JP2001093721A - High-temperature superconducting magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-temperature superconducting magnet which has superior mechanical strength and heat conductivity characteristics, and is compact and highly reliable. SOLUTION: A high-temperature superconducting conductor of a pure silver matrix and a high-temperature superconductive conductor of a silver alloy matrix are varied in their use rate, according to use conditions. Consequently, a proper high-temperature superconductor can be actualized, which has mechanical properties and thermal properties that correspond to the use conditions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a high-temperature superconducting magnet having a high-temperature superconducting coil formed by winding a superconducting conductor comprising a plurality of high-temperature superconducting wires.

[0002]

2. Description of the Related Art In a conventional high-temperature superconducting magnet system, a Bi222 using a pure silver sheath as a matrix material is used as a high-temperature superconductor forming a high-temperature superconducting coil.
3 and Bi2212 wires are widely used. And
In such a wire, a tape-shaped high-temperature superconducting wire has been developed in order to improve the superconducting properties.

Since this tape wire has a low performance with respect to a magnetic field perpendicular to the tape surface, the vertical magnetic field is reduced when designing a high-temperature superconducting coil. That is, in order to increase the critical current of the conductor disposed at the position where the magnetic field perpendicular to the tape surface is strongest in the cross section of the HTS coil, the number of wires constituting the conductor is increased and the number of turns is reduced. I have to.

In high-temperature superconducting wires, pure silver is used for the sheath material. However, the mechanical strength of the wire is not strong, and it is generally used together with a reinforcing material such as stainless steel. In addition, alloy sheathed wires have been developed for the purpose of facilitating distortion resistance and handling of high-temperature superconducting wires, but the Young's modulus of the alloy sheath material is not so large as compared with that of the silver sheath material. For this reason, a reinforcing material is used in a high-temperature superconducting coil to which a large electromagnetic force is applied even when an alloy sheath material is used.

[0005] Further, since the alloy sheath wire has a lower thermal conductivity than the pure silver sheath wire, various heat transfer paths are additionally provided to improve the heat conduction characteristics in the high-temperature superconducting coil.

[0006]

However, the conventional high-temperature superconducting magnet has the following problems. (1) Grading, in which the number of wires constituting the high-temperature superconducting conductor is increased at a place where the load factor is high, results in lowering the current density of the high-temperature superconducting coil. (2) As a countermeasure against electromagnetic force, in the conductor configuration using an alloy sheath wire and further incorporating a reinforcing material, the heat conduction characteristics in the cross section of the high-temperature superconducting coil are deteriorated, and an additional conductive wire is provided to compensate for this. The heat path results in a reduction in the current density of the HTS coil. (3) The high-temperature superconducting coil has a large flow loss. In particular, in the case of the high-temperature superconducting magnet, the temperature rise of the high-temperature superconducting coil due to an increase in heat generation (flow loss) due to energization is difficult to achieve a thermal balance with a further increase in flow loss. Quench may occur at the end.

An object of the present invention is to provide a compact and highly reliable high-temperature superconducting magnet having excellent mechanical strength and heat transfer characteristics.

[0008]

The high-temperature superconducting magnet according to the present invention is a high-temperature superconducting magnet having a high-temperature superconducting coil formed by winding a superconducting conductor formed of a plurality of tape-shaped high-temperature superconducting wires. The high-temperature superconducting coil is formed using the superconducting conductor in which a high-temperature superconducting wire of a pure silver matrix and a high-temperature superconducting wire of a silver alloy matrix are mixed.

In the high-temperature superconducting magnet according to the first aspect of the present invention, the usage ratio of the high-temperature superconducting wire of the pure silver matrix and the high-temperature superconducting wire of the silver alloy matrix is changed in accordance with the use conditions. As a result, an appropriate high-temperature superconducting conductor having both mechanical and thermal properties according to the use conditions can be realized.

In the high-temperature superconducting magnet according to a second aspect of the present invention, in the first aspect of the present invention, the superconducting conductor located at the outer peripheral portion of the cross section of the high-temperature superconducting coil is formed of a silver alloy matrix as compared with the inner superconducting conductor. It is characterized in that the ratio of the high-temperature superconducting wire is increased.

In the high-temperature superconducting magnet according to the second aspect of the present invention, the ratio of the high-temperature superconducting wire of the silver alloy matrix in the superconducting conductor located at the outer peripheral portion of the cross section of the high-temperature superconducting coil is larger than that of the inner superconducting conductor. Thereby, grading can be performed without reducing the number of turns of the high-temperature superconducting coil, and heat generation of the coil can be suppressed.

The high-temperature superconducting magnet according to a third aspect of the present invention is the high-temperature superconducting magnet according to the first aspect, wherein at least one wire located at the end of the superconducting conductor is made of a silver alloy matrix having an insulating coating. It is characterized by using a line.

[0013] In the high-temperature superconducting magnet according to the third aspect of the present invention, the high-temperature superconducting wire of the silver alloy matrix provided with the insulating coating positioned at the end of the superconducting conductor maintains insulation from other high-temperature superconducting wires. Therefore, a coil having a high current density can be provided without requiring an additional insulating material.

According to a fourth aspect of the present invention, there is provided a high-temperature superconducting magnet according to the first aspect, wherein at least one wire of the high-temperature superconducting wire of the superconducting conductor is formed by co-winding a high heat conducting material. Features.

In the high-temperature superconducting magnet according to the fourth aspect of the present invention, the high-temperature superconducting wire co-wound with the high heat conductive material promotes heat conduction. Therefore, the heat transfer characteristic can be improved without disposing an extra material.

According to a fifth aspect of the present invention, there is provided a high-temperature superconducting magnet according to the fourth aspect, wherein the high thermal conductive material is
It is characterized by being an alumina dispersion strengthened steel.

In the high-temperature superconducting magnet according to the fifth aspect of the present invention, not only the heat transfer characteristic but also the mechanical strength is maintained by the alumina dispersion strengthened steel.

