JPH0955545A - Current leads for superconducting devices - Google Patents

Abstract

(57) [Summary] [Purpose] It should be possible to operate with a minimal amount of heat penetration without the use of low-temperature helium gas, and it should also be suitable for carrying an alternating current. [Structure] Liquid nitrogen reduced in pressure is supplied from an inlet 21 provided in an outer cylinder 12A of a high temperature side lead 2 having a built-in good conductive conductor 11 to cool the intermediate connection conductor 15 and the good conductive conductor 11. The low temperature side lead 3 is a columnar oxide superconducting conductor 2.
0A and a cylindrical oxide superconducting conductor 2 arranged on the periphery thereof
0B is conductively connected to the intermediate connection conductor 15 and the low temperature terminal 4,
It is housed in the outer cylinder 13 and configured. Further, an oxide superconductor 31 in which a connection conductor 30 for conductively connecting the room temperature terminal 1 of the high temperature side lead 2 and the power supply terminal 51 of the power supply is housed in a heat insulating container.
And the terminal leads 35A and 35B connected thereto, and the reduced pressure liquid nitrogen is supplied from the injection port 36 to cool the oxide superconductor 31 to the superconducting state for use.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting coil device used in a magnetic levitation train, a nuclear fusion device, etc., and a magnetizing current is supplied from an external power source to a superconducting coil housed in a vacuum heat insulation container and immersed in liquid helium. The present invention relates to a current lead for a superconducting device that conducts electricity.

[0002]

2. Description of the Related Art Since a superconducting coil of a superconducting device is used in a superconducting state by being cooled by a cryogenic refrigerant such as liquid helium, it is usually used in a vacuum insulation container equipped with a low-temperature radiation shield and a multilayer insulation layer. It is stored in a state of being immersed in liquid helium.

In order to excite this superconducting coil, it is necessary to incorporate a current lead in the vacuum heat insulation container and connect it to an external power source to supply an exciting current. At this time, since the current lead connects the room temperature part and the cryogenic part, heat enters into the cryogenic side through the current lead, and if this penetration heat is large, a large amount of expensive liquid helium is produced. It will vaporize. Therefore, it is necessary for the current lead to effectively use the low temperature helium gas vaporized by the invasion heat, and the low temperature helium gas vaporized from the cryogenic end is guided to the conductor portion to cool the conductor and cause Joule heat generation. ,
It is customary to remove conduction heat and reduce the heat entering the cryogenic end as much as possible.

It is effective to reduce the cross-sectional area of the conductor of the current lead in order to reduce the invasion heat due to heat conduction from the room temperature portion to the cryogenic portion. However, if the cross-sectional area of the conductor is reduced, the electric resistance increases. The Joule heating increases. Therefore, in consideration of the cooling effect, it is important to select such that the conductor cross-section area and length are well balanced with respect to the current value.

Generally, a metal having good conductivity such as copper or copper alloy is adopted as the conductor of the current lead. However, when an oxide superconductor is discovered and its extremely high critical temperature is effectively utilized. Zero Joule heat generation,
In addition, it is expected that the thermal conductivity will be small, about 1/100 that of copper, and conduction heat can be suppressed. In recent years, development of current leads using oxide superconductors has been advanced.

FIG. 9 is a basic configuration diagram showing a simplified superconducting device incorporating a conventional current lead for a superconducting device. In the figure, a pair of current leads is composed of a high temperature side lead 2 having a room temperature terminal 1 incorporated at one end and a low temperature side lead 3 having a low temperature terminal 4 incorporated at one end, and is connected to a vacuum heat insulating container 7 by a mounting flange 10. ing. A connection conductor 52, which is conductively connected to a power supply terminal 51 of an external power supply 50, is conductively connected to the room temperature terminal 1, and a superconducting body which is housed inside a vacuum heat insulation container 7 and immersed and cooled in liquid helium is connected to the low temperature terminal 4. The coil 5 is conductively connected via the low temperature connection conductor 6. The low-temperature helium gas generated by evaporation of liquid helium due to the invasion heat is introduced into the inside of the low temperature side lead 3 through the He gas inlet 8 installed in the low temperature terminal 4, and further into the inside of the high temperature side lead 2. After being guided and cooled, each conductor is discharged to the outside from a He gas outlet 9 provided in the vicinity of the room temperature terminal 1.

