JPH0786643A - Conduction cooling superconducting magnet device - Google Patents

Abstract

PURPOSE:To reduce leakage magnetic fields from superconducting coils and prevent the reduction of critical current at oxide high temperature superconducting current leads, by encircling the superconducting coil with ferrous ceramic magnetic shield member having a higher permeability. CONSTITUTION:The title conduction cooling superconducting magnet device consists of a cold storage type freezer 7 comprising a first and a second cooling stages A, B, a superconducting coil 5 placed on the second cooling stage B, and high temperature superconducting current leads 6 connected with the superconducting coil 5 through electrodes 20. A magnetic shield member is installed at both ends and around the perimeter, of the superconducting coil 5. The magnetic shield member consists of a cylindrical side magnetic shield member 19A, a disk-like upper magnetic shield member 19B and lower magnetic shield member 19C. This will reduce leakage magnetic fields from the superconducting coil 5, and prevent the reduction of critical current at the high temperature superconducting current leads 6 at the leads.

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 electromagnet device.

[0002]

2. Description of the Related Art FIG. 4 is a partial longitudinal sectional view of a conduction cooling type superconducting electromagnet apparatus according to a conventional example. As shown in FIG. 4, the conduction cooling type superconducting electromagnet apparatus 50 includes a base 2, a vacuum container 3 called a cryostat, a heat shield plate 4,
It is provided with a superconducting coil 5 ', a pair of positive and negative electrode high temperature superconducting current leads 6, a regenerator 7, and an external power source 8.

The high temperature superconducting current lead 6 has its high temperature side end attached to the first stage cooling stage 7A of the regenerator 7 and its low temperature side end attached to the second stage cooling stage 7B, respectively.
It is connected to an external power source 8 via a normal conducting current lead wire 13 in the vacuum vessel 3 and a current lead terminal 12 provided at the bottom of the vacuum vessel 3. The superconducting coil 5 is covered with a copper block 11 for cooling the outer periphery as a cooling promoting material.

In the regenerator 7, the first cooling stage 7A can cool the liquid nitrogen temperature to around 77K,
The second cooling stage 7B is configured to be able to cool to an extremely low temperature of 4 to 10K.

Therefore, the normal-current conductive current lead 13 supplies power in the range from the room temperature (300K) portion of the vacuum container 3 to the temperature (70K) of the first cooling stage 7A of the regenerator 7, and the high-temperature superconducting current flows. The lead 6 supplies power in the temperature range of the first cooling stage 7A to the second cooling stage 7B.

In the conduction cooling type superconducting electromagnet apparatus 50 having such a structure, the positive electrode current from the external power source 8 first passes through the current lead terminal 12 and then the normal conducting current lead wire 1.
3 to the high temperature side electrode 14, the high temperature superconducting current lead 6 and the low temperature side electrode 20, and the superconducting coil 5 is excited. Incidentally, the negative current returns to the external power source 8 in the course opposite to the above.

[0007]

However, the high temperature superconducting current lead 6 feeding the superconducting coil 5 is composed of an oxide high temperature superconductor, and the critical current of this oxide superconductor is greatly affected by an external magnetic field. It is known to decline.

Therefore, when an oxide high-temperature superconductor is used as a current lead of various superconducting coils, a certain magnetic shield is applied to the leakage magnetic field from the superconducting magnet to prevent a decrease in the critical current. There is a need.

Therefore, the first technical problem of the present invention is to reduce the leakage magnetic field from the superconducting coil in the oxide superconducting current lead, and to prevent the decrease of the critical current of the oxide high temperature superconducting current lead. It is to provide a cooling type superconducting electromagnet device.

Further, the second technical problem of the present invention is that the superconducting coil can be cooled by conduction even when sufficient thermal contact between the cooling stage for conduction cooling and the superconducting coil cannot be ensured. It is to provide a conduction cooling type superconducting electromagnet device.

[0011]

According to the present invention, in a conduction cooling type superconducting electromagnet apparatus in which a superconducting coil is fixed on a cooling stage of a regenerator, an iron system having a large magnetic permeability is provided around the superconducting coil. A conduction cooling type superconducting electromagnet device is obtained which is characterized by being surrounded by a metal magnetic shield member.

According to the present invention, in the conduction cooling type superconducting electromagnet apparatus, the magnetic shield member is provided at least between the cooling stage and the superconducting coil, and the superconducting coil has a large thermal conductivity in the surroundings. A conduction cooling type superconducting electromagnet device is obtained which is provided with a cooling promoting member.

[0013]

In the present invention, by surrounding the superconducting coil with a magnetic shield member made of an iron-based metal, the leakage magnetic field from the superconducting coil in the oxide superconducting current lead portion can be reduced, and the oxide high temperature superconducting current lead can be reduced. To prevent a decrease in the critical current.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a partial longitudinal sectional view of a conduction cooling type superconducting electromagnet apparatus according to an embodiment of the present invention. As shown in FIG. 1, the conduction cooling type superconducting electromagnet apparatus 1 includes a vacuum container 3,
The regenerative refrigerator 7 including the first cooling stage 7A and the second cooling stage 7B, the superconducting coil 5 placed on the second cooling stage 7B, and the superconducting coil 5 are connected to the superconducting coil 5 via electrodes 20. And a high temperature superconducting current lead 6 connected to a pair of low temperature side electrodes 14 provided penetrating the first cooling stage 7A, and a heat shield plate 4 covering the superconducting coil 5 with the first cooling stage 7A as the bottom. And a high-temperature side electrode 14 and a current conducting terminal 13 connected between the current lead terminal 12 provided at the bottom of the vacuum chamber 3. The current lead terminal 12 is connected to an external power source (not shown).

