JP3284406B2 - Superconducting wire connecting device for cryogenic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for connecting a superconducting wire for a cryogenic device, and more particularly to a cryogenic device for connecting current leads (superconducting wires) for supplying a current to a cryogenic device such as a superconducting coil. The present invention relates to a superconducting wire connecting device.

[0002]

2. Description of the Related Art Conventional superconducting coils or superconducting magnets,
A current lead made of a superconducting wire or the like is connected to supply current to a low-temperature device represented by a superconducting device such as a nuclear magnetic resonance apparatus (MRI), a wiggler, or an accelerator. In particular, by using an oxide superconducting current lead, a refrigerator-cooled superconducting magnet or the like that does not employ liquid helium as a refrigerant has become possible. However, when it is necessary to interpose a normal conducting part at the connection between the low-temperature device and the current lead, holding the current lead in the vacuum of the vacuum vessel suppresses heat intrusion due to convection or heat conduction, In some cases, the device is configured to be held in a refrigerant atmosphere or a certain gas atmosphere. For example, there is JP-A-7-297455.

An outline will be given based on FIG. 3 and FIG. FIG.
1 is a cross-sectional view of a superconducting coil device 1. The superconducting coil device 1 includes a cryostat container 2 serving as an adiabatic vacuum container and a refrigerant 3 contained in the cryostat container 2.
(For example, liquid helium), a vacuum vessel 4, an external power supply device 5, a current supply wire 6, a superconducting coil 7, and a multi-stage cooling stage type small refrigerator such as a GM refrigerator (Gifford McMafon refrigerator) 8. And The current supply wire 6 is a metal current lead body 9 made of a copper material or the like.
And a first current lead 10, a second current lead 11, and a superconducting coil side terminal 12 each made of a superconducting wire.
And a superconducting coil-side superconducting wire 13.

At the first cooling stage 8 A of the GM refrigerator 8, the metal current lead body 9 and the first current lead 10 are connected to the second cooling stage 8 of the GM refrigerator 8 by the high-temperature side connection portion 14. In the portion 8B, the first current lead 10 and the second current lead 11 are connected by the intermediate connecting portion 15, and the second current lead 11 and the superconducting coil side terminal 12 are connected by the low temperature side connecting portion 16, respectively. Make an electrical connection.

A first ceramic plate 17 is interposed between the first cooling stage 8A of the GM refrigerator 8 and the high-temperature side connection portion 14, and the second cooling stage 8B and the intermediate connection portion 15 of the GM refrigerator 8 are interposed. , A second ceramic plate 18 is interposed between the second ceramic plate 18 and the bottom wall surface of the vacuum vessel 4 and the low-temperature side connection portion 16.
Are in thermal contact with each other with a third ceramic plate 19 interposed therebetween. Note that a cooling transmission member 20 is interposed between the refrigerant 3 and the superconducting coil side terminal 12.

In the superconducting coil device 1 having such a configuration, by employing the GM refrigerator 8 and the current supply wire 6, the temperature of the external power supply device 5 can be reduced from the temperature range of 300K.
For example, the first cooling stage 8A is cooled to a temperature of 70K, the second cooling stage 8B is cooled to a temperature of 15K, and the third ceramic plate 19 is cooled to a temperature of 4K to maintain the superconducting coil 7 at a predetermined cryogenic temperature. be able to.

FIG. 4 is an enlarged sectional view of a connection portion 21 at the bottom (third ceramic plate 19) of the vacuum container 4, and conventionally, as shown in the drawing, the third ceramic plate 19
May be inserted into the through-hole 4A of the vacuum container 4, the superconducting coil side terminal 12 may be inserted into the through-hole 19A of the third ceramic plate 19, and sealing may be performed with a resin material 22, a solder material 23, or the like.

However, the structure of the connecting portion 21 is complicated, and the resin material 22 at extremely low temperatures.
And that the solder material 23 does not easily maintain airtightness due to heat shrinkage. If the critical current is as large as 500 amperes, for example, it is necessary to pass a plurality of superconducting coil side terminals 12 through the third ceramic plate 19. When the pressure difference between the inner layer (inside the vacuum vessel 4) and the outer layer (outside the vacuum vessel 4) is large, there is a problem that the airtightness of the vacuum vessel 4 cannot be ensured.

