JP7324166B2 - Current lead device, superconducting coil device, and maintenance method - Google Patents

Description

The present invention relates to a current lead device, a superconducting coil device, and a maintenance method.

The superconducting coil is connected to an external power supply by current leads. A superconducting coil and current leads are housed in the cryostat. Superconducting coils are cooled to cryogenic temperatures and used.

JP-A-7-131079

Cooling a superconducting coil to a cryogenic temperature takes a considerable amount of time, depending on its size. For example, a large superconducting coil such as that mounted on a superconducting cyclotron may require a period of about half a month to cool from room temperature to the target cryogenic temperature. If a current lead fails during operation of the superconducting coil, the operation of the superconducting coil is stopped, the cryogenic temperature is returned to room temperature, the failed current lead is replaced, and the superconducting coil is recooled. It is assumed that such a series of operations will require a long period of time, and the period will be downtime during which the superconducting coil cannot be operated.

One exemplary object of some aspects of the present invention is to facilitate the replacement of current leads.

According to an aspect of the present invention, a current lead device includes a current lead portion, a cylindrical case that houses the current lead portion, and an opening/closing structure that can expand and contract in an axial direction, and an opening/closing structure that is detachably attached. and a tubular case comprising a mounting member. A working space is formed between the mounting member and the opening structure when the opening structure is removed from the mounting member and axially contracted to allow access to the current leads from outside the tubular case.

According to one aspect of the present invention, a superconducting coil device includes a superconducting coil, a current lead connected to the superconducting coil, a cryostat that houses the superconducting coil, and a part of the cryostat that houses the current lead. The cylindrical case includes an opening/closing structure that can be expanded and contracted in an axial direction, and a mounting member to which the opening/closing structure is detachably attached. A working space is formed between the mounting member and the opening structure when the opening structure is removed from the mounting member and axially contracted to allow access to the current leads from outside the tubular case.

According to one aspect of the invention, a method for maintaining a current lead device is provided. A current lead device includes a current lead portion and a cylindrical case that accommodates the current lead portion. The maintenance method includes the steps of forming a work space that allows access to the current lead from outside the cylindrical case, and performing maintenance on the current lead through the work space. The cylindrical case includes an axially extendable opening/closing structure and an attachment member to which the opening/closing structure is detachably attached. A workspace is formed between the mounting member and the opening structure by removing the opening structure from the mounting member and axially contracting the structure.

It should be noted that arbitrary combinations of the above-described constituent elements and mutually replacing the constituent elements and expressions of the present invention in methods, devices, systems, etc. are also effective as embodiments of the present invention.

According to the present invention, it is possible to facilitate the replacement work of the current lead.

1 is a side view schematically showing a superconducting coil device according to an embodiment; FIG. 1 is a diagram schematically showing a current lead device according to an embodiment; FIG. It is a schematic diagram showing a maintenance method of the current lead device according to the embodiment. It is a schematic diagram showing a maintenance method of the current lead device according to the embodiment. It is a schematic diagram showing a maintenance method of the current lead device according to the embodiment. It is a schematic diagram showing a maintenance method of the current lead device according to the embodiment. 1 is a schematic perspective view showing a jig used in a maintenance method for a current lead device according to an embodiment; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the description and drawings, the same or equivalent constituent elements, members, and processes are denoted by the same reference numerals, and overlapping descriptions are omitted as appropriate. The scales and shapes of the illustrated parts are set for convenience in order to facilitate explanation, and should not be construed as limiting unless otherwise specified. The embodiment is an example and does not limit the scope of the present invention. All features and combinations thereof described in the embodiments are not necessarily essential to the invention.

FIG. 1 is a side view schematically showing a superconducting coil device 10 according to an embodiment. The superconducting coil device 10 includes a superconducting coil 12, and is mounted on a high magnetic field utilization equipment as a magnetic field source for an accelerator such as a cyclotron or other high magnetic field utilization equipment, and generates a high magnetic field required for the equipment. can be done.

The superconducting coil 12 is thermally coupled, for example, to a two-stage Gifford-McMahon (GM) refrigerator or other type of cryogenic refrigerator (not shown) to provide cryogenic temperatures below the superconducting transition temperature. used after being cooled to In this embodiment, the superconducting coil device 10 is configured as a so-called conduction cooling type in which the superconducting coil 12 is directly cooled by a cryogenic refrigerator instead of being immersed in a cryogenic liquid coolant such as liquid helium.

The superconducting coil device 10 includes a current lead portion 14 connected to the superconducting coil 12 , a cryostat 16 that accommodates the superconducting coil 12 , a cylindrical case 18 that accommodates the current lead portion 14 , and a power supply device 20 .

