JP3792132B2 - Electrode structure of oxide superconducting current lead - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrode structure of an oxide superconducting current lead connected to a superconducting coil of a refrigerator-cooled superconducting magnet.
[0002]
[Prior art]
Conventionally, a refrigerator cooled superconducting magnet as shown in FIG. 4 has been proposed.
[0003]
In a superconducting magnet 50 as shown in FIG. 4, a coil winding frame 52 is disposed in a vacuum vessel 51, and a so-called superconducting coil 53 is wound around the coil winding frame 52. An outer periphery cooling copper block 54 is attached to the outer peripheral surface of the coil winding frame 52, and the outer periphery cooling copper block 54 is attached to the cooling stage 55 together with the coil winding frame 52. The cooling stage 55 is supported by a refrigerant (for example, helium) passage pipe portion 56.
[0004]
Further, a pair of electrodes (hereinafter referred to as “low temperature side electrodes”) 57 and 57 are supported on the cooling stage 55 via insulators (not shown), and these low temperature side electrodes are not shown. 57 and 57 are connected to the coil 53, respectively. Another cooling stage 58 is supported on the lower side of the cooling stage 55 by the refrigerant passage pipe portion 56. The cooling stage 58 includes a pair of electrodes (hereinafter referred to as high temperature side electrodes) 59 and 59 is supported via an insulator (not shown). An oxide superconducting current lead bulk 60 is mounted between the corresponding low temperature side electrode 57 and high temperature side electrode 59, respectively. The low temperature side electrode 57, the high temperature side electrode 59, and the current lead bulk 60 are used. A superconducting current lead is formed.
[0005]
The superconducting coil 53 is covered with a heat shield plate 61 supported on the outer peripheral end of the cooling stage 58. A copper current lead 62 is connected to the high temperature side electrodes 59 and 59 (FIG. 5 shows only the copper current lead 62 connected to the high temperature side electrode 59). Has been drawn to. A so-called GM refrigerator 63 is attached to the lower side of the vacuum vessel 51, and the refrigerator 63 is connected to the refrigerant passage pipe portion 56.
[0006]
High-temperature and low-temperature side electrodes (copper caps) 57 and 59 as shown in FIGS. 5 and 6 have been used as electrodes for energizing such conventional refrigerator-cooled oxide superconducting current leads.
[0007]
5 is a partial side sectional view showing a conventional oxide superconducting current lead, FIG. 6 (a) is a plan sectional view showing a copper cap of the oxide superconducting lead of FIG. 5, and FIG. 6 (b) is FIG. 6 (a). Fig. 6C is a side view of the copper cap of Fig. 6B, and Fig. 6D is another side view of the copper cap of Fig. 6B.
[0008]
As shown in FIG. 5, copper caps 57 and 59 are attached to both ends of a hollow cylindrical oxide superconducting current lead bulk 60 and soldered and fixed as indicated by reference numeral 65. Here, since the copper caps 57 and 59 have the same shape, only the copper cap 57 will be described here.
[0009]
Referring to FIG. 6, the copper cap 57 includes a cylindrical outer cylinder portion 57b and an inner cylinder portion 57c that is press-fitted and attached to one end through the inside of the outer cylinder portion 57b. Further, a plate-like connecting portion 57d is provided axially outward from one end of the outer cylindrical portion 57b, and screw holes 57a and 57a for fixing are provided in the connecting portion.
[0010]
One end of the oxide superconducting current lead bulk 60 is sandwiched between the outer cylindrical portions 57b and 57c of the copper cap 57 and joined and fixed by soldering.
[0011]
When the copper caps 57 and 59 were energized at 1000 A in liquid nitrogen (77 K), the connection resistance was 0.2 μΩ or less, indicating a good value.
[0012]
[Problems to be solved by the invention]
However, when a current lead using the above-described copper cap electrode is incorporated in the device, external force due to heat shrinkage (about 5K at the lowest point) or vibration is directly applied to the current lead, and the connection resistance of the electrode portion increases. In some cases, current leads could be damaged.
