JP2016058608A - High temperature superconducting current lead - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high temperature superconducting current lead excellent in cooling efficiency and durability at the time of overcurrent that can suppress heat generation of a superconducting wire rod by cooling it effectively, and can prevent impairment due to heat generation even if a rating current or more is conducted.SOLUTION: In a high temperature superconducting current lead 1 housed in a vacuum container, together with a high temperature superconducting coil operating in a cryogenic region, having one end side for connection with an external power supply via a current lead and the other end side for connection with the high temperature superconducting coil, and supplying an excitation current to the high temperature superconducting coil, a high temperature superconducting wire rod 3 is laminated on at least a base material 2 composed of high purity aluminum.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a high temperature superconducting current lead for supplying an exciting current to a high temperature superconducting coil operated at a cryogenic temperature.

  For example, a high-temperature superconducting magnet in which a high-temperature superconducting coil is housed in a vacuum vessel and used in a very low temperature region is generally energized constantly from an excitation power source and operates as a magnetic field generator. For this reason, the current lead that supplies the exciting current to the high-temperature superconducting coil is required to have low heat generation and high reliability.

  As described above, the current leads for supplying current to the high-temperature superconducting coil include, for example, a high-temperature superconducting current lead made of an oxide-based superconducting wire and a low-temperature superconducting current lead made of a metal-based superconducting wire. It has been proposed (see, for example, Patent Document 1). The current lead described in Patent Document 1 is configured such that the low temperature end of the high temperature side superconducting current lead is connected to one end of the low temperature side superconducting current lead, and the other end of the low temperature side superconducting current lead is connected to the high temperature superconducting coil. ing.

  In addition, a current lead made of an oxide-based superconducting wire is used for a low-temperature superconducting current lead connected to a high-temperature superconducting coil (see, for example, Patent Document 2). Such an oxide-based superconducting wire has a higher critical temperature and lower thermal conductivity than a metal-based superconducting wire, and therefore, as a material for a current lead that supplies an exciting current to a high-temperature superconducting coil operated in a cryogenic temperature range, This is preferable from the viewpoint of suppressing heat generation.

JP-A-11-340027 JP 2013-175293 A

  However, the superconducting wire as described above, for example, because the critical current decreases as the temperature becomes higher, or when the current is energized at a temperature condition higher than the rated temperature, or when energized in an insufficiently cooled state, There was a risk of sudden heat generation and damage to the current lead itself.

  The present invention has been made in view of the above problems, and can effectively suppress the heat generation of the superconducting wire by cooling the superconducting wire, and generate heat even when a current exceeding the rating is energized. An object of the present invention is to provide a high-temperature superconducting current lead that can prevent damage due to heat and has excellent cooling efficiency and durability during overcurrent.

  In order to solve the above problems, a high-temperature superconducting current lead according to the present invention is housed in a vacuum vessel together with a high-temperature superconducting coil that operates in a cryogenic region, and one end side is connected to an external power source via a current lead, The other end side is connected to the high-temperature superconducting coil, thereby being a high-temperature superconducting current lead for supplying an exciting current to the high-temperature superconducting coil, and a high-temperature superconducting wire is laminated on a substrate made of at least high-purity aluminum It is characterized by becoming.

  According to the high-temperature superconducting current lead having such a configuration, since the high-temperature superconducting wire is laminated on the base material made of high-purity aluminum having high thermal conductivity, the cooling plate on which the high-temperature superconducting current lead is installed Since the cooling heat is effectively transmitted to the high-temperature superconducting wire through the base material, the high-temperature superconducting wire can be stably cooled. Furthermore, since the high-purity aluminum that forms the base material has high electrical conductivity, even when a current exceeding the rated current is applied to the high-temperature superconducting wire, this current is shunted to the base material side, so the high-temperature superconducting wire Is prevented from generating heat, and damage to the high-temperature superconducting wire can be prevented. Accordingly, it is possible to provide a high-temperature superconducting current lead having excellent cooling efficiency and durability during overcurrent.

  Further, the high-temperature superconducting current lead according to the present invention has a laminated structure in which the base material is bonded to the cooling substrate made of high-purity aluminum and the joining substrate made of oxygen-free copper by the explosion method in the above-described configuration. It is preferable to adopt a configuration in which the high-temperature superconducting wire is joined to the joining substrate by soldering.

