JP5741295B2 - Critical current measuring device and critical current measuring method for superconducting wire - Google Patents

Description

  The present invention relates to a critical current measuring device and a critical current measuring method for a superconducting wire, and more particularly to a critical current measuring device and a critical current measuring method for a superconducting wire having a Hall element portion.

  One of the important characteristics of the superconducting wire is a critical current value (Ic), and the critical current value is one of the important guarantee items of the superconducting wire.

  Japanese Patent Application Laid-Open No. 10-239260 (Patent Document 1) describes a method for obtaining a critical current value by passing a current through a predetermined section of a superconducting wire and measuring a voltage in the predetermined section.

  T. Kono et al., "Evaluation of magnetic homogeneities of Gd-Ba-Cu-O bulk superconductors by different Hall probe scanning methods" (Non-Patent Document 1) scans a bulk superconductor with a Hall element. Thus, a method for observing how a magnetic field is shielded by a superconductor is described.

JP-A-10-239260

T. Kono et al., "Evaluation of magnetic homogeneities of Gd-Ba-Cu-O bulk superconductors by different Hall probe scanning methods", Physica C 426-431 (2005) 632-638

  According to the method for measuring the critical current value of a superconductor described in Japanese Patent Laid-Open No. 10-239260, the critical current value of a superconducting wire is measured every predetermined section, and the critical current below a reference value in a certain section. If a portion having a value was found, it was determined that the superconducting wire in that section had a defect. And the superconducting wire in the section judged to have a defect will be disposed of, but in that case, the superconducting wire part not having the defect will also be discarded together, so the yield of the superconducting wire is not good. It was.

  On the other hand, if the length of the section in which the critical current value is measured is shortened in order to reduce the amount of the discarded portion, the critical current value of the long superconducting wire is long to be measured in all sections. It took time and work efficiency was not good.

  In the above superconducting wire critical current measuring apparatus, superconducting wire defect detection is performed by measuring the critical current value. Therefore, in order to shorten the measurement time, it is effective to measure the critical current of the superconducting wire in the long section. On the other hand, when a defect is found in the superconducting wire, the long section superconducting wire is discarded, resulting in a problem of poor yield.

  The present invention has been made in view of the above problems, and an object thereof is to provide a superconducting wire critical current measuring apparatus and a critical current measuring method capable of measuring the critical current value of a superconducting wire in a short time. That is.

The superconducting wire critical current measuring apparatus according to the present invention includes a critical current measuring unit and a Hall element unit. The critical current measuring unit is for measuring the critical current value in the measured section by measuring the voltage in contact with both ends of the measured section extending along the longitudinal direction of the superconducting wire. The hall element portion is arranged on at least one of the one side and the other side in the longitudinal direction of the section to be measured, and is for measuring a magnetic field changed by the superconducting wire. The superconducting wire critical current measuring device further includes a moving device for moving in the longitudinal direction. The hall element section includes a downstream hall element section arranged on the downstream side of the section to be measured in the moving direction of the superconducting wire by the moving device.

According to the superconducting wire critical current measuring apparatus according to the present invention, the defect detection of the superconducting wire is performed by the Hall element section. Since the Hall element portion can detect the defect of the superconducting wire while moving the superconducting wire relatively without contacting the superconducting wire, the defect of the superconducting wire can be detected in a short time. The critical current measurement unit can also measure the critical current of superconducting wires. Therefore, the measurement time of the critical current value of the superconducting wire when viewed in total can be shortened. With this moving device, the superconducting wire can be moved relative to the Hall element portion and the critical current measuring portion. After measuring the critical current of the superconducting wire, it is possible to detect the presence or absence of defects in the superconducting wire by the downstream Hall element part. When the electrode is pressed against the superconducting wire in order to measure the critical current value, the superconducting wire may be damaged. The downstream Hall element part can detect the presence or absence of defects in the superconducting wire damaged by the critical current measurement.