According to a sixth aspect of the present invention, in the high temperature superconducting magnet according to the fourth aspect, when the high temperature superconducting coil is used at a temperature of 20 K or more, aluminum or an alloy thereof is used as the high thermal conductive material. When the high-temperature superconducting coil is used at a temperature of 35K or more, copper or an alloy thereof is used.

In the high-temperature superconducting magnet according to the sixth aspect of the present invention, the high-thermal-conductivity material is changed according to the operating temperature condition of the high-temperature superconducting coil. At a temperature of 20K or more, aluminum or its alloy suitable for it is used, and at a temperature of 35K or more, copper or its alloy is used.

According to a seventh aspect of the present invention, there is provided a high-temperature superconducting magnet according to the first aspect, wherein the shield plate surrounding the high-temperature superconducting coil comprises a tape material made of a high thermal conductor on a surface through which a magnetic flux escapes. It is characterized by being formed into a pancake-type disk or a solenoid-type cylinder by being wound with an insulating material interposed therebetween, and formed by arranging a high thermal conductor in a direction crossing between the turns.

In the high-temperature superconducting magnet according to the seventh aspect of the present invention, the shield plate is formed by winding a tape material of a high thermal conductor together with an insulating material on the surface of the shield plate from which the magnetic flux escapes. Place the conductor.
This improves heat conduction and suppresses eddy currents.

According to an eighth aspect of the present invention, in the high-temperature superconducting magnet according to the first aspect of the present invention, the superconducting conductor for connecting the high-temperature superconducting coil and the high-temperature superconducting current lead is made of a flexible superconducting twisted wire or It is characterized by being formed by a parallel conductor electrically connected in the longitudinal direction and a metal reinforcing conductor arranged in parallel to the parallel conductor.

In the high-temperature superconducting magnet according to the present invention, when the parallel conductor of the superconducting conductor for connecting the high-temperature superconducting coil and the high-temperature superconducting current lead breaks,
Since a bypass circuit having a metal reinforcing conductor is provided, burning of the high-temperature superconducting coil is prevented.

According to a ninth aspect of the present invention, in the high-temperature superconducting magnet according to the first aspect of the present invention, the reinforcing material for the superconducting conductor wound with the high-temperature superconducting wire is a metal having at least one side edge having a round edge. It is characterized by being a tape.

In the high-temperature superconducting magnet according to the ninth aspect of the present invention, since the metal tape wound with the high-temperature superconducting wire has a rounded edge on one side, the risk of dielectric breakdown is reduced.

According to a tenth aspect of the present invention, in the high-temperature superconducting magnet according to the first aspect of the present invention, the reinforcing material of the superconducting conductor wound together with the high-temperature superconducting wire has at least a facing surface which is smooth and has an edge portion. It is characterized by being formed by stacking two or more insulating reinforcing tapes having a round shape.

In the high-temperature superconducting magnet according to the tenth aspect, insulation between turns is maintained by two or more insulating reinforcing tapes wound together with the high-temperature superconducting wire.

According to an eleventh aspect of the present invention, in the high-temperature superconducting magnet according to the first aspect, the superconducting conductor is formed by winding glass fiber, carbon fiber, or a fiber reinforced plastic of these fibers in parallel with the high-temperature superconducting wire. It is characterized by being formed.

In the high-temperature superconducting magnet according to the eleventh aspect, insulation between turns is maintained by glass fiber, carbon fiber, or a fiber-reinforced plastic of these.

In a twelfth aspect of the present invention, in the high-temperature superconducting magnet according to the first aspect of the present invention, the reinforcing material for the superconducting conductor wound together with the high-temperature superconducting wire is from room temperature to the operating temperature of the high-temperature superconducting coil. The linear expansion coefficient is larger than that of the high-temperature superconducting wire.

In the high-temperature superconducting magnet according to the twelfth aspect of the present invention, in the range from room temperature to the operating temperature of the high-temperature superconducting coil, a compressive force is applied to the high-temperature superconducting wire by the reinforcing material to prevent bending distortion and tensile distortion from occurring. I do.

According to a thirteenth aspect of the present invention, there is provided the high-temperature superconducting magnet according to the first aspect, wherein the impregnating material impregnated between the high-temperature superconducting wires has a linear expansion coefficient from room temperature to a coil operating temperature. It is characterized by being larger than that of.

In the high-temperature superconducting magnet according to the thirteenth aspect of the present invention, the impregnating material impregnated between the high-temperature superconducting wires prevents compressive force from being applied to the high-temperature superconducting wire to prevent bending distortion and tensile distortion.

According to a fourteenth aspect of the present invention, in the high-temperature superconducting magnet according to the first aspect of the present invention, the reinforcing material for the superconducting conductor wound together with the high-temperature superconducting wire has a tensile stress that is greater than that of the high-temperature superconducting wire. It is also characterized by having been enlarged.

In the high-temperature superconducting magnet according to the fourteenth aspect of the present invention, the reinforcing material wound in a state having a tensile stress in advance prevents a bending strain and a tensile strain from being generated by applying a compressive force to the high-temperature superconducting wire. I do.

According to a fifteenth aspect of the present invention, in the high-temperature superconducting magnet according to the first aspect, the reinforcing material for the superconducting conductor wound together with the high-temperature superconducting wire is wound outside the high-temperature superconducting conductor. It is characterized by the following.

In the high-temperature superconducting magnet according to the fifteenth aspect of the present invention, the reinforcing material wound around the high-temperature superconducting conductor prevents a bending force and a tensile strain from being generated by applying a compressive force to the high-temperature superconducting wire.

A high-temperature superconducting magnet according to a sixteenth aspect of the present invention is the high-temperature superconducting magnet according to the first aspect, wherein a metal tape or a ceramic tape having a strength higher than that of the wire is joined to one surface of the high-temperature superconducting wire. Is formed.

In the high-temperature superconducting magnet according to the sixteenth aspect of the present invention, a metal tape or a ceramic tape applies a compressive force to the high-temperature superconducting wire to prevent the occurrence of bending strain and tensile strain.

