A method for applying preload to a heat-treated Nb3Sn superconducting magnet coil

Abstract

This invention discloses a method for applying preload to a heat-treated Nb3Sn superconducting magnet coil, comprising the following steps: S1: Selecting an Nb3Sn coil and winding it tightly onto a magnet frame, with glass fiber cloth tightly wrapped around the outside of the Nb3Sn coil; S2: Winding a stainless steel preload coil around the outside of the glass fiber cloth, and subjecting both the wound Nb3Sn coil and the stainless steel preload coil to heat treatment. After high-temperature heat treatment, vacuum epoxy impregnation is performed on both the Nb3Sn coil and the stainless steel preload coil using CTD epoxy resin; S3: Applying Stycast epoxy resin evenly to the outside of the impregnated stainless steel preload coil, and then uniformly winding an aluminum alloy preload coil. This invention, while ensuring the performance of the heat-treated Nb3Sn coil, increases the preload of the Nb3Sn coil, ensuring the overall rigidity of the coil, solving the problem of preload release after heat treatment of the Nb3Sn coil, and improving the stability of the coil.

Description

Technical Field

[0001] This invention relates to a loading method, and more particularly to a preload loading method for a heat-treated Nb3Sn superconducting magnet coil, belonging to the field of superconducting magnet coil technology. Background Technology

[0002] Nb3Sn compounds require heat treatment at 620-750℃ to form the A15 superconducting phase. The heat-treated Nb3Sn superconducting wire has poor mechanical properties, and its critical performance is highly sensitive to stress and strain. Moreover, most of the coil preload is released after heat treatment, and it cannot effectively constrain the superconducting magnet coil during the coil excitation process. Therefore, it is necessary to use an appropriate method to apply additional preload to the heat-treated superconducting coil to enhance the overall rigidity of the Nb3Sn superconducting magnet coil and improve its stability. This method can be used to develop high-field Nb3Sn superconducting magnet coils with stable performance.

[0003] This design proposes a method for applying preload to Nb3Sn superconducting magnet coils after heat treatment. Winding a stainless steel preload coil before heat treatment not only helps maintain the tightness of the Nb3Sn superconducting magnet coil but also protects it after heat treatment. Vacuum epoxy impregnation of the heat-treated Nb3Sn superconducting magnet coil and the stainless steel preload coil enhances the inter-turn and inter-layer insulation of the Nb3Sn superconducting magnet coil, further increasing the overall rigidity of the coil. Stycast epoxy resin is uniformly applied to the outer surface of the stainless steel preload coil, and then an aluminum alloy preload coil is uniformly wound under a certain tension to ensure the overall rigidity of the coil and constrain the expansion effect during the excitation process of the Nb3Sn superconducting magnet coil. Finally, Stycast-coated fiberglass tape is used to fix the aluminum alloy preload coil to prevent it from loosening under stress. This method is superior to applying preload to the Nb3Sn before heat treatment. The traditional method of applying preload to superconducting magnet coils compensates for the preload released by heat treatment without damaging the performance of Nb3Sn superconducting magnet coils, thereby improving the overall rigidity and stability of Nb3Sn superconducting magnet coils and providing key technologies for the development and application of Nb3Sn high-field superconducting magnet coils. Summary of the Invention

[0004] The purpose of this invention is to provide a method for applying preload to a heat-treated Nb3Sn superconducting magnet coil, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for applying preload to a heat-treated Nb3Sn superconducting magnet coil, comprising the following steps:

[0006] S1: Select an Nb3Sn coil and wind it onto the magnet frame using a close-wound method. Fiberglass cloth is tightly wrapped around the outside of the Nb3Sn coil.

[0007] S2: The stainless steel pre-tightening coil is wound on the outside of the glass fiber cloth. The wound Nb3Sn coil and the stainless steel pre-tightening coil are heat-treated together. After the high temperature heat treatment is completed, the Nb3Sn coil and the stainless steel pre-tightening coil are vacuum epoxy impregnated with CTD epoxy resin.

[0008] S3: After the stainless steel pre-tightening coil has been impregnated, Stycast epoxy resin is evenly applied to the outside of the coil, and the aluminum alloy pre-tightening coil is evenly wound. Finally, glass fiber braided tape coated with Stycast epoxy resin is tied to the outside of the aluminum alloy pre-tightening coil to reinforce the Nb3Sn superconducting magnet coil as a whole.

