JP2012028041A - Superconducting current lead - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a superconducting current lead which electrically connects a high-temperature side and a low-temperature side, uses a superconducting wire rod or superconducting tape wire rod of a low manufacturing cost, and reduces heat amount invading the low-temperature side.SOLUTION: The superconducting current lead includes: a high temperature side electrode terminal 11 provided at one end; a low temperature side electrode terminal 12 provided at the other end; a first lead part 13 provided between the high temperature side electrode terminal 11 and low temperature side electrode terminal 12, and comprising a plurality of first superconducting wire rods W1 connected to one another in parallel; and a second lead part 14 provided between the first lead part 13 and the low temperature side electrode terminal 12 to be connected in series with the first lead part 13, and comprising second superconducting wire rods W2 less in number than the first superconducting wire rods W1.

Description

  The present invention relates to a superconducting current lead using a superconducting wire.

  In a superconducting device such as a superconducting magnet device, a current lead for supplying power to a superconductor such as a superconducting coil is used. For example, in a superconducting magnet device, a power supply source installed on the room temperature side (high temperature side) and a superconducting coil installed on the low temperature side are electrically connected via a current lead.

  A large current is normally passed through the superconducting coil via a current lead. Further, in order to maintain the superconducting state of the superconducting coil, it is necessary to maintain the temperature of the superconducting coil at an extremely low temperature that is not higher than the critical temperature. Therefore, as a current lead, it is common to use a superconductor having an electric resistance close to 0, especially an oxide superconducting material such as a Y-based or Bi-based material having a high critical temperature, so that Joule heat is not generated when a current flows. Is. Hereinafter, a current lead using a superconductor is referred to as a superconducting current lead.

  There is also a large temperature difference between the room temperature side (high temperature side) part where the power supply source is installed and the low temperature side part where the superconducting coil is installed. Due to this temperature difference, heat enters the superconducting coil from the room temperature side (high temperature side) through the current leads.

  Conventionally, as a superconducting current lead using an oxide superconducting material, a bulk superconductor obtained by processing an oxide superconducting material into a bulk shape has been used. However, bulk superconductors require a relatively long time to manufacture them, require relatively advanced technology, and require relatively large manufacturing equipment, so that the manufacturing cost is high. There is.

  Therefore, recently, in order to reduce manufacturing costs, instead of bulk superconductors, superconducting materials were compounded with metal materials that are highly malleable and also have the function of stabilizing the superconducting state of the core wire, and processed into wire rods. Superconducting wires, particularly superconducting tape wires, are becoming increasingly used. Since the superconducting wire or the superconducting tape wire can be manufactured relatively easily, it has an advantage that the manufacturing cost is relatively low as compared with the bulk superconductor.

  However, the superconducting wire or the superconducting tape wire is composed of a core wire made of a superconducting material and a base material made of a metal material. Therefore, if the superconducting wire or the superconducting tape wire is designed so that a current equal to that of the bulk superconductor can flow in the superconducting state, it penetrates from the room temperature side (high temperature side) to the low temperature side through the base material made of a metal material. The amount of heat will increase.

  Therefore, in a superconducting current lead using a superconducting wire or a superconducting tape wire, a superconducting current that reduces the intrusion heat entering the low temperature side by winding the wire or tape wire around a cylindrical support member and lengthening the heat conduction path. There is a lead (see, for example, Patent Documents 1 and 2).

JP 2008-305765 A JP 2009-230912 A

  However, a superconducting current lead that reduces the amount of heat entering the low temperature side by winding a wire or a tape wire and lengthening the heat conduction path as described above has the following problems.

  When winding a wire, a large bending strain is applied to the wire, thereby lowering the value of the critical current. In particular, in the case of a tape wire, by winding the tape wire, a magnetic field is applied perpendicularly to a wide surface (hereinafter referred to as “tape surface”) including a long side of the rectangular shape of the cross section of the tape wire. The value drops.

  The above problem can be avoided if the wire is extended substantially straight without winding a long wire. However, the length of the superconducting current lead becomes very large, and it is difficult to install in various superconducting devices such as a superconducting magnet device, which is unrealistic.

  The present invention has been made in view of the above points, and in a superconducting current lead that electrically connects a high temperature side and a low temperature side, a superconducting wire or a superconducting tape wire having a low manufacturing cost is used and enters the low temperature side. Provided is a superconducting current lead that can reduce the amount of intrusion heat.

  In order to solve the above problems, the present invention is characterized by the following measures.

  The present invention is provided between the high temperature side electrode terminal provided at one end, the low temperature side electrode terminal provided at the other end, the high temperature side electrode terminal and the low temperature side electrode terminal, and in parallel with each other. The first lead portion made of a plurality of connected first superconducting wires, and the first lead portion and the low temperature side electrode terminal are connected in series with the first lead portion. And a second lead portion made of a second superconducting wire whose number is smaller than the number of the first superconducting wires.

  The present invention further includes an intermediate connection terminal for connecting the low temperature side electrode terminal side of the first lead portion and the high temperature side electrode terminal side of the second lead portion in the above-described superconducting current lead. .

  Further, the present invention is the above superconducting current lead, wherein the intermediate connection terminal has a plurality of grooves formed so as to extend from the high temperature side electrode terminal side toward the low temperature side electrode terminal side, Each of the first superconducting wire and the second superconducting wire is embedded in the groove by solder bonding.

  According to the present invention, in the above-described superconducting current lead, the second superconducting wire is composed of a superconducting wire continuous with the first superconducting wire.

  Further, according to the present invention, in the above-described superconducting current lead, the high temperature side electrode terminal side of the first lead portion is connected to the high temperature side electrode terminal, and the high temperature side electrode terminal is connected to the second high temperature side electrode terminal. The connection resistance between the first superconducting wire composed of a superconducting wire that is continuous with the superconducting wire and the high temperature side electrode terminal is composed of a superconducting wire other than the superconducting wire that is continuous with the second superconducting wire. It has a resistance adjustment part for adjusting so that it may become larger than the connection resistance between a 1st superconducting wire and the said high temperature side electrode terminal.

  The present invention further includes a support member that integrally supports the high temperature side electrode terminal and the low temperature side electrode terminal in the superconducting current lead described above.

  Further, according to the present invention, in the above-described superconducting current lead, a difference in thermal expansion coefficient between the support member and the first superconducting wire, and a difference in thermal expansion coefficient between the support member and the second superconducting wire. Is within ± 0.14%.

  Further, the present invention is the above-described superconducting current lead, wherein the superconducting wire is a superconducting tape wire, the first superconducting wire is a first superconducting tape wire, and the second superconducting wire is a first superconducting wire. The superconducting current lead is connected to a high temperature portion in the superconducting magnet device and the low temperature side electrode terminal is connected to a low temperature portion in the superconducting magnet device. The first superconducting tape wire and the second superconducting tape wire are such that the tape surface of the first superconducting tape wire and the tape surface of the second superconducting tape wire are the superconducting magnet device. It is arranged so as to be substantially parallel to the generated magnetic field.