FIG. 10 is a sectional view of the main part of the current lead for the superconducting device shown in FIG. 9, where (a) is a vertical cross section of a part of the high temperature side lead 2 and low temperature side lead 3, and (b) is the high temperature side. The cross section of the lead 2 is shown, and (c) shows the cross section of the low temperature side lead 3. As shown in (b), the high temperature side lead 2 includes a large number of good conductive conductors 11 having a circular cross section and a cylindrical outer cylinder 1.
It is configured by being incorporated into the inside of the 2
Cooling by flowing gas. Copper or a copper alloy is usually used for the good conductive conductor 11.

As shown in (c), the low temperature side lead 3 is constructed by incorporating an oxide superconducting conductor 14 having a circular cross section into an outer cylinder 13, and flowing a low temperature He gas into an internal void. Is cooling. In the oxide superconducting conductor 14,
For example, Bi2223 (Bi ₂ Sr ₂ Ca ₂ Cu, which has a high critical temperature)
₃ O _X ) is used. One end of the oxide superconducting conductor 14 has a large number of good conductive conductors 11 as shown in (a).
Are electrically and mechanically connected to the intermediate connection conductor 15 electrically connected thereto by soldering or the like, and the other end is electrically and mechanically connected to the low temperature terminal 4 by a similar method. The low temperature helium gas generated by the evaporation of liquid helium is introduced into the inside of the low temperature side lead 3 through the He gas inlet 8 installed in the low temperature terminal 4, and cools the oxide superconducting conductor 14 to be in a superconducting state. While being held, it is guided to the inside of the high temperature side lead 2 through the gas flow hole 16 provided in the intermediate connection conductor 15, and the good conductive conductor 1
1 is cooling.

FIG. 11 is a configuration diagram of a connecting portion between the room temperature terminal 1 and the power source terminal 51 of the power source 50 in FIG. 9, (a) is a plan view, and (b) is a side view. Room temperature terminal 1 and power supply terminal 51
Are connected by a connecting conductor 52 made of a highly conductive metal, and are electrically and mechanically connected and coupled by a bolt 54.

[0010]

The conventional current lead for a superconducting device is configured as described above to suppress the heat entering the cryogenic portion and reduce the consumption of liquid helium. However, even in the current lead for the superconducting device configured as described above, (1) low-temperature helium gas is used to cool each conductor of the low-temperature side lead 3 and the high-temperature side lead 2, so that expensive liquid helium Use is essentially unavoidable.

(2) Further, the room temperature terminal 1 arranged in the atmosphere
Since the connecting conductor 52 connected to this and the connecting conductor 52 are not provided with a special cooling device, the temperature rises due to Joule heat generation due to energization. Therefore, the temperature at the room temperature end of the high temperature side lead 2 becomes high, and the heat entering from the room temperature part to the cryogenic part increases. As a result, the amount of evaporation of expensive liquid helium increases.

(3) Furthermore, in the structure of the low temperature side lead 3 constructed by incorporating the oxide superconducting conductor 14 having a circular cross section into the outer cylinder 13, when an alternating current is applied,
Due to the skin effect, a current flows only in the outer peripheral portion, so that the current-carrying capacity is significantly reduced as compared with the DC current-carrying. There were some difficulties.

The present invention has been made in view of the above circumstances, and an object thereof is to provide (1) a current lead for a superconducting device which can be cooled without using expensive liquid helium. (2) Further, the current lead for a superconducting device is provided in which the temperature rise of the room temperature terminal 1 is suppressed, the heat entering from the room temperature section to the cryogenic section is reduced, and the evaporation amount of liquid helium is reduced.

(3) Further, the present invention provides a current lead for a superconducting device, which has a sufficient current-carrying capacity even when an alternating current is applied. It is in.

[0015]

In order to achieve the above-mentioned object, in the present invention, a superconducting device for supplying an exciting current from an external power source to a superconducting coil housed in a vacuum heat insulation container and immersed in liquid helium. In the current lead,
A part of the attached conductor is a conductor cooled with decompressed liquid nitrogen.

Further, there is provided a current lead for a superconducting device, wherein a good conductive conductor contained in a high temperature side current lead and an oxide superconducting conductor contained in a low temperature side lead are conductively connected in series through an intermediate connecting conductor. , The intermediate connection conductor and the good conductive conductor are cooled with decompressed liquid nitrogen.
Furthermore, the connection conductor connecting the room temperature terminal provided at the room temperature end of the current lead for the superconducting device and the power supply terminal of the external power supply is placed in a heat insulating container and cooled with decompressed liquid nitrogen.