  In the above superconducting wire critical current measuring apparatus, preferably, the Hall element portion includes an upstream Hall element portion arranged upstream of the section to be measured in the moving direction of the superconducting wire by the moving device.

  Thereby, before measuring the critical current of a superconducting wire, the presence or absence of a defect of a superconducting wire can be detected by the upstream Hall element part. Therefore, by using information on the presence or absence of defects in the superconducting wire, it is possible to efficiently determine the interval in which the critical current value is measured by the critical current measuring unit, and the superconducting wire that has a defect and needs to be discarded Therefore, the yield of superconducting wires can be improved.

  Preferably, in the above superconducting wire critical current measuring apparatus, the critical current measuring unit is capable of measuring a plurality of short-term current values by measuring voltages of a plurality of short sections located in the section to be measured. Includes a short section measurement unit.

  Thereby, since the critical current value of the superconducting wire in a short section can be measured, the critical current value of the superconducting wire can be measured with finer accuracy.

  Preferably, in the above superconducting wire critical current measuring apparatus, the Hall element section includes a plurality of Hall elements arranged in the longitudinal direction of the superconducting wire on at least one of the one side and the other side.

  Thereby, even when noise occurs in one Hall element, the defect of the superconducting wire can be accurately detected by the other Hall element.

  Preferably, in the above superconducting wire critical current measuring apparatus, the Hall element section includes a plurality of Hall elements arranged in the width direction of the superconducting wire on at least one of the one side and the other side.

Thereby, the defect of a superconducting wire is detectable over the width direction of a superconducting wire.
The method for measuring the critical current of a superconducting wire according to the present invention comprises a step of measuring a critical current value and a step of measuring a magnetic field. The step of measuring the critical current value is performed by measuring the voltage in the measured section by bringing the electrodes into contact with both ends of the measured section extending along the longitudinal direction of the superconducting wire. The step of measuring the magnetic field is performed by measuring the magnetic field changed by the superconducting wire by the Hall element portion arranged at least on one side and the other side in the longitudinal direction of the section to be measured.

According to the method for measuring the critical current of a superconducting wire according to the present invention, the defect detection of the superconducting wire is performed by the Hall element portion. Since the Hall element portion can detect the defect of the superconducting wire while moving the superconducting wire relatively without contacting the superconducting wire, the defect of the superconducting wire can be detected in a short time. The critical current measurement unit can also measure the critical current of superconducting wires. Therefore, the measurement time of the critical current value of the superconducting wire when viewed in total can be shortened. The method for measuring the critical current of the superconducting wire further includes a step of moving the superconducting wire in the longitudinal direction between the step of measuring the critical current value and the step of measuring the magnetic field. By the step of moving the superconducting wire in the longitudinal direction, the superconducting wire can be moved relative to the Hall element portion and the critical current measuring portion. The hall element portion includes a downstream hall element portion located on the downstream side in the moving direction of the superconducting wire with respect to the section to be measured. The step of measuring the magnetic field includes the step of measuring the magnetic field changed by the superconducting wire in the downstream Hall element section. A step of measuring a critical current value is performed before measuring the magnetic field in the downstream Hall element section. Thereby, after measuring the critical current of the superconducting wire, the presence or absence of a defect in the superconducting wire can be detected by the downstream side Hall element portion. When the electrode is pressed against the superconducting wire in order to measure the critical current value, the superconducting wire may be damaged. The downstream Hall element part can detect the presence or absence of defects in the superconducting wire damaged by the critical current measurement.

  Preferably, in the above-described method for measuring the critical current of a superconducting wire, the Hall element portion includes an upstream Hall element portion located on the upstream side in the moving direction of the superconducting wire with respect to the section to be measured. The step of measuring the magnetic field includes the step of measuring the magnetic field changed by the superconducting wire in the upstream Hall element section. After measuring the magnetic field at the upstream Hall element part, a step of measuring the critical current value is performed.

