JPH04163811A - Noninductive magnetic shield type bushing using high temperature superconducting material - Google Patents

Abstract

PURPOSE:To maintain the cooling effect for a long period of time by enclosing a noninductive type conducting body of high temperature superconducting material with a magnetically shielding body, and providing a bushing, cooled by liquid nitrogen, in a housing vessel for superconductivity cooled by liquid helium. CONSTITUTION:A current flows through an outer member 9A and a superconductivity application apparatus 1 to a center member 9B when a direct current voltage is applied across rod-like terminals 13, 14. Thus, sufficient current feeding can be done, since the fluxes generated by the members cancel each other and a magnetic shielding body 8 hinders the penetration of a flux from the outside. And, the dissipation of cold from the liquid helium 3 decreases, since an electrically conducting body 9 and the shielding body 7 are cooled by liquid nitrogen 18 so that the liquid nitrogen 18 intervenes between liquid helium 3 and the atmosphere, and further since the conducting body 9 and the shielding body 7 are formed by a high temperature superconducting material which has low thermal conductivity. Thus, a required current can be fed in a superconductivity application apparatus, as well as the cooling effect can be maintained for a longer period.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a bushing that is attached to an equipment storage container for storing superconducting applied equipment such as a superconducting magnet and cooling the superconducting applied equipment with liquid helium. ,
For more details, please refer to the non-inductive magnetically shielded bushing made of high-temperature superconducting material, which maintains the cooling effect of liquid helium and also ensures sufficient current carrying capacity by minimizing the magnetic field generated during energization and the influence of external magnetic fields. Regarding.

(Prior Art) Conventionally, as shown in FIG. 4, an equipment storage container 23 for storing superconducting applied equipment 21 such as a superconducting magnet and cooling the superconducting applied equipment 21 with liquid helium 22 is equipped with a superconducting applied equipment 21. A power supply line 24, 25 from a power supply device that supplies the necessary power to the device 21 from the outside, and a lead wire 2 connected to the superconducting applied device 21 in liquid helium 22.
A bushing 28 is attached for electrically connecting the terminals 6 and 27.

This bushing 28 connects two electrodes 31 and 32 made of a good electrical conductor such as copper or silver-filled copper to an insulator 3.
The upper end of the electrode 31.32 is connected to the power supply line 24.25, and the lower end thereof is connected to the beam power line 26.27.

(Problems to be Solved by the Invention) The conventional bushing 28 has a metal electrode 31 that has good thermal conductivity between the extremely low temperature liquid helium 22 whose cooling temperature is 4°2K (Kelvin) and the atmosphere (room temperature). 32, the bushing 28 has a liquid helium cooling temperature (4.2K) and room temperature (for example, 313, 40K).
(°C). Therefore, there is a problem in that the cold heat of the liquid helium 22 rapidly dissipates in the bushing 28, increasing the amount of evaporation of the expensive liquid helium 22, and reducing the cooling effect of the liquid helium 22.

In order to prevent this, it would be necessary to cool the bushing 28'' using a cooling device (not shown), which would require a large amount of electricity to cool the bushing 28. .

Therefore, in the present invention, by configuring the current-carrying body of the bushing part using a high-temperature superconducting material with poor thermal conductivity in liquid nitrogen cooling, liquid helium can be cooled without using a special cooling device characterized by large cooling power. In addition, by configuring the current-carrying body in a non-inductive manner and surrounding the current-carrying body with a magnetic shield, the current of the high-temperature superconducting material, which has a small critical current under a magnetic field, can be maintained. The technical problem to be solved is to reduce the decrease in current flowing due to the influence of magnetic flux even in current-carrying bodies, and to ensure sufficient current carrying capacity.

(Means for solving the problem) The technical means for solving the above problem is to use a non-inductive magnetically shielded bushing made of high-temperature superconducting material to house superconducting application equipment manufactured using superconducting material. A device storage container that cools superconducting application equipment with liquid helium is provided with a case to fill with liquid nitrogen, and inside the case is a coaxial current-carrying body made of high-temperature superconducting material and a current-carrying body. A magnetic shielding body is arranged to surround the coaxial current-carrying body, and one end of the coaxial current-carrying body is connected to a power supply line from a power supply device that supplies the necessary power to the superconducting application equipment. , the other end is electrically connected to the superconducting application equipment.