Further, a connection conductor for connecting the above-mentioned normal temperature terminal and the power supply terminal of the external power supply is formed by using one or a plurality of oxide superconductors connected in parallel, and cooled by decompressed liquid nitrogen. I decided to. Furthermore, a pair of connecting conductors connected to the room temperature terminals of a pair of current leads for superconducting devices connected to the same superconducting coil are placed in the same heat insulating container and cooled by decompressed liquid nitrogen. .

Further, in the above-mentioned heat insulating container for connecting conductors, which comprises a liquid nitrogen container for storing decompressed liquid nitrogen and a vacuum container arranged outside thereof, at least one of the liquid nitrogen container and the vacuum container is provided. The liquid nitrogen container is made of an electrically insulating material. In addition, it is a current lead for superconducting devices that energizes an exciting current from an external power source to a superconducting coil that is housed in a vacuum insulation container and immersed in liquid helium. In a current lead for a superconducting device in which oxide superconducting conductors are conductively connected in series via an intermediate connecting conductor, the oxide superconducting conductor is a cylindrical conductor or a cylindrical conductor and a cylinder coaxially arranged around the conductor. It shall consist of a parallel connection with the conductor.

Further, in a current lead for a superconducting device for supplying an exciting current from an external power source to a superconducting coil housed in a vacuum heat insulation container and immersed in liquid helium, a good conductive conductor and a low temperature side incorporated in the high temperature side current lead. In a current lead for a superconducting device in which an oxide superconducting conductor contained in a lead is conductively connected in series through an intermediate connecting conductor, a plurality of oxide superconducting conductors are arranged in a cylindrical conductor or a cylindrical conductor and an outer periphery thereof. And the coaxial cylindrical conductor of (1) are connected in series with each other with a gap provided therebetween and are folded and connected in the radial direction.

Further, in a current lead for a superconducting device for supplying an exciting current from an external power source to a superconducting coil housed in a vacuum heat insulation container and immersed in liquid helium, a good conductive conductor and a low temperature side incorporated in a high temperature side current lead. In a current lead for a superconducting device in which an oxide superconducting conductor contained in a lead is conductively connected in series via an intermediate connecting conductor, an intermediate portion in which both ends of the oxide superconducting conductor are conductively connected to an outer peripheral portion of the oxide superconducting conductor. The outer cylinder connected to the connection conductor and the low temperature terminal is composed of a series connection body in which a plurality of coaxial cylindrical members are radially folded and connected to each other with a gap therebetween.

[0021]

[Function] The boiling point of liquid nitrogen is about 77K at atmospheric pressure, but when it is decompressed, the boiling point decreases to about 65K at about 100 Torr.
K, that is, a low temperature of about −208 ° C. Therefore, if a part of the conductor attached to the current lead for the superconducting device is cooled by using the reduced pressure liquid nitrogen, it is possible to obtain the current lead for the superconducting device with low heat loss without cooling with expensive helium. .

In particular, the critical current value, which is the allowable current-carrying limit of the oxide superconducting conductor in the superconducting state, increases as the temperature decreases. For example, in an oxide superconducting conductor such as a bismuth oxide superconducting conductor, the temperature is about 65K. The critical current value at that time is more than twice the critical current value at about 77K. Therefore, in the current lead for the superconducting device in which the good conductive conductor built in the high temperature side current lead and the oxide superconducting conductor built in the low temperature side lead are conductively connected in series through the intermediate connecting conductor, the intermediate connecting Conductor and good conductive conductor,
When cooled with the reduced pressure liquid nitrogen, the oxide superconducting conductor having the high temperature end connected to the intermediate connecting conductor is kept at a temperature equal to or lower than the pressure of the reduced pressure liquid nitrogen unless Joule heat is generated in the superconducting state. Therefore, the oxide superconducting conductor can be maintained in a superconducting state without using an expensive low-temperature helium gas for cooling as in the conventional case, and the amount of heat penetrating into the low-temperature end can be made small to cool the superconducting coil. The amount of liquid helium vaporized can be suppressed to a very small amount.

Furthermore, if a connection conductor for connecting the room temperature terminal provided at the room temperature end of the current lead for the superconducting device and the power supply terminal of the external power supply is placed in the heat insulating container and cooled by the decompressed liquid nitrogen, Since both ends of the room temperature terminal are cooled by the cooled conductor inside the current lead and the connection conductor cooled by depressurized liquid nitrogen, the temperature rise during energization is suppressed, and as a result, the temperature rise to the low temperature part is suppressed. Invasion heat is reduced.