  Thereby, before measuring the critical current of a superconducting wire, the presence or absence of a defect of a superconducting wire can be detected by the upstream Hall element part. Therefore, by using information on the presence or absence of defects in the superconducting wire, it is possible to efficiently determine the interval in which the critical current value is measured by the critical current measuring unit, and the superconducting wire that has a defect and needs to be discarded Therefore, the yield of superconducting wires can be improved.

  Preferably, in the method for measuring a critical current of a superconducting wire, the step of measuring a critical current value includes measuring a plurality of short sections by measuring voltages of a plurality of short sections located within a section to be measured of the superconducting wire. A step of measuring each critical current value.

  Thereby, since the critical current value of each short section can be measured, the critical current value of the superconducting wire can be measured with a finer accuracy.

  According to the present invention, the defect detection of the superconducting wire is performed by the Hall element portion. Since the Hall element portion can detect the defect of the superconducting wire while moving the superconducting wire relatively without contacting the superconducting wire, the defect of the superconducting wire can be detected in a short time. The critical current measurement unit can also measure the critical current of superconducting wires. Therefore, the measurement time of the critical current value of the superconducting wire when viewed in total can be shortened.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows Embodiment 1 of the critical current measuring apparatus of the superconducting wire which concerns on this invention. It is a schematic diagram which shows the state by which the Hall element part of the critical current measuring apparatus of the superconducting wire which concerns on this invention is arrange | positioned downstream from a to-be-measured area. It is a schematic diagram which shows the state by which the Hall element part of the critical current measuring apparatus of the superconducting wire which concerns on this invention is arrange | positioned upstream from the to-be-measured area. It is a schematic diagram which shows the state by which the Hall element part of the critical current measuring apparatus of the superconducting wire which concerns on this invention is multiply arranged by the longitudinal direction of a superconducting wire. It is a schematic diagram which shows the state by which the Hall element part of the critical current measuring apparatus of the superconducting wire which concerns on this invention is multiply arranged by the width direction of a superconducting wire. It is a schematic diagram which shows Embodiment 2 of the critical current measuring apparatus of the superconducting wire which concerns on this invention. FIG. 3 is a step diagram illustrating a method for measuring a critical current of a superconducting wire according to the first embodiment. 6 is a flowchart showing a method for measuring a critical current of a superconducting wire according to a second embodiment. It is a figure which shows the relationship between the magnetic field changed with the superconducting wire, and the movement distance of a superconducting wire. It is a figure which shows the relationship between the electric current sent through the superconducting wire, and the voltage of the superconducting wire.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
First, the configuration of the superconducting wire critical current measuring apparatus according to Embodiment 1 of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the critical current measuring device 1 of the superconducting wire 20 mainly includes a critical current measuring unit 2, a hall element unit 6, moving devices 9 and 11, and a liquid nitrogen container 12. . The critical current measuring unit 2 is a part for measuring the critical current value of the section to be measured 3 extending along the longitudinal direction X of the superconducting wire 20.

  The critical current measuring unit 2 includes a pair of voltage electrodes 4, 4, a pair of current electrodes 5, 5, a voltmeter 14, a current source 15, and a PC (Personal Computer) 16. Each of the pair of voltage electrodes 4, 4 is provided so as to be able to contact both ends of the measured section 3 of the superconducting wire 20. Each of the pair of current electrodes 5 and 5 is disposed slightly outside the section to be measured 3 of the superconducting wire 20 and is provided so as to be able to contact the superconducting wire 20. The voltmeter 14 is electrically connected to each of the pair of voltage electrodes 4, 4, and is for measuring the voltage in the measured section 3 when a current is passed through the measured section 3. The current source 15 is electrically connected to each of the pair of current electrodes 5 and 5, and is used for flowing a current through the section to be measured 3. The PC 16 is provided so as to be able to control a measuring device unit 17 including a voltmeter 14 and a current source 15. For example, the PC 16 is provided so as to be able to adjust the current value that is passed through the measured section 3 by the current source 15.

