JPH05167107A - High-temperature superconducting current lead - Google Patents

Abstract

PURPOSE:To obtain a high-temperature superconducting current lead which stably functions and wherein a measure can be easily taken against quenching by cooling a high-temperature superconductor to a prescribed temperature with a refrigerating machine and constituting the main body of the current lead of the superconductor and a good conductor. CONSTITUTION:When a refrigerating machine 21 is actuated, the first- and second-stage cooling sections 21B and 21C of the machine 21 respectively become <=80K, and <=20K in temperature, cool the first and second main bodies 28 and 29 of the title current lead 20 to temperatures lower than their critical temperatures, and act as a first- and second-stage thermal anchors. An electric current is supplied from a power source to a superconducting coil 2 through a power source-side electrode terminal 22, first connection cooling plate 26, the lead main body 28, second cooling plate 27, and lead main body 29 and suppresses heat intrusion into a coolant section. Good conductors 28B and 29B respectively united with high-temperature superconductors 28A and 29A prevent the breakage of the leads by absorbing thermal stresses, etc., and, even when a quenching state occurs, the lead can maintain its function as a current lead, because the electric current bypasses the lead through the good conductors.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-temperature superconductor current lead. Particularly, by providing a thermal anchor by a refrigerator, the current lead body can be strengthened and prevented from being damaged, and intrusion heat can be reduced and quenching can be easily taken. The present invention relates to a high temperature superconductor current lead.

[0002]

2. Description of the Related Art A conventional superconducting coil device 1 is shown in FIG.
Based on this, an example will be described. The superconducting coil device 1 includes a superconducting coil 2, a coil container 3, a coolant 4 (for example, liquid helium) in the coil container 3, a heat shield plate 5, a cryostat container 6, a positive electrode current lead 7 and a negative electrode. For use, an external power source 9, a coil side connecting wire 10 and a power source side connecting wire 11, and a guide tube 12 covering the positive electrode current lead 7 and the negative electrode current lead 8.

The superconducting coil 2 is electrically connected to the external power source 9 by the positive electrode current lead 7, the negative electrode current lead 8, the coil side connecting wire 10 and the power source side connecting wire 11.

In the case of a gas cooling type current lead, the positive electrode current lead 7, the negative electrode current lead 8 and the coil side connecting wire are caused by the evaporating gas of the refrigerant 4 rising in the guide tube 12 as shown in the figure. 10 and the power supply side connecting wire 11 are cooled so that the heat entering from the outside can be suppressed.

However, the positive electrode current lead 7 and the negative electrode current lead 8 are wholly or partly made of a high temperature superconductor having a low thermal conductivity, for example, an oxide high temperature superconductor, and passed through these parts. It is possible to suppress the amount of heat invasion from the outside and the amount of Joule heat generation in the same portion to be low.

The oxide high-temperature superconductors include bismuth-based, yttrium-based, and thallium-based ones.

However, the high temperature oxide superconductor is difficult to be welded to different materials (difficulty in electrical and mechanical connection), has a low impact strength, etc., and exerts a force to attach the electrode terminal. However, there is a problem in that it is difficult (mechanical connection), and by attaching the electrode terminals to both ends thereof, it becomes an obstacle in forming a current lead.

Further, when the oxide high temperature superconductor current lead is incorporated in the superconducting coil device, there is a problem that the current lead body may be damaged due to thermal shock and external vibration due to insufficient strength.

Furthermore, when using a high-temperature superconductor, it is needless to say that it needs to be cooled to a critical temperature or lower.
There is a current lead according to 4-76707.

In this current lead, copper and an oxide high temperature superconductor are joined to form a current lead, and a cooling pipe for flowing liquid nitrogen is wound around the current lead to cool it. Alternatively, the joint between the superconductor and copper may be brought into direct contact with liquid nitrogen for cooling.

However, in this current lead, since liquid nitrogen, which is difficult to handle, is used, cooling of the current lead cannot be automated, and a reinforcing mechanism for the high temperature superconductor against thermal stress due to cooling is provided. However, there are various problems such as that it is difficult and that no current flows when the high temperature superconductor is quenched.

