An integrally formed superconducting cavity for improving refrigeration efficiency and a preparation method and application thereof

Abstract

The application provides an integrally-formed superconducting cavity for improving refrigeration efficiency and a preparation method and application thereof. The integrally-formed superconducting cavity comprises a superconducting cavity body and a liquid helium pipeline wound on the outer surface of the superconducting cavity body; the superconducting cavity body comprises at least one hollow cavity, and beam tubes are fixedly arranged at two ends of the hollow cavity, respectively. The application integrally forms and winds the liquid helium pipeline on the outer surface of the superconducting cavity body by using an additive manufacturing method, so that the superconducting cavity can maintain an extremely low temperature of 2K under the premise of a small amount of liquid helium in use, and the use cost can be greatly reduced; and the structure is simple, the processing technology is simple, and the application is suitable for industrial application.

Description

Technical Field

[0001] This invention belongs to the field of accelerators and relates to a superconducting cavity, specifically to a one-piece molded superconducting cavity for improving cooling efficiency, its preparation method, and its application. Background Technology

[0002] Superconducting accelerators are the preferred choice for research and application in the current accelerator field. They are crucial components in major scientific projects such as linear colliders, advanced radiation sources, free-electron lasers, and spallation neutron sources. The superconducting cavity, located in a cryostat, is the core device of the superconducting accelerator, used to accelerate charged particle beams. During stable operation of the superconducting cavity, local surface and crystal defects generate a large amount of heat under high-intensity electromagnetic fields. If this heat cannot be transferred to the liquid helium in the cooling system in time, the temperature at the defect location will rise, causing a local superconducting state to transition to a non-superconducting state. The surrounding non-superconducting cavity walls will then generate a large amount of heat under high-intensity electromagnetic fields, creating a vicious cycle that eventually causes the entire superconducting cavity to instantly transition from a superconducting to a non-superconducting state. This loss of superconductivity not only leads to the massive evaporation of liquid helium, the cryogenic mass, but also causes the overall failure of the large scientific facility, resulting in huge economic losses. Therefore, it is essential to improve the cooling efficiency of the superconducting cavity during operation.

[0003] Under actual service conditions, only tens of micrometers of the inner surface of the superconducting cavity are in working condition, and the closer the cooling position is to the working surface, the higher the cooling efficiency. CN 103179775A discloses a superconducting accelerator, a superconducting cavity for the superconducting accelerator, and a method for its fabrication. This patent integrates a heat dissipation structure on the outer surface of the superconducting cavity by processing grooves or drilling holes, which is complex in terms of processing technology and has low cooling efficiency.

[0004] Currently, the superconducting cavities in large scientific facilities are all niobium superconducting cavities, manufactured using high-purity niobium plates as raw materials through stamping, welding, and post-processing. This manufacturing process is not only complex but also prone to introducing surface defects. In practical applications, the superconducting cavity is located in a cryogenic chamber maintained at an extremely low temperature of 2K. Existing dilution refrigerators are insufficient to achieve stable 2K cooling, necessitating immersion in large quantities of liquid helium for cooling. Liquid helium is a scarce resource, its price is expensive and continuously rising, resulting in extremely high operating costs.

[0005] Therefore, simplifying the fabrication process of superconducting cavities and improving the efficiency of liquid helium utilization are key to further promoting the application of large scientific facilities and reducing their operating costs. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a one-piece superconducting cavity for improving cooling efficiency, its fabrication method, and its application. This invention improves the efficiency of liquid helium utilization during use by integrating the liquid helium conduit and the superconducting cavity body into a single unit. Furthermore, the fabrication method is simple and suitable for industrial applications.

[0007] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides an integrally formed superconducting cavity for improving cooling efficiency, the integrally formed superconducting cavity comprising a superconducting cavity body and a liquid helium pipe wound around the outer surface of the superconducting cavity body; The superconducting cavity body includes at least one hollow cavity, and bundle tubes are fixedly disposed at both ends of the hollow cavity.

[0008] The present invention integrates a liquid helium pipe integrally formed and wound on the outer surface of the superconducting cavity body, so that the superconducting cavity can maintain an extremely low temperature of 2K with a small amount of liquid helium used during use.

