JP2002231524A - Compound superconducting coil by react & wind method and method for producing the same - Google Patents

Abstract

(57) [Summary] [PROBLEMS] In a conventional compound superconducting coil by the R & W method, the electrode is not directly molded integrally on the upper or lower surface of the coil. Breakage occurred here due to deterioration due to thermal expansion, heat shrinkage, distortion due to electromagnetic force, or deterioration due to work mistakes and the like. SOLUTION: An electrode is a resin-impregnated coil in which an electrode is directly and integrally molded on a coil upper surface or the like, and a bending strain of less than 1% when a compound wire at a coil end is fixed so as not to deteriorate at the electrode portion. Was used. Further, in order to increase the mounting strength of the electrode itself, a concave portion for filling the electrode with resin was formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compound superconducting coil wound by using a heat-treated compound superconducting wire.

[0002]

2. Description of the Related Art FIG.
FIG. 2 is a cross-sectional view showing an electrode (terminal) in a conventional Nb3Sn superconducting coil 31 disclosed in Japanese Patent Application Publication No. H10-110,026. In FIG. 5, 16 is a terminal assembly attached to the upper surface 17 of the Nb3Sn superconducting coil 31 main body, 18, 20, and 27 are Nb3Sn superconducting wires before heat treatment, and 19 is a terminal assembly 1
6, 21 is a column provided on the terminal board 19, 22 is an external lead, 23 is a terminal board 1
Reference numeral 9 denotes a bonding surface to the main coil 31;
Inside, a hole through which a conductor penetrates, 25 is an adhesive used for joining the terminal board 19 to the main coil 31, and 26 is a lower peripheral portion of the terminal board.

Next, the operation will be described. Heat-treated Nb3Sn wire is brittle and its superconducting properties, especially critical current (Ic) properties, deteriorate due to bending strain and tensile strain.
n The method of manufacturing a superconducting coil includes a Nb3Sn superconducting wire that is heat-treated and then wound while controlling strain, and a Nb3Sn before heat treatment.
The superconducting wire is manufactured by one of two types of a wind & react method (hereinafter referred to as a W & R method) in which a superconducting wire is previously wound into a coil shape and then heat-treated.

[0004] In this Japanese Patent Publication No. 3-503103,
The latter manufacturing method (W & R method) is adopted for manufacturing the Nb3Sn superconducting coil. The Nb3Sn superconducting wire 20 before heat treatment is passed through a hole 24 in the terminal board 19 adhered to the main body of the coil 31, a conductor 27 is wound around and fixed to the support 21 on the upper part thereof, and then heat treated to produce Nb3Sn. A coil structure or an electrode structure for making electrical connection later prevents harmful strain from being applied to a lead portion or a terminal portion of the coil end by a brittle Nb3Sn wire.

On the other hand, in a general Nb3Sn superconducting coil produced by the former manufacturing method (R & W method), electrodes are attached to the upper or lower surface of the coil, but are generally molded integrally with the coil body. It does not have a resin-impregnated coil structure.

[0006]

In the above-described Nb3Sn superconducting coil 31, the Nb3Sn superconducting wire before heat treatment is passed through a hole of a terminal stand adhered to the coil body, and a wire is wound around a support above the Nb3Sn superconducting wire. Nb3S
n is produced by the so-called W & R method,
R & W coiled using heat-treated brittle Nb3Sn wire
If the Nb3Sn wire is passed through the hole of the terminal base (corresponding to the Nb3Sn superconducting wire 20 in FIG. 5), or the wire is wound around and fixed to a support above the wire (FIG. 5). (Corresponding to Nb3Sn superconducting wire 27)
There is a problem that the filament of the heat-treated Nb3Sn superconducting wire is broken due to bending strain and the current stops flowing, and in the worst case, the wire is broken.