[0008] Even if the current supply wire 6 is not cooled by the GM refrigerator 8 as described above, a part (current lead) is accommodated in the vacuum vessel 4 to connect the superconducting coil 7 to the current lead. When a normal conducting portion needs to be interposed in the portion, the current supply wire 6 is held in the vacuum of the vacuum vessel 4, and the superconducting coil 7 is held in the refrigerant 3 atmosphere or a certain gas atmosphere. As described above, it is necessary to maintain airtightness or pressure resistance at the connection portion.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and is intended for a low-temperature device capable of reducing heat penetration into a superconducting coil or other refrigerant (liquid helium) for cooling a low-temperature device. It is an object to provide a connection device for a superconducting wire.

Further, the present invention provides a connecting device for a superconducting wire for a low-temperature device capable of suppressing Joule heat generation at a connecting portion between a current supply wire such as a current lead and the low-temperature device and reducing heat penetration into the low-temperature device. That is the task.

Another object of the present invention is to provide a connection device for a superconducting wire for low-temperature equipment, which can maintain the airtightness and pressure resistance of a vacuum vessel containing a current supply wire such as a current lead.

Another object of the present invention is to provide a connecting device for a superconducting wire for a low-temperature device, which can supply electricity at a very low temperature particularly when a large-capacity current is supplied.

[0013]

That is, the present invention does not form a portion of a through hole through which a superconducting wire is directly inserted at a connection portion for connecting at least a pair of superconducting wires in a current lead or other forms. Of the superconducting wire and the second superconducting wire can be connected via a current terminal for connection, and electrically connected to an external power supply device arranged outside the cryostat container, and inside the vacuum container. A cryogenic device superconducting device for connecting the accommodated first superconducting wire and a second superconducting wire immersed in a refrigerant in the cryostat container and electrically connected to a cryogenic device separated from the vacuum container. A connection device for a wire, wherein at least one of the first superconducting wire and the second superconducting wire is embedded and electrically connected. A connection current terminal for forming an embedding hole that can be connected and penetrating the vacuum vessel, and an insulating member for fixing the connection current terminal to the vacuum vessel are provided. A connection device for a superconducting wire for a low-temperature device, wherein the other of the first superconducting wire or the second superconducting wire can be electrically connected to a current terminal.

The embedding hole may be prevented from passing through the vacuum vessel at the connection current terminal.

[0015] At least one of the first superconducting wire and the second superconducting wire can be connected in parallel to the connection current terminal.

A metal O-ring or other metal sealing member may be provided between the insulating member and the vacuum vessel.

A fixing member such as a fixing bolt for fixing the insulating member to the vacuum vessel can be provided.

The first embedding hole and the second embedding hole , which are not in communication with each other, have an overlapping portion in the longitudinal direction of the first superconducting wire and the second superconducting wire. to form a buried cavity in said first these first embedding hole and the second embedding hole 1
And the second superconducting wire can be electrically connected to each other.

In the connection device for a superconducting wire for a low-temperature device according to the present invention, an embedding hole for embedding at least one of the first superconducting wire and the second superconducting wire to be electrically connected is formed. The connecting current terminal is provided through the vacuum vessel, and the other of the first superconducting wire or the second superconducting wire can be connected to the connecting current terminal. Therefore, the first and second superconducting wires are connected to each other by vacuum. Rather than penetrating and connecting through the wall surface of the container, it is electrically connected via this connection current terminal.
Further, since the connection current terminal itself is fixed to the vacuum vessel via an insulating member such as an insulation insulator, a connection portion having excellent airtightness and pressure resistance can be formed.

Therefore, unlike the prior art, the use of a resin material or a solder material that causes thermal shrinkage at an extremely low temperature is avoided in the through-hole itself formed in the vacuum vessel, and this connection current terminal is fixed to the vacuum vessel. The superconducting wires such as the superconducting coil side terminals and other current leads can be connected to each other in a state where the airtight state is effectively maintained by the insulating member, thereby suppressing heat intrusion due to convection to the current supply wire in the vacuum vessel. In addition to the above, it is possible to reduce heat intrusion into the refrigerant via the current supply wire or due to Joule heat.

