JPH1186922A - Connecting part structure for superconducting cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a connecting part for a superconducting cable, having high stability compared with the conventional case and having high performance with few joule loss and alternating current loss. SOLUTION: A superconducting stranded wire is composed by etching the end parts of two conductors consisting of a plurality of stranded superconducting element wires 1 to expose the superconducting filaments 2 in the element wires 1, putting the element wires 1 together to be a bundle, lapping this gathered element wires 1 each other, pressuring and heating the element wires 1 to diffusion-bond the superconducting filaments 2 to each other, and stranding the filaments. The superconducting stranded wires are connected each other by solid phase diffusion. In the cross sections of the above two gathered superconducting filament 2, at least one of low electric resistance metallic foils 7 is arranged in the vertical direction to a direction of the magnetic field added from outside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for connecting a finite-length superconducting cable formed by twisting a plurality of superconducting wires, and particularly to a structure for securing stability and reducing AC loss. The present invention relates to a connection structure for a superconducting cable.

[0002]

2. Description of the Related Art A connection portion of a superconducting cable of this kind is used for a superconducting device such as a superconducting magnet or a superconducting generator of a nuclear fusion device or an energy storage device. In a conventional connection structure for a large-capacity cable, a superconducting stranded wire 4 (4a, 4b) is buried in a large copper low-resistance metal block 6 as shown in FIG. , A low electric resistance metal block 6 and a superconducting stranded wire 4 (4a, 4b) are integrated by a solder 5 or the like.

In addition, the connection structure of a superconducting cable by a solid-state joining method in which the superconducting stabilizing copper is removed and the superconducting filaments are directly connected to each other in order to reduce the generated eddy current loss while keeping the connection resistance small. Are known.

[0004]

In the former connection structure for a superconducting cable, when a part of the superconducting twisted wire 4 (4a, 4b) undergoes normal conduction transition due to some disturbance, the low electric resistance metal block 6 is used. Although the connection method described above is desirable in order to reduce the connection resistance, on the other hand, when a large pulse current is applied to the connection portion itself, there is a problem that an AC loss increases due to an eddy current and adversely affects the superconducting coil.

[0005] On the other hand, in the latter case, the lump of filaments is liable to become large and magnetically unstable, so that a compact connection structure can be obtained as compared with the former connection structure using the low-resistance metal block 6, but sufficient. There is a problem that stable stability cannot be secured.

As described above, the conventional superconducting cable connection structure cannot simultaneously satisfy low loss and high stability, and thus has a problem that sufficient performance cannot be obtained. Therefore, since there is a trade-off relationship between the reduction of the AC loss and the improvement of the stability, there is a need for a superconducting cable connecting portion structure that balances both.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a high-performance superconducting cable connecting portion which has higher stability as compared with the conventional example and has less Joule loss and AC loss. It is in.

[0008]

According to a first aspect of the present invention, an end portion of two conductors composed of a plurality of twisted superconducting wires is etched to expose a superconducting filament in the wire.
One or several strands are bundled together, wrapped together, heated and pressurized, diffusion bonded and twisted together to form a superconducting stranded wire, and this superconducting stranded wire is mutually solid-phase diffused. In the connecting portion structure of the superconducting cable to be joined, at least one of the metal foils having a low electric resistance is arranged in a cross section of the bundled filament in a direction perpendicular to the direction of a magnetic field applied from outside the connecting portion. It is characterized by.

According to the first aspect of the present invention, one or a plurality of low-resistance metal foils are arranged in the bundled filament cross section in the direction perpendicular to the direction of the magnetic field applied from outside the connection portion. As a result, the temperature of some filaments rises due to some disturbance, and when this temperature rise lowers the critical current value at the connection and magnetic flux enters, eddy current flows through this low electric resistance metal and the flux enters In addition to suppressing the speed, the low electric resistance metal generally has a large thermal conductivity, so that the heat generated by the disturbance can be quickly transmitted to the refrigerant, and thus the connection structure of the superconducting cable that is stable against the disturbance. Can provide body.