Further, general Nb3 generated by the R & W method
The Sn superconducting coil does not have a resin-impregnated coil structure in which the electrodes are directly molded on the upper or lower surface of the coil, so the Nb3Sn superconducting coil extends from the electrodes to the coil body through holes etc. The line part is usually 30 ~
There is about 45 mm (when the thickness of the bobbin is about 5 mm, this distance becomes longer as the thickness increases), and thermal expansion, thermal contraction, and deterioration due to distortion due to electromagnetic force in this part, Further, there is a problem that deterioration due to human error is likely to occur in a portion exposed to the outside from the electrode to the bobbin, and in the worst case, there is a problem that the wire is broken here and cannot be used as a coil.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is intended that a compound-based wire extending from an electrode to a coil main body through a hole or the like provided in a winding frame to a coil body. It is an object of the present invention to obtain a compound-based superconducting coil having a structure that does not cause deterioration due to distortion due to electromagnetic force or electromagnetic force, and further does not deteriorate due to human error.

[0009]

According to the present invention, a method for manufacturing a superconducting coil and a compound-based superconducting coil by the R & W method is to form a compound-based wire rod extending from an electrode through a hole or the like provided in a winding frame to a coil portion. In order to avoid deterioration due to distortion due to thermal expansion, electromagnetic force, etc. in parts, and further deterioration due to human error, install an electrode in the inside of the flange of the reel in advance, and then form a plane with this traveled electrode A coil is formed from a material, and a compound-based superconducting wire that has been subjected to a heat treatment and an insulation treatment is wound around the coil, and bending strain (the wire diameter is divided by the bending diameter when fixing the compound wire at both ends of the coil portion) Value) is less than 1%, and after the electrical connection is performed, the coil is impregnated with resin, and the electrode integrated with the coil is detached from the flange of the winding frame. Reel and space It is made of the step of removing also Sir material.

In order to increase the mounting strength of the electrode molded integrally with the coil portion, an electrode having a structure in which a concave portion is formed in the electrode and resin is filled in this portion is adopted.

Further, the method for producing a superconducting coil and a compound-based superconducting coil by the R & W method according to the present invention uses an electrode partly formed into a thin plate to further increase the adhesive strength between the coil portion and the electrode. At least one side of the thin plate portion is wound with a compound superconducting wire that has been heat-treated and insulated, and the electrode is sandwiched and fixed between the layers of the coil. Then, the wire is wound, and the wire at both ends of the coil is bent. After the electrical connection is made along the electrodes with a curvature of less than 1%, the coil portion is impregnated with resin, and in some cases, the winding frame is also removed.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 shows Nb3Sn by the R & W method according to the first embodiment for carrying out the present invention.
FIG. 3 is a diagram for explaining the superconducting coil 1, more specifically, a cross-sectional view of a resin-impregnated Nb3Sn superconducting coil 1 having a structure in which electrodes are directly and integrally molded on the upper surface of the coil.

In FIG. 1, reference numeral 2 denotes a coil portion obtained by winding a formal-insulated heat-treated Nb3Sn superconducting wire (wire diameter 0.8 mm) 2a. Reference numeral 3 denotes a copper electrode connected to both ends of the coil portion 2, and 4 denotes an electrode 3 and the coil portion 2 of the superconducting wire.
PET paper (0.1m thick) to ensure insulation from
m), 5 is a stainless steel wire (S
It is a winding part of US304, wire diameter 1mm). Reference numeral 6 denotes a copper member provided to support the coil unit 2 from the outside. In the case of a conduction cooling type Nb3Sn superconducting coil, the coil unit 2 is indirectly cooled via this member. Reference numerals 7 and 8 denote spacer materials made of Teflon (registered trademark) which form a plane together with the electrodes. Reference numeral 9 denotes a stainless steel core. Reference numeral 10 denotes a flange provided on the upper part of the core 9. 10 forms a bobbin of the coil portion 2.

In order to integrally mold the electrode 3 on the upper surface of the coil portion with the structure shown in FIG.
Is fixed to the inside of the flange 10 of the bobbin via a Teflon spacer member 8 with screws, and the Teflon spacer 7 forming a flat surface together with the traveled electrode 3 forms a flange surface of the bobbin. Then, the heat-treated and insulated Nb3Sn superconducting wire 2a is wound.

