Preparation method of replicated ultra-cold neutron extraction conduit

Abstract

The invention discloses a preparation method of a replicated ultra-cold neutron extraction conduit, and belongs to the cross technical field of neutron optical device manufacturing and precision manufacturing, and the preparation method comprises the following steps: providing plate glass with the surface roughness superior to 0.5 nm as a substrate, and depositing a Ni / Ti neutron super mirror aperiodic multilayer film on the substrate by adopting a magnetron sputtering technology, the bottommost layer of the super-mirror multilayer film is a Ni layer in direct contact with the glass substrate, and the topmost layer is a Ti layer; a Cu seed layer continues to be sputtered and deposited on the non-periodic multilayer film of the Ni / Ti neutron super mirror, a mask plate is used in the sputtering process, and an uncoated blank area of 3-5 mm is reserved between the edge of the deposited film layer and the edge of the glass substrate. According to the method, a replication process route of super mirror preparation, seed layer deposition, precise electroplating, stress regulation and control, mechanical stripping and precise shaping is adopted, preparation of all high-performance film layers is completed on a super-smooth plane substrate, and it is ensured that the quality of the functional film is not limited by the geometrical shape of a base body.

Description

Technical Field

[0001] This invention belongs to the interdisciplinary field of neutron optical device manufacturing and precision manufacturing, and in particular, it relates to a method for preparing a replica-type ultracold neutron extraction conduit. Background Technology

[0002] Ultracold neutrons, due to their long wavelength and low energy, can undergo total internal reflection with the potential energy of matter, making them a key probe for studying cutting-edge physics questions such as neutron electric dipole moment and neutron lifetime. The extraction conduit, as the core transmission component connecting the ultracold neutron source and the experimental apparatus, must possess extremely high internal surface neutron reflectivity, excellent vacuum tightness, and superior stability in extremely low-temperature (liquid helium temperature) environments.

[0003] Due to their unique characteristics, ultracold neutron (UCN) conduits have extremely stringent requirements regarding surface quality, vacuum sealing, and stability in cryogenic environments. Currently, the most mainstream fabrication technology in this field is direct film deposition on the inner wall of metal or glass tubes. This approach typically uses stainless steel or quartz glass as the mechanical support, and the fabrication process is as follows: First, the inner wall of a cylindrical hollow metal or glass tube is mechanically polished to reduce surface roughness; then, a Ni / Ti neutron ultramirror film is directly deposited on the polished inner wall of the tube using physical vapor deposition (PVD) techniques such as magnetron sputtering and evaporation; finally, encapsulation and testing are performed.

[0004] While this traditional approach successfully addresses the fundamental issue of low-temperature stability, it suffers from two inherent drawbacks: First, polishing the inner wall of the cylindrical tube is extremely difficult, resulting in a surface roughness far inferior to that of finely polished flat glass (sub-nanometer roughness). This rough substrate surface leads to severe neutron scattering, causing a significant decrease in the reflectivity of the final supermirror film. Second, achieving uniform PVD coating within the high aspect ratio tubular geometry presents a significant technical challenge, easily leading to uneven film thickness distribution, increased structural defects, and poor film-substrate adhesion, further degrading the final performance of the conduit. These inherent drawbacks make it difficult for conduits prepared using this technique to meet the increasingly demanding transmission efficiency requirements of cutting-edge UCN experiments.

[0005] Although the above-mentioned "direct coating on the inner wall of the metal tube" technology solves the low-temperature stability problem, its inherent drawbacks severely limit the final performance of the ultracold neutron conduit. The specific drawbacks and their causes are as follows: The low neutron reflectivity and high transmission loss of the inner surface of ultracold neutron conduits are fundamentally due to two factors: First, the poor surface quality of the substrate. Ultracold neutron conduits are typically long, narrow cylinders with high aspect ratios (e.g., a length of 1 meter and a diameter of only a few centimeters). Precision polishing of the inner walls of such high aspect ratio metal or glass tubes is technically extremely challenging; their surface roughness (RMS) typically only reaches the tens of nanometers level, and defects such as polishing marks and microcracks are unavoidable. This rough surface produces strong non-mirror scattering of neutrons. Second, the poor quality of the film layer. Ultracold neutron conduits grown on rough substrates "replicate" or even amplify this unevenness, resulting in poor film density, severe interfacial diffusion, and an inability to form an ideal smooth film interface. The high reflectivity of ultracold neutron conduits precisely depends on the smoothness and integrity of the interfaces in the multilayer film structure. The dual disadvantages of the substrate and the film layer lead to a final conduit reflectivity far lower than the theoretical value.

