JP2018060926A - Superconducting magnet device - Google Patents

Abstract

In a conventional superconducting magnet device, when an abnormality occurs, it is necessary to stop the operation of the device after opening the exterior of the device and carrying out a repairing work until the vacuum is again drawn and cooled. Therefore, it was difficult to promptly move to the re-operation state. In order to solve the above problems, a superconducting magnet apparatus according to the present invention electrically connects a superconducting coil, a permanent current switch that forms a circuit with the superconducting coil, and the superconducting coil and the permanent current switch. A connection line that is connected to each other, a connection element that is a part of the connection line and formed from a plurality of connection elements that are independent of each other, a conduction cooling path that individually cools the plurality of connection elements, and the plurality of the plurality of connection elements A disconnecting means that is provided separately for each connection element and selectively disconnects the plurality of connection elements. [Selection] Figure 1

Description

  The present invention relates to a superconducting magnet device including a superconducting coil and a permanent current switch, and more particularly to a configuration for emergency demagnetization.

  In general, a superconducting magnet device needs a function for quickly demagnetizing (hereinafter referred to as emergency demagnetization) in order to cope with any abnormality that occurs during operation. In order to perform emergency demagnetization, it is common to consume magnetic energy as Joule heat in an element having electrical resistance. In particular, in order to perform emergency demagnetization during permanent current operation in which a current is captured in a superconducting closed circuit having a very low electrical resistance, it is necessary to generate an electrical resistance in the current path. In order to complete demagnetization promptly, it is effective to increase the electrical resistance as much as possible to increase Joule heat generation. However, in a superconducting magnet device using a high-temperature superconducting wire that has been practically used in recent years, it is difficult to obtain a large electrical resistance during a permanent operating current. This is because high-temperature superconducting wires generally have a lower normal propagation speed and a slower increase in electrical resistance than high-temperature superconducting wires such as niobium titanium wires, which are widely used. Because.

  As a method for solving this problem, a method is known in which a part of a superconducting closed circuit is disconnected at the time of emergency demagnetization and current is commutated to a protective resistor (for example, see Patent Document 1). If a part of the superconducting closed circuit is disconnected, a very large resistance can be obtained instantaneously, which is considered effective for emergency demagnetization of the high-temperature superconducting magnet device.

JP-A-3-278504

  In order to restart the superconducting magnet device after demagnetization by such a method, it is necessary to repair the disconnected portion. To repair the disconnection, raise the temperature inside the superconducting magnet device that has been cooled to room temperature, break the vacuum, introduce air into the device, open the exterior of the device, and perform repair work. Since it is necessary to stop the operation of the apparatus until the vacuum is drawn again to cool down, it is difficult to promptly shift to the re-operation state.

  In order to solve the above problems, a superconducting magnet device according to the present invention includes a superconducting coil, a permanent current switch that forms a circuit with the superconducting coil, and a connection that electrically connects the superconducting coil and the permanent current switch. A connection element formed of a plurality of connection elements that are part of the connection line and are independent of each other, a conduction cooling path that individually cools the plurality of connection elements, and the connection elements And disconnecting means for selectively disconnecting the plurality of connection elements.

  According to the present invention, even if a part of the superconducting circuit is disconnected due to emergency demagnetization, the superconducting closed circuit can be quickly constructed again.

It is the schematic of the superconducting magnet apparatus which concerns on 1st Embodiment. It is the schematic of the disconnection means which concerns on 1st Embodiment. It is the schematic of the cooling path switching mechanism which concerns on 1st Embodiment. It is the schematic of the superconducting magnet apparatus which concerns on 2nd Embodiment. It is the schematic of the cooling path switching mechanism which concerns on 3rd Embodiment.

  Hereinafter, modes for carrying out the present invention (hereinafter referred to as “embodiments”) will be described in detail with reference to the drawings. In each figure, common portions are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)
FIG. 1 is a schematic view of a superconducting magnet device 1 according to the first embodiment. The superconducting magnet device 1 includes a power source 2 and a cryocontainer 3. The cryocontainer 3 is provided with a refrigerator 4, and the member thermally connected to the refrigerator 4 is cooled below the superconducting transition temperature by operating the refrigerator 4 after evacuating the inside of the cryocontainer 3. I can do things. Inside the cryocontainer 3, a superconducting coil 5, a protective resistor 6, and a permanent current switch 7 are provided. Further, the superconducting coil 5 and the permanent current switch 7 are electrically connected by a connection line, and a part of the connection line includes a connection element 8 formed of a plurality of connection elements 8A, 8B, and 8C independent of each other. Is formed.