According to a second aspect of the present invention, fine metal particles or metal filaments of low electric resistance such as copper, aluminum, silver or the like are arranged in the gaps of the superconducting filament portions so that the metal filaments are completely integrated. Prevent from becoming.

According to the second aspect of the present invention, fine metal particles or metal filaments of low electric resistance such as copper, aluminum, silver or the like are arranged in the gaps of the superconducting filaments so that the superconducting filaments are completely bundled together. Can be reduced, the effective filament diameter of the connecting portion can be reduced, and the thermal conductivity of the superconducting filament portion can be increased, so that the heat generated by disturbance can be quickly transmitted to the refrigerant. It is possible to provide a superconducting cable connection structure that is stable against a disturbance and is less likely to cause a flux jump.

According to a third aspect of the present invention, the superconducting filament disposed on the outer periphery of the superconducting wire is removed by removing only the stabilized copper disposed on the outer periphery of the superconducting wire and leaving the stabilized copper at the center of the superconducting wire. Expose. The superconducting filaments are wrapped with each other and diffusion bonded, so that the stabilizing copper exists between the superconducting filaments except for the superconducting filament arranged near the outer peripheral portion. Further, as the length of the connection portion is longer, the AC loss increases, so that the length is minimized.

According to the third aspect of the present invention, only the stabilized copper disposed on the outer peripheral portion of the superconducting wire is removed to expose the superconducting filament on the outer peripheral portion of the wire, and the filaments are wrapped with each other and diffusion bonded. The filament placed near the outer periphery becomes a superconducting junction between the superconducting materials, and since there is stabilized copper etc. between the other filaments as well as the strands, the increase in the effective filament diameter is minimized. Thus, a stable superconducting cable connection structure can be provided.

According to a fourth aspect of the present invention, when the ends of two conductors composed of a plurality of superconducting wires are etched and the exposed superconducting filaments in the wire are wrapped together, the length of the superconducting filaments in the wire is adjusted. Twist pitch of filament (usually 10mm
20mm from the same).

According to the fourth aspect of the present invention, the longer the length of the connecting portion, the greater the AC loss, so that the length is minimized. That is, when the end of the superconducting cable conductor is etched and the exposed superconducting filaments in the superconducting wire are wrapped together, the length is set to the twist pitch of the superconducting filament in the superconducting wire (usually about 10 mm to 20 mm). Configure to be equal. As a result, since the superconducting filaments on the outer peripheral side are connected substantially equally, the coupling loss can be minimized without increasing the connection resistance.

According to a fifth aspect of the present invention, there is provided a superconducting cable connecting structure in which superconducting stranded wires are inserted into stabilized copper or the like and joined together by soldering or solid-state diffusion bonding. In order to reduce the loss, the connection length is set to be equal to or less than the final twist pitch of the superconducting stranded wire.

According to the fifth aspect of the present invention, in order to reduce the eddy current loss due to the coupling current of the coupling portion, the connection length is set to be equal to or less than the final twist pitch of the superconducting stranded wire, so that the connection between the coupling portions is reduced. A large coupling circuit can be prevented, and AC loss can be reduced.

According to a sixth aspect of the present invention, the ends of the two conductors made of a plurality of superconducting stranded wires are inserted into a low electric resistance metal block sleeve, and an external pressure is applied to the low electric resistance metal block sleeve. In the connection structure of the superconducting cable, which is compressed and solid-phase diffusion-bonded between the superconducting stranded wire and the low electric resistance metal block sleeve, a final twist of the superconducting stranded wire is formed on the inner surface of the low electric resistance metal block sleeve. It is characterized in that uneven portions having a pitch shorter than the pitch are provided.

According to the sixth aspect of the present invention, the connection portion is improved, and the variation in the current caused by the inductance of each superconducting element wire is promptly eliminated. In addition, the contact between the superconducting wire and the low electric resistance metal is made into a large number of point contacts by the uneven portions, so that the contact surface pressure at the contact point can be increased and the connectivity between the superconducting wire and the low electric resistance metal can be improved.