  The hall element portion 6 is disposed on at least one of the one side and the other side in the longitudinal direction X from the measured section 3. In the configuration of FIG. 1, the Hall element section 6 is disposed on both the upstream side 7 (one side) and the downstream side 8 (the other side) of the section 3 to be measured, for example. The Hall element section 6 is for measuring the magnetic field changed by the superconducting wire 20.

  The moving devices 9 and 11 have a feed roller 9 and a receiving roller 11. The superconducting wire 20 before the critical current is measured is wound around the feed roller 9. The feed roller 9 is a part that feeds the superconducting wire 20. The receiving roller 11 is a part that winds the superconducting wire 20 after the critical current is measured. The PC 16 is provided so that the operations of the feed roller 9 and the receiving roller 11 can be controlled. For example, the PC 16 can control the distance and speed at which the superconducting wire 20 is sent, and can control the sending direction (forward direction and reverse direction).

  The liquid nitrogen container 12 is for storing liquid nitrogen 13 therein. The liquid nitrogen container 12 is disposed so that the superconducting wire 20 can be immersed in the liquid nitrogen 13 stored in the liquid nitrogen container 12. The liquid nitrogen 13 stored in the liquid nitrogen container 12 cools the superconducting wire 20 as a measurement object to a critical temperature or lower, and the superconducting wire 20 enters a superconducting state.

  In the above critical current measuring apparatus 1, the case where the Hall element portions 6 are provided on both the upstream side 7 and the downstream side 8 of the measured section 3 has been described. However, as shown in FIG. In addition, the Hall element portion 6 may be provided only on the downstream side 8 as compared with FIG. 3, and the Hall element portion 6 may be provided only on the upstream side 7 relative to the measured section 3 as illustrated in FIG.

  Here, the downstream side 8 is the receiving roller 11 side of the section to be measured 3 in the longitudinal direction X of the superconducting wire 20. In other words, the downstream side 8 is the downstream side 8 from the critical current measurement unit 2 when the superconducting wire 20 flows out of the critical current measurement unit 2 and exits. Further, the upstream side 7 is the side closer to the feed roller 9 than the measured section 3 in the longitudinal direction X of the superconducting wire 20. In other words, the upstream side 7 is the upstream side 7 from the critical current measuring unit 2 when the superconducting wire 20 flows into the critical current measuring unit 2.

  Also, each of the upstream side 7 and downstream side Hall element portions 6 shown in FIG. 1 has a plurality of (for example, two) Hall elements arranged side by side in the longitudinal direction X of the superconducting wire 20 as shown in FIG. 19 may be included. Further, each of the upstream side 7 and downstream side Hall element portions 6 shown in FIG. 1 has a plurality of (for example, two) Hall elements arranged side by side in the width direction Y of the superconducting wire 20 as shown in FIG. 19 may be included. In addition, the distance between the Hall element 19 included in the Hall element portion 6 and the superconducting wire 20 is, for example, 0.5 to 1.0 mm.

  Next, a method for measuring the critical current of superconducting wire 20 of the present embodiment will be described with reference to FIGS.

  As shown in FIG. 1 and FIG. 6, the superconducting wire 20 moves along the longitudinal direction X of the superconducting wire 20 by being sent out from the feeding roller 9 and wound up by the receiving roller 11. As a result, the superconducting wire 20 starts to move relative to the Hall element section 6 and the critical current measuring section 2 (step S1: FIG. 6). In a state where the superconducting wire 20 is moving, the magnetic field changed by the superconducting wire 20 is measured by the Hall element unit 6 disposed on the upstream side 7 of the critical current measuring unit 2 (step S2: FIG. 6). The presence or absence of a defect in the superconducting wire 20 is detected by measuring the magnetic field of the hall element portion 6 on the upstream side 7.

  Here, a method for measuring the magnetic field changed by the superconducting wire 20 by the Hall element portion 6 will be described.

  The Hall element 19 is widely used as a sensor for detecting a magnetic field. In general, when a superconductor is cooled to a critical temperature or less and becomes a superconducting state, an ideal superconductor becomes a complete diamagnetic state by the Meissner effect. The complete diamagnetic state is one of the properties of the superconductor, and is a state in which the internal magnetic field becomes zero by completely eliminating the penetration of the external magnetic field into the superconductor.

