JP2010262933A - Superconducting cable and magnet using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a superconducting cable for a large current, having sufficient cable performance with high stability and little loss, and to provide a magnet that uses the cable. <P>SOLUTION: The superconducting cable includes a core 1 in the center; and superconducting element wires 2, 3, 4, 5, 6 disposed at the periphery of the core 1 as three or more coaxial layers. In each layer, the superconducting element wires are twisted together. The superconducting element wires are twisted at shorter pitches than or equal to those of the innermost layer in all the layers except for the innermost layer. Superconducting element wires coated with a conductive material and normal superconducting element wires are arranged alternately, in each layer of the superconducting element wires. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a superconducting cable used for superconducting equipment and a superconducting magnet using the cable.

  A superconducting cable is used as a conductor for connecting a power source and a superconducting coil, a power transporting conductor, and a superconducting coil using this as a winding. Superconducting coils using these superconducting cables are widely used for superconducting magnetic energy storage (SMES), superconducting coils for fusion devices, and the like. Since the superconducting cable is intended to be used for supplying a large current, the superconducting cable is configured by combining a number of superconducting wires.

  In superconducting cables that combine a number of superconducting wires, it is difficult to equalize the inductance of each superconducting wire, and efforts to reduce the difference in inductance by twisting, twisting, and braiding superconducting wires are difficult. Have been paid.

  Also, the design differs greatly depending on whether it is used as a direct current conductor or an alternating current conductor, low temperature superconductivity or high temperature superconductivity.

  However, regardless of whether the conductor is an AC conductor, a pulse conductor, or a DC conductor, the induced voltage generated when a current is passed is a DC current (connection resistance) included in the line, and a high-temperature superconducting conductor has a magnetic flux current. If it is not sufficiently small compared to the voltage generated by the resistance, current drift occurs due to a slight difference in inductance between the superconducting wires, and it is possible to pass only a current less than the critical current (or rated current) of the conductor. . Further, in the case of a conductor using a high-temperature superconducting element wire, this drift is eliminated as the magnetic flux flow resistance is increased, but a lot of loss occurs, and the merit of the superconducting conductor may not be fully exhibited.

  Furthermore, when a superconductor is used for a coil or the like, an insulator such as formal or a high resistance material such as CuNi or Cr is arranged on the surface of the element wire in order to reduce coupling loss between superconducting wires caused by a varying magnetic field. Although the electrical resistance between the strands is increased, this measure is effective to reduce the loss, but has an adverse effect on ensuring the stability of the conductor.

Japanese Patent Laid-Open No. 11-25785 Japanese Patent Laid-Open No. 10-312718 Japanese Patent Laid-Open No. 9-45150

  As described above, in a superconducting cable using a large number of superconducting wires, current drift occurs due to the difference in inductance of each superconducting wire, and sufficient performance cannot be exhibited. Further, a cable using a high resistance wire intended to reduce loss cannot exhibit sufficient stability.

  The present invention has been made in view of such circumstances. The purpose of the present invention is to use the superconducting cable for high current and the cable having the high performance, the loss of the superconducting cable, and the high performance. Is to provide a magnet.

  In order to solve the above-described problem, the invention of claim 1 is arranged such that a core is arranged at the center, superconducting wires are arranged on the outer periphery of the core as three or more layers on the same axis, and the superconducting wires are arranged in each layer. In the superconducting cable that is twisted every time, the twist pitch length of the superconducting element wire in all layers other than the innermost layer is set to be equal to or less than the twist pitch length of the innermost layer, and in each layer of the superconducting element wire, a resistor The superconducting cable is characterized in that the superconducting element wires covered by the above and normal superconducting element wires are alternately arranged.

  The invention according to claim 2 is a superconducting structure in which a core is arranged in the center, superconducting wires are arranged on the outer periphery of the core as three or more layers on the same axis, and the superconducting wires are twisted for each layer. In the cable, the superconducting element wire in each layer is set to the same direction, and the twist pitch length of each layer is set to be equal to or less than the inner twist pitch length. The superconducting cable is characterized in that the superconducting wires are alternately arranged.

  According to a third aspect of the present invention, a core is arranged at the center, superconducting wires are arranged on the outer periphery of the core as three or more layers on the same axis, and the superconducting wires are twisted for each layer. In a superconducting cable in which a current forward path and a return path are set for two or more layers and two or more outer layers, the twisting directions of the superconducting wires in the forward layer and the return layer are different from each other and on the inner side While the outer layer has a shorter twist pitch length in the two or more layers that are the forward path or the return path, the outer layer has a twist pitch that is the outer layer in the two or more layers that are the outward path or the return path. The superconducting cable is characterized in that in each layer of the superconducting element wires, superconducting element wires covered with resistors and normal superconducting element wires are alternately arranged.

