JP5784536B2 - Superconducting coil cooling system - Google Patents

Description

  The present invention relates to a superconducting coil cooling system for conducting and cooling a superconducting coil housed in a vacuum vessel with a cryogenic refrigerator.

  In general, the superconducting coil needs to be cooled to a cryogenic temperature, and is cooled by a cryogen such as liquid helium or a cryogenic refrigerator. Therefore, the cooling cost is high, and this is one of the factors that limit the applied equipment.

  In recent years, high-temperature superconducting materials that become superconducting at a higher temperature than conventional metal-based superconducting materials have attracted attention. The high temperature superconducting material has a merit that the cooling cost is low because the cooling temperature is high. The high-temperature superconducting coil using this high-temperature superconducting material is used at a cooling temperature of about 20 to 40 K. However, since there is no suitable cryogen in this temperature range, conduction cooling is the mainstream.

  Since conduction cooling does not require a liquid helium container, there is an advantage that the configuration of the cooling system can be simplified. In addition, there is an advantage that the cost is reduced due to the simplification of the configuration. In particular, the second generation RE-based superconducting coil can be practically used even at a cooling temperature of 30K or higher. For this reason, in the superconducting coil cooling system, it is possible to further simplify by changing the configuration using the two-stage refrigerator as the cryogenic refrigerator to the configuration using the first-stage refrigerator (see, for example, Patent Document 1).

  FIG. 5 is an elevation view showing a configuration of a superconducting coil cooling system described in Patent Document 1 as a conventional superconducting coil cooling system.

  A conventional superconducting coil cooling system includes a superconducting coil 1, a cryogenic refrigerator 2, a coil heat transfer member 109 that thermally connects the superconducting coil 1 and the cryogenic refrigerator 2, and the periphery of the superconducting coil 1. To supply the current, the resin layer 3 to be covered, the radiation shielding layer 4 that covers the periphery of the resin layer 3, the vacuum container 7 that houses them, the support member 6 that supports the radiation shielding layer 4 in the vacuum container 7, and Current introducing terminal 8A, and a current lead 8B for electrically connecting the superconducting coil 1 and the current introducing terminal 8A.

  The cryogenic refrigerator 2 cools the current lead 8B. Furthermore, the cryogenic refrigerator 2 cools the superconducting coil 1 via the coil heat transfer member 109, thereby reducing the temperature difference between the superconducting coil 1 and the cryogenic refrigerator 2.

JP 2011-23702 A

  In the conventional superconducting coil cooling system, since the superconducting coil 1 and the cryogenic refrigerator 2 are thermally connected by the coil heat transfer member 109, when the cryogenic refrigerator 2 stops due to some trouble, the superconducting coil There was a problem that the temperature of 1 increased and the superconducting coil 1 was quenched. Here, when the cryogenic refrigerator 2 is stopped, the superconducting coil 1 is not cooled, and a large heat intrusion from the cryogenic refrigerator 2 is added, the coil temperature rapidly increases, and the superconducting coil 1 becomes short. Quench with time. When the superconducting coil 1 is quenched, the temperature of the superconducting coil 1 is significantly increased, and it takes time to recool. In the worst case, the superconducting coil 1 may be burned out.

  By the way, if there is a certain amount of time even if the cryogenic refrigerator 2 is stopped, quenching of the superconducting coil 1 can be avoided by reducing the energization current of the superconducting coil 1. Therefore, a mechanism is desired that slows the temperature rise of the superconducting coil 1 and can keep the temperature of the superconducting coil 1 below the operable temperature even after a certain period of time after the cryogenic refrigerator 2 is stopped.

  In addition, if there is a certain amount of time, there may be a merit by using this to continue the operation of the superconducting coil 1.

  As a method of keeping the temperature of the superconducting coil 1 below the operable temperature even after the cryogenic refrigerator 2 is stopped, increasing the heat capacity of the superconducting coil 1 can be considered. However, in this case, there is a problem that the initial cooling time of the superconducting coil 1 becomes long and the superconducting coil 1 becomes heavy.

  The problem to be solved by the present invention is to maintain the temperature of the superconducting coil below the operable temperature even for a fixed time when the cryogenic refrigerator is stopped due to some trouble.