[0009] As a preferred embodiment of the present invention, the heat treatment temperature of the Nb3Sn coil is 620-750℃.

[0010] As a preferred embodiment of the present invention, in step S3, the structure of the Nb3Sn superconducting magnet coil includes a magnet skeleton, an Nb3Sn superconducting coil, glass fiber cloth, a stainless steel pre-tensioning coil, an aluminum alloy pre-tensioning coil, and a glass fiber tape. The Nb3Sn superconducting coil is wound around the outside of the magnet skeleton, the glass fiber cloth is wound around the outside of the Nb3Sn superconducting coil, the stainless steel pre-tensioning coil is wound around the outside of the glass fiber cloth, the aluminum alloy pre-tensioning coil is wound around the outside of the stainless steel pre-tensioning coil, and the glass fiber tape is wound around the outside of the aluminum alloy pre-tensioning coil. The Nb3Sn superconducting coil, the stainless steel pre-tensioning coil, and the aluminum alloy pre-tensioning coil are coaxially and concentrically nested from the inside out.

[0011] Compared with the prior art, the beneficial effects of the present invention are:

[0012] 1. This invention discloses a method for applying preload to a heat-treated Nb3Sn superconducting magnet coil. Before heat treatment, a stainless steel preload coil is wound, which not only helps maintain the tightness of the Nb3Sn superconducting magnet coil but also protects it after heat treatment. Vacuum epoxy impregnation of the heat-treated Nb3Sn superconducting magnet coil and the stainless steel preload coil is performed using CTD epoxy resin to enhance the inter-turn and inter-layer insulation of the Nb3Sn superconducting magnet coil, while further enhancing the overall rigidity of the coil. Stycast epoxy resin is uniformly applied to the outer surface of the stainless steel preload coil, and then a certain tension is applied... A pre-tightened aluminum alloy coil is wound with uniform force to ensure the overall rigidity of the coil and to constrain the expansion effect during the excitation process of the Nb3Sn superconducting magnet coil. Finally, the aluminum alloy pre-tightened coil is fixed with Stycast coated glass ribbon to prevent it from loosening under stress. Compared with the traditional method of applying pre-tightening force to the Nb3Sn superconducting magnet coil before heat treatment, this method compensates for the pre-tightening force released by heat treatment without damaging the performance of the Nb3Sn superconducting magnet coil, thereby improving the overall rigidity and stability of the Nb3Sn superconducting magnet coil. This provides a key technology for the development and application of Nb3Sn high-field superconducting magnet coils. Attached Figure Description

[0013] Figure 1 This is a cross-sectional schematic diagram of the b3Sn superconducting magnet coil of the present invention.

[0014] In the diagram: 1. Magnet frame; 2. Nb3Sn superconducting coil; 3. Glass fiber cloth; 4. Stainless steel pre-tightening coil; 5. Aluminum alloy pre-tightening coil; 6. Glass fiber tape. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] Please see Figure 1 This invention provides a technical solution for a preload loading method for heat-treated Nb3Sn superconducting magnet coils:

[0017] according to Figure 1 As shown, it includes the following steps:

[0018] S1: Select an Nb3Sn coil and wind it onto the magnet frame using a close-wound method. Fiberglass cloth is tightly wrapped around the outside of the Nb3Sn coil.

[0019] S2: The stainless steel pre-tightening coil is wound on the outside of the glass fiber cloth. The wound Nb3Sn coil and the stainless steel pre-tightening coil are heat-treated together. After the high temperature heat treatment is completed, the Nb3Sn coil and the stainless steel pre-tightening coil are vacuum epoxy impregnated with CTD epoxy resin.

[0020] S3: After the stainless steel pre-tightening coil has been impregnated, Stycast epoxy resin is evenly applied to the outside of the coil, and the aluminum alloy pre-tightening coil is evenly wound. Finally, glass fiber braided tape coated with Stycast epoxy resin is tied to the outside of the aluminum alloy pre-tightening coil to reinforce the Nb3Sn superconducting magnet coil as a whole.

