JPH0567516A - Manufacture of superconducting coil - Google Patents

Abstract

PURPOSE:To suppress the occurrence of temperature rises in a superconducting coil by improving the heat conduction in the coil. CONSTITUTION:In this manufacturing method of such a superconducting coil that the first insulation-to-the-earth layer 2, a coil 3 composed of a superconducting conductor, and the second insulation-to-the-earth layer 4 are closely arranged on the internal surface side of a cylindrical cooling body 1 that becomes an outer bobbin in a state where hey are integrally fixed to each other and an inner plate 5 is provided so as to cover the layer 4 side surface, the coil 3 is formed by winding the superconducting conductor around the inner plate 5 with the layer 4 in between after the plate 5 is put around a temporary bobbin 6. Then, after the cooling body 1 is put on the coil 3 with the layer 2 in between, the inner plate, coil, and the first and second insulation-to-the-earth layers are integrally fixed to each other by impregnating them with a resin. Then this superconducting coil is obtained by removing the temporary bobbin 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a superconducting coil which can enhance heat conduction inside the coil.

[0002]

2. Description of the Related Art In a superconducting magnet for particle measurement in the field of high energy physics, a superconducting coil was placed in a vacuum and separately installed in consideration of being used in weightless conditions such as outer space. The structure in which the coil is indirectly cooled by the action of solid heat conduction from a refrigerant container, a cooling pipe, or the like is adopted. Most of these are relatively large in diameter and length of 1 m or more.

By the way, when the temperature difference between the superconducting coil and the refrigerant container, the cooling pipe, etc. (hereinafter referred to as the cooling body) becomes significantly large due to the radiant heat from the outside of the vacuum, the superconducting coil must maintain the required performance. I can't. Also,
If the superconducting coil is disturbed from the outside and the quench phenomenon occurs, it is necessary to prevent the coil from burning due to the concentration of energy in the coil. There is a need. These are basically necessary items for operating the superconducting coil to protect the integrity of the coil.

In general, between the superconducting coil for indirect cooling and the cooling body, solid heat conduction acts by mutual adhesion of the cooling body and the superconducting wire made of metal such as aluminum and the insulating material interposed therebetween. The composition is adopted. The cooling body is usually integrated with a structure that supports the coil against the strong electromagnetic force that normally acts on the superconducting coil. However, the superconducting coil is often subjected to severe cooling and heating cycles, electromagnetic force, and mechanical force, and there is a possibility that local peeling or the like may occur between the coil and the cooling body.

Therefore, an inner plate made of a divided metal plate is attached to the inner surface of the coil to form a heat conduction path separate from the cooling body in the winding direction of the coil, and the temperature of the entire coil is increased. It is known that the film is formed so as to be held uniformly.

FIG. 5 is a side view of a conventional inner winding superconducting coil having an inner plate. In the figure, 1 is a cooling body made of a metal cylinder having good heat conductivity as an outer winding frame, 2 is a first ground insulating layer attached to the inner surface side of the cooling body 1, and 3 is an insulated superconducting wire. The coils 4 which are rotated and fixed to each other are adhered to the inner peripheral surface of the second ground insulating layer 4 by an adhesive. It is an inner plate.

As shown in the figure, the inner plate 5 is formed of a rectangular plate which is divided into a plurality of parts in the circumferential direction in order to form an electric circuit that links the coil 3 in the same direction as the coil 3 and to prevent heat generation due to inductive loss. It is configured. Further, the inner plate 5 is usually made of high-purity aluminum of 99.999% or more in order to obtain the maximum heat conduction characteristics in a state where it is cooled to a cryogenic temperature together with the superconducting coil. Further, one of the purposes of the inner plate is to quickly quench the entire coil without generating a local high temperature portion in the coil, and the inner plate itself should not have an excessive heat capacity. From these conditions, the inner plate is usually a thin plate of 1 mm or less,
The material has very soft properties.

[0008]

However, in order to manufacture the superconducting coil having such a structure, in the step of applying the above-mentioned inner plate to the second ground insulating layer 4,
Since there are work such as bending for coil curvature, application of adhesive, fixing of inner plate, and curing of adhesive, 1
It is extremely difficult to construct a rectangular plate extending up to m or more without deforming it and without causing a slight gap. For this reason, not only the working time becomes long and uneconomical, but there is also a possibility that the required heat transfer effect cannot be obtained in the inner plate. It is an object of the present invention to provide a method for manufacturing a superconducting coil that can increase heat conduction inside the coil and suppress a temperature rise to a low level.