  According to the high-temperature superconducting current lead having such a configuration, since the base material is a configuration in which a bonding substrate made of oxygen-free copper is exploded on a cooling substrate made of high-purity aluminum, the high-temperature superconducting wire is formed on the bonding substrate. Can be joined by soldering. Usually, since an oxide film is formed on the surface of an aluminum material, a high-temperature superconducting wire cannot be joined by a general soldering method. Thus, soldering onto a bonding substrate made of oxygen-free copper can be performed. Therefore, in addition to the improvement of the cooling efficiency and the durability at the time of overcurrent as described above, the effect of improving the productivity can be obtained.

  In the high-temperature superconducting current lead according to the present invention, in the above configuration, the high-purity aluminum forming the base material is more preferably high-purity aluminum having a purity of 99.99% or more.

  According to the high-temperature superconducting current lead having such a configuration, the high-purity aluminum used for the base material is made to have a very high purity as described above, so that the thermal conductivity and the electrical conductivity are further increased. Therefore, the cooling efficiency of the high-temperature superconducting wire as described above is further improved, and when a current exceeding the rating is applied to the high-temperature superconducting wire, the current can be more effectively diverted to the substrate side. Therefore, an effect of further improving the cooling efficiency and durability at the time of overcurrent as described above can be obtained.

According to the high-temperature superconducting current lead according to the present invention, as described above, the high-temperature superconducting wire is laminated on a base material made of high-purity aluminum having a high thermal conductivity. Therefore, the high-temperature superconducting current lead is installed. Since the cooling heat from the cooling plate is effectively transmitted to the high-temperature superconducting wire through the base material, the high-temperature superconducting wire can be stably cooled. Furthermore, since the high-purity aluminum that forms the base material has high electrical conductivity, even when a current exceeding the rated current is applied to the high-temperature superconducting wire, this current is shunted to the base material side, so the high-temperature superconducting wire Is prevented from generating heat, and damage to the high-temperature superconducting wire can be prevented.
Accordingly, it is possible to provide a high-temperature superconducting current lead having excellent cooling efficiency and durability during overcurrent.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram schematically illustrating a high-temperature superconducting current lead according to an embodiment of the present invention, and a high-temperature superconducting wire on a base material in which a cooling substrate made of high-purity aluminum and a bonding substrate made of oxygen-free copper are joined. It is a perspective view which shows the structure where was laminated | stacked. It is the schematic explaining the case where the high temperature superconducting current | flow lead which is one Embodiment of this invention is applied to the supply means of the exciting current to the high temperature superconducting coil accommodated in the vacuum vessel. It is a figure explaining the Example of the high temperature superconducting current lead which is one embodiment of the present invention, and is a schematic diagram showing the circuit configuration of the test apparatus used when measuring the voltage between each end of the high temperature superconducting current lead. is there. It is a figure explaining the Example of the high-temperature superconducting current lead which is one embodiment of the present invention, and shows the relationship between the current applied to the high-temperature superconducting current lead and the voltage between the ends measured by the circuit shown in FIG. It is a graph to show. It is a figure explaining the Example of the high-temperature superconducting current lead which is one embodiment of the present invention, and the excess current from the critical current (280A) of the high-temperature superconducting current lead and each end per unit length of the high-temperature superconducting current lead It is a graph which shows the relationship with the voltage between parts.

  Hereinafter, an example of the high-temperature superconducting current lead that is an embodiment of the present invention will be given, and its configuration and operation will be described in detail with reference to FIGS. 1 and 2 as appropriate. In addition, each drawing used in the following description may show the characteristic part in an enlarged manner for convenience in order to make the feature easy to understand, and the dimensional ratio of each component is different from the actual case. There is. In addition, the materials, dimensions, and the like exemplified in the following description are examples, and the present invention is not limited to them, and can be appropriately changed and implemented without changing the gist thereof.

