Separable high-temperature superconducting current lead structure for liquid-helium-free superconducting magnet

Abstract

The utility model discloses a detachable high-temperature superconducting current lead structure for a liquid-helium-free superconducting magnet, and relates to the technical field of superconducting magnets. Comprising a 300K cover plate fixed at the position of a magnet tower head, a corrugated pipe is fixed at the top of the 300K cover plate, a cover plate is mounted at the top of the corrugated pipe, two lead columns are fixed on the cover plate through flange joints, and each lead column extends in the corrugated pipe, penetrates through the 300K cover plate and is in plugging fit with a lead welding base arranged below the 300K cover plate. The on-off state of the external circuit and the internal circuit is controlled; according to the utility model, the normal conducting section of the high-temperature lead is designed to be separable, the lead column is inserted during excitation, and the lead column is separated after magnet closed loop is completed after excitation, so that the conduction heat leakage of the current lead can be greatly reduced; and the lead column is always located in the cavity and does not exchange with the outside, so that the phenomenon that the vacuum degree of the vacuum container becomes poor due to the fact that the pluggable current lead is difficult to seal is avoided.

Description

Technical Field

[0001] This utility model relates to the field of superconducting magnet technology, specifically to a detachable high-temperature superconducting current lead structure for liquid helium-free superconducting magnets. Background Technology

[0002] Currently, in liquid helium-free superconducting magnets, a DC power supply is commonly used to excite the superconducting magnet, and current is introduced into the magnet's interior using current leads. Current leads are classified into fixed (non-removable) and detachable current leads based on their connection method. High-temperature superconducting current leads are a key technology in liquid helium-free magnets. Current leads mainly consist of a normal conducting section and a superconducting section, and the materials are primarily pure metals, alloys, and high-temperature tapes. In practical liquid helium-free superconducting magnet systems, the section from room temperature to 50K is the normal conducting section of the current leads, while the section from 50K to 4K is the high-temperature superconducting section.

[0003] In superconducting magnets, current leads are one of the main sources of heat leakage. Because these leads operate in the 300K to 4K temperature range, they carry heat from the hot end to the cold end. When current flows through the leads, they also generate Joule heating, some of which is conducted to the cold end, increasing heat loss. Removable current leads are used after magnetization is complete, removing them from the vacuum chamber. This "removal" of the thermal bridge reduces heat leakage. However, removable leads also have drawbacks. Separable connectors have poor reliability at low temperatures, requiring sufficient mechanical force to ensure good thermal contact. Contact resistance increases due to insertion and removal, leading to increased heat leakage and potentially limiting the magnet's operating current. Furthermore, insertion and removal require inserting electrodes that were not initially inserted, and removal is necessary after magnetization. Perfect sealing is difficult to achieve during the entire insertion and removal process, potentially introducing moisture and other impurities from the air into the vacuum chamber, reducing vacuum levels and increasing heat leakage. Therefore, we provide a detachable high-temperature superconducting current lead structure for liquid helium-free superconducting magnets. Utility Model Content

[0004] The purpose of this invention is to provide a detachable high-temperature superconducting current lead structure for liquid helium-free superconducting magnets.

[0005] The technical problem solved by this utility model is that in the prior art, pluggable current leads are difficult to guarantee the sealing during the plugging and unplugging process, which can easily lead to a decrease in the vacuum level of the vacuum chamber and an increase in heat leakage.

[0006] This utility model can be achieved through the following technical solution: a detachable high-temperature superconducting current lead structure for a liquid helium-free superconducting magnet, including a 300K cover plate fixed at the magnet tower head position, a corrugated pipe fixed on the top of the 300K cover plate, a cover plate installed on the top of the corrugated pipe, two lead posts fixed on the cover plate through flange joints, each lead post extending through the 300K cover plate inside the corrugated pipe and engaging with a lead welding base located below the 300K cover plate to control the on / off state of the external circuit and the internal circuit.

[0007] A further technical improvement of this utility model is that: the lead post includes a vacuum electrode and a lead plug coaxially fixed to its bottom; the top of the lead welding base is provided with two lead female heads, and each lead plug is plugged into and unplugged with the corresponding lead female head.

[0008] A further technical improvement of this utility model is that an insulating support cylinder is vertically fixed at the bottom of each lead wire welding base, and the lead wire welding base is fixed in the 50K space by the insulating support cylinder.