According to a seventh aspect of the present invention, the low electric resistance metal block is formed in a cylindrical block, and the cylindrical block has a spiral shape which is axially symmetric and has a pitch substantially equal to the final twist pitch of the superconducting stranded wire. A groove is formed, and the superconducting stranded wires at both ends connected to both ends of the helical groove are alternately stacked for each group and diffusion-bonded.

According to the seventh aspect of the present invention, it is possible to reduce the difference in inductance between the superconducting wires and quickly eliminate the variation in current caused by the difference in inductance, thereby reducing the coupling loss at the connection. it can.

According to an eighth aspect of the present invention, in the connecting portion structure in which the superconducting stranded wires are accommodated in the low electric resistance metal block, the compression ratio of the superconducting stranded wires in the longitudinal direction of the connecting portion is changed for each twist pitch. It is characterized in that it is configured to be large.

According to the eighth aspect of the present invention, the current can be quickly transferred in the cable, and the stability can be ensured. In addition, since a small portion of the contact resistance appears at every pitch, the coupling current can be increased. Without this, the connection resistance to all superconducting wires can be reduced.

According to a ninth aspect of the present invention, there is provided a superconducting cable connection structure comprising a pair of superconducting strands formed by twisting a plurality of superconducting strands at several stages and lapping and joining the conductor ends of the pair. The final twist of the superconducting stranded wire is tangentially untwisted, and the end of the untwisted superconducting stranded wire is formed in a plate shape.

According to the ninth aspect of the present invention, each superconducting element wire of the last twist is unwound and the cable is guided on the same plane in the tangential direction, formed into a plate shape, and this portion is impregnated with solder or the like. Thus, the AC loss can be reduced as compared with the case where the entire superconducting element wire is compression-molded by the low electric resistance metal block.

According to a tenth aspect of the present invention, the plate portion is housed in a low electric resistance metal block, compression molded, and solid-phase bonded.
It is characterized in that the current is guided perpendicularly to the connection surface. According to the tenth aspect, the current is guided perpendicularly to the connection surface, and the AC loss of the superconducting cable can be reduced.

According to an eleventh aspect of the present invention, each of the superconducting stranded wires is housed in a low-resistance metal block, compression-molded, cut longitudinally from the end thereof, and the cut surfaces are connected together. It is characterized by.

According to the eleventh aspect of the present invention, the section of the superconducting element wire becomes elliptical, the number of times the superconducting filaments come into contact with each other increases, the Joule loss due to the connection can be reduced, and the current is perpendicular to the connection surface. ,
The AC loss of the superconducting cable can be reduced.

[0029]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
Embodiments (examples) of the superconducting cable connecting portion structure according to each of the inventions up to 11 will be sequentially described. First Figure 1
A first embodiment according to the present invention will be described with reference to (a) and (b) and FIG. FIG. 1A is a front view of a superconducting cable connecting portion structure according to the first embodiment.
(B) shows a longitudinal sectional view of FIG. 1 (a).

In FIGS. 1A and 1B, reference numeral 1 denotes a superconducting wire, 2 denotes a superconducting filament, 6 denotes a low electric resistance metal block, and 7 denotes a low electric resistance metal foil. In FIG. 2, reference numeral 8 denotes a critical current characteristic curve of the superconducting wire, 9 denotes a quench current characteristic curve of the improved connection part of the present invention, and 10 denotes a quench current characteristic curve of the conventional connection part.

That is, in the first embodiment, the ends of two conductors composed of a plurality of twisted superconducting wires 1 are etched to expose the superconducting filaments 2 in the superconducting wires 1 and collectively. The superconducting wires 1 are wrapped with each other, heated under pressure, and the superconducting filaments 2 are diffused and joined to form a superconducting cable. In the joint structure of a superconducting cable in which the superconducting cables are joined to each other by solid-phase diffusion, a resistor having a small electric resistance, that is, a metal foil 7 having a low electric resistance, is connected in a cross section of the united superconducting filament 2. Are arranged in a direction perpendicular to the direction of the magnetic field applied from outside.

In the second embodiment of the present invention, metal particles or metal filaments of low electric resistance such as copper, aluminum, silver or the like are arranged in the gaps between the two superconducting filaments.

