JP7458274B2 - superconducting electromagnet - Google Patents

Description

Embodiments of the present invention relate to superconducting electromagnets that are cooled by thermal conduction.

Liquid helium immersion has traditionally been the mainstream method for cooling superconducting electromagnets, which generate induced magnetic fields by circulating persistent currents. In recent years, a heat conduction method that conducts cold heat supplied from a cryogenic refrigerator to a superconducting electromagnet has been studied. In either of these two systems, a persistent current switch (PCS) is used when starting the superconducting electromagnet. That is, the persistent current switch is set to OFF, and an exciting current is supplied from the power source to generate an induced magnetic field in the main coil (driven mode). Thereafter, the persistent current switch is switched to the ON setting, and the supply of excitation current is gradually reduced to shift to persistent current mode (PC mode).

The persistent current switch is equipped with a non-inductively wound coil of superconducting wire and a heater wire. The non-inductively wound coil, which is in a cooled state, is heated/removed from the heat to switch between a normal conductive state and a superconductive state, thereby setting the persistent current switch to OFF/ON.

When cooling is performed using a liquid helium immersion method, the heat generated when the persistent current switch is set to OFF is dissipated into the liquid helium coolant except for raising the temperature of the non-inductively wound coil. Therefore, there was no particular need to consider the effect of heat generation when the persistent current switch is set to OFF on the main coil and the lead wire.

Publication No. 2018-010948

However, when cooling is performed using a heat conduction method, part of the heat generated when the persistent current switch is set to OFF reaches the main coil. There is a concern that the temperature of the main coil and the leader wire will rise due to this reached heat, exceeding the critical point of superconductivity and leading to normal conduction transition (quench).

Furthermore, while pure copper is used for the matrix of the superconducting wire of the main coil, a high-resistance alloy (CuNi) is used for the matrix of the superconducting wire of the persistent current switch. This is to suppress current shunting to the persistent current switch and generate a sufficient induced magnetic field in the main coil in the above-mentioned driven mode.

By the way, a wire having a CuNi matrix has lower stability than a superconducting wire having a copper matrix, and is more likely to be quenched due to magnetic instability. For this reason, when the persistent current switch is cooled by the thermal conduction method, the instability of the leader wire of the persistent current switch becomes more significant than when cooling by the liquid helium immersion method. Furthermore, even a low current value that is below the equipment's rating increases the risk of quenching.

The embodiment of the present invention was made in consideration of these circumstances, and aims to provide a superconducting electromagnet that reduces the risk of quenching when cooled using a thermal conduction method.

A superconducting electromagnet according to an embodiment of the present invention comprises: a main coil that generates an induced magnetic field; a persistent current switch that forms a closed circuit with the main coil and is switchable between a normal conducting state and a superconducting state; a first lead wire and a second lead wire that are drawn from a non-inductive winding coil of the persistent current switch and connected to each of end wires on both sides of the main coil; a heat transfer member that supports the main coil and transfers cold generated by a cryogenic refrigerator to the main coil; a support member having one end connected to the heat transfer member and the other end that supports the persistent current switch and forms a main path of the cold transferred to the persistent current switch; and a separation structure that separates, in the support member, a first portion with which the first lead wire is in electrical contact and a second portion with which the second lead wire is in electrical contact along the longitudinal direction, wherein the heat transfer member and the support member are electrically insulated .

Embodiments of the present invention provide a superconducting electromagnet that reduces the risk of quenching when cooled by thermal conduction.

