JP7280571B2 - Persistent current switch and superconducting device - Google Patents

Description

The present invention relates to persistent current switches and superconducting devices.

Japanese Patent Laying-Open No. 2004-40036 (Patent Document 1) discloses a persistent current switch. The persistent current switch disclosed in Patent Document 1 is housed in a cooling vessel together with a superconducting coil and cooled by liquid helium.

Japanese Unexamined Patent Application Publication No. 2004-40036

It is an object of one aspect of the present invention to provide a persistent current switch that consumes less power and can operate faster. An object of one aspect of the present invention is to provide a superconducting device including such a persistent current switch.

A persistent current switch according to an aspect of the present invention includes a superconducting wire, a heater, a holding member, a first case, a liquid coolant inlet pipe, a valve, a liquid coolant outlet pipe, and a check valve. A heater is provided on a portion of the superconducting wire. The holding member holds the superconducting wire. The first case is arranged around the holding member with a first space therebetween. The liquid refrigerant inflow pipe communicates with the first space. A valve is provided in the liquid refrigerant inlet pipe. The liquid refrigerant outflow pipe communicates with the first space. A check valve is provided in the liquid refrigerant outflow pipe.

A superconducting device according to one aspect of the present invention includes a persistent current switch according to one aspect of the present invention, and a superconducting coil connected to the persistent current switch.

According to the above, persistent current switches and superconducting devices can operate faster with lower power consumption.

1 is a schematic diagram of a superconducting device according to Embodiments 1 and 2; FIG. 1 is a schematic partial cross-sectional view of a persistent current switch (on state) according to Embodiment 1; FIG. FIG. 3 is a schematic cross-sectional view of the persistent current switch according to Embodiment 1 taken along the cross-sectional line III-III shown in FIG. 2; FIG. 3 is a schematic cross-sectional view of the persistent current switch according to Embodiment 1 taken along the cross-sectional line IV-IV shown in FIG. 2; 1 is a schematic partial cross-sectional view of a persistent current switch (off state) according to Embodiment 1; FIG. 1 is a circuit diagram of a superconducting device according to Embodiment 1. FIG. 1 is a circuit diagram of a superconducting device according to Embodiment 1. FIG. 1 is a circuit diagram of a superconducting device according to Embodiment 1. FIG. 1 is a circuit diagram of a superconducting device according to Embodiment 1. FIG. 1 is a circuit diagram of a superconducting device according to Embodiment 1. FIG. 1 is a circuit diagram of a superconducting device according to Embodiment 1. FIG. FIG. 8 is a schematic partial cross-sectional view of a persistent current switch (on state) according to Embodiment 2; FIG. 8 is a schematic partial cross-sectional view of a persistent current switch (off state) according to Embodiment 2;

[Description of the embodiment of the present invention]
First, embodiments of the present invention will be listed and described.

(1) Persistent current switches 1 and 1b according to one aspect of the present invention include a superconducting wire 10, a heater 16, a holding member 20, a first case 24, a liquid coolant inlet pipe 30, a valve 32, a liquid A refrigerant outflow pipe 34 and a check valve 36 are provided. Heater 16 is provided on a portion of superconducting wire 10 . Holding member 20 holds superconducting wire 10 . The first case 24 is arranged around the holding member 20 with a first space 22 therebetween. The liquid refrigerant inflow pipe 30 communicates with the first space 22 . A valve 32 is provided in the liquid refrigerant inflow pipe 30 . The liquid refrigerant outflow pipe 34 communicates with the first space 22 . A check valve 36 is provided in the liquid refrigerant outflow pipe 34 .

A portion of the superconducting wire 10 is heated by the heater 16 in order to switch the persistent current switches 1, 1b from the ON state to the OFF state. At least a portion of the liquid coolant 3 in the first space 22 is also heated by the heater 16 to become gas 5 . At least part of the first space 22 is filled with gas 5 . The thermal conductivity of gas 5 is lower than that of liquid coolant 3 . Gas 5 reduces the thermal conductivity between first case 24 and heater 16 . The gas 5 suppresses the heat generated by the heater 16 from dissipating to the liquid refrigerant 3 outside the first case 24 . A portion of superconducting wire 10 (superconducting layer 13) included in persistent current switches 1 and 1b transitions from the superconducting state to the normal conducting state with a smaller amount of heat to be heated and in a shorter time. Therefore, the persistent current switches 1, 1b switch from the ON state to the OFF state with lower power consumption and at a higher speed.