[0009] As a preferred embodiment of the present invention, the hollow cavity is an ellipsoidal cavity.

[0010] Preferably, the major diameter of the hollow cavity is 75~410mm, for example, it can be 75mm, 100mm, 200mm, 300mm or 410mm, etc., but is not limited to the listed values, and other values ​​not listed within the range are also applicable; the minor diameter is 40~410mm, for example, it can be 40mm, 80mm, 120mm, 160mm, 220mm, 280mm, 340mm or 410mm, etc., but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0011] Preferably, the inner diameter of the bundle tube is 30~156mm, for example, it can be 30mm, 50mm, 70mm, 100mm, 120mm, 140mm or 156mm, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0012] Preferably, a superconducting cavity interface flange is provided at the end of the bundle tube away from the hollow cavity.

[0013] Preferably, the distribution density of liquid helium pipes on the outer surface of the hollow cavity is higher than that on the outer surface of the bundle tube.

[0014] It is worth noting that, along the axial symmetry direction, the hollow cavity has a drum-shaped (ellipsoidal) rotary hollow structure, and a liquid helium pipe is fixedly installed at a circumferential position perpendicular to the axial direction of the hollow cavity. Furthermore, the present invention can shorten the cooling distance and reduce the amount of liquid helium required for cooling by non-uniformly winding liquid helium pipes on the surface of the superconducting cavity body.

[0015] As a preferred embodiment of the present invention, the inner diameter of the liquid helium pipe is 1 to 6 mm, for example, it can be 1 mm, 2 mm, 3 mm, 4 mm, 5 mm or 6 mm, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0016] The inner diameter of the liquid helium pipe described in this invention is 1~6mm. If the inner diameter is too small, the liquid helium flow rate will be too low and it will not be able to achieve a sufficient cooling effect. If the inner diameter is too large, the liquid helium pipe will be too close to the working inner surface of the superconducting cavity, which will damage the support structure while interfering with the acceleration of particles.

[0017] Preferably, the liquid helium pipeline has a three-dimensional spiral or parallel channel cooling flow path.

[0018] Preferably, the inlet and outlet of the liquid helium pipeline are each independently equipped with a liquid helium interface flange.

[0019] Preferably, the working distance between the inner surface of the liquid helium pipe and the inner surface of the superconducting cavity body is 0.8~1.5mm, for example, it can be 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm or 1.5mm, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] It is worth noting that by controlling the working distance between the inner surface of the helium pipe and the inner surface of the superconducting cavity, the present invention can quickly remove the heat from the superconducting cavity, thereby reducing the amount of liquid helium used while maintaining the superconducting state.

[0021] In a second aspect, the present invention provides an additive manufacturing method for an integrally formed superconducting cavity for improving cooling efficiency as described in the first aspect, the additive manufacturing method comprising: (1) Establish a three-dimensional model of the integral superconducting cavity, slice and layer the three-dimensional model, and convert it into STL format data and import it into the operating system of the 3D printing equipment; (2) Spread niobium powder evenly on the substrate of the molding working cavity of the 3D printing equipment and set the molding parameters; (3) The integral superconducting cavity is obtained by repeatedly printing with an energy beam in the molding chamber; The printing includes laser printing or electron beam melting printing. Traditional superconducting cavities are fabricated using a combination of stamping and welding. While grooves can be machined on the outer surface of the superconducting cavity before welding flow channels, the manufacturing process is complex. Furthermore, external welding introduces gaps in the weld seams, hindering heat transfer. Additionally, the close proximity of the welding point to the inner surface makes the inner surface of the superconducting cavity susceptible to damage during welding. This invention utilizes additive manufacturing to integrally form the superconducting cavity, avoiding gaps and weld seams. This improves heat transfer efficiency while reducing the risk of damage to the working surface of the superconducting cavity.

