A polycrystalline film-based tritium pre-target and method of manufacture thereof

Abstract

This invention relates to a pre-fabricated tritium target based on a polycrystalline film and its manufacturing method, belonging to the field of plasma technology. The pre-fabricated tritium target includes an oxygen-free copper target substrate, a first zirconium film, a high-entropy ceramic tritium-blocking layer, and a second zirconium film sequentially deposited on its surface. The manufacturing method includes: pre-treating the oxygen-free copper target substrate; sequentially depositing multiple layers of films using a magnetron sputtering process to form a polycrystalline film layer; purging the oxygen-free copper target substrate with the polycrystalline film layer with tritium; and bonding the oxygen-free copper target substrate to an oxygen-free copper target holder. The pre-fabricated tritium target based on a polycrystalline film of this invention solves the problem of balancing heat dissipation and tritium blocking performance in traditional processes, achieving a balance between heat dissipation and tritium blocking capabilities. This allows the prepared pre-fabricated tritium target to be reused, improving the utilization rate of the pre-fabricated tritium target and reducing the cost of using neutron tubes.

Description

Technical Field

[0001] This invention belongs to the field of plasma technology, specifically relating to a pre-fabricated tritium target based on a polycrystalline film and its manufacturing method. Background Technology

[0002] Pre-fabricated tritium targets are core functional components that utilize tritium to generate neutrons or specific radiation, playing a crucial role in scientific research, industry, and nuclear energy. The primary application of pre-fabricated tritium targets is as a controllable, high-current neutron source. Its core principle is the deuterium-tritium fusion reaction: a high-energy deuterium ion beam generated by an accelerator bombards a tritium-containing target material, causing the deuterium nuclei to combine with tritium nuclei and release fast neutrons with energies up to 14.1 MeV. These neutrons possess excellent monochromaticity and high yield, and are widely used in neutron radiography for non-destructive probing of the internal structure of objects, particularly suitable for detecting hydrogen-containing materials, heavy metal components, and nuclear fuel elements.

[0003] Another important application of prefabricated tritium targets is as a portable, low-power X-ray source. The principle is to use beta particles generated by tritium decay to bombard the target material, producing bremsstrahlung radiation, i.e., low-energy X-rays. This property can be used to manufacture handheld X-ray fluorescence analyzers. In addition, pure tritium targets also serve as stable beta radiation sources in electron capture detectors of gas chromatographs. The core challenge in the development of prefabricated tritium targets lies in how to maintain a high tritium density stably over a long period under extreme conditions of high-energy ion beam bombardment (such as high heat flux density and strong radiation damage).

[0004] Currently, common prefabricated tritium targets mainly employ two structures: one uses pure molybdenum as the target substrate, coats it with a titanium film, and then fills it with tritium to form a tritium-titanium target; the other uses oxygen-free copper as the target substrate, similarly coated with a titanium film and then filled with tritium. The former achieves good tritium blocking effect by utilizing the molybdenum substrate and titanium film, but molybdenum has poor thermal conductivity at high temperatures, causing heat from the target surface to be unable to be dissipated in time, easily leading to damage to the titanium tritide layer and tritium leakage. The latter utilizes the excellent thermal conductivity of oxygen-free copper for heat dissipation, but oxygen-free copper itself has almost no tritium blocking ability; if there are defects in the surface titanium film, tritium will quickly dissipate through the copper substrate.

[0005] Since the two existing solutions mentioned above focus on either heat dissipation or tritium blocking, respectively, they cannot simultaneously meet the dual requirements of efficient heat dissipation and effective tritium blocking under high-temperature operating conditions. Furthermore, due to the significant difference in the coefficients of thermal expansion between the ceramic film and the metal substrate, direct deposition is prone to cracking or peeling of the film layer due to thermal stress, further limiting the design and application of composite film layer structures that combine heat dissipation and tritium blocking functions. Summary of the Invention

[0006] To address the aforementioned problems in the prior art, this invention provides a pre-fabricated tritium target based on a polycrystalline film and its manufacturing method. The technical problem to be solved by this invention is achieved through the following technical solution: This invention provides a pre-fabricated tritium target based on a polycrystalline film, comprising: Oxygen-free copper target; A polycrystalline film is deposited on the first surface of the oxygen-free copper target substrate; the polycrystalline film comprises: a first zirconium metal film, a high-entropy ceramic tritium barrier layer, and a second zirconium metal film, which are sequentially deposited from the inside to the outside. An oxygen-free copper target holder is fixed to the second surface of the oxygen-free copper target base; The oxygen-free copper target substrate is used to provide the main heat dissipation path. The first metallic zirconium film forms an ductile transition layer to buffer the thermal stress between the oxygen-free copper target substrate and the high-entropy ceramic tritium barrier layer. The high-entropy ceramic tritium barrier layer is used to provide a tritium barrier. The second metallic zirconium film, as a tritium-filled layer, combines with tritium to form a zirconium tritide layer.