[0009] A further technical improvement of this utility model is that at least two screws are evenly arranged on the outer periphery of the corrugated pipe, the bottom of each screw is rotatably connected to the 300K cover plate, and the top of each screw is threadedly engaged with a fixing block evenly fixed on the edge of the cover plate.

[0010] A further technical improvement of this utility model is that the number and position of the fixing blocks correspond to the screw.

[0011] A further technical improvement of this utility model is that the on / off state of the excitation circuit corresponds to the compression / tension state of the bellows, and when the bellows is in the compressed state, the lead plug is inserted into the corresponding lead female head, and when the bellows is in the stretched state, the lead plug is pulled out of the corresponding lead female head.

[0012] A further technical improvement of this utility model is that the insertion and removal of the lead plug and the lead female are located in an independent 4K temperature zone, and the insertion and removal structure of the two is set with a certain taper.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] (1) The present invention designs the normally conducting section of the high temperature lead to be detachable. When energized, the lead post is inserted and after the magnet closed loop is completed, the lead post is detached. This can greatly reduce the heat leakage of the current lead. The lead post is always inside the cavity and does not exchange with the outside. This avoids the phenomenon that the vacuum degree of the vacuum container deteriorates due to the sealing difficulties of pluggable current leads.

[0015] (2) The insertion and extraction position is set in the non-traditional low temperature 4k temperature range between 50K and 300K temperature range to further reduce the primary heat leakage of the magnet;

[0016] (3) The contact part between the lead post and the lead female head adopts a small taper, radial positioning and tight fit to ensure sufficient contact area, thereby increasing the working current of the magnet and reducing the release of energy that is not conducive to timeout caused by insufficient contact area. Attached Figure Description

[0017] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0018] Figure 1 This is a schematic diagram of the overall external structure of this utility model;

[0019] Figure 2 This is a cross-sectional view of the internal connection state of this utility model.

[0020] In the diagram: 1. 300K cover plate; 2. Bellows; 3. Cover plate; 4. Flange joint; 5. Lead plug; 6. Vacuum electrode; 7. Lead welding base; 8. Lead female head; 9. Insulating support cylinder; 10. Screw; 11. Fixing block. Detailed Implementation

[0021] To further illustrate the technical means and effects adopted by this utility model in order to achieve the intended utility model purpose, the following detailed description of the specific implementation methods, structure, features and effects of this utility model is provided in conjunction with the accompanying drawings and preferred embodiments.

[0022] Please see Figure 1-2 As shown, a detachable high-temperature superconducting current lead structure for a liquid helium-free superconducting magnet includes a 300K cover plate 1 welded and fixed to the magnet tower head position. Two independent insulating support cylinders 9 are vertically arranged side by side at the bottom of the 300K cover plate 1, and the bottom of the insulating support cylinders 9 is fixed in the 50K temperature zone.

[0023] Each insulating support cylinder 9 has a lead wire welding base 7 fixed to its top, and a lead wire female head 8 is fixedly installed on the top of each lead wire welding base 7.

[0024] A bellows 2 is fixedly installed on the top of the 300K cover plate 1 in the vertical direction. A cover plate 3 is coaxially fixed on the top of the bellows 2. Two flange joints 4 are symmetrically sealed on the top of the cover plate 3. In this embodiment, KF40 flanges are selected according to the size requirements.

[0025] A vacuum electrode 6 is coaxially fixed to each flange joint 4. One end of the vacuum electrode 6 extends through the flange joint 4 into the bellows 2, and a lead plug 5 is coaxially fixed to the end of the bellows 2 by soldering. When energized, the bellows 2 is in a compressed state, and the end of the lead plug 5 away from the vacuum electrode 6 passes through the 300K cover plate 1 and is inserted into the corresponding lead female head 8. After energization, the bellows 2 is in a stretched state, and the end of the lead plug 5 away from the vacuum electrode 6 is pulled out from the corresponding lead female head 8, completing the power-off operation. It should be noted that the insertion and removal mating area between the lead plug 5 and the lead female head 8 is set to a low temperature zone of 4K, thereby reducing the first-stage heat leakage of the magnet.