A high-temperature superconducting magnet according to a seventeenth aspect is characterized in that, in the sixteenth aspect, a high-strength tape is wound around the high-temperature superconducting conductor.

In the high-temperature superconducting magnet according to the seventeenth aspect of the present invention, a high-strength tape wound around the outside of the high-temperature superconducting conductor can be used to apply a compressive force to the high-temperature superconducting wire to prevent bending distortion and tensile distortion. .

The high-temperature superconducting magnet according to the eighteenth aspect of the present invention is the high-temperature superconducting magnet having a high-temperature superconducting coil formed by winding a plurality of high-temperature superconducting wires in parallel while insulating each other. Each of the high-temperature superconducting wires is electrically short-circuited at a position where the inductance of the wire is equal.

In the high-temperature superconducting magnet according to the eighteenth aspect of the present invention, each of the high-temperature superconducting wires provided in parallel is electrically short-circuited at a position where the inductance of each of the wires is equal, and the critical current of the high-temperature superconducting wire is reduced. In the case where the values are different or when a defect occurs in a part of the wire, distribution of the current flowing through each wire is facilitated and the stability of the coil is improved.

The high-temperature superconducting magnet according to the nineteenth aspect of the present invention is formed by winding a plurality of high-temperature superconducting wires in parallel, and impregnating the impregnating material in the longitudinal direction between the high-temperature superconducting wires provided in parallel. In a high-temperature superconducting magnet having a high-temperature superconducting coil, a metal powder having high electric conductivity is added to the impregnating material.

In the high-temperature superconducting magnet according to the nineteenth aspect of the present invention, a plurality of high-temperature superconducting wires are respectively wound in parallel, and the impregnating material in the longitudinal direction between the high-temperature superconducting wires provided in parallel extends over the entire length in the longitudinal direction of the wire. In this case, stable electrical conduction is possible even in a case where many electrical defects are involved.

According to a twentieth aspect of the present invention, there is provided a high temperature superconducting magnet for cooling a high temperature superconducting coil from a low heat source of a refrigerator via a heat transfer member.
The temperature of the low heat source may be lower than the temperature at which the thermal conductivity of the material having the maximum thermal resistance among the heat transfer members becomes maximum.

In the high-temperature superconducting magnet according to the twentieth aspect, the temperature of the low heat source of the refrigerator is kept lower than the temperature at which the material having the maximum thermal resistance among the heat transfer members has the maximum thermal conductivity. As a result, the temperature rise of the high-temperature superconducting coil caused by an increase in the temperature difference of the heat transfer member caused by heat generated when the high-temperature superconducting coil is supplied to the rated current is suppressed.

[0048]

Embodiments of the present invention will be described below. FIG. 1 is an explanatory view of a superconducting conductor 1 used for a high-temperature superconducting coil of a high-temperature superconducting magnet according to a first embodiment of the present invention.

In FIG. 1, a superconducting conductor 1 includes a high-temperature superconducting wire (pure silver matrix wire) 2 of a pure silver matrix formed in a tape shape and a high-temperature superconducting wire (silver alloy matrix wire) of a silver alloy matrix formed in a tape shape. 3) are mixed. FIG. 1 shows a superconducting conductor 1 in which one silver alloy matrix line 3 and three pure silver matrix lines 3 are mixed. Then, the superconducting conductor 1 is turned to form a high-temperature superconducting coil of the high-temperature superconducting magnet.

For example, in an oxide superconducting wire such as Bi2223, a pure silver sheath or a silver alloy sheath is used as a matrix material in order to obtain a large critical current. Pure silver sheath has higher electric conductivity and thermal conductivity than silver alloy sheath, and generates less heat when the superconducting state is broken. In addition, there is a feature that the temperature distribution in the high-temperature superconducting coil is hardly formed with the same heat generation. On the other hand, the mechanical properties of the silver alloy sheath are better than those of the pure silver sheath in both strain resistance and stress resistance.

Therefore, in the first embodiment, in order to provide a superconducting conductor 1 having both the advantages of a pure silver sheath and a silver alloy sheath, the temperature margin is strict and the temperature difference in the high-temperature superconducting coil needs to be reduced. Has a conductor configuration mainly composed of a pure silver sheath. On the other hand, a high-temperature superconducting coil that generates a strong magnetic field and has a large hoop stress has a conductor structure mainly composed of a silver alloy sheath.

As described above, in the first embodiment, the superconducting conductor 1 is formed by mixing the pure silver matrix wire 2 and the alloy matrix wire 3, and the superconducting conductor 1 is turned to form the high-temperature superconducting coil of the high-temperature superconducting magnet. To form Thus, by changing the use ratio of the pure silver matrix wire 2 and the alloy matrix wire 3 in accordance with the use conditions of the high-temperature superconducting coil, an appropriate superconducting conductor 1 having both mechanical properties and thermal properties according to the use conditions is obtained. This can be realized, and the use of additional heat conductive materials and reinforcing materials can be suppressed.

Next, a second embodiment of the present invention will be described. FIG. 2 is an explanatory diagram of a superconducting conductor 1 used for a high-temperature superconducting coil of a high-temperature superconducting magnet according to a second embodiment of the present invention. In the second embodiment, a superconducting conductor 1a located at an outer peripheral portion of a cross section of a high-temperature superconducting coil 4 is provided.
In the figure, the ratio of the silver alloy matrix wire 3 is larger than that of the internal superconducting conductors 1b and 1c.

FIG. 2 shows a pancake-type high-temperature superconducting coil 4, in which the superconducting conductor 1 is composed of four wires. All four superconducting conductors 1a located on the outer peripheral portion of the cross section of the high-temperature superconducting coil 4 are formed of silver alloy matrix wires 3 so as to maintain mechanical strength. The superconducting conductor 1b inside the superconducting conductor 1b is formed using three silver alloy matrix lines 3 and one pure silver matrix line 2, and the superconducting conductor 1c at the center is composed of three pure silver matrix lines 2 and one pure silver matrix line. And the reinforcing material 5 of the above.