[0009]

In order to achieve the above object, the present invention provides a first ground insulating layer and a superconducting wire which are closely arranged on the inner surface side of a cylindrical cooling body which is an outer winding frame. In the method for manufacturing a superconducting coil, the coil and the second ground insulating layer are integrally fixed, and an inner plate is attached so as to cover the surface on the second ground insulating layer side.
Before winding the coil, an inner plate is arranged on the outer periphery of the temporary winding frame, and the superconducting wire is externally wound via the second ground insulating layer to form a coil. Then, the outer peripheral side of the coil is formed. After fitting the cooling body through the first ground insulating layer, the inner plate, the coil, and the first and second ground insulating layers are impregnated with resin to fix them integrally, and thereafter, the The temporary winding frame is removed to obtain a superconducting coil.

Further, according to the present invention, in a method of manufacturing a superconducting coil in which a superconducting wire is wound in multiple layers around a solenoid winding and impregnated with a resin, the superconducting wire is sandwiched between winding layers by a metal strip having a high thermal conductivity. A superconducting coil is obtained by winding the metal strip sandwiched between other layers so as to be continuous with each other, and then impregnating them with a resin and integrally fixing them.

[0011]

According to such a method of manufacturing a superconducting coil,
By applying an inner plate on the outer circumference of the temporary bobbin and winding the superconducting wire externally, a uniform surface pressure is applied to the inner plate arranged on the outer peripheral side of the temporary bobbin by the tension of the coil. If the resin is impregnated in this state, the inner plate will adhere to the coil with almost no gap when impregnated with the resin. Therefore, in the superconducting coil obtained by such a manufacturing method, the coil, the second ground insulating layer, and the inner plate can be brought into a state in which good solid heat conduction is performed with each other.

Further, in the method for manufacturing a multi-layer superconducting coil, a metal strip having a large thermal conductivity is sandwiched between the winding layers of the superconducting wire wound by the solenoid, and a metal strip is sandwiched between other winding layers. The superconducting wire is wound while being sequentially joined to the strip, and these are integrally fixed by resin impregnation so as to obtain a multilayer superconducting coil.Therefore, when a part of the coil is quenched, heat is generated in the insulating layer. At the same time, it is transmitted to the adjacent conductor via the metal strip, and the heat is rapidly transferred to other layers. Therefore, since the propagation of quench can be accelerated, it is possible to suppress the temperature rise at the time of heat generation.

[0013]

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

FIG. 1 is a side sectional view showing a first embodiment for explaining a method of manufacturing a superconducting coil according to the present invention. In the figure, a cooling body 1 serving as an outer winding frame has a function of supporting an electromagnetic force of a coil, and a first ground insulating layer 2 and an insulated superconducting conductor are wound around an inner peripheral side of the cooling body 1. The superconducting coil is constructed by sequentially disposing the coil 3, the second ground insulating layer 4, and the inner plate 5 which are fixed to each other in the same manner as in the conventional case. Is manufactured as follows.

That is, in this embodiment, the inner plate 5 is temporarily fixed on the outer peripheral surface of the temporary winding frame 6 having a diameter smaller than that of the cooling body 1, and the second ground insulating layer 4 is formed on the outer peripheral surface thereof. Then, coil the superconducting wire by winding it with appropriate tension.
And the first ground insulating layer 2 is further formed on the outer peripheral surface of the coil 3, and then the cooling body 1 is first fitted by means such as shrink fitting.
Assemble by closely adhering to the ground insulating layer 2. Therefore, the inner plate 5 is temporarily fixed by using the temporary winding frame 6, and the superconducting wire is externally wound on the outer peripheral side thereof, so that a uniform pressing force acts on the entire coil.

Next, by injecting epoxy resin into each of the members assembled in this way as an integral body and performing vacuum impregnation, the cooling body 1, the first ground insulating layer 2, the coil 3, and the second ground insulating layer are formed. 4 and the temporary winding frame 6 are fixed to each other with a very small gap. After that, the temporary winding frame 6 is removed to obtain the superconducting coil. In this case, the temporary winding frame 6 is divided into a plurality of parts so that they can be easily removed, and a strong one is used by assembling them.

In the superconducting coil obtained by such a manufacturing method, all the members are integrally vacuum-impregnated so that solid heat transfer acts. In particular, the inner plate 5 is a member whose main purpose is to conduct heat using a high-purity aluminum material, and the inner plate 5 can be adhered with almost no gaps. There is almost no fear that the inner plate 5 will not adhere to the coil surface due to bending or folding.

