JP2008159828A - Current lead, and superconducting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To evade a damage of an oxide superconducting material by difference of thermal shrinkage in a current lead using an oxide superconductor and a bypass conductor. <P>SOLUTION: The current lead has: a normal conduction current lead 1a which passes through a vacuum heat-insulating container 2 and is made of a fine conductive metal; an oxide superconductor 10 disposed in the vacuum heat-insulating container 2 for connecting the normal conduction current lead 1a with a superconducting apparatus 3; and a bypass conductor 20 disposed in the vacuum heat-insulating container 2 for connecting the normal conduction current lead 1a with the superconducting apparatus 3 electrically in parallel to the oxide superconductor 10. In the bypass conductor 20, a first conductor 21 made of a first metal material in which Young's modulus is relatively low and a coefficient of thermal conductivity and a conductivity are relatively high is mutually series-connected with a second conductor 22 made of a second metal material in which Young's modulus is relatively higher than the first metal material and the coefficient of thermal conductivity and the conductivity are relatively lower than that. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a current lead using an oxide superconductor and a superconducting device having such a current lead.

  The greatest feature of the superconducting phenomenon is that the electric resistance of the superconducting conductor becomes zero at the critical temperature, so that no heat is generated even when energized, so that a large current can flow without loss. A superconducting magnet device used in a superconducting power storage system is a typical device that applies this superconducting phenomenon.

  In a typical conventional superconducting magnet device, a superconducting magnet is housed in a heat shield of a vacuum heat insulating container called a cryostat, and the superconducting magnet is cooled by a refrigerator attached to the vacuum heat insulating container. This superconducting magnet device requires a current lead for supplying a current from a power source installed at room temperature to a superconducting magnet installed at a very low temperature. The current lead is connected to a normal conductive current lead made of a highly conductive metal and a superconductive current lead made of an oxide superconductor. The current lead is structured to be cooled by a refrigerator or a cooling medium.

Also, Patent Documents 1 and 2 disclose a technique for connecting a bypass conductor in parallel to a superconducting current lead in order to bypass the current and protect the superconducting current lead when quenching occurs in the superconducting current lead. Yes. The material of the bypass conductor is preferably a material having low thermal conductivity, and stainless steel or the like is suitable.
JP-A-8-32416 Japanese Patent Laid-Open No. 5-109531

  In general, a material having a low thermal conductivity such as stainless steel used for the bypass conductor has a relatively high Young's modulus. For this reason, for example, a tensile load is generated in the oxide superconductor due to a difference in thermal contraction accompanying cooling at the start of operation, and the oxide superconductor may be damaged.

  The present invention has been made in view of the above circumstances, and avoids damage to an oxide superconductor due to a difference in thermal shrinkage in a current lead using an oxide superconductor and a bypass conductor or a superconducting device employing the current lead. The purpose is to do.

  In order to achieve the above object, a current lead according to the present invention connects a superconducting device housed in a vacuum insulation container, cooled to a low temperature and placed in a superconducting state, and a power supply outside the vacuum insulation container. A current lead electrically insulated from the vacuum heat insulating container, the normal current conducting lead portion made of a good conductive metal penetrating the vacuum heat insulating container, and disposed in the vacuum heat insulating container An oxide superconducting conductor connecting the normal conducting current lead part and the superconducting device, and the normal conducting current lead part and the superconducting disposed in the vacuum heat insulating container and electrically parallel to the oxide superconducting conductor A bypass conductor for connecting to a device, wherein the bypass conductor includes a first conductor portion made of a first metal material having a relatively low Young's modulus and a relatively high thermal conductivity and conductivity. The first The second conductor portion Young's modulus as compared with the metal material has a relatively high thermal conductivity and the electrical conductivity of a relatively low second metallic material are connected in series with each other, and wherein.