  According to the present invention, in a superconducting current lead that electrically connects a high temperature side and a low temperature side, a superconducting wire or a superconducting tape wire with a low manufacturing cost can be used, and the amount of heat entering the low temperature side can be reduced. .

It is a front view of the superconducting current lead according to the first embodiment. It is a perspective view which expands and shows the vicinity of an intermediate connection terminal. It is sectional drawing of the intermediate | middle connection terminal and superconducting wire which follow the AA line of FIG. It is an equivalent circuit diagram which shows the state of the electrical connection of the 1st lead | read | reed part of the superconducting electric current lead which concerns on 1st Embodiment, and an intermediate connection terminal. It is a front view of a superconducting current lead according to a comparative example. It is a graph which shows an example of the result of having calculated the temperature distribution of the superconducting current lead between the high temperature side electrode terminal and the low temperature side electrode terminal. It is sectional drawing of the high temperature side electrode terminal and superconducting wire in alignment with the line equivalent to the BB line of FIG. 1 in the superconducting electric current lead which concerns on the 1st modification of 1st Embodiment. It is a front view of the superconducting electric current lead which concerns on the 2nd modification of 1st Embodiment. It is an equivalent circuit diagram which shows the state of the electrical connection of the high temperature side electrode terminal of the superconducting electric current lead which concerns on the 2nd modification of 1st Embodiment, a 1st lead part, and an intermediate | middle connection terminal. It is a front view of the superconducting electric current lead which concerns on the 3rd modification of 1st Embodiment. It is a front view of the superconducting electric current lead which concerns on the 4th modification of 1st Embodiment. It is a front view of the superconducting electric current lead which concerns on the 5th modification of 1st Embodiment. It is a perspective view which expands and shows the area | region II enclosed with the dotted line in FIG. It is sectional drawing of the intermediate | middle connection terminal and superconducting wire in alignment with the CC line of FIG. It is a front view of the superconducting electric current lead which concerns on the 6th modification of 1st Embodiment. It is a front view of the superconducting electric current lead which concerns on the 7th modification of 1st Embodiment. It is a front view of the superconducting electric current lead which concerns on the 8th modification of 1st Embodiment. It is sectional drawing which shows the structure of the superconducting magnet apparatus which concerns on 2nd Embodiment.

Next, a mode for carrying out the present invention will be described with reference to the drawings.
(First embodiment)
First, the superconducting current lead according to the first embodiment will be described with reference to FIGS.

  FIG. 1 is a front view of a superconducting current lead 10 according to the present embodiment. FIG. 2 is an enlarged perspective view showing the vicinity of the intermediate connection terminal 15. FIG. 3 is a cross-sectional view of the intermediate connection terminal 15 and the superconducting wire along the line AA in FIG. In addition, illustration of a supporting member is abbreviate | omitted in FIG.

  As shown in FIG. 1, a superconducting current lead 10 according to the present embodiment includes a high temperature side electrode terminal 11, a low temperature side electrode terminal 12, a first lead portion 13, a second lead portion 14, an intermediate connection terminal 15, And a support member 16.

  The high temperature side electrode terminal 11 is an electrode terminal provided at one end of the superconducting current lead 10, and the low temperature side electrode terminal 12 is an electrode terminal provided at the other end of the superconducting current lead 10. The high temperature side electrode terminal 11 and the low temperature side electrode terminal 12 are made of a metal such as copper, which is a good electrical conductor.

  The first lead portion 13 is provided between the high-temperature side electrode terminal 11 and the low-temperature side electrode terminal 12, and from a first number of first superconducting wires W <b> 1 that are a plurality of pieces connected in parallel to each other. Become. In the example shown in FIG. 1, the first number is two.

  The second lead portion 14 is connected in series with the first lead portion 13 on the low temperature side electrode terminal 12 side of the first lead portion 13 between the high temperature side electrode terminal 11 and the low temperature side electrode terminal 12. The second superconducting wire W2 has a second number smaller than the first number. In the example shown in FIG. 1, the second number is one.

  That is, the superconducting current lead 10 according to the present embodiment is provided with the intermediate connection terminal 15 between the high temperature side electrode terminal 11 and the low temperature side electrode terminal 12, and between the intermediate connection terminal 15 and the low temperature side electrode terminal 12. The number of superconducting wires is reduced from the number of superconducting wires between the high temperature side electrode terminal 11 and the intermediate connection terminal 15.

  Moreover, in this Embodiment, both the 1st superconducting wire W1 and the 2nd superconducting wire W2 consist of a superconducting tape wire.

  The second superconducting wire W2 is composed of a superconducting wire continuous with the first superconducting wire W1. Thereby, since the connection resistance between the 1st lead part 13 and the 2nd lead part 14 becomes small, the superconducting current lead which can let a big current flow with a small number of superconducting wires is realizable. .

  In addition, let the 1st superconducting wire W1 comprised by the superconducting wire continuous with the 2nd superconducting wire W2 be the superconducting wire W11. Moreover, let the 1st superconducting wire W1 comprised by the superconducting wire which is not continuous with the 2nd superconducting wire W2 be the superconducting wire W12.

  As the superconducting wire constituting the first superconducting wire W1 and the second superconducting wire W2, for example, a high-temperature superconducting wire in which a multi-core wire such as Bi-2212 is coated with a metal such as silver as a base material, or Hastelloy, etc. Various superconducting wires such as a high-temperature superconducting wire obtained by depositing a thin film such as YBCO on the metal tape substrate can be used.

  The intermediate connection terminal 15 is provided between the first lead portion 13 and the second lead portion 14. The intermediate connection terminal 15 is connected to the low temperature side electrode terminal 12 side of the first lead portion 13 and to the high temperature side electrode terminal 11 side of the second lead portion 14.

  The intermediate connection terminal 15 is made of a metal such as copper, which is a good electrical conductor. 2 and 3, the intermediate connection terminal 15 has a plurality of grooves 17 extending from the high temperature side electrode terminal 11 side toward the low temperature side electrode terminal 12 side. The first superconducting wire W1 and the second superconducting wire W2 are embedded in the groove portion 17 by solder bonding.

  Specifically, the bottom surface and side surface of the groove portion 17 are thinly covered with solder by performing solder plating on the groove portion 17. Then, the superconducting wire is loaded into the groove 17 thinly coated with solder by solder plating, the melted solder 18 is filled into the groove 17 in a state where the superconducting wire is loaded, and the solder 18 is solidified, thereby superconducting. Solder the wire. By such a method, the superconducting wire can be embedded in the groove portion 17.

