WO1997011472A1

WO1997011472A1 - Superconducting magnet system

Info

Publication number: WO1997011472A1
Application number: PCT/JP1995/001876
Authority: WO
Inventors: Norihide Saho; Takeo Nemoto; Hisashi Isogami; Teruhiro Takizawa
Original assignee: Hitachi, Ltd.
Priority date: 1995-09-20
Filing date: 1995-09-20
Publication date: 1997-03-27
Also published as: JP3107228B2

Abstract

The heat generated from a superconducting switch used for supplying an electric current to a conduction-cooled superconducting magnet system from the outside so as to set the magnet system in a permanent current maintaining mode does not influence the superconducting magnet, because a cooler for cooling the superconducting magnet and a cooler for cooling the superconducting switch are separately provided. Even when one mechanical cooler is used for cooling the superconducting magnet and the switch and it generates different temperature levels, the magnet and switch are thermally coupled to the different temperature-level generating sections of the cooler. Therefore, the superconducting magnet can be maintained stably below the superconduction generating temperature, because the thermal energy for operating the superconducting switch can remarkably reduce the temperature rise at the superconducting magnet cooling part of the cooler.

Description

Specification

Superconducting magnet system

Technical field

The present invention relates to a superconducting magnet system, and more particularly, to a superconducting switch for generating a permanent current for use in a conduction-cooled superconducting magnet operated in a permanent current maintaining mode.

Background art

The conventional superconducting magnet system disclosed in Japanese Patent Publication No. Hei 6—7 3 3 3 4 discloses a superconducting coil that constitutes a superconducting magnet (hereinafter, referred to as a superconducting magnet unless otherwise specified).

An external power supply and a superconducting coil are electrically connected to allow a permanent current to flow through the superconducting coil, and a superconductor connected in parallel to the superconducting coil and a heater for cutting off the superconducting state of the superconductor are provided. A superconducting switch is composed of a conductor and a heater.When current is supplied from an external power supply to the superconducting coil, the superconductor is heated by a heater and the resistance is increased to increase the resistance. It describes a technique in which a coil is electrically connected, and then a heater is turned off to restore the superconducting state of the superconductor and a permanent current is applied to both ends of the superconducting coil and the superconducting switch winding. That is, when the superconducting magnet is cooled below the superconducting generation temperature by the refrigerator, current is supplied from the external power supply to the superconducting coil via the bus, but at this time, the superconducting switch is set to `` 0FF '' The heater of the superconducting switch is heating the superconductor, the temperature of the superconductor rises above the temperature at which superconductivity occurs, and the superconductor is in normal conduction and has an electrical resistance. Therefore, current hardly flows to the superconductor side, but flows to the superconducting magnet having zero electrical resistance, and is supplied at a predetermined current rising speed to a desired current value. After that, the heater of the superconducting switch is turned off, the superconductor is cooled by the cold heat of the refrigerator, the temperature of the superconductor is cooled below the superconducting generation temperature, the superconducting state is established, and the electric resistance is reduced to zero. This Thus, the current flowing through the superconducting magnet is maintained as a permanent current in a closed circuit that connects the superconductors that are also in the superconducting state and the superconductor with zero electrical resistance between the buses. In addition, a quench occurs where the superconductor switches to the normal conduction state for some reason from the permanent current holding operation state where the superconducting switch is `` 0N '', and Joule heat generated by the operating current in the superconductor causes heat damage. Provide sufficient heat capacity to the switch to prevent bleeding.

In this superconducting magnet system, a part of the superconducting magnet is thermally coupled to a cooling station having the lowest temperature of the refrigerator. Then, the superconductor is attached to the inside of the superconducting magnet through a spacer having a small thermal conductivity such as epoxy resin at the same temperature location where the superconducting magnet is cooled, and each cooling station of the expander that cools the superconducting magnet is mounted. It describes cooling the superconductor through a copper bus bar that is thermally connected to the conductor.