Current leads 14 are installed on superconducting coil 12 to connect superconducting coil 12 to power supply 20 . A pair of current lead portions 14 are provided at least on the positive electrode side and the negative electrode side. The tip of the current lead portion 14 is provided with a feedthrough portion 15 , that is, an airtight terminal for introducing current into the cryostat 16 . In the illustrated example, the current lead portion 14 is installed on the upper surface of the superconducting coil 12, but the arrangement is not limited to this. An exciting current is supplied from the power supply device 20 to the superconducting coil 12 through the current lead portion 14 . Thereby, the superconducting coil device 10 can generate a strong magnetic field.

The cryostat 16 is an insulated vacuum vessel that provides a cryogenic vacuum environment suitable for making the superconducting coil 12 superconducting. As an example, the superconducting coil 12 has an annular shape, and the cryostat 16 has a doughnut-like shape surrounding the superconducting coil 12 . A cylindrical case 18 extends from the body portion of the cryostat 16 that houses the superconducting coil 12 . In this example, two cylindrical cases 18 are installed on the upper surface of the cryostat 16 to respectively accommodate the pair of current lead portions 14 on the positive electrode side and the negative electrode side. Cryostat 16 and tubular case 18 are formed of a metallic material, such as stainless steel, or other suitable high-strength material to withstand ambient pressure (eg, atmospheric pressure).

A cylindrical case 18 forms part of the cryostat 16 and is designed as an external pressure vessel with a cylindrical shape. The tubular case 18 includes an axially expandable opening/closing structure such as a vacuum bellows 22 , a support flange 24 , and a connecting tubular portion 26 . Vacuum bellows 22 is, for example, a welded bellows, but may be any other type of bellows suitable for holding a vacuum. The support flange 24 is a vacuum flange attached to one end of the vacuum bellows 22 as a so-called cover of the cylindrical case 18 and supports the feedthrough portion 15 of the current lead portion 14 . The feedthrough portion 15 passes through the support flange 24 and is airtightly joined to the support flange 24 . The connecting tube portion 26 is attached to the other end of the vacuum bellows 22 and connects the vacuum bellows 22 to the body portion of the cryostat 16 . Unlike the vacuum bellows 22, the connecting tubular portion 26 has a fixed shape that does not expand or contract.

As will be described below, a working space 50 that allows access to the current leads 14 from outside the tubular case 18 forms between the support flange 24 and the vacuum bellows 22 when the vacuum bellows 22 is removed from the support flange 24 and axially retracted. It is formed between the bellows 22 (see FIG. 3).

FIG. 2 is a diagram schematically showing a current lead device according to an embodiment. An exemplary configuration of the current lead portion 14 and tubular case 18 shown in FIG. 1 will be further described with reference to FIG.

Current lead portion 14 forms a current path from feedthrough portion 15 to superconducting coil 12 . The current lead portion 14 comprises a metal current lead 28 connected to the feedthrough portion 15 and a superconducting current lead 30 connected to the metal current lead 28 . A superconducting current lead 30 is connected to the superconducting coil 12 .

More specifically, the feedthrough portion 15 and the metal current lead 28 are electrically connected at the first connection portion 32 . Also, the metal current lead 28 and the superconducting current lead 30 are electrically connected at the second connecting portion 34 . A superconducting current lead 30 is connected to a cold leaf spring 38 at a third connection 36 . The cold leaf springs 38 are connected to coil terminals 40 of the superconducting coil 12 . The metal current lead 28 and the low temperature leaf spring 38 are curved in a serpentine shape, and can absorb thermal contraction of the current lead portion 14 due to cryogenic cooling.

Superconducting current lead 30 may be formed of a cuprate superconductor or other high temperature superconducting material. Alternatively, the superconducting current lead 30 may be made of a low-temperature superconducting material typified by NbTi.

Struts 42 extending parallel to superconducting current leads 30 are provided to structurally support superconducting current leads 30 . The strut 42 is a pipe made of a metallic material such as stainless steel or other suitable high-strength material, and both ends of the strut 42 are fixed to the second connection 34 and the third connection 36, respectively.

The current paths other than the superconducting current lead 30 in the current lead portion 14, that is, the feedthrough portion 15, the metal current lead 28, the connection portions (32, 34, 36), and the low temperature leaf spring 38 are made of pure copper such as oxygen-free copper. It is made of a highly conductive metal material such as .