In particular, if the connecting conductor is formed of an oxide superconductor, Joule heat generation in the connecting conductor is eliminated, so that the temperature rise of the room temperature terminal is effectively suppressed and the heat entering the low temperature portion is prevented. It is especially effective for reduction. Further, in the case of passing an alternating current, the current flows only on the surface of the conductor due to the skin effect, so if the connecting conductor is formed using a plurality of oxide superconductors connected in parallel, the surface area ratio is Since the size increases relatively, the required cross-sectional size is reduced and the size is reduced.

Furthermore, a pair of connecting conductors connected to the room temperature terminals of a pair of superconducting device current leads connected to the same superconducting coil are placed in the same adiabatic container and cooled with decompressed liquid nitrogen. For example, a compact and lightweight adiabatic cooling device can be used for effective cooling. Further, in the heat insulating container for the connecting conductor, which comprises a liquid nitrogen container for storing decompressed liquid nitrogen and a vacuum container arranged outside thereof, the liquid nitrogen container is formed of an electrically insulating material. If so, even when an AC current is applied to the connecting conductor and the heat insulating container is exposed to an AC magnetic field, the eddy current loss that occurs in the liquid nitrogen container can be suppressed to an extremely small amount, so that it is supplied to the liquid nitrogen container. It is possible to suppress an increase in heat load on the decompressed liquid nitrogen. If the vacuum container is made of an electrically insulating material in addition to the liquid nitrogen container, the temperature rise due to the eddy current loss of the vacuum container is suppressed, so the heat from the vacuum container to the liquid nitrogen container is reduced. The increase in the invasion amount can also be suppressed.

Further, in a current lead for a superconducting device in which a good conductive conductor of a high temperature side current lead and an oxide superconducting conductor of a low temperature side lead are conductively connected in series through an intermediate connecting conductor, the oxide superconducting conductor is If it is composed of a parallel connection body of a cylindrical conductor or a cylindrical conductor and a cylindrical conductor coaxially arranged on the outer periphery of the conductor, it flows to the outermost outer cylindrical conductor when an AC current is applied, As a result, the current-carrying capacity when an alternating current is applied greatly increases.

Further, in a current lead for a superconducting device in which a good conductive conductor of a high temperature side current lead and an oxide superconducting conductor of a low temperature side lead are conductively connected in series via an intermediate connecting conductor, the oxide superconducting conductor is If a columnar conductor or a cylindrical conductor and a plurality of coaxial cylindrical conductors arranged on the outer periphery of the conductor are connected in series by being folded and connected in the radial direction with a gap therebetween, an intermediate connection conductor is obtained. Since the connection length of the conductor portion with the low temperature terminal is increased, the thermal resistance is increased and the invasion heat is reduced.

Further, in the current lead for a superconducting device in which the good conductive conductor of the high temperature side current lead and the oxide superconducting conductor of the low temperature side lead are conductively connected in series through the intermediate connecting conductor, the outer periphery of the oxide superconducting conductor In the part, an intermediate connecting conductor to which both ends of the oxide superconducting conductor are conductively connected and an outer cylinder arranged to be connected to the low temperature terminal are connected by folding a plurality of coaxial cylindrical members in the radial direction with a gap between them. In the case of using the above-mentioned series connection body, the connection length of the supporting member between the intermediate connection conductor and the low temperature terminal is increased, so that the thermal resistance is increased and the penetration heat is reduced.

[0029]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first current lead for a superconducting device of the present invention.
FIG. 3 is a basic configuration diagram showing the embodiment of FIG. 3B, showing a current conductor including a high temperature side lead and a low temperature side lead, and a connection conductor connected between a power source. Components having the same functions as those of the conventional example are designated by the same reference numerals, and the description thereof will be omitted.

The first difference between this embodiment and the conventional example is that in the conventional example, each conductor was cooled by low-temperature helium gas, whereas in this embodiment, the intermediate connecting conductor 15 and the high temperature were used. The good conductive conductor 11 housed in the side lead 2 is
The point is that it is cooled by the decompressed liquid nitrogen supplied from the inlet 21 provided at the lower end of the outer cylinder 12A and discharged from the outlet 22 provided at the upper end. In this configuration, the intermediate connecting conductor 15 is cooled by the depressurized liquid nitrogen, and the oxide superconducting conductor 2 located on the lower temperature side than that is cooled.
Since 0A and 20B are cooled to a temperature sufficiently lower than the critical temperature, they will be maintained in the superconducting state without flowing low-temperature helium gas.