[0012]

The present invention has been made in view of the above problems, and in particular, a current lead using a high temperature superconductor such as an oxide high temperature superconductor which is in a superconducting state at a temperature of liquid nitrogen or higher. The current lead body can be cooled without using a cooling fluid such as liquid nitrogen, and the mechanical strength can be reinforced while ensuring the electrical connection between the superconducting coil side and the power source side electrode terminals. Therefore, it is an object of the present invention to provide a high-temperature superconductor current lead of stable performance which prevents damage, reduces intrusion heat, and is easy to prevent quenching.

[0013]

That is, according to the present invention, a high temperature superconductor such as an oxide high temperature superconductor is cooled to a predetermined temperature by a refrigerator such as a small Gifford McMahon refrigerator, and a current lead body is provided. Focusing on being composed of a high-temperature superconductor and a good conductor, a high-temperature superconductor current lead capable of electrically connecting a superconducting coil and an external power source, which is between the superconducting coil and the external power source. The placed refrigerator, the power source side electrode terminal attached to the room temperature side of the refrigerator via the first insulating flange, and the superconducting coil attached to the frozen portion of the refrigerator via the second insulating flange. And a current lead body that can be connected to the high temperature superconductor and a good conductor integrally combined with the high temperature superconductor. This conductor is a high temperature superconductor current lead the said current lead body, characterized in that the connectable to the power supply-side electrode terminal and the superconducting coil.

It is desirable that the good conductor is composed of a wire member and is connected at both ends thereof with slack.

[0015]

In the high-temperature superconductor current lead according to the present invention, since the high-temperature superconductor is connected to the cooling part of the refrigerator arranged between the superconducting coil and the external power source, the current lead body is cooled to a predetermined temperature. It is possible to maintain the superconducting state, suppress Joule heat generation, and suppress the invasion heat by the high-temperature superconductor having low thermal conductivity.

Further, since the current lead body is composed of the high-temperature superconductor and the good conductor, even if the superconducting state is broken, the current flows through the good conductor portion and the energized state of the superconducting coil can be maintained.

Further, by making the length of the good conductor longer than that of the high temperature superconductor and projecting at both ends, connection can be made at this good conductor portion, so that heat generated by temperature change at the connection portion with other parts. The good conductor expands and contracts in response to the contracting stress, and the mechanical and electrical connectivity can be maintained.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a high temperature superconductor current lead 20 according to an embodiment of the present invention will be described with reference to FIGS. 1 to 4 by taking as an example a case where a current lead body is made of an oxide high temperature superconductor. However, the same parts as those in FIG. 5 are designated by the same reference numerals, and the detailed description thereof will be omitted.

FIG. 1 is a perspective view of a high-temperature superconductor current lead 20. This high-temperature superconductor current lead 20 includes a refrigerator 21 such as a small Gifford-McMahon refrigerator and a power source side electrode terminal 22. , First insulating flange 23, second insulating flange 24, and insulating fixing material 25
, The first connection cooling plate 26, and the second connection cooling plate 27
And a first current lead body 28 and a second current lead body 29.

The refrigerator 21 is of a two-stage refrigeration type, and has an upper flange 21A and a first-stage cooling section 21B having a cooling temperature of 80K.
And a second stage cooling unit 21C having a cooling temperature of 20K.

The refrigerator 21 is fixed between the upper flange 21A and the cryostat container 6 via a first insulating flange 23.

Power supply side power terminal 22, first connection cooling plate 2
6 and the second connection cooling plate 27 are made of a good conductor such as silver, copper or aluminum.

The power supply side electrode terminal 22 is inserted and fixed in the fixing hole 23A of the first insulating flange 23.

The second insulating flange 24 is sandwiched and fixed between the first-stage cooling section 21B of the refrigerator 21 and the first connection cooling plate 26.

The first current lead body 28 is composed of a high temperature superconductor 28A made of an oxide high temperature superconductor and a good conductor 28B in the form of a wire made of a low resistance material such as silver or silver-plated copper or aluminum. To do.