In order to switch the persistent current switches 1 , 1 b from the off state to the on state, the valve 32 is opened to allow the liquid coolant 3 to flow into the first space 22 . The liquid coolant 3 that has flowed into the first space 22 absorbs residual heat from the heater 16 . A portion of superconducting wire 10 (superconducting layer 13) transitions to a superconducting state in a short period of time. Therefore, the persistent current switches 1, 1b switch from the off state to the on state at a higher speed. Thus, the persistent current switches 1, 1b consume less power and operate faster.

(2) In the persistent current switches 1 and 1b according to (1) above, part of the superconducting wire 10 and the heater 16 are arranged above the internal space 23 of the first case 24 in the vertical direction. The liquid refrigerant outflow pipe 34 is arranged below the first case 24 in the vertical direction.

The gas 5 generated around the heater 16 moves upward in the vertical direction within the first space 22 . Since part of the superconducting wire 10 and the heater 16 are arranged in the upper part of the inner space 23 of the first case 24 in the vertical direction, the distance for the gas 5 to reach the upper inner surface of the first case 24 is short. Become. By the time the gas 5 reaches the upper inner surface of the first case 24, the possibility of being cooled by the liquid coolant 3 in the first space 22 and returning to the liquid coolant 3 can be reduced. Since the liquid refrigerant outflow pipe 34 is arranged in the lower part of the first case 24 in the vertical direction, when the gas 5 is generated in the first space 22, the liquid in the first space 22 is discharged more than the gas 5. The refrigerant 3 is preferentially discharged from the liquid refrigerant outflow pipe 34 . The gas 5 tends to accumulate in the first space 22 . The gas 5 suppresses the heat generated by the heater 16 from dissipating to the liquid refrigerant 3 outside the first case 24 . Therefore, the persistent current switches 1, 1b switch from the ON state to the OFF state with lower power consumption and at a higher speed.

(3) In the persistent current switch 1, 1b according to (1) or (2) above, the first case 24 is made of resin. In general, resins have a lower thermal conductivity than metals. The first case 24 made of resin prevents the heat generated by the heater 16 from dissipating to the liquid coolant 3 outside the first case 24 . Persistent current switches 1, 1b consume less power and operate faster.

(4) In the persistent current switch 1 or 1b according to any one of (1) to (3) above, the holding member 20 is fixed to the first case 24 using the first resin fixing member 25 . In general, resins have a lower thermal conductivity than metals. The first resin fixing member 25 prevents the heat generated by the heater 16 from dissipating to the liquid coolant 3 outside the first case 24 . Persistent current switches 1, 1b consume less power and operate faster.

(5) In persistent current switch 1 or 1b according to any one of (1) to (4) above, superconducting wire 10 includes superconducting layer 13 . The superconducting layer 13 is made of RE ₁ Ba ₂ Cu ₃ O _y (6.0≦y≦8.0, RE represents a rare earth element). In general, oxide superconducting materials such as RE ₁ Ba ₂ Cu ₃ O _y have higher superconducting transition temperatures than metal superconducting materials such as NbTi. Therefore, the cooling structure and operation control of the persistent current switches 1, 1b can be simplified. Moreover, since the superconducting wire 10 has a large critical current in a high magnetic field, restrictions on the installation positions of the persistent current switches 1 and 1b can be reduced.

(6) In persistent current switches 1 and 1b according to (5) above, superconducting wire 10 further includes protective layer 14 that covers superconducting layer 13 . In a portion of superconducting wire 10 , superconducting layer 13 is exposed from protective layer 14 . Heater 16 is provided on superconducting layer 13 exposed from protective layer 14 . Therefore, when part of the superconducting wire 10 transitions from the superconducting state to the normal conducting state, the current flowing through the superconducting layer 13 continues to flow through the superconducting layer 13 without being bypassed by the protective layer 14.例文帳に追加The heat generated by the heater 16 allows the resistance of the persistent current switches 1, 1b to be higher in a shorter time.

(7) The persistent current switch 1b according to any one of (1) to (6) above further includes a second case 44 . The second case 44 is arranged around the first case 24 with a second space 42 therebetween. The liquid refrigerant inflow pipe 30 and the liquid refrigerant outflow pipe 34 are fluidly separated from the second space 42 . The second space 42 between the first case 24 and the second case 44 prevents the heat generated by the heater 16 from dissipating to the liquid refrigerant 3 outside the second case 44 . Therefore, the persistent current switch 1b switches from the ON state to the OFF state at a lower power consumption and at a higher speed.