At the beginning and end of the winding, the insulating film of the Nb3Sn superconducting wire 2a is removed, and then fixed to the electrode 3 with screws, and an electrical connection is made by soldering. Its Nb3Sn
The bending strain when the superconducting wire 2a is attached to the electrode 3 is preferably less than 1%, as will be described later. Further, when the curvature of the bending changes, the change in the curvature is smoothed. Is preferred. As a specific structure of the electrode 3, a linear V-groove whose depth is gradually increased is provided so that the bending strain when fixing the Nb3Sn superconducting wire 2a is less than 1%. Along the way, the Nb3Sn superconducting wire 2a was fixed so as not to apply local strain and soldered.

FIG. 2 is a graph showing the relationship of the characteristic deterioration of the critical current (Ic) due to the bending strain. In this FIG.
The Ic characteristic when the bending strain is 0% is set to 1. No degradation occurred up to a bending strain of 1.0%, but a bending strain of 1.3%
In this case, the Ic deteriorated to 70%, and the bending strain was 1.56.
It was found from this experimental result that the Ic deteriorated to about half at 52%.

After the coil thus manufactured is impregnated with resin, the screw is removed to remove the electrode 3 integrated with the coil.
The Nb3Sn superconducting coil 1 was completed by removing from the flange 10 and finally applying electric wiring. Electrode 3
It is preferable to apply a release material to the screw for fixing the inside of the flange 10 in order to facilitate the removal work to be performed later.

After the Nb3Sn superconducting coil 1 was set in a cryostat and immersed in liquid helium to bring it into a superconducting state, an electricity test was performed. As a result, it was possible to energize up to 167 A at the time of the first excitation, and succeeded in energizing B = 10T (100% of the load line) without training. Further, the thermal cycle history between the room temperature and the liquid helium temperature for 20 times and the energization test in liquid helium for 30 times were performed, but no deterioration of the coil was observed.

[Comparison Test by Conventional Method] In order to compare the performance of the present Nb3Sn superconducting coil 1, an electrode is fixed to the outside of the bobbin using the same wire, and the Nb3Sn wire from the coil portion is provided on the bobbin. Nb3Sn through the hole to the electrode
An Nb3Sn coil of the same size having a wire portion was manufactured by the R & W method, and a similar energization test was performed. As a result, only 124 A corresponding to 74% of the load line could be energized even after 10 times of training. Further, when the current test in liquid helium was performed 30 times, the current value at which quench occurred was reduced from 124 A to 118 A, and about 5% characteristic deterioration was observed.

From the above results, it is possible to obtain a structure in which the electrode is directly molded integrally on the upper surface of the coil without having a part extending from the electrode to the coil portion through a hole or the like provided on the winding frame, thereby making it possible to perform evaluation at the time of evaluation. It was confirmed that there was almost no need for training, and that current could be supplied to a predetermined characteristic, and that deterioration due to thermal expansion and distortion due to electromagnetic force and deterioration due to human error did not occur.

In the first embodiment, the Nb3Sn superconducting coil has been described as an example of the compound superconducting coil.
In addition to the above, for example, an Nb3Al superconducting coil or a high-temperature superconducting coil such as a Bi-based coil can be manufactured in the same manner as in the first embodiment to obtain the effect. Further, in the present embodiment, the direct cooling type Nb3Sn superconducting coil immersed in liquid helium has been described. However, a conduction cooling type coil using a GM refrigerator or the like may be used, as in the first embodiment. Has the effect.

In this embodiment, the coil was finished without removing the winding frame and the spacer material from the coil portion impregnated with the resin. However, after the resin impregnation, the coil was finished by removing the winding frame and the spacer material from the coil portion. The same effect as in the first embodiment can be obtained.

Embodiment 2 FIG. FIG. 3 shows a second embodiment for carrying out the present invention. FIG. 3 shows only the electrode 3A, which is an alternative to the electrode 3 of FIG. Reference numeral 13 denotes a screw hole for fixing the electrode 3A to the flange 10 of the winding frame. Reference numeral 14 denotes a V groove provided in the electrode 3A for guiding the Nb3Sn superconducting wire 2a. As the shape of the V-groove 14, a straight groove that gradually increases in depth from the right to the left in FIG. 3 so that the bending strain when the Nb3Sn superconducting wire 2a is fixed is less than 1%. Has become. 1
Reference numerals 2 and 12a denote fasteners and fixing screws for fixing the Nb3Sn superconducting wire 2a located in the V-groove 14.

