JPH06163249A - Superconducting coil bobbin - Google Patents

Abstract

PURPOSE:To obtain a superconducting coil bobbin capable of evading troubles caused by the quenching of a superconducting coil which is driven in a vacuum atmosphere solid conduction cooling. CONSTITUTION:A bobbin main body 11 made of high thermal conductivity metal is accommodated in a case 13, and an accommodation chamber is formed between the main body and the case. The accommodation chamber is filled with cold storing material 12 using Er3Ni or the like. Thereby the heat capacity of the whole bobbin is increased, and the temperature rise of the coil at the time of quenching is restrained by the cold stored in the cold storing material 12 when the coil is cooled. Hence the burnout or the like of the coil can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bobbin for a superconducting coil which has an effect of increasing the heat capacity and preventing the temperature rise of the coil.

[0002]

2. Description of the Related Art A winding frame for a superconducting coil is generally made of metal such as stainless steel or GFRP (glass fiber reinforced plastic) simply processed into a desired shape. However, this type of bobbin has a low thermal conductivity and lacks heat dissipation capability during coil quench.

Therefore, in order to dissipate heat generated during coil quenching to the surroundings as much as possible, the applicant of the present invention has disclosed in JP-A-63-192203 that the surface of the reel is coated with a good heat transfer material such as diamond or alumina. is suggesting.

[0004]

The winding frame proposed by the present applicant is effective when the superconducting coil is placed in the atmosphere or in a refrigerant (liquid helium, liquid nitrogen, etc.) and is used. Is less effective when placed in a vacuum atmosphere.

For example, in a newly developed solid conduction cooling system, as shown in FIG. 2, a superconducting coil 1 is installed in a vacuum chamber 8 and a refrigerator 3 is connected to this coil to cool the refrigerator. Cold heat is transmitted from the stage 4 via the connecting member 2 of the good heat conductor. In this case, since the surroundings are in a vacuum atmosphere, cooling by diffusion cannot be expected.

On the other hand, the regenerator type small refrigerator used for solid conduction cooling has a small cooling capacity (the one currently reported is several hundreds of mW at 4.2 k), and therefore, cooling of the superconducting coil is performed in this cooling system. If only the capacity of the refrigerator is used, the cooling of the coil during quenching will be insufficient due to insufficient capacity of the refrigerator, and the coil will be damaged (for example, the enamel insulator of the superconducting wire or the gap between the bobbin and the conductor). In some cases, the insulator will be damaged).

Further, since an excessive heat load is applied to the cooling stage of the refrigerator, the refrigerator is also adversely affected.

Since the conventional reel has a small heat capacity, when used in a vacuum atmosphere, it is necessary to successively supply cold heat from the refrigerator, which is commensurate with the amount of heat absorbed from the coil. This means that the cooling of the superconducting coil depends only on the capacity of the refrigerator, and thus the above problems are unavoidable. Alternatively, in order to avoid this problem, the current density during operation of the superconducting coil (magnet) has to be reduced.

An object of the present invention is to devise a winding frame to solve the above problems.

[0010]

SUMMARY OF THE INVENTION In order to eliminate the above problems, the present invention forms a storage chamber at a position along the surface of the reel body and fills it with a regenerator material to cover the entire reel. Increase the heat capacity.

[0011]

The superconducting coil is cooled to a predetermined temperature before operating the magnet, and cold heat is stored in the regenerator material at this time. Then, if the cold heat supplied from the refrigerator when the quench occurs is insufficient, the shortage is compensated by the regenerator material, thereby suppressing the coil temperature rise and the heat load increase of the refrigerator due to the quench.

[0012]

FIG. 1 shows an example of a winding frame for a superconducting coil according to the present invention.

As shown in the figure, the reel 10 has a structure in which the reel main body 11, the regenerator material 12 and the case 13 are stacked in three layers.

The reel body 11 and the case 13 are both made of a metal having a good thermal conductivity (eg, copper).

The case 13 is provided for the purpose of surrounding the inner peripheral surface of the reel body 11 and the outer surfaces of the upper and lower flanges and creating a storage chamber for the regenerator material between these surfaces. This case 1
In No. 3, some of the walls are joined after the winding frame main body 11 is housed and finished in the shape of the drawing.

As the regenerator material 12, Er ₃ Ni, Ho _1.5 Er _1.5 Ru or the like having a large specific heat (volume specific heat) at the operating temperature of the superconducting coil (4.2 to 10 k cryogenic temperature) is used.
It is also possible to add Pb having a large specific heat at a temperature of 10 k or more. Fig. 3 shows Toshiba Review 1991 Vol. 46N
o. 5 shows the temperature-dependent data of the volumetric specific heat of Er ₃ Ni and Pb reported in FIG.

These cold storage materials are preferably fine particles having a large volume specific surface area. This is filled in the storage chamber created between the reel body 11 and the case 13. The storage chamber is finally sealed so that the communication with the vacuum atmosphere in which the superconducting coil is stored is cut off.

In addition, in order to improve the heat conduction between the reel body 11 and the case 13, it is desirable that an inert gas (nitrogen or helium) be sealed in the closed storage chamber filled with the regenerator material 12. . Further, it is also effective to provide an inorganic insulating thin film having good electrothermal property on the surface of the reel main body 11 or the case 13 so that heat can be smoothly diffused throughout the reel.

The superconducting wire 14 such as NbTi wire is wound around the winding frame 10 thus constructed to make a superconducting coil, and the coil is used to construct a solid conduction cooling type superconducting magnet system as shown in FIG. Reference numeral 5 in FIG. 2 denotes a first cooling stage of a refrigerator for cooling the radiant heat shield plate 6. Another cooling stage may be arranged between this stage 5 and the low temperature side cooling stage 4. Reference numeral 7 is an energization lead, and 9 is a compressor. In this system, the regenerator material can also be incorporated in the connecting member 2.

In this way, the refrigerator 3 is operated to cool the superconducting coil 1. At this time, the cold storage material in the reel stores cold heat. Therefore, the time until the coil is cooled to a predetermined temperature is longer than before, but in an emergency (when the amount of cold heat supplied from the refrigerator is insufficient), the shortage of cold heat is supplied from the regenerator material. As a result, the temperature rise width of the coil is reduced and the adverse effect on the refrigerator is reduced. In particular, when the regenerator material 2 mainly contains Er ₃ Ni or the like and contains Pb therein, the heat flowing out from the coil is mainly absorbed by Pb, so that the heat load of the refrigerator is rapidly increased and the heat load is increased. The effect of suppressing the imbalance of distribution is sufficiently exerted, and more preferable results are obtained.

[0021]

As described above, since the reel of the present invention is provided with the regenerator material to increase the heat capacity, when the superconducting coil is cooled by the refrigerator having a small capacity and is operated in the vacuum atmosphere. Even if quenching occurs, it is possible to suppress the temperature rise of the coil, prevent burnout, and avoid adverse effects on the refrigerator.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a winding frame of the present invention partially broken away.

FIG. 2 is a diagram showing a solid conduction cooling type magnet system.

FIG. 3 is a graph showing temperature-dependent data of volumetric specific heat of the regenerator material.

[Explanation of symbols]

 10 reel 11 reel body 12 cold storage material 13 case 14 superconducting wire

Claims (1)

[Claims] 1. A bobbin for a superconducting coil, which is formed by forming a storage chamber at a position along a surface of a bobbin main body and filling a regenerator material therein.