FIG. 1 is a configuration diagram showing a longitudinal section of a superconducting electromagnet according to an embodiment of the present invention. (A) A vertical cross-sectional view of a portion of the superconducting electromagnet shown in area A in FIG. 1, and (B) a top view thereof. A circuit diagram of a superconducting electromagnet according to an embodiment. (A) A conceptual diagram showing a cross section of a superconducting wire of a main coil, and (B) a conceptual diagram showing a cross section of a superconducting wire of a persistent current switch. 1 is a graph showing changes in electrical resistance values with respect to temperature of a superconductor and a matrix body that constitute a superconducting wire. 1 is a graph illustrating three critical points (critical current Ic, critical temperature Tc, critical magnetic field Hc) in the superconducting state. (A) (B) (C) (D) Graphs explaining the excitation process of a superconducting electromagnet. Side view of electrical connections. (A) (B) Cross-sectional views of the first leader line and the second leader line arranged on the support member. (A) A vertical cross-sectional view of a persistent current switch (first example) supported by a support member, and (B) a bottom view thereof. (A) A side view of a persistent current switch (second example) supported by a support member, (B) a horizontal sectional view thereof. FIG. 1A is a side view showing a first example of a support member, and FIG. 1B is a side view showing a second example of a support member.

Embodiments of the present invention will be described below based on the accompanying drawings. FIG. 1 is a configuration diagram showing a longitudinal section of a superconducting electromagnet 10 according to an embodiment of the present invention. FIG. 2(A) is a longitudinal cross-sectional view of a portion of the superconducting electromagnet 10 shown in area A in FIG. FIG. 2(B) is a top view thereof.

The superconducting electromagnet 10 thus comprises a main coil 15 that generates an induced magnetic field 16, a persistent current switch 25 that forms a closed circuit with the main coil 15 and can switch between a normal conductive state and a superconductive state, a first lead 11 and a second lead 12 that are drawn from the non-inductive winding coil 26 of the persistent current switch 25 and connected to the end wires 17, 18 on both sides of the main coil 15, a heat transfer member 45 that supports the main coil 15 and transfers the cold generated by the cryogenic refrigerator 40 to the main coil 15, a support member 20 that has one end connected to the heat transfer member 45 and the other end that supports the persistent current switch 25 and forms the main path of the cold transferred to the persistent current switch 25, and a separation structure that separates the first portion 21 with which the first lead 11 is in electrical contact and the second portion 22 with which the second lead 12 is in electrical contact along the longitudinal direction of the support member 20.

The main coil 15, persistent current switch 25, heat transfer member 45, and support member 20 described above are housed in an insulated vacuum container 28 because they need to be kept below the critical temperature Tc for superconducting transition. This insulating vacuum container 28 further includes a radiation shield 29 in order to reduce the influence of heat intrusion from the environment in which the superconducting electromagnet 10 is installed (room temperature: approximately 300 K). Note that the weight of the radiation shield 29, heat transfer member 45, and persistent current switch 25 is supported from the heat insulating vacuum container 28 by a member not shown.

In the embodiment, a GM refrigerator 40 is illustrated as the cryogenic refrigerator 40. The first freezing stage 41 and the radiation shield 29 of the GM refrigerator 40 are connected, and the second freezing stage 42 and the heat transfer member 45 are connected. The radiation shield 29 is cooled to about 40K and the heat transfer member 45 is cooled to about 4K due to the effect of adiabatic compression of the working gas (He gas, etc.) sealed into the GM refrigerator 40 from a compressor (not shown).

Note that the cryogenic refrigerator 40 employed is not limited to the GM refrigerator described above. Any device that generates extremely low temperatures, such as a pulse tube refrigerator, Claude refrigerator, or Stirling refrigerator, may be used as appropriate.

The heat transfer member 45 is made of a material that has high mechanical rigidity, is not magnetized, and has high thermal conductivity, such as copper, copper alloy, aluminum, or aluminum alloy. The heat transfer member 45 is supported by a support member (not shown) from inside the insulated vacuum vessel 28, and receives cold heat from the abutting cryogenic refrigerator 40. The cold heat supplied from the cryogenic refrigerator 40 is supplied to the main coil 15 and its end wires 17 and 18, which are supported by the heat transfer member 45, and to the electrical connection portion 30. The cold heat supplied from the cryogenic refrigerator 40 is further transmitted to the support member 20 via the heat transfer member 45 and the electrical connection portion 30, and is supplied to the persistent current switch 25.