[0006] The fabrication process is complex, resulting in poor performance consistency. This drawback stems directly from the inherent difficulties of the "high aspect ratio in-tube coating" process itself. First, process controllability is poor. Within the narrow tubular space, the incident angle, energy distribution, and plasma concentration of sputtered particles exhibit high non-uniformity, leading to severe unevenness in film thickness distribution along the axial and radial directions. This makes it difficult to precisely control the film thickness of the super mirror, significantly impacting performance. Second, repeatability is low. Even minor fluctuations in process parameters (such as target material loss or gas pressure changes) amplify the impact on the complex in-tube deposition environment, resulting in significant performance differences between different batches and even different locations within the same conduit. Third, cost is high and size is limited. Achieving high aspect ratio coating on the inner surface of a conduit requires specialized coating equipment, which is extremely complex and costly, fundamentally limiting the fabricable length and diameter of the conduit.

[0007] In summary, due to the inherent properties of the substrate material, the physical limitations of the high aspect ratio geometry, and the defects in the process route, the existing technology cannot fabricate ultracold neutron extraction conduits that simultaneously meet the requirements of "extremely high reflectivity" and "extremely high reliability," which seriously restricts the development of cutting-edge physics experiments. Summary of the Invention

[0008] The purpose of this invention is to provide a method for preparing a replicative ultracold neutron extraction conduit to solve the problems mentioned in the background art.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a replicative ultracold neutron extraction conduit, comprising: S1: Provide a flat glass substrate with a surface roughness better than 0.5 nm, and deposit a Ni / Ti neutron super mirror aperiodic multilayer film on the substrate using magnetron sputtering technology, wherein the bottom layer of the super mirror multilayer film is a Ni layer in direct contact with the glass substrate, and the top layer is a Ti layer. S2: Continue to sputter and deposit a Cu seed layer on the non-periodic multilayer film of the Ni / Ti neutron super mirror. During the sputtering process, a mask is used to leave a 3-5 mm uncoated blank area between the edge of the deposited film and the edge of the glass substrate. S3: The coated glass substrate obtained in step S2 is used as the cathode and placed in a special electroplating device with precise adjustable electrode spacing, multi-channel flow rate controllable circulation and online filtration functions. A large-area copper plate is used as the anode, and electrochemical electroplating is performed on the Cu seed layer to grow a copper support layer with a thickness of 100-200 μm, forming a composite film structure composed of a super mirror layer, a Cu seed layer and a copper support layer. S4: After cleaning the sample obtained in step S3 with deionized water, place it in a vacuum environment and bake it at 100-120℃ for 1-2 hours to release the internal stress of the composite membrane structure. S5: Cool the sample processed in step S4 to room temperature, use a blade to cut into the blank area reserved in step S2, and completely peel the composite film structure from the flat glass substrate by mechanical peeling to obtain an independent flexible composite film with one side being a super mirror functional surface and the other side being a copper support layer. S6: Cut the flexible composite film obtained by peeling and remove the edge area; wrap the cut composite film with its super mirror surface facing inward on the outer surface of the cylindrical polishing mandrel and roll it into a hollow cylindrical structure. S7: Laser welding technology is used to weld and seal the axial joints of the composite film after it is rolled up, forming an airtight hollow metal conduit; S8: On the outer wall of the welded conduit, weld several stainless steel sleeves at equal intervals along the axial direction to enhance the mechanical stability of the conduit. S9: Remove the internal polishing mandrel to obtain the final replica ultracold neutron extraction conduit.

[0010] In this preferred embodiment, the surface roughness Ra of the flat glass substrate is less than 0.5 nm, and the dimensions are 550 mm × 190 mm × 3 mm.

[0011] In this preferred embodiment, the Ni / Ti neutron mirror aperiodic multilayer film is of type m=2, with a total thickness of approximately 800 nm. It consists of more than 100 alternating Ni and Ti layers, and the thickness of each layer gradually decreases from the side closer to the glass substrate to the side farther away from the glass substrate.

[0012] In this preferred embodiment, the thickness of the Cu seed layer is 400 nm.