The above configuration is the same as that of the electrode 3 of FIG. 1, but this electrode 3A is provided with three screw holes 11 with M4 taps as recesses, and this electrode 3A is impregnated with resin. When molded integrally with the coil portion, the concave portion is filled with resin, thereby increasing the mounting strength of the electrode 3A itself. The coil was manufactured in the same manner as in the first embodiment.

In order to quantitatively evaluate the mounting strength of the electrode 3A shown in FIG. 3, a tensile test was performed in a direction perpendicular to the connection surface and in a direction parallel to the shearing force. In contrast to the peeling at 5.5 kg and the load of 13.3 kg, none of the present electrode 3A peeled even at the load of 50 kg, and it was confirmed that the mounting strength was improved at least 3.8 to 9 times or more. I was able to. This improvement in the attachment strength indicates that the degree of protection of the Nb3Sn superconducting wire 2a of the coil portion against various stresses applied to the electrode portion of the coil has increased. It is clear that degradation is less likely to occur.

Embodiment 3 FIG. FIG. 4 shows a third embodiment for carrying out the present invention. More specifically, a thin plate portion of a part of the electrode 15 is fixed between the coil layers of the winding part 2. Nb3Sn superconducting coil 1 with structure
It is the perspective view which showed 01. In FIG. 4, the components denoted by the same reference numerals as those in FIG. 1 are the same or equivalent.

In order to integrally mold a part of the electrode 15 having a thin plate shape on the upper surface of the coil portion 2 with a structure as shown in FIG. 4, it can be manufactured by the following method, for example. First, the core 9 is subjected to a release treatment so that the coil part 2 can be easily removed from the core 9 after the impregnation. Next, in order to attach the Nb3Sn superconducting wire 2a on the winding start side of the coil portion 2 to the electrode 15, after removing the PVF insulation of the Nb3Sn superconducting wire 2a, the tape was temporarily fixed inside the flange of the winding frame with tape or the like. The Nb3Sn superconducting wire 2a is wound first on the winding core 9 until the winding core 9 has less than two layers, more specifically, a state in which a part of the electrode 15 is left unwound by the width of the thin plate portion.

Next, the electrode 15 (width 20 mm × length 100 mm)
× 0.2 mm thick) on this unrolled part and then Nb3
By winding the Sn superconducting wire 2a, the first layer of the coil and the
It is fixed while being sandwiched between the layers over a depth of less than 20 mm. When the thickness of the electrode 15 is large and a bending strain is applied to the wire, it is preferable to insert a spacer material such as PET having the same thickness as the thin plate portion of the electrode 15 between the layers other than the electrode 15. It should be noted that, for the portion of the electrode that is traveling outside the coil, the portion of the core 9 may be cut out in advance to make a relief. Further, in the present embodiment, the electrode 15 on the winding start side is fixed by being sandwiched between the first and second layers of the coil portion 2. However, the winding core 9 on which the first layer of the coil portion 2 and the insulating sheet are wound is fixed. Needless to say, the same effect can be obtained even if the fixing is performed by sandwiching between them.

After the electrode 15 is fixed in this manner, the insulating film of the Nb3Sn superconducting wire 2a of the coil portion 2 is removed, and then this fixed end is bent at a curvature such that the bending strain is less than 1%. 15 and electrical connection by soldering was performed. In order to guide the Nb3Sn superconducting wire 2a, the electrode 15 may be provided with a V-groove which is gradually separated from the coil so that the bending strain is less than 1%. The attachment process becomes easy. Thereafter, the Nb3Sn superconducting wire 2a is continuously wound,
After winding to the other end of the coil, the process ends.