The upper and lower ends of this good conductor 28B are fixed to the fixing holes 26A of the first connection cooling plate 26 and the second connection cooling plate 2, respectively.
7 are inserted into the fixing holes 27A and fixed by soldering.

The second current lead body 29 is composed of a high temperature superconductor 29A made of oxide high temperature superconductor, silver, and the like.
Alternatively, it is constituted by a wire-shaped good conductor 29B made of a low resistance material such as silver-plated copper or aluminum.

In the second-stage cooling section 21C of the refrigerator 21, the second connecting cooling plate 27 is fixed to the upper flange portion 25A of the insulating fixing material 25, and the upper and lower conductors 29B of the second current lead body 29 are arranged above and below. Both ends are respectively inserted into the fixing holes 27A of the second connection cooling plate 27 and the fixing holes 25C of the lower flange portion 25B and fixed by soldering.

Good conductor 29B of the second current lead body 29
Is connected to the superconducting coil 2.

The configuration of the first current lead body 28 or the second current lead body 29 is arbitrary, and the forming method thereof is CIP (hydrostatic isostatic pressing) or rolling, and the sintering method or partial melting is performed. The high-temperature superconductors 28A and 29A and the good conductors 28B and 29B are integrally molded by a melting method, a melting method, or the like.

The current lead body may have a cylindrical current lead body 30 shown in FIG. 3, a plate-shaped current lead body 31 shown in FIG. 4, or any other structure.

The good conductor 28A of the first current lead body 28 and the good conductor 29A of the second current lead body 29
The connecting portions to the first connection cooling plate 26, the second connection cooling plate 27, and the insulating fixing material 25 are each provided with slack.

Similarly, the portion of the power source side electrode terminal 22 between the first insulating flange 23 and the second insulating flange 24 is also provided with slack.

High-temperature superconductor current lead 2 having such a configuration
At 0, when the refrigerator 21 is started, the temperature of the first stage cooling unit 21B becomes 80 K or less within a few minutes, and the second stage cooling unit 2
When the temperature of 1C becomes 20 K or less, the first current lead body 28 and the second current lead body 29 are cooled to the critical temperature or less, and also function as the first-stage thermal anchor and the second-stage thermal anchor, respectively. ..

The current from the external power source 9 is supplied to the power source side electrode terminal 22, the first connection cooling plate 26, the first current lead body 28, the second connection cooling plate 27 and the second current lead body 29. It is supplied to the superconducting coil 2 through.

At this time, since the first current lead body 28 and the second current lead body 29 have no resistance to energization, there is no Joule heat generation, and the first current lead body 28 and the second current lead body 29 are present. Has a low thermal conductivity, and suppresses the heat entering the refrigerant 4 portion.

High temperature superconductor 28A and high temperature superconductor 2
Since the good conductor 28B and the good conductor 29B, which are integrally molded with 9A respectively, absorb thermal stress and the like, the high temperature superconductor 28A and the high temperature superconductor 29A during cooling and generation of electromagnetic force.
Will not be damaged.

In addition, the upper and lower connection ends of the good conductor 28B and the good conductor 29B and the power source side electrode terminal 22 have a slack, and the function of absorbing thermal stress can be improved.

Even if the high-temperature superconductor 28A or the high-temperature superconductor 29A is in the quench state and the current stops flowing, the high-temperature superconductor 28A and the good conductor 28B and the good conductor 29B integrally molded with the high-temperature superconductor 29A, respectively.
The current can be bypassed and the function as a current lead can be retained.

Even in the vicinity of the temperature 20K of the second-stage cooling section 21C, the first current lead body 28 and the second current lead body 29 are similarly cooled, so that the heat entering the superconducting coil 2 side is further increased. It's a small one.

Further, the refrigerator 21 has a power source side electrode terminal 2
2, first insulating flange 23, second insulating flange 24
And insulating fixing material 25, first connection cooling plate 26, second connection cooling plate 27, first current lead body 28, and second
Since the current lead body 29 is attached, the high-temperature superconductor current lead 20 can be compact and easy to use with the refrigerator 21 as the core and the positive and negative electrodes integrated.

