Insulation treatment method for helium inlet pipe of superconducting magnet

This application is a continuation of International Patent Application No. PCT/CN2019/105979, filed on Sep. 16, 2019, which claims the benefit of priority from Chinese Patent Application No. 201811593003.5, filed on Dec. 25, 2018. The content of the aforementioned applications, including any intervening amendments thereto, is incorporated herein by reference.

The present application relates to insulation treatment for a superconductor in a nuclear fusion device, and more particularly to an insulation treatment method for a helium inlet pipe of a superconducting magnet.

Thermonuclear fusion, as one of ultimate energy solutions, will provide humans with inexhaustible clean energy. In the international thermonuclear experimental reactor (ITER) under construction, a superconducting magnet, as one of the most crucial components, is generally exposed to a very harsh working environment such as complex mechanical and electromagnetic conditions and thermal stress loads, so there are relatively high requirements for the electrical insulation properties of the magnet. During the insulation treatment of the magnet, the insulation treatment for the irregular parts of the magnet plays a crucial role in affecting the insulation performance of the magnet. Among such parts, the helium inlet pipe of the superconducting magnet for cooling, due to the high irregularity in shape, is required to be designed into a special insulation structure before the vacuum pressure impregnation with insulating resin, ensuring the magnet to have satisfactory insulation properties after the vacuum pressure impregnation.

An object of this application is to provide an insulation treatment method for a helium inlet pipe of a superconducting magnet to ensure the superconducting magnet to have satisfactory insulation properties at the irregular parts after the vacuum pressure impregnation with a resin, which is of great engineering significance for the insulation treatment of a magnet with an irregular shape.

The technical solutions of this application are described as follows.

The application provides an insulation treatment method for a helium inlet pipe of a superconducting magnet, comprising:

welding an end of a metal conduit to an outer surface of a superconducting conductor;

wrapping an outer surface of the metal conduit with a composite insulating tape;

covering the outer surface of the superconducting conductor with fiberglass cloth;

filling spaces around a junction between the metal conduit and the superconducting conductor with G10, and fixing the G10 to the metal conduit and the superconducting conductor with a binding tape;

covering the G10 with a skirt-shaped insulating material with the metal conduit as a center; and

fixing the skirt-shaped insulating material to the metal conduit and the superconducting conductor with the binding tape;

wherein the binding tape is made of a composite insulating material.

In some embodiments, the composite insulating tape, the binding tape and the skirt-shaped insulating material are all made of a composite material of the fiberglass cloth and a polyimide film; and the G10 is a composite material composed of fiberglass and epoxy resin.

This application has the following beneficial effects.

In the application, the irregular parts of the magnet are filled with G10 to reduce the difficulty in the insulation treatment caused by the irregularity. Moreover, a skirt-shaped insulating material is provided around the metal conduit to alleviate the decrease in the insulation electrical performance caused by the defects in the insulation treatment due to the irregular shape.

FIG. 1 shows the structure designed in an insulation treatment method for a helium inlet pipe of a superconducting magnet according to the present application.

FIG. 2 shows the fitting of a skirt-shaped insulating material according to the present application.

In the drawings: 1 , metal conduit; 2 , superconducting conductor; 3 , fiberglass cloth; 4 , composite insulating tapes; 5 , G10; 6 , binding tapes; and 7 , skirt-shaped insulating material.

This application provided an insulation treatment method for a helium inlet pipe of a superconducting magnet, and a structure involved therein was shown in FIGS. 1 and 2 . The method was specifically implemented as follows.

1) A metal conduit 1 is welded to a superconducting conductor 2 .

2) Fiberglass cloth 3 is attached to a surface of the superconducting conductor 2 .

3) The metal conduit 1 is wrapped with a composite insulating tape 4 .

4) Spaces around a junction between the metal conduit 1 and the superconducting conductor 2 are filled with G10 5 .

5) The G10 5 is fixed by winding with a binding tape 6 .

6) The G10 5 around the metal conduit 1 is covered with a skirt-shaped insulating material 7 , which is fixed by winding with the binding tape 6 .

7) Step (6) is repeated to obtain the desired dielectric strength.

8) The part obtained in step (7) is subjected to insulation curing through vacuum pressure impregnation.

9) A dielectric withstand voltage test is performed on the part.

The composite insulating tape 4 , the binding tape 6 and the skirt-shaped insulating material 7 are all made of a composite material of the fiberglass cloth and a polyimide film; and the G10 is composed of fiberglass and epoxy resin.