  The invention according to claim 4 is the superconducting cable according to any one of claims 1 to 3, wherein the resistor is made of any one of CuNi, Cr, and formal.

  A fifth aspect of the present invention is a magnet using the superconducting cable according to any one of the first to fourth aspects as a winding.

  According to the superconducting cable and the magnet using the superconducting cable according to the present invention, it is possible to effectively suppress current drift and to have high stability, which can provide excellent effects in the field of fusion devices and the like. it can.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows the superconducting cable by 1st Embodiment of this invention, (a) is a figure which shows the whole structure of the superconducting cable of 3 layer structure, (b) is a figure which shows to the 2nd layer of (a), ( c) A diagram showing only the first layer. (A), (b) is a graph which shows the relationship with respect to the twist pitch of an innermost layer (1st layer) about each twist pitch of the superconducting strand corresponding to the said 1st Embodiment. An example of the superconducting cable by 2nd Embodiment of this invention is shown, (a) is a block diagram of the superconducting cable of a multilayer coaxial structure, (b), (c) is a figure which shows the 2nd layer and the 1st layer, respectively. (A), (b) is a graph which shows the relationship of each twist pitch of the superconducting cable which concerns on 2nd Embodiment, respectively. An example of the superconducting cable by 3rd Embodiment of this invention is shown, (a) is a block diagram of the superconducting cable of a multilayered coaxial structure, (b), (c) is a figure which shows the stranded wire of a sending side and a return side, respectively. (A) is a figure which shows an example of the superconducting cable by 4th Embodiment of this invention, (b) is an axial orthogonal cross section. The figure which shows the modification of the said 4th Embodiment, and shows the structure which has arrange | positioned the insulator between layers and ensured the electrical insulation between layers. The figure which shows the structure using the insulating spacer in the other modification of the said 4th Embodiment. The figure which shows another modification of the said 4th Embodiment, and shows the structure which has arrange | positioned alternately the superconducting strand which coat | covered the high resistance body, and a normal strand. It is a figure for demonstrating the effect | action of the said 4th Embodiment, and is a graph which shows the relationship between the electric resistance of an electrical short circuit part, and the ratio of the electric current which can transfer to an adjacent line. It is a figure for demonstrating the effect | action of the said 4th Embodiment, and is a graph which shows the time change of cooling capacity and the emitted-heat amount. (A), (b) is a figure which shows 5th Embodiment of this invention, and shows an example of the superconducting cable stored in a conduit. The figure which shows the modification of the said 5th Embodiment. The figure which shows another modification of the said 5th Embodiment.

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

[First Embodiment (FIGS. 1 and 2)]
FIG. 1A shows an example of a three-layer structure as the high-temperature superconducting cable according to the present embodiment. FIG. 5B shows the first and second layers, and FIG. 5C shows only the first layer.

This high-temperature superconducting cable is configured by winding superconducting wires 2, 3, and 4 having a circular cross section as a plurality of layers around a core made of a tubular pipe 1 disposed at the center. The superconducting wires 2, 3 and 4 of each layer include NbTi wires, Nb ₃ Sn wires, Nb ₃ Al wires, etc. used at the liquid helium temperature, as well as oxide high temperature superconducting wires (for example, Bi2212, Bi2223, etc.). Wire material is applied.

In this embodiment, the twist pitch length of the superconducting element wires 3 and 4 of the second and third layers on the outer layer side is set shorter than that of the first superconducting element wire 2 that is the innermost layer. That is, the lengths of the arrow lines shown as ½ pitches in FIGS. 1A, 1B and 1C represent the twist pitch lengths of the respective layers, and in this embodiment, the innermost layer is thus formed. It is set to be equal to or lower than the innermost layer in all the layers other than.
In addition, in this embodiment, it is as what is called alternate twist which changed the twist direction for every layer.

In general, a superconducting conductor for supplying a large current is used by bundling hundreds to thousands of superconducting strands. However, the inductances are not equal in the conductors bundling such many superconducting strands. In a superconducting wire having a resistance of 0, a large current drift occurs. That is, in a superconducting cable in which a large number of superconducting wires are not arranged geometrically at all equal to each other, it is difficult to pass an equal current through each superconducting wire, and as a result, the superconducting power supply the most current. The wire will determine the capacity of the cable.
Therefore, in a superconducting cable in which such a large number of superconducting wires are combined, it becomes a big problem how to arrange the inductances of the respective superconducting wires.

