JP2686210B2 - Superconducting coil device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forced cooling type superconducting coil device for connecting a refrigerant pipe to a conduit and forcibly cooling the superconducting coil.

[0002]

2. Description of the Related Art FIG. 5 shows, for example, "11th International Conference On Magnet Te
chnology) ”(1989) pages 847 to 851, which is a refrigerant piping connection diagram of the conventional superconducting coil device.

In the figure, 1 is a superconducting coil formed by using a superconducting conductor in which a wire bundle containing a superconducting element wire is housed in a metal conduit, and 2 is a superconducting coil 1 which is forcibly cooled to achieve criticality. A refrigerant supply pipe 3 serving as a refrigerant pipe for supplying helium as a refrigerant to the superconducting coil 1 in order to keep the temperature below the temperature is a refrigerant discharge pipe serving as a refrigerant pipe for discharging the refrigerant.

Next, the operation will be described. For example Nb
₃ Superconducting conductors using compound superconductors such as Sn are
It is coiled at room temperature without the Nb ₃ Sn formation chemical reaction. The coiled superconducting conductor is N
In order to cause the b ₃ Sn formation chemical reaction, heat treatment is performed at a high temperature of about 700 ° C. for several tens hours. After such heat treatment,
The superconducting coil 1 is completed by applying electrical insulation.

The superconducting coil 1 as described above is used after being cooled to a cryogenic temperature of about -269 ° C. by a coolant such as helium. Helium, which is a refrigerant, is supplied from the refrigerant supply pipe 2 and flows inside the superconducting coil 1, and another helium discharge pipe 3 is provided.
Is more exhausted.

By the way, the Nb ₃ Sn compound-based superconductor is extremely vulnerable to mechanical strain, and its superconducting property is significantly deteriorated by applying a slight strain of, for example, 0.5%, and the critical current density which is an index of current capacity is about. It will be reduced to 50%.

The largest element of the strain generated in the superconducting conductor of the superconducting coil 1 as described above is the thermal strain generated during cooling due to the difference in the material forming the conductor. Normal,
The material used for the conduit is, for example, SUS304L
It is an austenitic stainless steel such as, but this material has a heat shrinkage ratio of about 1.6% from Nb ₃ Sn formation heat treatment temperature of about 700 ° C to superconducting coil 1 use temperature of about -269 ° C. Yes, the thermal contraction rate of Nb ₃ Sn in the same temperature range is greater than about 0.7%. That is, a maximum of about 0.9% of thermal strain, which is the difference in thermal contraction rate, acts on Nb ₃ Sn, which is a superconductor.

Recently, in order to prevent deterioration of superconducting properties due to this thermal strain, the use of titanium as a conduit material has been studied and prototyped as an advanced technology. in this case,
In the process of manufacturing the superconducting coil 1,
A titanium refrigerant terminal tube 5 and a current terminal (not shown) are attached. Then, when the superconducting coil 1 is installed in an operating device such as an adiabatic vacuum container at the installation site, the refrigerant supply pipe 2 and the refrigerant discharge pipe 3 are connected to the refrigerant terminal pipe 5 at the joint portion 4 shown in FIG.

As described above, even when titanium is used as the conduit material, austenitic stainless steel pipes are used for the coolant supply pipe 2 and the coolant discharge pipe 3 in terms of ease of welding and cost. There is. For this reason,
The connection between the refrigerant pipes 2 and 3 and the refrigerant terminal pipe 5 is a dissimilar metal connection between titanium and austenitic stainless steel.

Although a reliable method of connecting metals even at extremely low temperatures is usually welding, welding of titanium and austenitic stainless steel is extremely difficult. The connection with the pipe 5 must be by mechanical pipe connection, such as a bite type joint.

[0011]

In the conventional superconducting coil device as described above, the refrigerant pipes 2 and 3 and the refrigerant terminal pipe 5 are connected by a mechanical pipe connection. The connection method is such that when the pipe diameter is large, such as more than 1 cm, or when the temperature is significantly different between construction and use, such as cryogenic piping, the biting part loosens due to heat shrinkage, However, there is a risk that the refrigerant gas may leak.

The present invention has been made to solve the above problems, and it is possible to improve the pressure tightness and reliability of the connection between the refrigerant pipe and the conduit, An object of the present invention is to obtain a superconducting coil device capable of preventing gas leakage.

[0013]

According to a first aspect of the present invention, there is provided a superconducting coil device in which a material on the conduit side is the same metal as the conduit, and a material on the refrigerant pipe side is a dissimilar metal joint made of austenitic stainless steel. , A conduit and a refrigerant pipe are connected.