(8) In the persistent current switch 1b according to (7) above, the second case 44 is made of resin. In general, resins have a lower thermal conductivity than metals. The second case 44 made of resin prevents the heat generated by the heater 16 from dissipating to the liquid refrigerant 3 outside the second case 44 . The persistent current switch 1b consumes less power and operates faster.

(9) In the persistent current switch 1b according to (7) or (8) above, the second case 44 is fixed to the first case 24 using the second resin fixing member 45 . In general, resins have a lower thermal conductivity than metals. The second resin fixing member 45 prevents the heat generated by the heater 16 from dissipating to the liquid coolant 3 outside the second case 44 . The persistent current switch 1b consumes less power and operates faster.

(10) A superconducting device 50 according to an aspect of the present invention includes persistent current switches 1 and 1b according to any one of (1) to (9) above, a superconducting coil 40, and a container 51. A superconducting coil 40 is connected to the persistent current switches 1 and 1b. A container 51 accommodates the persistent current switches 1 and 1b and the superconducting coil 40 . Therefore, the superconducting device 50 can operate faster with lower power consumption.

[Details of the embodiment of the present invention]
Details of the embodiments will be described below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will not be repeated. You may combine arbitrarily the structure of at least one part of embodiment described below.

(Embodiment 1)
A superconducting device 50 according to Embodiment 1 will be described with reference to FIG. The superconducting device 50 is, for example, a superconducting magnet, a nuclear magnetic resonance (NMR) device, a magnetic resonance imaging (MRI) device, or the like. A superconducting device 50 includes a persistent current switch 1 , a superconducting coil 40 and a container 51 . A superconducting coil 40 is connected in parallel with the persistent current switch 1 . A container 51 accommodates the persistent current switch 1 and the superconducting coil 40 . Vessel 51 is an insulated vessel such as a cryostat. A container 51 contains a liquid coolant 3, such as liquid helium. Liquid coolant 3 cools superconducting coil 40 and persistent current switch 1 .

As shown in FIG. 2, the persistent current switch 1 of Embodiment 1 includes a superconducting wire 10, a heater 16, a holding member 20, a first case 24, a liquid refrigerant inflow pipe 30, a valve 32, It mainly comprises a liquid refrigerant outflow pipe 34 and a check valve 36 .

As shown in FIGS. 3 and 4 , superconducting wire 10 includes substrate 11 , intermediate layer 12 , superconducting layer 13 , and protective layer 14 .

The substrate 11 preferably includes a first layer 11a, a second layer 11b and a third layer 11c. The second layer 11b is formed on the first layer 11a. The third layer 11c is formed on the second layer 11b. The first layer 11a is made of, for example, stainless steel or Hastelloy (registered trademark). The second layer 11b is made of copper (Cu) or a copper alloy, for example. The third layer 11c is made of nickel (Ni). Although substrate 11 is a three-layer substrate in this embodiment, substrate 11 may be a single-layer substrate or a two-layer substrate.

The intermediate layer 12 is formed on the base material 11 (third layer 11c). The intermediate layer 12 is made of an insulating material. _{The intermediate} layer 12 _{is not} particularly limited _. It is composed of at least one selected from the group consisting of lanthanum manganese oxide (LaMnO ₃ ), gadolinium zirconate (Gd ₂ Zr ₂ O ₇ ) and strontium titanate (SrTiO ₃ ).

Superconducting layer 13 is formed on intermediate layer 12 . The superconducting layer 13 is made of, for example, an oxide superconductor. The superconducting layer ₁₃ is _, for example, _RE1Ba2Cu3Oy ( _{6.0≤y≤8.0} ). The rare earth element RE is for example from the group consisting of yttrium (Y), praseodymium (Pr), neodymium (Nd), samarium (Sm), eurobium (Eu), gadolinium (Gd), holmium (Ho) or ytterbium (Yb). At least one element selected.

Protective layer 14 covers superconducting layer 13 . Specifically, protective layer 14 covers the main surface of superconducting layer 13 on the opposite side of substrate 11 . However, superconducting layer 13 is exposed from protective layer 14 in part of superconducting wire 10 . Specifically, in a portion of superconducting wire 10 , the main surface of superconducting layer 13 on the opposite side of substrate 11 is exposed from protective layer 14 . In the longitudinal direction of superconducting wire 10 , protective layer 14 is divided by part of superconducting wire 10 . A portion of superconducting wire 10 is a portion other than both ends of superconducting wire 10 in the longitudinal direction of superconducting wire 10 . The protective layer 14 is made of, for example, a metal such as silver (Ag) or copper (Cu), an alloy, or the like.