  As shown in FIGS. 1A and 1B, in the high-temperature superconducting cable of this embodiment, the superconducting wires 2, 3 and 4 are twisted geometrically symmetrically around the central pipe 1 In this case, the superconducting wires 2, 3 and 4 are completely geometrically symmetric in each layer, and the inductances of the wires are all equal.

  On the other hand, as shown in FIG. 1 (c), in a superconducting cable having only one layer, the inductance of each superconducting element wire 2 can be made equal by arranging them coaxially, and current drift is avoided. it can. However, when the number of strands is several hundreds or thousands, it is practically impossible to form a cable with only one layer because the current density of the conductor is extremely lowered.

  On the other hand, a multi-layer coaxial cable configuration is required, but the problem here is that if conductors with the same twist pitch length in all layers are manufactured, the electromagnetic coupling (impedance between the layers) Difference in the current value flowing in each layer. More specifically, it is known that the current flows more easily in the outer layer.

  Therefore, in the present invention, in order to prevent drift between layers, the twist direction is changed for each layer or the twist pitch length is changed for each layer. In this embodiment, the second and third layers on the outer layer side are considered. The twist pitch length of the superconducting element wires 3 and 4 in the layer is made shorter than that of the first superconducting element wire 2 which is the innermost layer, thereby preventing the drift between the layers.

  Next, the relationship between the twist pitch lengths will be described with reference to FIGS. FIG. 2A specifically shows an example in which the relationship of the twist pitch length in the coaxial cable having a three-layer structure of alternately twisted is obtained by calculation. As shown in FIG. 2A, in a cable with a three-layer structure, for example, when the twist pitch of the first layer is 500 mm, the second layer is 32 mm and the third layer is 34 mm.

  FIG. 2B shows the case of a four-layer structure. In this case, as shown in FIG. 2B, the twist pitch length of the first layer is 500 mm, the second layer is 43 mm, the third layer is 17 mm, and the fourth layer is 25 mm.

  As described above, the current drift between the layers is caused by the circumferential magnetic field generated by the current flowing in the superconducting element wire, but according to the present embodiment, the twist pitch length of the outer layer is made shorter than the twist pitch length of the innermost layer. By doing so, it is possible to generate a magnetic field in the conductor axial direction that cancels the circumferential magnetic field that causes the drift, thereby preventing current drift.

[Second Embodiment (FIGS. 3 and 4)]
FIG. 3A illustrates a superconducting cable according to the second embodiment of the present invention.

  In this superconducting cable, the superconducting wires 2, 3, and 4 having a circular cross section are set around the pipe 1 arranged at the center, and the twist direction of each layer is set to the same direction, and the twist pitch length is shortened toward the outside. And wound around three layers. FIG. 3B shows up to the second layer, and FIG. 3C shows only one layer.

  According to this embodiment, the same effects as those of the first embodiment described above are obviously obtained. However, as a clear difference from the alternating twist, the axial direction for canceling the circumferential magnetic field causing the drift is also provided. The point which can utilize a magnetic field efficiently is mentioned.

  That is, in the alternately twisted coaxial cable shown in the first embodiment, adjacent layers emit magnetic fields in the conductor axial directions that are opposite to each other, so that the circumferential magnetic field that causes the drift can be efficiently canceled. Although this is not possible, this embodiment can be overcome.

  FIGS. 4A and 4B show the relationship between the twist pitch lengths obtained by specific calculation. As shown in FIG. 4 (a), in the case of a three-layer twisted cable, for example, the first layer has a twist pitch length of 500 mm, and the second layer has a configuration of 150 mm and the third layer has a configuration of 275 mm. Therefore, as shown in FIG. 4B, in the case of a four-layer cable, for example, the twist pitch length of the second layer is 325 mm, whereas the twist pitch length of the second layer is 325 mm. By selecting a configuration of 200 mm and the fourth layer of 125 mm, it is possible to suppress the drift between the layers.

  In FIG. 4, when the twist pitch length of all the layers is set to 50 mm, the currents flowing between the layers seem to coincide with each other, but the actual values are shifted by about 1 mm. If all layers have a pitch of 50 mm, a large current drift occurs with a slight difference. Accordingly, when considering the production of a cable, it is preferable to select a twist pitch length as large as possible.