[0026] Preferably, the top of the lead plug 5 has a pre-reserved wire groove, and the bottom end of the vacuum electrode 6 is inserted into the wire groove through a copper braided wire and fixed in the wire groove by soldering to ensure the stability of the connection; the plug-in and plug-out mating structure of the lead plug 5 and the lead female head 8 is set with a certain taper, which ensures radial positioning and sufficient contact area.

[0027] At least two screws 10 are evenly arranged on the outer periphery of the bellows 2. The bottom of each screw 10 is rotatably connected to the top of the 300K cover plate 1. The top edge of the cover plate 3 is evenly fixed with a fixing block 11 corresponding to the screw 10. The top of each screw 10 passes through the fixing block 11 and is threadedly connected to it. The end of the screw 10 that passes through the fixing block 11 is threadedly connected with a limit nut.

[0028] When excitation is required, the screw 10 is rotated to reduce the distance between the 300K cover plate 1 and the cover plate 3, the threaded tube 2 is compressed, and the lead plug 5 is inserted into the lead female head 8 to complete the circuit conduction. After excitation is completed, the screw 10 is rotated in the opposite direction to increase the distance between the 300K cover plate 1 and the cover plate 3, the threaded tube 2 is stretched, the lead plug 5 is pulled out from the lead female head 8, and the resistance between the two electrodes is measured. When the measurement result shows 0, it indicates that the vacuum electrode 6 is disconnected from the internal circuit. Then, the corresponding screw 10 is locked and fixed using a limit nut.

[0029] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Although the present utility model has been disclosed above with reference to a preferred embodiment, it is not intended to limit the present utility model. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present utility model. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present utility model without departing from the scope of the present utility model shall still fall within the scope of the present utility model.

Claims

1. A detachable high-temperature superconducting current lead structure for a liquid helium-free superconducting magnet, comprising a 300K cover plate (1) fixed at the magnet tower head, characterized in that, The 300K cover plate (1) is fixed with a corrugated pipe (2) on top, and a cover plate (3) is installed on the top of the corrugated pipe (2). Two lead wire posts are fixed on the cover plate (3) through a flange joint (4). Each lead wire post extends through the corrugated pipe (2) and penetrates the 300K cover plate (1) and is plugged into and engaged with the lead wire welding base (7) located below the 300K cover plate (1) to control the on / off state of the external circuit and the internal circuit.

2. The detachable high-temperature superconducting current lead structure for a liquid helium-free superconducting magnet according to claim 1, characterized in that, The lead post includes a vacuum electrode (6) and a lead plug (5) coaxially fixed to its bottom. The lead welding base (7) is provided with two lead female heads (8) on its top. Each lead plug (5) is plugged into and unplugged from the corresponding lead female head (8).

3. The detachable high-temperature superconducting current lead structure for a liquid helium-free superconducting magnet according to claim 1, characterized in that, Each of the lead wire welding bases (7) is vertically fixed to the bottom with an insulating support cylinder (9), and the lead wire welding bases (7) are fixed in the 50K space by the insulating support cylinder (9).

4. The detachable high-temperature superconducting current lead structure for a liquid helium-free superconducting magnet according to claim 1, characterized in that, At least two screws (10) are evenly arranged on the outer periphery of the corrugated pipe (2). The bottom of each screw (10) is rotatably connected to the 300K cover plate (1), and the top of each screw (10) is threadedly engaged with a fixing block (11) evenly fixed on the edge of the cover plate (3).

5. A detachable high-temperature superconducting current lead structure for a liquid helium-free superconducting magnet according to claim 4, characterized in that, The number and position of the fixing blocks (11) correspond to the screw (10).

6. The detachable high-temperature superconducting current lead structure for a liquid helium-free superconducting magnet according to claim 1, characterized in that, The on / off state of the excitation circuit corresponds to the compression / tension state of the bellows (2). When the bellows (2) is in the compression state, the lead plug (5) is inserted into the corresponding lead female head (8). When the bellows (2) is in the tension state, the lead plug (5) is pulled out of the corresponding lead female head (8).

7. A detachable high-temperature superconducting current lead structure for a liquid helium-free superconducting magnet according to claim 2, characterized in that, The insertion and removal of the lead plug (5) and the lead female (8) are located in an independent 4K temperature zone, and the insertion and removal structure of the two is set with a certain taper.

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