The second difference lies in the connection conductor for conductively connecting the room temperature terminal 1 installed on the upper end of the high temperature side lead 2 and the power supply terminal 51. In the conventional example, the connection conductor 52 is placed in the atmosphere.
In contrast to this, in the present embodiment, the connection conductor 30 of the system in which the columnar oxide superconductor 31 is cooled by the decompressed liquid nitrogen is used. Connection conductor 3 of this method
0 is a columnar oxide superconductor 31 as shown in the longitudinal sectional view in FIG. 2 and the transverse sectional view taken along the line AA in FIG.
Is supported and stored by a space piece 38 inside a metallic liquid nitrogen container 34 housed in a metallic vacuum container 33 for heat insulation. At both ends of the oxide superconductor 31, the insulating tube 3 is provided.
Liquid nitrogen container 34 and vacuum container 3 by 2A and 32B
3 and the electrically insulated terminal leads 35A and 35B are connected to and guided to the atmosphere, and electrically connected to the room temperature terminal 1 and the power supply terminal 51, respectively. The liquid nitrogen used for cooling the oxide superconductor 31 is decompressed by a decompression device 41 connected to a liquid nitrogen tank 40 via a valve 42, supplied from a filling port 36 to a liquid nitrogen container 34 by a pump 43, and discharged. It is configured to be discharged from the outlet 37 to the outside. In this configuration, since the oxide superconductor 31 is cooled by the decompressed liquid nitrogen and kept in the superconducting state, and Joule heat is completely eliminated, the temperature of the room temperature terminal 1 is suppressed to a low level, and the current lead for the superconducting device penetrates. Heat is reduced. As the material used for the oxide superconductor 31, any of a bismuth-based oxide superconductor, a yttrium-based oxide superconductor, and a thallium-based oxide superconductor may be used. Further, although the oxide superconductor 31 of the embodiment is shown as a single columnar oxide superconductor, the shape is not limited to the columnar shape, and it may be a cylindrical columnar shape, a polygonal columnar shape, or a hollow polygonal shape. It may have a columnar shape or the like, and may be configured as a plurality of parallel connection bodies instead of only one. Furthermore, the oxide superconductor 31 is not limited to one made of only an oxide superconducting material, but a reinforcing material for imparting mechanical strength and a stabilizing material for imparting thermal or electrical stability. It may be configured additionally.

The third difference is that the conductor incorporated in the low temperature side lead 3 is a columnar oxide superconducting conductor 14 in the conventional example.
In contrast to this, the present embodiment is configured as a parallel connection body of the columnar oxide superconducting conductor 20A and the thin cylindrical oxide superconducting conductor 20B arranged on the outer periphery thereof. In this configuration, when a direct current is applied, a columnar oxide superconducting conductor 20A having a large cross section is provided.
Although a majority of the current flows through the outer surface of the cylindrical oxide superconducting conductor 20B, when an alternating current is applied, it flows in the outer layer of the cylindrical oxide superconducting conductor 20B, which is the outermost layer. Since the length is significantly increased, the current carrying capacity of the alternating current is significantly increased.

FIG. 4 is a cross-sectional view of the connecting conductor of the second embodiment of the current lead for the superconducting device of the present invention. Another embodiment of the connecting conductor of the system in which the oxide superconductor is cooled by decompressed liquid nitrogen is shown. This is an example. Connection conductor 30A of this embodiment
In FIG. 2, two oxide superconductors 31A and 31B are housed inside the liquid nitrogen container 34, respectively connected to two terminal leads (not shown) that are electrically insulated from each other, and are guided to the atmosphere. Is configured as
It is used by conductively connecting to two room temperature terminals of a pair of current leads connected to the superconducting coil. In this configuration, since the pair of connecting conductors are housed inside the single liquid nitrogen container 34, the temperature of the room temperature terminal 1 can be kept low and the intrusion heat of the current lead for the superconducting device can be suppressed with a compact and lightweight configuration. Can be reduced. The oxide superconductors 31A and 31A
Similar to the oxide superconductor 31 shown in FIG. 3 described above, B can be formed by selecting from the above-mentioned various materials, shapes and configurations.

FIG. 5 is a longitudinal sectional view of a connecting conductor of a third embodiment of the current lead for a superconducting device of the present invention. Differences between the connection conductor 30 of the first embodiment shown in connection conductors 30B and FIG. 2 of the present embodiment is in the material forming the container for storing the oxide superconductor 31, the vacuum container of the present embodiment Both 33 and the liquid nitrogen container 34 are formed by using a fiber reinforced resin (FRP) which is an electrically insulating material. Therefore, even when an alternating current is applied, the vacuum container 33
Also, since the eddy current loss in the liquid nitrogen container 34 is suppressed to a small extent, an increase in the heat load on the reduced pressure liquid nitrogen supplied for cooling the oxide superconductor 31 is suppressed to a slight extent.