[0013] In this preferred embodiment, the electroplating solution used in the electrochemical electroplating is an acidic copper sulfate solution, and the process parameters include: cathode current density of 1.5 ASD ± 0.1 ASD, electrode spacing of 100 mm ± 5 mm, plating solution temperature of 25 ± 2°C, and circulation system flow rate of 10 L / min.

[0014] In this preferred embodiment, the dedicated electroplating device has precisely adjustable electrode spacing, multi-channel flow rate controllable circulation, and online filtration functions to ensure the uniformity of copper support layer thickness, crystal density, and internal stress distribution.

[0015] In this preferred embodiment, the thickness of the copper support layer grown by electrochemical plating is 150μm±5μm.

[0016] In this preferred embodiment, the vacuum level of the vacuum environment in step S4 is 10. -3 Pa, baking temperature is 120℃±2℃, and the holding time is 1.5 hours.

[0017] In the preferred embodiment of this scheme, in step S5, a peeling force is applied slowly and continuously along the surface of the glass substrate from the reserved 5mm blank area to achieve complete separation of the composite film structure from the glass substrate.

[0018] In this preferred embodiment, the composite film cut in step S6 has a size of 500mm × 157mm; in step S7, the composite film is rolled onto a polished mandrel with a diameter of Φ = 50mm, with its ultra-mirror surface facing inward, and the axial seams are aligned and then laser-welded to form a sealed axial longitudinal seam; in step S8, three stainless steel sleeves are welded at equal intervals along the axial direction on the outer wall of the conduit, and the interface of the sleeves is designed to be conical. This conical structure is used to avoid and expose the axial longitudinal seam to facilitate the implementation of the laser welding operation; after welding is completed, step S9 is performed to remove the internal polished mandrel to obtain a complete ultracold neutron extraction conduit.

[0019] Compared with the prior art, the technical effects and advantages of the present invention are as follows: The fabrication method of this replica ultracold neutron extraction conduit adopts a replication process route of "super mirror fabrication → seed layer deposition → precision electroplating → stress modulation → mechanical exfoliation → precise shaping". Through this specific process sequence, all high-performance films are fabricated on an ultra-smooth planar substrate, ensuring that the quality of the functional film (super mirror) is not limited by the substrate geometry. By utilizing the mature advantages of large-area, high-precision planar magnetron sputtering technology, combined with a specific film structure design (super mirror reverse film sequence), a non-periodic Ni / Ti super mirror multilayer film with smooth and clear interfaces and precisely controllable thickness is fabricated on an ultra-smooth glass substrate, thereby fundamentally ensuring that the inner surface of the conduit has a neutron reflectivity close to the theoretical limit.

[0020] A proprietary, parameter-adjustable precision electroplating process (rather than ordinary electroplating) is used to fabricate a copper support layer on the super mirror layer, characterized by uniform thickness, uniform internal stress distribution, and no defects. This process requires specialized equipment with specific functions (such as adjustable electrode spacing, multi-channel controllable flow fields, and online filtration) to ensure that it provides sufficient mechanical strength and can be smoothly peeled from the substrate and rolled into shape in subsequent processes.

[0021] Through a complete process design, including stress relief steps in heat treatment, precision mechanical stripping techniques, roll-to-roll encapsulation, and other steps, an all-metal, adhesive-free, intrinsically low-temperature stable, and internal surface optical quality guaranteed by the original substrate is finally obtained. Attached Figure Description

[0022] Figure 1 This is a flowchart illustrating a method for preparing a replicable ultracold neutron extraction conduit according to the present invention; Figure 2 This is a schematic diagram illustrating the preparation and structure of the composite film layer of the present invention; Figure 3 This is a schematic diagram of the product structure of the ultracold neutron extraction conduit of the present invention; Figure 4 This is a side view of the ultracold neutron extraction conduit of the present invention.

[0023] Explanation of reference numerals in the attached diagram: 1. Composite film; 2. Axial longitudinal seam; 3. Hoop. Detailed Implementation

[0024] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described in order to avoid obscuring the invention.

[0025] Unless otherwise defined, the directions mentioned herein, such as up, down, left, right, front, back, inside, and outside, are based on the directions shown in the figures of this invention, and are explained here together.