  Further, the superconducting device according to the present invention connects a superconducting device cooled to a low temperature and placed in a superconducting state, a vacuum heat insulating container containing the superconducting device, a power source outside the vacuum heat insulating container, and the superconducting device. A current lead electrically insulated from the vacuum heat insulating container, wherein the current lead penetrates the vacuum heat insulating container and is made of a normal conductive current lead portion made of a highly conductive metal; and An oxide superconducting conductor that is disposed in a vacuum heat insulating container and connects the normal conductive current lead portion and the superconducting device, and is disposed in the vacuum heat insulating container and is electrically parallel to the oxide superconducting conductor. A bypass conductor that connects the normal conductive current lead portion and the superconducting device, and the bypass conductor has a relatively low Young's modulus and a relatively high thermal conductivity and conductivity. A first conductor portion made of one metal material, and a second conductor made of a second metal material having a relatively high Young's modulus and a relatively low thermal conductivity and conductivity compared to the first metal material. The body part is connected to each other in series.

  According to the present invention, in a current lead using an oxide superconductor and a bypass conductor or a superconducting device employing the current lead, damage to the oxide superconductor due to a difference in thermal shrinkage can be avoided or suppressed.

  Embodiments of a superconducting device according to the present invention will be described below with reference to the drawings.

  FIG. 1 is an elevational view showing a current lead and its periphery according to a first embodiment of the present invention. As shown in this figure, a superconducting device (for example, a superconducting magnet) 3 is accommodated in a vacuum heat insulating container 2. A power supply 30 for supplying current to the superconducting device 3 is disposed outside the vacuum heat insulating container 2. A current introduction terminal 8 is disposed through the upper portion of the vacuum heat insulating container 2, and the normal conductive current lead 1 a in the vacuum heat insulation container 2 and the power supply 30 are electrically connected via the current introduction terminal 8. The normal conductive current lead 1a is made of a highly conductive metal. The normal conductive current lead 1 a and the power supply 30 are electrically insulated from the vacuum heat insulating container 2 by the current introduction terminal 8.

  In the vacuum heat insulating container 2, the lower end of the normal conducting current lead 1a is connected to the high temperature end side electrode 11a. The high temperature end side electrode 11 a is made of a highly conductive metal and is disposed above the superconducting device 3. The oxide superconductor 10 is connected to the high temperature end electrode 11a. The oxide superconducting conductor 10 extends in the vertical direction, the upper end is connected to the high temperature end side electrode 11a, and the lower end is connected to the superconducting device 3 via the low temperature end side electrode 11b. The oxide superconducting conductor 10 is, for example, an oxide superconducting bulk material or an oxide superconducting thin film tape wire.

  The bypass conductor 20 bypasses the oxide superconducting conductor 10 and connects the high temperature end side electrode 11a and the low temperature end side electrode 11b. The bypass conductor 20 is formed by connecting a first conductor portion 21 connected to the high temperature end side electrode 11a and a second conductor portion 22 connected to the low temperature end side electrode 11b in series. The first conductor portion 21 is made of a metal material having a relatively low Young's modulus and a relatively high thermal conductivity and conductivity, such as copper or an alloy containing copper. On the other hand, the second conductor portion 22 is made of a metal material having a relatively high Young's modulus and a relatively low thermal conductivity and conductivity, for example, stainless steel, as compared with the first conductor portion 21. The first conductor part 21 and the second conductor part 22 are joined to each other by metallurgical joining such as welding or pressure welding. Each of the first conductor portion 21 and the second conductor portion 22 has at least one bent portion.

  A heat transfer plate 6 is attached to the high temperature end side electrode 11 a, and the heat transfer plate 6 is connected to the refrigerator 5 through an insulating plate 7. The refrigerator 5 is attached to the vacuum heat insulating container 2. The high temperature end side electrode 11 a is cooled by being thermally connected to the refrigerator 5 through the heat transfer plate 6 and the insulating plate 7. The superconducting device 3 may be cooled by the refrigerator 5 or the superconducting device 3 may be directly cooled by another refrigerator (not shown).