  The superconducting coil 5 and the protective resistor 6 are connected to the power source 2 in parallel. Of the two terminals at both ends of the permanent current switch 7, one end is connected to one end of the power source 2 in the same manner as the superconducting coil 5 and the protective resistor 6. The other end of the permanent current switch 7 is connected to a converging end of the connection element 8 made of a superconducting wire (in FIG. 1, the parts to which the connection elements 8A, 8B, and 8C are connected respectively). The connection element 8 includes a plurality of connection elements 8A, 8B, and 8C connected in parallel to each other, and one of the two terminals is connected to one end of the permanent current switch 7 as described above. The other end of the connection element 8 is connected to a terminal different from the side to which the permanent current switch 7 is connected, of the two terminals of the power supply 2. Thereby, a closed circuit is formed by the superconducting coil 5, the permanent current switch 7, and the connection element 8. Since each element is composed of a superconducting wire, it becomes a superconducting closed circuit capable of permanent current operation by making a superconducting transition.

  Each of the connection elements 8 is provided with disconnection means 9 (in FIG. 1, three disconnection means 9A, 9B, and 9C are shown). The disconnection means 9 is connected to the control device 10, and the normal conduction transition is performed by applying, for example, heat, a magnetic field, or a mechanical shock to any of the connection elements that are part of the connection element 8. It has a function to make it. As an example, FIG. 2 shows the vicinity of the disconnection means 9 in the case where a mechanism is adopted in which the connection element 8A is subjected to normal conduction transition by heat input by the heater 20. By closely winding the heater 20 around the connection element 8A, Joule heat at the time of energization can be efficiently input to the connection element 8A.

  For the connection element, it is desirable to use a wire that can easily rise in temperature when Joule heat is generated, for convenience in disconnection operation. Specifically, a sheath material (a normal material which is spread around the filament of the superconducting material among the constituent materials of the wire) has a low thermal conductivity and a high resistivity. For example, as the sheath material, cupronickel (CuNi), monel, or gold-silver alloy having low thermal conductivity and high resistivity compared to copper and silver used for general superconducting wires may be used. desirable. In particular, the portion of the connecting element in which the disconnection means 9 is provided is designed to reduce the outflow of heat to the surroundings so that the temperature easily rises when heat is generated. Specifically, for example, the connection element is surrounded by a resin material so that a member having a high thermal conductivity such as copper or aluminum or a member having a large heat capacity does not directly contact the connection element.

  Each of the connection elements 8A, 8B, and 8C is provided with a conduction cooling unit 11 (three conduction cooling units 11A, 11B, and 11C are shown in FIG. 1). The conduction cooling unit 11 constitutes a part of the conduction cooling path 12 (three conduction cooling paths 12A, 12B, and 12C are shown in FIG. 1) and is connected to the refrigerator 4 through the conduction cooling path 12. Thus, the connection elements 8A, 8B, and 8C can be cooled to a superconducting state. In the following, when there are a plurality of similar members and the same configuration and operation are exhibited, the notation of A, B, C, etc. is omitted, and only the numerals are attached. Further, the connection element 8 is simply referred to as the connection element 8 in the description of the structure corresponding to the individual connection element.

  In the middle of the plurality of conduction cooling paths 12, a conduction cooling path connection part 14 (three conduction cooling path connection parts 14A, 14B, and 14C are shown in FIG. 1) is provided. When the conduction cooling path connection portion 14 is closed, the connection element 8 is thermally connected to the refrigerator 4 through the conduction cooling path 12 and is cooled to be in a superconducting state. When the conduction cooling path connection portion 14 is open, the connection element 8 is not cooled and is in a normal conduction state even during operation of the superconducting magnet device 1.

  The superconducting magnet device 1 is provided with a cooling path switching mechanism 13 and can individually switch between opening and closing of the plurality of conduction cooling path connecting portions 14. This switching function is configured to be controlled from outside the cryocontainer 3 by any mechanical or electromagnetic method.

