shield 4 is arranged. The inside of the vacuum heat insulating tank 5 is kept at a high vacuum. Although GFRP (Glass Fiber Reinforced Plastics) is used as the material of the vacuum heat insulating tank 5, any material having a low thermal conductivity may be used, and the material is not limited to this.

  The superconducting electromagnet is provided with a first pipe 7, one end of the first pipe 7 faces an atmosphere of helium gas evaporating in the cryogenic refrigerant tank 3, and the other end is attached to the vacuum heat insulating tank 5. Specifically, one end of the first pipe 7 is attached to the upper part of the cryogenic refrigerant tank 3. Further, the other end of the first pipe 7 is attached to the upper part of the vacuum heat insulating tank 5. Stainless steel was used as the material of the first pipe 7.

  Using the first pipe 7, liquid helium injection, helium gas exhaust, and lead attachment for exciting the superconducting coil 2 are performed. A burst valve 6 is attached to the other end of the first pipe 7 for exhausting helium gas that evaporates in large quantities when the superconducting coil 2 is quenched. In the present embodiment, the burst valve 6 is attached to the first pipe 7, but it may be attached to the other end of the refrigerator mounting cylinder 9 described later.

  The superconducting electromagnet is provided with a refrigerator mounting cylinder 9, one end of the refrigerator mounting cylinder 9 faces an atmosphere of helium gas evaporating in the cryogenic refrigerant tank 3, and the other end is mounted on the vacuum heat insulating tank 5. Yes. Specifically, one end of the refrigerator mounting cylinder 9 is attached to the upper part of the cryogenic refrigerant tank 3. Further, the other end of the refrigerator mounting cylinder 9 is attached to the upper part of the vacuum heat insulating tank 5. As a material for the refrigerator mounting cylinder 9, carbon fiber reinforced resin (CFRP) was used.

  A refrigerator 8 is inserted into the refrigerator mounting cylinder 9. Specifically, an insertion portion 15 of the refrigerator 8 corresponding to the outer shape of the refrigerator 8 is formed at the other end of the refrigerator mounting cylinder 9. The refrigerator 8 is sealed by an O-ring (not shown) or the like so that there is no gap between the inner surface of the refrigerator mounting cylinder 9 and the outer surface of the refrigerator 8 when inserted in the insertion portion 15. Yes. The refrigerator 8 cools the heat shield 4 and the cryogenic refrigerant tank 3.

  FIG. 2 is a schematic diagram showing a state when the refrigerator is removed from the superconducting electromagnet according to the present embodiment. As shown in FIG. 2, in the present embodiment, the refrigerator 8 is removed from the insertion portion 15 of the refrigerator attachment cylinder 9 when the refrigerator is stopped, such as when the superconducting electromagnet is transported.

  The heat insulating material 11 is inserted into the insertion portion 15 after the refrigerator 8 is removed. The outer shape of the heat insulating material 11 has substantially the same shape as the outer shape of the portion inserted into the insertion portion 15 of the refrigerator 8. However, the outer shape of the heat insulating material 11 is formed to be slightly smaller than the outer shape of the refrigerator 8. In the present embodiment, CFRP is used as the material of the heat insulating material 11, but any material having a low thermal conductivity may be used, and the material is not limited thereto.

  In a state where the heat insulating material 11 is inserted into the insertion portion 15, a gap is formed between the heat insulating material 11 and the refrigerator mounting cylinder 9. In other words, the heat insulating material 11 is fitted in the insertion portion 15 of the refrigerator 8 in the refrigerator mounting cylinder 9.

  A second pipe 16 is connected to the other end of the refrigerator mounting cylinder 9. The second pipe 16 communicates with the gap between the refrigerator mounting cylinder 9 and the heat insulating material 11. A check valve 10 for exhausting the helium gas from which the liquid helium 1 has evaporated is attached to the second pipe 16. Stainless steel was used as the material for the second pipe. The check valve 10 is set to operate at a lower operating pressure than the rupture valve 6.

  With the above configuration, the helium gas evaporated when the refrigerator 8 is removed passes through the gap between the insertion portion 15 of the refrigerator mounting cylinder 9 and the heat insulating material 11 and is exhausted from the second pipe 16. Therefore, the refrigerator mounting cylinder 9 can be cooled by sensible heat of helium gas, and the heat intrusion into the cryogenic refrigerant tank 3 can be suppressed. As a result, the evaporation of the liquid helium 1 can be suppressed.

  In the superconducting electromagnet of the present embodiment, the amount of liquid helium evaporated thereafter can be reduced by utilizing the sensible heat of the helium gas evaporated when the refrigerator 8 is removed. Therefore, the evaporation of liquid helium can be suppressed while the refrigerator 8 is stopped.

  Further, the check valve 10 provided in the second pipe 16 prevents clogging of the gap between the insertion portion 15 and the heat insulating material 11 due to external air flowing into the insertion portion 15 of the refrigerator mounting cylinder 9 and freezing. can do. If the gap between the insertion portion 15 and the heat insulating material 11 is blocked, the rupture valve 6 is attached to the first pipe 7, so that the evaporated helium gas can be discharged, and safety is ensured. ing.