A superconducting coil cooling system according to the present invention is a superconducting coil cooling system in which a superconducting coil housed in a vacuum vessel is conductively cooled by a refrigerator, and a resin layer covering the periphery of the superconducting coil and a radiation shielding covering the periphery of the resin layer. A heat transfer path for connecting the superconducting coil and the refrigerator directly, and a heat transfer means for the radiation shield layer that thermally connects the radiation shield layer and the refrigerator. It is characterized by not. Further, a superconducting coil cooling system according to another aspect of the present invention is a superconducting coil cooling system in which a superconducting coil housed in a vacuum vessel is conductively cooled by a refrigerator, and a resin layer covering the periphery of the superconducting coil; and A radiation shielding layer covering the surroundings, a radiation shielding layer heat transfer means for thermally connecting the radiation shield layer and the refrigerator, and a coil heat transfer for thermally connecting the superconducting coil and the refrigerator And a cross-sectional area of the heat transfer means for the coil is made smaller than a cross-sectional area of the heat transfer means for the radiation shielding layer, and the thermal resistance of the heat transfer means for the coil is reduced. It is characterized by being larger than the thermal resistance of the heating means .

  According to the present invention, when the cryogenic refrigerator is stopped due to some trouble, the temperature of the superconducting coil can be kept below the operable temperature even for a fixed time.

It is an elevational view showing the configuration of the superconducting coil cooling system according to the first embodiment of the present invention. It is an elevation view which shows the structure of the superconducting coil cooling system which concerns on 2nd Embodiment of this invention. It is an elevation view which shows the structure of the superconducting coil cooling system which concerns on 3rd Embodiment of this invention. It is a perspective view which shows the structure of the resin layer 3 of FIGS. It is an elevation which shows the structure of the conventional superconducting coil cooling system.

  Hereinafter, an embodiment of a superconducting coil cooling system according to the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is an elevation view showing the configuration of the superconducting coil cooling system according to the first embodiment of the present invention.

  The superconducting coil cooling system according to the first embodiment includes a superconducting coil 1, a cryogenic refrigerator 2, a resin layer 3, a radiation shielding layer 4, a radiation shielding layer heat transfer member 5, and a support member 6. A vacuum vessel 7, a current introduction terminal 8A, and a current lead 8B are provided.

  The vacuum container 7 is maintained in a vacuum state, and includes a superconducting coil 1, a cryogenic refrigerator 2, a resin layer 3, a radiation shielding layer 4, a radiation shielding layer heat transfer member 5, a support member 6, and a current lead 8B. A container to be accommodated. The current introduction terminal 8 </ b> A is provided outside the vacuum container 7.

  The shape of the superconducting coil 1 is a cylindrical shape, and the superconducting coil 1 shown in FIG.

  The current lead 8B has one end connected to the superconducting coil 1 and the other end connected to the current introduction terminal 8A. Thereby, the current lead 8B electrically connects the superconducting coil 1 and the current introduction terminal 8A. A current is introduced from the current introduction terminal 8A, and the current is supplied to the superconducting coil 1 through the current lead 8B.

  The resin layer 3 is provided so as to cover the periphery of the superconducting coil 1. The resin layer 3 has a function of mechanically supporting the superconducting coil 1 and a function as a heat insulating material having a large thermal resistance of a certain level or more. The resin layer 3 is preferably made of a material containing resin or fiber reinforced plastic (for example, epoxy resin).

  The radiation shielding layer 4 is provided so as to cover the periphery of the resin layer 3. The radiation shielding layer 4 shields radiation to the superconducting coil 1 in the vacuum vessel 7. The radiation shielding layer 4 is preferably made of aluminum or a material in which aluminum and fiber reinforced plastic are combined in the thickness direction, and the aluminum material is preferably of high purity (purity is 99% or more).

  One end of the support member 6 is attached to the vacuum vessel 7, and the other end is attached to the radiation shielding layer 4. Thereby, the support member 6 supports the radiation shielding layer 4 in the vacuum vessel 7.

  One end of the heat transfer member 5 for the radiation shielding layer is connected to the radiation shielding layer 4, and the other end is connected to the cryogenic refrigerator 2. As a result, the radiation shielding layer heat transfer member 5 thermally connects the radiation shielding layer 4 and the cryogenic refrigerator 2. The heat transfer member 5 for the radiation shielding layer is a heat transfer member in which an aluminum material is laminated in a direction perpendicular to the direction of heat conduction, and the aluminum material has a high purity (purity is 99% or more). It is desirable to be.

  The cryogenic refrigerator 2 is a refrigerator that generates cryogenic cold. The cryogenic refrigerator 2 directly cools the current lead 8B. Furthermore, the cryogenic refrigerator 2 cools the superconducting coil 1 from the radiation shielding layer heat transfer member 5 through the radiation shielding layer 4 and the resin layer 3.

  The operation of the superconducting coil cooling system according to the first embodiment will be described.

