JPS602726B2 - Superconducting wire and superconducting magnet using this wire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a superconducting wire and a superconducting magnet, and particularly to a superconducting wire and a superconducting magnet suitable for use in large-scale devices such as nuclear fusion reactors and energy storage devices.

A composite superconducting wire used in this type of superconducting magnet is shown in FIG.

Fig. 1 shows a cut end surface of a composite superconducting wire (hereinafter sometimes simply referred to as bran material) 1, and the wire 1 is a composite superconducting wire (hereinafter sometimes simply referred to as bran material) 1, which is made of a plurality of superconducting strands (hereinafter simply referred to as strands) 2 with a rectangular cross section. It is configured by being embedded in the substrate 3. This wire village 1 is wound into a coil so that the upper and lower medium-wide winding surfaces IA in FIG. Insulator 4
is provided to insulate each wire 1 during winding. Furthermore, when the wire 1 is wound into a coil, the coiled wire 1 is cooled by liquid helium (He), and this liquid He comes into contact with the cooling surfaces IB in the left and right spaces. . At this time, since both sides of the winding surface IA are covered with the insulator 4, it does not come into contact with the liquid He. Almost all large superconducting magnets that have been constructed using the composite superconducting wire 1 as described above are designed based on the complete stabilization method, and are used in various practical applications.

In the complete stabilization method, it has been demonstrated that the superconducting magnet can be operated stably under the conditions that the stabilization parameter Q shown by the following equation is 1 to 4. Here, p: Specific resistance of the substrate ld: Design current value of the coil ASub: Cross-sectional area of the substrate p: Circumferential length q of the cooling surface IB cooled by liquid He
: Heat flow east from cooling surface IB to liquid He.

In this stabilization method, even if the superconductivity of the superconducting wire 2 is broken, the current ld flows through the substrate 3, during which time the superconductivity is restored and the original state can be restored.

That is, in the above formula {1}, the numerator means the amount of heat generated from the substrate 3, and the denominator means the amount of heat generated by cooling the substrate 3. Therefore, designing so that Q is smaller than 1 means that the amount of cooling heat exceeds the amount of heat generated, and the cooling required for superconductivity is always satisfied. Note that the substrate 3 is usually made of a metal that has low electrical resistance at extremely low temperatures, such as high-purity copper or aluminum. 2 and 3 show a structure in which a circle-shaped superconducting coil is formed from the conventional composite superconducting wire 1 shown in FIG. 1, FIG. 2 is a front view thereof, and FIG. It is an enlarged sectional view along the town-m line of a figure.

In these figures, the D-shaped coil 5 is obtained by winding the wire strip 1 flatwise, that is, with a medium-wide winding surface IA sequentially wound in a D shape via an insulator 4 (hereinafter simply referred to as a coil or a winding layer). A plurality of winding surfaces A are sequentially arranged in the lateral direction of the winding surface A with a spacer 6 interposed therebetween. On this occasion,
The spacers 6 are formed by applying insulation to an electrical insulator or a metal piece, and are arranged at appropriate intervals to form cooling channels 7 through which liquid He flows between each coil. That is, the space surrounded between the opposing cooling surfaces IB of each wire rod 1 forming the left and right side surfaces of each coil arranged in the horizontal direction and the opposing surfaces of each spacer 6 is defined as a cooling channel 7. . This cooling channel 7 cannot sufficiently cool the cooling surface IB of the wire rod 1 unless the liquid He flows smoothly, and there is a risk that the Q of the above-mentioned stabilization method becomes larger than 1. Therefore, it is necessary to create a structure in which the anaerobic bubbles generated by the flow of liquid He and the heat generated during excitation of the superconducting magnet can escape as quickly as possible. Also, in terms of cooling effect, the side surface of each coil, that is, the cooling surface IB
The larger the exposure ratio {(area of cooling surface IB not covered by surfacer 6)/(total area of cooling surface IB)}, the better.
On the other hand, in order to support the electromagnetic force acting between each coil (between layers), the exposure rate cannot be made too large. In order to satisfy these various conditions, the shape of the spacer 6 must be devised, resulting in a complicated shape, as shown in an example in Figure 2, which requires insertion during coil winding and assembly. , since it has to be fixed, it is very time consuming and there is a problem that work efficiency is reduced. In addition, the conventional structure
However, there is also the problem of mechanical weakness.