  Thus, by embedding the first superconducting wire W1 and the second superconducting wire W2 in the groove portion 17 of the intermediate connection terminal 15 made of a metal such as copper by soldering, the first superconducting wire W1 and Each wire of the second superconducting wire W2 can be reliably fixed to the intermediate connection terminal 15. In addition, each of the first superconducting wire W1 and the second superconducting wire W2 can be reliably electrically connected to the intermediate connection terminal 15. Thereby, the electrical resistance along the current path flowing between the first superconducting wire W1 and the second superconducting wire W2 through the solder and the copper portion of the intermediate connection terminal 15 can be reduced. The connection resistance between the first superconducting wire W1 and the second superconducting wire W2 can be reduced.

  Here, with reference to FIG. 4, the preferable range of the value of connection resistance is demonstrated. FIG. 4 is an equivalent circuit diagram showing a state of electrical connection between the first lead portion 13 and the intermediate connection terminal 15 of the superconducting current lead 10 according to the present embodiment.

The current flowing through the first superconducting wire W1 constituted (superconducting wire W11) by the superconducting wire continuous with the second superconducting wire W2 to I _1, is constituted by a superconducting wire which is not continuous with the second superconducting wire W2 the first superconducting wire W1 a current flowing through the (superconducting wire W12) and _{I 2} that. Then, the resistance in the first lead portion 13 of the superconducting wire W11 and _{R 1,} resistance in the first lead portion 13 of the superconducting wire W12, the connection resistance at the intermediate connection terminals 15, respectively and _R 2, _{R x.}

Here, since the resistance of the superconducting wire is negligibly small, R ₁ is the connection resistance between the high temperature side electrode terminal 11 and the superconducting wire W 11, and R ₂ is between the high temperature side electrode terminal 11 and the superconducting wire W 12. The connection resistance, _Rx, is the connection resistance from the superconducting wire W12 to the superconducting wire W11 via the intermediate connection terminal 15. Further, in the present application, the connection resistance is an electric resistance of a joining metal such as a solder used for connection between the superconducting wire and the metal (depending on a thickness of the joining metal such as a solder, a contact area between the metal and the superconducting wire). And the electrical resistance (depending on the shape of the metal) due to the bias of the current distribution inside the metal generated by connecting the superconducting wire to the metal.
Then, even when the current I ₁ flows through the superconducting wire W11, even if the current I ₂ flows through the superconducting wire W12, since the voltage applied to the first lead portion 13 are equal, equation (1)

が成り立つ。そして、式（１）を変形すると、電流Ｉ_１と電流Ｉ_２とは、式（２）

Holds. Then, when formula (1) is transformed, current I ₁ and current I ₂ are expressed by formula (2)

に示す関係で示される。

It is shown in the relationship shown in

Here, in order for the current I ₁ and the current I ₂ to be substantially equal, the expression (3)

に示す関係が満たされることが好ましい。

It is preferable that the relationship shown in is satisfied.

As shown in FIG. 2, the length of the intermediate connection terminal 15, that is, the length of the groove portion 17 is L1. Further, as shown in FIG. 3, the distance between the groove portions 17 is D1, the thickness of the intermediate connection terminal 15 below the groove portion 17 is T1, and the depth of the groove portion 17 is T2. Also, the thickness of the solder 18 in the direction parallel to the tape surface of the superconducting tape wire is D2, and the thickness of the solder 18 in the direction perpendicular to the tape surface is T3. The width of the superconducting tape wire is WD. As an example,
Electrical resistivity ρ _{Cu of copper} : 2.6 × 10 ⁻¹⁰ Ωm
Electrical resistivity ρ _S of solder 18: 1.0 × 10 ⁻⁹ Ωm
Solder 18 thickness D2 in the direction parallel to the tape surface D2: 0.05 mm
Thickness T3 of solder 18 in the direction perpendicular to the tape surface: 0.1 mm
Tape wire width WD: 4.3 mm
Groove 17 depth T2: 0.5 mm
Consider the case. And
Groove 17 length L1: 10 mm
Distance D1 between the groove portions 17: 2 mm
The thickness T1 of the intermediate connection terminal 15 below the groove portion 17 is 8 mm.
And When the connection resistance R _x is numerically calculated under such conditions, it is about 0.03 μΩ.

  Also, in order to ensure solder bonding, assuming that the thickness of the superconducting tape wire is WT, the depth T2 of the groove 17 may be larger than the total WT + T3 of the thickness WT and the thickness T3 of the solder 18. preferable.

  The support member 16 integrally supports the high temperature side electrode terminal 11, the low temperature side electrode terminal 12, and the intermediate connection terminal 15. That is, each of the high temperature side electrode terminal 11, the low temperature side electrode terminal 12, and the intermediate connection terminal 15 is fixed to the support member 16 provided integrally by, for example, screwing. By supporting the high temperature side electrode terminal 11, the low temperature side electrode terminal 12, and the intermediate connection terminal 15 by the support member 16, it is possible to prevent a decrease in the critical current value due to stress applied to the superconducting wire and distortion.

  In order to prevent heat from entering the low temperature side electrode terminal 12 through the support member 16, the support member 16 is preferably made of a material having a low thermal conductivity. As such a material having low thermal conductivity, for example, FRP (Fiber Reinforced Plastics), AlN, polyimide, or the like can be used.

  Further, in order to prevent a current from flowing from the high temperature side electrode terminal 11 to the low temperature side electrode terminal 12 through the support member 16, the support member 16 is electrically insulated from the high temperature side electrode terminal 11 and the low temperature side electrode terminal 12. It is preferable to support the electrode terminal 12. When a material having low thermal conductivity but not high electrical insulation is used as the support member 16, each of the high-temperature side electrode terminal 11, the low-temperature side electrode terminal 12, and the intermediate connection terminal 15 is electrically connected, for example. It can be fixed to the support member 16 using a nylon bolt or the like having a typical insulating property.

  Moreover, it is preferable that the difference in thermal expansion coefficient between the support member 16 and the superconducting wire is within ± 0.14%. When the difference in thermal expansion coefficient between the support member 16 and the superconducting wire exceeds ± 0.14%, the difference between the shrinkage of the support member 16 and the superconducting wire when the superconducting current lead 10 is cooled to the operating temperature. This is because the critical current value may be lowered due to the large strain applied in the direction from the high temperature side to the low temperature side of the superconducting wire. Therefore, when the difference in thermal expansion coefficient between the support member 16 and the superconducting wire is within ± 0.14%, it is possible to prevent a reduction in the critical current value of the superconducting current lead 10 due to the application of strain.

  Next, referring to FIG. 5, the superconducting current lead 10 according to the present embodiment invades into the low temperature side electrode terminal 12 without reducing the transport current as compared with the superconducting current lead 110 according to the comparative example. Will be described. FIG. 5 is a front view of the superconducting current lead 110 according to the comparative example.