  FIG. 1 is a perspective view for explaining a laminated structure of the high-temperature superconducting current lead 1 of this embodiment. FIG. 2 is a high-temperature superconducting coil in which the high-temperature superconducting current lead 1 of this embodiment is accommodated in a vacuum vessel 11. 12 is a schematic diagram showing a configuration of a high-temperature superconducting magnet 10 used as means for supplying an exciting current to 12. FIG. As shown in FIG. 2, the high-temperature superconducting current lead 1 of the present embodiment is installed on a cooling plate 14 cooled by a refrigerator 13 and supplies an excitation current to the high-temperature superconducting coil 12 from the outside.

  As shown in FIG. 1, the high-temperature superconducting current lead 1 of the present embodiment has a laminated structure in which a cooling substrate 21 made of high-purity aluminum and a bonding substrate 22 made of oxygen-free copper are bonded by an explosion method. 2 is schematically configured as a long wire in which a high-temperature superconducting wire 3 is laminated. The high-temperature superconducting current lead 1 is configured such that the high-temperature superconducting wire 3 is joined to the upper surface 2a of the base material 2, that is, the joining substrate 22, by soldering.

  The base material 2 has a long plate shape in plan view, and a high-temperature superconducting wire 3 to be described in detail later is laminated on the upper surface 2a side. In the illustrated example, the horizontal width dimension is configured to be slightly larger than that of the high-temperature superconducting wire 3. Moreover, the lower surface 2b side of the base material 2, that is, the lower surface side of the cooling substrate 21, serves as an installation surface for the cooling plate 14 provided in the high-temperature superconducting magnet 10 described later in detail.

  As described above, the cooling substrate 21 is made of high-purity aluminum and thus has high thermal conductivity and electrical conductivity. Thereby, the cooling substrate 21 can efficiently transmit the cooling heat from the cooling plate 14 provided in the high temperature superconducting magnet 10 shown in FIG. 2 toward the high temperature superconducting wire 3 side.

  The high-purity aluminum used for the cooling substrate 21 is preferably as high as possible and is particularly preferably high-purity aluminum having a purity of 99.99% or more. In this way, by configuring the cooling substrate 21 from high-purity aluminum having a purity of 99.99% or more, not only the cooling substrate 21 but also the overall thermal conductivity of the base material 2 is improved, and the electrical conductivity is further increased. It will be expensive.

In FIG. 1, the bonding substrate 22 has the same size and shape in plan view as the cooling substrate 21.
The material of the bonding substrate 22 is preferably a material having high thermal conductivity as in the case of the cooling substrate 21, and for example, oxygen-free copper such as C1020 can be used. Such oxygen-free copper is excellent in thermal conductivity and electrical conductivity as in the case of high-purity aluminum. Therefore, it is possible to efficiently transmit cooling heat toward the high-temperature superconducting wire 3, and the high-temperature superconducting wire 3. When a current exceeding the rating is applied to the current, the current can be effectively diverted to the substrate 2 side.

  The base material 2 has a laminated structure in which the cooling substrate 21 and the bonding substrate 22 are surface-bonded by an explosion bonding method. Thus, when joining the cooling substrate 21 and the joining substrate 22 which are made of different metals, it is preferable to use an blasting method using dynamite in consideration of the joining strength and the like. As the explosive deposition conditions at this time, the conditions conventionally employed when joining an aluminum material and a copper material can be used without any limitation.

  In this embodiment, the base material 2 employs a configuration in which a bonding substrate 22 made of oxygen-free copper is laminated on a cooling substrate 21 made of high-purity aluminum. In joining on the material 2, joining by soldering onto the joining substrate 22 becomes possible.

  In addition, although it does not specifically limit as each thickness of the cooling substrate 21 and the joining board | substrate 22 which comprise the base material 2, and the thickness of the base material 2 whole, The size at the time of comprising the high temperature superconducting current | flow lead 1 of this embodiment. For example, the thickness of the cooling substrate 21 can be 4 to 7 mm, the thickness of the bonding substrate 22 can be 1 to 3 mm, and the total thickness of the base material 2 can be 5 to 10 mm. Similarly, with respect to the width dimension of the base material 2, that is, the width dimensions of the cooling substrate 21 and the bonding substrate 22 constituting the base material 2, the size and thermal conductivity when the high-temperature superconducting current lead 1 is constructed are taken into consideration. However, it may be determined appropriately.