In the third embodiment of the present invention, a plurality of superconducting wires 1 (1a, 1a) twisted as shown in FIG.
b), the ends of the two conductors made of superconducting filament 2 (2) in superconducting wire 1 (1a, 1b) are etched.
a, 2b) are exposed, the superconducting wires 1 (1a, 1b) are put together, wrapped with each other, heated under pressure,
The superconducting filaments 2 (2a, 2b) are diffusion bonded and twisted to form a superconducting cable.

In the superconducting cable connecting portion structure in which the superconducting cables are joined to each other by solid phase diffusion, a low electric resistance metal, for example, a stabilized copper 3 disposed on the outer peripheral portion of the superconducting wires 1 (1a, 1b). (3a, 3a ', 3b,
3b ') is removed, and the portion where the superconducting filament 2 is exposed on the outer periphery of the superconducting wire 1 is solid-phase bonded.

The fourth embodiment of the present invention differs from the third embodiment in that the stabilized copper 3 (3a, 3a ', 3
b, 3b ') are removed from the superconducting filament 2 (2a, 2b) of the superconducting wire 1 (1a, 1b).
That is, the twist pitch is set to be equal to or more than b).

According to a fifth embodiment of the present invention, as shown in FIG. 5, in a superconducting cable connecting portion structure in which ends of two conductors composed of a plurality of superconducting wires are wrapped and joined to each other, The purpose of the present invention is to maintain the connection length of the bundled cables to be joined to each other at a final (n-th) twist pitch 11 or more of the superconducting stranded wire 4.

According to a sixth embodiment of the present invention, as shown in FIG. 6, the ends of two conductors composed of a plurality of superconducting stranded wires 4 (4a, 4b) are connected to a sleeve composed of a metal block 6 having a low electric resistance. And a sleeve made of the superconducting stranded wires 4 (4a, 4b) and the metal block 6 having a low electric resistance is solid-phase diffusion-bonded to the sleeve. The reason is that uneven portions 6a and 6b having a pitch shorter than the final twist pitch of the superconducting stranded wires 4 (4a and 4b) are provided on the inner surface of the sleeve made of the electric resistance metal block 6.

FIG. 2 is a characteristic curve diagram relating to stability when a copper foil, a copper filament or copper fine particles having a low electric resistance is arranged in a gap where the superconducting filaments 2 in the above embodiment are grouped together. The ordinate shows the empirical magnetic field, and the ordinate shows the quench current.

As shown in FIG. 2, in order to obtain a sufficient conduction current close to the critical current even at a relatively low magnetic field, as in the first embodiment, the second embodiment, and the third embodiment, It can be seen that it is desirable that a low electric resistance metal or the like is disposed inside the superconducting filament 2 so as to prevent integration of the superconducting filament 2 as much as possible.

When the external magnetic field applied to the superconducting filament 2 does not change depending on the location and time of the connecting portion, as shown in FIG. 1, the foil 7 having a low electric resistance such as copper is placed in a direction perpendicular to the external magnetic field. (First embodiment), it is possible to effectively suppress a flux jump that may occur when a temperature rises due to disturbance or the like.

When the direction of the magnetic field changes depending on the place or time, or when there is not enough space for installing copper foil or the like, the method according to the second and third embodiments is used as shown in FIG. In addition, the superconducting filament, which has a low electrical resistance and high thermal conductivity, is scattered throughout the superconducting filament to suppress the temperature rise due to disturbances and reduce the size of the substantial superconducting filament mass. Thus, heat generation at the time of entering the magnetic flux can be reduced, and quenching can be avoided.

In particular, in the case of the configuration of the third embodiment shown in FIG. 3, that is, the stabilized copper 3 (3a, 3a ', 3b, 3) arranged on the outer periphery of the superconducting wire 1 (1a, 1b).
The superconducting filaments 2 (2a, 2b) exposed at the outer periphery of the superconducting element wire 1 are removed and only the superconducting filaments 2 are wrapped together and diffusion bonded.