  As an example, FIG. 3 shows a schematic cross-sectional view of a specific configuration of the cooling path switching mechanism 13 in the case where switching of the conduction cooling path connection unit 14 is performed by a mechanical method. In FIG. 3, as an example, two conductive cooling path connection portions 14 </ b> A in a closed state and a conductive cooling path connection portion 14 </ b> B in an open state are illustrated. The connection element 8 is routed along the conduction cooling unit 11 so that the contact area is increased or the thermal resistance between the two is reduced by soldering or welding. The conduction cooling unit 11 is fixed to the vacuum vessel outer wall 34 via the support column 30. The support column 30 is made of a material having low thermal conductivity and high strength (for example, FRP material). The length and cross-sectional area of the support column 30 are determined so as to have sufficient thermal resistance, and the heat entering from the outer wall 34 of the vacuum vessel can be removed by the action of the refrigerator 4. An end portion of the cooling terminal 35 is thermally connected to the refrigerator 4 via the conduction cooling path 12, and is supported by the vacuum vessel outer wall 34 via the spring member 31. Due to the expansion and contraction action of the spring member 31, the cooling terminal 35 can move between the conduction cooling unit 11 and the vacuum vessel outer wall 34. The cooling terminal 35 is provided with a load transmission member 32, and the load transmission member 32 is joined to a vacuum sealing member 36. The load transmission member 32 protrudes to the atmosphere side through a through hole 37 formed in the outer wall 34 of the vacuum vessel, and the through hole 37 is closed by being covered with a bellows 33 and a vacuum sealing member 36. The internal vacuum is maintained. The vacuum sealing member 36 is connected to the vacuum vessel outer wall 34 via the bellows 33, and can be moved between the atmosphere side and the vacuum side by the expansion and contraction function of the bellows 33.

  Thereby, the load applied to the vacuum sealing member 36 from the atmosphere side can be transmitted to the cooling terminal 35 via the load transmission member 32.

  That is, the conduction cooling path 12 of this embodiment is in contact with the connection terminal 8 and the cooling terminal 35 whose end is connected to the refrigerator 4, the load transmission member 32 that is a load receiving portion that receives a mechanical load. A conduction cooling path connecting portion 14 composed of a conduction cooling portion 11 provided in the cooling terminal 35, and the cooling terminal 35 and the conduction cooling portion 11 are thermally connected by the force received by the load receiving portion. The connection elements can be individually cooled.

  Further, by utilizing the expansion and contraction action of the spring member 31, the cooling terminal 35 is configured to be separated from the conduction cooling unit 11 when no load is applied from the atmosphere side. In this case, the conduction cooling path connection portion 14 is opened. By applying a load to the vacuum sealing member 36 from the atmosphere side, the cooling terminal 35 and the conduction cooling part 11 can be brought into contact with each other, and the conduction cooling path connection part 14 can be closed. As described above, the conduction cooling path connection portion 14 can be easily opened and closed from the outside of the cryocontainer 3, and it is also possible to control which conduction cooling path 12 is operated effectively.

  Next, a procedure until a current is passed through the superconducting closed circuit and a permanent current operation is performed will be described. Using the cooling path switching mechanism 13, only one of the plurality of conduction cooling path connections 14 is closed and the others are open. In the following, a case where the conduction cooling path connection portion 14A is closed as an example will be described, but the same applies when another conduction cooling path connection portion is selected. As shown in FIG. 1, the connection element 8 includes connection elements 8B and 8C in addition to the connection element 8A. Even if the number of connecting elements 8 is different from that in FIG.

  In the situation as described above, only one connecting element 8A is thermally connected to the refrigerator 4 and is cooled to be in a superconducting state. Since the other connecting elements are not cooled by the refrigerator 4, they are in a normal conduction state.

When supplying current from the power source 2 to the superconducting coil 5, first, the permanent current switch 7 is turned off (open, open) so that an excessive current does not flow into the permanent current switch 7 and the connecting element 8 due to the voltage generated at both ends thereof. Normal conduction state). Thereafter, a current is supplied from the power source 2 to the superconducting coil 5, and after reaching a desired current value, the permanent current switch 7 is cooled and turned on (open, superconducting state). After that, by making the supply current of the power source 2 zero, a current flows through a superconducting closed circuit having a zero resistance consisting of the superconducting coil and the permanent current switch 7. At this time, the superconducting magnet device performs a permanent current operation in which the magnetic field is maintained for a long time without supplying current from the outside. In addition, since the connection elements 8B and 8C other than the connection element 8A that is cooled and in the superconducting state are in a normal conduction state and have electric resistance, no current flows during the permanent current operation.
Next, an operation for performing emergency demagnetization during the permanent current operation will be described. In order to carry out emergency demagnetization, the controller 10 is operated to operate the disconnection means 9A provided in the connection element 8A cooled by the refrigerator 4. As a result, the connection element 8A undergoes normal conduction transition and Joule heat is generated. Since the temperature around the disconnection means 9 in the connecting element 8 is likely to rise due to the generation of Joule heat, the connection element 8 can be melted quickly.