[0007] In one embodiment of the present invention, the high-entropy ceramic tritium barrier layer is a pentagonal nitride ceramic with the chemical formula (AlCrTaTiZr)N.

[0008] In one embodiment of the present invention, the first zirconium film, the high-entropy ceramic tritium barrier layer and the second zirconium film have the same thickness, which ranges from 3 μm to 5 μm.

[0009] In one embodiment of the present invention, in the zirconium tritide layer formed by filling the second zirconium metal film with tritium, the atomic ratio of tritium to zirconium is not less than 1.6:1.

[0010] In one embodiment of the present invention, the first surface of the oxygen-free copper target substrate is concave, and the first zirconium metal film, the high-entropy ceramic tritium barrier layer and the second zirconium metal film are sequentially deposited on the concave surface of the oxygen-free copper target substrate. The second surface of the oxygen-free copper target base is disposed opposite to the first surface, and the second surface of the oxygen-free copper target base is bonded to the oxygen-free copper target holder by brazing; the oxygen-free copper target holder is sealed to the neutron tube shell by argon arc welding.

[0011] This invention also provides a method for manufacturing a pre-tritium target based on a polycrystalline film, used to prepare the aforementioned pre-tritium target based on a polycrystalline film, the method comprising: S1: Prepare oxygen-free copper target substrate and pretreat tritium target components; S2: On the surface of the oxygen-free copper target substrate, a first zirconium film, a high-entropy ceramic tritium barrier layer and a second zirconium film are sequentially deposited using a magnetron sputtering process to form a polycrystalline film layer. S3: The oxygen-free copper target substrate coated with the polycrystalline film is subjected to tritium purging treatment, so that tritium combines with the second metallic zirconium film to form a zirconium tritide layer; S4: The oxygen-free copper target substrate with the zirconium tritide layer is bonded to the oxygen-free copper target holder by brazing, thus completing the manufacturing of the pre-made tritium target.

[0012] In one embodiment of the present invention, S1, the pretreatment of the tritium target component includes: sequentially performing degreasing, pickling, neutralization, dehydration and vacuum high-temperature degassing treatment on the oxygen-free copper target substrate; The vacuum high-temperature degassing process includes: sequentially heating the oxygen-free copper target substrate from room temperature to various preset temperatures in a vacuum environment, and maintaining the temperature at each preset temperature. Each preset temperature is between room temperature and 850°C and increases sequentially in steps. The preset temperatures are room temperature, 200°C, 400°C, 450°C, 700°C and 850°C.

[0013] In one embodiment of the present invention, S2 includes: S2.1: Place the first set of sputtering targets, heat the oxygen-free copper target substrate to 400°C to 450°C, and maintain the vacuum level in the cavity at 2×10⁻⁶. - ¹Pa to 3×10 - Between ¹Pa, a magnetron sputtering process is used, with pre-sputtering for 10 to 15 minutes at a sputtering power of 120W to 480W; S2.2: The first metallic zirconium film is formed by sputtering at a sputtering power of 120W to 480W for 30 to 50 minutes using a magnetron sputtering process. S2.3: The oxygen-free copper target substrate coated with the first metal zirconium film is placed in a high vacuum degassing furnace and subjected to high-temperature curing treatment at 850°C. S2.4: Place the second set of sputtering targets, and after vacuum high-temperature degassing of the oxygen-free copper target substrate coated with the first zirconium film, heat it again to 400℃ to 450℃, maintaining the vacuum level in the cavity at 2×10⁻⁶. - ¹Pa to 3×10 - Between ¹Pa, pre-sputtering is performed using magnetron sputtering process for 5 to 10 minutes; S2.5: A high-entropy ceramic tritium barrier layer is deposited in a mixed atmosphere of nitrogen and argon using magnetron sputtering at a sputtering power of 480W. S2.6: Insert the third set of sputtering targets, maintaining a vacuum level of 2×10⁻⁶ within the cavity. - ¹Pa to 3×10 - Between ¹Pa, a magnetron sputtering process is used, with pre-sputtering for 10 to 15 minutes at a sputtering power of 120W to 480W; S2.7: Using magnetron sputtering, a second metallic zirconium film is deposited by sputtering at a sputtering power of 120W to 480W for 30 to 50 minutes to obtain a polycrystalline film layer.