[0022] As a preferred technical solution of the present invention, the particle size range of the niobium powder in step (2) is 10~150μm, for example, it can be 10μm, 30μm, 60μm, 90μm, 120μm or 150μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0023] Preferably, the sphericity of the niobium powder is ≥90%, for example, it can be 90%, 91%, 92%, 93%, 94% or 95%, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0024] Preferably, the oxygen content of the niobium powder is ≤100ppm, for example, it can be 100ppm, 90ppm, 80ppm, 70ppm, 60ppm or 50ppm, etc., but is not limited to the listed values, and other values ​​not listed within the value range are also applicable; the nitrogen content is ≤100ppm, for example, it can be 100ppm, 90ppm, 80ppm, 70ppm or 60ppm, etc., but is not limited to the listed values, and other values ​​not listed within the value range are also applicable.

[0025] In this invention, if the particle size of the niobium powder used in the additive manufacturing process is too large, it will result in poor powder flowability, which is not conducive to sintering; if the impurity content of the niobium powder is too high, it will result in a decrease in superconducting performance.

[0026] As a preferred technical solution of the present invention, the molding parameters in step (2) include energy beam power, energy beam scanning spacing, energy beam scanning speed, single-layer powder thickness and substrate preheating temperature.

[0027] As a preferred embodiment of the present invention, the laser printing is performed in an inert gas environment.

[0028] Preferably, the inert gas includes any one or a combination of at least two of argon, nitrogen, or helium. Typical but non-limiting combinations include: a combination of argon and nitrogen, a combination of argon and helium, a combination of nitrogen and helium, or a combination of nitrogen, helium, and argon.

[0029] Preferably, the power of the laser used for laser printing is 300~500W, for example, it can be 300W, 350W, 400W, 450W or 500W, but is not limited to the listed values. Other values ​​not listed within the value range are also applicable.

[0030] Preferably, the laser scanning speed of the laser printing is 500~800mm / s, for example, it can be 500mm / s, 550mm / s, 600mm / s, 650mm / s, 700mm / s, 750mm / s or 800mm / s, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0031] Preferably, the laser scanning spacing of the laser printing is 0.01~0.03mm, for example, it can be 0.01mm, 0.02mm or 0.03mm, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0032] Preferably, the thickness of a single layer of powder in the laser printing is 20~40μm, for example, it can be 20μm, 24μm, 28μm, 32μm, 36μm or 40μm, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0033] Preferably, the substrate preheating temperature in the laser printing is 400~600℃, for example, it can be 400℃, 450℃, 500℃, 550℃ or 600℃, etc., but is not limited to the listed values. Other values ​​not listed within the range are also applicable.

[0034] As a preferred embodiment of the present invention, the electron beam melting printing is performed in a vacuum environment.

[0035] Preferably, the vacuum degree inside the forming chamber during electron beam melting printing is ≤2×10⁻⁶. -2 Pa, for example, could be 2 × 10 -2 Pa, 1.9 × 10 -2 Pa, 1.8 × 10 -2 Pa, 1.7 × 10 -2 Pa, 1.6 × 10 -2 Pa or 1.5 × 10 -2 Pa, etc., but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0036] Preferably, the power of the electron beam used in the electron beam melting printing is 300~3000W, for example, it can be 300W, 500W, 1000W, 2000W or 3000W, but is not limited to the listed values. Other values ​​not listed within the value range are also applicable.

[0037] Preferably, the electron beam scanning spacing of the electron beam melting printing is 0.03~0.08mm, for example, it can be 0.03mm, 0.04mm, 0.05mm, 0.06mm, 0.07mm or 0.08mm, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0038] Preferably, the thickness of a single layer of powder in the electron beam melting printing is 20~100μm, for example, it can be 20μm, 40μm, 60μm, 80μm or 100μm, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0039] Preferably, the substrate preheating temperature in the electron beam melting printing is 400~1300℃, for example, it can be 400℃, 600℃, 800℃, 1000℃ or 1300℃, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0040] In this invention, during the additive manufacturing process, a low scanning speed will result in the powder not fusing, while a high scanning speed will result in molten pool splashing.

[0041] As a preferred technical solution of the present invention, the additive manufacturing method further includes post-processing of the integrally formed superconducting cavity obtained in step (3); Preferably, the post-processing includes grinding, annealing, pickling, and washing in sequence.