In particular, the superconducting toroidal coil used in a nuclear fusion reactor is a gigantic device with 10 to 1 times the stored energy of the largest conventionally constructed superconducting magnet (800 MJ of stored energy), and therefore acts on the coil winding. The electromagnetic force is also an order of magnitude larger. In addition, the electromagnetic force is non-uniform because the circular or D-shaped coil 5 is arranged in a torus shape by winding around the outer circumference of a torus-shaped iron container for enclosing plasma. Furthermore, the electromagnetic force-resistant structure is not suitable for other purposes than conventional structures because bending moment and rotational torque act under the influence of the pulsed magnetic field from the poloidal coil (applied in the direction indicated by arrow P in Figures 2 and 3). The coil structure for this purpose is insufficient. An object of the present invention is to provide coil cooling liquid H without requiring a complicated arrangement of spacers.
It is an object of the present invention to provide a superconducting magnet that allows smooth flow of e and a superconducting wire that allows the superconducting magnet to be easily formed.

In order to achieve the above object, the first aspect of the present invention is that the cross section of the substrate surrounding the superconducting millet wire is approximately rectangular;
In a superconducting wire village that is spirally wound through an insulating material to form a coil, the substrate has a side surface that is perpendicular to the axis of the spirally wound coil, and a layer inside this side surface. This is a superconducting wire in which a plurality of narrower convex portions are formed intermittently along the longitudinal direction.

In addition, the second aspect of the present invention is that a superconducting wire having a substantially rectangular cross section surrounding a superconducting element wire is spirally wound through an insulating material to form a disk-like coil, which can be used as a substrate. In the superconducting magnet configured by a plurality of superconducting magnets arranged in the direction of the bag through the substrate, each of the coils has a plurality of convex portions formed on at least one side of the substrate, narrower than the inside of this side, intermittently along the longitudinal direction. The obtained superconducting material is wound in a spiral shape through the insulator by bending the surface perpendicular to the side surface on which the convex portion is formed, and winding the superconducting material in a spiral shape along the circumferential direction on the surface facing the smoother. This superconducting magnet is provided with grooves and a plurality of radial grooves that extend through these grooves.

Embodiments of the present invention will be described below based on the drawings.

Here, the same reference numerals are used for the same or equivalent components as in the conventional example. FIG. 4 is a perspective view of a part of a composite superconducting wire village 8, which is an embodiment of the superconducting wire village according to the present invention.
5 and 6 are cut end views taken along lines VV and W- in FIG. 4, respectively.

In these figures, the wire rod 8 includes a plurality of superconducting strands 2 arranged in a substantially elliptical shape and embedded in a substrate 3 formed into a vertical rectangle. Unlike the conventional example, this wire rod 8 is wound along the upper and lower middle winding surfaces 8A, so-called edgewise winding. Therefore, the insulator 4 is in close contact with one surface of this winding surface 8A, which is the lower surface in the figure. Grooves 10 are continuously formed in the upper and lower portions of both sides of the composite superconducting wire 8 along the longitudinal direction of the wire 8, and grooves 10 in the upper and lower portions are formed in the longitudinal direction of both sides of the wire 8. Speeding groove 1
A plurality of 1's and 0's are formed.

The upper and lower grooves 10 form circumferential grooves when the wire 8 is wound edgewise into a coil, and the vertical grooves 11 form radial grooves. Furthermore, the bottom surfaces of these grooves 10 and 11 are cooling surfaces 8 that are in contact with liquid He.
The convex portion 8C, which is mixed with B and is left on the side surface with these grooves 10 and 11, is brought into contact with a flat plate-shaped smoother 6, which will be described later. A cooling channel 7 is formed by this spacer 6 and the grooves 10 and 11. At this time, the convex portion 8
The length of the wire C in the longitudinal direction is h, and the length of the recess formed between these convex portions 8C, that is, the longitudinal groove 11, is i. Here, the material of the composite superconducting wire 8 will be mentioned. The superconducting wire 2 is made of an alloy containing niobium (Nb), titanium (Tj), zircon (Zr), etc., such as alloy superconductor such as Nb-Ti, Nb-Ti-Zr, or niobium (Nb). ), tin (Sn), vanadium (V), gallium (Ga), etc., ie, a compound-based superconductor such as N-based Sn and V3Ga. Substrate 3 is copper 0 (Cu), aluminum (N), Cu-Nj (nickel), Cu-Sn.
, Cu10a, Nb, Ta (tantalum) and other metals
Consists of a species or two or more species. Next, FIGS. 7 to 9 show an example in which the wire rod 8 of FIG. 4 is wound edgewise to form a D-shaped coil. The figure is an enlarged sectional view taken along the skin line in Fig. 7, and Fig. 9 is an enlarged front view with the smoother of Fig. 7 removed.