  According to the present embodiment, all the coaxial cables are twisted in the same direction, and at least the twist pitch of each layer is equal to or less than the twist pitch length of the innermost layer, so that the drift between layers can be prevented. It is possible to prevent performance degradation and loss increase.

[Third Embodiment (FIG. 5)]
Next, FIGS. 5A, 5 </ b> B, and 5 </ b> C exemplify the cable of the third embodiment having a current forward path (feed side) and a return path (return side: return) in a coaxial cable. is there. In this example, a four-layer structure is shown, and the first and second superconducting wires 2 and 3 arranged on the inner side serve as the sending side, and the third and fourth superconducting wires arranged on the outer side. Reference numerals 5 and 6 are return sides. The twisting directions of the sending layer and the returning layer are different from each other.

  In this case, as shown in FIG. 5B, the twist pitch length is made smaller toward the outer side (second layer) in each layer (first layer, second layer) arranged on the inner side, and FIG. As shown in (c), in each of the return-side layers (third layer and fourth layer) arranged on the outer side, the outer layer (fourth layer) has a larger twist pitch length. An insulating sheet 7 is interposed between the third layer and the fourth layer, and electrical insulation between the round trip paths is achieved.

In this embodiment, such a configuration can prevent drift between the layers of the superconducting element wires 2 and 3 on the sending side and the superconducting element wires 5 and 6 on the return side. In the case of a cable having no return path (return), the axial magnetic field for canceling the circumferential magnetic field has been formed by configuring the twist pitch length of the outer layer shorter than the innermost layer. The circumferential magnetic field formed by the return path (return) is opposite to the magnetic field formed by the forward path, and the effect of suppressing the drift of the forward path is exhibited.
Although FIG. 5 shows a four-layer cable, it is needless to say that it can be applied to a multilayer cable.

[Fourth Embodiment (FIGS. 6 to 9)]
6A and 6B show an example of the superconducting cable according to the present embodiment.

  This superconducting cable has a period of the least common multiple of the twist pitch lengths of the superconducting wires 2 and 3 of each layer (for example, two layers), and in the axial position for each period, all the layers in the cross section are electrically connected. The electrical short circuit 8 is electrically short-circuited.

  In the configurations of the first embodiment and the second embodiment described above, even when there is no current drift between the layers, it cannot be said that the conductor is necessarily a high-performance conductor against all disturbances. This is because when a single superconducting wire moves due to electromagnetic force and generates heat and the superconducting state breaks down, current cannot be transferred between adjacent insulated wires to adjacent superconducting wires. This is because it cannot be suppressed and the superconducting state of the entire cable is destroyed.

  On the other hand, in this embodiment, all the layers of the cable are electrically short-circuited for each least common multiple of the twist pitch length of each layer, thereby equalizing the conductance of the superconducting element wire of each layer, thereby preventing the current drift. A cable capable of current redistribution between the strands can be configured while maintaining the state.

  Moreover, the electrical short circuit part is formed at shorter intervals by making the twist pitch length of the innermost layer an integral multiple of the twist pitch length of the outer layer. This is because the current redistribution speed between the superconducting wires greatly affects the distance between the short-circuit portions. That is, if the short-circuited part is long, the inductance of the circuit formed between the short-circuited parts will be larger than the resistance generated when the superconducting state collapses due to disturbance, resulting in a larger time constant for current redistribution. . That the time constant is large means that it takes more time for the current to move to another line, which leads to the short-circuit effect not being fully exhibited.

Therefore, in the present embodiment, the short pitch pitch of the short intervals can be realized by setting the twist pitch length of the superconducting element wire 2 in the innermost layer to an integral multiple of the twist pitch length of the superconducting element wire 3 in the outer layer.
In order to make the conductances of the superconducting wires 2 and 3 uniform, it is necessary that the superconducting wires 2 and 3 are electrically insulated.

  Therefore, in this embodiment, as shown in FIG. 7, an insulator (interlayer insulating sheet) 9 is interposed between the layers of the superconducting element wires 2, 3 and 4 in each layer, thereby ensuring electrical insulation between the layers. Yes.

  Also, in the case of a coaxial stranded cable, the superconducting wires 2, 3 and 4 in the same layer are in line contact with each other, so a high resistance body is disposed on the surface of the strand or the strand is hardened by Cr plating or the like. Alternatively, insulation between the strands can be ensured by thin formal insulation (about 10 μm). However, since the wires belonging to different layers are in point contact, this method cannot provide sufficient insulation.