As a result, the superconducting filaments 2 arranged in the vicinity of the outer peripheral portion are in contact with each other, so that a superconducting junction without a normal conducting metal is interposed therebetween, and the other filaments are stable like the superconducting wire 1. Because of the presence of copper oxide 3 and the like, an increase in the diameter of the effective superconducting filament 2 can be minimized, and a stable superconducting cable connection structure can be provided.

Generally, the twist of the superconducting cable is loosened in the vicinity of the connecting portion, and the vertical electric resistance of the superconducting cable is small, so that the coupling loss increases in accordance with the length of the connecting portion. The fourth embodiment has a configuration that minimizes the length of the connecting portion.

According to the present invention, the end of the superconducting cable conductor is etched so as to be equal to the twist pitch of the superconducting filament 2 in the superconducting wire 1 (usually about 10 mm to 20 mm). Since the superconducting filaments arranged on the side are connected equally, the effect of shortening the length without increasing the connection resistance appears and the coupling loss can be minimized.

A conventional lap-type connecting portion in which the superconducting stranded wires 4a and 4b as in the conventional example shown in FIG. 13 are inserted into a low electric resistance metal block 6 and joined together by solder 5 or solid phase diffusion bonding or the like. The structure reduces eddy current losses due to large loop coupling currents flowing between the junctions. Therefore, as shown in FIG. 5, by configuring the connection length to be equal to or less than the final twist pitch ln of the superconducting stranded wire, it is possible to prevent a large coupling circuit from being formed between the connection portions and reduce the AC loss. .

That is, when a connection portion having a length of not less than the final twist pitch 11 is lap-joined, a very large coupling current loop is formed as shown in FIG. Causes a large coupling loss at the contact point, but if it is manufactured with a length of less than one pitch, this coupling current loop does not occur. In FIG. 7, reference numeral 13 is a contact point, 14 is a coupling current loop, and 15 is the direction of an externally fluctuating magnetic field.

In order to improve the bonding between the low-resistance metal block (also referred to as a sleeve) 6 and the superconducting stranded wire 4, the inner surface of the low-resistance metal block 6 compressed by applying an external pressure as shown in FIG. A configuration in which the uneven portions 6a are provided at a pitch shorter than the minimum twist pitch of the stranded wires 4, for example, the inner surface of the low electric resistance metal block 6 is subjected to thread processing.

As a result, the superconducting stranded wire 4 intersects with the concave and convex portions 6a of the low electric resistance metal block 6, and by providing these many contact points, the contact surface pressure at the contact points is increased to increase the superconducting stranded wire. 4 and the low electrical resistance metal block 6 can be improved.

Next, a seventh embodiment of the present invention will be described with reference to FIGS. In the seventh embodiment of the present invention, the low electric resistance metal block 6 as the sleeve shown in FIG. 6 is formed into a cylindrical block as shown in FIG. 8, and the cylindrical block is axially symmetrical and shown in FIG. A plurality of spiral grooves 6c twisted equal to the final twist pitch 11 of the superconducting twisted wire 4 shown are formed, and the superconducting twisted wires at both ends connected to the spiral groove 6c are alternately arranged in several groups. That is, they are stacked and diffusion bonded.

According to the present invention, the inductance between the superconducting wires is reduced, the variation in the current caused by the difference between the individual wire inductances is quickly eliminated, and the coupling loss at the connection portion is reduced.

Next, an eighth embodiment of the present invention will be described with reference to FIG. In FIG. 9, in the connecting portion structure in which the superconducting stranded wires 4 are accommodated in the low-resistance metal block 6, the compression ratio of the superconducting stranded wires 4 in the longitudinal direction of the connecting portion is increased for each twist pitch. It is in. In FIG. 9, reference numeral 11 denotes a final (n-th) twist pitch, and reference numeral 12 denotes an (n-1) -th twist pitch.

That is, in the present embodiment, the compression ratio in the longitudinal direction of the n-th stranded wire is increased by one twist before the final twist, that is, at every (n−1) -th twist pitch, and the element of the portion having a high compression ratio is increased. Make the resistance between lines small.