That is, the superconducting conductor 1a used for the pancake coil located on the outer peripheral portion of the cross section of the high-temperature superconducting coil 4 is entirely formed by using the silver alloy matrix wire 3 and becomes pure silver as the inner pancake becomes. The ratio of the matrix lines 2 is increased. Further, in the pancake coil located at the center of the high-temperature superconducting coil 4, three pure silver matrix wires 2 and silver alloy matrix wires 3
, A reinforcing material 5 such as stainless steel is used.

That is, a reinforcing material 5 such as stainless steel is arranged in the central pancake coil where the largest electromagnetic force (hoop stress or compressive force) acts as the high-temperature superconducting coil 4.
The coil is configured to withstand both hoop stress and compressive force. In addition, by arranging a large number of pure silver matrix wires 2 having high thermal conductivity in the central pancake coil, which is difficult to take a cooling path, excellent characteristics are obtained from a thermal viewpoint.

This is from the viewpoint of the strength of the constituent materials:
In consideration of the order of pure silver sheath, silver alloy sheath, and stainless steel from the thermal point of view, stainless steel, silver alloy sheath, and pure silver sheath are in order. The pure silver matrix wire 2 is provided with a function as a heat conductive material to provide a conductor whose function is clearly separated. Therefore, this is an effective measure against the central pancake coil which is disadvantageous both thermally and mechanically.

On the other hand, the pancake coil at the end of the high-temperature superconducting coil 4 has the severest electric field due to the large magnetic field in the direction perpendicular to the tape surface of the high-temperature superconducting wire, but is thermally cooled. Easy, mechanically does not apply so much electromagnetic force. Therefore, the pancake coil at the end of the high-temperature superconducting coil 4 has the silver alloy matrix wire 3 having a stress resistance of two to three times the performance of a pure silver sheath and also has a mechanical strength. , The critical current as the superconducting conductor 1 is improved.
That is, the margin can be increased without lowering the current density of the pancake coil at the end of the high-temperature superconducting coil 4 which is the most severe electrically.

In the second embodiment, the proportion of the alloy matrix wire 3 in the buncake coil located on the outer periphery of the cross section of the high-temperature superconducting coil 4 is larger than that in the inner pancake coil. Grading can be performed without reducing the number of turns of the coil 4. Therefore, the heat generation of the high-temperature superconducting coil can be suppressed, and the cooling characteristics of the internal pancake coil can be improved.

Next, a third embodiment of the present invention will be described. FIG. 3 is an explanatory view of a superconducting conductor 1 used for a high-temperature superconducting coil of a high-temperature superconducting magnet according to a third embodiment of the present invention. In the third embodiment, at least one wire located at the end of the superconducting conductor 1 uses a silver alloy matrix wire 3 provided with an insulating coating 6.

FIG. 3 shows a superconducting conductor 1 in which an insulating coating 6 is applied to the silver alloy matrix wire 3 at the upper end. Other high-temperature superconducting wires may be pure silver matrix wires 2 or silver alloy matrix wires 3. Thereby, for example, the superconducting conductor 1 in which a plurality of high-temperature superconducting wires are laminated
When manufacturing a pancake coil, insulation between turns can be ensured.

Here, in order to increase the average current density of the high-temperature superconducting coil, it is preferable that the insulation between turns is as thin as possible. However, it is very difficult to co-wind an insulating tape such as Kapton at the time of winding. It is difficult and it is difficult to ensure reliable insulation. In particular, when a high-temperature superconducting coil is manufactured by applying a resin by impregnation or the like, it is difficult to reliably incorporate the insulating layer because Kapton is slippery.

On the other hand, when a reinforcing material or the like is included in the wire constituting the superconducting conductor 1, it is proposed that the reinforcing material be insulated and then co-wound to provide insulation between turns. Superconducting conductor 1 which does not use reinforcing material
Not applicable in case of Further, since the pure silver matrix wire 2 is very fragile, it is very difficult to apply an insulating coating.

Therefore, in the third embodiment, as shown in FIG. 3, the superconducting conductor 1 is formed by previously insulating the silver alloy matrix wire 3 which can be insulated and coated, so that no additional insulating material is required. Becomes

Next, a fourth embodiment of the present invention will be described. FIG. 4 is an explanatory view of a superconducting conductor 1 used for a high-temperature superconducting coil of a high-temperature superconducting magnet according to a fourth embodiment of the present invention. In the fourth embodiment, at least one wire of the high-temperature superconducting wire of the superconducting conductor 1 is formed by co-winding the high heat conducting material 7.
When the high-temperature superconducting coil is used at a temperature of 20 K or more, aluminum or an alloy thereof is used as the high heat conductive material 7. When mechanical strength is required, alumina dispersion strengthened steel is used as the high heat conductive material 7. Used. When the high-temperature superconducting coil is used at a temperature of 35K or more, copper or an alloy thereof is used.

FIG. 4 shows one provided with one high thermal conductive material 7, and the other high-temperature superconducting wire may be a pure silver matrix wire 2 or a silver alloy matrix wire 3.
The high thermal conductive material 7 is made of a pure silver matrix wire 2 or a silver alloy matrix wire 3 at a temperature at which a high-temperature superconducting coil is used.
It has a higher thermal conductivity than.

Here, when a high-temperature superconducting coil using the pure silver matrix wire 2 is used at a temperature of 20 K or less,
Since the thermal conductivity of silver is very large, a special high thermal conductive material 7
However, when the operating temperature of the high-temperature superconducting coil needs to be 20 K or more, the high heat conductive material 7 is required. This is because the thermal conductivity of pure silver or a silver alloy becomes lower than aluminum at a temperature of 20K or more, and becomes lower than copper at a temperature of 30K or more.

Therefore, when the high-temperature superconducting coil is used at a temperature of 20 K or more, aluminum or an alloy thereof is used as the high heat-conducting material 7 and the high-temperature superconducting coil is 3
When used at a temperature of 5K or more, copper or an alloy thereof is used.