  FIG. 9 shows how the magnetic field changed by the superconducting wire 20 changes with respect to the moving distance of the wire of the superconducting wire 20. In the case of the normal superconducting wire 20, the magnetic field is repelled from the inside of the superconductor due to the Meissner effect of the superconductor, so that the strength of the magnetic field detected by the Hall element 19 is higher than the magnetic field of the permanent magnet disposed above the Hall element 19. Becomes smaller. In FIG. 9, the portion where the strength of the magnetic field is low and stable is the portion of the normal superconducting wire 20. On the other hand, in a portion having a defect of the superconductor, even if the superconducting wire 20 is cooled to a critical temperature or less, it does not become a complete diamagnetic state, and therefore the magnetic field cannot be repelled to the outside. For this reason, the magnetic field detected by the Hall element 19 is close to the strength of the magnetic field of the permanent magnet disposed above the Hall element 19. In FIG. 9, the magnitude of the magnetic field in the vicinity of the position P where the peak of the magnetic field is seen is close to the magnitude of the permanent magnet disposed above the Hall element 19. Therefore, it is considered that the superconducting wire 20 near the position P has a defect. That is, the presence or absence of a defect in the superconducting wire 20 can be detected by detecting the change in the magnetic field with respect to the position of the superconducting wire 20 by the Hall element unit 6.

  Next, when the measurement of the magnetic field is completed, the movement of the superconducting wire 20 is stopped as shown in FIG. 7 (step S3: FIG. 6). With the superconducting wire 20 stopped, the critical current measuring unit 2 measures the critical current value of the portion of the superconducting wire 20 in which the presence or absence of a defect is detected in the hall element unit 6 on the upstream side 7 (step S4: FIG. 6). In the measurement of the critical current value, the voltage when the current is passed through the section to be measured 3 by the current source 15 is measured by the voltmeter 14, whereby the critical current value is measured.

Here, a method for measuring the critical current value of the superconducting wire 20 will be described.
The critical current value is the maximum current value that can be passed through the superconductor. In an ideal superconductor, the resistance value is 0, so the voltage is 0 even when a current is passed. However, in the actual superconducting wire 20, a slight voltage is detected when a current is passed.

  For example, as shown in FIG. 10, the critical current value can be obtained by measuring a voltage when a current is passed through the measured section 3. The value of the current passed through the measured section 3 can be gradually changed from a low value to a high value. The voltage for each current value is plotted as shown in FIG. As the current value is gradually increased, the voltage suddenly increases. A threshold value of a reference voltage (reference voltage indicated by a dotted line) is determined, and a current that becomes the threshold voltage is determined as a critical current (Ic).

  After the measurement of the critical current value is completed, the superconducting wire 20 is moved to the downstream side 8 as shown in FIG. 1 (step S5: FIG. 6). In a state where the superconducting wire 20 is moving, the magnetic field changed by the superconducting wire 20 is measured by the hall element portion 6 on the downstream side 8 (step S6: FIG. 6). The presence or absence of a defect in the superconducting wire 20 is detected by measuring the magnetic field of the Hall element section 6 on the downstream side 8.

  As described above, the method for measuring the critical current of the superconducting wire 20 according to the first embodiment includes the step of measuring the critical current value and the step of detecting defects by measuring the magnetic field.

  The step of measuring the critical current value is performed by measuring the voltage in the measured section 3 by bringing the voltage electrodes 4 and 4 into contact with both ends of the measured section 3 extending along the longitudinal direction X of the superconducting wire 20. .

  In the step of measuring the magnetic field, the magnetic field changed by the superconducting wire 20 by the Hall element unit 6 arranged at least one of the upstream side (one side) and the downstream side (the other side) in the longitudinal direction with respect to the section 3 to be measured. Done by measuring.

