JPH0786642A - Conduction cooling superconduction magnet device - Google Patents

Abstract

PURPOSE:To provide a conduction cooling superconducting magnet device which prevents the reduction of critical current at current leads. CONSTITUTION:A conduction cooling superconducting magnet device 1 consists of a refrigerator 7, a superconducting coil 5 that can be cooled by the refrigerator 7, and current leads 6 to feed the superconducting coil 5 with power. The current leads 6 are composed of oxide high temperature superconductor. In the conduction cooling superconducting magnet device 1, a cooling stage 7B of the freezer 7 is in contact with the superconducting coil 5, and a superconducting magnetic shields 51 are formed around the perimeter of the current leads 6. The superconducting magnetic shields 51 are composed of metal superconducting material, and are in contact with the cooling stage 7B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conduction cooling type superconducting magnet device.

[0002]

2. Description of the Related Art A conventional conduction cooling type superconducting magnet device is
Some include a refrigerator, a superconducting coil that can be cooled by the refrigerator, and a current lead that supplies power to the superconducting coil (for example, Japanese Patent Application No. 3-104042).

Further, in the above-mentioned conduction cooling type superconducting magnet device, there is a conventional one in which the current lead is composed of an oxide high temperature superconductor.

[0004]

As described above, conventionally, the current lead for feeding the superconducting coil has been constituted by the high temperature oxide superconductor, but the critical current of the high temperature oxide superconductor is It is known to be greatly reduced by the magnetic field.

Therefore, when an oxide high temperature superconductor is used as a current lead of various superconducting coils, it is necessary to prevent the critical current from decreasing by providing some kind of magnetic shield against the leakage magnetic field from the superconducting magnet.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a conduction cooling type superconducting magnet device which prevents a decrease in critical current in a current lead.

[0007]

According to the present invention, a refrigerator, a superconducting coil that can be cooled by the refrigerator, and a current lead for supplying power to the superconducting coil are provided, and the current lead has a high oxide temperature. In a conduction cooling type superconducting magnet device composed of a superconductor, the superconducting coil is brought into contact with the cooling stage of the refrigerator, and a superconducting magnetic shield is provided on the outer circumference of the current lead, and the superconducting magnetic shield is made of metal. A conduction cooling type superconducting magnet device is obtained which is made of a superconducting material and is in contact with the cooling stage.

[0008]

In the present invention, the superconducting magnetic shield made of a metallic superconductor is provided on the outer circumference of the current lead, and this superconducting magnetic shield is cooled together with the superconducting coil by the refrigerator. Thus, the magnetic shield for the current lead can be efficiently performed.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a conduction cooling type superconducting magnet device according to an embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a partial longitudinal sectional view of a conduction cooling type superconducting magnet device. This conduction cooling type superconducting magnet device 1 includes a base 2, a vacuum container (cryostat) 3, a heat shield plate 4, a superconducting coil 5, a pair of positive and negative high temperature superconducting current leads 6, and a cold storage refrigerator 7. And an external power supply 8.

The vacuum container 3 is evacuated and has a heat shield plate 4, a superconducting coil 5, a high-temperature superconducting current flow lead 6, a first cooling stage 7A and a second cooling stage of the cold storage refrigerator 7. And 7B.

The heat shield plate 4 is the first of the cold storage type refrigerator 7.
While being fixed in contact with the stage cooling stage 7A, heat is prevented from entering the superconducting coil 5 and the high temperature superconducting current lead 6 inside thereof.

The superconducting coil 5 is formed by winding a superconducting wire 10 around a coil winding frame 9, and an outer periphery cooling copper block 11 is fastened to the outer periphery thereof as a cooling promoting member.

The coil winding frame 9 comprises a winding core 9A and end flanges 9B integrally formed at both upper and lower ends of the winding core 9A.

By fixing the outer peripheral cooling copper block 11 and the coil winding frame 9 to the second stage cooling stage 7B of the regenerator 7, the superconducting wire 10 can be efficiently cooled to a cryogenic temperature.

FIG. 2 is a partially cutaway vertical sectional view showing a concrete structure of the copper block 11 for cooling the outer periphery, and FIG.
It is a sectional view taken along line III. The outer peripheral cooling copper block 11 is divided into an equal number of intervals in the circumferential direction, for example, an arbitrary number, for example, three arc-shaped unit block portions 11A, 11B, 11.
It is composed of C.

Arc-shaped unit block portions 11A, 11B, 1
At least one eddy current preventing electric insulating material 12 for preventing eddy current at the time of quench and a copper sheet 13 are interposed between the 1C's, and a predetermined amount is provided from the outer circumference of the superconducting wire 10 by bolts 14. It is tightened with a tightening force to improve mutual contact and improve thermal contact.

The adhesion can be adjusted by adjusting the thickness with a shim (not shown).

Further, a low temperature grease having good thermal conductivity may be filled between the outer peripheral cooling copper block 11 and the superconducting wire 10.

Returning to FIG. 1, high-temperature superconducting current lead 6
Is provided with a pair of positive and negative electrodes, and the current lead terminal 15
And an external power source 8 through a normal conducting current lead wire 16, and the end on the high temperature side is the first of the regenerator type refrigerator 7.
The low temperature side end portion is attached to the second cooling stage 7A and the second cooling stage 7B is attached to the second cooling stage 7A. The high-temperature superconducting current lead 6 is made of an oxide high-temperature superconductor.