  The high-temperature superconducting wire 3 is a wire made of a high-temperature superconducting material. In FIG. 1, like the base material 2, the high-temperature superconducting wire 3 is formed in a long plate shape in plan view, and the width direction dimension is the base material 2. That is, it is configured to be slightly narrower than the cooling substrate 21 and the bonding substrate 22. Thus, the high-temperature superconducting current lead 1 is configured such that the bonding substrate 22 of the base material 2 is exposed from both sides in the width direction of the high-temperature superconducting wire 3 when viewed in plan.

The high-temperature superconducting wire 3 used for the high-temperature superconducting current lead 1 of the present embodiment is made of, for example, an oxide-based superconducting material and has a heat resistance of about 300 ° C.
More specifically, the high-temperature superconducting wire 3 is not shown in detail, but, for example, a superconducting layer is laminated on a base material made of metal via an intermediate layer, and a stabilization layer is further formed thereon. And a structure in which protective layers are sequentially laminated.

  As the base material of the high-temperature superconducting wire 3, for example, a substrate in which a substrate made of an alloy material such as Ni-W alloy or Hastelloy (registered trademark) is laminated on Cu can be used.

In the high-temperature superconducting wire 3, as the intermediate layer interposed between the base material and the superconducting layer, for example, one having a composition and a laminated structure of Y ₂ O ₃ / YSZ / CeO ₂ can be adopted. A method for laminating the intermediate layer having such a composition on a base material made of metal is not particularly limited, and a conventionally known method such as a vapor deposition method (CVD method) or a sputtering method can be used. .

In the high-temperature superconducting wire 3, the superconducting layer provided on the intermediate layer has a high critical temperature such as REBa ₂ Cu ₃ O _x (RE: Rare Earth (rare earth element)), bismuth-based superconducting layer, and the like. An oxide-based superconducting material having a small thermal conductivity can be employed. A method of laminating the superconducting layer having such a composition on the intermediate layer is not particularly limited, and for example, a conventionally known method such as a PLD (Pulse Laser Deposition) method can be used.

In the high-temperature superconducting wire 3, for example, an Ag material can be used as the stabilizing layer laminated on the superconducting layer.
Furthermore, as the protective layer of the high-temperature superconducting wire 3 laminated on the stabilization layer, for example, a Cu material can be used.
In forming these stabilizing layers and protective layers, for example, a conventionally known sputtering method or the like can be used.

  Here, the thickness of the high-temperature superconducting wire 3 and the thickness of each of the layers constituting the high-temperature superconducting wire 3 are not particularly limited, but the size and electrical characteristics when the high-temperature superconducting current lead 1 is constructed are taken into consideration. For example, the thickness of the substrate is 50 to 100 μm, the thickness of the intermediate layer is 1 to 2 μm, the thickness of the superconducting layer is 1 to 6 μm, the thickness of the protective layer is 1 to 5 μm, and the thickness of the stabilization layer is 40 to 100 μm. The overall thickness of the high-temperature superconducting wire 3 can be in the range of 0.1 to 0.2 μm. Similarly, the width dimension of the high-temperature superconducting wire 3 may be appropriately determined in consideration of the electrical characteristics when the high-temperature superconducting current lead 1 is configured.

  Further, the high-temperature superconducting wire used for the high-temperature superconducting current lead 1 of the present embodiment is not limited to a plate in which each layer is laminated as in the above configuration. For example, as described in Japanese Patent Application Laid-Open No. 2012-14883 (Japanese Patent Application No. 2010-148409) by the present applicant, a base material, an intermediate layer, a superconducting layer, and a stabilization layer are covered so as to cover a metal base material serving as a shaft material. It is also possible to employ a high-temperature superconducting wire having a configuration in which the protective layer and the protective layer are sequentially laminated and the cross-section is polygonal.

  In the high-temperature superconducting current lead 1 described in the present embodiment, the base material side (not shown) of the high-temperature superconducting wire 3, that is, the lower surface 3 a shown in FIG. 1 is on the upper surface 2 a (bonding substrate 22) of the base material 2. As a result, the high-temperature superconducting wire 3 is joined to the base material 2. The solder material used at this time is not particularly limited, but a low melting point solder material is preferably used.