[0021]

Next, a connection device 30 for a superconducting wire for low-temperature equipment according to a first embodiment of the present invention will be described with reference to FIG. However, the same parts as those in FIGS. 3 and 4 are denoted by the same reference numerals, and detailed description thereof will be omitted. FIG. 1 is an enlarged cross-sectional view of a connection device 30 for a superconducting wire for a low-temperature device.
Insulating insulator 31 (insulating member) and connecting current terminal 32
And

The insulating insulator 31 is made of a circular ceramic plate or the like, and has a fixing through hole 3 at the center thereof.
1A, and a connecting current terminal 32 is formed in the fixing through hole 31.
And the space between them is fixed in an airtight state.

The insulating insulator 31 has a metal O-ring 33 or the like (metal sealing member) interposed between the insulating insulator 31 and the vacuum vessel 4 and a fixing bolt 34 attached to a predetermined portion on the peripheral surface thereof.
(Fixing member) is fixed to the vacuum vessel 4 in a close contact state.

The connection current terminal 32 is formed with an opening 32A having a predetermined depth from the inside (vacuum space side) of the vacuum vessel 4 and, for example, the superconducting coil side terminal 12 is formed in the hole 32A. A first superconducting wire 35 (FIG. 3) or the like is inserted therethrough, fixed with a solder material 36, and electrically connected.

A second superconducting wire 37 (for example, the superconducting coil-side superconducting wire 13) is electrically connected to a portion of the connection current terminal 32 protruding toward the superconducting coil 7 by a solder material 36 or the like.

In the connecting device 30 for a superconducting wire for a low-temperature device having such a configuration, the embedding hole 32A for connecting the first superconducting wire 35 does not penetrate through the vacuum vessel 4 to the outside thereof. External refrigerant 3
The gas tightness is maintained between the gas space and the vacuum space, and the vacuum vessel 4 can have a pressure-resistant structure. Therefore,
The vacuum state in the vacuum vessel 4 can be maintained extremely well, and the heat intrusion through the first superconducting wire 35 due to the convection can be effectively suppressed, and the first superconducting wire 35 can be effectively prevented.
Good electrical connection between the solder material 36 and the solder material 36 can be realized. Further, the work of soldering the first superconducting wire 35 and the connection current terminal 32 is easy.

The size of the embedding hole 32A is selected, and the first superconducting wire 3 is selected in accordance with the current carrying capacity.
5 can be freely selected in size or form.

Further, current flows through the first superconducting wire 35 and the solder material 36, and the non-penetrating region 32B, which is the normal conducting portion of the connecting current terminal 32, is extremely small. Intrusion heat is
The resistance heat generation is reduced as compared with the case where there is resistance heat generation.

As shown by the phantom line in FIG. 1, an embedding hole 32C having the same structure is formed on the opposite side of the embedding hole 32A of the connection current terminal 32, and the non-penetrating region 32 is formed.
It is also possible to reduce B and electrically connect the second superconducting wire 36 to this embedding hole 32C after inserting it. In short, in the present invention, the hole for embedding may be opened from the outside of the vacuum vessel 4 (on the superconducting coil 6 side), and even if it is formed from both inside and outside, the holes are not in communication with each other. It is good.

FIG. 2 is an enlarged sectional view of a connecting device 40 for a superconducting wire for low-temperature equipment according to a second embodiment of the present invention. 32, a first embedding hole 41 and a second embedding hole 42 are formed from both inside and outside of the vacuum vessel 4. However, the first embedding hole 41
And the second embedding hole 42 are not in communication with each other, and the first superconducting wire 35 and the second superconducting wire 37
Has an overlapping portion 43 in the length direction.

The connection device 40 for a superconducting wire for a low-temperature device having such a configuration can also connect the first superconducting wire 35 and the second superconducting wire 37 maintaining the airtightness and pressure resistance in the vacuum vessel 4 portion. At the same time, Joule heat generation in the overlapping portion 43 can be extremely reduced, and the amount of heat entering the refrigerant 3 and the superconducting coil 7 can be reduced.

[0032]

As described above, according to the present invention, since the insulating member and the current terminal for connection are used, the insulating member and the current terminal for connection are not penetrated through the burying hole formed in the current terminal for connection, and the pressure resistance and airtightness are improved. An excellent superconducting wire connection structure can be realized.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a connection device 30 for a superconducting wire for a low-temperature device according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a connection device 40 for a superconducting wire for a low-temperature device according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view of a conventional superconducting coil device 1.