The support member 20 has its base end fixed to the heat transfer member 45 and the electrical connection part 30, and supports the persistent current switch 25 at its distal end. Further, the support member 20 forms a transition section for the first leader wire 11 and the second leader wire 12 extending from the non-inductively wound coil 26 of the persistent current switch 25 to the electrical connection portion 30. In this way, the support member 20 transfers cold heat from the heat transfer member 45 to the persistent current switch 25, and supports the first leader wire 11 and the second leader wire 12. As the material of the support member 20, copper or aluminum having high thermal conductivity and electrical conductivity at extremely low temperatures may be used, or gold or silver or an alloy containing them may be used.

Note that the weight of the persistent current switch 25 may be entirely borne by the support member 20, or a portion of the weight may be supported by a support member (not shown) extending directly from the heat-insulating vacuum container 28 or the heat transfer member 45. In some cases. Furthermore, the cold heat supplied to the persistent current switch 25 may also be transmitted through another heat transfer member (not shown) extending from the heat transfer member 45, in addition to passing through the support member 20, which is the main path.

Figure 3 is a circuit diagram of the superconducting electromagnet 10 according to the embodiment. In this manner, the superconducting electromagnet 10 has the persistent current switch 25 and the main coil 15 connected in parallel to the excitation power supply 35. By forming a circuit in this manner, the excitation power supply 35 and the main coil 15 form a closed circuit in the driven mode, and the main coil 15 and the persistent current switch 25 form a closed circuit in the persistent current mode (PC mode).

The main coil 15 is constructed by winding a superconducting wire in one direction, and generates an induced magnetic field 16 when a current flows therethrough. The persistent current switch 25 includes two coils in which superconducting wires are wound in opposite directions connected in series, and a non-inductively wound coil 26 that does not generate an induced magnetic field even when current flows. The heat generating section 27 of the persistent current switch 25 includes an electric resistor 37 disposed close to the non-inductive wound coil 26, and a non-inductive wound coil 26 in a superconducting state by controlling the electric power supplied to the electric resistor 37 to generate heat. and a power controller 36 for changing the power to a normal conduction state.

The terminal ends of a pair of end wires 17 and 18 drawn out from the main coil 15 are each connected to an electrical connection part 30. Further, the terminal ends of the pair of first leader wire 11 and second leader wire 12 drawn out from the persistent current switch 25 are also connected to the electrical connection section 30 . In this way, the main coil 15 and persistent current switch 25 are connected in parallel to form a closed circuit.

FIG. 4(A) is a conceptual diagram showing a cross section of the superconducting wire of the main coil 15. Further, FIG. 4(B) is a conceptual diagram showing a cross section of the superconducting wire of the non-inductively wound coil 26 of the persistent current switch 25. In this way, the superconducting wire is composed of a superconductor 46 that switches between a superconducting state and a normal conducting state depending on the set temperature, and a matrix body 47 (47a, 47b) that exhibits a normal conducting state regardless of the set temperature. Although the matrix body 47 and the superconductor 46 are formed in a sea-island shape when viewed in cross section, they are not limited to such a structure, and may be formed, for example, in a layered manner.

FIG. 5 is a graph showing changes in electrical resistance values with respect to temperature of the superconductor 46 and matrix body 47 (47a, 47b) that constitute the superconducting wire. The superconductor 46 has an electrical resistance value of zero at a temperature lower than the critical temperature Tc, and a persistent current can flow therethrough. On the other hand, in the superconductor 46, the electrical resistance value rapidly increases when the critical temperature Tc is exceeded, and the electrical resistance value further increases as the temperature rises. In the embodiment, the NbTi alloy, which is widely used in practical use, is exemplified as the superconductor 46, but the superconductor 46 is not limited thereto.