  As described above, the current flowing through the permanent current switch 7 and the connection element 8A during the permanent current operation flows into the other lower resistance elements (protection resistance 6, connection elements 8B, 8C). By generating Joule heat in each element, the magnetic energy held by the superconducting coil 5 is consumed, and demagnetization is completed. The current value flowing into each element increases as the resistance decreases, but the shape and material of each element are designed so as to have a sufficient resistance value and heat capacity so as not to be burned by Joule heat generated thereby.

Next, a description will be given of a method for returning the apparatus to make it possible to operate again after emergency demagnetization. By operating the cooling path switching mechanism 13, the conduction cooling path connection section 14A that has thermally connected the disconnected connection element 8 and the refrigerator 4 is opened, and another conduction cooling path connection section (for example, a conduction cooling path) is opened. Only one connection 14B is closed. By doing so, the connection element 8B can be cooled via the conduction cooling path 12B to be in a superconducting state. Since this switching operation can be easily realized by operating the cooling path switching mechanism 13 from the outside of the refrigerator, the inside of the freezing container 4 is raised in temperature, the vacuum is broken, and further specialized knowledge is possessed. There is no need to invite workers. Thereby, the superconducting coil 5, the permanent current switch 7, and the connecting element 8B can constitute a superconducting closed circuit, and the above-described method for putting into permanent current operation can be executed again.
In addition, whenever the emergency demagnetization by this method is implemented, the several connection element 8 is fuse | melted one by one. If all the connecting elements 8 are consumed and the melted connecting elements 8 are reconnected, for example, when the temperature of the inside of the cryocontainer 3 is increased, for example, scheduled maintenance of the apparatus, emergency demagnetization can be performed any number of times. Can be implemented.

<Action and effect>
As described above, the superconducting magnet device 1 according to the first embodiment includes the plurality of connection elements 8 between the permanent current switch 7 and the superconducting coil 5, and switches the cooling path of the connection elements from the outside of the cryocontainer 3. With this configuration, even if the connection element 8 is blown during emergency demagnetization, the superconducting magnet device 1 can be quickly and easily re-operated by switching the cooling path from the blown connection element. I can do it. Also, in the past, it was necessary to invite personnel with specialized skills to obtain the extremely small resistance required for permanent current operation in the work of reconnecting the disconnection point. According to an example, the frequency can be reduced.

(Second Embodiment)
Next, the superconducting magnet device 1 according to the second embodiment will be described. FIG. 4 is a schematic view of the superconducting magnet device 1 according to the second embodiment. The superconducting magnet device 1 according to the second embodiment differs from the superconducting magnet device 1 according to the first embodiment in the arrangement of the permanent current switch 7. Since the other configuration of the superconducting magnet device 1 according to the second embodiment is the same as that of the superconducting magnet device 1 according to the first embodiment, description thereof will be omitted.

  In the superconducting magnet device 1 according to the second embodiment, the plurality of connection elements 8 (connection elements 8A, 8B, 8C in FIG. 4) also serve as the permanent current switch 7 (in FIG. 4, permanent current switches 7A, 7B, 7C). Apart from this, the permanent current switch 7 is not provided.

  As described in the description of the method of performing the operation of emergency demagnetization, current flows through the connection element 8 that is not cooled during emergency demagnetization. At that time, the amount of generated Joule heat increases as the electrical resistance decreases. Therefore, it is necessary to sufficiently increase the resistance value of the connection element 8 based on the magnetic energy and demagnetization time of the superconducting coil. On the other hand, the role of the permanent current switch 7 is to suppress the current flowing into the permanent current switch 7 even if an induced voltage is generated at both ends of the superconducting coil at the time of excitation due to the electrical resistance in the off state (open, normal conduction state). is there. This function can be realized by causing each of the plurality of connection elements 8 to transition from the superconducting state to the normal conducting state so that a resistance sufficient to suppress the current flowing during excitation is generated.

  With the above configuration, the plurality of connection elements 8 also serve as the permanent current switch 7, and it is not necessary to add the permanent current switch 7 separately.

<Action and effect>
As described above, in the superconducting magnet device 1 according to the second embodiment, not only the same effect as the superconducting magnet device 1 according to the first embodiment is obtained, but the connection element 8 also serves as the permanent current switch 7. Thus, it is not necessary to provide the permanent current switch 7 separately from this, and the superconducting magnet device 1 can be simply configured.

(Third embodiment)
Next, the superconducting magnet device 1 according to the third embodiment will be described. FIG. 5 is a schematic cross-sectional view of the cooling path switching mechanism 13 according to the third embodiment. The superconducting magnet device 1 according to the third embodiment is different in the configuration of the cooling path switching mechanism 13 from the configuration of the superconducting magnet device 1 according to the first embodiment. Since the other structure of the superconducting magnet apparatus 1 which concerns on 3rd Embodiment is the same as the superconducting magnet apparatus 1 which concerns on 1st Embodiment, description is abbreviate | omitted.