  Therefore, in this embodiment, the insulation between the layers can be ensured by disposing the insulator 9 between the layers. Further, by disposing an insulating sheet or the like between the layers, it is possible to prevent the wires from dropping into the grooves between the wires of other layers and disturbing the inductance.

Furthermore, as shown in FIG. 8, an insulating spacer 10 capable of circulating a perforated sheet or other fluid may be disposed between the layers. By securing the passage of the refrigerant with such a configuration, in addition to the interlayer insulation, it is possible to improve the cooling effect by the refrigerant and constitute a stable conductor.
In addition, stability can also be improved by making a refrigerant | coolant flow through cores, such as the pipe 1 arrange | positioned in the center.

  FIG. 9 also shows a superconducting element wire (surface high resistance line) 11 coated with a high resistance material such as CuNi, Cr, formal, etc. 4 is alternately arranged.

  By adopting such a configuration, the normal superconducting strands 2, 3 and 4 having a good surface cooling are arranged in the vicinity of the poorly cooled strand 11 having an insulating coating, a high resistance body and the like arranged on the surface. And can help improve performance when current redistribution occurs.

As a superconducting element wire used in the superconducting cable of the present embodiment, NbTi wire, Nb ₃ Sn wire, Nb ₃ Al wire, or silver sheath wire of oxide superconducting conductor (Y-based, Bi-based, Tl-based, Hg-based) All the superconducting wires can be applied, and the present invention has excellent effects on these. In particular, low-temperature superconductivity is effective for preventing drift and improving stability by providing an electrical short circuit, and an oxide superconducting wire is effective for reducing loss by preventing drift.

[Operation of Fourth Embodiment (FIGS. 10 and 11)]
In the fourth embodiment described above, various aspects of the superconducting cable provided with the electrical short-circuit portion have been shown. In the present embodiment, the resistance value of the electrical short-circuit portion is defined.
FIG. 10 shows the ratio between the contact resistance between the wires (2Rc) and the normal conduction resistance (Rn) of the electrical short-circuit portion, and the ratio of the current that can be transferred to the adjacent superconducting wire.

  That is, in order for the electrical short-circuit portion to exert its effect, it is necessary to make the resistance value of the electrical short-circuit portion smaller than the maximum normal conductive resistance that can be generated at least one superconducting wire at the short-circuit pitch length. Specifically, the normal conduction resistance per meter when the distance between the electrical short-circuit portions is 1 m, the superconducting wire is 1 mm in diameter, RRR = 100, and the copper ratio is 1, is 1.8E-10 Ωm × 1 m / (0. 5e-3) 2 / π = 0.23 mΩ, and in order for at least the current to move to another superconducting element wire, it is necessary to have a contact resistance lower than this.

  Furthermore, in the superconducting cable provided with the electrical short-circuit portion, the ratio (L / Rn) between the inductance L of the line having at least the short-circuit pitch length and the normal conduction resistance Rn is determined to be smaller than 10 ms.

  FIG. 11 shows the time characteristics of the heat generation and cooling capacity of the superconducting cable. As shown in FIG. 11, the cooling performance of a refrigerant (for example, helium) for cooling a general superconducting wire is superior to the heat generation characteristic of a superconducting cable having a time constant of 1 ms. The heat generation characteristics slightly exceed the cooling performance of the refrigerant. When the superconducting wire undergoes normal conducting transition due to heat generation such as the movement of the strand, the length of the normal conducting portion extending within 10 ms is less than the thermal diffusion distance in the longitudinal direction of the wire, and superconducting using copper as a stabilizing material In the case of a strand, it is about 100 mm.

Further, the inductance of the line between the strands having a diameter of about 1 mm is about 2 × 10 ⁻⁷ H per meter. More specifically, when the refrigerant is supercritical helium of 5K or less, assuming that the normal conduction region extending for 10 ms is 100 mm, the generated resistance at this time is the value of the general superconducting wire described above. Used to be about 2 × 10 ⁻⁵ Ω.

If the line inductance between the short-circuit portions with respect to this normal conducting resistance is 2 × 10 ⁻⁷ H or less, the time constant for current redistribution is 10 ms or less. Therefore, a very stable cable can be provided by setting the short-circuit pitch length to 1 m or less.

  Such a conductor having a short-circuit pitch can be most easily realized when the twisted pitch is short and the twist pitches of the respective layers are all equal in the same-direction twisted coaxial configuration shown in the second embodiment.