The matrix body 47a of the main coil 15 is made of an oxygen-free cylinder with a small electrical resistance, and the matrix body 47b of the non-inductive winding coil 26 is made of a copper alloy with a higher electrical resistance than the oxygen-free cylinder. The reason for making the electrical resistance of the matrix body 47b of the non-inductive winding coil 26 large in this way is that it needs to have a sufficiently large electrical resistance in the driven mode in which the persistent current switch 25 is set to OFF (the electrical resistor 37 generates heat), as described below.

Figure 6 is a graph explaining the three critical points of the superconducting state (critical current Ic, critical temperature Tc, critical magnetic field Hc). If any one of these critical points is exceeded, the superconducting wire may transition (quench) from the superconducting state to the normal conducting state and burn out. As can be seen from this graph, even if the temperature of the superconducting wire is lower than the critical temperature Tc, the critical current will decrease from I1 to I2 when the set temperature rises from T1 to T2. For this reason, it is necessary to devise a way to prevent the heat generated by the electrical resistor 37 when the persistent current switch 25 is set to OFF from being transmitted to the leads 11 and 12 as much as possible.

The excitation process of the superconducting electromagnet 10 will be described based on the graph in Figure 7 (see Figure 3 as appropriate). First, the main coil 15 and the persistent current switch 25 are both cooled to temperature T1, which indicates a superconducting state. Next, as shown in Figure 7 (A), the control of the heating unit 27 is enabled to heat the electrical resistor 37, and as shown in Figure 7 (B), the temperature is raised to temperature T3, which indicates a normal conducting state for the non-inductive winding coil 26 of the persistent current switch 25. In the temperature raising process that begins at time t1, at time t2 when the coil temperature exceeds the critical temperature Tc, the persistent current switch 25 is set to OFF, and a closed circuit including the excitation power supply 35 and the main coil 15 is formed.

As shown in FIG. 7(C), the excitation power supply 35 is started at time t2 when the persistent current switch 25 is set to OFF, and the closed circuit of the main coil 15 is turned on so that the excitation current value A1 has a positive slope. Flow an electric current. Then, when this excitation current value A1 reaches the rated value, the current flowing through the closed circuit of the main coil 15 is made constant, and the driven mode is achieved.

After reaching the driven mode, the control of the heat generating section 27 is disabled at time t3 as shown in FIG. 7(A). Then, the temperature of the persistent current switch 25 drops as shown in FIG. 7(B). In the temperature decreasing process starting from time t3, the persistent current switch 25 is set to ON at time t4 when the coil temperature falls below the critical temperature Tc. In addition, it is preferable that the heat transfer from the persistent current switch 25 to the heat transfer member 45 be rapid during this temperature-lowering process, since this will shorten the time difference between time t3 and time t4, and the ON setting of the persistent current switch 25 can be achieved quickly. . Although this requirement is in a trade-off relationship with the above-mentioned requirement to suppress the temperature rise of the lead wires 11 and 12, the design is made with balance in mind.

At time t4 when the persistent current switch 25 returns to the ON setting, a closed circuit between the main coil 15 and the persistent current switch 25 is formed. Then, as shown in FIG. 7(C), the excitation power source 35 is controlled so that the excitation current value A1 has a negative slope. In this process, based on Lenz's law, a persistent current is induced in the closed circuit of the main coil 15 and persistent current switch 25 so as not to change the induced magnetic field 16 passing through the main coil 15, as shown in FIG. 7(D). . The current value A2 of this persistent current increases in inverse proportion to the decrease in the excitation current value A1, and becomes a constant value at the time t5 when the excitation current value A1 becomes zero. At this time t5, a persistent current mode is achieved in which a steady current continues to flow through the main coil 15 without any electromotive force.