  Next, the effects of the critical current measuring apparatus 1 and the critical current measuring method for the superconducting wire 20 of the first embodiment will be described.

  According to the critical current measuring device 1 and the critical current measuring method according to the first embodiment, the defect detection of the superconducting wire 20 is performed by the Hall element unit 6. Since the Hall element unit 6 can detect a defect in the superconducting wire 20 while relatively moving the superconducting wire 20 without contacting the superconducting wire 20, the defect in the superconducting wire 20 can be detected in a short time. The critical current measurement unit 2 can also measure the critical current of the superconducting wire 20. Therefore, the measurement time of the critical current value of the superconducting wire 20 when viewed in total can be shortened.

  Further, according to the critical current measuring device 1 having the Hall element portion 6 on the downstream side 8 and the critical current measuring method using the Hall element portion 6 provided on the downstream side 8, the critical current of the superconducting wire 20 is measured and then downstream. The presence / absence of defects in the superconducting wire 20 can be detected by the Hall element portion 6 on the side 8. When the voltage electrodes 4, 4 and the current electrodes 5, 5 are pressed against the superconducting wire 20 in order to measure the critical current value, the superconducting wire 20 may be damaged. The presence or absence of a defect in the superconducting wire 20 damaged by the critical current measurement can be detected by the hall element portion 6 on the downstream side 8.

  Further, according to the critical current measuring device 1 having the Hall element portion 6 provided on the upstream side 7 and the critical current measuring method using the Hall element portion 6 provided on the upstream side 7, the critical current of the superconducting wire 20 is measured. Before the detection, the presence or absence of a defect in the superconducting wire 20 can be detected by the Hall element portion 6 provided on the upstream side 7. Therefore, by using the information on the presence / absence of defects in the superconducting wire 20, it is possible to efficiently determine the section in which the critical current value is measured. For example, when the section to be measured 3 with the superconducting wire 20 has a defect, the section to be measured 3 can be finely divided to check in detail where and how many defects are present. On the other hand, when the superconducting wire 20 has no defect, the critical current value in the section to be measured 3 is measured only once. Thereby, the measurement time of a total critical current value can be shortened. In addition, since it is possible to determine whether the critical current measuring section is to be a long section or a short section by using information on the presence or absence of defects in the superconducting wire, it has defects and must be discarded. Since the amount of superconducting wires can be reduced, the yield of superconducting wires is improved.

  In addition, as shown in FIG. 4, when the Hall element section 6 has a plurality of Hall elements 19 arranged in the longitudinal direction X of the superconducting wire 20, for example, one Hall element 19 is caused by suddenly generated noise. Even when the magnetic field changed by the superconducting wire 20 cannot be measured accurately, the defects of the superconducting wire 20 can be accurately detected by the other Hall elements 19.

  In addition, as shown in FIG. 5, when the Hall element section 6 has a plurality of Hall elements 19 arranged in the width direction Y of the superconducting wire 20, the magnetic field distribution in the width direction Y of the superconducting wire 20 is measured. Therefore, it is possible to detect in which part in the width direction Y of the superconducting wire 20 the defect exists, and to detect the defect of the superconducting wire 20 with higher accuracy.

In addition, as shown in FIG. 5, the Hall element portion 6 includes a plurality of Hall elements 19 arranged in the width direction Y, whereby information on the current density J of the superconducting wire 20 can be obtained. That is, according to the Maxwell equation shown in Formula (1), it can be seen that the value obtained by differentiating the magnetic flux density B by the distance x is proportional to the current density J. Here, B is the magnetic flux density, x is the distance in the width direction, J is the current density, and μ ₀ is the vacuum permeability. In other words, the amount of change in the magnetic flux density B when moving the distance x in the width direction Y is proportional to the current density J. Thereby, the information of the current density J of the superconducting wire 20 can be obtained by obtaining the distribution of the magnetic flux density B in the width direction Y by the Hall element 19 arranged in the width direction of the superconducting wire 20.