[0042] The present invention can reduce the roughness of the inner surface of the superconducting cavity through post-processing, optimize its microstructure and stress distribution, and further improve the acceleration gradient and quality factor.

[0043] Thirdly, the present invention provides an application of a one-piece molded superconducting cavity for improving cooling efficiency as described in the first aspect in a superconducting accelerator.

[0044] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0045] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention integrates liquid helium pipes on the outer surface of the superconducting cavity body, so that the superconducting cavity can maintain an extremely low temperature of 2K with a small amount of liquid helium used during use, which can greatly reduce the cost of use. (2) The one-piece superconducting cavity provided by the present invention has a simple structure and a simple processing technology, and is suitable for industrial applications. Attached Figure Description

[0046] Figure 1 A schematic diagram of a one-piece superconducting cavity for improving cooling efficiency, provided for a specific embodiment of the present invention; Figure 2 A schematic cross-sectional view of a liquid helium pipeline provided for a specific embodiment of the present invention; Figure 3 This is a comparison curve of the quality factor Q0 of the superconducting cavity provided in Embodiment 1 and Comparative Example 1 of the present invention; Figure 4 This is a comparison curve of the quality factor Q0 of the superconducting cavity provided in Embodiment 2 and Comparative Example 2 of the present invention; Among them, 1 is the hollow cavity, 2 is the bundle tube, 3 is the liquid helium pipeline, 4 is the superconducting cavity interface flange, and 5 is the liquid helium interface flange. Detailed Implementation

[0047] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0048] In one specific embodiment, the present invention provides a one-piece molded superconducting cavity for improving cooling efficiency, such as... Figure 1 As shown, the integrally formed superconducting cavity includes: a superconducting cavity body and a liquid helium pipe 3 wound around the outer surface of the superconducting cavity body; The superconducting cavity body includes at least one hollow cavity 1, and a bundle tube 2 is fixedly disposed at both ends of the hollow cavity; The hollow cavity 1 is ellipsoidal; the major axis of the hollow cavity 1 is 75~410mm, and the minor axis is 40~410mm; The inner diameter of the bundle tube 2 is 30~156mm; a superconducting cavity interface flange 4 is provided at the end of the bundle tube 2 away from the hollow cavity 1; The distribution density of liquid helium pipes 3 on the outer surface of the hollow cavity 1 is higher than that on the outer surface of the bundle tube 2; and the hollow cavity is fixedly provided with liquid helium pipes 3 along its equator. The inner diameter of the liquid helium pipe 3 is 1~6mm; the liquid helium pipe 3 has a three-dimensional spiral or parallel channel cooling flow path; the inlet and outlet of the liquid helium pipe 3 are each independently provided with a liquid helium interface flange 5; such as Figure 2 As shown, the working distance between the inner surface of the liquid helium pipe 3 and the inner surface of the superconducting cavity body is 0.8~1.5mm.

[0049] In another specific embodiment, the additive manufacturing method for the integrally formed superconducting cavity for improving cooling efficiency includes the following steps: (1) Establish a three-dimensional model of the integral superconducting cavity, slice and layer the three-dimensional model, and convert it into STL format data and import it into the operating system of the 3D printing equipment; (2) Spread niobium powder evenly on the substrate of the molding working cavity of the 3D printing equipment and set the molding parameters; The niobium powder has a particle size range of 10~150μm, a sphericity ≥90%, an oxygen content ≤100ppm, and a nitrogen content ≤100ppm. (3) The integral superconducting cavity is obtained by repeatedly laser printing or electron beam melting printing in the molding chamber using an energy beam; The laser printing is performed in an inert gas environment; the power of the laser used in the laser printing is 300~500W; the laser scanning speed is 500~800mm / s; the laser scanning spacing is 0.01-0.03mm; the single-layer powder thickness is 20~40μm; and the substrate preheating temperature is 400~600℃. The vacuum level inside the forming chamber during electron beam melting printing is ≤2×10⁻⁶. -2 Pa; the power of the electron beam used is 300~3000W; the electron beam scanning spacing is 0.03~0.08mm; the single-layer powder thickness is 20~100μm; the substrate preheating temperature is 400~1300℃; (4) Post-process the integrally formed superconducting cavity described in step (3); The post-processing includes sequential grinding, annealing, pickling, and washing.