In a superconducting coil device according to a second aspect of the present invention, the material of the conduit side is the same metal as the conduit, the material of the refrigerant piping side is austenitic stainless steel, and the electrically insulating tube is hermetically sealed between these dissimilar metals. The conduit and the refrigerant pipe are connected to each other through a dissimilar metal insulation joint that is inserted between the conduit and the refrigerant pipe.

[0015]

According to the invention of claim 1, by using the dissimilar metal joint in which dissimilar metals are connected in advance by a method having excellent airtightness, connection between dissimilar metals can be performed at the stage of manufacturing parts and conduit Also, the refrigerant pipe and the dissimilar metal joint are connected between the same kind of metal, and the pressure-proof airtight reliability is improved as a whole.

According to the second aspect of the present invention, the electric insulation pipe is inserted between the different kinds of metals, so that the electric insulation between the superconducting coil side and the operating device side is performed at the joint portion.

[0017]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. Embodiment 1 FIG. FIG. 1 is a refrigerant pipe connection diagram of a superconducting coil device according to an embodiment of the present invention. The same or corresponding parts as in FIG. 5 are designated by the same reference numerals, and the description thereof will be omitted.

In the figure, 11 is a dissimilar metal joint interposed between the coolant supply pipe 2 and the coolant discharge pipe 3 and the coolant terminal pipe 5, respectively. This dissimilar metal joint 11 is enlarged in FIG. As shown, conduit made of the same metal as the conduit,
That is, it is composed of a titanium pipe 11a and a pipe made of the same metal as the refrigerant pipes 2 and 3, that is, an austenitic stainless steel pipe 11b.

The titanium pipe 11a and the austenitic stainless steel pipe 11b are previously joined at the stage of manufacturing the parts. As such a dissimilar metal joining method,
For example, there are diffusion bonding, brazing, pressure welding, etc., but any method may be adopted as long as it has excellent mechanical strength and ductility of the bonded portion and excellent pressure tightness, and the same effect can be obtained. .

As described in the conventional example, for example, Nb ₃ S
In the superconducting coil 1 that uses a compound superconductor such as n, titanium is used as the conduit material in order to prevent thermal strain during cooling due to the difference in conduit material from being applied to the superconducting conductor and deterioration of superconducting characteristics. The titanium refrigerant terminal tube 5 is attached to the conduit during the coil manufacturing process. The mechanism for cooling the superconducting coil 1 and generating strain is the same as in the case of the conventional example.

When the coil is used alone, the titanium refrigerant terminal tube 5 of the superconducting coil 1 and the dissimilar metal joint 1 are used in the factory.
The titanium pipe 11a of No. 1 is hermetically welded. Oxygen removal from the ambient atmosphere is extremely important for titanium welding, but when welding is carried out in a factory, it is easy to control the welding conditions, so a high quality titanium welded joint can be obtained.

After that, when the superconducting coil 1 is installed in the operating device at the installation site, the austenitic stainless steel pipe 11b of the dissimilar metal joint 11 is connected to the refrigerant pipe, that is, the refrigerant supply pipe 2 or the refrigerant discharge pipe 3. To be done. Since the stainless steel pipes are easily airtightly welded to each other, there is no problem in quality.

As described above, in the superconducting coil device of the first embodiment, the dissimilar metal joint 11 is interposed between the refrigerant pipes 2 and 3 on the operating device side and the refrigerant terminal pipe 5 on the coil side. Improves the pressure tightness reliability of this connection part,
Leakage of refrigerant gas is prevented.

Next, FIG. 3 is a refrigerant piping connection diagram of a superconducting coil device according to an embodiment of the present invention. In the figure, reference numeral 12 is a dissimilar metal insulation joint interposed between the coolant supply pipe 2 and the coolant discharge pipe 3 and the coolant terminal pipe 5, respectively. This dissimilar metal insulation joint 12 has a cross section enlarged in FIG. As shown, it comprises a titanium pipe 12a, an austenitic stainless steel pipe 12b, and an electrical insulation pipe 12c interposed between these dissimilar metals. The electrical insulating tube 12c is made of an insulating material such as FRP or ceramics.

The pipes 12a to 12c forming the dissimilar metal insulation joint 12 are preliminarily joined at the stage of parts. Examples of this joining method include adhesion and brazing, but any method may be adopted as long as it has excellent mechanical strength of the joined portion and excellent pressure tightness, and the same effect can be obtained. To be

In the superconducting coil device according to the second embodiment, as in the case of the first embodiment, the titanium refrigerant terminal tube 5 of the superconducting coil 1 and the titanium pipe 12a of the dissimilar metal insulation joint 12 are used in the factory when the coil is alone. And are hermetically welded.
When the superconducting coil 1 is installed in the driving device at the installation site, the refrigerant pipe, that is, the refrigerant supply pipe 2 or the refrigerant discharge pipe 3 is connected to the austenitic stainless steel pipe 12b of the dissimilar metal insulation joint 12.