The first connection portion 32 is part of the feedthrough portion 15 and extends from the support flange 24 into the vacuum bellows 22 . The first connecting portion 32 is fastened to one end of the metal current lead 28 with a first bolt 44 . The second connection portion 34 is fastened to the other end of the metal current lead 28 with a second bolt 46 . The third connecting portion 36 is fastened with a low-temperature leaf spring 38 and a third bolt 48 . Each connecting portion (32, 34, 36) is formed in a block shape so as to enable fastening with a bolt.

A vacuum bellows 22 is removably attached to a support flange 24 . The vacuum bellows 22 has a telescopic portion 22a, and a first mounting flange 22b and a second mounting flange 22c respectively provided at both ends of the telescopic portion 22a. A first mounting flange 22 b is attached to the support flange 24 , and a second mounting flange 22 c is attached to a flange portion at one end of the connecting tube portion 26 . The other end of the connecting tube portion 26 is attached to the cryostat 16 .

Vacuum bellows 22 and connecting tube portion 26 extend axially along current lead portion 14 to accommodate current lead portion 14 therein. The vacuum bellows 22 and the connecting tube portion 26 are coaxially connected adjacent to each other. The vacuum bellows 22 accommodates a first connection portion 32, a metal current lead 28, and a second connection portion 34, and the connection tube portion 26 accommodates a superconducting current lead 30, a strut 42, and a third connection portion 36. is accommodated.

Further, a reinforcing member 49 arranged outside the cylindrical case 18 is provided so as to support the vacuum bellows 22 in the axial direction. The reinforcing member 49 is detachably attached to the tubular case 18 . The reinforcing member 49 is a rod-shaped member such as a long bolt. At one end of the stiffener 49 the support flange 24 and the first mounting flange 22b of the vacuum bellows 22 are fixed using corresponding nuts, and at the other end of the stiffener 49 the second mounting flange 22c of the vacuum bellows 22 and the connecting tube. 26 is fixed. The reinforcing member 49 extends axially along the stretchable portion 22a of the vacuum bellows 22, supports the stretchable portion 22a in the stretched state, and can retain its shape.

A radiation heat shield 17 surrounding the superconducting coil 12 is provided within the cryostat 16 in order to reduce radiant heat that may enter the superconducting coil 12 from the surrounding environment of the cryostat 16 . The radiation heat shield 17 also has a tubular shield 17a extending into the connecting tubular portion 26 of the tubular case 18, and the superconducting current lead 30 is arranged in the tubular shield 17a. The cylindrical shield 17a is fixed so as to be thermally coupled to the second connecting portion 34 while being electrically insulated.

Although not shown in FIG. 2, several insulating pipes are arranged in the cylindrical case 18 so as to surround the current lead portion 14, so that the current lead portion 14 is insulated from surrounding metal parts. . Such an insulating pipe is provided, for example, along the inner peripheral surface of the expandable portion 22a of the vacuum bellows 22. As shown in FIG. Another insulating pipe is provided along the inner and outer peripheral surfaces of the tubular shield 17a.

3 to 6 are schematic diagrams showing a maintenance method for the current lead device according to the embodiment. FIG. 7 is a schematic perspective view showing a jig used in the current lead device maintenance method according to the embodiment. This maintenance method is performed, for example, when a failure occurs in the current lead portion 14 . Therefore, the maintenance method includes a step of removing the current lead portion 14 and a step of attaching a new current lead portion 14 . Thereby, the current lead portion 14 is replaced.

First, the process of removing the current lead portion 14 will be described. The removal process starts from the initial state shown in FIG. The stiffener 49 is removed from the tubular case 18 . Since the stretchable portion 22a of the vacuum bellows 22 has a spring constant that can be manually pressed, the vacuum bellows 22 can be detached from the support flange 24 and contracted in the axial direction. Here, the length of contraction of the vacuum bellows 22 is slightly longer than the axial length of the first connecting portion 32 .

A working space 50 is then formed between the support flange 24 and the vacuum bellows 22, as shown in FIG. A worker can access the current lead portion 14 from outside the cylindrical case 18 through the work space 50 . More specifically, the work space 50 allows access to the first connection portion 32 between the feedthrough portion 15 and the metal current lead 28 from outside the tubular case 18 . Maintenance can be performed on the current lead portion 14 through the work space 50 .