When the superconducting switch is in the “0FF” state, the heater of the superconducting switch is heating the superconductor, and the temperature of the superconductor rises above the superconducting generation temperature. For this reason, the heat energy of this heater acts as an extra heat load on the refrigerator that cools the superconducting magnet through the leading bus, and when this exceeds the refrigerating capacity of the refrigerator, the temperature at which the refrigerator can cool increases and the superconducting temperature rises. The superconducting state is destroyed when the temperature of the magnet exceeds the superconducting temperature. In addition, part of the heat of the superconductor that has risen above the temperature at which superconductivity occurs is transmitted directly to the superconducting magnet through the spacer and flows to the cooling station of the refrigerator. For this reason, there is a problem that the temperature of the superconducting magnet in the heat flow path becomes higher than the temperature of the cooling station, and the temperature of the superconducting magnet becomes higher than the superconducting generation temperature, thereby destroying the superconducting state.

Disclosure of the invention

An object of the present invention is to provide a superconducting magnet system equipped with a superconducting switch that does not impose heat load on a cooling refrigerator as much as possible.

The object is to provide a superconducting magnet, a power supply connected to the superconducting magnet and supplying a current, a superconducting switch connected in parallel to the superconducting magnet, In a superconducting system including a conductive magnet and cooling means for cooling the superconducting switch, the cooling means is achieved by means for individually cooling the superconducting magnet and the superconducting switch.

With the configuration of the present invention described above, for example, a refrigerator having a cooling station at a plurality of temperatures, such as a mechanical expander, for example, two temperature levels of 50 K and 5 K. When the same heat load is absorbed by the refrigerator By absorbing the heat load at the higher temperature station, the temperature of the lower station can be maintained at a lower temperature. In other words, since it is an independent cooler with little thermal interference, it is possible to maintain the superconducting magnet at a lower temperature state, thereby preventing quenching. Therefore, with this structure, the heat energy of the heat that turns the superconducting switch on and off can be absorbed by the refrigerator at the cooling stage whose temperature is much higher than the superconducting generation temperature of the superconducting magnet. The heat load of the cooling station is small, and even when the superconducting switch is turned off, the temperature of the superconducting magnet cooled by the low-temperature cooling station does not increase, and the superconducting state of the superconducting magnet is maintained stably. Can be.

The superconducting switch can be turned off by generating a magnetic field that breaks the superconducting state of the superconductor with the superconducting magnet for the switch. At this time, the heat load of the superconducting magnet for the switch can be cooled by the cooling station higher than the superconducting temperature of the superconducting magnet, and the heat load of the cooling station having a lower temperature coupled to the superconducting magnet becomes smaller, and the superconducting magnet becomes smaller. When the switch is turned off, the temperature of the superconducting magnet does not rise and the superconducting state of the superconducting magnet can be maintained.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cross-sectional view illustrating the structure of a superconducting magnet system according to one embodiment of the present invention. FIG. 2 is a diagram illustrating a refrigerator applied to one embodiment of the present invention. FIG. 4 is a cross-sectional view illustrating the structure of a superconducting magnet system according to another embodiment of the present invention, and FIG. 4 is a superconducting magnet system according to another embodiment of the present invention. FIG. 5 is a cross-sectional view illustrating the structure of a superconducting magnet system according to another embodiment of the present invention. FIG. 6 is a cross-sectional view illustrating the structure of a superconducting magnet system according to another embodiment of the present invention. FIG. 7 is a cross-sectional view illustrating the structure of a superconducting magnet system, and FIG. 7 is a cross-sectional view illustrating the structure of a superconducting magnet system according to another embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a vertical cross-sectional view of a vacuum insulation tube in a direction perpendicular to the longitudinal direction. The superconducting magnet 1 is fixed to the bobbin 2 and arranged in the vacuum chamber 3 and is insulated from the room temperature space (outside) by vacuum. The refrigerator 4 is composed of, for example, a Gifford McMahon type expander (hereinafter referred to as a GM expander). The compressor 5 supplies a high-pressure gas helium through a pipe 6 and expands in the refrigerator 4 to expand the first stage. Heat station 8 produces a temperature of about 50 K and second stage heat station 9 produces a temperature of about 5 5. The expanded low-pressure gas helium returns to the compressor 5 through the pipe 7. The bobbin 2 is thermally coupled to the second-stage heat station 9 and, for example, a copper heat conductor 10, and the superconducting magnet 1 further heats through the bobbin 2 and the copper heat conductor 10. And is cooled by the second-stage heat station 9 below the superconducting generation temperature.

