JPH0231510B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a superconducting device, and particularly to a superconducting device in which the structure of a thermal radiation shield installed between a superconducting coil and a vacuum vessel is improved.

[Background of the invention]

Superconducting coils used in nuclear fusion devices, etc. must be cooled to an extremely low temperature (4.2〓) in order to achieve superconductivity. Therefore, it is necessary to prevent heat from entering from the atmosphere. A thermal radiation shield is provided as a means to prevent this heat from entering.

This thermal radiation shield consists mainly of a copper shield plate that has a shape that covers the superconducting coil and has good thermal conductivity, and a tube through which a low-temperature fluid (for example, liquid nitrogen) flows is wound around the shield plate in a meandering manner and fixed to the shield plate.
On top of this, multiple layers of aluminum evaporated ultra-thin films are superimposed for heat reflection.

FIG. 2 shows a superconducting device equipped with the above-mentioned thermal radiation shield.

As shown in the figure, a vacuum container 1 that houses a superconducting coil (not shown) and performs vacuum insulation is formed in a cylindrical shape, and has flanges on the top and bottom so that it can be covered with a vacuum lid (not shown). It's getting old.
A substantially cylindrical copper shield plate 2 of a thermal radiation shield is provided along the wall surface of the vacuum container 1, and is held by a lifting tool 3 from the inner wall of the vacuum container 1. A refrigerant flow pipe 4 is wound around the copper shield plate 2 in a meandering manner and is fixed thereto. Furthermore, a multilayer heat insulating film 5 such as an extremely thin aluminum vapor-deposited film is bonded thereon. The inlet 6 of the refrigerant flow pipe 4 penetrates the wall of the vacuum container 1 and is drawn out to the outside.

In a superconducting device having such a thermal radiation shield, since the device is small, the copper shield plate 2 is formed into a cylindrical shape.
Although it is possible to have an integral structure in which the refrigerant flow pipe 4 is fixed to the refrigerant flow pipe 4, this conventional structure has the following drawbacks.

That is, since a copper shield plate 2 with good thermal conductivity is generally used, the necessary thickness of the copper shield plate 2 is constant regardless of whether it is large or small. Therefore, as the diameter of the copper shield plate 2 increases, its rigidity decreases, and for example, it is deformed by the heat generated when soldering or brazing the refrigerant flow pipe 4, making it difficult to manufacture and reducing its rigidity in handling. It becomes more difficult. In addition, when refrigerant is passed through the refrigerant flow pipe 4 after installation, the diameter becomes large even if the amount of heat shrinkage per unit length is constant, so the internal stress generated within the copper shield plate 2 becomes excessive, and in severe cases It becomes deformed.

[Purpose of the invention]

The present invention has been made in view of the above points, and its purpose is to prevent a decrease in rigidity and thermal deformation without impairing the effect of preventing heat intrusion even if the diameter of the thermal radiation shield becomes large. It is an object of the present invention to provide a superconducting device that can reduce internal stress and is easy to manufacture.

[Summary of the invention]

The present invention provides a divided shield plate obtained by dividing a shield plate in the circumferential direction, a divided refrigerant flow pipe meanderingly fixed to the divided shield plate for each divided shield plate, and a divided multilayer insulation film covering each divided shield plate. The desired purpose was achieved by configuring a plurality of divided heat radiation shields from the above, and by overlapping each divided end of the adjacent divided shield plates to form a substantially cylindrical heat radiation shield. It is something.

[Embodiments of the invention]

The present invention will be described below based on embodiments shown in the drawings. Incidentally, the same reference numerals are used for the same parts as in the past.