[0014] In one embodiment of the present invention, in S2, when the high-entropy ceramic tritium barrier layer is deposited by magnetron sputtering, independent sputtering targets made of five metal elements, Al, Cr, Ta, Ti and Zr, are used, and magnetron sputtering is performed in a mixed atmosphere of nitrogen and argon. The purity of each individual sputtering target is not less than 99.99% for a single metal; the volume percentage of nitrogen in the mixed atmosphere is 20%, and the purity of both nitrogen and argon is not less than 99.99% for a single gas.

[0015] In one embodiment of the present invention, in S3, the tritium filling process adopts a stepped cooling tritium filling process, including: filling tritium gas at a constant temperature of 500°C to 550°C, gradually cooling down in a cooling step range of 50°C to 100°C, maintaining a constant temperature for each cooling step for 30 minutes to 40 minutes, until the temperature drops to 200°C to 250°C, then recovering the tritium gas in the cavity and allowing it to cool naturally to room temperature.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: The pre-fabricated tritium target based on a polycrystalline film of the present invention effectively solves the problem of the inability to simultaneously achieve heat dissipation and tritium blocking performance in the prior art through a polycrystalline film structure consisting of a first zirconium film, a high-entropy ceramic tritium blocking layer, and a second zirconium film with tritium filling the surface. Specifically, the oxygen-free copper target substrate provides the main heat dissipation path, ensuring that the working heat is rapidly dissipated; the first zirconium film, as an extensible transition layer, effectively buffers the thermal expansion mismatch stress between the oxygen-free copper target substrate and the high-entropy ceramic tritium blocking layer, protecting the integrity of the tritium blocking barrier; the high-entropy ceramic layer forms a tritium blocking barrier with its dense lattice, reducing tritium permeation and loss; the surface second zirconium film provides a tritium bonding interface, forming a high-density stable tritide, increasing the yield of the neutron tube. Through the synergistic cooperation of each layer in the polycrystalline film structure, both heat dissipation performance and tritium blocking capability are balanced, allowing the prepared pre-fabricated tritium target to be reused, improving the utilization rate of the pre-fabricated tritium target, and reducing the cost of using the neutron tube.

[0017] The present invention provides a method for manufacturing pre-tritium targets based on polycrystalline films. Through process steps including pretreatment and multilayer magnetron sputtering deposition, the method ensures high-quality fabrication of pre-tritium targets based on polycrystalline films. Specifically, the pretreatment and degassing processes provide a clean and stable substrate interface for film bonding; sequentially depositing a first zirconium film as a transition layer, a high-entropy ceramic tritium barrier layer, and a second zirconium film as a tritium-filling layer constructs a functionally distinct polycrystalline film structure.

[0018] This invention optimizes the diffusion and bonding process of tritium in the surface zirconium film through a stepped cooling tritium filling process, promotes the formation of a highly stable zirconium tritide layer, ensures the stability of the pre-fabricated tritium target under high temperature conditions, and improves the service life of the neutron tube.

[0019] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a neutron tube using a pre-fabricated tritium target based on a polycrystalline film, provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of a pre-fabricated tritium target based on a polycrystalline film provided in an embodiment of the present invention; Figure 3 This is provided by the embodiments of the present invention. Figure 2 Enlarged view of the local structure at point I; Figure 4 This is a cross-sectional schematic diagram of the polycrystalline film provided in an embodiment of the present invention; Figure 5 This is a flowchart of a pre-fabricated tritium target manufacturing method based on a polycrystalline film provided in an embodiment of the present invention; Figure 6 This is a flowchart of step S2 in the pre-fabricated tritium target manufacturing method based on a polycrystalline film provided in an embodiment of the present invention; Figure 7 This is a process flow diagram of the pre-fabricated tritium target manufacturing method based on polycrystalline film provided in the embodiments of the present invention.

[0021] Figure reference numerals: 1-Oxygen-free copper target substrate; 11-First surface; 12-Second surface; 2-Polycrystalline film layer; 21-First metallic zirconium film; 22-High-entropy ceramic tritium barrier layer; 23-Second metallic zirconium film; 3-Oxygen-free copper target holder; 4-Neutron tube shell. Detailed Implementation

[0022] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a method for manufacturing a pre-fabricated tritium target based on a polycrystalline film according to the present invention.

[0023] The foregoing and other technical contents, features, and effects of the present invention will be clearly presented in the following detailed description of specific embodiments in conjunction with the accompanying drawings. Through the description of the specific embodiments, a more in-depth and concrete understanding can be gained of the technical means and effects adopted by the present invention to achieve its intended purpose. However, the accompanying drawings are for reference and illustration only and are not intended to limit the technical solutions of the present invention.