The superconducting magnet 1 is connected to an external power supply 11 in a room temperature space and a pair of copper buses 12. The bus bar 12 is connected to a terminal 15 fixed to the flange 13 of the vacuum chamber 3 via an electric insulating material 14. In the vacuum chamber, for example, one end of a copper bus 16 is connected to a terminal 15 and the other end is connected to a copper heat transfer member 17 cooled by a first-stage heat station 8 via an electrical insulating material 18. And fixed to the fixed bus 19. The other end of the bus bar 19 is thermally coupled to a copper heat conductor 20 via an electrical insulator 21, and is cooled by the second-stage heat station 9. The bus 19 and the superconducting magnet 1 are connected by a bus 22 made of superconducting material constituting the superconducting magnet.

To form the superconducting switch 26, the bus 19 is connected by a U-shaped superconductor 23 made of the same material as the bus 19, and the first heat station is used. Heat transfer material fixed to copper heat transfer material 17 cooled by 8 via electrical insulating material 24 (electrically insulating material, but thermally heat transfer material) Is combined with. A part of the superconductor 23 is connected to an electrically insulated heater 27, and the heater 27 is connected to a heater external power supply 28 by a lead wire 29.

In addition, a copper heat shield plate 3a cooled by the first-stage heat station 8 is installed so as to surround the superconducting magnet 1, the busbar 19, and the superconductor 23. It is insulated so that radiant heat from does not enter.

When exciting the superconducting magnet 1 cooled below the superconducting temperature by the refrigerator 1, the superconducting magnet 1 is connected to the superconducting magnet from the external power supply 11 via the bus 12, terminal 15, bus 16 and bus 19 and bus 22. 1 is supplied with current. At this time, the superconducting switch 26 is in the "0FF" state, and the heater 27 of the superconducting switch 26 is receiving current from the external power supply 28 and heating the superconductor 23. . For this reason, the temperature of the superconductor 23 rises above the superconducting generation temperature, and the superconductor shifts to the normal conduction state, and a state where electric resistance is generated. Therefore, due to this electric resistance, current hardly flows to the superconductor side, but flows to the superconducting magnet 1 having the electric resistance as a hole, and is supplied at a predetermined current rising speed to a desired current value.

Then, when the heater 27 of the superconducting switch 26 is turned off, the superconductor 23 is cooled at the first heat station 8 of the refrigerator through the electric insulating material 24 and the copper heat conductor 17. Since the temperature of the superconductor 23 becomes equal to or lower than the superconducting generation temperature, the superconducting state is restored. As a result, the electric resistance of the superconductor 23 becomes zero, and the current flowing through the superconducting magnet 1 becomes the superconductor 2 having the same electric resistance between the bus 19 and the bus 19 in the superconducting state. The inside of the closed circuit electrically connected by 3 is maintained as a permanent current.

In the superconducting magnet system according to the present embodiment, the superconducting magnet 1 is connected to the second stage heater. The superconductor 23 of the superconducting switch 26 is cooled by the first-stage heat station 8. For this reason, the heat load of the heater 27, which is heated when the superconducting switch is in the “0FF” state, is absorbed by the first-stage heat station 8 having a large heat capacity. The temperature rise of 9 is small, and the temperature of superconducting magnet 1 can be maintained at an extremely low temperature. Therefore, even when the superconducting switch is in the “0FF” state, the temperature of the superconducting magnet 1 can be cooled stably below the superconducting generation temperature, and the superconducting state can be maintained.

The reason why the temperature rise of the second-stage heat station 9 can be suppressed in this way will be described with reference to FIG.