As shown in FIGS. 2 and 4, heater 16 is provided on a portion of superconducting wire 10 . The heater 16 is provided, for example, on the superconducting layer 13 exposed from the protective layer 14 . Specifically, the heater 16 is provided on the insulating sheet 17 . The heater 16 is, for example, a meandering heating wire. The heating wire is composed of, for example, a nichrome wire. Insulating sheet 17 may be attached to superconducting wire 10 using an adhesive member (not shown). In a modification of the present embodiment, heater 16 may be a heating wire covered with an insulating film and wound around superconducting wire 10 . A portion of the superconducting wire 10 and the heater 16 are arranged above the internal space 23 of the first case 24 in the vertical direction (z direction). In this specification, the vertical direction (z direction) means the direction of gravity.

As shown in FIG. 2 , holding member 20 holds superconducting wire 10 . Superconducting wire 10 is arranged, for example, in a groove (not shown) provided in holding member 20 . Superconducting wire 10 may be embedded inside holding member 20 . The holding member 20 may be, for example, a winding frame, and the superconducting wire 10 may be wound around the winding frame. The holding member 20 is made of a material with low thermal conductivity. The holding member 20 is made of, for example, fiber reinforced plastic (FRP) such as glass fiber reinforced plastic (GFRP).

The first case 24 is arranged around the holding member 20 with a first space 22 therebetween. The first space 22 is part of the internal space 23 of the first case 24 . The first case 24 is made of resin having low thermal conductivity. The first case 24 is made of, for example, fiber reinforced plastic (FRP) such as glass fiber reinforced plastic (GFRP). The holding member 20 is fixed to the first case 24 using a first resin fixing member 25 . The first resin fixing member 25 is made of, for example, epoxy resin. The first case 24 is provided with a hole through which the superconducting wire 10 passes. The hole is sealed with a first sealing member 26 . The first sealing member 26 is made of resin such as epoxy resin, paraffin resin, or silicone resin.

The liquid refrigerant inflow pipe 30 communicates with the first space 22 . The liquid coolant inflow pipe 30 is arranged above the first case 24 in the vertical direction (z direction). Specifically, the liquid refrigerant inflow pipe 30 is connected to the upper surface of the first case 24 . A valve 32 is provided in the liquid refrigerant inflow pipe 30 . When the valve 32 is in an open state, the valve 32 allows the liquid refrigerant 3 outside the first case 24 to flow into the first space 22 through the liquid refrigerant inlet pipe 30 . When the valve 32 is in the closed state, the valve 32 prevents the liquid refrigerant 3 outside the first case 24 from flowing into the first space 22 through the liquid refrigerant inflow pipe 30 .

The liquid refrigerant outflow pipe 34 communicates with the first space 22 . The liquid refrigerant outflow pipe 34 is arranged below the first case 24 in the vertical direction (z direction). Specifically, the liquid refrigerant outflow pipe 34 is connected to the lower surface of the first case 24 . A check valve 36 is provided in the liquid refrigerant outflow pipe 34 . The check valve 36 prevents the liquid refrigerant 3 outside the first case 24 from flowing into the first space 22 through the liquid refrigerant outflow pipe 34 . The check valve 36 is configured to discharge the liquid refrigerant 3 filled in the first space 22 from the liquid refrigerant outflow pipe 34 when the pressure in the first space 22 exceeds a predetermined pressure. .

The operation of the persistent current switch 1 will be described with reference to FIGS. 2 and 5 to 11. FIG. As shown in FIGS. 6 to 11, persistent current switch 1 is connected in parallel with superconducting coil 40 . Superconducting coil 40 and persistent current switch 1 are connected to current source 39 .

The superconducting coil 40 and the persistent current switch 1 are cooled to a temperature below the superconducting transition temperature. Specifically, as shown in FIG. 2, the superconducting coil 40 and the persistent current switch 1 are immersed in a liquid coolant 3 such as liquid helium. The valve 32 is opened to allow the liquid refrigerant 3 to flow into the first space 22 from the liquid refrigerant inflow pipe 30 . When the first space 22 is filled with the liquid refrigerant 3, the valve 32 is closed. No current flows through the heater 16, and the heater 16 is in an off state. The superconducting layer 13 included in the persistent current switch 1 transitions to a superconducting state and the persistent current switch 1 has zero electrical resistance (ON state of the persistent current switch 1, see FIG. 6). The superconducting coil 40 also transitions to the superconducting state. The current I flowing from the current source 39 is zero.