Hereinafter, the superconducting electromagnet in Embodiment 2 based on this invention is demonstrated with reference to figures.
Embodiment 2
FIG. 3 is a schematic diagram showing a state when the refrigerator is removed from the superconducting electromagnet according to Embodiment 2 of the present invention. As shown in FIG. 3, in the superconducting electromagnet according to Embodiment 2 of the present invention, the second pipe 16 is connected to the other end of the first pipe 7. Specifically, a part of the second pipe 16 is connected to the end of the first pipe 7 attached to the vacuum heat insulating tank 5. Further, the check valve 10 and the rupture valve 6 are attached to the second pipe 16. Other configurations are the same as those in the first embodiment, and thus description thereof will not be repeated.

  With the above configuration, the helium gas evaporated when the refrigerator 8 is removed passes through the gap between the insertion portion 15 and the heat insulating material 11 and the first pipe 7 and is exhausted from the second pipe 16. Therefore, the refrigerator mounting cylinder 9 and the first pipe 7 can be cooled by sensible heat of helium gas, and heat penetration into the cryogenic refrigerant tank 3 can be suppressed. As a result, the evaporation of the liquid helium 1 while the refrigerator 8 is stopped can be suppressed.

Hereinafter, the superconducting electromagnet in Embodiment 3 based on this invention is demonstrated with reference to figures.
Embodiment 3
FIG. 4 is a schematic diagram showing a state when the refrigerator is removed from the superconducting electromagnet according to Embodiment 3 of the present invention. FIG. 5 is an enlarged view of a V portion shown in FIG. As shown in FIGS. 4 and 5, in the superconducting electromagnet according to Embodiment 3 of the present invention, a spiral groove 13 is formed in a fitting portion with the insertion portion 15 of the heat insulating material 12.

  The outer surface of the heat insulating material 12 is in contact with the inner surface of the refrigerator mounting cylinder 9 in the insertion portion 15. Therefore, the helium gas passes through the gap 14 between the refrigerator mounting cylinder 9 and the heat insulating material 12 along the groove 13 and is exhausted from the second pipe 16. In this way, a channel for helium gas is formed by the groove 13. Since other configurations are the same as those in the first embodiment, description thereof will not be repeated. Note that, similarly to the second embodiment, the second pipe 16 may be connected to the other end of the first pipe 7.

  With the above-described configuration, it is possible to lengthen the flow path of the exhausted helium gas while ensuring the thermal contact between the heat insulating material 12 and the refrigerator mounting cylinder 9. And the refrigerator attachment cylinder 9 can be cooled. Therefore, heat penetration into the cryogenic refrigerant tank 3 can be suppressed. As a result, the evaporation of the liquid helium 1 while the refrigerator 8 is stopped can be suppressed. The shape of the groove portion 13 is not limited to a spiral shape, and may be any shape that can lengthen the flow path while securing the flow path of the helium gas.

  In addition, the said embodiment disclosed this time is an illustration in all the points, Comprising: It does not become a basis of limited interpretation. Therefore, the technical scope of the present invention is not interpreted only by the above-described embodiments, but is defined based on the description of the scope of claims. Further, all modifications within the meaning and scope equivalent to the scope of the claims are included.

  DESCRIPTION OF SYMBOLS 1 Liquid helium, 2 Superconducting coil, 3 Ultra low temperature refrigerant tank, 4 Heat shield, 5 Vacuum heat insulation tank, 6 Burst valve, 7 1st piping, 8 Refrigerator, 9 Refrigerator installation cylinder, 10 Check valve, 11, 12 Heat insulation Material, 13 groove part, 14 clearance gap, 15 insertion part, 16 2nd piping.

Claims (3)

A superconducting coil;
A cryogenic refrigerant tank that houses the superconducting coil and stores liquid helium that cools the superconducting coil;
A heat shield that surrounds the cryogenic refrigerant bath to reduce radiant heat;
A vacuum insulation tank surrounding the heat shield;
A refrigerator mounting cylinder having one end facing the atmosphere of helium gas evaporated in the cryogenic refrigerant tank and the other end attached to the vacuum heat insulating tank,
A refrigerator that is inserted into the refrigerator mounting cylinder and cools the heat shield and the cryogenic refrigerant tank;
One end faces the atmosphere of helium gas evaporated in the cryogen vessel, and the other end is attached to the vacuum thermal insulation vessel, and a first piping for exhausting the liquid helium injected and helium gas,
A heat insulating material fitted into a gap in the insertion portion of the refrigerator in the refrigerator mounting cylinder when the refrigerator is removed is arranged,
A superconducting electromagnet in which a second pipe for exhausting helium gas is disposed in communication with a gap between the refrigerator mounting cylinder and the heat insulating material.   The superconducting electromagnet according to claim 1, wherein the second pipe is connected to the other end of the first pipe.   The superconducting electromagnet according to claim 1 or 2, wherein a helical groove is formed in a fitting portion of the heat insulating material with the insertion portion.

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