As a result, high current can be transferred quickly in the sub-cable, so that high stability can be ensured. In addition, a small portion of the contact resistance appears at every pitch, so that even if an external magnetic field is applied, the magnetic flux within one pitch Is canceled,
No coupling current is generated, the loss does not increase, and the connection resistance to all the wires can be reduced.

Next, a ninth embodiment of the present invention will be described with reference to FIG. In FIG. 10, a pair of superconducting twisted wires 4 (4a, 4a) formed by twisting a plurality of superconducting strands in several stages are formed.
In the joint structure of the superconducting cable in which the conductor ends are wrapped and joined to each other in the superconducting stranded wire 4 (4a, 4b)
The reason is that the final twist of b) is tangentially untwisted, and the ends of the untwisted superconducting stranded wires 4 (4a, 4b) are formed in a plate shape.

As shown in FIG. 10, the final twisted cables are untwisted, the cables are guided on the same plane in the tangential direction, the cables are formed into a plate shape, and this portion is impregnated with solder or the like, so that the entire cable is compressed by the sleeve. The AC loss can be reduced as compared with the case of molding.

Next, a tenth embodiment of the present invention will be described with reference to FIG. In the present embodiment, as shown in FIG. 11, the ends of the superconducting stranded wires 4 (4a, 4b) are housed in low electric resistance metal blocks 6 (6a, 6b), respectively, as shown in FIG. In this case, the plate-shaped portions are overlapped with each other and solid-phase bonded, and a current is guided perpendicularly to the bonding surface.

According to the present embodiment, the low electric resistance metal block 6 (6a, 6b) and the superconducting stranded wire 4 (4a, 4b)
Of the superconducting stranded wire to form an airtight structure,
In addition, because of the solid-phase bonding, the current is guided perpendicularly to the connection surface of the plate-shaped portion, and the AC loss of the superconducting cable can be reduced.

Next, an eleventh embodiment of the present invention will be described with reference to FIG. In the present embodiment, superconducting element wire 1 (1a, 1
b) and a superconducting stranded wire 4 (4a, 4
b) is replaced with a low electric resistance metal block 6 (6a, 6a).
b), cut vertically from its end, and connect the cut surfaces together.

In the connection portion of the eleventh embodiment, as shown in FIG. 12, the cut superconducting element wire has an elliptical shape,
The number of times the superconducting filaments in the superconducting element wire come into contact with each other increases, and the Joule heat generated by the connection can be suppressed,
The current is guided perpendicular to the connection surface. Therefore, the AC loss of the superconducting cable can be reduced.

[0061]

According to the first aspect of the present invention, the temperature of some of the superconducting filaments rises due to some disturbance, and this rise in temperature lowers the critical current value of the connection portion, and when the magnetic flux enters, this low temperature rises. An eddy current flows through the electric resistance metal and the speed of entry of the magnetic flux can be suppressed, and the low electric resistance metal has a large thermal conductivity, so that the heat generated by the disturbance can be quickly transmitted to the refrigerant, and therefore, the resistance to the disturbance can be reduced. A stable superconducting cable connection structure can be provided.

According to the second aspect of the present invention, it is possible to prevent the superconducting filaments from completely forming one block, to reduce the effective filament diameter of the connecting portion, and to reduce the thermal conductivity of the superconducting filament portion. Since it is possible to increase the size and to quickly transmit the heat generated by the disturbance to the refrigerant, it is possible to provide a connection portion that is stable against the disturbance and is less likely to cause a flux jump.

According to the third aspect of the present invention, the superconducting filament disposed in the vicinity of the outer periphery becomes a superconducting junction between superconducting materials, and stabilized filaments or the like exist between the other filaments as in the superconducting element wire. Therefore, an increase in the effective filament diameter can be minimized, and a stable connection portion can be provided. According to the fourth aspect of the present invention, since the superconducting filaments on the outer peripheral side are connected substantially evenly, the coupling loss can be minimized without increasing the connection resistance.

According to the fifth aspect of the present invention, by setting the connection length to be equal to or less than the final twist pitch of the superconducting cable, it is possible to prevent a large coupling circuit from being formed between the connection portions and reduce the AC loss. .