[0050] Example 1 This embodiment provides a one-piece molded superconducting cavity for improving cooling efficiency, such as... Figure 1 As shown, the integrally formed superconducting cavity has a specification of 650MHz-single cell and includes: a superconducting cavity body and a liquid helium pipe 3 wrapped around the outer surface of the superconducting cavity body; The superconducting cavity body includes a hollow cavity 1, and bundle tubes 2 are fixedly disposed at both ends of the hollow cavity; The hollow cavity 1 is ellipsoidal; the major axis and minor axis of the hollow cavity 1 are 410mm and 120mm respectively; The inner diameter of the bundle tube 2 is 156 mm; a superconducting cavity interface flange 4 is provided at the end of the bundle tube 2 away from the hollow cavity 1. The distribution density of liquid helium pipes 3 on the outer surface of the hollow cavity 1 is higher than that on the outer surface of the bundle tube 2; and a liquid helium pipe 3 is fixedly installed on the equator of the hollow cavity 1. The inner diameter of the liquid helium pipeline 3 is 3.5 mm; the liquid helium pipeline 3 has a three-dimensional spiral shape; the inlet and outlet of the liquid helium pipeline 3 are each independently equipped with a liquid helium interface flange 5; such as Figure 2 As shown, the working distance between the inner surface of the liquid helium pipe 3 and the inner surface of the superconducting cavity body is 1 mm.

[0051] The additive manufacturing method for improving cooling efficiency of the integrally formed superconducting cavity described in this embodiment includes the following steps: (1) Establish a three-dimensional model of the integral superconducting cavity, slice and layer the three-dimensional model, and convert it into STL format data and import it into the operating system of the 3D printing equipment; (2) Spread niobium powder evenly on the substrate of the molding working cavity of the 3D printing equipment and set the molding parameters; The niobium powder has a particle size range of 15~130μm, a sphericity of 95%, an oxygen content of 100ppm, and a nitrogen content of 100ppm. (3) Inert gas is introduced into the forming working cavity, and then laser printing is repeated to obtain the integrally formed superconducting cavity; In the laser printing process, the laser power used is 500W; the laser scanning speed is 700mm / s; the laser scanning spacing is 500mm; the single-layer powder thickness is 30μm; and the substrate preheating temperature is 600℃. (4) Post-process the integrally formed superconducting cavity described in step (3); The post-processing includes sequential grinding, annealing, pickling, and washing.

[0052] Example 2 This embodiment provides a one-piece molded superconducting cavity for improving cooling efficiency, such as... Figure 1 As shown, the integrally formed superconducting cavity has a specification of 1.3 GHz-single cell and includes: a superconducting cavity body and a liquid helium pipe 3 wrapped around the outer surface of the superconducting cavity body; The superconducting cavity body includes a hollow cavity 1, and bundle tubes 2 are fixedly disposed at both ends of the hollow cavity; The hollow cavity 1 is ellipsoidal; the major axis and minor axis of the hollow cavity 1 are 210 mm and 116 mm, respectively; The inner diameter of the bundle tube 2 is 78 mm; a superconducting cavity interface flange 4 is provided at the end of the bundle tube 2 away from the hollow cavity 1; The distribution density of liquid helium pipes 3 on the outer surface of the hollow cavity 1 is higher than that on the outer surface of the bundle tube 2; and a liquid helium pipe 3 is fixedly installed on the equator of the hollow cavity 1. The inner diameter of the liquid helium pipe 3 is 2 mm; the liquid helium pipe 3 has parallel channel-shaped cooling channels; the inlet and outlet of the liquid helium pipe 3 are each independently equipped with a liquid helium interface flange 5; such as Figure 2 As shown, the working distance between the inner surface of the liquid helium pipe 3 and the inner surface of the superconducting cavity body is 0.8 mm.