Returning to FIG. 2, the explanation will be continued. The electrical connection section 30 includes a first container 31 containing one end wire 17 of the main coil 15 and the first leader wire 11 that have been solidified after being immersed in molten metal, and a first container 31 that accommodates one end wire 17 of the main coil 15 and the first lead wire 11 that have been solidified after being immersed in molten metal, and a first container 31 that accommodates one end wire 17 of the main coil 15 and the first lead wire 11 that have been solidified after being immersed in molten metal, and and a second container 32 that accommodates the second lead wire 12 immersed in molten metal and then solidified. In this way, the electrical connection section 30 electrically connects each of the first leader wire 11 and the second leader wire 12 of the persistent current switch 30 to each of the end wires 17 and 18 of the main coil 15 to form a closed circuit. It is something.

The first container 31 and the second container 32 are made of a metal having excellent electrical conductivity and thermal conductivity, such as copper, aluminum, silver, or the like. As the metal contained in the containers 31 and 32, an alloy having a low melting point and high electrical conductivity, such as solder, is used. Then, the end wires 17 and 18 of the main coil 15 and the first leader wire 11 and the second leader wire 12 are immersed in the first container 31 and the second container 32 in a bundled state so that the specific surface area becomes large, respectively. ing.

Further, an electrical insulator 38 is provided between each of the first container 31 and the second container 32 and the heat transfer member 45 to connect them and conduct heat while ensuring electrical insulation. Further, one end of the first portion 21 of the support member 20 is connected to the heat transfer member 45 via the first container 31 and the electrical insulator 38, and one end of the second portion 22 is connected to the second container 32 and the electrical insulator 38. It is connected to the heat transfer member 45 via.

The interposition of the sheet-shaped electrical insulator 38 makes it possible to maintain electrical insulation while providing thermal contact with low conductance. The electrical insulator 38 may be, for example, a sheet of polyimide, fiber-reinforced plastic, aluminum nitride (AlN), boron nitride, alumina, polyamide (nylon), polyethylene, vinyl chloride, fluororesin, or any of these as components. Examples include materials. In addition to the sheet-like material, the electrical insulator 38 may be made of a material that hardens after being applied to the surface of the heat transfer member 45.

FIG. 8 is a side view of the electrical connection section 30. The holding member 50 includes a contact plate 56 that contacts the first container 31 and the second container 32 via a soft metal 58 serving as a protective material, an upright member 55 provided on the heat transfer member 45, and a contact plate 56 that is pressed against the open end. It has a fixing member 57 that fixes the contact plate 56 to the upright member 55 so as to apply force. Note that this soft metal 58 desirably has a Brinell hardness of 300 MPa or less. By providing such a holding member 50, it is possible to press the first container 31 and the second container 32 in the direction in which the heat transfer member 45 is connected, thereby improving thermal contact between the two.

The electrical insulator 38 is preferably made of a material that has excellent resistance to dielectric breakdown and high thermal conductivity at extremely low temperatures. Specifically, a material such as aluminum nitride (AlN) that has electrical insulation properties and can be processed into a shape with a smooth surface is suitable. Other candidates with such properties include aluminum nitride (AlN), silicon carbide (SiC), sapphire alumina (Al ₂ O ₃ ), quartz (SiO ₂ ), and/or hybrids thereof. . By employing the electrical insulator 38 having such characteristics, the conductivity of cold heat from the heat transfer member 45 is improved, and the temperatures reached by each of the first container 31 and the second container 32 can be lowered. can.

Further, a soft metal 39 is disposed on at least one contact surface of the electrical insulator 38, which is plastically deformed by stress acting in a direction perpendicular to the contact surface and fills the gap. This soft metal 39 desirably has a Brinell hardness of 300 MPa or less. Although FIG. 8 shows an example in which the soft metal 39 is provided on the contact surface with the first container 31 and the second container 32, it may also be provided on the contact surface with the heat transfer member 45.