  As shown in FIG. 5, the superconducting current lead 110 according to the comparative example includes a high temperature side electrode terminal 11, a low temperature side electrode terminal 12, and a support member 16. The high temperature side electrode terminal 11, the low temperature side electrode terminal 12, and the support member 16 are the same as those of the superconducting current lead 10 according to the first embodiment. On the other hand, the superconducting current lead 110 according to the comparative example does not have an intermediate connection terminal, and a single lead portion is provided between the high temperature side electrode terminal 11 and the low temperature side electrode terminal 12, and the lead portion. Is composed of a plurality of first superconducting wires W1. Similar to the superconducting current lead 10 according to the present embodiment, the first number is two.

  The critical current value of the superconducting wire decreases significantly with increasing temperature. Therefore, the superconducting wire connecting the high temperature side electrode terminal 11 and the low temperature side electrode terminal 12 has a maximum current that can be transported depending on the critical current value in the portion connected to the high temperature side electrode terminal 11 where the critical current value is the lowest. Limited.

  As shown in FIGS. 1 and 5, the number of superconducting wires connected to the high temperature side electrode terminal 11 is equal in both the superconducting current lead 10 according to the present embodiment and the superconducting current lead 110 according to the comparative example. Therefore, the maximum current that can be transported is also equal.

  On the other hand, the amount of heat entering the low temperature side electrode terminal 12 is proportional to the total cross-sectional area of the superconducting wire, that is, the number of superconducting wires. As shown in FIG. 1, the superconducting current lead 10 according to the present embodiment is such that the number of superconducting wires (one) between the intermediate connection terminal 15 and the low temperature side electrode terminal 12 is the same as that of the high temperature side electrode terminal 11. The number is less than the number of superconducting wires between the connection terminals 15 (two). Therefore, as shown in FIGS. 1 and 5, the number (1) of superconducting wires connected to the low temperature side electrode terminal 12 in the superconducting current lead 10 according to the present embodiment is the superconducting current lead 110 according to the comparative example. The number of superconducting wires connected to the low temperature side electrode terminal 12 is less than two (two). Therefore, the amount of heat entering the low-temperature side electrode terminal 12 in the superconducting current lead 10 according to the present embodiment is smaller than the amount of heat entering the low-temperature side electrode terminal 12 in the superconducting current lead 110 according to the comparative example.

  Next, referring to FIG. 6, a specific example of the amount that the superconducting current lead 10 according to the present embodiment can reduce the amount of heat entering the low temperature side electrode terminal 12 as compared with the superconducting current lead 110 according to the comparative example. explain. FIG. 6 is a graph showing an example of the result of calculating the temperature distribution of the superconducting current lead between the high temperature side electrode terminal 11 and the low temperature side electrode terminal 12.

  FIG. 6 shows the superconducting current lead 10 according to the present embodiment and the superconducting current lead 110 according to the comparative example, assuming that the temperature at the high temperature side electrode terminal 11 is 50K and the temperature at the low temperature side electrode terminal 12 is 4K. The temperature distribution between the high temperature side electrode terminal 11 and the low temperature side electrode terminal 12 is shown. The horizontal axis in FIG. 6 indicates the distance from the high temperature side electrode terminal 11 at each position, normalized with the distance from the high temperature side electrode terminal 11 to the low temperature side electrode terminal 12 as 1. The vertical axis in FIG. 6 indicates the temperature at each position. A solid line indicates a temperature distribution in the superconducting current lead 10 according to the present embodiment. The dotted line shows the temperature distribution in the superconducting current lead 110 according to the comparative example.

  In the superconducting current lead 110 according to the comparative example, the temperature uniformly decreases from the high temperature side electrode terminal 11 side (hereinafter referred to as “high temperature side”) toward the low temperature side electrode terminal 12 side (hereinafter referred to as “low temperature side”). To do. Also, the temperature changes with a slope that is inversely proportional to the thermal conductivity corresponding to the superconducting wire, but the thermal conductivity also decreases as the temperature decreases, so the slope becomes larger at the lower temperature side, and the convex curve shape is upward Indicates.

  On the other hand, in superconducting current lead 10 according to the present embodiment, in the region where intermediate connection terminal 15 is provided, heat is transferred by copper having a high thermal conductivity instead of the superconducting wire, so that the temperature becomes substantially constant. Accordingly, the temperature uniformly decreases from the high temperature side to the intermediate connection terminal 15, the temperature becomes substantially constant in the region where the intermediate connection terminal 15 is provided, and the temperature is again uniform from the intermediate connection terminal 15 to the low temperature side. descend.

  The intrusion heat quantity Q entering the low temperature side electrode terminal 12 is connected to the temperature gradient near the distance from the high temperature side electrode terminal 11, the thermal conductivity of the superconducting wire at that temperature, and the low temperature side electrode terminal 12. It can be determined based on the product of the number of superconducting wires made. The length of the intermediate connection terminal was set to about 8.3% of the length of the superconducting wire constituting the current lead, and the intrusion heat quantity Q was obtained from FIG. Then, Q = 0.269 W / m in the superconducting current lead 110 (dotted line) according to the comparative example, and Q = 0.148 W / m in the superconducting current lead 10 (solid line) according to the present embodiment. Therefore, according to the present embodiment, the number of superconducting wires between the intermediate connection terminal 15 and the low temperature side electrode terminal 12 is less than the number of superconducting wires between the high temperature side electrode terminal 11 and the intermediate connection terminal 15. Compared with the comparative example in which the number of superconducting wires does not change from the high temperature side electrode terminal 11 toward the low temperature side electrode terminal 12, for example, the intrusion heat quantity Q can be reduced by 45%.

  By changing the distance from the high-temperature side electrode terminal 11 of the intermediate connection terminal 15 when various conditions such as the number of superconducting wires, the material is changed, the magnitude of the magnetic field applied to the superconducting wire, and the like are changed. It is also possible to design so that the amount of intrusion heat becomes smaller.

  In the present embodiment, the example in which the superconducting current lead 10 has the intermediate connection terminal 15 between the first lead portion 13 and the second lead portion 14 has been described. However, it is sufficient that the first lead portion 13 and the second lead portion 14 are electrically connected, and there is no need for an intermediate connection terminal. When there is no intermediate connection terminal, electrical connection can be established by directly soldering each superconducting tape wire between the first lead portion 13 and the second lead portion 14.

Moreover, in this Embodiment, the example which is a superconducting tape wire which has a cross-sectional rectangular shape was demonstrated as a superconducting wire. However, the superconducting wire is not limited to one having a rectangular cross section, and may have a circular cross section or a polygonal cross section.
(First modification of the first embodiment)
Next, a superconducting current lead 10a according to a first modification of the first embodiment will be described with reference to FIG. FIG. 7 is a cross-sectional view of the high-temperature side electrode terminal 11a and the superconducting wire along the line corresponding to the line BB in FIG. 1 in the superconducting current lead 10a according to this modification. Note that the front view of the superconducting current lead 10a according to this modification is the same as the front view of the superconducting lead 10 according to the first embodiment shown in FIG.

  As shown in FIG. 7, the superconducting wire is embedded in the groove 17a formed in the high temperature side electrode terminal 11a by soldering using a solder 18a.