According to the sixth aspect of the present invention, the contact between the superconducting stranded wire and the low electric resistance metal sleeve is made a large number of point contacts, so that the contact surface pressure at the contact point is increased and the distance between the superconducting stranded wire and the sleeve is increased. Connectivity can be improved.

According to the seventh aspect of the present invention, the difference in inductance between the superconducting wires is reduced, and the variation in current caused by the difference in inductance is quickly eliminated, so that the coupling loss at the connection portion can be reduced. .

According to the eighth aspect of the present invention, the current transfer in the superconducting cable can be performed promptly, the stability is ensured, and a portion having a small contact resistance appears at every pitch. , And the contact resistance to all superconducting wires can be reduced.

According to the ninth aspect of the present invention, the final twisted cables are untwisted, the cables are guided on the same plane in the tangential direction, and the cables are formed into a plate shape, and this portion is impregnated with solder or the like, thereby forming a sleeve. The AC loss can be reduced as compared with the case where the entire cable is compression molded.

According to the tenth aspect of the present invention, the plate portion and the superconducting stranded wire are covered with a low electric resistance metal block and formed into a plate shape so that there is no gap, and the plate portion and the superconducting stranded wire are hermetically sealed. Therefore, the current is guided perpendicularly to the connection surface of the plate-shaped portion, and the AC loss of the superconducting cable can be suppressed to a small value.

According to the eleventh aspect of the present invention, the cross section of the superconducting element wire becomes elliptical, the number of times the superconducting filaments come into contact with each other increases, the Joule loss due to the connection can be reduced, and the electric current flows to the connection surface. They are guided vertically,
The AC loss of the superconducting cable can be reduced.

[Brief description of the drawings]

FIG. 1 (a) is a front view showing a first embodiment of a superconducting cable connecting portion structure according to the present invention, and FIG. 1 (b) is (a).
FIG.

FIG. 2 is a characteristic diagram of an empirical magnetic field and a quench current for comparing an example of the present invention with a conventional example.

FIG. 3 is a perspective view showing a connection structure of a superconducting cable according to a third embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a connection portion structure of a superconducting cable according to second and third embodiments of the present invention.

FIG. 5 is a perspective view showing a connection structure of a superconducting cable according to a fifth embodiment of the present invention.

FIG. 6 is a sectional view showing a connection portion structure of a superconducting cable according to a sixth embodiment of the present invention.

FIG. 7 is a schematic diagram for explaining a coupling current loop flowing between connecting portions of the superconducting cable in FIG. 5;

FIG. 8 is a perspective view showing a cylindrical block used in a connection structure of a superconducting cable according to a seventh embodiment of the present invention.

FIG. 9 is a perspective view showing a compressed portion in a connection structure of a superconducting cable according to an eighth embodiment of the present invention.

FIG. 10 is a perspective view showing a connection structure of a superconducting cable according to a ninth embodiment of the present invention.

FIG. 11 is a perspective view showing a connection portion structure of a superconducting cable according to a tenth embodiment of the present invention.

FIG. 12 is a perspective view showing a connection structure of a superconducting cable according to an eleventh embodiment of the present invention.

FIG. 13 is a perspective view illustrating a configuration example of a conventional connection portion.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Superconducting element wire, 2 ... Superconducting filament, 3 ... Stabilized copper, 4 ... Superconducting twisted wire, 5 ... Solder, 6 ... Low electric resistance metal block, 7 ... Low electric resistance metal foil, 8 ... Critical current of superconducting wire Characteristic curve, 9: Improved quench current characteristic curve of the connection part, 10: Quench current characteristic curve of the conventional connection part, 11: Final (n-order) twist pitch, 12: n-1 order twist pitch, 13 ...
Contact point, 14 ... coupling current loop, 15 ... direction of external fluctuating magnetic field.