  First, the case where the cryogenic refrigerator 2 is operating will be described.

  The radiation heat penetration from the inside of the vacuum vessel 7 into the superconducting coil 1 and the heat conduction from the support member 6 to the superconducting coil 1 are blocked by the radiation shielding layer 4. Further, heat penetration from the current lead 8B into the superconducting coil 1 is blocked by the cryogenic refrigerator 2 directly cooling the current lead 8B.

  Thus, the heat load of the superconducting coil 1 is only minute heat generation of the superconducting coil 1 itself. For this reason, the cryogenic refrigerator 2 cools the superconducting coil 1 from the heat transfer member 5 for the radiation shielding layer through the radiation shielding layer 4 and the resin layer 3, thereby keeping the temperature of the superconducting coil 1 below the operable temperature. can do.

  Next, a case where the cryogenic refrigerator 2 is stopped due to some trouble will be described.

  When the cryogenic refrigerator 2 is stopped, high temperature enters the radiation shielding layer 4 from the cryogenic refrigerator 2, thereby increasing the temperature of the radiation shielding layer 4. At this time, since the resin layer 3 is provided between the radiation shielding layer 4 and the superconducting coil 1, high heat does not immediately enter the superconducting coil 1. However, when the temperature of the radiation shielding layer 4 rises to some extent, high heat enters the superconducting coil 1 from the cryogenic refrigerator 2 through the radiation shielding layer 4 and the resin layer 3.

  Here, in the conventional superconducting coil cooling system, since there is a heat transfer path (see the coil heat transfer member 109 in FIG. 5) that thermally connects the superconducting coil 1 and the cryogenic refrigerator 2, the cryogenic refrigerator. When 2 stops, high heat enters the superconducting coil 1 from the cryogenic refrigerator 2 immediately.

  On the other hand, in the superconducting coil cooling system according to the first embodiment, since a heat transfer path that directly connects the superconducting coil 1 and the cryogenic refrigerator 2 is not provided, the cryogenic refrigerator 2 immediately stops when the cryogenic refrigerator 2 stops. High heat does not enter the superconducting coil 1 from the refrigerator 2. Thereby, the temperature of the superconducting coil 1 can be kept below the operable temperature only for a certain time.

  The fixed time may be set to about 1 hour, for example, depending on the heat load, the thermal resistance of each heat transfer path, and the heat capacity of each part. This is a sufficient time to reduce the current of the superconducting coil 1, and the operational merit is great.

  As described above, according to the superconducting coil cooling system according to the first embodiment, when the cryogenic refrigerator 2 is stopped due to some trouble, the temperature of the superconducting coil 1 is kept below the operable temperature even for a fixed time. Can do.

  In the superconducting coil cooling system according to the first embodiment, a heat transfer member in which an aluminum material is laminated as the heat transfer member 5 for the radiation shield layer that thermally connects the radiation shield layer 4 and the cryogenic refrigerator 2. However, a cooling gas circulation system heat transfer member, specifically, a cooling gas of the cryogenic refrigerator 2 may be circulated to the radiation shielding layer 4 by a heat pipe or the like.

[Second Embodiment]
Only the changes from the first embodiment will be described for the superconducting coil cooling system according to the second embodiment. The same parts as those in FIG. 1 are denoted by the same reference numerals, and the parts not particularly described are the same as those in the first embodiment.

  FIG. 2 is an elevation view showing the configuration of the superconducting coil cooling system according to the second embodiment of the present invention.

  The superconducting coil cooling system according to the second embodiment further includes a coil heat transfer member 9 with respect to the configuration of the first embodiment.

  The coil heat transfer member 9 has one end connected to the superconducting coil 1 and the other end connected to the cryogenic refrigerator 2. Accordingly, the coil heat transfer member 9 thermally connects the superconducting coil 1 and the cryogenic refrigerator 2. Here, the heat resistance of the heat transfer member 9 for coil is larger than the heat resistance of the heat transfer member 5 for radiation shielding layer.

  The operation of the superconducting coil cooling system according to the second embodiment will be described.

  In the superconducting coil cooling system according to the first embodiment, there is a possibility that the superconducting coil 1 cannot be sufficiently cooled when a crack occurs in the bonding configuration between the resin layer 3 and the superconducting coil 1. In this case, the temperature of the superconducting coil 1 may rise and quench.

  Therefore, in the superconducting coil cooling system according to the second embodiment, a coil heat transfer member 9 for thermally connecting the superconducting coil 1 and the cryogenic refrigerator 2 is provided, and the cross-sectional area of the coil heat transfer member 9 is determined. It is smaller than the cross-sectional area of the heat transfer member 5 for the radiation shielding layer. That is, the heat resistance of the coil heat transfer member 9 is made larger than the heat resistance of the radiation shielding layer heat transfer member 5.