  Similarly to the first embodiment, the first superconducting wire W1 constituted by a superconducting wire continuous with the second superconducting wire W2 is defined as a superconducting wire W11. Moreover, let the 1st superconducting wire W1 comprised by the superconducting wire which is not continuous with the 2nd superconducting wire W2 be the superconducting wire W12. Then, in the superconducting current lead 10a according to this modification, as shown in FIG. 7, compared to the thickness TH1 in the high temperature side electrode terminal 11a in which the superconducting wire W11 is embedded, the high temperature side in which the superconducting wire W12 is embedded. The electrode terminal 11a has a large thickness TH2.

  That is, the high temperature side electrode terminal 11a has the convex part 11a-1 for increasing thickness in the surface opposite to the surface where the superconducting wire W12 is embedded. The convex portion 11a-1 corresponds to the resistance adjusting portion in the present invention.

In the equivalent circuit diagram shown in FIG. 4, when the connection resistance R _{x at} the intermediate connection terminal 15 is not sufficiently small as compared with the resistances R ₁ and R ₂ , the current I ₁ is obtained from the current I _{2 according} to the equation (2). Also grows. That is, in FIG. 4, the current I ₁ flowing through the superconducting wire W11 is larger than the current flowing through the superconducting wire W12. That is, the current I flowing between the high temperature side electrode terminal 11a and the low temperature side electrode terminal 12 is not evenly distributed to each superconducting wire, but is drifted. As a result, though the current I ₂ flowing through the superconducting wire W12 is not greater than the critical current value, only the current I ₁ flowing through the superconducting wire W11 is may exceed the critical current value, effective critical current value of each superconducting wire It cannot be used for.
Further, it is considered that the connection resistance between the superconducting wire and the high temperature side electrode terminal 11a is proportional to the -0.5th power of the thicknesses TH1 and TH2 of the high temperature side electrode terminal 11a. Then, as described above, since TH2 is thicker than thickness TH1, the connection resistance between superconducting wire W11 and high temperature side electrode terminal 11a is larger than the connection resistance between superconducting wire W12 and high temperature side electrode terminal 11a. become _large, the _R 1> R _2. Thereby, the current I ₁ and the current I ₂ can be made substantially equal in the expression (2).

That is, by providing the convex portion 11a-1, the connection resistance between the superconducting wire W11 and the high temperature side electrode terminal 11a is larger than the connection resistance between the superconducting wire W12 and the high temperature side electrode terminal 11a. Adjusted. As a result, the currents flowing through the first superconducting wires W11 and W12 can be made substantially equal, and the current I flowing between the high temperature side electrode terminal 11a and the low temperature side electrode terminal 12 is caused to drift to some superconducting wires. Instead, it can be distributed uniformly in each superconducting wire.
(Second modification of the first embodiment)
Next, a superconducting current lead 10b according to a second modification of the first embodiment will be described with reference to FIGS. FIG. 8 is a front view of a superconducting current lead 10b according to this modification. The portions other than the high temperature side electrode terminal 11b of the superconducting current lead 10b according to this modification are the same as those of the superconducting current lead 10 according to the first embodiment described with reference to FIG. 1, and FIG. The same reference numerals are given, and the description thereof is omitted (the same applies to the following modifications and embodiments). FIG. 9 is an equivalent circuit diagram showing a state of electrical connection of the high-temperature side electrode terminal 11b, the first lead portion 13, and the intermediate connection terminal 15 of the superconducting current lead 10b according to this modification.

  As shown in FIG. 8, the superconducting current lead 10b according to the present modification is divided into two parts by forming a slit S on the first lead part 13 side of the high temperature side electrode terminal 11b. Similarly to the first embodiment, the first superconducting wire W1 constituted by a superconducting wire continuous with the second superconducting wire W2 is defined as a superconducting wire W11. Moreover, let the 1st superconducting wire W1 comprised by the superconducting wire which is not continuous with the 2nd superconducting wire W2 be the superconducting wire W12. Then, the high temperature side electrode terminal 11b includes a first electrode terminal 11b-1 to which the superconducting wire W11 is connected, and a second electrode terminal 11b-2 in the high temperature side electrode terminal 11b to which the superconducting wire W12 is connected. It is divided into The slit S is formed so as to be substantially parallel to the superconducting wire, and is formed further to the high temperature side by a distance LH0 than the end of the connected superconducting wire.

The definitions of currents I ₁ and I ₂ and resistors R ₁ , R ₂ , and R _x are the same as those in the first embodiment. Also, let R _Cu be the resistance due to the high temperature electrode terminal 11b between the end of the connected superconducting wire and the upper end of the slit S. Then, the electrical connection state of the high temperature side electrode terminal 11b, the first lead portion 13, and the intermediate connection terminal 15 of the superconducting current lead 10b according to this modification is shown in FIG. The relationship between the currents I ₁ and I ₂ is expressed by the following formula (4) by the same derivation method as formula (2).

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When the distance LH0 is sufficiently long so that the resistance R _Cu is sufficiently larger than the resistance R _x , the current I ₁ and the current I ₂ can be made substantially equal in the equation (4). Thereby, the currents flowing through the first superconducting wires W11 and W12 can be made substantially equal, and the current I flowing between the high temperature side electrode terminal 11b and the low temperature side electrode terminal 12 is caused to drift to some of the superconducting wires. Instead, it can be distributed uniformly in each superconducting wire.
(Third modification of the first embodiment)
Next, a superconducting current lead 10c according to a third modification of the first embodiment will be described with reference to FIG. FIG. 10 is a front view of a superconducting current lead 10c according to this modification.

  Similarly to the first embodiment, the first superconducting wire W1 constituted by a superconducting wire continuous with the second superconducting wire W2 is defined as a superconducting wire W11. Moreover, let the 1st superconducting wire W1 comprised by the superconducting wire which is not continuous with the 2nd superconducting wire W2 be the superconducting wire W12. Then, as shown in FIG. 10, the superconducting current lead 10c according to this modification has the superconducting wire W12 embedded as compared with the groove length LH1 in the high temperature side electrode terminal 11c in which the superconducting wire W11 is embedded. The length LH2 of the groove in the high temperature side electrode terminal 11c is long. Further, the portion 11c-1 extending to the high temperature side by the length LH2-LH1 from the end of the groove portion having the length LH1 in which the superconducting wire W11 is embedded corresponds to the resistance adjusting portion in the present invention.

That is, in the present modification, similarly to the first modification of the first embodiment, the current I ₁ and the current I ₂ are substantially equal by setting R ₁ > R ₂ in the equation (2). To do. Therefore, the current I flowing between the high temperature side electrode terminal 11c and the low temperature side electrode terminal 12 can be made to flow evenly distributed in each superconducting wire without being biased to some superconducting wires.