FIG. 6 is a basic block diagram of a low temperature side lead according to a fourth embodiment of the current lead for a superconducting device of the present invention.
(A) is a vertical cross-sectional view of the high temperature side lead and the low temperature side lead,
(B) is a cross-sectional view of the low temperature side lead. In this configuration,
Two cylindrical oxide superconducting conductors 20C and 20D in which conductors made of an oxide superconductor are concentrically arranged.
It is composed of a parallel connection body. Also in this embodiment, as in the case of the first embodiment shown in FIG. 1, it is possible to greatly increase the current carrying capacity when an alternating current is applied.

FIG. 7 is a basic block diagram of a low temperature side lead according to a fifth embodiment of the current lead for a superconducting device of the present invention.
(A) is a vertical cross-sectional view of the high temperature side lead and the low temperature side lead,
(B) is a cross-sectional view of the low temperature side lead in the BB cross section of (a). In this configuration, the conductor made of the oxide superconductor is made of the oxide superconductor 20E formed as a series connection body in which a plurality of coaxial cylindrical conductors are folded and connected in the radial direction with a gap therebetween. In this configuration, since the effective length of the conductor connecting the intermediate connection conductor 15 and the low temperature terminal 4 becomes long, the thermal resistance becomes high, and the heat entering through the conductor can be effectively reduced.

FIG. 8 is a basic configuration diagram of a low temperature side lead according to a sixth embodiment of the current lead for a superconducting device of the present invention.
(A) is a vertical cross-sectional view of the high temperature side lead and the low temperature side lead,
(B) is a cross-sectional view of the low temperature side lead in the BB cross section of (a). In this configuration, the outer cylinder 13A made of stainless steel that supports the oxide superconducting conductor 14 is formed as a series connection body in which a plurality of coaxial cylinders are folded and connected in the radial direction with a gap between each other. Since the effective length connecting the low temperature terminal 15 and the low temperature terminal 4 becomes long, the heat entering through the support can be effectively reduced.

In the current lead for the superconducting device of the first embodiment shown in FIG. 1, as described above, the high temperature side lead is cooled with the reduced pressure liquid nitrogen, and the reduced pressure liquid of the connecting conductor connected to the room temperature terminal is used. At the same time, three points were adopted: cooling with nitrogen, and introduction of a cylindrical oxide superconducting conductor into the conductor built in the low temperature side lead.
Alternatively, it goes without saying that even the current leads for superconducting devices incorporating two points are effective for reducing intrusion heat, conducting alternating current, and the like.

[0039]

As described above, according to the present invention, in the current lead for the superconducting device for supplying the exciting current from the external power source to the superconducting coil housed in the vacuum heat insulating container and immersed in the liquid helium, Since we decided to use a part of the conductor to be cooled with decompressed liquid nitrogen, the conductor is effectively cooled and removed, and the evaporation amount of liquid helium is small without using expensive low-temperature helium gas. It is now possible to obtain a current lead for use.

Further, in a current lead for a superconducting device, a good conductive conductor built in a high temperature side current lead and an oxide superconducting conductor built in a low temperature side lead are conductively connected in series through an intermediate connecting conductor. , If the intermediate connection conductor and the good conductive conductor are cooled with depressurized liquid nitrogen,
The oxide superconducting conductor built in the low temperature side lead can be kept in a superconducting state to eliminate Joule heat generation, and the evaporation amount of liquid helium that cools the superconducting coil is very small even without using expensive low temperature helium gas. It is possible to obtain a current lead for a superconducting device.

Further, if a connection conductor for connecting the room temperature terminal provided at the room temperature end of the current lead for the superconducting device and the power supply terminal of the external power supply is arranged in a heat insulating container and cooled by decompressed liquid nitrogen. Since the Joule's calorific value of the connection conductor is reduced and the heat is removed, the temperature rise at the room temperature end is suppressed, and the current lead for the superconducting device in which the amount of heat entering the low temperature part is reduced can be obtained.

Furthermore, if the above-mentioned connecting conductor is formed by using an oxide superconductor, Joule heat generation in the connecting conductor is eliminated, so that the temperature rise at the room temperature end is effectively suppressed and the low temperature portion is suppressed. The amount of heat penetrating into the superconducting device becomes small, and the current lead for the superconducting device in which the evaporation amount of liquid helium is reduced can be obtained. Further, by forming a plurality of oxide superconductors connected in parallel, a miniaturized current lead for a superconducting device for alternating current can be obtained.