Then, a current is passed through the heater 16 to turn on the heater 16 (heat generation state). Part of the superconducting wire 10 (superconducting layer 13) transitions to the normal conducting state, and the persistent current switch 1 has an electrical resistance of R (off state of the persistent current switch 1, see FIG. 7). The current I flowing from current source 39 is still zero.

As shown in FIG. 5, when the heater 16 is turned on (heating state), at least part of the liquid coolant 3 (for example, liquid helium) in the first space 22 is heated by the heater 16 to be gaseous. 5 (eg, helium gas). At least part of the first space 22 is filled with the gas 5 from the upper end of the first space 22 toward the lower end of the first space 22 . The thermal conductivity of gas 5 is lower than that of liquid coolant 3 . Gas 5 reduces the thermal conductivity between first case 24 and heater 16 . The gas 5 may insulate the heater 16 from the first case 24 .

Also, the volume of gas 5 is much larger than the volume of liquid refrigerant 3 before it is vaporized into gas 5 . Therefore, the gas 5 increases the pressure inside the first space 22 . When the pressure in the first space 22 exceeds a predetermined pressure, the check valve 36 causes at least part of the liquid refrigerant 3 filled in the first space 22 to be discharged from the liquid refrigerant outflow pipe 34 . The check valve 36 prevents the first case 24 from rupturing when at least part of the liquid coolant 3 in the first space 22 is vaporized into gas 5 .

Then, current I begins to flow from current source 39, as shown in FIG. The current I flowing from the current source 39 is gradually increased from zero by the time change ΔI/Δt of the current I. The superconducting coil 40 has an inductance L. When the current I flowing from the current source 39 is gradually increased, a coil impedance Z is generated in the superconducting coil 40 according to the change ΔI/Δt of the current I over time. An increasing current from zero of the current I flowing from the current source 39 is distributed to the persistent current switch 1 and the superconducting coil 40 according to the electrical resistance R of the persistent current switch 1 and the coil impedance Z of the superconducting coil 40, and the persistent current It flows through switch 1 and superconducting coil 40 . This increased current is given by the time integral ΣΔI/Δt of the time change ΔI/Δt of the current I.

As shown in FIG. 9, when the current I flowing from the current source 39 reaches the operating current _I0 flowing through the superconducting coil 40 in the persistent current mode, the current I flowing from the current source 39 is maintained at the operating current _I0 . The time change ΔI/Δt of the current I flowing from the current source 39 becomes zero, and the coil impedance Z of the superconducting coil 40 also becomes zero. The current flowing through persistent current switch 1 gradually decreases, and the current flowing through superconducting coil 40 gradually increases. The operating current I ₀ flowing from the current source 39 will flow exclusively to the superconducting coil 40 . The superconducting coil 40 is thus excited.

The heater 16 is turned off by stopping the current from flowing through the heater 16 . As shown in FIG. 2 , the valve 32 is opened to allow the liquid refrigerant 3 to flow into the first space 22 from the liquid refrigerant inflow pipe 30 . Gas 5 is discharged through valve 32 or check valve 36 . When the first space 22 is filled with the liquid refrigerant 3, the valve 32 is closed. The liquid coolant 3 that has flowed into the first space 22 absorbs residual heat from the heater 16 . A portion of the superconducting wire 10 (superconducting layer 13) transitions to a superconducting state, and the persistent current switch 1 has zero electrical resistance (ON state of the persistent current switch 1, see FIG. 10).

As shown in FIG. 10, the current I flowing from the current source 39 is gradually decreased from the operating current I ₀ by the time change of the current I -ΔI/Δt. The absolute value of the time increment −ΔI/Δt of current I in FIG. 10 may be equal to or different from the time increment ΔI/Δt of current I in FIG. A reduced current from the operating current I ₀ of the current I flowing from the current source 39 flows through the persistent current switch 1 . This decreasing current is given by the time change of the current I--the time integral of .DELTA.I/.DELTA.t-.SIGMA..DELTA.I/.DELTA.t. As shown in FIG. 11, when the current flowing from current source 39 is made zero, operating current I ₀ circulates through persistent current switch 1 and superconducting coil 40 . Thus, the persistent current switch 1 can operate the superconducting device 50 in persistent current mode.

Effects of the persistent current switch 1 and the superconducting device 50 of this embodiment will be described.