[0053] The additive manufacturing method for improving cooling efficiency of the integrally formed superconducting cavity described in this embodiment includes the following steps: (1) Establish a three-dimensional model of the integral superconducting cavity, slice and layer the three-dimensional model, and convert it into STL format data and import it into the operating system of the 3D printing equipment; (2) Spread niobium powder evenly on the substrate of the molding working cavity of the 3D printing equipment and set the molding parameters; The niobium powder has a particle size range of 10~100μm, a sphericity of 92%, an oxygen content of 80ppm, and a nitrogen content of 80ppm. (3) Inert gas is introduced into the forming working cavity, and then laser printing is repeated to obtain the integrally formed superconducting cavity; In the laser printing process, the laser power used is 420W; the laser scanning speed is 600mm / s; the laser scanning spacing is 600mm; the single-layer powder thickness is 40μm; and the substrate preheating temperature is 600℃. (4) Post-process the integrally formed superconducting cavity described in step (3); The post-processing includes sequential grinding, annealing, pickling, and washing.

[0054] Example 3 This embodiment provides a one-piece molded superconducting cavity for improving cooling efficiency, such as... Figure 1 As shown, the integrally formed superconducting cavity is 3.9 GHz-single cell and includes: a superconducting cavity body and a liquid helium pipe 3 wrapped around the outer surface of the superconducting cavity body; The superconducting cavity body includes a hollow cavity 1, and bundle tubes 2 are fixedly disposed at both ends of the hollow cavity; The hollow cavity 1 is ellipsoidal; the major axis of the hollow cavity 1 is 75mm and the minor axis is 40mm. The inner diameter of the bundle tube 2 is 30 mm; a superconducting cavity interface flange 4 is provided at the end of the bundle tube 2 away from the hollow cavity 1; The distribution density of liquid helium pipes 3 on the outer surface of the hollow cavity 1 is higher than that on the outer surface of the bundle tube 2; and a liquid helium pipe 3 is fixedly installed on the equator of the hollow cavity 1. The inner diameter of the liquid helium pipe 3 is 6 mm; the liquid helium pipe 3 has a three-dimensional spiral cooling channel; the inlet and outlet of the liquid helium pipe 3 are each independently equipped with a liquid helium interface flange 5; such as Figure 2 As shown, the minimum working distance between the inner surface of the liquid helium pipe 3 and the inner surface of the superconducting cavity body is 1 mm.

[0055] The additive manufacturing method for improving cooling efficiency of the integrally formed superconducting cavity described in this embodiment includes the following steps: (1) Establish a three-dimensional model of the integral superconducting cavity, slice and layer the three-dimensional model, and convert it into STL format data and import it into the operating system of the 3D printing equipment; (2) Spread niobium powder evenly on the substrate of the molding working cavity of the 3D printing equipment and set the molding parameters; The niobium powder has a particle size range of 30~110μm, a sphericity of 91%, an oxygen content of 80ppm, and a nitrogen content of 80ppm. (3) Inert gas is introduced into the molding working cavity, and then repeated electron beam melting printing is performed to obtain the integrally molded superconducting cavity; In the electron beam melting printing process, the electron beam power used is 800W; the electron beam scanning speed is 500mm / s; the scanning spacing is 0.01mm; the single-layer powder thickness is 20μm; and the substrate preheating temperature is 500℃. (4) Post-process the integrally formed superconducting cavity described in step (3); The post-processing includes sequential grinding, annealing, pickling, and washing.

[0056] Example 4 This embodiment provides a one-piece molded superconducting cavity for improving cooling efficiency. The only difference between this one-piece molded superconducting cavity for improving cooling efficiency and that of Embodiment 1 is: In this embodiment, the distribution density of the liquid helium pipes 3 on the outer surface of the hollow cavity 1 is adjusted to be lower than the distribution density of the liquid helium pipes 3 on the outer surface of the bundle tube 2.

[0057] The method for preparing the integrally molded superconducting cavity for improving cooling efficiency described in this embodiment is the same as that in Embodiment 1.