When high strength of the high temperature superconducting coil is required in addition to the heat transfer performance inside the high temperature superconducting coil, alumina dispersion strengthened copper is used as a high heat conducting material. As a result, the high-temperature superconducting magnet operated at a temperature of 20 K or more has excellent mechanical strength and thermal conductivity,
A high-temperature superconducting coil without lowering the conductor current density can be manufactured.

According to the fourth embodiment, at the temperature at which the high-temperature superconducting coil is used, a high heat conductive material having a higher heat conductivity is co-wound than the pure silver matrix wire 2 or the silver alloy matrix wire 3 used for the wire. Then, by co-winding a material such as alumina dispersion strengthened steel, a high-performance high-temperature superconducting magnet can be provided without disposing an extra functional material.

Next, a fifth embodiment of the present invention will be described. FIG. 5 is an explanatory view of a shield plate 8 used for a high-temperature superconducting coil of a high-temperature superconducting magnet according to a fifth embodiment of the present invention.

In FIG. 5, a shield plate 8 is arranged so as to surround the high-temperature superconducting coil, and shields the high-temperature superconducting coil. For example, in the case of a pancake coil, the shield plate 8 is formed in a pancake disk, and in the case of a solenoid, the shield plate 8 is formed in a solenoid cylinder. FIG. 5 shows a shield plate 8 of a pancake type disk.

The tape material 9 of the high thermal conductor is wound up in a pancake shape with the insulating material 10 disposed thereon.
That is, the tape material 9 of the high thermal conductor is provided on the surface from which the magnetic flux escapes.
Are wound in a state where the insulating material 10 is arranged between the turns. Then, in the direction crossing the turn, the high heat conductor 1
1 is arranged.

As a member arranged to surround the superconducting coil, there is a radiation shield plate or a coil cooling plate. Hereinafter, these will be described as shield plates. As a material of the shield plate, a tape material such as silver, aluminum, copper, etc. is wound on the shield plate on the surface from which magnetic flux escapes, and a bancake-type disk or solenoid type cylinder is wound with the insulating material placed between turns. It is constituted using.

Here, the materials usually used for the shield plate are copper, aluminum and the like which are excellent in thermal conductivity at low temperature, but these materials have large electric conductivity and generate large eddy current. In particular, a large eddy current is induced in the shield plate arranged to make one turn with respect to the magnetic flux generated by the superconducting coil, causing a large loss. In addition, a large electromagnetic force is applied, and in the worst case, the device is destroyed. . For this reason, it is customary to insert an insulating layer into the shield plate so as to cut this one turn. However, the insulating layer for one turn cut naturally hinders heat conduction, and the shield plate itself The eddy current generated by the magnetic flux that escapes cannot be suppressed.

On the other hand, in the fifth embodiment, since the shield plate has a coil shape, the eddy current can be cut without obstructing the heat conduction in the circumferential direction. Further, in order to promote heat transfer in the radial direction, it is sufficient to dispose a heat conductor in the radial direction via an insulating layer, and a shield plate having extremely excellent performance against eddy current can be obtained.

Next, a sixth embodiment of the present invention will be described. FIG. 6 is an explanatory diagram of a high-temperature superconducting magnet according to a sixth embodiment of the present invention. In the sixth embodiment, the superconducting conductor 13 for connecting the high-temperature superconducting coil 4 and the high-temperature superconducting current lead 12 is a flexible superconducting stranded wire or a parallel conductor 14 electrically connected in the longitudinal direction. And a metal reinforcing conductor 15 arranged in parallel to the metal reinforcing conductor 15.

In FIG. 6, superconducting conductor 1 for connecting high-temperature superconducting coil 4 and high-temperature superconducting current lead 12 is shown.
Reference numeral 3 denotes a flexible superconducting stranded wire or a parallel conductor 14 electrically connected in the longitudinal direction, and a metal reinforcing conductor 15 arranged in parallel with the parallel conductor.

The high-temperature superconducting conductor of the high-temperature superconducting coil 4 is made of a pure silver matrix wire 2 as its matrix material.
Alternatively, a silver alloy matrix wire 3 is used, but it cannot be said that it has excellent mechanical properties. In such a high-temperature superconducting magnet, when a part of the circuit including the high-temperature superconducting coil 4 and the power supply is cut, the energy stored in the high-temperature superconducting coil 4 is instantaneously released. It may cause burning. The weak point of the high-temperature superconducting coil 4 using a fragile wire is that such a risk of breakage is high.

Therefore, in the sixth embodiment, a stranded wire conductor or a parallel conductor 14 having flexibility is used as the superconducting conductor 13 for connecting the high-temperature superconducting coil 4 and the high-temperature superconducting current lead 12, and the superconducting conductor 13 is connected in parallel to this. A metal reinforcing conductor 15 having excellent mechanical properties is disposed at the second position. This allows
Even when the parallel conductor 14 is broken, a bypass circuit of the metal reinforcing conductor 15 is provided, so that the worst case such as burning of the high-temperature superconducting coil 4 can be avoided.

Next, a seventh embodiment of the present invention will be described. FIG. 7 is an explanatory view of a superconducting conductor used for a high-temperature superconducting coil of a high-temperature superconducting magnet according to a seventh embodiment of the present invention.

FIG. 7A shows a reinforcing material 5 of a superconducting conductor 1 wound around a high-temperature superconducting wire using at least one side edge of a metal tape having a round shape R. 7 (b) is a reinforcing material 5 of the superconducting conductor 1 wound together with the high-temperature superconducting wire, two or more insulating reinforcing tapes 5a having at least opposing surfaces smooth and having a rounded edge. 5b is formed by superposing 5b.