Further, since the high-temperature superconductor 28A and the high-temperature superconductor 29A are used, it is possible to reduce the heat entering from the outside as described above, and

The first current lead body 28 and the second connection cooling plate 27 and the second connection cooling plate 27 are interposed.
Since the current lead main bodies 29 are attached, it is possible to secure a mechanical reinforcing mechanism for these current lead main bodies 28, 29.

Moreover, when the high temperature superconductor 28A and the high temperature superconductor 29A are in the quench state, the good conductor 2
Since the bypass circuit is formed on the side of 8B and the good conductor 29B, the energized state is maintained and it is safe.

In the high temperature superconductor current lead 20 according to the above embodiment, the cooling temperature of the refrigerator 21 is 80K.
Although the first-stage thermal anchor by the first-stage cooling unit 21B and the second-stage thermal anchor by the second-stage cooling unit 21C having the cooling temperature of 20K are provided, the second-stage thermal anchor may be omitted.

Further, the number of high temperature superconductors used as the current lead body is arbitrarily selected according to the required current.

[0047]

As described above, according to the present invention, since the refrigerator is used and the current lead body is composed of the high temperature superconductor and the good conductor, it is compact and easy to handle, and the high temperature superconductor is reinforced and damaged. It is possible to obtain a high-reliability high-temperature superconductor current lead capable of preventing invasion heat from the outside and facilitating quenching measures as well as prevention.

[0048]

[Brief description of drawings]

FIG. 1 is a perspective view of a high temperature superconductor current lead 20 according to one embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of a high temperature superconductor current lead 20 of the same.

FIG. 3 is a perspective view of a cylindrical current lead body 30 of the same.

FIG. 4 is a perspective view of a plate-shaped current lead body 31 of the same.

FIG. 5 is a schematic view of a conventional superconducting coil device 1.

[Explanation of symbols]

1 Superconducting Coil Device 2 Superconducting Coil 3 Coil Container 4 Refrigerant (Liquid Helium) 5 Heat Shield Plate 6 Cryostat Container 7 Positive Current Lead 8 Negative Current Lead 9 External Power Supply 10 Coil Side Connection Wire 11 Power Supply Side Connection Wire 12 Guide Tube 20 High-temperature superconductor current lead 21 Refrigerator (small Gifford-McMahon refrigerator) 21A Upper flange 21B of refrigerator 21B First-stage cooling section of refrigerator 21 21C Second-stage cooling section of refrigerator 21 Power-side electrode terminal 23 No. 1 Insulation flange 23A Fixing hole of first insulation flange 23 24 Second insulation flange 25 Insulation fixing material 25A Upper flange part of insulation fixing material 25B Lower flange part of insulation fixing material 25C Fixing hole of insulation fixing material 25 26 1st connection cooling plate 26A 1st connection cooling plate 26 fixing hole 27 2 Connection cooling plate 27A Fixing hole of second connection cooling plate 27 28 First current lead body (high temperature superconductor current lead) 28A High temperature superconductor of first current lead body 28 28B First current lead body 28 Good conductor 29 second current lead body (high-temperature superconductor current lead) 29A high-temperature superconductor 29B of second current lead body 29B good conductor of second current lead body 29 cylindrical current lead body 31 plate-shaped current Lead body

Claims (1)

[Claims] 1. A high temperature superconductor current lead capable of electrically connecting a superconducting coil and an external power source, the refrigerator being arranged between the superconducting coil and the external power source, and a room temperature of the refrigerator. A power source side electrode terminal attached to the side of the refrigerator via a first insulating flange, and a current lead body attachable to the freezing portion of the refrigerator via a second insulating flange and connectable to the superconducting coil. The current lead body is composed of a high-temperature superconductor and a good conductor integrally combined with the high-temperature superconductor, and the good conductor enables the current lead body to be connected to the power source side electrode terminal and the superconducting coil. A high temperature superconductor current lead characterized in that 1. The high-temperature superconductor current lead according to claim 1, wherein the good conductor is composed of a wire member and is connected so as to have slack at both ends thereof.