Fig. 2 shows a typical Gifford McMaffon expander as a mechanical expander. The same reference numerals as those in FIG. 1 indicate the same components. The expander 4 has a first expansion chamber 41 and a second expansion chamber 92, and these expansion chambers have a two-stage series configuration. The volume of the first expansion chamber 41 having a higher temperature level is larger than that of the second expansion chamber 92 having a lower temperature level. A working fluid at normal temperature and high pressure supplied from the compressor 5 at normal temperature, for example, helium gas, flows through a first cold storage material 43 incorporated in a first disposable laser 42 moving up and down at a predetermined cycle in a first expansion chamber. It flows toward 4 1 and is cooled by the cold energy of the cold storage material. The first cold storage material 43 is made of, for example, a copper wire mesh. A part of the low-temperature and high-pressure helium gas flowing into the first expansion chamber 43 further flows into the second cold storage material 96 built in the second displacer 95 that moves up and down. And is cooled by the cold heat of the cold storage material 96. The second regenerative material 96 is made of, for example, a material filled with spherical particles such as lead and erbium nickel. When the first and second displacers 42, 95 move to the upper end and the expansion volume increases, the supply of high-pressure helium gas is stopped, and both expansion chambers are released to the low-pressure flow path of the compressor. Then, the high-pressure helium gas in these expansion chambers is expanded at a stretch. At this time, the helium gas generates cold and the first heat connected to the expansion chamber. The first stage 8 and the second heat stage 9 are cooled, and the low-temperature and low-pressure heat gas is heated while cooling the heat storage materials 43 and 96 and reaches almost normal temperature and flows into the low-pressure circuit of the compressor 5. I do. At this time, both displacers move to the lower end to minimize the volume of the expansion chamber, exhaust the bleed gas to a low pressure in the expansion chamber, and complete one cycle. In this way, it can be said that the Gifford-Macmaphon expander 4 is composed of two independent expanders.

Since the amount of cold generated in each expansion chamber is substantially determined by the pressure difference between the before and after expansion of the helium gas and the volume of the expansion chamber, the amount of cold generated in the first expansion chamber 41 having a large expansion volume is determined by the second expansion chamber. 5 to 10 times larger than the amount of cold generated in Therefore, when a predetermined amount of heat (in this case, the sum of the amount of heat generated by the heater 27 and the amount of heat generated by the superconductor 23) is cooled by the first heat stage 8, the temperature of the second heat stage 9 rises. In the case where the same amount of heat is cooled by the second heat stage 9, the temperature can be reduced as compared with the temperature rise of the second heat stage 9.

As described above, according to the present embodiment, the superconducting switch 26 is cooled on the high-temperature side (first heat stage 8) of the Gifford / Macmaphon expander 4 composed of two expanders. Therefore, quenching of the superconducting magnet thermally connected to the low-temperature side (second heat stage 9) can be prevented. Incidentally, the reason that the superconductor 23 of the superconducting switch 26 shows a superconducting state at the high temperature side is that the superconductor 23 is made of a bismuth-based high-temperature superconductor.

7 "

In this embodiment, the heat transfer member 17 is made of copper. However, the heat transfer member 17 may be made of Machiyu having a lower thermal conductivity than copper. The material and shape of the electric insulating material 24 and the heat transfer member 17 may be determined so as to be higher than the temperature.

The superconducting magnet constructed in this way is used for nuclear magnetic resonance equipment, and is also used as a plankton, which is the source of aqua and red tide, in water as outlined below. It is also used as a magnetic separation film for separating such as. Utilizing the magnetic field space created by the superconducting magnet 1 in the room temperature bore 3 b inside the vacuum chamber 3, a flow path 3 c is provided inside the room temperature bore 3 b and made of magnetic material in this flow path. A magnetic filter 3d such as a wire mesh is placed. By doing so, a large magnetic gradient is generated on the surface of the magnetic filter 3d by the magnetic field generated by the superconducting magnet 1, so that magnetic particles mixed in the fluid flowing in the flow path can be captured and the fluid can be purified. Such fluids include, for example, sewage containing flocs in which magnetic particles and impurities are integrated with a condensing agent, industrial wastewater containing solid magnetic substances, water flow containing magnetic minerals, gas containing magnetic particles, etc. There is.

Therefore, the present conduction-cooled superconducting magnet system can provide a conduction-cooled superconducting magnet system having a stable superconducting switch that can be used in the conduction-cooled superconducting magnet operated in the permanent current maintaining mode.