The regenerator 7 is an optional refrigerator such as a GM refrigerator, the first stage cooling stage 7A of which can cool to a liquid nitrogen temperature of around 77K and the second stage 7B of which can cool. It is possible to cool to an extremely low temperature of 4 to 10K.

Therefore, the normal-current conductive flow lead wire 16 supplies power in the range from the room temperature (300K) portion of the vacuum container 3 to the temperature (70K) of the first stage cooling stage 7A of the regenerator 7 and reaches a high temperature. The superconducting current lead 6 supplies electric power in the temperature range of the first cooling stage 7A to the second cooling stage 7B.

High temperature side electrode 17 of high temperature superconducting current lead 6
Is connected to the normal-current conductive flow lead wire 16 and is also connected to the first-stage cooling stage 7A of the regenerator 7 via the heat anchor copper wire 18 and the high temperature side insulating material 19 such as the high temperature side aluminum nitride plate. Has been done.

Low temperature side electrode 20 of high temperature superconducting current lead 6
Is a low temperature side insulating material 2 such as a low temperature side aluminum nitride plate
1 is connected to and fixed to the second cooling stage 7B of the regenerator 7 via bolts 1 as a fixed end,
It is connected to the superconducting wire 10 of the superconducting coil 5.

The high-temperature superconducting current lead 6 made of an oxide high-temperature superconductor has a characteristic that its current-carrying capability (current density) deteriorates when it is installed in a strong magnetic field, so that the magnetic field to the lead body is reduced. Function is required.

For this reason, a cylindrical superconducting magnetic shield 51 is provided around the high-temperature superconducting current lead 6.

The superconducting magnetic shield 51 is made of a metallic superconducting material such as NbTi and has a structure in which the outside of the high-temperature superconducting current lead 6 is annularly covered, and the magnetic field applied from the superconducting coil 5 to the high-temperature superconducting current lead 6 is applied. It is decreasing.

Further, the superconducting magnetic shield 51 can directly cool the second stage cooling stage 7B of the regenerator 7 to cool it to an extremely low temperature (for example, 5K or less).
The superconducting material forming the superconducting magnetic shield 51 can be maintained at a critical temperature (for example, the critical temperature of NbTi is 9.8K) or lower.

Specifically, the superconducting magnetic shield 51 is fixed to the low temperature side insulating material 21 which is in contact with the second cooling stage 7B.

In the conduction cooling type superconducting magnet device 1 having such a configuration, the positive electrode current from the external power source 8 is first introduced to the normal conducting current lead wire 16 via the current lead terminal 15, and then successively to the high temperature side electrode 17. The superconducting coil 5 is excited by being guided to the high temperature superconducting current lead 6 and the low temperature side electrode 20.

The negative electrode current returns to the external power source 8 in the course opposite to the above.

The thermal contact between the superconducting coil 5 and the second stage cooling stage 7B of the regenerator 7 is performed via the coil winding frame 9. In addition to this heat conduction, the second stage cooling stage is also provided. Heat conduction is also performed through the outer peripheral cooling copper block 11 that is in contact with 7B.

Therefore, heat is exchanged not only from the inner surface side of the superconducting coil 5 but also from the entire outer surface of the superconducting coil 5, so that the initial cooling of the superconducting coil 5 can be performed quickly and the inside of the superconducting coil 5 can be quickly cooled. Is cooled to a uniform temperature.

Further, the superconducting magnetic shield 51 cooled to an extremely low temperature effectively shields the magnetism with respect to the high temperature superconducting current lead 6.

[0035]

The conduction cooling type superconducting magnet device of the present invention comprises:
The magnetic shield of the current lead can be effectively performed by the superconducting current lead at a low temperature, and as a result, high shield characteristics can be obtained and the reduction of the critical current in the current lead can be prevented.

[Brief description of drawings]

FIG. 1 is a partial vertical cross-sectional view of a conduction cooling type superconducting magnet device according to an embodiment of the present invention.

FIG. 2 is a partially cutaway vertical sectional view showing a specific configuration of a copper block for cooling the outer circumference of the conduction cooling type superconducting magnet device shown in FIG.

3 is a sectional view taken along line III-III in FIG.

[Explanation of symbols]

 1 conduction cooling type superconducting electromagnet device 2 base 3 vacuum container 4 heat shield plate 5 superconducting coil 6 high temperature superconducting current lead 7 regenerator 7A first cooling stage 7B second cooling stage 8 external power supply 9 coil reel 9A Winding core 9B End flange 10 Superconducting wire 11 Peripheral cooling copper block 51 Superconducting magnetic shield

Claims (2)

[Claims] 1. A conduction cooling type including a refrigerator, a superconducting coil that can be cooled by the refrigerator, and a current lead for supplying power to the superconducting coil, the current lead being composed of an oxide high-temperature superconductor. In the superconducting magnet device, the superconducting coil is brought into contact with the cooling stage of the refrigerator, and a superconducting magnetic shield is provided on the outer circumference of the current lead, and the superconducting magnetic shield is made of a metal-based superconducting material, and the cooling stage is provided. A conduction cooling type superconducting magnet device characterized in that it is in contact with 2. A first cooling stage for the refrigerator
The step cooling stage and a second step cooling stage having a temperature lower than that of the first step cooling stage are provided, and the superconducting coil and the superconducting magnetic shield are brought into contact with the second step cooling stage. Conduction cooling type superconducting magnet device.