(Function) According to the non-inductive magnetically shielded bushing using high-temperature superconducting material having the above configuration, the required power is supplied from the external power supply to the superconducting application equipment stored in the equipment storage container and cooled with liquid helium. When supplied, currents of equal magnitude and opposite direction are passed through the center conductor and the outer cylindrical conductor of the coaxial current carrying body using high temperature superconducting material.

Therefore, even if a large current flows through the coaxial current-carrying body, the generated magnetic flux cancels each other out. In addition, the external magnetic field is shielded by the Meissner effect of the magnetic shield placed so as to surround the coaxial current-carrying body, so the coaxial current-carrying body is not affected by the magnetic field, so the magnetic flux It becomes possible to extremely reduce the restriction of the current flowing due to
Sufficient current capacity can be secured.

In addition, since the coaxial current-carrying body and magnetic shield body are cooled by liquid nitrogen filled in the case, the liquid helium cooling temperature (4.2K) and room temperature (for example, 313K)
Because the liquid nitrogen cooling temperature (77K) exists between The cold heat of liquid helium is less likely to be dissipated directly into the atmosphere, and the amount of evaporation can be extremely reduced.

(Example) Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view showing the construction of a non-inductive magnetically shielded bushing using, for example, a ceramic-based high-temperature superconducting material.

As shown in FIG. 1, a superconducting application device 1 such as a superconducting magnet is housed in a device storage container 2 having a heat insulating structure. The equipment storage container 2 contains the required amount of liquid helium A.
3 is satisfied, and superconducting application equipment 1 is almost 4.2
It is cooled down.

Further, lead wires 4 and 5 are connected to the superconducting application equipment l.

On the other hand, a case 6 having a heat insulating structure is attached to the upper part of the equipment storage container 2 in a watertight manner.

A cylindrical magnetic shield 7 made of a ceramic-based high-temperature superconducting material is fixed inside the case 6 with its outer peripheral surface inserted into a hole formed in the equipment storage container 2. . A short and tall cylindrical insulating member 8 is attached to the inner diameter surface of the cylindrical magnetic shielding body 7, and a current carrying body 9 made of a high temperature superconducting material is fixed to the inner diameter surface of the insulating member 8. There is. The current-carrying body 9 is formed coaxially and is composed of a cylindrical outer member 9A, a cylindrical center member 9B, and an insulating member 9C interposed between the outer member 9A and the center member 9B. There is. Further, on the upper surface of the case 6, power supply lines 11 and 12 from a power supply device for supplying the necessary power to the superconducting application equipment 1 are provided.
Terminal board 15 to which rod-shaped terminals 13 and 14 to be connected are fixed
is installed airtight.

The lower end of the rod-shaped terminal 13.14 is connected to the rieet wire 16.1.
The outer member 9A and the center member 9B of the current-carrying body 9 are connected through 7.
connected to the top end of each. On the other hand, the lead wires 4 and 5 of the superconducting application equipment 1 are connected to the lower ends of the outer member 9A and the center member 9B of the current carrying body 9, respectively.

In the above configuration, a required amount of liquid nitrogen 18 is injected into the case 6, and the magnetic shield body 7 formed of a high-temperature superconducting material and the current carrying body 9 are heated to the liquid nitrogen cooling temperature (
77K).

Note that FIG. 2 is a perspective view of the cylindrical magnetic shield 7, the cylindrical insulating member 8, and the current carrying body 9 assembled together, and FIG. is shown in a plan view.

In the above configuration, the case 6, the magnetic shield body 7. Insulating member 8. Outer member 9A constituting current carrying body 9
and a central member 9B and an insulating member 9C.

Rod-shaped terminals 13 and 14. Terminal board 15. A bushing 20 is made up of the liquid nitrogen 18 and the liquid nitrogen 18 .

Next, the operation of this embodiment will be explained.

When the required power is output from the power supply device, the required current is applied to the superconducting application equipment l.