FIG. 3 shows another embodiment according to the present invention, which is different from the embodiment shown in FIG. 1 in that a U-shaped superconducting element which is a component of the superconducting switch 26 in FIG. The point is that the body 23 is constituted by a substantially linear superconductor 30. The superconductor 23 is fixed to the heat transfer member 17 via an electric insulating material 27a, a heat transfer control member 27c, and a heater 27b. When the superconductor 23 is made of, for example, a bismuth-based high-temperature superconductor, the conductor is very brittle, so if it is processed into a U-shape, cracks and the like will be generated inside and the superconducting state cannot be stably maintained. Therefore, by forming the superconductor 23 in a linear shape as in the present embodiment, it is possible to provide a conduction-cooled superconducting magnet system having a highly reliable superconducting switch.

FIG. 4 shows another embodiment of the present invention. The difference from the embodiment shown in FIG. 1 is that the configuration of the superconducting magnet 1 and the superconducting switch 26 using two expanders is shown. This is where the superconductors 23 of the element are cooled separately. The superconducting magnet 1 is cooled to a temperature lower than the superconducting temperature at the second heat station 9a (lowest temperature) of the first expander 4a.

Copper heat conductor 17, electrical insulation 18, end of bus 19, superconductor 23, The electrical insulation material 24, the heat transfer material 25, the electrical insulation material 26, the heater 27, and the copper heat shield plate 30 are connected to the first stage heating station 8b (highest temperature) of the expander 4b. After cooling, the other end of bus 19, copper heat conductor 20, electrical insulation 21 and end of bus 22 (these are superconducting at the temperature of the first stage heat station 8b). Is cooled at the second-stage heat station 9b (at substantially the same temperature as the second-stage heat station 9a).

According to this embodiment, compared to the embodiment shown in FIG. 1, the superconducting switch 26 is provided by two cooling devices (expanders 4a and 4b) that are thermally completely independent of the superconducting magnet 1. Since the cooling can be performed individually, the heat that enters the superconducting magnet 1 due to conduction heat conduction through the current lead wire can be cooled by the expander 4b, and the expansion can be performed even when the superconducting switch is in the `` 0FF '' state. This has the effect that the temperature of the superconducting magnet 1 cooled by the machine 4a can be stably cooled below the superconducting generation temperature and the superconducting state can be maintained stably.

In the present embodiment, the supply of helium gas to the expanders 4a and 4b is performed by the compressor 5. The same effect can be obtained even if separate compressors are provided. By arranging, the expander 4a is no longer affected by the heavier gas pressure due to the thermal load fluctuation of the expander 4b, so that the temperature of the superconducting magnet 1 cooled by the expander 4a is lower than the superconducting temperature. This has the effect that the superconducting state can be maintained stably by cooling more stably.

FIG. 5 shows another embodiment according to the present invention. The difference from the embodiment shown in FIG. 4 is that the components of the superconducting magnet 1 and the superconducting switch 26 using two expanders are used. The point is that the superconductors 23 are separately cooled. Thus, the superconducting temperature of superconductor 23 in superconducting switch 26 was set to be higher than the superconducting temperature of superconducting magnet 1 and lower than the superconducting temperature of bus 19. For example, the superconducting magnet 1 is made of a niobium-titanium-based (superconducting state at 4 K) superconductor, the busbar 19 is made of a bismuth-based (superconducting state at 80 K) high-temperature superconducting conductor, and the superconducting switch 2 is manufactured. The superconductor 23 in 6 is made of a niobium-tin-based (superconducting state at 20 K) superconducting conductor Make.

The superconducting magnet 1 is cooled below the superconducting generation temperature at the second-stage heat station 9a of the first expander 4a that generates the lowest temperature. The external power supply 28 and the lead wire 29 for the heater of the superconducting switch shown in FIG. 4, the compressor 5, and the pipes 6 and 7 are not shown. The second superheater switch 26 is cooled by the second heat station 9b of the second expander 4b that generates the next lowest temperature after the second heat station 9a, and the highest temperature is generated. The heat shield plate 30 made of copper is cooled by the first-stage heat station 8b of the second expander 4b. In the first stage 4a of the first expander 4a, the copper heat transfer body 17, electric insulating material 18, the end of the busbar 19, and the copper heat shield plate 30 are cooled by the first-stage heat station 8a. The other end of the bus 19, the copper heat conductor 20, the electrical insulating material 21, and the end of the bus 22a are cooled by the second-stage heat station 9a. The bus bar 2 2b and the superconductor 23 in the superconducting switch 26 are made of the same superconductor, and these are superconductors that become superconductive at the temperature of the first stage heater 9b. It is formed.