In these figures, the wire layer 8 is wound edgewise multiple times to form a unit coil (winding layer), and each of these unit coils is wound through a flat plate-shaped spacer 6 formed in a D-shape in front. A plurality of D-shaped coils 9 are arranged in the horizontal direction.Furthermore, a plurality of locations near the upper and lower ends of the spacer 6 in FIG.
It is fastened with a through bolt (not shown). The spacer 6 is made of an insulating plate or a stainless steel plate with insulation treatment on both sides. In the D-shaped coil 9 constructed in this way, a cooling channel 7 is automatically formed by the grooves 10; D
The shaped coils 9 are threaded through each other in the circumferential direction and the radial direction.

Therefore, soot bubbles generated in liquid He, which is cold soot, due to heat generation during excitation can rise through the path shown by arrow Q in FIG. 9 and escape smoothly to the outside, causing the bubbles to stagnate. It is possible to prevent the temperature increase in the coil caused by this, and further damage to the superconducting phenomenon. In addition, in the portions of the D-shaped coil 9 located on both the left and right sides in FIG. 7, the cold soot bubbles mainly rise in the grooves 10 in the circumferential direction. As mentioned above, "According to this embodiment, since the grooves 10 and 11 are formed in the wire 8," the spacer 6 can be made into one large plate shape or annular shape.
Insertion and assembly of the spacer 6 can be made much easier than in the past.

At the same time, it is possible to make the base plate 6 mechanically strong.Furthermore, the end of the base plate 6 is formed longer than the winding part, and a through bolt (not shown) can be inserted and fastened there, or a support member can be attached. (not shown) can be used to increase the mechanical strength of the entire coil, making it far superior to conventional coils in terms of electromagnetic force resistance.
In this case, as shown by chain lines (imaginary lines) in FIG. 16, which will be described later, holes 6A are formed in the baser 6 within a range that does not impair its strength, and the cooling channels T between the unit coils are interconnected. By doing so, the circulation of the refrigerant or cold soot bubbles can be further improved. Further, if the wire 8 is wound edgewise as in this embodiment, the power is applied in the direction of arrow P in FIG. 7, that is, in the direction perpendicular to the winding surface 8A. The eddy current loss caused by the magnetic pulsed magnetic field can be significantly reduced compared to conventional flat-width winding. This eddy current loss is proportional to the second to third power of the wire perpendicular to the magnetic field, and edgewise winding has a great effect. The fact that this eddy current loss can be reduced means that the overall heat generation amount of the D-shaped coil 9 can be reduced to zero, and the superconducting phenomenon can be stabilized. Furthermore, in the conventional structure where the cooling surface IB is narrower than the insulated winding surface IA, the wire size becomes unnecessarily large, which reduces the average current density more than necessary and is uneconomical. In this embodiment, this point can also be improved. Next, FIGS. 10 to 15 show different embodiments of the grooves formed in the line villages.

In FIG. 10, a plurality of grooves 12 are also formed in the winding surface 8A on the upper side of the line village 8 in FIG. It's easy to do. FIG. 11 shows the grooves 10 in the longitudinal direction of the wire rod 8
Although not shown, it may also be provided only at the upper part. Fig. 13 shows grooves 10 and i grooves provided only on the left side surface of the wire rod 8. Fig. 13 shows grooves 1Q' and lower part on one side of the wire rod 8 in the longitudinal direction (circumferential direction during winding). This lower groove IQ is also formed by diagonally cutting the lower part of the wire rod 8. This diagonal cutting makes it easy to manufacture the wire rod. Grooves 10 and 11 are formed on one side of the wire strip 8 that is wound around the wire.The grooves 10 and 11 are provided only at the top of the longitudinal groove 1, and are cut obliquely.In these cases, Since the cooling surface area decreases, it is necessary to take measures such as lowering the composite resistivity or increasing the substrate cross-sectional area in order to satisfy the complete stabilization condition for the same specifications. Fig. 15 is a wire rod 8 having a substantially rectangular cross section, with upper and lower surfaces,
Continuous annular grooves 12 and 11 are provided on the left and right sides, and a longitudinal groove 10 is provided in each corner. The groove 10 may be formed in this way or in any other shape.
, No. 1 and No. 12 may be formed using different methods, almost the same effect can be obtained. Next, FIG. 16 is a cross-sectional view of an example showing the specific structure of a wire rod suitable for use in the superconducting magnet of the present invention, and FIG. 17 is a cross-sectional view for confirming the effect of the wire shown in FIG. FIG. 3 is a cross-sectional view of a comparative example. In Figure 16,
The composite superconducting wire 14 has t in the narrow part, that is, in the lateral middle.
Vertical grooves 11 with a depth m in the longitudinal direction are formed on both sides of the steel substrate 15, which is approximately rectangular in the wide part, that is, the longitudinal center is w, and longitudinal grooves 11 are formed in the upper and lower parts of both sides of the wire rod 14 in the longitudinal direction. A groove 10 having a depth m in the direction perpendicular to the plane of the paper and having a substantially rectangular cross section is formed in the center of the copper substrate 15 in the longitudinal direction, that is, in the radial direction during winding. A multi-core wire 16 is embedded, and furthermore, aluminum substrates 17 having a substantially ten-round cross section are embedded at predetermined intervals above and below the ultra-fine multi-core wire 16Z.