[0058] Example 5 This embodiment provides a one-piece molded superconducting cavity for improving cooling efficiency. The only difference between this one-piece molded superconducting cavity for improving cooling efficiency and that of Embodiment 1 is: In this embodiment, the liquid helium channels on the outer surface of the superconducting cavity are adjusted from a non-uniform distribution to a uniform distribution.

[0059] The method for preparing the integrally molded superconducting cavity for improving cooling efficiency described in this embodiment is the same as that in Embodiment 1.

[0060] Example 6 This embodiment provides a one-piece molded superconducting cavity for improving cooling efficiency. The only difference between this one-piece molded superconducting cavity for improving cooling efficiency and that of Embodiment 1 is: In this embodiment, the working distance between the inner surface of the liquid helium pipe 3 and the inner surface of the superconducting cavity body is adjusted to 2mm.

[0061] The method for preparing the integrally molded superconducting cavity for improving cooling efficiency described in this embodiment is the same as that in Embodiment 1.

[0062] Comparative Example 1 This comparative example provides a superconducting cavity, the structure of which is the same as that in Example 1.

[0063] This comparative example modifies the fabrication method of the superconducting cavity to traditional stamping and welding; the stamping and welding includes the following steps: Niobium sheets are stamped and welded to obtain a bundle tube, and niobium discs are stamped to obtain a semi-cavity. The semi-cavities are surface-treated, and the two semi-cavities are welded together to obtain an ellipsoidal hollow cavity, which is then welded to the bundle tube to obtain a superconducting cavity. Finally, the superconducting cavity is subjected to grinding, annealing, acid pickling, and water washing in sequence.

[0064] Comparative Example 2 This comparative example provides a superconducting cavity, the cavity shape of which is the same as that in Example 2.

[0065] In this comparative example, the preparation method of the superconducting cavity is adjusted to traditional stamping and welding; and the stamping and welding method is the same as that in Comparative Example 1.

[0066] Comparative Example 3 This comparative example provides a superconducting cavity for improving cooling efficiency, the cavity shape of which is the same as that in Example 3.

[0067] In this comparative example, the preparation method of the superconducting cavity is adjusted to traditional stamping and welding; and the stamping and welding method is the same as that in Comparative Example 1.

[0068] Application examples (1) Low-temperature vertical tests were performed on the superconducting cavities provided in Examples 1-2 and Comparative Examples 1-2, and the results are as follows: Figure 3 and Figure 4 As shown; according to Figure 3-4It can be seen that, under the same cavity shape conditions, the quality factor Q0 of the superconducting cavity obtained by additive manufacturing and the superconducting cavity obtained by traditional stamping and welding is close. However, the acceleration gradient of the superconducting cavity provided by the present invention is slightly better than that of comparative examples 1-2, which can better meet the technical indicators for actual use. (2) The amount of liquid helium required for the superconducting cavity provided in the above embodiments and comparative examples during operation is compared, and the results are shown in Table 1; among them, the superconducting cavity provided in comparative examples 1-3 needs to be immersed in liquid helium in a constant temperature chamber during operation to maintain low temperature; During operation, the temperature inside the superconducting cavity can be maintained at 2K.

[0069] Table 1 According to Table 1, the following points can be observed: (1) As can be seen from the comprehensive analysis of Examples 1-3, the one-piece superconducting cavity provided by the present invention can maintain an extremely low temperature of 2K under the premise of a small amount of liquid helium used during use, which can significantly reduce the cost of use; and the structure is simple and the processing technology is simple, making it suitable for industrial applications. (2) Comprehensive analysis of Examples 1 and 4-5 shows that if the distribution density of the liquid helium pipes wrapped around the outer surface of the superconducting cavity body is too small, the cooling efficiency will be poor; if it is too large, the amount of liquid helium used will be excessive. A comprehensive analysis of Examples 1 and 6 shows that if the working distance between the inner surface of the liquid helium pipe and the inner surface of the superconducting cavity is too high, it will affect the acceleration effect of the particles on the inner surface of the superconducting cavity. (3) The superconducting cavity provided in Comparative Examples 1-3 does not have a liquid helium pipeline. The reason is that if the liquid helium pipeline is welded and fixed on the outer surface of the superconducting cavity, the inner surface of the superconducting cavity is easily damaged during the welding process, causing product damage. Even if the superconducting cavity with a complete inner surface is obtained by external welding, there are gaps in the surface weld, which is not conducive to heat transfer.