FIG. 4 is an enlarged sectional view of a connection portion 21 of a bottom portion (third ceramic plate 19) of the vacuum vessel 4;

[Explanation of symbols]

REFERENCE SIGNS LIST 1 superconducting coil device (FIG. 3) 2 cryostat container 3 refrigerant (for example, liquid helium) 4 vacuum container 4A through hole of vacuum container 4 (FIGS. 1, 2 and 4) 5 external power supply device 6 current supply wire 7 superconducting coil 8 GM refrigerator (Gifford McMahon refrigerator) 8A First cooling stage of GM refrigerator 8 8B Second cooling stage of GM refrigerator 8 9 Metal current lead body 10 First current lead 11 Second current lead DESCRIPTION OF SYMBOLS 12 Superconducting coil side terminal 13 Superconducting coil side superconducting wire 14 High temperature side connection part 15 Intermediate connection part 16 Low temperature side connection part 17 First ceramic plate 18 Second ceramic plate 19 Third ceramic plate 19A Third ceramic plate 19 20 Cooling transmission member 21 Connection part 22 Resin material 23 Solder material 30 For low temperature equipment Superconducting wire connecting device (first embodiment, FIG. 1) 31 Insulating insulator (insulating member) 31A Fixing through hole of insulating insulator 31 32 Connection current terminal 32A Embedding hole 32B of connection current terminal 32 Connection non transmembrane region 32C embedding hole 32A opposite embedding hole 33 a metal O-ring and the connecting current terminal 32 (the metal seal member) 34 fixed bolts use current terminal 32 (fixing member) 35 second 1 superconducting wire 36 solder material 37 second superconducting wire 40 connecting device for superconducting wire for low-temperature equipment (second embodiment, FIG. 2) 41 first embedding hole 42 second embedding hole 43 Overlapping portions in the length direction of the first embedding hole 41 and the second embedding hole 42

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-297455 (JP, A) JP-A-3-20911 (JP, A) JP-A-1-160671 (JP, U) (58) Survey Field (Int.Cl. ⁷ , DB name) H01R 4/68 H01B 12/00 H01F 6/06 H01L 39/04

Claims (6)

(57) [Claims] 1. The vacuum container and the refrigerant are separated from each other.
Before as well as electrically connected to an external power supply arranged outside the cryostat vessel containing therein while
A first superconducting wire accommodated in the serial vacuum vessel, and a second superconducting wire which is electrically connected to the low-temperature apparatus in a state in which isolated from said vacuum chamber while immersed in the coolant in the cryostat vessel The vacuum container
A connection device for a superconducting wire for a low-temperature device connected at a connection portion between the superconducting wire and the refrigerant , wherein at least one of the first superconducting wire or the second superconducting wire is embedded and electrically connected. And the vacuum vessel side and the refrigerant side
Yes forming a buried cavity in which is not in communication, and the connection current terminal provided through the vacuum chamber, and an insulating member for fixing the connection current terminal to said vacuum vessel, provided with a said A connection device for a superconducting wire for a low-temperature device, wherein the other of the first superconducting wire or the second superconducting wire can be electrically connected to a connection current terminal. 2. The connection device for a superconducting wire for a low-temperature device according to claim 1, wherein the embedding hole does not penetrate through the vacuum vessel at the connection current terminal. 3. The low-temperature equipment according to claim 1, wherein at least one of the first superconducting wire and the second superconducting wire is connected in parallel to the connection current terminal. Superconducting wire connection device. 4. The superconducting wire connecting device for a low-temperature device according to claim 1, wherein a metal sealing member is provided between the insulating member and the vacuum vessel. 5. The superconducting wire connecting device for a low-temperature device according to claim 1, further comprising a fixing member for fixing the insulating member to the vacuum vessel. 6. A first embedding hole which is not communicated with the connection current terminal and has an overlapping portion in a length direction of the first superconducting wire and the second superconducting wire. > unit and to form a second embedding hole, these first embedding hole and a second of said the embedding hole first superconducting wire and the second superconducting wire, respectively electrically The connection device for a superconducting wire for a low-temperature device according to claim 1, wherein the connection is performed.