[0013]
Therefore, in order to relieve the external force, as shown in FIG. 7, a flexible structure is adopted in which the tip 66a is attached to one side electrode of the oxide superconducting current lead bulk 60 by using a copper mesh 66 or the like. There was also.
[0014]
In this conventional knitted electrode, the external force could be reduced, but the copper mesh wire 66 must be soldered as indicated by reference numeral 65, so that time is required for soldering. Therefore, there was a case where the solder was not partially attached. For this reason, regarding the connection resistance in the electrode portion, individual variations are large, and the connection resistance is also larger than that of the Cu cap electrode. For example, some of them did not clear the reference value of connection resistance of 0.5 μΩ or less (when 1000 A was energized).
[0015]
Therefore, the technical problem of the present invention is to reduce the load applied to the current lead due to external force such as thermal contraction or vibration during cooling with respect to the electrode of the oxide superconducting current lead used in the superconducting magnet cooled by the refrigerator, It is an object of the present invention to provide an electrode structure of an oxide superconducting current lead capable of preventing breakage of current leads and preventing characteristic deterioration.
[0016]
[Means for Solving the Problems]
According to the present invention, in the electrode structure used for the refrigerator-cooled superconducting magnet and provided at both ends of the oxide superconducting current lead connected to the superconducting coil, supporting and electrically connecting the oxide superconducting lead, A pair of caps attached to both ends of the oxide superconducting current lead; a pair of high-temperature side electrode connection portions connected to one end of each of the pair of caps; and a low-temperature side electrode connection portion; The connecting portion is made of a plate material having a flexible S-shaped portion whose one end joined to the cap is bent twice into a U shape, and the connecting portion of the low temperature side electrode is one end joined to the cap. side is a plate member having a portion of the flexible U-shaped terminal portions connected to the connecting portion of the low-temperature side electrode has an L-shape, of the high temperature side electrode The connecting portion is formed with a terminal portion extending from the S-shaped portion, and at least one notch is formed in at least one of the bent portion of the S-shaped portion and the bent portion of the U-shaped portion. An electrode of an oxide superconducting current lead , wherein the S-shaped portion and the U-shaped portion are provided at positions rotated by 90 degrees around the central axis. A structure is obtained.
[0018]
According to the present invention, in the electrode structure of the oxide superconducting current lead, the U-shaped portions at both ends are provided so as to be displaced from each other around the central axis of the oxide superconducting current lead. Thus, an electrode structure of an oxide superconducting current lead can be obtained.
[0020]
According to the present invention, in the electrode structure of the oxide superconducting current lead, the cap has at least two slits made of cuts provided in the axial direction, and the oxide superconducting current is characterized in that A lead electrode structure is obtained.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0022]
1A is a front sectional view showing an oxide superconducting current lead portion according to an embodiment of the present invention, and FIG. 1B is a partial side view of a high temperature side electrode of the oxide supercurrent lead portion of FIG. FIG. 1C is a partial side view of the low temperature side electrode of the oxide supercurrent lead portion of FIG.
[0023]
As shown in FIG. 1 (a), an oxide superconducting current lead includes a hollow cylindrical oxide superconducting current lead bulk 20, a high temperature side electrode provided at one end thereof, and a low temperature side electrode provided at the other end. And. The oxide superconducting lead bulk 20 has a hollow cylindrical shape, similar to that described in the prior art. Each electrode is formed from fully annealed copper.
[0024]
The high temperature side electrode has a cap shape including a cap portion 1 made of copper and a connection portion 2 having one end joined to one end thereof by soldering or the like. The cap portion 1 has a double cylindrical structure, similar to that described in the prior art. However, the embodiment according to the present invention is different from that according to the prior art in that the slit 3a is formed by cutting from the opening side provided in the axial direction. Moreover, the connection part 2 has the shape which bent the end of the elongate copper plate twice in the U shape, ie, the S shape. As will be described later in detail, the bent portion (R portion) 2a on the cap portion / side of the connecting portion 2 is provided with a cut in the length direction, and this portion is provided with flexibility. The other end side continuous with the bent portions 2a and 2b is a straight terminal portion 2c in which a long hole 2d is formed.