As shown in FIG. 7A, when a superconducting conductor 1 is formed by laminating a plurality of pure silver matrix wires 2 or silver alloy matrix wires 3 and a plurality of reinforcing members 5, an edge portion of at least one surface of the reinforcing members 5 is formed. It has a round shape R to reduce the risk of dielectric breakdown. In order to realize these shapes, when manufacturing the metal tape as the reinforcing member 5, the cutting direction is always set to one direction, and burrs are not always formed on one side. Further, it is possible to provide the reinforcing material 5 in which the edges of the four corners have a round shape R by rolling and crushing the round wire more completely.

On the other hand, as shown in FIG. 7 (b), two or more reinforcing tapes having at least a smooth surface facing each other and a round edge are superposed, and a resin 16 is impregnated therebetween. Thus, inter-turn insulation can be realized by the resin immersion resin 16 without special insulating coating. In particular, complete inter-turn insulation can be realized by mixing particles such as filler into the resin 16 and using a reinforcing tape material having a smooth surface with a smaller surface roughness than the particle diameter.

Further, this reinforcing tape was used as a thermosetting resin F
In the case of manufacturing a high-temperature superconducting coil by fiber-reinforced plastic such as RP, particularly by impregnation, it is possible to realize more complete inter-turn insulation by winding a glass fiber or a carbon fiber itself to form a high-temperature superconducting coil.

According to the seventh embodiment, superconducting conductor 1
By forming at least one edge portion of the reinforcing member 5 having the round shape R, the risk of dielectric breakdown can be reduced. In addition, since the reinforcing member 5 has a structure in which two or more reinforcing tapes are stacked, a special insulating coating can be eliminated. Furthermore, complete inter-turn insulation can be realized by coating and winding glass fiber and carbon fiber.

Next, an eighth embodiment of the present invention will be described. FIG. 8 is an explanatory diagram of a superconducting conductor used for a high-temperature superconducting coil of a high-temperature superconducting magnet according to an eighth embodiment of the present invention.

In the eighth embodiment, as shown in FIG. 8, a compressive force is applied to the pure silver matrix wire 2 or the silver alloy matrix wire 3 by the reinforcing material 5, and the pure silver matrix wire 2 which is a high-temperature superconducting wire is used. Alternatively, the occurrence of bending strain or tensile strain in the silver alloy matrix wire 3 is prevented.

It is known that the pure silver matrix wire 2 or the silver alloy matrix wire 3 is susceptible to bending strain and tensile strain, and that the pure silver matrix wire 2 has a bending strain and tensile strain of about 0.2% as service limits. Have been. Also,
In the silver alloy matrix wire 3 having improved strain characteristics, the limit is 0.3% to 0.4% for the strain characteristics, and it is very strong against the compressive strain, and the characteristics are up to about 0.6%. It is known that there is no deterioration.

Therefore, in the eighth embodiment, a compressive force is applied to the pure silver matrix wire 2 or the silver alloy matrix wire 3. First, a wire material of a tape-like pure silver matrix wire 2 or a silver alloy matrix wire 3 is reinforced with a reinforcing material 5.
To form a high-temperature superconducting coil. At this time, a reinforcing tape having a linear expansion coefficient from room temperature to the operating temperature of the high-temperature superconducting coil that is larger than that of the high-temperature superconducting wire is used. Thereby, a compression force is applied to the high-temperature superconducting wire when cooling the high-temperature superconducting coil.

Further, in the impregnated coil in which the impregnating material is impregnated between the high-temperature superconducting wires, the impregnating material having a higher linear expansion coefficient from room temperature to the coil operating temperature than that of the high-temperature superconducting wire is used.

Further, in a high-temperature superconducting coil manufactured by winding a high-temperature superconducting wire together with a reinforcing tape, the winding tension (tensile stress) of the reinforcing tape as the reinforcing material 5 is made larger than the tensile stress of the high-temperature superconducting wire. A compressive force is applied to the high-temperature superconducting wire.

Further, in a high-temperature superconducting coil manufactured by winding a high-temperature superconducting wire together with a metal tape, a metal tape as a reinforcing material 5 is wound outside the tape-shaped high-temperature superconducting wire, and the high-temperature superconducting wire is wound by the metal tape. By compressing, a compressive force is applied to the high-temperature superconducting wire.

Further, a metal tape or ceramic tape having a higher strength than the wire is joined to one surface of the high-temperature superconducting wire, and the high-strength tape is wound so as to be arranged outside the coil, thereby compressing the high-temperature superconducting wire. Apply force.

According to the eighth embodiment, a compressive force is applied in advance during winding or cooling of the high-temperature superconducting
By applying a compressive force to the extent, the wire performance of the high-temperature superconducting wire can be maximized.

Next, a ninth embodiment of the present invention will be described. FIG. 9 is an explanatory diagram of a superconducting conductor used for a high-temperature superconducting coil of a high-temperature superconducting magnet according to a ninth embodiment of the present invention. FIG. 9A shows a case where each of the high-temperature superconducting wires provided in parallel is electrically short-circuited at a position where the inductances L1 and L2 of the wires are equal, and FIG. Shows a high-temperature superconducting coil impregnating material 17 formed by impregnating the impregnating material 17 in the longitudinal direction between the high-temperature superconducting wires provided in parallel with a metal powder having high electric conductivity added to the impregnating material 17. ing.

As shown in FIG. 9A, a superconducting coil is formed by aligning the inductances L1 and L2 of the insulated wires. Then, the inductances L1 and L2 of each green element
Are electrically short-circuited at a position P where Thus, when the critical current of the high-temperature superconducting wire is different, or when a defect occurs in a part of the wire, the distribution of the current flowing through each wire can be easily changed.

For example, among the inductances L1 and L2 in the figure, when the inductance at the diagonal position is defective or the critical current is low, the current can be redistributed via the short-circuit point P provided in the middle. A wire with good characteristics can be selected and flowed. In the case of a completely insulated parallel strand, such a current distribution does not occur, and in such a case, a defective portion or a portion having a low critical current always flows.