[0021] Example 1: The structure of the Nb3Sn superconducting magnet coil includes a magnet frame 1, an Nb3Sn superconducting coil 2, a glass fiber cloth 3, a stainless steel pre-tensioned coil 4, an aluminum alloy pre-tensioned coil 5, and a glass fiber tape 6. The Nb3Sn superconducting coil 2 is wound around the outside of the magnet frame 1, the glass fiber cloth 3 is wound around the outside of the Nb3Sn superconducting coil 2, the stainless steel pre-tensioned coil 4 is wound around the outside of the glass fiber cloth 3, the aluminum alloy pre-tensioned coil 5 is wound around the outside of the stainless steel pre-tensioned coil 4, and the glass fiber tape 6 is wound around the outside of the aluminum alloy pre-tensioned coil 5. The Nb3Sn superconducting coil 2, the stainless steel pre-tensioned coil 4, and the aluminum alloy pre-tensioned coil 5 are coaxially and concentrically nested from the inside out.

[0022] This invention winds a stainless steel pre-tightened coil before heat treatment, which not only helps maintain the tightness of the Nb3Sn superconducting magnet coil, but also protects the Nb3Sn superconducting magnet coil after heat treatment; using CTD Vacuum epoxy impregnation of heat-treated Nb3Sn superconducting magnet coils and stainless steel pre-tightening coils enhances the inter-turn and inter-layer insulation of the Nb3Sn superconducting magnet coils, while further increasing the overall rigidity of the coil. Stycast epoxy resin is uniformly applied to the outer surface of the stainless steel pre-tightening coil, and then an aluminum alloy pre-tightening coil is wound uniformly under a certain tension to ensure the overall rigidity of the coil and constrain the expansion effect during the excitation process of the Nb3Sn superconducting magnet coil. Finally, Stycast-coated glass fiber tape is used to fix the aluminum alloy pre-tightening coil to prevent it from loosening under stress. Compared with the traditional method of applying pre-tightening force to the Nb3Sn superconducting magnet coil before heat treatment, this method compensates for the pre-tightening force released during heat treatment without damaging the performance of the Nb3Sn superconducting magnet coil, improving the overall rigidity and stability of the Nb3Sn superconducting magnet coil. This provides a key technology for the development and application of Nb3Sn high-field superconducting magnet coils.

[0023] In the description of this invention, it should be understood that the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0024] In this invention, unless otherwise explicitly specified and limited, for example, it can be a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two elements or an interaction between two elements. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0025] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for applying preload to a heat-treated Nb3Sn superconducting magnet coil, characterized in that, Includes the following steps: S1: Select an Nb3Sn coil and wind it onto the magnet frame using a close-wound method. Fiberglass cloth is tightly wrapped around the outside of the Nb3Sn coil. S2: The stainless steel pre-tightening coil is wound on the outside of the glass fiber cloth. The wound Nb3Sn coil and the stainless steel pre-tightening coil are heat-treated together. After the high temperature heat treatment is completed, the Nb3Sn coil and the stainless steel pre-tightening coil are vacuum epoxy impregnated with CTD epoxy resin. S3: After the stainless steel pre-tightening coil is impregnated, Stycast epoxy resin is evenly applied to the outside of the coil, and aluminum alloy pre-tightening coil is evenly wound. Finally, glass fiber braided tape coated with Stycast epoxy resin is tied to the outside of the aluminum alloy pre-tightening coil to reinforce the Nb3Sn superconducting magnet coil as a whole. In step S3, the structure of the Nb3Sn superconducting magnet coil includes a magnet frame (1), an Nb3Sn superconducting coil (2), a glass fiber cloth (3), a stainless steel pre-tightening coil (4), an aluminum alloy pre-tightening coil (5), and a glass fiber tape (6). The Nb3Sn superconducting coil (2) is wound around the outside of the magnet frame (1), the glass fiber cloth (3) is wound around the outside of the Nb3Sn superconducting coil (2), the stainless steel pre-tightening coil (4) is wound around the outside of the glass fiber cloth (3), the aluminum alloy pre-tightening coil (5) is wound around the outside of the stainless steel pre-tightening coil (4), and the glass fiber tape (6) is wound around the outside of the aluminum alloy pre-tightening coil (5). The Nb3Sn superconducting coil (2), the stainless steel pre-tightening coil (4), and the aluminum alloy pre-tightening coil (5) are coaxially and concentrically nested from the inside to the outside.

2. The method for applying preload to a heat-treated Nb3Sn superconducting magnet coil according to claim 1, characterized in that: The heat treatment temperature of the Nb3Sn coil is 620-750℃.

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