According to this embodiment, the heat load of the heater 27 heated when the superconducting switch is in the “0FF” state is absorbed by the second-stage heat station 9 b of the second refrigerator 4 b. Therefore, the influence on the first refrigerator 4a is small, the temperature rise of the second-stage heat station 9a of the first refrigerator 4a is small, and the temperature of the superconducting magnet 1 can be maintained at a very low temperature. Therefore, even when the superconducting switch is in the “0FF” state, there is an effect that the temperature of the superconducting magnet 1 can be stably cooled below the superconducting generation temperature and the superconducting state can be maintained. Also, since the second heat station 9b does not need to be cooled to a temperature of 4 K (the superconductor 23 and the bus 22 of the superconducting switch 26 are composed of a niobium-tin system). It can be cheap.

FIG. 6 shows another embodiment according to the present invention. The difference from the embodiment shown in FIG. 5 is that the components of the superconducting magnet 1 and the superconducting switch 26 using two expanders are used. The superconductors 23 are cooled separately, and the superconductors 23, busbars 19, and busbars 22 are made of bismuth-based high-temperature superconductors. The point is that 23 is cooled by the first stage heating station 8b of the second expander 4b.

Also, the heat shield plate 30 made of copper is cooled by the same first-stage heat station 8b. The second expander has only the first-stage heat station 8b and does not have the second-stage heat station.

According to the present embodiment, the heat load of the heater 27, which is heated when the superconducting switch 26 is in the “0FF” state, is absorbed by the first-stage heat station 8b of the second refrigerator 4b. Therefore, the influence on the first refrigerator 4a is small, and the temperature rise in the second-stage heat station 9a of the first refrigerator 4a, which generates the lowest temperature, is small, and the heat conductor 10a and heat The temperature of the superconducting magnet 1 cooled through the conductive plate 1 Ob can also be maintained at a very low temperature. Therefore, even when the superconducting switch 26 is in the “0FF” state, the temperature of the superconducting magnet 1 can be cooled stably below the superconducting generation temperature and the superconducting state can be maintained. Also, since the second expander 4b has only the first-stage heat station 8b and no second-stage heat station, the compressor of the second expander 4b requires a small processing flow rate, and the compressor can be used. This has the effect of reducing the driving power.

FIG. 7 shows another embodiment of the present invention, which is different from the embodiment shown in FIG. 2 in that means for breaking the superconducting state of the superconductor 23, which is a component of the superconducting switch. The point is that a small superconducting coil 31 made of the same material as the superconductor 23 is used instead of the heater 27. The superconducting coil 31 is molded with an epoxy resin 32 or the like and fixed to the heat transfer member 17 via the heat transfer control member 27c.The superconducting coil 31 is cooled by the first-stage heat station 8. The superconducting state can always be maintained. The superconducting coil 31 for the switch is connected to an external power supply 33 by a bus 34.

When the superconducting switch is set to the “0FF” state, when power is supplied to the superconducting coil 31 from the external power supply 33, a magnetic field crossing the superconductor 23 at right angles is generated, and the superconductor 23 in the magnetic field is generated. The superconducting state breaks down to the normal conducting state, causing electrical resistance. In this case, heat is generated by this electric resistance, but the heater As a result, the temperature fluctuation of the first-stage heat station 8 of the refrigerator 4 is further reduced. For this reason, the temperature rise of the second-stage heat station 9 is further reduced, and the temperature of the superconducting magnet 1 can be maintained at an extremely low temperature, thereby preventing quenching. Therefore, even when the superconducting switch is in the “0FF” state, there is an effect that the temperature of the superconducting magnet 1 can be cooled stably below the superconducting generation temperature and the superconducting state can be maintained. When the superconducting switch is “0N”, the power supply from the external power supply 33 is stopped and the magnetic field generated by the superconducting coil 31 is eliminated. When the magnetic field crossing the superconductor 23 at right angles disappears, the superconductor 23 becomes superconductive again, and a permanent current flows. In the above-described embodiment, a gifford / macmaphon type was described as an example of the mechanical expander. However, the present invention is not limited to this, and is configured by a refrigerator having different low-temperature side and high-temperature side. As long as the method is used, for example, a solver type, a starling type, or a pulse tube type can be applied.