That is, by providing the portion 11c-1, the connection resistance between the superconducting wire W11 and the high temperature side electrode terminal 11c is larger than the connection resistance between the superconducting wire W12 and the high temperature side electrode terminal 11c. Adjusted. As a result, the currents flowing through the first superconducting wires W11 and W12 can be made substantially equal, and the current I flowing between the high temperature side electrode terminal 11c and the low temperature side electrode terminal 12 is caused to drift to some superconducting wires. Instead, it can be distributed uniformly in each superconducting wire.
(Fourth modification of the first embodiment)
Next, a superconducting current lead 10d according to a fourth modification of the first embodiment will be described with reference to FIG. FIG. 11 is a front view of a superconducting current lead 10d according to this modification.

  Similarly to the first embodiment, the first superconducting wire W1 constituted by a superconducting wire continuous with the second superconducting wire W2 is defined as a superconducting wire W11. Moreover, let the 1st superconducting wire W1 comprised by the superconducting wire which is not continuous with the 2nd superconducting wire W2 be the superconducting wire W12. Then, in the superconducting current lead 10d according to this modification, as shown in FIG. 11, the superconducting wire W11 is connected to the high temperature side electrode terminal 11d via the connection resistance portion 11d-1. Moreover, the connection resistance part 11d-1 is corresponded to the resistance adjustment part in this invention. As the connection resistance portion 11d-1, for example, a metal material made of solder, stainless steel, brass, or the like can be used.

That is, in the present modification as well, as in the first modification of the first embodiment, the current I ₁ and the current I ₂ are approximately equal by setting R ₁ > R ₂ in Equation (2). To do. Therefore, the current I flowing between the high temperature side electrode terminal 11d and the low temperature side electrode terminal 12 can be distributed evenly in each superconducting wire without being biased to some superconducting wires.

That is, by providing the connection resistance portion 11d-1, the connection resistance between the superconducting wire W11 and the high temperature side electrode terminal 11d is larger than the connection resistance between the superconducting wire W12 and the high temperature side electrode terminal 11d. Adjusted. Thereby, the currents flowing through the first superconducting wires W11 and W12 can be made substantially equal, and the current I flowing between the high temperature side electrode terminal 11d and the low temperature side electrode terminal 12 is caused to drift to some superconducting wires. Instead, it can be distributed uniformly in each superconducting wire.
(Fifth modification of the first embodiment)
Next, a superconducting current lead 10e according to a fifth modification of the first embodiment will be described with reference to FIGS. FIG. 12 is a front view of a superconducting current lead 10e according to this modification. FIG. 13 is an enlarged perspective view showing a region II surrounded by a dotted line in FIG. 14 is a cross-sectional view of the intermediate connection terminal 15e and the superconducting wire along the line CC in FIG.

  As shown in FIG. 12, the superconducting current lead 10e according to the present modification is provided in the first lead portion 13 and the second lead portion 14 so that the respective tape surfaces of the superconducting wire that is a superconducting tape wire face each other. It has been. The second superconducting wire W2 is composed of a superconducting wire continuous with the first superconducting wire W1, as in the first embodiment.

  An intermediate connection terminal 15e is provided between the first lead portion 13 and the second lead portion 14, and the low-temperature side electrode terminal 12 side of the first lead 13 portion is connected, and the second lead The high temperature side electrode terminal 11 side of the part 14 is connected in the same manner as in the first embodiment. Also, the intermediate connection terminal 15e is made of a metal such as copper, which is a good electrical conductor, as in the first embodiment.

  On the other hand, as shown in FIGS. 13 and 14, the intermediate connection terminal 15 e extends from the high temperature side electrode terminal 11 side to the low temperature side electrode terminal 12 side on one surface and the surface opposite to the one surface. A plurality of grooves 17 are provided, and a cross section perpendicular to the direction from the high temperature side electrode terminal 11 side to the low temperature side electrode terminal 12 side has an H-shape. The first superconducting wire W1 and the second superconducting wire W2 are embedded in the groove portion 17 by solder bonding. As a result, the resistance along the current path flowing between the first superconducting wire W1 and the second superconducting wire W2 via the copper portion of the solder 18 and the intermediate connection terminal 15e can be reduced. The connection resistance between the first superconducting wire W1 and the second superconducting wire W2 can be reduced.

As shown in FIG. 13, the length of the intermediate connection terminal 15e, that is, the length of the groove portion 17 is L2. Further, as shown in FIG. 14, the distance between the bottom surfaces of the groove portions 17 formed on one surface and the opposite surface is T4, and L2 = 10 mm and T4 = 5 mm. Further, the electrical resistivity ρ _{Cu of copper} , the electrical resistivity ρ _S of the solder 18, the thickness D2 of the solder 18 in the direction parallel to the tape surface, the thickness T3 of the solder 18 in the direction perpendicular to the tape surface, and the tape wire The width WD and the depth T2 of the groove portion 17 are the same as those in the first embodiment. When the connection resistance _Rx between the first superconducting wire W1 and the second superconducting wire W2 is numerically calculated under such conditions, it is about 0.023 μΩ.

  Also, in order to ensure solder bonding, assuming that the thickness of the superconducting tape wire is WT, the depth T2 of the groove 17 may be larger than the total WT + T3 of the thickness WT and the thickness T3 of the solder 18. preferable.

  Also in this modification, the number of superconducting wires between the intermediate connection terminal 15e and the low temperature side electrode terminal 12 is reduced by reducing the number of superconducting wires between the high temperature side electrode terminal 11 and the intermediate connection terminal 15e. The amount of heat Q entering the side electrode terminals 12 can be reduced.

Also in this modification, the superconducting wire is connected to the high temperature side electrode terminal 11 by the connection method in the superconducting current lead according to any one of the first to fourth modifications of the first embodiment. Can do. Thereby, the currents flowing through the first superconducting wires W11 and W12 can be made substantially equal, and the current I flowing between the high temperature side electrode terminal 11 and the low temperature side electrode terminal 12 is caused to drift to some superconducting wires. Instead, it can be distributed uniformly in each superconducting wire.
(Sixth modification of the first embodiment)
Next, a superconducting current lead 10f according to a sixth modification of the first embodiment will be described with reference to FIG. FIG. 15 is a front view of a superconducting current lead 10f according to this modification.

  In the superconducting current lead 10f according to the present modification, the second superconducting wire W2 is not composed of a superconducting wire continuous with the first superconducting wire W1.

  As shown in FIG. 15, in the superconducting current lead 10 f according to this modification, all of the second superconducting wire W <b> 2 are connected to the first superconducting wire W <b> 1 through the intermediate connection terminal 15. Except that the second superconducting wire W2 is not composed of a superconducting wire that is continuous with the first superconducting wire W1, the superconducting current lead 10f according to the present modification is the first described with reference to FIG. The configuration is the same as that of the superconducting current lead 10 according to the embodiment.