A smoother 6 is brought into contact with the side surface of the wire 14, and an insulator 4 is brought into contact with the winding surface. At this time, the experiment was conducted with no noble hole 6A actually formed in the smoother 7. The steel substrate 15 is made of high-purity copper with a resistance ratio of 20, and the aluminum substrate 17 is made of high-purity aluminum with a resistance ratio of 50. The specific resistance of this copper is the magnetic flux density of 7.5 Tesla (T
), temperature 4. K' is 4.25×10-80 arc, and the specific resistance of aluminum is 1.0×10 under the same conditions.
-80 arc, and the composite resistivity of this wire substrate is 2.0×10-80. The cross-sectional lighting ratio between the copper part and the aluminum part is 2:1, and the ratio of the length of the convex part of the cooling surface (h) to the length of the convex part and the length of the concave part (h + i), h
/(h+i) was set to 0.7 (see Figure 4). Further, the ultra-fine multi-D wire 16 is composed of a large number of superconducting Qin wires and a copper substrate, and the ratio A skin/Asup of the copper cross-sectional area (Acu) to the superconducting wire cross-sectional area (Asup) is about 4. be. The other dimensions are as listed in Table 1 below, but they were calculated using the conditions in Table 1 from the above equation, assuming a design current of 10 (kA) and a design maximum magnetic field of 7.5 (T). The average value of the stabilization parameter Q is 0.86 (<1), which sufficiently satisfies the stabilization condition.
A composite superconducting wire 18 having a structure in which grooves 10 and 11 are omitted from the wire 14 having the structure shown in FIG. 6, and the wire is wound flatwise.
It shows a cross section of.

This wire rod 18 is equivalent to the conventional wire rod 1 in appearance. Next, in order to compare the wire rod 14 with the wire rod 14 of FIG. 16, the wire rod 18 of FIG.
The dimensions of each part are shown in the right column of Table 1 when the stabilization parameter Q is designed to be the same for 5T). In FIG. 17, w indicates the length of the wide side of the line 18, t indicates the length of the narrow side, and g indicates the gap between each unit coil, that is, the length of the cooling channel 7. Showing the inside. Table 1 According to Table 1 above, in order to make the stabilization parameter Q the same value, the method shown in FIG.
It can be seen that the cross-sectional area of the wire is 2.3 times that of the method shown in the figure, and the average current density including the cooling channel is 1/2.

In other words, ``The wire rod 14 shown in Fig. 16, which is provided with grooves 10 and 11 and wound edgewise, can satisfy the same specifications with a much smaller cross-sectional area than the wire rod 181 shown in Fig. 17. .

In particular, in the case of a super-large magnet, a large wire cross-section means that the entire coil becomes large, resulting in a very uneconomical design including the capacity of the refrigerator for cooling the coil. As mentioned above, in the embodiment shown in FIG. 16, since the ultra-fine multi-filament wire village 16 containing superconducting wires is concentrated in the center of the wire 14, the ultra-fine multi-filament wire 16 is concentrated during edgewise winding. The amount of deformation applied to the wire can be reduced, and breakage of ultra-fine strands can be prevented.

In other words, if the plain twill is dispersed in the height direction of the wire 14 (radial direction of winding), the radius of curvature of the plain wire located on the outer circumferential side and the plain wire located on the inner circumferential side during winding is This is because the wire rod 14 in FIG. By embedding wires, plates, tungsten wires, etc., the mechanical properties such as tensile strength and bending strength of the wire 14 can be significantly increased.