Next, also at the end of the winding of the coil portion 2, the Nb3Sn superconducting wire 2a is temporarily fixed to the flange 10 of the winding frame with tape or the like, and the electrode 15 having the same structure is placed on the outermost layer of the coil. Further, by applying a winding portion 4 of stainless steel wire (SUS304, wire diameter 1 mm) to reinforce the electromagnetic force on the outside thereof, the electrode 15 is sandwiched and fixed, and the terminal portion of the coil portion 2 is also the same as above. The same processing was performed to make electrical connection with the fixed electrode 15. In this embodiment, the electrode 15 on the winding end side is fixed by sandwiching it between the outermost layer of the coil and the first layer of the stainless wire.
It is needless to say that the same effect can be obtained even if it is fixed by being sandwiched between the outermost layer and the immediately preceding layer.

After impregnating the coil portion 2 with a resin, the core 9 is released from the coil, and finally, electric wiring is applied to complete the present Nb3Sn superconducting coil 101. This N
After setting the b3Sn superconducting coil 101 in a cryostat and immersing it in liquid helium to bring it into a superconducting state, an energization test was performed. As a result, at the time of the first excitation, as in the case of the first embodiment, it was possible to energize up to 167A, and succeeded in energizing B = 10T (100% of the load line) without training. Also, 20
The thermal cycle history between the room temperature and the liquid helium temperature for 30 times and the energization test in liquid helium for 30 times were performed, but no deterioration of the coil was observed.

In order to quantitatively evaluate the mounting strength of the electrode 15 to the coil portion 2, the electrode 15 was pulled in a direction perpendicular to the bonding surface and in a direction parallel to the shearing force. No peeling was observed even with the load of, and it was confirmed that the mounting strength was improved in Examples 1 and 2 or more. This improvement in mounting strength
This indicates that the degree of protection of the Nb3Sn superconducting wire at the coil end has been increased against various stresses applied to the electrode part of the coil, and the use of this method has made coil deterioration more unlikely. .

In this example, the method of supporting the coil unit 2 is as follows.
For example, a method is used in which the lower surface and the upper surface of the coil portion 2 are sandwiched between insulating plates such as GFRP and fixed by bolts and received, but a copper member or the like is provided outside the coil portion 2 to support the coil portion 2.
(See FIG. 1) may be integrally provided by a mold, and the member may be screwed with a bolt or the like via this member, or may be supported by bonding or welding.

In the third embodiment, the direct cooling type Nb3Sn coil immersed in liquid helium has been described. However, a conduction cooling type coil using a GM refrigerator or the like may be used. There is an effect similar to that of the third embodiment.

In this embodiment, the coil and the spacer are removed from the resin-impregnated coil portion 2 to finish the coil. However, after the resin is impregnated, the coil is finished without removing the coil and the spacer from the coil portion 2. The same effect as in the third embodiment can be obtained.

[0036]

As described above, according to the present invention, an electrode and a coil portion are integrally formed, and a compound wire extending from an electrode through a hole or the like provided in a winding frame to a coil body is formed. Since the portion is eliminated and the bending strain applied to the wire at the electrode portion is controlled, there is an effect that deterioration due to thermal expansion and distortion due to electromagnetic force at this portion and deterioration due to human error do not occur.

In addition, since a screw hole is formed in the electrode to be integrally molded and the resin is filled in this portion, the adhesive strength of the electrode is increased and the electrode is not separated from the coil.

Further, in this invention, at least one side of the thin plate portion is sandwiched and fixed by a heat-treated and insulated compound superconducting wire using an electrode having a partially thin plate shape, and is impregnated with a resin. Therefore, there is an effect that the bonding strength between the coil and the electrode is further increased and the coil is not separated, and an effect that the structure near the electrode portion is simplified. In addition, although it is an incidental effect, in some cases, the winding frame can be removed from the coil and used, so that the effect that the bore diameter of the coil can be increased and the effect of reducing the number of trainings during coil evaluation can be obtained. .

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an Nb3Sn coil according to an R & W method according to a first embodiment;

FIG. 2 is a graph showing how the Ic characteristic is degraded due to bending strain in the electrode unit according to the first embodiment.