Furthermore, a pair of connecting conductors connected to the room temperature terminals of a pair of current leads for superconducting devices connected to the same superconducting coil are placed in the same heat insulating container and cooled with decompressed liquid nitrogen. In this case, a current lead for a superconducting device, which has a small amount of intruding heat and is effectively cooled by a small and lightweight adiabatic cooling device, can be obtained. further,
In a case where the heat insulating container of the connection conductor comprises a liquid nitrogen container for storing decompressed liquid nitrogen and a vacuum container arranged outside thereof, at least the liquid nitrogen container and the vacuum container are electrically insulated. If it is made of a conductive material, the eddy current loss of the container during energization of an alternating current is suppressed, so that a current lead for a superconducting device for energizing an alternating current with a low heat penetration amount can be obtained.

Further, in a current lead for a superconducting device in which a good conductive conductor of a high temperature side current lead and an oxide superconducting conductor of a low temperature side lead are conductively connected in series through an intermediate connecting conductor, the oxide superconducting conductor is If it is composed of a parallel connection of a cylindrical conductor or a cylindrical conductor and a cylindrical conductor arranged coaxially on the outer periphery of the conductor, it will flow to the outermost cylindrical conductor with a large diameter when an AC current is applied. Therefore, it is possible to obtain a current lead for a superconducting device in which the current-carrying capacity of an alternating current is significantly improved as compared with the conventional one.

Further, in a current lead for a superconducting device in which a good conductive conductor of a high temperature side current lead and an oxide superconducting conductor of a low temperature side lead are conductively connected in series through an intermediate connecting conductor, the oxide superconducting conductor is If a columnar conductor or a cylindrical conductor and a plurality of coaxial cylindrical conductors arranged on the outer periphery of the conductor are connected in series by fold-folding them in the radial direction with a gap between them, an intermediate connecting conductor Since the effective length between the low temperature terminal and the thermal resistance is increased, the current lead for the superconducting device in which the intrusion heat is reduced can be obtained.

Further, in the current lead for a superconducting device in which the good conductive conductor of the high temperature side current lead and the oxide superconducting conductor of the low temperature side lead are conductively connected in series through the intermediate connecting conductor, the outer periphery of the oxide superconducting conductor is In the part, an intermediate connecting conductor to which both ends of the oxide superconducting conductor are conductively connected and an outer cylinder arranged to be connected to the low temperature terminal are connected by folding a plurality of coaxial cylindrical members in the radial direction with a gap between them. If it is made up of a series connected body, the effective thermal length of the supporting member between the intermediate connection conductor and the low temperature terminal is increased, and the thermal resistance is increased. Leads will be obtained.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of a first embodiment of a current lead for a superconducting device of the present invention.

FIG. 2 is a vertical sectional view of a connection conductor of a first embodiment of the current lead for a superconducting device of the present invention shown in FIG.

FIG. 3 is a transverse cross-sectional view of the connection conductor of the first embodiment of the current lead for the superconducting device of the present invention shown in FIG.

FIG. 4 is a cross-sectional view of a connection conductor of a second embodiment of a current lead for a superconducting device of the present invention.

FIG. 5 is a vertical sectional view of a connecting conductor of a third embodiment of a current lead for a superconducting device of the present invention.

FIG. 6 is a basic configuration diagram of a low temperature side lead of a fourth embodiment of a current lead for a superconducting device of the present invention, (a) is a vertical sectional view of a high temperature side lead and a low temperature side lead, and (b) is a low temperature side. Lead cross section

FIG. 7 is a basic configuration diagram of a low temperature side lead of a fifth embodiment of a current lead for a superconducting device of the present invention, (a) is a vertical sectional view of a high temperature side lead and a low temperature side lead, and (b) is a low temperature side. Lead cross section

FIG. 8 is a basic configuration diagram of a low temperature side lead of a sixth embodiment of a current lead for a superconducting device of the present invention, (a) is a vertical sectional view of a high temperature side lead and a low temperature side lead, and (b) is a low temperature side. Lead cross section

FIG. 9 is a basic configuration diagram showing a simplified superconducting device incorporating a conventional current lead for a superconducting device.