In the superconducting current lead 10f according to this modification, since none of the second superconducting wire W2 is continuous with the first superconducting wire W1, the high-temperature side electrode terminal 11 in each superconducting wire of the first superconducting wire W1 The connection resistance between the intermediate connection terminals 15 can be made equal. Thereby, a superconducting wire or a superconducting tape wire with a low manufacturing cost can be used, the amount of heat entering the low temperature side can be reduced, and the heat flows between the high temperature side electrode terminal 11 and the low temperature side electrode terminal 12. The current I can be made to flow evenly distributed to each superconducting wire without being biased to some superconducting wires.
(Seventh Modification of First Embodiment)
Next, a superconducting current lead 10g according to a seventh modification of the first embodiment will be described with reference to FIG. FIG. 16 is a front view of a superconducting current lead 10g according to this modification.

  In the superconducting current lead 10g according to this modification, the first lead portion 13 is composed of three first superconducting wires W1, and the second lead portion 14 is composed of two second superconducting wires W2. The first lead portion 13 is composed of three first superconducting wires W1 connected in parallel to each other. The second lead portion 14 is composed of two second superconducting wires W2 connected in parallel to each other.

  The number of second superconducting wires W2 (second number) in the second lead portion 14 should be less than the number (first number) of first superconducting wires W1 in the first lead portion 13, As shown in this modification, both the second number and the first number can be any number.

  Further, the difference between the second number and the first number may not be one as shown in the present modification, but may be two or more.

  The superconducting current lead 10g according to this modification is also provided with an intermediate connection terminal 15 between the high temperature side electrode terminal 11 and the low temperature side electrode terminal 12, and the superconducting wire rod between the intermediate connection terminal 15 and the low temperature side electrode terminal 12 is provided. The number is reduced from the number of superconducting wires between the high temperature side electrode terminal 11 and the intermediate connection terminal 15. Accordingly, it is possible to use a superconducting wire or a superconducting tape wire with a low manufacturing cost, and to reduce the amount of intrusion heat entering the low temperature side.

Also in this modification, the superconducting wire is connected to the high temperature side electrode terminal 11 by the connection method in the superconducting current lead according to any one of the first to fourth modifications of the first embodiment. Can do. Thereby, the currents flowing through the first superconducting wires W11 and W12 can be made substantially equal, and the current I flowing between the high temperature side electrode terminal 11 and the low temperature side electrode terminal 12 is caused to drift to some superconducting wires. Instead, it can be distributed uniformly in each superconducting wire.
(Eighth modification of the first embodiment)
Next, with reference to FIG. 17, a superconducting current lead 10h according to an eighth modification of the first embodiment will be described. FIG. 17 is a front view of a superconducting current lead 10h according to this modification.

  The superconducting current lead 10h according to the present modification is provided between the second lead portion 14 and the low temperature side electrode terminal 12, and the number of second superconducting wires W2 in the second lead portion 14 (second The number of the third lead portions 14h made of the third superconducting wire W3 (the third number) is smaller than the number of the third lead portions 14h. Also, the superconducting current lead 10h is provided between the second lead portion 14 and the third lead portion 14h, and the low-temperature side electrode terminal 12 side of the second lead portion 14 is connected to the third lead portion 14h. The lead portion 14h has a second intermediate connection terminal 15h to which the high temperature side electrode terminal 11 side is connected.

  The shape, structure, material, and the like of the second intermediate connection terminal 15 h can be the same as those of the intermediate connection terminal 15 provided between the first lead portion 13 and the second lead portion 14.

  In addition, each lead part 13,14,14h connects between the high temperature side electrode terminal 11 and the low temperature side electrode terminal 12 in series via the intermediate connection terminals 15 and 15h, respectively. What is necessary is that the number of superconducting wires in 14 and 14h decreases sequentially from the high temperature side electrode terminal 11 side toward the low temperature side electrode terminal 12 side. Therefore, the number of lead portions connecting the high temperature side electrode terminal 11 and the low temperature side electrode terminal 12 in series can be set to an arbitrary number n (n = 1, 2, 3,...) The number of intermediate connection terminals for connecting each lead portion can be n-1.

  The superconducting current lead 10h according to this modification is provided with intermediate connection terminals 15 and 15h connected in series between the high temperature side electrode terminal 11 and the low temperature side electrode terminal 12, and each of the intermediate connection terminals has a high temperature side electrode terminal. The number of superconducting wires on the low temperature side electrode terminal 12 side is reduced as compared with the number of superconducting wires on the 11 side. Accordingly, it is possible to use a superconducting wire or a superconducting tape wire with a low manufacturing cost, and to reduce the amount of intrusion heat entering the low temperature side.

Also in this modification, the superconducting wire can be connected to the high temperature side electrode terminal by the connection method in the superconducting current lead according to any one of the first to fourth modifications of the first embodiment. it can. Thereby, the currents flowing through the first superconducting wires W11 and W12 can be made substantially equal, and the current I flowing between the high temperature side electrode terminal 11 and the low temperature side electrode terminal 12 is caused to drift to some superconducting wires. Instead, it can be distributed uniformly in each superconducting wire.
(Second Embodiment)
Next, the superconducting magnet device 20 according to the second embodiment will be described with reference to FIG. FIG. 18 is a cross-sectional view showing the configuration of the superconducting magnet device 20.

  The superconducting magnet device 20 according to the present embodiment is an application of the superconducting current lead 10 according to the first embodiment to a refrigerator-cooled superconducting magnet device. As the refrigerator, for example, a one-stage or two-stage Gifford-McMahon (GM) refrigerator can be used.

  The superconducting magnet device 20 includes a vacuum container 21, a GM refrigerator 22, a radiation shield member 23, a superconducting coil 24, a high temperature side cooling stage 25, a low temperature side cooling stage 26, a superconducting current lead 10, and a power source 27.

  The vacuum vessel 21 has, for example, a substantially cylindrical shape. A GM refrigerator 22 is fixed on the upper surface of the vacuum vessel 21.

  The GM refrigerator 22 has a multi-stage cooling cylinder structure including a first-stage cooling cylinder 22a and a second-stage cooling cylinder 22b. The first-stage cooling cylinder 22 a and the second-stage cooling cylinder 22 b are inserted into the vacuum vessel 21. The second-stage cooling cylinder 22 b is also inserted into the radiation shield member 23 provided in the vacuum vessel 21.

  The radiation shield member 23 is formed of a high thermal conductivity member such as copper or aluminum and has, for example, a substantially cylindrical shape. A high temperature side cooling stage 25 is fixed to the top of the top plate of the radiation shield member 23, and a first stage cooling cylinder 22 a is connected to the high temperature side cooling stage 25. Therefore, the high temperature side cooling stage 25 is cooled by the first stage cooling cylinder 22a. A second stage cooling cylinder 22 b is provided below the top plate of the radiation shield member 23 so as to be connected to the high temperature side cooling stage 25. A low temperature side cooling stage 26 is connected to the lower end of the second stage cooling cylinder 22b. Therefore, the low temperature side cooling stage 26 is cooled by the second stage cooling cylinder 22b. The high temperature side cooling stage 25 and the low temperature side cooling stage 26 are formed of a high thermal conductivity member such as copper or aluminum.