[0070] A comprehensive analysis of Examples 1-3 and Comparative Examples 1-3 shows that the superconducting cavity prepared by the stamping and welding method needs to be immersed in liquid helium in a constant temperature chamber during operation to maintain the low temperature. The amount of liquid helium required is much higher than that in Examples 1-3, which further illustrates that the superconducting cavity provided by the present invention can significantly reduce the amount of liquid helium used and improve the cooling efficiency.

[0071] In summary, this invention, by integrally forming and winding a liquid helium pipe on the outer surface of the superconducting cavity body, enables the superconducting cavity to maintain an extremely low temperature of 2K during use with a small amount of liquid helium, which can significantly reduce the cost of use; moreover, the structure is simple, the processing technology is simple, and it is suitable for industrial applications.

[0072] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A one-piece molded superconducting cavity for improving cooling efficiency, characterized in that, The integrally formed superconducting cavity includes a superconducting cavity body and a liquid helium pipe wound around the outer surface of the superconducting cavity body; The superconducting cavity body includes at least one hollow cavity, and bundle tubes are fixedly disposed at both ends of the hollow cavity.

2. The integrally molded superconducting cavity for improving cooling efficiency according to claim 1, characterized in that, The hollow cavity is an ellipsoidal cavity; Preferably, the length of the major axis of the hollow cavity is 75~410mm, and the length of the minor axis is 40~410mm.

3. The integrally molded superconducting cavity for improving cooling efficiency according to claim 1 or 2, characterized in that, The inner diameter of the bundle tube is 30~156mm; Preferably, a superconducting cavity interface flange is provided at the end of the bundle tube away from the hollow cavity.

4. The integrally molded superconducting cavity for improving cooling efficiency according to any one of claims 1-3, characterized in that, The distribution density of liquid helium channels on the outer surface of the hollow cavity is higher than that on the outer surface of the bundle tube.

5. The integrally molded superconducting cavity for improving cooling efficiency according to any one of claims 1-4, characterized in that, The inner diameter of the liquid helium pipeline is 1~6mm; Preferably, the liquid helium pipeline has a three-dimensional spiral or parallel channel cooling flow path; Preferably, the inlet and outlet of the liquid helium pipeline are each independently provided with a liquid helium interface flange; Preferably, the working distance between the inner surface of the liquid helium pipe and the inner surface of the superconducting cavity body is 0.8~1.5mm.

6. An additive manufacturing method for an integrally formed superconducting cavity for improving cooling efficiency as described in any one of claims 1-5, characterized in that, The additive manufacturing method includes: (1) Establish a three-dimensional model of the integral superconducting cavity, slice and layer the three-dimensional model, and convert it into STL format data and import it into the operating system of the 3D printing equipment; (2) Spread niobium powder evenly on the substrate of the molding working cavity of the 3D printing equipment and set the molding parameters; (3) The integral superconducting cavity is obtained by repeatedly printing with an energy beam in the molding chamber; The printing includes laser printing or electron beam melting printing.

7. The additive manufacturing method according to claim 6, characterized in that, The particle size range of the niobium powder in step (2) is 10~150μm; Preferably, the sphericity of the niobium powder is ≥90%; Preferably, the niobium powder has an oxygen content ≤100ppm and a nitrogen content ≤100ppm.

8. The additive manufacturing method according to claim 6 or 7, characterized in that, The molding parameters in step (2) include energy beam power, energy beam scanning spacing, energy beam scanning speed, single-layer powder thickness, and substrate preheating temperature.

9. The additive manufacturing method according to any one of claims 6-8, characterized in that, The additive manufacturing method further includes post-processing of the integrally formed superconducting cavity obtained in step (3); Preferably, the post-processing includes grinding, annealing, pickling, and washing in sequence.

10. The application of a one-piece molded superconducting cavity for improving cooling efficiency as described in any one of claims 1-5 in a superconducting accelerator.

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