Therefore, the work of adhering the inner plate 5 to the inner peripheral surface of the coil 3 is extremely simple, and the heat transfer between the inner plate 5 and the coil 3 is excellent, so that the entire coil is always uniform. It is cooled and can keep the function of preventing quenching well. Further, even when the coil is quenched by external disturbance, the local high temperature part is relaxed and the energy is quickly diffused throughout the coil, so that the coil is not damaged and the reliability is improved. it can.

FIG. 2 is a sectional view showing a second embodiment of a superconducting coil to which the method of the present invention is applied, and the same parts as those in FIG. 1 are designated by the same symbols. In the present embodiment, the superconducting coil is a single-layer winding, and even with the superconducting coil having such a configuration, the inner plate 5, the second ground insulating layer 4, and the superconducting wire are single-layer winding on the outer peripheral side of the temporary winding frame 6. The coil 3 and the first ground insulating layer 2 are sequentially arranged and assembled, and the inner plate 5 is assembled by the same method as in the first embodiment.
By closely contacting the coil 3 with the coil 3, it is possible to obtain the same effect as that of the above-described embodiment.

As described above, according to the manufacturing method of the superconducting coil described in the first and second embodiments, the inner plate 5
The adhesion between the coil 3 and the coil 3 becomes extremely good, and as a result, the cooling action during steady operation, which is the function of the inner plate 5, is the length of the coil for indirect cooling,
Even with a relatively large coil whose diameter exceeds 1 m, the temperature distribution is suppressed to a temperature difference of about 0.5 ° K at most, and even if the temperature rises locally during quenching, the entire coil is quickly soaked, The equalizer function that promotes quench propagation is also dramatically improved compared to the work method of attaching the inner plate after the coil is formed and fixed. Therefore, the superconducting coil has high quenching prevention performance and can prevent damage to the coil even if it is quenched, so that the superconducting coil can be made highly reliable.

The above is the solution from the viewpoint of the adhesion between the inner plate 5 and the coil 3, but as another factor of insufficient cooling capacity and quench protection capacity, especially when the coil has a multi-layer winding structure, When a quench occurs in the superconducting wire in the layer farthest from the cooling plate, diffusion of the normal conducting resistance portion propagates relatively fast in the longitudinal direction of the superconducting wire, but the formals and The quench propagation in the lateral direction is very slow due to the interposition of the insulating layer of epoxy resin, which has a relatively low thermal conductivity, and has been experimentally shown to be about 1/100 to 1/1000 in the longitudinal direction. For this reason,
The wire rod in the portion where the quench is first generated locally generates a large amount of heat, and is hard to be cooled due to the position away from the cooling plate, which causes a crack in the resin around the wire rod. Furthermore, when the energy stored in the coil is large, the insulating layer may be damaged or the wire material may be melted.

3 and 4 are views for explaining an embodiment of a method for manufacturing a superconducting coil according to the present invention which can improve heat conduction inside the coil. FIG. 3 is a sectional view showing a part of the superconducting coil. 4 is a front view of the same. In FIG. 3, a superconducting wire 11 is a rectangular conductor in which a stabilizer of pure aluminum is attached to a monolith conductor of NbTi and copper, and its surface is insulated by formal. When the superconducting wire 11 is solenoid-wound to form a multi-layer coil, a strip 13 of pure aluminum is arranged at right angles to the winding direction, and is sandwiched when winding the next layer. The aluminum strip 13 is made by rolling high-purity aluminum into a thickness of about 0.25 mm, and has a width of about 1/50 to 1/60 of the circumference of the coil 12, and the width of the strip is the same as the width of the strip in the circumferential direction of the coil. Place intermittently with equal or more intervals.

The aluminum strip 13 is continuously folded back to the upper layer through the winding of two layers on the upper layer thus arranged, and is sandwiched between the layers of the winding of the next layer. in this case,
As shown in FIG. 4, the aluminum strips 13 are arranged such that every two layers are continuously sandwiched between the layers of the windings, and the next two layers are sequentially connected with a phase difference. Reference numeral 15 is a cooling plate having a cooling function for supporting the coil 13 from the outside.

Superconducting coil 1 wound in this way
2 is integrally impregnated and fixed with an epoxy resin 16 so that the space between the superconducting wire 11, the aluminum strip 13 and the other insulating spacers 17 is completely filled and adhered to form a multilayer superconducting coil.

In the multi-layered superconducting coil obtained by such a method, the temperature rise due to local heat generation during excitation or local energy concentration at the time of quenching is caused by the heat conduction between the layers. Due to the action of the aluminum strip having a high rate, the heat transfer in the direction perpendicular to the wire, particularly between layers, becomes fast, the local temperature rise is suppressed, and the quench back function is increased.