[0026] This embodiment provides, for example Figures 1 to 4 The method shown is a preparation method for a replica ultracold neutron extraction conduit. The core idea of ​​the method is to abandon the traditional approach of processing on the inner wall of the formed tube and instead adopt a replication technology path of "super mirror preparation → seed layer deposition → precision electroplating → stress control → precision peeling → roll welding". This method cleverly utilizes the mature advantages of planar technology to avoid all the processing difficulties brought about by the high aspect ratio three-dimensional structure.

[0027] The preparation method of this replica ultracold neutron extraction conduit includes the following steps: (1) Planar preparation of neutron super mirror film and Cu seed layer: First, an ultra-smooth flat glass substrate with a surface roughness better than 0.5 nm is used. A Ni / Ti neutron supermirror aperiodic multilayer film is deposited on the rectangular glass substrate using linear magnetron sputtering. The structure of the supermirror multilayer film is the reverse of the conventional order, with the bottom layer (the glass contact layer) being a Ni layer and the top layer being a Ti layer. Subsequently, a Cu seed layer with a thickness of several hundred nm is sputtered onto the supermirror layer. The purpose of depositing this Cu seed layer is twofold: firstly, to provide a good conductive substrate for subsequent electrochemical plating; and secondly, to utilize the excellent lattice matching and bonding force between the same material (copper) to ensure a strong and dense bonding interface between the electroplated copper layer and the sputtered functional film layer, preventing delamination. Crucially, a mask must be used during film deposition to leave a 3-5 mm gap between the film edge and the glass substrate edge. This design is a prerequisite for successful subsequent peeling, aiming to prevent the subsequent electroplated layer from encasing the glass edge, greatly reducing edge stress and peeling difficulty.

[0028] (2) Precision electroplating of the copper support layer: The coated glass substrate prepared in step (1) is used as the cathode and placed in a specialized device that meets the requirements of precision electroplating. A large-area copper plate is used as the anode, and electrochemical electroplating is performed on the Cu seed layer to grow a copper layer with a thickness of 100-200 μm, forming a composite film structure of super mirror layer / seed layer / copper support layer. The thickness of the copper support layer is controlled within the range of 100 to 200 micrometers to ensure that it has both good toughness and moderate rigidity, so as to meet the requirements of the subsequent roll forming process for the mechanical properties of the material. This step is one of the core steps of the method, requiring the specialized device to achieve functions such as "precisely adjustable electrode spacing", "multi-channel flow rate controllable circulation" and "online filtration" to ensure that the copper layer has uniform thickness, uniform internal stress distribution, dense crystallization and no defects.

[0029] (3) Stress relief and peeling of composite membrane: After electroplating, the sample is rinsed with deionized water and then subjected to a crucial heat treatment: baking in a vacuum environment at 100-120℃ for 1-2 hours. This process aims to expel the moisture adsorbed inside the film and actively regulate and release the internal stress of the composite film through uniform heating, thereby weakening its adhesion to the glass substrate. After heat treatment, at room temperature, a blade is used to cut into a pre-reserved blank area, and the entire composite film is slowly and continuously peeled off from the glass substrate, yielding an independent flexible film with a super mirror functional surface on one side and a copper support layer on the other.

[0030] (4) Coiling and sealing of the catheter: The composite film obtained by peeling is precisely cut to remove the electroplating defects at the edges; then, with the ultra-mirror side facing inward, it is wrapped around the surface of a polished mandrel of a specific diameter and rolled into a cylindrical shape; laser welding technology is used to weld and seal the axial seam to form a hollow conduit; finally, several hoops are welded and fixed to the outside of the conduit to enhance its mechanical stability.

[0031] The following description, in conjunction with the accompanying drawings, uses the fabrication of an ultracold neutron conduit with a length L=500 mm and a diameter Φ=50 mm as an example to illustrate the preferred embodiment of the present invention.

[0032] like Figure 1 and Figure 2 As shown, the complete preparation process of the present invention includes, in sequence: planar magnetron sputtering preparation of the super mirror layer and the seed layer; precision electroplating of the copper mechanical support layer; stress release and peeling of the composite film layer; and winding, welding and packaging of the conduit.