(Embodiment 2)
Next, the configuration of the superconducting wire critical current measuring apparatus according to Embodiment 2 of the present invention will be described with reference to FIG.

  As shown in FIG. 7, the configuration of the second embodiment is different from the configuration of the first embodiment in that the critical current measurement unit 2 has a short section measurement unit 18. The short section measuring unit 18 is provided so as to be able to measure voltages of a plurality of short sections located in the measured section 3, and is provided so as to be able to measure critical current values of the plurality of short sections. The short section measurement unit 18 mainly includes a pair of voltage electrodes 41 and 42 and a voltmeter 141. The voltage in the section (short section 1) sandwiched between the pair of voltage electrodes 41 and 42 is provided by the voltmeter 141, and the critical current value in the short section 1 can be measured. Further, a voltage in a short section (short section 2) sandwiched between the voltage electrodes 42 and 43 is provided so as to be measured by the voltmeter 142, and a critical current value in the short section 2 can be measured. A current source 15 and electrodes 5 and 5 are provided so that current flows in the short section 1 and the short section 2.

  Since the configuration of the second embodiment other than this is the same as the configuration of the first embodiment described above, the same elements are denoted by the same reference numerals, and the description thereof will not be repeated.

  Next, a method for measuring the critical current of superconducting wire 20 according to the second embodiment will be described with reference to FIGS.

  As shown in FIGS. 7 and 8, the magnetic field changed by the superconducting wire 20 is measured by the hall element 6 while the superconducting wire 20 is moved by the feed roller 9 and the receiving roller 11 (step S <b> 10: FIG. 8). Whether or not the superconducting wire 20 has a defect is determined based on the value of the magnetic field measured by the Hall element section 6 (step S11: FIG. 8).

  As a result of the magnetic field measurement, when it is determined that the superconducting wire 20 has no defect (no defect), the critical current value of a predetermined long section of the superconducting wire 20 is measured (S14). On the other hand, when it is determined that a part of the superconducting wire 20 is defective, the critical currents of a plurality of short sections located in the section to be measured 3 are measured. For example, the critical current value of the short section 1 which is a part of the measured section 3 is measured (S12). Next, a critical current value in a short section 2 which is a part of the measured section 3 and is different from the short section 1 is measured (S13). For example, when the critical current value in the short section 1 is normal and the critical current value in the short section 2 is abnormal, only the short section 2 is discarded, and the short section 1 is not discarded.

  After the critical current value of the superconducting wire 20 is measured, the superconducting wire 20 is moved in the longitudinal direction X (S15). Then, the critical current value of the next measured section 3 is measured.

  Next, functions and effects of the critical current measuring device 1 and the critical current measuring method for the superconducting wire 20 according to the second embodiment will be described.

  According to the critical current measuring apparatus 1 and the critical current measuring method for the superconducting wire 20 according to the second embodiment, the critical current value of the superconducting wire 20 in a shorter section can be measured. Further, when the Hall element section 6 is provided on the upstream side 7, before the critical current value of the section to be measured 3 is measured, whether the section to be measured 3 has a defect in advance by the Hall element section 6 on the upstream side 7 or not. Can know. If it is determined by the hall element section 6 on the upstream side 7 that a part of the section to be measured 3 has a defect, the short section measuring section 18 is used to make the criticality for each short section in more detail. The current value is measured. Thereby, it is possible to distinguish which short section among the plurality of short sections located in the measured section 3 has a defect and which short section has no defect. Thereby, the quantity of the superconducting wire 20 which has a defect and needs to be discarded can be reduced.