  As described above, the high-temperature superconducting current lead 1 of the present embodiment has a configuration in which the high-temperature superconducting wire 3 is laminated on the base material 2 made of high-purity aluminum having high thermal conductivity and high electrical conductivity. Specifically, the high-temperature superconducting current lead 1 has a base material 2 in which a cooling substrate 21 made of high-purity aluminum and a bonding substrate 22 made of oxygen-free copper are laminated, and the high-temperature superconducting wire rod is formed on the bonding substrate 22. 3 is laminated. Thereby, the cooling heat from the cooling plate 14 of the high-temperature superconducting magnet 10 on which the high-temperature superconducting current lead 1 is installed is effectively transmitted to the high-temperature superconducting wire 3 through the base material 2, so that the high-temperature superconducting wire 3 is stable. The effect of being cooled is obtained. Furthermore, since high-purity aluminum has a high electrical conductivity, even when a current exceeding the rated current is passed through the high-temperature superconducting wire 3, the current is shunted to the substrate 2 side, whereby the high-temperature superconducting wire 3 Therefore, the effect of reliably preventing damage to the high-temperature superconducting wire 3 can be obtained.

  Here, as the high-temperature superconducting current lead, the base material 2 may be composed only of the cooling substrate 21 made of high-purity aluminum, and the high-temperature superconducting wire 3 to be described later may be joined to the cooling substrate 21. On the other hand, in such a case, when joining the high temperature superconducting wire 3 to the base material 2, it is necessary to consider a method other than soldering. For this reason, in this embodiment, as shown in FIG. 1, the base material 2 has a configuration in which a bonding substrate 22 made of oxygen-free copper is laminated on a cooling substrate 21 made of high-purity aluminum. preferable. As a result, the high-temperature superconducting wire 3 can be joined to the joining substrate 22 disposed on the upper surface 2a side of the base material 2 by soldering, so that the above-described cooling efficiency and durability during overcurrent can be achieved. In addition to the improvement, the productivity can be improved and the manufacturing cost can be reduced.

Next, the high-temperature superconducting magnet 10 provided with the high-temperature superconducting current lead 1 of the present embodiment will be described with reference to FIG.
As shown in FIG. 2, the high-temperature superconducting magnet 10 includes a high-temperature superconducting coil 12, a refrigerator 13, and a cooling plate 14 housed in a vacuum vessel 11. In the illustrated example, the high-temperature superconducting current lead 1 of this embodiment and a part of the current lead 15 that conducts current from the outside to the high-temperature superconducting current lead 1 are installed in the vacuum vessel 11, and the high-temperature superconducting current lead 1 is heated from the outside. The exciting current can be supplied to the superconducting coil 12. In the illustrated example, one end side 1 a of the high-temperature superconducting current lead 1 is connected to an external power source (not shown) via a current lead 15, and the other end side 1 b is connected to the high-temperature superconducting coil 12. In addition, the high-temperature superconducting current lead 1 is installed on a cooling plate 14 cooled by the refrigerator 13 via a material that enhances adhesion, such as grease or a metal material, and the lower surface 2b of the substrate 2; That is, the cooling substrate 21 side is installed on the cooling plate 14.

  The vacuum vessel 11 accommodates the main components of the high-temperature superconducting magnet 10 in the internal space. For example, the internal space is depressurized by a vacuum pump (not shown). In the illustrated vacuum vessel 11, the high temperature superconducting current lead 1, the high temperature superconducting coil 12, the refrigerator 13, the cooling plate 14 and a part of the current lead 15 are accommodated inside the container body 11a, and the opening thereof is formed. It is set as the structure covered with the container cover part 11b.

  The high-temperature superconducting coil 12 generates a strong magnetic force as the high-temperature superconducting magnet 10 when an excitation current is supplied from the outside by the current lead 15 and the high-temperature superconducting current lead 1. Further, the high temperature superconducting coil 12 is installed on the cooling plate 14 as shown in the drawing.

  The refrigerator 13 is constituted by, for example, a conventionally known compressor or the like, and is thermally and mechanically connected to a later-described cooling plate 14. The refrigerator 13 cools the high-temperature superconducting coil 12 and the high-temperature superconducting current lead 1 installed on the cooling plate 14 to a cryogenic temperature region of −200 ° C. or lower, for example, by cooling the cooling plate 14. .