Therefore, similarly to the first embodiment, the pressure tightness and reliability of the connection between the refrigerant pipes 2 and 3 on the operating device side and the refrigerant terminal pipe 5 on the coil side is improved, and in this portion, This will prevent the refrigerant gas from leaking.

By the way, the conduit of the superconducting coil 1 is in electrical high voltage because it is in contact with the current path. On the other hand, since the potentials of the refrigerant pipes 2 and 3 are the same as the ground, it is necessary to electrically insulate the coil side pipe and the operating device side pipe. There are various methods for insulating the pipe, but when electrically insulating in the vicinity of the superconducting coil 1, the insulating structure shown in FIG. 3 is required. The second embodiment is used in such a case.

That is, by using the dissimilar metal insulation joint 12 as shown in the second embodiment, at the same time as the connection between the refrigerant pipes 2 and 3 on the operating device side and the refrigerant terminal pipe 5 on the coil side, Electrical insulation between the two can also be performed, and as a result, the number of parts can be reduced and the assembling workability can be improved.

The material of the dissimilar metal joint 11 and the dissimilar metal insulating joint 12 on the conduit side may be determined according to the material of the conduit, and is not limited to titanium.

[0031]

As described above, in the superconducting coil device according to the invention of claim 1, the material of the conduit side is the same metal as the conduit, and the material of the refrigerant pipe side is the austenitic stainless steel joint. Since the conduit and the refrigerant supply pipe are connected to each other, it is possible to connect the dissimilar metals while maintaining the airtightness at the stage of manufacturing the parts, and to connect the refrigerant terminal pipe, that is, the conduit and the dissimilar metal joint, and for the refrigerant. The connection between the pipe and the dissimilar metal joint can be the same kind of metal connection, therefore the pressure tightness and reliability of the connection between the refrigerant pipe and the conduit can be improved and the leakage of the refrigerant gas can be prevented. There is an effect that can be done.

In the superconducting coil device according to the second aspect of the present invention, the material of the conduit side is the same metal as the conduit, the material of the refrigerant piping side is austenitic stainless steel, and an electrically insulating pipe is provided between these dissimilar metals. Since the conduit and the refrigerant pipe are connected through a dissimilar metal insulating joint that is airtightly inserted, in addition to the same effect as the invention of claim 1, the conduit and the refrigerant pipe are connected at the same time. It is possible to electrically insulate between them, and it is possible to reduce the number of parts and improve assembly workability.

[Brief description of the drawings]

FIG. 1 is a connection diagram of a refrigerant pipe of a superconducting coil device according to an embodiment of the present invention.

FIG. 2 is an enlarged perspective view showing the dissimilar metal joint of FIG.

FIG. 3 is a connection diagram of a refrigerant pipe of a superconducting coil device according to an embodiment of the present invention.

4 is a cross-sectional view of the dissimilar metal insulated joint of FIG.

FIG. 5 is a connection diagram of a refrigerant pipe of an example of a conventional superconducting coil.

[Explanation of symbols]

 1 Superconducting Coil 2 Refrigerant Supply Pipe (Refrigerant Pipe) 3 Refrigerant Discharge Pipe (Refrigerant Pipe) 5 Refrigerant Terminal Pipe 11 Different Metal Joint 12 Different Metal Insulation Joint

Claims (2)

(57) [Claims] 1. A superconducting coil using a superconducting conductor in which a wire bundle containing a superconducting element wire is housed in a metal conduit, and a refrigerant terminal tube of the conduit for forced cooling of the superconducting coil. In a superconducting coil device having a refrigerant pipe, the material of the conduit side is the same metal as the conduit, and the material of the refrigerant pipe side is a dissimilar metal joint made of austenitic stainless steel, and the conduit is A superconducting coil device, which is connected to the refrigerant pipe. 2. A superconducting coil using a superconducting conductor in which a wire bundle containing a superconducting element wire is housed in a metal conduit, and a refrigerant terminal tube of the conduit for forced cooling of the superconducting coil. In a superconducting coil device having a refrigerant pipe, the material of the conduit side is the same metal as the conduit, the material of the refrigerant pipe side is austenitic stainless steel, and an electrically insulating pipe is provided between these dissimilar metals. A superconducting coil device, characterized in that the conduit and the refrigerant pipe are connected via a dissimilar metal insulation joint that is airtightly inserted.