  According to this embodiment, when quenching occurs in the oxide superconductor 10, current bypasses the bypass conductor 20, and the oxide superconductor 10 can be protected. Further, since the bypass conductor 20 is made up of the first conductor portion 21 and the second conductor portion 22, the heat conduction is suppressed by the first conductor portion 21 having low thermal conductivity. In addition, distortion due to a difference in thermal contraction or thermal expansion between the oxide superconductor 10 and the bypass conductor 20 is mainly absorbed by the second conductor portion 22 having a low Young's modulus during cooling or temperature rise. For this reason, the load concerning the oxide superconductor 10 can be suppressed small, and damage can be avoided. Furthermore, each of the first conductor portion 21 and the second conductor portion 22 has a bent portion, so that the load applied to the oxide superconducting conductor 10 accompanying the contraction / expansion of the bypass conductor 20 can be reduced. Can do.

  The embodiments described above are merely examples, and the present invention is not limited to these.

  For example, the shape of the bypass conductor 20 is shown in a curved line in FIG. 1, but may be a spiral shape or a bellows surrounding the oxide superconducting conductor 10, for example.

  In the above embodiment, a superconducting magnet has been described as an example of the superconducting device 3 accommodated in the vacuum heat insulating container 2, but other superconducting devices may be used.

  Further, the vertical relationship in the description of the above embodiment is for convenience of description, and the present invention can be applied regardless of the direction of gravity.

1 is an elevation view showing a current lead and its periphery according to a first embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Current lead 1a ... Normal electric conduction current lead 2 ... Vacuum insulation container 3 ... Superconducting magnet (superconducting equipment)
5 ... Refrigerator 6 ... Heat transfer plate 7 ... Insulating plate 8 ... Current introduction terminal 10 ... Oxide superconducting conductor 11a ... High temperature end side electrode 11b ... Low temperature end side electrode 20 ... Bypass conductor 21 ... 1st conductor part 22 ... 2nd conductor part 30 ... Power supply

Claims (5)

A current lead electrically connected to a superconducting device housed in a vacuum insulation container, cooled to a low temperature and placed in a superconducting state, and a power supply outside the vacuum insulation container, and electrically insulated from the vacuum insulation container Because
A normal conductive flow lead portion made of a highly conductive metal that penetrates the vacuum insulation container;
An oxide superconducting conductor disposed in the vacuum insulation container and connecting the normal conducting current lead portion and the superconducting device;
A bypass conductor disposed in the vacuum heat insulation container and electrically connecting the normal conducting current lead portion and the superconducting device in parallel with the oxide superconducting conductor;
Have
The bypass conductor has a Young's modulus compared to the first metal material and the first conductor portion made of the first metal material having a relatively low Young's modulus and a relatively high thermal conductivity and conductivity. A current lead comprising: a second conductor portion made of a second metal material having a relatively high thermal conductivity and a relatively low electrical conductivity, connected in series to each other.   The current lead according to claim 1, wherein at least one of the first conductor portion and the second conductor portion has at least one bent portion.   The current lead according to claim 1, wherein the first conductor portion and the second conductor portion are metallurgically connected.   4. The current lead according to claim 1, wherein the first metal material is copper or an alloy containing copper, and the second metal material is stainless steel. 5. . A superconducting device that is cooled to a low temperature and placed in a superconducting state;
A vacuum insulation container for accommodating the superconducting device;
Connecting the power supply outside the vacuum insulation container and the superconducting device, and a current lead electrically insulated from the vacuum insulation container;
In a superconducting device having
The current lead is
A normal conductive flow lead portion made of a highly conductive metal that penetrates the vacuum insulation container;
An oxide superconducting conductor disposed in the vacuum insulation container and connecting the normal conducting current lead portion and the superconducting device;
A bypass conductor disposed in the vacuum heat insulation container and electrically connecting the normal conducting current lead portion and the superconducting device in parallel with the oxide superconducting conductor;
Have
The bypass conductor has a Young's modulus compared to the first metal material and the first conductor portion made of the first metal material having a relatively low Young's modulus and a relatively high thermal conductivity and conductivity. And a second conductor portion made of a second metal material having a relatively high thermal conductivity and relatively low electrical conductivity, connected in series to each other.

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