When there are many defects in the wire, it is preferable to reduce the steady-state loss at the expense of the AC loss.
In such a case, as shown in FIG. 9B, the impregnating material 17 extends between the wires arranged in parallel over the entire length in the longitudinal direction.
Is electrically short-circuited by mixing the metal powder with the metal powder. That is, a metal powder is mixed with an epoxy resin as an impregnating material, and an electrical short circuit between wires is obtained by contact of the metal powder.

According to the ninth embodiment, in a superconducting coil in which the inductance of each insulated wire is uniform,
Since the wires are electrically short-circuited at the position where the inductance of each wire is equal, the distribution of the current flowing through each wire when the critical current of the superconducting wire is different or a portion of the wire is defective And the effect of increasing the stability of the high-temperature superconducting coil is obtained. In addition, by making electrical contact over the entire length of the wire in the longitudinal direction, stable conduction can be achieved even when many defects are included.

Next, a tenth embodiment of the present invention will be described. FIG. 10 is an explanatory diagram of a high-temperature superconducting magnet according to a tenth embodiment of the present invention. In the tenth embodiment, the heat transfer members 19a, 19b
A high-temperature superconducting magnet that cools the high-temperature superconducting coil 4 via the heat transfer member 19a, 19b, in which the temperature of the heat source lower than the temperature at which the thermal conductivity of the material exhibiting the maximum thermal resistance becomes the maximum is lower. It is.

The high-temperature superconducting coil 4 is housed in a vacuum vessel 20, and a refrigerator 18 for cooling the high-temperature superconducting coil 4 is installed outside the vacuum vessel 20. The heat transfer members 19a and 19b from the low heat source of the refrigerator 18 to the high temperature superconducting coil 4 in the vacuum vessel 20 are usually made of aluminum or copper. For this reason, materials that contribute to heat conduction as heat transfer paths include pure silver and silver alloy used for the superconducting wire, and heat transfer members 1 disposed inside or outside the high-temperature superconducting coil 4.
Aluminum and copper constituting 9a and 19b. The thermal conductivity of these materials varies greatly depending on the type, purity, or temperature of the material. Due to heat load such as heat generation and penetration heat when the high-temperature superconducting coil 4 is energized to the rated current,
These produce a temperature difference.

The temperature of the high-temperature superconducting coil 4 rises due to this temperature difference, and the heat generation further increases. As a result of repeating this phenomenon, if the increased heat load becomes larger than the cooling capacity of the refrigerator 18, the high-temperature superconducting coil 4 will quench.

In order to suppress this phenomenon as much as possible, the heat conductivity of the material constituting the heat transfer path increases due to the temperature rise in a temperature region where the increase in heat generation is slower than the temperature rise of the high-temperature superconducting coil 4. Select the temperature range. This makes it possible to suppress a rise in the temperature of the high-temperature superconducting coil 4. At least heat transfer members 19a, 19
Such a condition can be realized by lowering the temperature of the heat source lower than the temperature at which the thermal conductivity of b becomes the maximum.

When the operating temperature of the high-temperature superconducting coil 4 (that is, the temperature of the low heat source) is designed to be about 20 K, usually, most pure metal materials such as pure aluminum and copper used as the heat transfer members 19a and 19b are maximum. If the temperature exceeds the temperature indicating the thermal conductivity and the heat load due to heat generation increases,
The heat conductivity decreases with the temperature rise of 9a and 19b, and as a result, the temperature rise further increases.

On the other hand, when the operating temperature of the high-temperature superconducting coil 4 is set to 10 K or less, that is, an operating temperature within a range in which the thermal conductivity of the heat transfer members 19a and 19b such as copper and aluminum increases as the temperature increases. In some cases, 20
The above-described effects can be achieved by using sapphire having a thermal conductivity of copper, aluminum, silver, or the like having a temperature of K or more and diamond having a thermal conductivity of 25 K or more. In the case of sapphire, the temperature at which the thermal conductivity is maximum is about 35K, and the temperature rise during energization of the high-temperature superconducting coil 4 designed at an operating temperature of 20K can be minimized.

According to the tenth embodiment, the temperature of the high-temperature superconducting coil 4 caused by the increase in the temperature difference of the heat transfer path caused by the heat generated when the high-temperature superconducting coil 4 is supplied to the rated current, In a temperature region where the increase in heat generation is slower than the temperature rise of the coil 4, the temperature can be suppressed by selecting a temperature region in which the thermal conductivity of the material constituting the heat transfer path increases due to the temperature rise.

[0108]

As described above, according to the present invention, it is possible to save the reinforcing member and the heat transfer member, and furthermore, to make the high-temperature superconducting magnet in the superconducting state, suitable for the operating temperature of the high-temperature superconducting coil. By selecting a cooling member, a compact and highly reliable high-temperature superconducting magnet can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a superconducting conductor used for a high-temperature superconducting coil of a high-temperature superconducting magnet according to a first embodiment of the present invention.

FIG. 2 is an explanatory view of a superconducting conductor used for a high-temperature superconducting coil of a high-temperature superconducting magnet according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram of a superconducting conductor used for a high-temperature superconducting coil of a high-temperature superconducting magnet according to a third embodiment of the present invention.

FIG. 4 is an explanatory view of a superconducting conductor used for a high-temperature superconducting coil of a high-temperature superconducting magnet according to a fourth embodiment of the present invention.

FIG. 5 is an explanatory view of a shield plate used for a high-temperature superconducting coil of a high-temperature superconducting magnet according to a fifth embodiment of the present invention.

FIG. 6 is an explanatory diagram of a high-temperature superconducting magnet according to a sixth embodiment of the present invention.

FIG. 7 is an explanatory diagram of a superconducting conductor used for a high-temperature superconducting coil of a high-temperature superconducting magnet according to a seventh embodiment of the present invention.

FIG. 8 is an explanatory view of a superconducting conductor used for a high-temperature superconducting coil of a high-temperature superconducting magnet according to an eighth embodiment of the present invention.

FIG. 9 is an explanatory diagram of a superconducting conductor used for a high-temperature superconducting coil of a high-temperature superconducting magnet according to a ninth embodiment of the present invention.