[0033] Step 1: Planar preparation of the super mirror layer and seed layer This step aims to prepare a functional film on a glass substrate. First, a highly polished flat glass substrate measuring 550 mm × 190 mm × 3 mm with a surface roughness Ra < 0.5 nm is provided. It is then placed in a linear magnetron sputtering deposition machine. A mask is used to cover the glass edges, leaving a 540 mm × 180 mm exposed area in the center. In this area, a Ni layer in contact with the glass surface is deposited first, followed by alternating Ni and Ti layers, for a total of more than 100 layers, forming a reverse-sequence m=2 Ni / Ti supermirror multilayer film (i.e., the film thickness varies from thick to thin) with a total thickness of approximately 800 nm. Subsequently, without breaking the vacuum, a 400 nm thick Cu seed layer is deposited on the supermirror layer in the same apparatus. This seed layer provides a conductive path for subsequent electroplating and ensures a strong interface using copper-copper bonding. One of the key features of this invention is that, through mask technology, a precise 5 mm blank area is left between the film edge and the glass substrate edge; this design is essential for successful subsequent peeling.

[0034] Step 2: Precision electroplating of the copper mechanical support layer This step is crucial in determining the coating quality. The aforementioned coated substrate is used as the cathode and installed in a dedicated electroplating apparatus capable of precise electrode spacing adjustment, multi-channel controllable circulation, and online filtration. Electroplating is performed using an acidic copper sulfate plating solution under the following optimized process parameters: cathode current density 1.5 ASD (±0.1 ASD), electrode spacing 100 mm (±5 mm), plating solution temperature 25 ±2°C, and circulation system flow rate 10 L / min. After approximately 15 hours of electroplating, a dense and uniform electroplated Cu support layer with a thickness of 150 μm (±5 μm) grows on the seed layer, forming a complete "super mirror / seed / support" sandwich structure composite film.

[0035] Step 3: Stress relief and peeling of the composite film This step is crucial for achieving "replication." After thoroughly cleaning the electroplated sample, a heat treatment process is performed: at 10... -3 Under a vacuum of Pa, the film is held at 120°C (±2°C) for 1.5 hours. This process effectively removes the moisture adsorbed in the film layer and actively and uniformly releases the internal stress of the composite film layer, significantly weakening its adhesion to the glass substrate. After cooling to room temperature, a blade is used to cut into the 5 mm blank area reserved in step one, and the entire composite film is mechanically peeled off completely with slow, uniform force and speed, obtaining an independent flexible film with one side being the super mirror functional surface and the other side being the copper support layer.

[0036] Step 4: Conduit rolling, welding and sealing The peeled film is precisely cut to a size of 500 mm × 157 mm, and edge defects are removed. For example... Figure 3 As shown, the ultra-mirror-like surface of the composite thin film 1 is wrapped around the smooth surface of a Φ50 mm mandrel, and rolled into a cylindrical shape. Laser welding is used to seal the longitudinal seam 2 along its axial direction, forming a vacuum-tight hollow conduit. Finally, three stainless steel sleeves 3 are welded at equal intervals to the outside of the conduit to enhance its mechanical stability. The interfaces of the sleeves 3 are designed to be tapered, exposing the longitudinal seam to facilitate laser welding. After removing the mandrel, the final complete ultracold neutron conduit is obtained.

[0037] The ultracold neutron extraction conduit prepared by the method in this embodiment inherits the ultrasmooth properties of the glass substrate on its inner surface, exhibits a clear interface of the supermirror film layer, and has a significantly higher neutron reflectivity than conduits prepared by traditional in-tube coating methods. The product has an all-metal structure and has passed thermal cycling tests at liquid helium temperatures, demonstrating excellent environmental stability and reliability, fully meeting the application requirements of cutting-edge UCN experiments.