FIG. 1 shows an embodiment of the invention. As shown in the figure, the vacuum container 1 has the same structure as the conventional one, and the thermal radiation shield is held on the inner wall of the vacuum container 1 by a hanging fitting (not shown) as in the conventional one. The thermal radiation shield of this embodiment is also composed of a copper shield plate, a refrigerant flow pipe, and a multilayer insulation film. Divided copper shield plate 7
The divided refrigerant distribution pipes 8 meander at predetermined intervals and are fixed by soldering or the like, and the divided refrigerant distribution pipes 8
A plurality of divided thermal radiation shields are constituted by a divided multilayer thermal insulation film 10 formed by laminating a multilayer aluminum vapor-deposited thin film or the like on each divided copper shield plate 7 on the side to which the divided copper shield plates 7 are fixed, and the adjacent divided thermal radiation shields are By overlapping each divided end portion of the divided copper shield plate 7, a substantially cylindrical thermal radiation shield is assembled. Note that each divided refrigerant flow pipe 8 penetrates the wall of the vacuum vessel 1 and has an inlet 9 at its end, and the inlets 9 are connected to each other outside the vacuum vessel 1.

According to this embodiment, a substantially cylindrical copper shield plate is divided into a plurality of pieces in the circumferential direction to form divided copper shield plates 7 having a small width in the circumferential direction. Even if the size increases, it will prevent a decrease in rigidity and thermal deformation when fixing refrigerant flow pipes by soldering, etc., without impairing the effect of preventing heat intrusion. In addition to eliminating this difficulty, it is also possible to significantly reduce internal stress due to thermal contraction during cooling. Moreover, since the refrigerant flow tubes are also divided for each divided copper shield plate 7 to form divided refrigerant flow tubes 8 with short flow paths, each divided copper shield plate 7 can be cooled uniformly and efficiently. Moreover, since the thermal radiation shield can be constructed by simply assembling each of the divided thermal radiation shields, it is extremely easy to manufacture.

Note that the material of the shield plate may be any material as long as it has good thermal conductivity; for example, aluminum may be used.

〔Effect of the invention〕

According to the superconducting device of the present invention described above, the substantially cylindrical shield plate is divided into a plurality of pieces in the circumferential direction to form a divided shield plate with a small width in the circumferential direction. Even if the temperature increases, it prevents a decrease in rigidity and thermal deformation when fixing refrigerant flow pipes by soldering, etc., without impairing the effect of preventing heat intrusion. In addition to eliminating this difficulty, it is also possible to significantly reduce internal stress due to thermal contraction during cooling. Moreover, since the refrigerant flow tubes are also divided for each divided shield plate to form divided refrigerant flow tubes with short flow paths, each divided shield plate can be cooled uniformly and efficiently. Moreover, since the thermal radiation shield can be constructed by simply assembling each of the divided thermal radiation shields, it is extremely easy to manufacture.

[Brief explanation of drawings]

FIG. 1 is a partial perspective view of a cryogenic container employed in the present invention, and FIG. 2 is a partial perspective view of a conventional cryogenic container. 1... Vacuum container, 7... Divided copper shield plate,
8...Divided refrigerant flow pipe, 10...Divided multilayer heat insulating membrane.

Claims (1)

[Claims] 1. A superconducting coil, a substantially cylindrical vacuum container housing the superconducting coil, and a substantially cylindrical heat sink installed between the inner wall of the vacuum container and the superconducting coil to prevent heat from entering the superconducting coil. The thermal radiation shield includes a substantially cylindrical shield plate with good thermal conductivity, a refrigerant flow pipe that is wound and fixed to the shield plate in a meandering manner and allows the cryogenic refrigerant to flow through it, and In a superconducting device comprising a multilayer heat-insulating film that covers the shield plate on the side to which the flow pipe is fixed and performs heat reflection, a divided shield plate that divides the shield plate into a plurality of parts in the circumferential direction, and each divided shield plate A plurality of divided heat radiation shields are constructed from divided refrigerant flow pipes meanderingly fixed to each divided refrigerant flow pipe and divided multilayer insulation films that cover each divided shield plate, and each division of adjacent divided shield plates A superconducting device characterized by overlapping ends.