Persistent current switch 1 of the present embodiment includes superconducting wire 10, heater 16, holding member 20, first case 24, liquid coolant inlet pipe 30, valve 32, liquid coolant outlet pipe 34, reverse and a stop valve 36 . Heater 16 is provided on a portion of superconducting wire 10 . Holding member 20 holds superconducting wire 10 . The first case 24 is arranged around the holding member 20 with a first space 22 therebetween. The liquid refrigerant inflow pipe 30 communicates with the first space 22 . A valve 32 is provided in the liquid refrigerant inflow pipe 30 . The liquid refrigerant outflow pipe 34 communicates with the first space 22 . A check valve 36 is provided in the liquid refrigerant outflow pipe 34 .

A portion of the superconducting wire 10 is heated by the heater 16 in order to switch the persistent current switch 1 from the ON state to the OFF state. At least a portion of the liquid coolant 3 in the first space 22 is also heated by the heater 16 to become gas 5 . At least part of the first space 22 is filled with gas 5 . The thermal conductivity of gas 5 is lower than that of liquid coolant 3 . Gas 5 reduces the thermal conductivity between first case 24 and heater 16 . The gas 5 suppresses the heat generated by the heater 16 from dissipating to the liquid refrigerant 3 outside the first case 24 . Part of the superconducting wire 10 (superconducting layer 13) included in the persistent current switch 1 transitions from the superconducting state to the normal conducting state with a smaller amount of heating and in a shorter time. Therefore, the persistent current switch 1 switches from the on state to the off state with lower power consumption and faster. The check valve 36 prevents the first case 24 from rupturing when at least part of the liquid coolant 3 in the first space 22 is vaporized into gas 5 .

In order to switch the persistent current switch 1 from the off state to the on state, the valve 32 is opened allowing the liquid coolant 3 to flow into the first space 22 . The liquid coolant 3 that has flowed into the first space 22 absorbs residual heat from the heater 16 . A portion of superconducting wire 10 (superconducting layer 13) transitions to a superconducting state in a short period of time. Therefore, the persistent current switch 1 switches from the off state to the on state faster. Thus, the persistent current switch 1 consumes less power and operates faster.

In persistent current switch 1 of the present embodiment, part of superconducting wire 10 and heater 16 are arranged above interior space 23 of first case 24 in the vertical direction (z direction). The liquid refrigerant outflow pipe 34 is arranged below the first case 24 in the vertical direction (z direction).

The gas 5 generated around the heater 16 moves upward in the vertical direction (z direction) within the first space 22 . Since part of the superconducting wire 10 and the heater 16 are arranged above the inner space 23 of the first case 24 in the vertical direction (z direction), the gas 5 reaches the upper inner surface of the first case 24 . distance becomes shorter. By the time the gas 5 reaches the upper inner surface of the first case 24, the possibility of being cooled by the liquid coolant 3 in the first space 22 and returning to the liquid coolant 3 can be reduced. Since the liquid refrigerant outflow pipe 34 is arranged below the first case 24 in the vertical direction (z direction), when the gas 5 is generated in the first space 22, the first space 22 The liquid refrigerant 3 inside is preferentially discharged from the liquid refrigerant outflow pipe 34 . The gas 5 tends to accumulate in the first space 22 . The gas 5 suppresses the heat generated by the heater 16 from dissipating to the liquid refrigerant 3 outside the first case 24 . Therefore, the persistent current switch 1 switches from the on state to the off state with lower power consumption and faster.

In the persistent current switch 1 of this embodiment, the first case 24 is made of resin. In general, resins have a lower thermal conductivity than metals. The first case 24 made of resin prevents the heat generated by the heater 16 from dissipating to the liquid coolant 3 outside the first case 24 . The persistent current switch 1 consumes less power and operates faster.

In persistent current switch 1 of the present embodiment, holding member 20 is fixed to first case 24 using first resin fixing member 25 . In general, resins have a lower thermal conductivity than metals. The first resin fixing member 25 prevents the heat generated by the heater 16 from dissipating to the liquid coolant 3 outside the first case 24 . The persistent current switch 1 consumes less power and operates faster.

In persistent current switch 1 of the present embodiment, superconducting wire 10 includes superconducting layer 13 . The superconducting layer 13 is made of RE ₁ Ba ₂ Cu ₃ O _y (6.0≦y≦8.0, RE represents a rare earth element). In general, oxide superconducting materials such as RE ₁ Ba ₂ Cu ₃ O _y have higher superconducting transition temperatures than metal superconducting materials such as NbTi. Therefore, the cooling structure and operation control of the persistent current switch 1 can be simplified. In addition, since the superconducting wire 10 has a large critical current in a high magnetic field, restrictions on the installation position of the persistent current switch 1 can be reduced. The structure of the superconducting device 50 can be simplified and miniaturized.