FIG. 3 is a diagram for explaining electrodes used in an Nb3Sn coil according to the R & W method of the second embodiment.

FIG. 4 is a diagram for explaining electrodes used in an Nb3Sn coil according to the R & W method of the third embodiment.

FIG. 5 is a view for explaining an Nb3Sn coil according to a conventional embodiment.

[Explanation of symbols]

1,101 Nb3Sn superconducting coil, 2a Formal-insulated heat-treated Nb3Sn superconducting wire, 2, coil part, 3,
3A Copper electrode, 4 PET paper, 5 stainless steel wire winding, 6 Copper member, 7,8 Teflon spacer material, 9 winding core, 10 Upper flange, 11 Screw holes at 3 taps, 12 fastener, 12a fixing screw, 13 screw hole for fixing the electrode to the flange of the reel, 14 V-groove provided in the electrode for guiding the wire rod, 1
5 Partially thin electrode

Claims (8)

[Claims] 1. A coil portion formed by winding a compound-based superconducting wire that has been subjected to heat treatment and insulation treatment, and electrodes connected to both ends of the coil portion. The electrodes are integrally formed with the coil portion by resin impregnation. A compound superconducting coil by the React & Wind method. 2. The compound superconducting coil according to claim 1, wherein a concave portion is formed in the electrode. 3. A step of: (a) providing an electrode in advance on a flange of the bobbin and then providing a spacer material forming a plane together with the electrode to complete the flange; (b) a bobbin including the flange A step of winding a compound-based superconducting wire that has been subjected to heat treatment and insulation treatment to obtain a coil portion, and (c) adjusting the bending strain when the compound-based superconducting wire at both ends of the coil portion is attached to the electrode to be less than 1%. (D) a step of impregnating the coil with resin, and (e) a step of removing the electrode integrated with the coil by resin impregnation from the flange of the reel. Method for manufacturing compound superconducting coil by & wind method. 4. A step of: (a) providing an electrode in advance on a flange of a bobbin and then providing a spacer material forming a plane together with the electrode to complete the flange; (b) a bobbin including the flange A step of winding a compound-based superconducting wire that has been subjected to heat treatment and insulation treatment to obtain a coil portion, and (c) adjusting the bending strain when the compound-based superconducting wire at both ends of the coil portion is attached to the electrode to be less than 1%. Setting and electrical connection, (d) a step of impregnating the coil portion with a resin, and (e) a step of removing a bobbin and a spacer material from the coil portion impregnated with the resin by a reactor and wind method. A method for producing a compound superconducting coil. 5. The method for producing a compound superconducting coil according to claim 3, wherein a concave portion is formed in the electrode integrated with the coil portion by resin impregnation. 6. A coil part formed by winding a heat-treated and insulated compound superconducting wire, and a thin plate electrode partially sandwiched and fixed between layers of the coil part. A compound-based superconducting coil by a react & wind method, wherein a winding end is electrically connected to the electrode. 7. The method for manufacturing a superconducting coil according to claim 6, wherein (a) in the step of forming a coil portion by winding a compound-based superconducting wire that has been subjected to heat treatment and insulation treatment, a part thereof is formed into a thin plate. Fixing at least one side of the thin plate portion of the resulting electrode between the layers of the coil portion; (b) removing the compound superconducting insulating film at both ends of the coil portion, and the bending strain at this end portion is less than 1% And (c) a method of manufacturing a compound superconducting coil by a reactor and wind method, comprising the steps of: impregnating the coil portion with a resin; . 8. The method for manufacturing a superconducting coil according to claim 6, wherein (a) in the step of forming a coil portion by winding the compound-based superconducting wire which has been subjected to heat treatment and insulation treatment, a part thereof is formed into a thin plate. Fixing at least one side of the thin plate portion of the resulting electrode between the layers of the coil portion; (b) removing the compound superconducting insulating film at both ends of the coil portion, and the bending strain at this end portion is less than 1% (C) a step of impregnating the coil portion with a resin (d) removing a bobbin from the resin-impregnated coil portion A method of manufacturing a compound superconducting coil by a react & wind method comprising a process.