  In the method of measuring the critical current value of the superconducting wire 20 and determining the presence or absence of a defect in the superconducting wire 20 as in the conventional method, when the superconducting wire 20 has a defect, the superconducting wire of a long section is used. After measuring the critical current value of 20, for example, it was necessary to measure the critical current value of the superconducting wire 20 in two short sections. On the other hand, according to the critical current measuring device 1 and the critical current measuring method for the superconducting wire 20 according to the second embodiment, since the presence or absence of a defect in the superconducting wire 20 is determined in advance by the Hall element unit 6, There is no need to measure the superconducting wire 20, and it is only necessary to measure the superconducting wire 20 in two short sections, for example. That is, since the critical current measuring device 1 and the critical current measuring method for the superconducting wire 20 according to the second embodiment can reduce the measurement of the critical current value once compared with the conventional devices and methods, the superconducting wire The total critical current measurement time of 20 can be shortened.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention can be suitably used for a superconducting wire critical current measuring device and a critical current measuring method.

  DESCRIPTION OF SYMBOLS 1 Superconducting wire critical current measuring device, 2 Critical current measuring part, 3 to-be-measured section, 4 Voltage terminal, 5 Current terminal, 6 Hall element part, 7 Upstream side, 8 Downstream side, 9 Feeding roller, 11 Receiving roller, 12 Liquid nitrogen container, 13 Liquid nitrogen, 14 Voltmeter, 15 Current source, 16 PC, 17 Measuring device part, 18 Short section measuring part, 19 Hall element, 20 Superconducting wire, 141, 142 Voltmeter.

Claims (8)

A critical current measuring unit for measuring a critical current value of the measured section by measuring a voltage in contact with both ends of the measured section extending along the longitudinal direction of the superconducting wire;
A Hall element unit for measuring a magnetic field that is disposed on at least one of the one side and the other side in the longitudinal direction from the section to be measured and that is changed by the superconducting wire ;
A moving device for moving the superconducting wire in the longitudinal direction,
The Hall element unit is a critical current measuring device for a superconducting wire, including a downstream Hall element unit arranged downstream of the section to be measured in the moving direction of the superconducting wire by the moving device. The Hall element unit, comprising said upstream Hall element located upstream of the measured interval in the moving direction of the superconducting wire by the moving device, superconducting wire critical current measurement apparatus according to claim 1 .   The critical current measuring unit includes a plurality of short section measuring units capable of measuring a critical current value by measuring voltages of a plurality of short sections located in the measured section. The critical current measuring device of the described superconducting wire. The Hall element unit includes the one side and the other side of the plurality of arranged in the longitudinal direction of the superconducting wire at least one Hall element, the critical superconducting wire according to any one of claims 1 to 3 Current measuring device. The critical current of the superconducting wire according to any one of claims 1 to 3 , wherein the Hall element portion includes a plurality of Hall elements arranged in the width direction of the superconducting wire on at least one of the one side and the other side. measuring device. A step of measuring a critical current value by measuring the voltage of the section to be measured by bringing electrodes into contact with both ends of the section to be measured extending along the longitudinal direction of the superconducting wire; and
A step of measuring a magnetic field changed by the superconducting wire by a Hall element portion arranged on at least one of the one side and the other side in the longitudinal direction from the section to be measured ;
A step of moving the superconducting wire in the longitudinal direction between the step of measuring the critical current value and the step of measuring the magnetic field;
The Hall element portion includes a downstream Hall element portion positioned on the downstream side in the moving direction of the superconducting wire with respect to the measured section.
The step of measuring the magnetic field includes the step of measuring the magnetic field changed by the superconducting wire in the downstream Hall element portion,
A method for measuring a critical current of a superconducting wire , wherein a step of measuring the critical current value is performed before measuring a magnetic field in the downstream Hall element section . The Hall element portion includes an upstream Hall element portion located on the upstream side in the moving direction of the superconducting wire with respect to the section to be measured,
The step of measuring the magnetic field includes the step of measuring the magnetic field changed by the superconducting wire at the upstream Hall element portion,
The method for measuring a critical current of a superconducting wire according to claim 6 , wherein the step of measuring the critical current value is performed after measuring the magnetic field at the upstream Hall element portion. The step of measuring the critical current value measures the critical current value of each of the plurality of short sections by measuring the voltage of each of the plurality of short sections located within the section to be measured of the superconducting wire. A method for measuring a critical current of a superconducting wire according to claim 6 , comprising a step capable of

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