  The cooling path switching mechanism 13 according to the third embodiment is different from that in the first embodiment in that it operates with electromagnetic force. That is, in the conduction cooling path connecting portion 14 according to the first embodiment, the load is transmitted to the load transmission member 32 in order to move the cooling terminal 35, but this role is achieved in the third embodiment. Instead of the load transmission member 32, the electromagnet 38 is used. The electromagnet 38 is provided in the cooling terminal 35 and applies an electromagnetic force when energized to control opening and closing of the conduction cooling path connection portion 14. More specifically, the conduction cooling path 12 in this embodiment includes a cooling terminal 35 having an end connected to the refrigerator, a conduction cooling unit 11 provided so as to contact the connection element 8, and a cooling terminal 35. A conductive cooling path connecting portion 14 configured to thermally connect the cooling terminal 35 and the conductive cooling portion 11 by electromagnetic force generated when the electromagnet 38 is energized. Have The conductive cooling path connection portion 14 can selectively cool the connection element 8.

  In order to apply an electromagnetic force to the electromagnet 38, it is necessary to apply a magnetic field to the electromagnet 38. For this purpose, the magnetic field is generated by providing another electromagnet, or a permanent magnet is installed, or superconductivity is provided. A magnetic field generated by the coil 5 is used.

  With the above configuration, compared to the cooling path switching mechanism 13 according to the first embodiment, the vacuum vessel outer wall 34 is provided with a through hole 37, and further, a vacuum holding member such as a vacuum sealing member 36 or a bellows 33 is provided. It is not necessary to provide a member for this purpose. Further, the load transmission member 32 according to the first embodiment is not necessary, and heat intrusion via the load transmission member 32 can be eliminated, so that the amount of heat intrusion from the atmosphere into the freezing container 3 can be reduced.

<Action and effect>
Thus, in the superconducting magnet device 1 according to the third embodiment, not only the same effect as the superconducting magnet device 1 according to the first embodiment can be obtained, but it is not necessary to provide a through hole in the outer wall of the device, The magnet device 1 can be configured simply, and the amount of heat penetration from the atmosphere into the freezing container 3 can be reduced.

DESCRIPTION OF SYMBOLS 1 Superconducting magnet apparatus 2 Power supply 3 Freezing container 4 Refrigerator 5 Superconducting coil 6 Protection resistance 7 Permanent current switch 8 Connection element 8A, 8B, 8C Connection element 9A, 9B, 9C Disconnection means 10 Controller 11A, 11B, 11C Conduction cooling part 12A, 12B, 12C Conductive cooling path 13 Cooling path switching mechanism 14A, 14B, 14C Conductive cooling path connection portion 20 Heater 30 Support column 31 Spring member 32 Load transmitting member (load receiving portion)
33 Bellows 34 Vacuum vessel outer wall 35 Cooling terminal 36 Vacuum sealing member 37 Through hole 38 Electromagnet

Claims (5)

A superconducting coil;
A permanent current switch forming a circuit with the superconducting coil;
A connection line for electrically connecting the superconducting coil and the permanent current switch;
A part of the connection line, a double-lined part formed from a plurality of connection elements independent of each other;
Conductive cooling means for individually cooling the plurality of connecting elements;
Disconnection means provided separately for the plurality of connection elements, and selectively disconnecting the plurality of connection elements;
A superconducting magnet device comprising: The superconducting magnet device according to claim 1,
2. The superconducting magnet device according to claim 1, wherein the permanent current switch is individually provided for each of the connection elements. The superconducting magnet device according to claim 1 or 2, wherein
The plurality of disconnection means are electric heaters wound around the connection element, and the connection element is fused by energization. The superconducting magnet device according to any one of claims 1 to 3,
The conduction cooling means includes
A cooling terminal having an end connected to the refrigerator;
A load receiving portion for receiving a mechanical load;
A conduction cooling part provided to come into contact with the connection element;
With
The superconducting magnet apparatus, wherein the cooling terminal and the conduction cooling unit are thermally connected by a force received by the load receiving unit. The superconducting magnet device according to any one of claims 1 to 3,
The conduction cooling means includes
A cooling terminal having an end connected to the refrigerator;
A conduction cooling part provided to come into contact with the connection element;
An electromagnet to which the cooling terminal is fixed;
With
The superconducting magnet apparatus, wherein the cooling terminal and the conduction cooling unit are thermally connected by electromagnetic force generated by energizing the electromagnet.

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