This can also be applied to the wire rod 8' in FIG. Also, groove 1
0 may be omitted, and the groove 11 may be formed after the wire 8 is wound into a coil, but in this case, the groove 11 will have a complicated shape like the conventional smoother 6, which is not practical. . As described above, according to the present invention, there is provided a superconducting magnet that allows cold butterflies and refrigerant bubbles to flow smoothly through the grooves, and that allows effective cooling even when using a spacer with a simple structure. In addition, it is possible to provide a superconducting wire that can easily form such a superconducting magnet.

[Brief explanation of drawings]

Fig. 1 is a cut end view of a conventional composite superconducting wire, Fig. 2 is a front view of a conventional O-shaped coil formed using the wire shown in Fig. Cut end view along
FIG. 4 is a partial perspective view showing an example of a composite superconducting wire used in a superconducting magnet according to the present invention, and FIGS. 5 and 6 are lines V-V and - of FIG. 4, respectively. FIG. 7 is a front view of the D-shaped coil of the present invention formed using the wire shown in FIG. 4, and FIG. 8 is an enlarged cut end view along the field line of FIG. 9 is an enlarged front view of the main part of FIG. 7 with the smoother removed, FIG. 10 is a partial perspective view showing another embodiment of the composite superconducting wire village used in the present invention, and FIG. 11 to 15 are cut end views showing further different embodiments of the composite superconducting wire used in the present invention, and FIG. 16 is a cut end view showing further different embodiments of the composite superconducting wire used in the present invention. Chapter I
Figure T is a cut end view of the composite superconducting wire for comparison with Figure 16. 2... Superconducting wire, 3... Substrate, 4... Insulator, 5, 9... ○-shaped coil,
6...Subesa, 6A...Takako, 7...
・Cooling channel, 8, 14, 18... Composite superconducting wire, 10... Circumferential groove, 11...
Radial groove, 12...Groove between turns. Hair' figure 2 figure 3 figure younger brother 4 figure 5 figure 6 figure 7 figure 8 figure Kaya? Younger Brother Noo Younger Brother No' Drawing Tano 2 Drawing Younger Brother Buddha Drawing Younger Brother /S Younger Brother /ru Drawing Younger Brother / 7th Drawing

Claims (1)

[Scope of Claims] 1. A superconducting wire material in which a substrate in which a superconducting element wire is embedded has a substantially rectangular cross section and is wound spirally through an insulating material to form a coil, wherein the substrate is A superconducting wire characterized in that, at least on a side surface that is perpendicular to the axis of a spirally wound coil, a plurality of protrusions narrower than the width of the side surface are formed intermittently along the longitudinal direction. 2. The superconducting wire according to claim 1, wherein the convex portion formed on the side surface is provided at a central portion in the width direction of the side surface. 3. In the substrate, an insulator is provided on the inner circumferential surface of a pair of winding surfaces perpendicular to the side surface on which the convex portion is formed, and an insulator is provided between the convex portions on the outer circumferential side. The superconducting wire according to claim 1 or 2, characterized in that a groove is formed at a position where the superconducting wire has a groove. 4. The superconducting wire according to claim 1, wherein the substrate is provided with a reinforcing member having a mechanical strength greater than that of the superconducting wire. 5 A plurality of coils are arranged in the axial direction via spacers, each of which is formed by winding a superconducting wire material having an almost rectangular cross section through a substrate in which superconducting wires are embedded into a disk shape by spirally winding the superconducting wire material through an insulator. In the superconducting magnet, each of the coils includes a superconducting wire having a plurality of protrusions narrower than the width of the side surface formed intermittently along the longitudinal direction on at least one side of the substrate, and the protrusions The coil is wound spirally through the insulator by curving a surface perpendicular to the side surface on which the coil is formed, and at least a surface facing the spacer has a plurality of grooves along the circumferential direction of the coil, and these grooves. A superconducting magnet characterized in that a plurality of radial grooves are formed that communicate with each other. 6. The spacer is composed of a flat plate having a plurality of through holes in the axial direction, and each of the coils has a plurality of through holes formed by a plurality of grooves provided along the longitudinal direction of the curved surface of the superconducting wire, and 6. The superconducting magnet according to claim 5, wherein the grooves provided in each coil communicate with each other via a through hole formed in the spacer and a through hole formed in the coil.