The soft metal 39 interposed in this manner deforms to follow the fine irregularities on the surfaces of the containers 31 and 32, the electrical insulator 38, and the heat transfer member 45. Thereby, the thermal resistance from the heat transfer member 45 to the electrical connection part 30 is reduced, and the temperatures reached by each of the first container 31 and the second container 32 can be lowered.

Figure 9 (A) is a cross-sectional view of the first lead wire 11 arranged at the first portion 21 of the support member 20 and the second lead wire 12 arranged at the second portion 22. In this way, the first lead wire 11 and the second lead wire 12 are brazed with a metal brazing material 19 such as solder while in contact with the support member 20.

By brazing in this manner, thermal contact and electrical contact between the first leader line 11 or the second leader line 12 and the support member 20 are improved. As a result, even if some instability factor occurs in the lead wires 11 and 12, such as mechanical disturbance or a change in the distribution of the magnetic flux that has entered, the heat generated by these factors is quickly released and the occurrence of quench is suppressed. can. Furthermore, even if the lead wires 11 and 12 partially temporarily transition from the superconducting state to the normal conductive state and signs of quenching appear, the persistent current flowing through the lead wires 11 and 12 is transferred to the support member 20. Can be bypassed. This can prevent progression to quench.

In addition, in FIG. 9(B), a groove 14 is formed in the support member 20 at the position where the first lead wire 11 and the second lead wire 12 contact each other. This groove 14 can further improve the thermal contact and electrical contact between them. To further improve this property, it is desirable for the groove 14 to have an inverted shape of one side of the outer periphery of the lead wires 11 and 12.

FIG. 10(A) is a longitudinal cross-sectional view of a persistent current switch 25 (first example) supported by the support member 20, and FIG. 10(B) is a bottom view thereof. The other end of the support member 20 on which the persistent current switch 25 is supported in this manner is coupled to one flange portion of the bobbin 23 around which the non-inductive winding coil 26 is wound.

FIG. 11(A) is a side view of a persistent current switch 25 (second example) supported by the support member 20, and FIG. 11(B) is a horizontal sectional view thereof. At the other end of the support member 20 on which the persistent current switch 25 is supported, the tip of the first portion 21 is coupled to one flange portion of the bobbin 23, and the tip of the second portion 22 is coupled to the other flange portion of the bobbin 23. It is connected to the flange. Note that the bobbin 23 can be made entirely of an electrical insulator, made of an electrical conductor, or have a flange made of an electrical conductor and a shaft part made of an electrical insulator.

Figure 12 (A) is a side view showing a first example of the support member 20a (20). In this way, the support member 20a may be provided with a narrowed portion 33 in which the cross section perpendicular to the longitudinal direction is reduced. In other words, compared to the part of the support member 20 in thermal contact with the heat transfer member 45 and the part of the support member 20 in thermal contact with the persistent current switch 25, this narrowed portion 33 is a narrow portion in which the cross-sectional area perpendicular to the longitudinal direction is reduced. Note that while the figure shows a state in which the vertical dimension is narrowed, there may also be a state in which the depth dimension is narrowed.

By adjusting the design dimensions of the constriction portion 33 as described above, it is possible to control a portion of the heat generated when the persistent current switch 25 is set to OFF, which is thermally conducted to the heat transfer member 45. In other words, equipment design that suppresses heat conduction in the opposite direction without hindering good heat conduction of cold heat from the heat transfer member 45 to the persistent current switch 25 is facilitated.

FIG. 12(B) is a side view showing a second example of the support member 20b (20). In this way, the support member 20b is formed by arranging two or more types of members 48 and 49 having different thermal conductivities in the longitudinal direction. For example, the first member 48 is made of oxygen-free copper, and the second member 49 is made of a copper alloy such as phosphorus-deoxidized copper. By adjusting the design dimensions of the two or more types of members 48 and 49 constituting the support member 20b (20) in this way, it is possible to obtain the same effect as when introducing the constricted portion 33 in FIG. 12(A). can.