Now, when direct current is applied to superconducting application equipment 1,
When the positive electrode voltage of the power supply device is applied to the rod-shaped terminal 13 and the negative electrode voltage is applied to the rod-shaped terminal 14, the current flows from the rod-shaped terminal 13→
It flows in the direction of lead wire 16 → outer member 9A → lead wire 4 → superconducting application equipment 1 → lead wire 5 → center member 9B → lead wire 17 → rod-shaped terminal 14. Therefore, the outer member 9A and the center member 9B of the current-carrying body 9 have the same size, and currents flow in opposite directions. Therefore, since the magnetic flux generated from the outer member 9A and the magnetic flux generated from the central member 9B cancel each other out, the current carrying body 9 becomes a non-inductive current carrying body.

On the other hand, the magnetic shielding body 7 arranged so as to surround the current carrying body 9 prevents the intrusion of magnetic flux from the outside by utilizing the Meissner effect (external magnetic field exclusion phenomenon) of the high temperature superconducting material.

Furthermore, since the ceramic-based high-temperature superconducting material has a low thermal conductivity, the cold heat of the liquid helium 3 is conducted to the liquid nitrogen 18, and the degree to which the cooling effect of the liquid helium 3 is reduced is extremely small. Furthermore, since the bushing 20 cooled by the liquid nitrogen 18 is interposed between the liquid helium 3 and the atmosphere, that is, room temperature, the dissipation of the cold heat of the liquid helium 3 is extremely reduced, so that the evaporation of the expensive liquid helium 3 is reduced. Superconducting application equipment using liquid helium 3 by reducing the amount
It has the characteristic of being able to maintain its cooling effect for a long time.

(Effects of the Invention) As described above, according to the present invention, a non-inductive current carrying body is formed using a high temperature superconducting material, the current carrying body is surrounded by a magnetic shielding body, and the current carrying body and the magnetic A bushing configured to cool the shield body with liquid nitrogen was attached to an equipment storage container for cooling superconducting application equipment with liquid helium, so even if current flows through the current-carrying object, magnetic flux from the current-carrying object will not be generated. In addition, the magnetic shield prevents the intrusion of magnetic flux from the outside, so even a current-carrying body made of high-temperature superconducting material with a small critical current under a magnetic field is sufficient. It has the effect of being able to pass a certain amount of current.

Furthermore, since there is a bushing cooled by liquid nitrogen between the liquid helium in the equipment storage container and room temperature, the dissipation of the cold heat of the liquid helium is extremely small, reducing the amount of evaporation of the expensive liquid helium. The effect is that the cooling effect of liquid helium on superconducting application equipment can be maintained for a long period of time.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the construction of an embodiment of the present invention from a road body perspective, FIG. 2 is a perspective view showing the main parts of a bushing, and FIG. 3 is a plan view thereof. FIG. 4 is a sectional view showing a conventional technique. 1: Superconducting applied equipment 2: Equipment storage container 3, liquid helium 4: Lead wire 5: Lead wire 6: Case 7: Magnetic shield body 8: Insulating member 9: Current carrying body 9A: Outer member 9B = Center member 9C: Insulation Member 11: Lead wire of power supply device 12: Lead wire of power supply device 13: Rod-shaped electrode 14: Rod-shaped electrode 15: Terminal plate I6: Reed wire 17: Lead wire 18: Liquid nitrogen 20: Bushing

Claims (1)

[Claims] A superconducting application device manufactured using a superconducting material,
It is attached to an equipment storage container configured to cool the superconducting applied equipment with liquid helium, and is connected to a power supply line from an external power supply device that supplies the necessary power to the superconducting applied equipment and the liquid helium. A bushing for electrically connecting the superconducting application equipment, comprising a case filled with liquid nitrogen, and inside the case, a coaxial current-carrying body made of a high-temperature superconducting material,
A magnetic shielding body arranged to surround the coaxial current carrying body is provided, and one end of the coaxial current carrying body is connected to a power supply line from the power supply device, and the other end is connected to the power supply line from the power supply device. A non-inductive magnetically shielded bushing using a high-temperature superconducting material, characterized in that the above-mentioned superconducting application equipment is electrically connected to the part.