A jig 52 may be used to hold the vacuum bellows 22 contracted. The jig 52 includes a pressing metal fitting 52a, a supporting metal fitting 52b, and a supporting member 52c. As shown in FIGS. 3 and 7, the presser fitting 52a is formed in an L shape, one surface of which is used to press the first mounting flange 22b of the vacuum bellows 22, and the other surface perpendicular to which is used for support. It is fixed with a bolt to the axially intermediate portion of the metal fitting 52b. A slit for receiving the support member 52c is formed in the surface of the presser fitting 52a that presses the first mounting flange 22b. The support fitting 52b is formed in a C shape or a rectangular shape with one side open, one end of which is fixed to the support flange 24, and the other end of which is fixed to the support member 52c. Both ends of the support metal fitting 52b are also formed with slits for receiving the support material 52c, similarly to the pressing metal fitting 52a. The support member 52c extends axially from the support flange 24, through the first mounting flange 22b to the second mounting flange 22c. The reinforcement member 49 described above may be used as the support member 52c. Thus, a work space 50 is formed between the support flange 24 and the clamp 52a.

As shown in FIG. 3 , an operator can access the first connection portion 32 through the work space 50 and remove the first bolt 44 from the first connection portion 32 . As a result, the fixation between the feedthrough portion 15 and the metal current lead 28 is released.

The vacuum bellows 22 is then returned to its extended state, as shown in FIG. For this purpose, the pressing metal fitting 52a is removed from the supporting metal fitting 52b, the telescopic portion 22a of the vacuum bellows 22 is extended in the axial direction, and the working space 50 is closed. The bolt connecting the second mounting flange 22c of the vacuum bellows 22 and the connecting tube portion 26 is removed.

Then, as shown in FIG. 5, the vacuum bellows 22 is removed from the connecting tube portion 26 . At this time, since the support flange 24 is attached to the vacuum bellows 22 by the jig 52, the support flange 24 is removed together with the vacuum bellows 22. Since the bolting of the first connection part 32 has already been released as described above, the feedthrough part 15 can also be removed from the metal current lead 28 together with the support flange 24 .

Additionally, the metal current lead 28 is removed from the second connection 34, as shown in FIG. The connecting tubular portion 26 is removed from the cryostat 16 , and the tubular shield 17 a is removed from the second connecting portion 34 and the radiant heat shield 17 . Finally, the assembly of superconducting current lead 30 , second connection 34 , third connection 36 , strut 42 and cold leaf spring 38 is removed from superconducting coil 12 . Thus, the current lead portion 14 and the cylindrical case 18 are disassembled.

The mounting process of the current lead portion 14 is performed by the reverse procedure of the removing process. A new current lead portion 14 is prepared, and the current lead portion 14 and the cylindrical case 18 can be reassembled by following the above procedure in reverse. That is, first, as shown in FIG. 6, an assembly including superconducting current leads 30 and cold leaf springs 38 is bolted to superconducting coil 12 . As shown in FIG. 5, the tubular shield 17a is attached to the second connecting portion 34 and the radiation heat shield 17 with bolts, respectively, and the connecting tubular portion 26 is attached to the cryostat 16 with bolts so as to surround them. A metal current lead 28 is attached to the second connection portion 34 with a second bolt 46 .

Next, as shown in FIG. 4, the assembly of support flange 24 and vacuum bellows 22 combined by jig 52 is bolted to connecting tube 26 . At this time, the feedthrough portion 15 and the metal current lead 28 are not yet fixed. As shown in FIG. 3, a working space 50 is formed between the support flange 24 and the vacuum bellows 22 by axially contracting the vacuum bellows 22 . The support flange 24 is pressed by the presser fitting 52a, and the vacuum bellows 22 is held in a contracted state.

An operator can access the first connecting portion 32 from outside the tubular case 18 through the working space 50 and fix the feedthrough portion 15 and the metal current lead 28 with the first bolts 44 . The jig 52 is then removed and the vacuum bellows 22 is returned to its extended state as shown in FIG. Further, a stiffener 49 is used to secure the support flange 24, the vacuum bellows 22 and the connecting tube 26 to each other. Thus, the assembly of the current lead portion 14 and the tubular case 18 is completed.

For comparison, consider the case where the entire cylindrical case 18 is a cylinder with a fixed shape. If the support flange 24 is arranged on the fixed cylinder together with the feedthrough portion 15 , the fixed cylinder is covered with the support flange 24 . Since the first connecting portion 32 between the feedthrough portion 15 and the metal current lead 28 is confined in the fixed cylinder, the first connecting portion 32 cannot be fastened.

There may be a design in which a window that can be opened and closed is provided on a part of the side surface of the fixed barrel, but in that case the fixed barrel is no longer axially symmetrical due to the existence of the window. Such a non-axisymmetric shape is not easy to design as an external pressure vessel. In particular, when miniaturization of the superconducting coil device 10 is intended, the diameter of the fixed cylinder is also reduced, which increases the difficulty in designing the installation of the window structure.