Continuation of the front page (72) Inventor Tomoyuki Sasaki 1-1-1, Shibaura, Minato-ku, Tokyo Inside Toshiba head office

Claims (11)

[Claims] 1. An end portion of two conductors comprising a plurality of twisted superconducting wires is etched to expose a superconducting filament in the superconducting wires, and the superconducting wires are grouped one by one or several at a time. The superconducting filaments are wrapped together, heated and pressurized, and the superconducting filaments are diffusion-bonded and twisted to form a superconducting stranded wire. The superconducting stranded wires are mutually bonded by solid phase diffusion. In the superconducting cable connecting portion structure, at least one piece of the low electric resistance metal foil is disposed in a direction perpendicular to the direction of a magnetic field applied from the outside of the connecting portion within the cross section of the collective superconducting filament portion. A superconducting cable connection structure. 2. The superconducting cable according to claim 1, wherein metal particles or metal filaments of low electric resistance, such as copper, aluminum, and silver, are arranged in the gaps of the superconducting filaments. Connection structure. 3. An end of two conductors composed of a plurality of twisted superconducting wires is etched to expose a superconducting filament in the superconducting wires, and the superconducting wires are grouped one by one or several at a time. A superconducting cable in which the bundled wires are wrapped with each other, pressurized and heated, and the superconducting filaments are diffusion-bonded and twisted to form a superconducting stranded wire, and the superconducting stranded wires are mutually joined by solid-phase diffusion. A superconducting cable, wherein only the stabilized copper disposed on the outer peripheral portion of the superconducting wire is removed and the exposed portion of the superconducting filament on the outer peripheral portion of the superconducting wire is solid-phase bonded. Connection structure. 4. The superconducting cable connecting portion structure according to claim 3, wherein the length of the connecting portion from which only the stabilizing copper is removed is longer than the twist pitch of the superconducting filament of the superconducting wire. 5. A connecting structure for a superconducting cable in which the ends of two conductors composed of a plurality of superconducting wires are wrapped and joined to each other, the length of the connecting portion of the group of cables joined to each other is set to be superconducting. A connection structure for a superconducting cable, wherein the connection is maintained at a pitch equal to or greater than the final twist pitch of the stranded wires. 6. An end of each of two conductors composed of a plurality of superconducting stranded wires is inserted into a sleeve made of a low electric resistance metal block, and compressed by applying an external pressure to the sleeve made of a low electric resistance metal block. In a connection structure of a superconducting cable in which a stranded wire and the low electric resistance metal block sleeve are solid phase diffusion bonded, a pitch of a pitch shorter than a final twist pitch of the superconducting stranded wire is formed on an inner surface of the low electric resistance metal block sleeve. A connection structure for a superconducting cable, characterized in that it has an uneven portion. 7. The low electric resistance metal block is formed in a cylindrical block, and a spiral groove having an axial symmetry and a pitch substantially equal to a final twist pitch of the superconducting stranded wire is formed in the cylindrical block. 7. The superconducting cable connecting part structure according to claim 6, wherein the superconducting stranded wires at both ends connected to both ends of the spiral groove are alternately stacked and diffused and joined in several groups. 8. A superconducting cable connecting portion structure in which the superconducting stranded wires are accommodated in the low electric resistance metal block, wherein the compression ratio of the superconducting stranded wires in the longitudinal direction of the connecting portions increases with each twist pitch. The connection structure for a superconducting cable according to claim 6, wherein the connection portion structure is configured as described above. 9. A superconducting cable connecting portion structure comprising a pair of superconducting strands formed by twisting a plurality of superconducting strands and wrapping and joining the conductor ends to each other. Twist the final twist of tangentially back,
A connection structure for a superconducting cable, wherein an end of the untwisted superconducting stranded wire is formed in a plate shape. 10. The apparatus according to claim 1, wherein said plate-shaped portion is housed in a low electric resistance metal block, compression molded and solid-phase bonded, and a current is guided perpendicularly to a connection surface thereof. 10. A connection structure for a superconducting cable according to claim 9. 11. The superconducting stranded wires are each housed in a low-resistance metal block, compression-molded, cut longitudinally from the end thereof, and the cut surfaces are joined together and connected. Item 10. A superconducting cable connection part structure according to item 9.