  As shown in the illustrated example, the cooling plate (cold head) 14 is a flat plate-like member installed substantially downward in the internal space of the vacuum vessel 11 and is made of, for example, a metal material having high thermal conductivity. As described above, the cooling plate 14 is cooled to a cryogenic temperature region by connecting the refrigerator 13 to the upper surface side thereof, and thereby the high temperature superconducting coil 12 and the high temperature superconducting current lead 1 installed on the upper surface side. Cool each to a cryogenic temperature range.

  The current lead 15 has one end side 15a connected to one end side 1a of the high-temperature superconducting current lead 1 and the other end side connected to an external power supply (not shown), so that an excitation current supplied from the outside can be supplied to the high-temperature superconducting current lead. 1 is configured so that it can be supplied to the high-temperature superconducting coil 12 via 1.

  In the example shown in FIG. 2, the current lead 15 is shown on both the positive electrode (+) side and the negative electrode (−) side, but the high-temperature superconducting current lead 1 is installed on the cooling plate 14. Only one of them is shown in the figure because it is in a state of being performed.

  As described above, the high-temperature superconducting current lead 1 of the present embodiment is installed on the cooling plate 14 on the side of the cooling substrate 21 made of high-purity aluminum, so that the high-temperature superconducting wire is generated by the cooling heat transmitted through the base material 2. Since 3 is cooled stably, the heat generation of the high temperature superconducting wire 3 can be effectively suppressed, and the high temperature superconducting wire 3 can be reliably prevented from being damaged.

  Next, the present invention will be described in detail by the following examples, but the present invention is not limited only to these examples.

[Example 1]
In Example 1, a high-temperature superconducting current lead as shown in FIG. 1 was manufactured under the conditions and procedures shown below, and then a test apparatus having a circuit configuration as shown in FIG. 3 was prepared. The voltage between each end was measured.

  First, a bonded substrate made of oxygen-free copper is bonded to a cooling substrate made of high-purity aluminum having a purity of 99.99% or more by a blasting method using dynamite, having a length of 200 mm, a width of 100 mm, A base material having a thickness of 41 mm (oxygen-free copper 4 mm) was prepared. And after rolling this base material, by cutting out to a predetermined size, the length is 600 mm, the width is 12 mm, the thickness is 7 mm in plan view, and the bonding substrate 22 is bonded onto the cooling substrate 21. A base material 2 was obtained.

  Further, as the high-temperature superconducting wire 3, 2 G HTS WIRE (registered trademark) manufactured by SuperPower is used, and the wire is cut into a predetermined size so that the length is 600 mm, the width is 6 mm, and the thickness is 0.1 mm. I prepared a dish.

Then, the high-temperature superconducting wire 3 obtained by the above method was soldered onto the bonding substrate 22 of the base material 2 with the unillustrated base material side of the high-temperature superconducting wire 3 as the bottom surface. At this time, the entire surface was soldered between the high temperature superconducting wire 3 and the bonding substrate 22 of the base material 2 using a low melting point solder material.
Under the conditions and procedures as described above, a high-temperature superconducting current lead 1 of this example as shown in FIG. 1 was obtained.

  Next, a test apparatus having a circuit configuration as shown in FIG. 3 was prepared using the high-temperature superconducting current lead 1 obtained by the above procedure, and the voltage between each end of the high-temperature superconducting current lead 1 was measured. In this test apparatus, two high-temperature superconducting current leads 1 are arranged and bonded in parallel using an insulating adhesive film (not shown) on an aluminum plate, and one end side thereof is short-circuited to form a series circuit. In addition, a power supply (not shown) is connected to the other end side so that a current can be supplied. Further, a voltmeter for measuring a voltage between one end side and the other end side was connected to each of the two high-temperature superconducting current leads 1. Moreover, this apparatus was accommodated in the heat insulation container not shown in figure, and it cooled to 77K (-196 degreeC) by supplying liquid nitrogen in this heat insulation container.