On the other hand, according to the embodiment, the work space 50 can be formed using an opening/closing structure that can be expanded and contracted in the axial direction like the vacuum bellows 22 . A worker can access the current lead portion 14 from outside the cylindrical case 18 through the work space 50 and perform desired maintenance such as replacement of the current lead portion 14 . Further, since the cylindrical case 18 including the vacuum bellows 22 has a cylindrical, axisymmetric structure, it can be easily designed as an external pressure vessel.

The present invention has been described above based on the examples. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and that various design changes and modifications are possible, and that such modifications are within the scope of the present invention. By the way. Various features described in relation to one embodiment are also applicable to other embodiments. A new embodiment resulting from combination has the effects of each of the combined embodiments.

Although the vacuum bellows 22 are removably attached to the support flange 24 in the above-described embodiment, the vacuum bellows 22 may be removably attached to other mounting members. For example, the vacuum bellows 22 is removably attached to the connecting tube portion 26 and the work space 50 allowing access to the current lead portion 14 from outside the tubular case 18 is provided when the vacuum bellows 22 is removed from the connecting tube portion 26 . It may be formed between the connecting tube portion 26 and the vacuum bellows 22 when contracted axially.

In the above-described embodiment, the vacuum bellows 22 is provided between and connects the support flange 24 and the connecting tube portion 26, but instead of this, a fixed tube is connected to the support flange 24, with which the fixed tube is connected. A cryostat 16 may be connected by a vacuum bellows 22 . In this case, the vacuum bellows 22 is removably attached to the fixed barrel, and the working space 50 that allows access to the current leads 14 from outside the tubular case 18 is axially removed from the fixed barrel. may be formed between the fixed barrel and the vacuum bellows 22 when contracted.

In the embodiment described above, the vacuum bellows 22 is provided axially as part of the cylindrical case 18 , but the vacuum bellows 22 may be provided along the entire length of the cylindrical case 18 in the axial direction. That is, support flange 24 may be connected to cryostat 16 by vacuum bellows 22 .

In the above-described embodiment, the current lead portion 14 on the positive electrode side and the current lead portion 14 on the negative electrode side are housed in separate cylindrical cases 18, but these two current lead portions 14 are housed in one cylindrical case. A configuration housed in 18 is also possible.

Although the present invention has been described using specific terms based on the embodiment, the embodiment only shows one aspect of the principle and application of the present invention, and the embodiment does not include the claims. Many variations and rearrangements are permissible without departing from the spirit of the invention as defined in its scope.

10 superconducting coil device 12 superconducting coil 14 current lead portion 15 feedthrough portion 16 cryostat 18 cylindrical case 22 vacuum bellows 28 metal current lead 32 first connection portion 49 reinforcement member 50 work space.

Claims (6)

a current lead;
a cylindrical case that houses the current lead portion, the cylindrical case including an opening/closing structure that can expand and contract in the axial direction, and a mounting member to which the opening/closing structure is detachably attached,
A work space permitting access to the current leads from outside the tubular case is defined between the mounting member and the opening/closing structure when the opening/closing structure is removed from the mounting member and axially contracted. A current lead device, characterized in that: 2. The current lead device of claim 1, wherein said opening and closing structure comprises a vacuum bellows. The current lead portion includes a feedthrough portion supported by the mounting member, and a metal current lead connected to the feedthrough portion, and the work space extends from the outside of the cylindrical case to the feedthrough portion. 3. A current lead device according to claim 1 or 2, characterized in that it allows access to a connection with the metal current lead. 4. The apparatus according to any one of claims 1 to 3, further comprising a reinforcing member disposed outside the cylindrical case and detachably attached to the cylindrical case so as to axially support the opening/closing structure. A current lead device according to any one of the preceding claims. a superconducting coil;
a current lead connected to the superconducting coil;
a cryostat housing the superconducting coil;
A cylindrical case that forms a part of the cryostat and houses the current lead part, the cylinder comprising an opening/closing structure that can expand and contract in the axial direction, and a mounting member to which the opening/closing structure is detachably attached. a shaped case, and
A work space permitting access to the current leads from outside the tubular case is defined between the mounting member and the opening/closing structure when the opening/closing structure is removed from the mounting member and axially contracted. A superconducting coil device comprising: A maintenance method for a current lead device, the current lead device comprising: a current lead portion; and a cylindrical case housing the current lead portion, the method comprising:
forming a work space that allows access to the current lead from outside the cylindrical case;
a step of performing maintenance on the current lead portion through the work space,
The cylindrical case includes an opening/closing structure that can be expanded and contracted in the axial direction, and a mounting member to which the opening/closing structure is detachably attached,
The maintenance method, wherein the work space is formed between the mounting member and the opening/closing structure by removing the opening/closing structure from the mounting member and axially contracting the structure.

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