In persistent current switch 1 of the present embodiment, superconducting wire 10 further includes protective layer 14 covering superconducting layer 13 . In a portion of superconducting wire 10 , superconducting layer 13 is exposed from protective layer 14 . Heater 16 is provided on superconducting layer 13 exposed from protective layer 14 . Therefore, when part of the superconducting wire 10 transitions from the superconducting state to the normal conducting state, the current flowing through the superconducting layer 13 continues to flow through the superconducting layer 13 without being bypassed by the protective layer 14.例文帳に追加The heat generated by the heater 16 allows the resistance of the persistent current switch 1 to be higher in a shorter time. Persistent current switch 1 makes it possible to transfer the current flowing through persistent current switch 1 to superconducting coil 40 in a shorter time.

A superconducting device 50 of this embodiment includes a persistent current switch 1 , a superconducting coil 40 and a container 51 . A superconducting coil 40 is connected to the persistent current switch 1 . A container 51 accommodates the persistent current switch 1 and the superconducting coil 40 . Therefore, the superconducting device 50 can operate faster with lower power consumption.

(Embodiment 2)
A superconducting device 50b of Embodiment 2 will be described with reference to FIG. A superconducting device 50b of the present embodiment has a configuration similar to that of the superconducting device 50 of the first embodiment, but the persistent current switch 1b of the second embodiment is replaced with the persistent current switch 1 of the first embodiment. It has

A persistent current switch 1b according to the second embodiment will be described with reference to FIGS. 12 and 13. FIG. The persistent current switch 1b of the present embodiment has the same configuration as the persistent current switch 1 of the first embodiment, but differs mainly in the following points.

Persistent current switch 1 b further includes a second case 44 . The second case 44 is arranged around the first case 24 with a second space 42 therebetween. The second space 42 is a closed space. At room temperature, the atmosphere of the second space 42 may be an air atmosphere or a reduced-pressure atmosphere such as a vacuum. The second case 44 is made of resin having low thermal conductivity. The second case 44 is made of, for example, fiber reinforced plastic (FRP) such as glass fiber reinforced plastic (GFRP). The second case 44 is fixed to the first case 24 using a second resin fixing member 45 . The second resin fixing member 45 is made of, for example, epoxy resin. A hole through which the superconducting wire 10 penetrates is provided in the second case 44 . The hole is sealed with a second sealing member 46 . The second sealing member 46 is made of resin such as epoxy resin.

The liquid refrigerant inflow pipe 30 and the liquid refrigerant outflow pipe 34 do not communicate with the second space 42 and are fluidly separated from the second space 42 . The liquid refrigerant inflow pipe 30 is arranged above the second case 44 in the vertical direction (z direction). Specifically, the liquid refrigerant inflow pipe 30 is connected to the upper surface of the second case 44 . The liquid refrigerant outflow pipe 34 is arranged below the second case 44 in the vertical direction (z direction). Specifically, the liquid refrigerant outflow pipe 34 is connected to the lower surface of the second case 44 .

Effects of the persistent current switch 1b and the superconducting device 50b of the present embodiment will be described. The persistent current switch 1b of the present embodiment has the following effects in addition to the effects of the persistent current switch 1 of the first embodiment.

Persistent current switch 1 b further includes a second case 44 . The second case 44 is arranged around the first case 24 with a second space 42 therebetween. The liquid refrigerant inflow pipe 30 and the liquid refrigerant outflow pipe 34 are fluidly separated from the second space 42 . The second space 42 between the first case 24 and the second case 44 prevents the heat generated by the heater 16 from dissipating to the liquid refrigerant 3 outside the second case 44 . Therefore, the persistent current switch 1b switches from the ON state to the OFF state at a lower power consumption and at a higher speed.

In the persistent current switch 1b of this embodiment, the second case 44 is made of resin. In general, resins have a lower thermal conductivity than metals. The second case 44 made of resin prevents the heat generated by the heater 16 from dissipating to the liquid refrigerant 3 outside the second case 44 . The persistent current switch 1b consumes less power and operates faster.

In the persistent current switch 1b of the present embodiment, the second case 44 is fixed to the first case 24 using the second resin fixing member 45. As shown in FIG. In general, resins have a lower thermal conductivity than metals. The second resin fixing member 45 prevents the heat generated by the heater 16 from dissipating to the liquid coolant 3 outside the second case 44 . The persistent current switch 1b consumes less power and operates faster.