  Thereby, about the heat penetration | invasion to the superconducting coil 1 after the cryogenic refrigerator 2 stops, when the thermal resistance of the heat-transfer member 9 for coils is made the same as the heat resistance of the heat-transfer member 5 for radiation shielding layers It is much less than that.

  Further, even if a crack occurs in the bonding structure between the resin layer 3 and the superconducting coil 1, a minimum heat transfer path to the superconducting coil 1 is secured, so that the temperature immediately rises to a temperature at which the superconducting coil 1 quenches. do not do.

[Third Embodiment]
Only the changes from the first embodiment will be described for the superconducting coil cooling system according to the third embodiment. The same parts as those in FIG. 1 are denoted by the same reference numerals, and the parts not particularly described are the same as those in the first embodiment.

  FIG. 3 is an elevation view showing the configuration of the superconducting coil cooling system according to the third embodiment of the present invention.

  The superconducting coil cooling system according to the third embodiment further includes a thermal switch 10 with respect to the configuration of the first embodiment.

  The thermal switch 10 includes a first contact portion 10A, a second contact portion 10B, and an operation member 10C. One end of the operation member 10 </ b> C is connected to the first contact portion 10 </ b> A, and the other end is provided outside the vacuum container 7. At least the other end portion of the operation member 10C is a portion that is not thermally connected to the first contact portion 10A and is operated by an operator.

  In the present embodiment, the radiation shielding layer heat transfer member 5 is separated into a first radiation shielding layer heat transfer member 5A and a second radiation shielding layer heat transfer member 5B.

  The first radiation shielding layer heat transfer member 5 </ b> A has one end connected to the first contact portion 10 </ b> A and the other end connected to the cryogenic refrigerator 2. Thus, the first radiation shielding layer heat transfer member 5A thermally connects the first contact portion 10A and the cryogenic refrigerator 2.

  The second radiation shielding layer heat transfer member 5B has one end connected to the radiation shielding layer 4 and the other end connected to the second contact portion 10B. Thereby, the 2nd radiation shielding layer heat-transfer member 5B thermally connects the radiation shielding layer 4 and the 2nd contact part 10B.

  When the thermal switch 10 is turned on by the operator's operation, that is, when the first contact portion 10A and the second contact portion 10B of the thermal switch 10 are brought into contact with each other, the thermal switch 10 is changed from the first contact portion 10A to the first contact portion 10A. The cryogenic refrigerator 2 and the radiation shielding layer 4 are thermally connected from the second contact portion 10B via the second radiation shielding layer heat transfer member 5B via the first radiation shielding layer heat transfer member 5A.

  The operation of the superconducting coil cooling system according to the third embodiment will be described.

  In the superconducting coil cooling system according to the third embodiment, the thermal switch 10 is turned off when the cryogenic refrigerator 2 is stopped, that is, the first contact portion 10A and the second contact portion 10B of the thermal switch 10 are brought into contact with each other. By making it into the state which is not made, the heat | fever penetration | invasion from the cryogenic refrigerator 2 to the superconducting coil 1 can be interrupted | blocked, and the temperature rise of the superconducting coil 1 can be further delayed.

  Note that, in the superconducting coil cooling system according to the third embodiment, as an application example, the same effect as described above can be obtained even if the thermal switch 10 is further provided in the configuration of the second embodiment.

  In this case, first and second heat switches (not shown) are attached as heat switches 10 to the heat transfer member 5 for the radiation shielding layer and the heat transfer member 9 for the coil, respectively. The case where the first heat switch is attached to the radiation shielding layer heat transfer member 5 is the same as the case where the heat switch 10 is attached to the radiation shielding layer heat transfer member 5. When the second heat switch is attached to the coil heat transfer member 9, the coil heat transfer member 9 is separated into a first coil heat transfer member (not shown) and a second coil heat transfer member (not shown). Is done.

  The first coil heat transfer member has one end connected to the first contact portion 10A of the second heat switch and the other end connected to the cryogenic refrigerator 2 so that the first contact of the second heat switch. The unit 10A and the cryogenic refrigerator 2 are thermally connected. One end of the second coil heat transfer member is connected to the superconducting coil 1 and the other end is connected to the second contact portion 10B of the second thermal switch. The two contact portions 10B are thermally connected.