[0025]
Moreover, the low temperature side electrode is provided with the cap part 3 which consists of copper, and the connection part 4 by which the one end was connected to the one end by soldering etc. The cap part 3 has a double cylindrical shape like the cap part 1, and is provided with a slit 3a from the opening side. The other end side of the connecting portion 4 opposite to the side joined to the cap portion 1 is soldered to the support base 5.
[0026]
Further, the support base 5 is provided with an L-shaped elongated copper plate 6 having circular holes 6a, 6a as terminal portions.
[0027]
The connecting portions 2 and 4 are provided so as to be shifted from each other by 90 degrees around the axis via the oxide superconducting current lead block 20.
[0028]
2A is a partial plan view showing the bent portion 2a of the connecting portion 2, FIG. 2B is a partial front view showing the bent portion 2a of the connecting portion 2, and FIG. 2C is a bent portion of the connecting portion 2. It is a perspective view which shows 2a.
[0029]
Referring to FIG. 2, the connecting portion 2 is provided with slits 21 and 21 each having two cuts along the bent portion so as to pass through the bent portion 2a. Thereby, the bending part 2a becomes flexible.
[0030]
FIG. 3A is a cross sectional view showing the low temperature side electrode, and FIG. 3B is a vertical cross sectional view of the low temperature side electrode of FIG.
[0031]
3A and 3B, the cap portion 3 has a double cylindrical shape, and the outer cylindrical portion is provided with two slits 3a and 3a in the axial direction. The connecting portion 4 that supports the cap is U-shaped, and a slit 41 formed by cutting in the length direction is provided in the same shape as the slit 21 in FIG. 2 so as to pass through the bent portion (R portion). ing.
[0032]
In order to manufacture such an oxide superconducting current lead portion, as shown in FIG. 1, the openings of the cap portions 1 and 3 of the high temperature side electrode and the low temperature side electrode are respectively inserted into both ends of the oxide superconducting lead bulk 20. That's fine.
[0033]
In addition, the cap portions 1 and 3 and the connection portions 2 and 4 may be joined after the cap portions 1 and 3 are provided on the oxide superconducting lead bulk 20, but the U-shaped positions of the respective connection portions are It must be configured to be 90 degrees off axis.
[0034]
As described above, in the electrode structure according to the embodiment of the present invention, both end electrodes of the oxide superconducting current lead have a structure in which a U-shaped plate is incorporated, and the U-shape is 90 degrees between the high temperature side and the low temperature side. Have an angle. The U-shaped portion is provided with two slits 21, 21 and 41, 41 for further flexibility.
[0035]
Furthermore, since the cap portions 1 and 3 are provided with the slits 3a, stress applied in the circumferential direction of the electrode due to thermal contraction can be relieved.
[0036]
Next, the effect of the current lead using the electrode structure according to the embodiment of the present invention was examined.
[0037]
The connection resistance at that time was stably 0.2 μΩ or less (at a liquid nitrogen temperature of 77 K when 1000 A was energized), and there was almost no individual variation. (Clear specification 0.5 μΩ or less) In addition, the electrode structure of the present invention was able to absorb a displacement of about 3 mm in the longitudinal and lateral directions of the current lead.
[0038]
Further, since the actual heat shrinkage is 1 mm or less in the maximum longitudinal direction, it is sufficiently acceptable.
[0039]
Further, in the electrode structure according to the embodiment of the present invention, the displacement is about 3 mm with an external force of several hundred grams, and the thermal contraction force or other external force actually applied to the current lead is 2 kg at most. Can be absorbed. As a result, it has been found that almost no external force is applied to the current lead.
[0040]
In addition, the current lead using the electrode structure according to the embodiment of the present invention has been incorporated in the refrigerator-cooled superconducting magnet and has been operating for one year or more, but has been operating without any problem.
[0041]
In the electrode structure according to the embodiment of the present invention described above, in addition to the current lead of the refrigerator-cooled superconducting magnet (not limited to the superconducting magnet), an electrode for energizing current to a refrigerator or a low-temperature device using liquid helium As promising.