According to the superconducting electromagnet of at least one embodiment described above, the first region in electrical contact with the first leader wire of the persistent current switch and the second region in electrical contact with the second leader wire are separated. Having a separate structure makes it possible to reduce the risk of quenching when cooling by heat conduction.

Although several embodiments of the invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, changes, and combinations can be made without departing from the gist of the invention. These embodiments and their modifications are included within the scope and gist of the invention as well as within the scope of the invention described in the claims and its equivalents.

DESCRIPTION OF SYMBOLS 10... Superconducting electromagnet, 11... First leader wire, 12... Second leader wire, 14... Groove, 15... Main coil, 16... Induction magnetic field, 17, 18... End line, 19... Metal brazing material, 20 (20a, 20b) Support member, 21 First part, 22 Second part, 23 Bobbin, 25 Persistent current switch, 26 Non-inductive coil, 27 Heat generating part, 28 Heat insulating vacuum container, 29 Radiation shield , 30... Electrical connection part, 30... Persistent current switch, 31... First container, 32... Second container, 33... Throttle part, 35... Excitation power source, 36... Power controller, 37... Electrical resistor, 38... Electricity Insulator, 50... Holding member, 56... Contact plate, 57... Fixing member.

Claims (8)

a main coil that generates an induced magnetic field;
a persistent current switch that forms a closed circuit with the main coil and is capable of switching between a normal conducting state and a superconducting state;
a first leader wire and a second leader wire drawn out from the non-inductive winding coil of the persistent current switch and connected to each of the end wires on both sides of the main coil;
a heat transfer member that supports the main coil and transmits cold heat generated by the cryogenic refrigerator to the main coil;
a support member having one end connected to the heat transfer member, supporting the persistent current switch at the other end, and forming a main path for the cold heat transmitted to the persistent current switch;
a separation structure that separates a first part of the support member into which the first leader wire electrically contacts and a second part with which the second leader wire electrically contacts, along the longitudinal direction;
A superconducting electromagnet in which the heat transfer member and the support member are electrically insulated . The superconducting electromagnet according to claim 1,
An electrical connection part that electrically connects the persistent current switch and the main coil to form the closed circuit,
a first container containing the first lead wire and one end wire of the main coil immersed in molten metal and then solidified;
a second container containing the second lead wire and the other end wire of the main coil immersed in molten metal and then solidified;
an electrical insulator that connects each of the first container and the second container to the heat transfer member and conducts heat while ensuring electrical insulation;
one end of the first portion of the support member is connected to the heat transfer member via the first container and the electrical insulator;
One end of the second portion of the support member is a superconducting electromagnet connected to the heat transfer member via the second container and the electrical insulator. The superconducting electromagnet according to claim 2,
A superconducting electromagnet, in which a soft metal is disposed on at least one contact surface of the electrical insulator and is plastically deformed by stress acting in a direction perpendicular to the contact surface to fill a gap. The superconducting electromagnet according to claim 2 or 3,
A superconducting electromagnet in which the opening ends of the first container and the second container are pressed by a holding member in a direction in which the heat transfer member is connected to improve thermal contact. The superconducting electromagnet according to any one of claims 1 to 4,
A superconducting electromagnet, wherein a groove is formed in the support member at a position where the first lead wire and the second lead wire are in contact with each other. The superconducting electromagnet according to any one of claims 1 to 5,
a superconducting electromagnet, the other end of which supports the persistent current switch being coupled to a flange portion of a bobbin around which the non-inductive winding coil of the persistent current switch is wound; The superconducting electromagnet according to any one of claims 1 to 6,
The support member is a superconducting electromagnet having a tapered portion in which a cross section perpendicular to the longitudinal direction is reduced. The superconducting electromagnet according to any one of claims 1 to 6,
The support member is a superconducting electromagnet in which two or more types of members having different thermal conductivities are arranged in the longitudinal direction.

Images