A superconducting device 50 b of this embodiment includes a persistent current switch 1 b , a superconducting coil 40 and a container 51 . A superconducting coil 40 is connected to the persistent current switch 1b. The container 51 accommodates the persistent current switch 1b and the superconducting coil 40. As shown in FIG. Therefore, the superconducting device 50b can operate at higher speed with lower power consumption.

Embodiments 1 to 3 disclosed this time are illustrative in all respects and should be considered not restrictive. The scope of the present invention is indicated by the scope of the claims rather than the above-described embodiments, and is intended to include meanings equivalent to the scope of the claims and all modifications within the scope.

1, 1b Persistent current switch 3 Liquid refrigerant 5 Gas 10 Superconducting wire 11 Base material 11a First layer 11b Second layer 11c Third layer 12 Intermediate layer 13 Superconducting layer 14 Protective layer 16 Heater 17 Insulating sheet 20 Holding member 22 First space 23 Internal space 24 First case 25 First resin fixing member 26 First sealing member 30 Liquid refrigerant inflow pipe 32 Valve 34 Liquid refrigerant outflow pipe 36 Check valve 39 Current source 40 Superconducting coil 42 Second space 44 Second case 45 Second resin fixing member 46 Second sealing members 50, 50b Superconducting device 51 Container

Claims (10)

a superconducting wire;
a heater provided in a part of the superconducting wire;
a holding member that holds the superconducting wire;
a first case arranged with a first space around the holding member;
a liquid refrigerant inflow pipe communicating with the first space;
a valve provided in the liquid refrigerant inflow pipe;
a liquid refrigerant outflow pipe communicating with the first space;
A check valve provided in the liquid refrigerant outflow pipe,
The part of the superconducting wire and the heater are arranged above the interior space of the first case in the vertical direction,
The persistent current switch, wherein the liquid coolant outflow pipe is arranged below the first case in the vertical direction. a superconducting wire;
a heater provided in a part of the superconducting wire;
a holding member that holds the superconducting wire;
a first case arranged with a first space around the holding member;
a liquid refrigerant inflow pipe communicating with the first space;
a valve provided in the liquid refrigerant inflow pipe;
a liquid refrigerant outflow pipe communicating with the first space;
a check valve provided in the liquid refrigerant outflow pipe ;
A second case arranged around the first case with a second space therebetween,
A persistent current switch , wherein the liquid coolant inflow tube and the liquid coolant outflow tube are fluidly separated from the second space . 3. The persistent current switch according to claim 2, wherein said second case is made of resin . 4. The persistent current switch according to claim 2, wherein said second case is fixed to said first case using a second resin fixing member. The superconducting wire includes a superconducting layer,
5. The superconducting layer according to any one of claims 1 to 4, wherein the _{superconducting} layer is made _{of RE1Ba2Cu3Oy} ( _{6.0≤y≤8.0} , RE represents a rare earth element). A persistent current switch as described. The superconducting wire further includes a protective layer covering the superconducting layer,
In the part of the superconducting wire, the superconducting layer is exposed from the protective layer,
6. The persistent current switch according to claim 5, wherein said heater is provided on said superconducting layer exposed from said protective layer. a superconducting wire;
a heater provided in a part of the superconducting wire;
a holding member that holds the superconducting wire;
a first case arranged with a first space around the holding member;
a liquid refrigerant inflow pipe communicating with the first space;
a valve provided in the liquid refrigerant inflow pipe;
a liquid refrigerant outflow pipe communicating with the first space;
A check valve provided in the liquid refrigerant outflow pipe,
The superconducting wire includes a superconducting layer and a protective layer covering the superconducting layer,
The superconducting layer is RE ₁ Ba ₂ Cu ₃ O. _y (6.0 ≤ y ≤ 8.0, RE represents a rare earth element),
In the part of the superconducting wire, the superconducting layer is exposed from the protective layer,
The persistent current switch, wherein the heater is provided on the superconducting layer exposed from the protective layer. The persistent current switch according to any one of claims 1 to 7, wherein said first case is made of resin . The persistent current switch according to any one of claims 1 to 8, wherein said holding member is fixed to said first case using a first resin fixing member. The persistent current switch according to any one of claims 1 to 9;
a superconducting coil connected to the persistent current switch;
A superconducting device, comprising: a container that houses the persistent current switch and the superconducting coil.

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