Further, the local heat generation, for example, heat generation due to resin cracks, etc., has a high cooling capacity, and is therefore easily stabilized without quenching. In addition, one aluminum strip from one layer transfers heat to the conductor above the next two layers, but since that heat is transferred at high speed in the conductor in the wire direction (circumferential direction), it was arranged in the next phase. It is transferred to the aluminum strip, and then transferred to the conductors two layers above.

Therefore, in such a superconducting coil,
Since the aluminum strip sandwiched between the layers is made of a material cut to a size about twice the coil width, after the first layer is wound, the aluminum strip is cut until the winding of the second layer is completed. Temporary fixing can be performed relatively easily. In addition, since the high-purity aluminum strip has the property that its intended thermal conductivity is easily reduced by mechanical strain, the number of times of bending back increases,
There is a high possibility that the performance of the quench back will deteriorate. In that point, in the case of this configuration, the winding of the next layer can be performed only once by bending back.

On the other hand, since the heat propagation is very fast in the longitudinal direction of the superconducting wire, the aluminum strips are arranged intermittently in the circumferential direction and the aluminum strips between all the layers are continuous. Function is improved, and winding work can be easily performed. In addition, the inner diameter of the multilayer coil,
If the difference in outer diameter is large, the width of the aluminum strip can be changed depending on the layer to enhance the heat conduction ability. Also,
The voltage generated inside the coil may reach several kV in the event of a quench during the excitation of the superconducting coil of this configuration. However, the aluminum strip sandwiched in the coil is between the ground potential and the conductor potential. It becomes a floating potential at. However, since the aluminum strip is divided into two layers as in the above embodiment, the potential difference between the aluminum strip and the conductor can be kept small, and the amount of the insulating material can be reduced, and the coil size and weight can be reduced while the local area of the coil is reduced. A multi-layer superconducting coil with a small temperature rise can be realized.

In the above embodiment, the continuity of the aluminum strip is set to 2 as in the first to third layers and the third to fifth layers.
Although the effect is considered to be equal or higher in each layer, the same effect can be expected even if the continuity of the aluminum strip is every 3 to 5 layers. Further, although the aluminum strip having high purity is used in the above-mentioned embodiment, the same effect can be obtained even when other metal strips such as copper are used.

[0030]

As described above, according to the present invention, it is possible to provide a method of manufacturing a superconducting coil which can enhance the heat conduction inside the superconducting material and suppress the temperature rise to a low level.

[Brief description of drawings]

FIG. 1 is a sectional view of a part of a coil showing a first embodiment for explaining a method for manufacturing a superconducting coil according to the present invention.

FIG. 2 is a sectional view of a part of a coil showing a second embodiment of the present invention.

FIG. 3 is a sectional view of a part of a coil showing an embodiment for explaining a method for manufacturing a multilayer superconducting coil according to the present invention.

FIG. 4 is a front view of a part of the coil showing the embodiment.

FIG. 5 is a side sectional view for explaining a conventional method for manufacturing a superconducting coil.

[Explanation of symbols]

1 ... Cooling body that also serves as an outer frame, 2 ... First insulating layer to ground,
3 ... Coil, 4 ... Second insulating layer to ground, 5 ... Inner plate, 6 ... Temporary reel, 11 ... Superconducting wire, 12 ...
… Superconducting coil, 13 …… Aluminum strip, 15 ……
Cooling plate, 16 ... Epoxy resin, 17 ... Insulating spacer.

Claims (2)

[Claims] 1. A first ground insulating layer, a coil made of a superconducting wire, and a second ground insulating layer, which are closely arranged on the inner surface side of a cylindrical cooling body which is an outer winding frame, are integrally fixed to each other. In the method for manufacturing a superconducting coil, which comprises covering an inner plate so as to cover the surface on the side of the second ground insulating layer, an inner plate is provided on the outer periphery of the temporary winding frame before winding the coil. Then, the superconducting wire is wound around the second ground insulating layer to form a coil, and then a cooling body is fitted on the outer peripheral side of the coil through the first ground insulating layer. ,
A superconducting coil, characterized in that the inner plate, the coil, and the first and second ground insulating layers are impregnated with resin to integrally fix them, and then the temporary winding frame is removed to obtain a superconducting coil. Coil manufacturing method. 2. A method for manufacturing a superconducting coil, which comprises winding a superconducting wire in a multi-layer winding around a solenoid and impregnating with a resin,
The superconducting wire is wound while sandwiching a metal strip having a large thermal conductivity between the winding layers, and is wound while being bonded so as to be continuous with the metal strips sandwiched between the other layers, and then impregnating them with a resin. A method for manufacturing a superconducting coil, characterized in that they are integrally fixed.