[0038] It should be noted that, in this document, relational terms such as "one" and "two" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, the phrase "comprising an element defined as..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0039] 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 preparing a replicative ultracold neutron extraction conduit, characterized in that, include: S1: Provide a flat glass substrate with a surface roughness better than 0.5 nm, and deposit a Ni / Ti neutron super mirror aperiodic multilayer film on the substrate using magnetron sputtering technology, wherein the bottom layer of the super mirror multilayer film is a Ni layer in direct contact with the glass substrate, and the top layer is a Ti layer. S2: Continue to sputter and deposit a Cu seed layer on the non-periodic multilayer film of the Ni / Ti neutron super mirror. During the sputtering process, a mask is used to leave a 3-5 mm uncoated blank area between the edge of the deposited film and the edge of the glass substrate. S3: The coated glass substrate obtained in step S2 is used as the cathode and placed in a special electroplating device with precise adjustable electrode spacing, multi-channel flow rate controllable circulation and online filtration functions. A large-area copper plate is used as the anode, and electrochemical electroplating is performed on the Cu seed layer to grow a copper support layer with a thickness of 100-200 μm, forming a composite film structure composed of a super mirror layer, a Cu seed layer and a copper support layer. S4: After cleaning the sample obtained in step S3 with deionized water, place it in a vacuum environment and bake it at 100-120℃ for 1-2 hours to release the internal stress of the composite membrane structure. S5: Cool the sample processed in step S4 to room temperature, use a blade to cut into the blank area reserved in step S2, and completely peel the composite film structure from the flat glass substrate by mechanical peeling to obtain an independent flexible composite film with one side being a super mirror functional surface and the other side being a copper support layer. S6: Cut the flexible composite film obtained by peeling and remove the edge area; wrap the cut composite film with its super mirror surface facing inward on the outer surface of the cylindrical polishing mandrel and roll it into a hollow cylindrical structure. S7: Laser welding technology is used to weld and seal the axial joints of the composite film after it is rolled up, forming an airtight hollow metal conduit; S8: On the outer wall of the welded conduit, weld several stainless steel sleeves at equal intervals along the axial direction to enhance the mechanical stability of the conduit. S9: Remove the internal polishing mandrel to obtain the final replica ultracold neutron extraction conduit.

2. The method for preparing a replicative ultracold neutron extraction conduit according to claim 1, characterized in that: The surface roughness Ra of the flat glass substrate is less than 0.5 nm, and its dimensions are 550 mm × 190 mm × 3 mm.

3. The method for preparing a replicative ultracold neutron extraction conduit according to claim 1, characterized in that: The Ni / Ti neutron supermirror aperiodic multilayer film is of type m=2, with a total thickness of approximately 800 nm. It consists of more than 100 alternating Ni and Ti layers, and the thickness of each layer gradually decreases from the side closer to the glass substrate to the side farther away from the glass substrate.

4. The method for preparing a replicative ultracold neutron extraction conduit according to claim 1, characterized in that: The thickness of the Cu seed layer is 400 nm.

5. The method for preparing a replicative ultracold neutron extraction conduit according to claim 1, characterized in that: The electroplating solution used in the electrochemical electroplating is an acidic copper sulfate solution. The process parameters include: cathode current density of 1.5 ASD ±0.1 ASD, electrode spacing of 100 mm ± 5 mm, plating solution temperature of 25 ± 2°C, and circulation system flow rate of 10 L / min.

6. The method for preparing a replicative ultracold neutron extraction conduit according to claim 1, characterized in that: The dedicated electroplating device features precisely adjustable electrode spacing, multi-channel flow rate controllable circulation, and online filtration functions to ensure the uniformity of copper support layer thickness, crystal density, and internal stress distribution.

7. The method for preparing a replicative ultracold neutron extraction conduit according to claim 1, characterized in that: The thickness of the copper support layer grown by electrochemical plating is 150 μm ± 5 μm.

8. The method for preparing a replicative ultracold neutron extraction conduit according to claim 1, characterized in that: The vacuum level of the vacuum environment in step S4 is 10. -3 Pa, baking temperature is 120℃±2℃, and the holding time is 1.5 hours.

9. The method for preparing a replicative ultracold neutron extraction conduit according to claim 1, characterized in that: In step S5, a peeling force is applied slowly and continuously along the surface of the glass substrate from the reserved 5mm blank area to achieve complete separation of the composite film structure from the glass substrate.

10. The method for preparing a replicative ultracold neutron extraction conduit according to claim 1, characterized in that: In S6, the size of the cut composite film (1) is 500mm×157mm; in S7, the composite film (1) is rolled on a polished mandrel with a diameter of Φ=50mm, with its super mirror surface facing inward, and after the axial joints are aligned, a sealed axial longitudinal seam (2) is formed by laser welding; in S8, three stainless steel sleeves (3) are welded at equal intervals along the axial direction on the outer wall of the conduit, and the interface of the sleeves (3) is designed to be conical. This conical structure is used to avoid and expose the axial longitudinal seam (2) so as to facilitate the implementation of laser beam welding operation; after welding is completed, S9 is executed to remove the internal polished mandrel and obtain a complete ultracold neutron extraction conduit.

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