  When the second thermal switch is turned on by the operator's operation, that is, when the first contact portion 10A and the second contact portion 10B of the second thermal switch are brought into contact with each other, the second thermal switch is the second thermal switch. The cryogenic refrigerator 2 from the first contact portion 10A via the first coil heat transfer member and the superconducting coil 1 from the second contact portion 10B of the second heat switch via the second coil heat transfer member. Connect thermally.

  In the application example of the superconducting coil cooling system according to the third embodiment, when the cryogenic refrigerator 2 is stopped, the first and second thermal switches are turned off, that is, the first contacts of the first and second thermal switches. By making the part 10A and the second contact part 10B not contact each other, the heat intrusion from the cryogenic refrigerator 2 to the superconducting coil 1 can be cut off, and the temperature rise of the superconducting coil 1 can be further delayed.

[Fourth Embodiment]
Only the changes from the first to third embodiments will be described for the superconducting coil cooling system according to the fourth embodiment. Portions not particularly described are the same as those in the first to third embodiments.

  FIG. 4 is a perspective view showing the configuration of the resin layer 3 in FIGS. 1 to 3.

  The resin layer 3 has a hollow structure. Specifically, the heat insulating layer 3 has a panel configuration in which an end plate 12 is attached to a honeycomb member 11 of aramid fibers. Aramid fibers have high strength, and the strength is further increased by attaching plates on both sides.

  In the superconducting coil cooling system according to the fourth embodiment, since a load can be applied almost uniformly to the heat insulating layer 3, there is an effect that local stress is not applied to the superconducting coil 1.

[Other Embodiments]
As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, modifications, and features of the embodiments can be combined without departing from the spirit of the invention. . These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Superconducting coil 2 ... Cryogenic refrigerator 3 ... Resin layer 4 ... Radiation shielding layer 5 ... Radiation shielding layer heat transfer member 5A ... First radiation shielding layer heat transfer member 5B ... Second radiation shielding layer heat transfer member DESCRIPTION OF SYMBOLS 6 ... Support member 7 ... Vacuum container 8A ... Current introduction terminal 8B ... Current lead 9 ... Coil heat transfer member 10 ... Thermal switch 10A ... First contact part 10B ... Second contact part 10C ... Operation member 11 ... Honeycomb member 12 ... End plate 109 ... Heat transfer member for coil

Claims (8)

In a superconducting coil cooling system that conducts and cools a superconducting coil stored in a vacuum vessel with a refrigerator,
A resin layer covering the periphery of the superconducting coil;
A radiation shielding layer covering the periphery of the resin layer;
A heat transfer means for a radiation shielding layer for thermally connecting the radiation shielding layer and the refrigerator;
Equipped with,
A superconducting coil cooling system , wherein a heat transfer path for directly connecting the superconducting coil and the refrigerator is not provided . In a superconducting coil cooling system that conducts and cools a superconducting coil stored in a vacuum vessel with a refrigerator,
A resin layer covering the periphery of the superconducting coil;
A radiation shielding layer covering the periphery of the resin layer;
A heat transfer means for a radiation shielding layer for thermally connecting the radiation shielding layer and the refrigerator;
A coil heat transfer means for thermally connecting the superconducting coil and the refrigerator ;
Comprising
The cross-sectional area of the coil heat transfer means is made smaller than the cross-sectional area of the radiation shield layer heat transfer means, and the thermal resistance of the coil heat transfer means is larger than the heat resistance of the radiation shield layer heat transfer means. A superconducting coil cooling system. The heat transfer means for the radiation shielding layer is:
A heat transfer member for a radiation shielding layer capable of thermally connecting the radiation shielding layer and the refrigerator;
A heat switch for separating the heat transfer member for the radiation shielding layer when turned off;
The superconducting coil cooling system according to claim 1, wherein the superconducting coil cooling system is provided. The coil heat transfer means includes:
A heat transfer member for a coil capable of thermally connecting the superconducting coil and the refrigerator;
A thermal switch for separating the coil heat transfer member when turned off;
The superconducting coil cooling system according to claim 2, comprising:   The superconducting coil cooling system according to any one of claims 1 to 4, wherein the resin layer has a hollow structure.   The superconducting coil cooling system according to claim 5, wherein the resin layer includes a honeycomb member.   The superconducting coil cooling system according to claim 3, wherein the heat transfer means for the radiation shielding layer is a heat transfer member in which an aluminum material is laminated in a direction perpendicular to the direction of heat conduction.   The superconducting coil cooling system according to any one of claims 1 to 6, wherein the radiation shielding layer heat transfer means circulates a cooling gas of the refrigerator through the radiation shielding layer. .

Images