[Fifth Embodiment (FIGS. 12 to 14)]
12 (a) and 12 (b) show a cable-in-conduit type short-circuit method, that is, a short-circuit for a configuration in which a superconducting cable that electrically short-circuits each layer periodically is housed in a conduit 13 such as a stainless steel pipe. Shows how.

That is, in this embodiment, as shown in FIGS. 12A and 12B, a pipe diameter increasing portion in which the outer diameter of the core 1 such as a pipe disposed at the center of the cable is increased at the portion that is electrically short-circuited. 12 is provided so that the void ratio of the portion having a large diameter is reduced so that the strands are in good contact with each other.
According to such a configuration, the contact electrical resistance between the strands can be reduced.

As shown in FIG. 13, the inner diameter of the conduit 13 at a portion where it is desired to be electrically short-circuited may be made smaller, contrary to the above. Even with such a configuration, the same effects as described above can be obtained.
On the other hand, FIG. 14 shows a case where an electrical short circuit is devised for a cable having no conduit or the like.

  That is, as shown in FIG. 14, a heat shrink ring 15 having a heat shrinkage rate different from that of the constituent members of the cable is disposed on the outer periphery of the cable at a portion where it is desired to be electrically short-circuited. When this superconducting cable is composed of a non-heat-treating conductor such as NbTi, the heat shrinkage ring 15 has a heat shrinkage rate from room temperature to extremely low temperature from the heat shrinkage rate of the pipe 1 etc. arranged at the center of the conductor. A larger material, such as duralumin, is used so that a compressive force is applied to the part of the ring after cooling. The short-circuit pitch in this case is the same as that in the third embodiment.

  When the superconducting cable is composed of a heat-treated conductor such as Nb3Sn, Nb3Al, or oxide superconductor, the coefficient of thermal expansion from the room temperature to the heat-treating temperature of the metal ring is the heat of the pipe 1 or the like arranged at the center of the conductor. A material smaller than the expansion coefficient, such as tungsten, is used, and a compressive force is applied to this portion during the heat treatment so that diffusion bonding is performed.

  According to the present embodiment, by adopting such a configuration, it is possible to provide an electrical short-circuit portion without performing special work, and it is possible to provide a cable having high stability.

[Other Embodiments]
According to the superconducting cable of each of the embodiments described above, since current drift is suppressed and high stability performance is achieved, this can be applied to a superconducting magnet.
In this case, highly stable characteristics can be obtained as a superconducting magnet.

1 core (pipe)
2, 3, 4, 5, 6 Superconducting wire 7 Insulating sheet 8 Electrical short-circuit portion 9 Interlayer insulating sheet 10 Insulating spacer 11 Surface high resistance wire 12 Pipe diameter increasing portion 13 Conduit 14 Cross-sectional area reducing portion 15 Heat shrink ring

Claims (5)

In a superconducting cable in which a core is arranged in the center, superconducting wires are arranged on the outer periphery of the core as three or more layers on the same axis, and the superconducting wires are twisted for each layer.
The twist pitch length of the superconducting element wire in all layers other than the innermost layer is set to be equal to or less than the twist pitch length of the innermost layer, and in each layer of the superconducting element wire, a superconducting element wire covered with a resistor and a normal superconducting element wire A superconducting cable characterized by alternately arranging and. In a superconducting cable in which a core is arranged in the center, superconducting wires are arranged on the outer periphery of the core as three or more layers on the same axis, and the superconducting wires are twisted for each layer.
The superconducting element wire in each layer is set to the same direction, and the twist pitch length of each layer is set to be equal to or less than the inner twist pitch length. In each layer of the superconducting element wire, a superconducting element wire and a normal superconducting element are covered with a resistor. A superconducting cable characterized by alternately arranging wires. A core is arranged at the center, superconducting wires are arranged coaxially as three or more layers on the outer periphery of the core, and the superconducting wires are twisted for each layer, of which two or more inner layers and two outer layers In the superconducting cable in which the forward and return paths of current are set against the above,
The twisting directions of the superconducting element wires in the forward layer and the return layer are different from each other, and the outer layer has a shorter twist pitch length in the two or more layers that are arranged in the forward or backward direction. On the other hand, in two or more layers that are the outward path or the return path arranged outside, the outer layer has a longer twist pitch, and in each layer of the superconducting element wire, a superconducting element wire covered with a resistor and normal superconductivity A superconducting cable characterized by alternately arranging strands. 4. The superconducting cable according to claim 1, wherein the resistor is made of any one of CuNi, Cr, and formal. A magnet using the superconducting cable according to any one of claims 1 to 4 as a winding.

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