FIG. 10 is a cross-sectional view of a main part of the conventional current lead for a superconducting device shown in FIG. 9, where (a) is a vertical cross section of a part of the high temperature side lead and the low temperature side lead, and (b) is a cross section of the high temperature side lead. surface,
(C) Cross section of low temperature side lead

FIG. 11 is a configuration diagram of a connection portion between a room temperature terminal of the conventional superconducting device current lead shown in FIG. 9 and a power supply terminal of a power supply;
(A) is a plan view, (b) is a side view

[Explanation of symbols]

1 normal temperature terminal 2 high temperature side lead 3 low temperature side lead 4 low temperature terminal 5 superconducting coil 6 low temperature connecting conductor 7 vacuum insulation container 11 good conductive conductor 12, 12A outer cylinder 13 outer cylinder 14 oxide superconducting conductor 15 intermediate connecting conductor 20A columnar Oxide superconducting conductor 20B Cylindrical oxide superconducting conductor 20C, 20D, 20E Oxide superconducting conductor 21 Injection port 22 Discharge port 30 , 30A , 30B Connection conductor 31, 31A, 31B Oxide superconductor 32A, 32B Insulation pipe 33, 33A Vacuum container 34, 34A Liquid nitrogen container 35A, 35B Terminal lead 36 Injection port 37 Discharge port 38 Spacing piece 40 Liquid nitrogen tank 41 Pressure reducer 50 Power supply 51 Power supply terminal 52 Connection conductor

Claims (9)

[Claims] 1. A current lead for a superconducting device in which an exciting current is passed from an external power source to a superconducting coil housed in a vacuum heat insulation container and immersed in liquid helium, and a part of an attached conductor is decompressed liquid nitrogen. A current lead for a superconducting device, which is made of a conductor to be cooled. 2. A current lead for a superconducting device, wherein a good conductive conductor built in a high temperature side current lead and an oxide superconducting conductor built in a low temperature side lead are conductively connected in series through an intermediate connecting conductor, Intermediate connection conductor and good conductive conductor,
The current lead for a superconducting device according to claim 1, wherein the current lead is a conductor cooled with decompressed liquid nitrogen. 3. A connecting conductor for connecting a room temperature terminal provided at a room temperature end to a power supply terminal of an external power supply is a conductor arranged in a heat insulating container and cooled by decompressed liquid nitrogen. The current lead for a superconducting device according to claim 1. 4. The connection conductor for connecting a room temperature terminal provided at a room temperature end to a power supply terminal of an external power supply is formed by using one oxide superconductor or a plurality of oxide superconductors connected in parallel. A current lead for a superconducting device according to claim 3. 5. A conductor in which a pair of connecting conductors connected to room temperature terminals of a pair of current leads for a superconducting device connected to the same superconducting coil are placed in the same heat insulating container and cooled by decompressed liquid nitrogen. The current lead for a superconducting device according to claim 3 or 4, wherein 6. The heat insulating container for the connecting conductor comprises a liquid nitrogen container for storing decompressed liquid nitrogen and a vacuum container arranged outside the liquid nitrogen container, wherein at least the liquid nitrogen container and the vacuum container are liquid. The current lead for a superconducting device according to claim 3, 4 or 5, wherein the nitrogen container is made of an electrically insulating material. 7. A current lead for a superconducting device in which an exciting current is supplied from an external power source to a superconducting coil housed in a vacuum heat insulation container and immersed in liquid helium. A structure in which oxide superconducting conductors contained in leads are conductively connected in series via an intermediate connecting conductor, wherein the oxide superconducting conductor is a columnar conductor or a cylindrical conductor and a cylinder coaxially arranged around the conductor. A current lead for a superconducting device, comprising a parallel connection body with a conductor. 8. A current lead for a superconducting device, wherein an exciting current is supplied from an external power source to a superconducting coil housed in a vacuum heat insulation container and immersed in liquid helium. In a structure in which oxide superconducting conductors contained in leads are conductively connected in series through an intermediate connecting conductor, the oxide superconducting conductor is a columnar conductor or a cylindrical conductor and a plurality of coaxial cylinders arranged around the conductor. A current lead for a superconducting device, characterized in that the current lead comprises a series connection body in which the conductors are folded and connected in a radial direction with a gap therebetween. 9. A current lead for a superconducting device in which an exciting current is supplied from an external power source to a superconducting coil housed in a vacuum heat insulation container and immersed in liquid helium. In the one in which the oxide superconducting conductor contained in the lead is conductively connected in series via the intermediate connecting conductor, in the outer peripheral portion of the oxide superconducting conductor,
A series connection in which an intermediate connecting conductor in which both ends of the oxide superconducting conductor are conductively connected and an outer cylinder connected to the low temperature terminal are connected by folding a plurality of coaxial cylindrical members in the radial direction with a gap between them. A current lead for a superconducting device, which is composed of a body.