The regenerator 7 includes a second cooling stage 7B for cooling the liquid helium temperature and a liquid nitrogen temperature 77.
First stage cooling stage 7A for cooling up to K, second cooling section D provided therebetween, fixing plate 7C for contacting the bottom of vacuum container 3, first stage cooling stage 7A and fixing plate 7C, the 1st cooling part E provided between 7C, and the fixed plate 7
It is configured by including an external introduction portion 7F from C.

The superconducting coil 5 is a coil winding frame 9, a winding portion 10 made of a superconducting wire wound around the coil winding frame 9, and a cooling accelerating member fixed by tightening the outer circumferences thereof for cooling the outer circumference. A copper block 11 is provided, and magnetic shield members 19 are attached to both ends and the outer periphery of the copper block 11. The coil winding frame 9 includes a winding core 9A and end flanges 9B and 9B integrally formed at upper and lower ends of the winding core 9A.
It is composed of C and.

The magnetic shield member 19 is the superconducting coil 5
Of the cylindrical side magnetic shield member 19A arranged further outside the outer peripheral cooling copper block 11 and the disk-shaped upper magnetic shield member 19B arranged outside the coil winding frame end flanges 9B and 9C. And a lower magnetic shield member 19C.

The magnetic shield member 19 is made of a material having a high magnetic permeability, such as pure iron or permalloy.

The high temperature superconducting current lead 6 is composed of the high temperature insulator 1
Low temperature side electrode 20 and high temperature side electrode 1 fixed via 7
It is fixed between four. A thermal anchor copper wire 18 is provided at the lower end of the high temperature side electrode 14, and one end thereof is joined to a high temperature insulator 17.

By thus surrounding the superconducting coil with the magnetic shield member 19, the leakage magnetic field from the superconducting coil 5 in the high temperature superconducting current lead 6 is reduced, and the critical current of the acid high temperature superconducting current lead 6 is reduced. Can be prevented.

The heat shield plate 4 is fixed in contact with the second stage cooling stage 7B of the regenerator 7 and reduces heat invasion into the superconducting coil 5 and the high-temperature superconducting current lead 6 inside thereof. . As described above, the magnetic shield member 19 is provided between the second cooling stage 7B of the refrigerator and the superconducting coil 5, and the first cooling stage 7 for conduction cooling is provided.
Even when the thermal contact between A and the superconducting coil 5 cannot be sufficiently secured, the superconducting coil can be cooled by conduction by providing the external cooling copper block 11 as the cooling promoting member. Reference numeral 3B in the figure is a magnetic field utilization space.

FIG. 2 is a longitudinal sectional view of a main part showing a concrete structure of the magnetic shield member 19, and FIG. 3 is a sectional view taken along the line I--I of FIG. By dividing it into equiangular intervals,
This is composed of two arc-shaped members 19A1 and 19A2. Similarly, the external cooling copper block 11 is also divided into two pieces 1.
Insulating plate 22 for preventing eddy current, copper sheet 23 for 1A and 11B
It is configured by joining the end portions with interposing.

As shown in FIG. 3, each arcuate member 19A1,
An electrical insulating material 20 for preventing an eddy current at the time of quenching is interposed between the opposite end surfaces of 19A2. Both the upper and lower magnetic shield members 19B and 19C have the same donut-shaped disk shape. In order not to disturb the uniformity of the magnetic field distribution of the superconducting coil 5, the magnetic shield members 5 having the same shape are symmetrically arranged above and below the superconducting coil.

[0025]

As described above, according to the present invention, the leakage magnetic field from the superconducting coil in the high temperature superconducting current lead is reduced by surrounding the superconducting coil with the magnetic shield member made of iron-based metal. Let
It is possible to provide a conduction cooling type superconducting electromagnet device capable of preventing a decrease in the critical current of a high temperature superconducting current lead.

Further, according to the present invention, since there is a magnetic shield member between the cooling stage of the refrigerator and the superconducting coil, sufficient thermal contact between the cooling stage for conduction cooling and the superconducting coil cannot be ensured. Even in such a case, it is possible to provide a conduction cooling type superconducting electromagnet device capable of cooling the superconducting coil by conduction by providing the cooling promoting member.

[Brief description of drawings]

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

FIG. 2 is a longitudinal sectional view of an essential part showing a specific configuration of a magnetic shield member 19 of FIG.

3 is a cross-sectional view taken along the line I-I of FIG.

FIG. 4 is a partial vertical cross-sectional view of a conduction cooling type superconducting electromagnet device according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conduction cooling type superconducting electromagnet device 4 Heat shield plate 5 Superconducting coil 6 High temperature superconducting current lead 7A First stage cooling stage 7B Second stage cooling stage 9 Coil reel 9A Winding core 9B End flange 10 Winding part 11 For outer circumference cooling Copper block 13 Normal electric current flow lead 19 Magnetic shield member 19A Side magnetic shield member 19B Upper magnetic shield member 19C Lower magnetic shield member 19A1, 19A2 Arc member 20 Low temperature side electrode 21 Electrical insulating material

Claims (2)

[Claims] 1. A conduction cooling type superconducting electromagnet apparatus in which a superconducting coil is fixed on a cooling stage of a regenerator, wherein the superconducting coil is surrounded by an iron-based metal magnetic shield member having a high magnetic permeability. A conduction cooling type superconducting electromagnet device characterized by: 2. The conduction cooling type superconducting electromagnet apparatus according to claim 1, wherein the magnetic shield member is provided at least between the cooling stage and the superconducting coil, and the superconducting coil has a large thermal conductivity in the surroundings. A conduction cooling type superconducting electromagnet device, which is provided with a cooling promoting member.