  Then, when one of the high-temperature superconducting current leads 1 is on the plus (+) side and the other high-temperature superconducting current lead 1 is on the minus (−) side, current supply is performed while gradually increasing the current value from 0A. The voltage between both ends of each high-temperature superconducting current lead 1 was measured and these were visually confirmed.

As a test result of Example 1, the relationship between the current applied to the high-temperature superconducting current lead and the voltage between the ends is shown in the graph of FIG.
As shown in FIG. 4, the high-temperature superconducting current lead 1 having the configuration according to the present invention manufactured in this example has a gradual voltage rise curve even when the critical current of the high-temperature superconducting wire exceeds 280A. Stable energization was possible even at 400 A, which greatly exceeded the critical current, and troubles such as damage due to heat generation did not occur.

  In the graph of FIG. 4, the rising curve slightly differs between the plus (+) side and the minus (−) side of the high-temperature superconducting current lead 1 because of a measurement error caused by a loss in each electrical connection portion. it is conceivable that.

[Example 2]
In Example 2, the high-temperature superconducting current lead 1 manufactured in Example 1 and a conventional high-temperature superconducting current lead composed of a single high-temperature superconducting wire were prepared, and one high-temperature superconducting current lead was provided for each of these. The voltage per unit length of the high-temperature superconducting current lead was examined by applying a current gradually to the high-temperature superconducting current lead in the same procedure using the same test apparatus as in Example 1 except for the points evaluated in (1). . As a test result of Example 2, the relationship between the excess current from the critical current (280 A) of the high-temperature superconducting current lead and the voltage per unit length of the high-temperature superconducting current lead is shown in the graph of FIG.

As shown in FIG. 5, the high-temperature superconducting current lead 1 having the configuration according to the present invention produced in Example 1 has an increase in voltage per unit length even when the critical current of the high-temperature superconducting wire exceeds 280A. The curve was gentle.
On the other hand, the high-temperature superconducting current lead having the conventional configuration exhibited a curve characteristic in which the voltage per unit length suddenly increased when the critical current of the high-temperature superconducting current lead exceeded 160A.

  From the results of each of the above examples, the high-temperature superconducting current lead according to the present invention has a gradual voltage rise curve and can be stably energized even when a current exceeding the critical current is applied. Became clear.

  In addition, each structure in those embodiment and each Example demonstrated above, those combinations, etc. are examples, and addition, omission, substitution, and other change of a structure are possible in the range which does not deviate from the meaning of this invention. . Further, the present invention is not limited by the above-described embodiment, and is limited only by the scope of the claims.

  According to the high-temperature superconducting current lead of the present invention, by adopting the above configuration, it is possible to prevent damage due to heat generation even when a current exceeding the rated current is applied, cooling efficiency and durability during overcurrent Therefore, it is very useful in applications where an exciting current is supplied to a high temperature superconducting coil operated at a very low temperature.

DESCRIPTION OF SYMBOLS 1 ... High temperature superconducting electric current lead 2 ... Base material 2a ... Upper surface 2b ... Lower surface 21 ... Cooling substrate 21
DESCRIPTION OF SYMBOLS 22 ... Bonding board 3 ... High temperature superconducting wire 3a ... Lower surface 10 ... High temperature superconducting magnet 11 ... Vacuum container 11a ... Container body 11b ... Container lid part 12 ... High temperature superconducting coil 13 ... Refrigerator 14 ... Cooling plate 15 ... Current lead.

Claims (3)

A high-temperature superconducting coil that is operated in a cryogenic temperature region is housed in a vacuum vessel, and one end side is connected to an external power source via a current lead, and the other end side is connected to the high-temperature superconducting coil, thereby A high temperature superconducting current lead for supplying an exciting current to the coil,
A high-temperature superconducting current lead comprising a high-temperature superconducting wire laminated on a substrate made of at least high-purity aluminum. The base material has a laminated structure in which a cooling substrate made of high-purity aluminum and a bonding substrate made of oxygen-free copper are bonded by an explosion method,
The high-temperature superconducting current lead according to claim 1, wherein the high-temperature superconducting wire is bonded onto the bonding substrate by soldering.   3. The high-temperature superconducting current lead according to claim 1, wherein the high-purity aluminum forming the substrate is high-purity aluminum having a purity of 99.99% or more.

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