In the above-described embodiment, the case where the superconducting magnet and the superconducting switch are cooled by a refrigerator has been described. However, the superconducting magnet is cooled by a 4.2 K temperature liquid crystal, and the superconducting switch is cooled to a temperature of 77 K. Even when cooling with 4K liquid nitrogen, that is, multiple refrigerants with different temperature levels, it is possible to reduce the consumption of the refrigerant on the lower temperature side, that is, the refrigerant with smaller latent heat, when opening and closing the superconducting switch. There is an effect that the superconducting magnet can be cooled stably.

According to the present invention, since the superconducting switch can be cooled by the cooling station whose superconducting generation temperature is higher than the superconducting generation temperature of the superconducting magnet, the heat load of the lower temperature cooling station coupled to the superconducting magnet is small. Thus, the temperature of the superconducting magnet does not rise when the superconducting switch is turned off, and the superconducting state of the superconducting magnet can be maintained.

The superconducting switch can be turned off by generating a magnetic field that breaks the superconducting state of the superconductor with the superconducting magnet for the switch. At this time, the heat load of the superconducting magnet for the switch can be cooled by a cooling station higher than the superconducting temperature of the superconducting magnet. The heat load of the low cooling station is small, the temperature of the superconducting magnet does not rise when the superconducting switch is turned off, and the superconducting state of the superconducting magnet can be maintained.

Claims

The scope of the claims

1.A superconducting magnet, a power supply connected to the superconducting magnet and supplying a current, a superconducting switch connected in parallel to the superconducting magnet, and cooling means for cooling the superconducting magnet and the superconducting switch. In the superconducting system, the cooling means is a means for individually cooling the superconducting magnet and the superconducting switch.

2.In claim 1, the means for individually cooling is a cooling means having a plurality of cooling levels at a plurality of temperature levels, and a cooling section for cooling the superconducting switch, rather than a cooling section for cooling the superconducting magnet. A superconducting magnet system that cools the cooling temperature with a high cooling unit.

3. The superconducting system according to claim 2, wherein the superconducting switch is made of a substance that becomes superconducting at a higher temperature than the superconducting magnet.

4. The superconducting system according to claim 1, wherein the means for shifting from the superconducting state used for the superconducting switch to the normal conducting state is a heater.

5. The superconducting system according to claim 1, wherein the means for shifting the superconducting state used in the superconducting switch to the normal conducting state is a means for generating a magnetic field.

6. A superconducting magnet, a power supply connected to the superconducting magnet and supplying a current, a superconducting switch connected in parallel to the superconducting magnet, and a cooling means for cooling the superconducting magnet and the superconducting switch. In the superconducting system provided, the cooling means has a plurality of cooling levels, and the first cooling means has a cooling temperature higher than a second cooling part having the lowest cooling temperature of the cooling means. A superconductor that cools a part of the bus that supplies power to the superconducting magnet at the portion, and maintains the bus in a region where the temperature is lower than the first cooling portion at a temperature of the first cooling portion. And the conductor of the superconducting switch is formed of a superconductor that maintains a superconducting state at the temperature of the first cooling portion, and the superconducting switch has a temperature lower than that of the second cooling portion. A superconducting magnet system configured to short-circuit between the buses at a location where the temperature is high.

7. A superconducting magnet, a power supply connected to the superconducting magnet and supplying a current, a superconducting switch connected in parallel to the superconducting magnet, and a cooling means for cooling the superconducting magnet and the superconducting switch. In the superconducting system, the cooling means has a cooling portion having a plurality of temperature levels, and the first cooling portion has a higher cooling temperature than the second cooling portion having the lowest cooling temperature of the cooling means. A part of the bus that supplies power to the superconducting magnet is cooled, and the bus in a region where the temperature is lower than the first cooling part is formed of a superconductor that can maintain a superconducting state at the temperature of the first cooling part. The conductor of the superconducting switch is formed of a superconductor that can maintain a superconducting state at a temperature of a third cooling portion having a lower temperature than the first cooling portion and a higher temperature than the second cooling portion. And, wherein the superconducting Suitsuchi cooled in this third cooling region, the superconducting magnet system configured to short-circuit between the bus bars.