  The superconducting coil 24 is provided inside the radiation shield member 23. The superconducting coil 24 is connected to the low temperature side cooling stage 26 via the Cu heat transfer plate 28, and is thereby cooled by the GM refrigerator 22 to be in a superconducting state. In the example shown in FIG. 18, the space surrounded by the superconducting coil 24 is included in the radiation shield member 23, but the vacuum vessel 21 and the radiation shield member 23 are provided with a concave portion having a cylindrical shape, The coil 24 may surround a space defined by the recess.

  The superconducting coil 24 is supplied with power from the power source 27 via the wiring 29 and the superconducting current lead 10. The wiring 29 passes through the insulator 30 provided in the vacuum vessel 21 and the radiation shield member 23, and is connected to a power source 27 provided outside the vacuum vessel 21 and a superconducting current lead at a high temperature portion 31 inside the radiation shield member 23. 10 high temperature side electrode terminals 11 are connected. The low temperature side electrode terminal 12 of the superconducting current lead 10 is connected to a coil electrode (not shown) of the superconducting coil 24 at the low temperature portion 32 inside the radiation shield member 23.

  That is, in the present embodiment, the superconducting current lead 10 has the high temperature side electrode terminal 11 connected to the high temperature portion 31 in the superconducting magnet device 20 and the low temperature side electrode terminal 12 connected to the low temperature portion in the superconducting magnet device 20. 32.

  In the present embodiment, superconducting current leads 10a to 10h according to any of the first to eighth modifications of the first embodiment may be used instead of superconducting current leads 10.

  The superconducting current lead 10 may be surrounded by a magnetic shield member (not shown) made of a high-temperature superconducting material such as Bi-2212 or YBCO.

  In the superconducting magnet device 20 according to the present embodiment, a superconducting wire or a superconducting tape wire with a low manufacturing cost can be used as the superconducting current lead 10, and the intrusion heat amount entering the superconducting coil can be reduced on the low temperature side. Can do. Therefore, it is possible to prevent the superconducting coil 24 from rising in temperature and lowering the critical current value, or from further rising in temperature and shifting to the normal conducting state. Thereby, the power consumption accompanying the driving | operation of GM refrigerator 22 can be reduced, and stability of the magnetic field which the superconducting magnet apparatus 20 generate | occur | produces can be improved.

Furthermore, in the superconducting magnet device 20 according to the present embodiment, the first superconducting tape wire W1 and the second superconducting tape wire W2 are formed of the tape surface of the first superconducting tape wire W1 and the second superconducting tape wire W2. The tape surface is preferably provided so as to be substantially parallel to the magnetic field H generated by the superconducting magnet device 20. As shown in FIG. 18, for example, the superconducting current lead 10 is arranged in the vicinity of the central axis CA of the superconducting coil 24 and substantially parallel to the central axis CA, so that it is substantially parallel to the magnetic field H generated by the superconducting magnet device 20. Can be.
Here, the superconducting characteristics of the oxide superconducting material are anisotropic, and the critical current is significantly lowered when a magnetic field is applied perpendicular to the tape surface. Therefore, by arranging the superconducting tape wire so that the tape surface is substantially parallel to the magnetic field generated by the superconducting magnet device 20, the critical current value of the superconducting current lead is reduced by the magnetic field generated by the superconducting magnet device 20. Can be prevented.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to such specific embodiments, and various modifications can be made within the scope of the gist of the present invention described in the claims. Can be modified or changed.

10, 10a to 10h, 110 Superconducting current lead 11, 11a to 11d High temperature side electrode terminal 12 Low temperature side electrode terminal 13 First lead portion 14 Second lead portion 14h Third lead portion 15, 15e Intermediate connection terminal 15h First 2 intermediate connection terminals 16 support members 17 and 17a groove portions 18 and 18a solder 20 superconducting magnet device 21 vacuum vessel 22 GM refrigerator 22a first stage cooling cylinder 22b second stage cooling cylinder 23 radiation shield member 24 superconducting coil 25 high temperature side cooling Stage 26 Low temperature side cooling stage 27 Power supply 28 Cu heat transfer plate 29 Wiring 30 Insulator 31 High temperature part 32 Low temperature part CA Central axis H Magnetic field W1 First superconducting wire W2 Second superconducting wire

Claims (8)

A high temperature side electrode terminal provided at one end;
A low temperature side electrode terminal provided at the other end;
A first lead portion made of a plurality of first superconducting wires provided in parallel between the high temperature side electrode terminal and the low temperature side electrode terminal;
The first lead portion and the low-temperature side electrode terminal are provided so as to be connected in series with the first lead portion, and the number of the first superconducting wire is less than the number of the first superconducting wires. A superconducting current lead having a second lead portion made of two superconducting wires.   2. The superconducting current lead according to claim 1, further comprising an intermediate connection terminal that connects the low temperature side electrode terminal side of the first lead portion and the high temperature side electrode terminal side of the second lead portion. The intermediate connection terminal has a plurality of grooves formed to extend from the high temperature side electrode terminal side toward the low temperature side electrode terminal side,
3. The superconducting current lead according to claim 2, wherein each of the first superconducting wire and the second superconducting wire is embedded in the groove by solder bonding.   The superconducting current lead according to any one of claims 1 to 3, wherein the second superconducting wire is composed of a superconducting wire that is continuous with the first superconducting wire. The high temperature side electrode terminal side of the first lead portion is connected to the high temperature side electrode terminal,
The high temperature side electrode terminal has a connection resistance between the first superconducting wire composed of a superconducting wire continuous with the second superconducting wire and the high temperature side electrode terminal, and is continuous with the second superconducting wire. 5. A resistance adjustment unit for adjusting the first superconducting wire composed of a superconducting wire other than the superconducting wire to be larger than a connection resistance between the high temperature side electrode terminal and the first superconducting wire. Superconducting current lead.   The superconducting current lead according to any one of claims 1 to 5, further comprising a support member that integrally supports the high temperature side electrode terminal and the low temperature side electrode terminal.   The difference in thermal expansion coefficient between the support member and the first superconducting wire and the difference in thermal expansion coefficient between the support member and the second superconducting wire are within ± 0.14%. 7. A superconducting current lead according to item 6. The superconducting wire is a superconducting tape wire,
The first superconducting wire is a first superconducting tape wire,
The second superconducting wire is a second superconducting tape wire,
The superconducting current lead is such that the high temperature side electrode terminal is connected to a high temperature part in the superconducting magnet device, and the low temperature side electrode terminal is connected to a low temperature part in the superconducting magnet device,
In the first superconducting tape wire and the second superconducting tape wire, the tape surface of the first superconducting tape wire and the tape surface of the second superconducting tape wire are substantially in the magnetic field generated by the superconducting magnet device. The superconducting current lead according to any one of claims 1 to 7, which is arranged so as to be parallel to each other.

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