FIG. 10 is an explanatory diagram of a high-temperature superconducting magnet according to a tenth embodiment of the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 superconducting conductor 2 pure silver matrix wire 3 silver alloy matrix wire 4 high temperature superconducting coil 5 reinforcing material 6
Insulation coating 7 High thermal conductive material 8 Shield plate 9 High thermal conductive tape material 10 Insulating material 11 High thermal conductive material 12 High temperature superconducting current lead 13 Superconducting conductor 14 Parallel conductor 15 Metal reinforcing conductor 16 Resin
17 impregnating material 18 refrigerator 19 heat transfer member 20
Vacuum container

Claims (20)

[Claims] 1. A high-temperature superconducting magnet having a high-temperature superconducting coil formed by winding a superconducting conductor formed of a plurality of tape-shaped high-temperature superconducting wires, wherein the high-temperature superconducting coil comprises a pure silver matrix high-temperature superconducting wire and a silver alloy. A high-temperature superconducting magnet formed using the superconducting conductor in which high-temperature superconducting wires of a matrix are mixed. 2. The superconducting conductor located at an outer peripheral portion of a cross section of the high-temperature superconducting coil, as compared with an internal superconducting conductor.
The high-temperature superconducting magnet according to claim 1, wherein the proportion of the high-temperature superconducting wire in the silver alloy matrix is increased. 3. The high-temperature superconductor according to claim 1, wherein a high-temperature superconducting wire of a silver alloy matrix having an insulating coating is used as at least one wire located at an end of the superconducting conductor. magnet. 4. The high-temperature superconducting magnet according to claim 1, wherein at least one wire of the high-temperature superconducting wire of the superconducting conductor is formed by co-winding a high thermal conductive material. 5. The high temperature superconducting magnet according to claim 4, wherein said high thermal conductive material is alumina dispersion strengthened steel. 6. When the high-temperature superconducting coil is used at a temperature of 20 K or more, aluminum or an alloy thereof is used as the high thermal conductive material, and when the high-temperature superconducting coil is used at a temperature of 35 K or more. 5. The high-temperature superconducting magnet according to claim 4, wherein copper or an alloy thereof is used. 7. A pancake-shaped disk, wherein a shield plate disposed around the high-temperature superconducting coil is formed by winding a tape material of a high thermal conductor on a surface from which magnetic flux is released with an insulating material disposed between turns thereof. 2. The high-temperature superconducting magnet according to claim 1, wherein the high-temperature superconducting magnet is formed in a solenoid type cylinder and is formed by arranging a high thermal conductor in a direction crossing the turns. 3. 8. A superconducting conductor for connecting the high-temperature superconducting coil and the high-temperature superconducting current lead is a superconducting stranded wire having flexibility or a parallel conductor electrically joined in the longitudinal direction, and is arranged in parallel with this. The high-temperature superconducting magnet according to claim 1, wherein the high-temperature superconducting magnet is formed by a metal reinforcing conductor formed. 9. The high-temperature superconducting magnet according to claim 1, wherein the reinforcing material of the superconducting conductor wound together with the high-temperature superconducting wire is a metal tape having at least one side edge portion having a round shape. . 10. The reinforcing material of the superconducting conductor wound together with the high-temperature superconducting wire is formed by stacking two or more insulating reinforcing tapes having at least a smooth facing surface and a round edge. The high temperature superconducting magnet according to claim 1, wherein the magnet is formed. 11. The high-temperature superconducting magnet according to claim 1, wherein the superconducting conductor is formed by winding glass fiber, carbon fiber, or a fiber reinforced plastic thereof in parallel with the high-temperature superconducting wire. . 12. The reinforcing material of the superconducting conductor wound together with the high-temperature superconducting wire has a linear expansion coefficient from room temperature to the operating temperature of the high-temperature superconducting coil which is larger than that of the high-temperature superconducting wire. The high-temperature superconducting magnet according to claim 1. 13. The high-temperature superconducting material according to claim 1, wherein the impregnating material impregnated between the high-temperature superconducting wires has a larger coefficient of linear expansion from room temperature to a coil operating temperature than that of the high-temperature superconducting wire. magnet. 14. The high-temperature superconducting magnet according to claim 1, wherein the reinforcing material for the superconducting conductor wound together with the high-temperature superconducting wire has a tensile stress greater than that of the high-temperature superconducting wire. . 15. The high-temperature superconducting magnet according to claim 1, wherein the reinforcing material of the superconducting conductor wound together with the high-temperature superconducting wire is wound outside the high-temperature superconducting conductor. 16. The high-temperature superconducting magnet according to claim 1, wherein the high-temperature superconducting conductor is formed by joining a metal tape or a ceramic tape having a higher strength than the wire to one surface of the high-temperature superconducting wire. . 17. The high-temperature superconducting magnet according to claim 16, wherein a high-strength tape is wound around the high-temperature superconducting conductor. 18. A high-temperature superconducting magnet having a high-temperature superconducting coil formed by winding a plurality of high-temperature superconducting wires insulated and in parallel with each other, wherein the inductance of each element wire of the high-temperature superconducting wires provided in parallel is A high-temperature superconducting magnet, wherein each element wire is electrically short-circuited at an equal position. 19. A high-temperature superconducting magnet having a high-temperature superconducting coil formed by winding a plurality of high-temperature superconducting wires in parallel and impregnating the impregnating material in the longitudinal direction between the high-temperature superconducting wires provided in parallel. A high-temperature superconducting magnet, wherein a metal powder having high electric conductivity is added to the impregnating material. 20. A high-temperature superconducting magnet for cooling a high-temperature superconducting coil from a low-heat source of a refrigerator via a heat-transfer member, wherein a temperature at which a material having a maximum thermal resistance among the heat-transfer members has a maximum thermal conductivity. A high-temperature superconducting magnet, wherein the temperature of the low heat source is lower than that of the high-temperature superconducting magnet.