[0042]
In addition, the electrode structure according to the embodiment of the present invention can be applied to oxide superconductivity in general (Bi-based superconductor, Y-based superconductor, oxide Ag sheath wire, etc.).
[0043]
【The invention's effect】
As described above, according to the present invention, with respect to the electrode of the oxide superconducting current lead used in the refrigerator-conducting superconducting magnet, the load on the current lead due to external force such as thermal contraction or vibration during cooling is reduced. In addition, it is possible to provide an electrode structure of an oxide superconducting current lead that can prevent a current lead from being damaged and prevent deterioration of characteristics.
[Brief description of the drawings]
FIG. 1A is a front sectional view showing an oxide superconducting current lead portion according to an embodiment of the present invention.
(B) is the partial side view of the high temperature side electrode of the oxide supercurrent lead | read | reed part of (a).
(C) is the partial side view of the low temperature side electrode of the oxide supercurrent lead | read | reed part of (a).
2A is a partial plan view showing a bent portion 2a of a connecting portion 2. FIG.
FIG. 4B is a partial front view showing a bent portion 2a of the connection portion 2;
(C) is a perspective view showing a bent portion 2a of the connecting portion 2. FIG.
FIG. 3A is a plan sectional view showing a low temperature side electrode.
(B) is a longitudinal cross-sectional view of the low temperature side electrode of (a).
FIG. 4 is a view showing a refrigerator-cooled superconducting magnet according to the prior art.
FIG. 5 is a partial side sectional view showing a conventional oxide superconducting current lead.
6A is a plan sectional view showing a copper cap of the oxide superconducting lead of FIG.
(B) is front sectional drawing of the copper cap of (a).
(C) is one side view of the copper cap of (b).
(D) is another side view of the copper cap of (b).
7 is a front view showing another example of an electrode of a conventional oxide superconducting current lead bulk 60. FIG.
[Explanation of symbols]
1 Cap (high temperature side electrode)
2 Connection part 2a, 2b Bending part (R part)
2c Terminal part 2d Long hole 3 Cap part (low temperature side electrode)
3a Slit 4 Connection 5 Support base 6 Terminal 6a Hole 20 Oxide superconducting current lead bulk 21, 41 Slit 50 Superconducting magnet 51 Vacuum vessel 52 Coil frame 53 Superconducting coil 54 Copper block 55 for cooling outer periphery 55 Cooling stage 56 Passage Tube portion 57 Low temperature side electrode 57a Screw hole 57b Outer cylindrical portion 57c Inner cylindrical portion 57d Connection portion 58 Cooling stage 59 High temperature side electrode 60 Oxide superconducting current lead bulk 61 Heat shield plate 62 Copper current lead 63 GM refrigerator 66 Copper net line

Claims (3)

In an electrode structure used for a refrigerator-cooled superconducting magnet and provided at both ends of an oxide superconducting current lead connected to a superconducting coil to support and electrically connect the oxide superconducting lead, the oxide superconducting current lead A pair of caps attached to both ends; a pair of high-temperature side electrode connection portions and a low-temperature side electrode connection portion connected to one end of each of the pair of caps ; The one end side joined to the cap is made of a plate material provided with a flexible S-shaped portion bent twice in a U shape, and the connection portion of the low temperature side electrode is flexible U shape at one end side joined to the cap. made of a plate material having a site, the terminal portions connected to the connecting portion of the low-temperature side electrode has an L-shape, wherein the connecting portion of the high temperature side electrode S A terminal portion extending from the shape portion is formed, and at least one of the bent portion of the S-shaped portion and the bent portion of the U-shaped portion is provided with a slit made of at least one notch, An electrode structure of an oxide superconducting current lead , wherein the S-shaped portion and the U-shaped portion are provided at positions rotated 90 degrees around the central axis .   2. The electrode structure of the oxide superconducting current lead according to claim 1, wherein the U-shaped portions at both ends are provided so as to be displaced from each other around the central axis of the oxide superconducting current lead. Electrode structure of oxide superconducting current lead.   2. The oxide superconducting current lead electrode structure according to claim 1, wherein the cap is provided with at least two slits made of cuts provided in an axial direction.

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