[0024] Example 1 like Figures 1 to 4 As shown, Figure 1 This is a schematic diagram of a neutron tube using a pre-fabricated tritium target based on a polycrystalline film, provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of a pre-fabricated tritium target based on a polycrystalline film provided in an embodiment of the present invention; Figure 3 This is provided by the embodiments of the present invention. Figure 2 Enlarged view of the local structure at point I; Figure 4 This is a cross-sectional schematic diagram of the polycrystalline film provided in an embodiment of the present invention.

[0025] This embodiment provides a prefabricated tritium target based on a polycrystalline film, comprising: an oxygen-free copper target substrate 1, a polycrystalline film layer 2, and an oxygen-free copper target holder 3; the polycrystalline film layer 2 is deposited on the first surface 11 of the oxygen-free copper target substrate 1; the polycrystalline film layer 2 includes: a first zirconium metal film 21, a high-entropy ceramic tritium blocking layer 22, and a second zirconium metal film 23, which are sequentially deposited from the inside to the outside; the oxygen-free copper target holder 3 is fixed to the second surface 12 of the oxygen-free copper target substrate 1; the first surface 11 of the oxygen-free copper target substrate 1 is concave, and the first zirconium metal film 21, the high-entropy ceramic tritium blocking layer 22, and the second zirconium metal film 23 are sequentially deposited on the concave surface of the oxygen-free copper target substrate 1; the second surface 12 of the oxygen-free copper target substrate 1 is disposed opposite to the first surface 11, and the second surface 12 of the oxygen-free copper target substrate 1 is bonded to the oxygen-free copper target holder 3 by brazing, and the oxygen-free copper target holder 3 is sealed to the neutron tube shell 4 by argon arc welding.

[0026] Among them, the oxygen-free copper target 1 is used to provide the main heat dissipation path, the first metallic zirconium film 21 forms an ductile transition layer to buffer the thermal stress between the oxygen-free copper target 1 and the high-entropy ceramic tritium barrier layer 22, the high-entropy ceramic tritium barrier layer 22 is used to provide a tritium barrier, and the second metallic zirconium film 23 serves as a tritium-filled layer and combines with tritium to form a zirconium tritide layer.

[0027] Preferably, the oxygen-free copper material used in the oxygen-free copper target 1 has a purity of not less than 99.998% to ensure its heat dissipation performance.

[0028] In an optional embodiment, the high-entropy ceramic tritium barrier layer 22 is a pentagonal nitride ceramic with the chemical formula (AlCrTaTiZr)N. Preferably, the high-entropy ceramic tritium barrier layer 22 is deposited using individual sputtering targets made of five metal elements: aluminum (Al), chromium (Cr), tantalum (Ta), titanium (Ti), and zirconium (Zr), respectively, through a magnetron sputtering process. The purity of each individual metal in the sputtering target is not less than 99.99%, thereby ensuring the quality of the high-entropy ceramic tritium barrier layer 22.

[0029] In one optional embodiment, the first zirconium film 21, the high-entropy ceramic tritium barrier layer 22, and the second zirconium film 23 have the same thickness, i.e., the thickness ratio of the first zirconium film 21, the high-entropy ceramic tritium barrier layer 22, and the second zirconium film 23 is 1:1:1, and the thickness range of all three is 3μm to 5μm. It is understood that if the coating is too thick, stress can easily lead to uneven film layer, or the appearance of pores and cracks, thereby reducing the film layer's density, increasing the risk of cracking, and causing problems such as decreased adhesion. Conversely, if the film layer is too thin, it will lead to discontinuity in the film layer, as well as insufficient film layer function and poor adhesion, ultimately affecting the stability and service life of the film layer.

[0030] Low-purity zirconium films not only reduce the density of tritium adhering to the surface, but also affect the stability of the zirconium film due to trace elements inside the crystal lattice, which can easily lead to oxidation and peeling. Preferably, the zirconium (Zr) material used in the first metallic zirconium film 21 and the second metallic zirconium film 23 has a purity of not less than 99.999%, thereby ensuring the quality of the first metallic zirconium film 21 and the second metallic zirconium film 23.

[0031] Furthermore, in the tritium-filled zirconium tritide layer formed by the second metallic zirconium film 23, the atomic ratio of tritium to zirconium is not less than 1.6:1.

[0032] It is worth noting that the pre-fabricated tritium target based on polycrystalline film in this embodiment, through the polycrystalline film layer 2 structure composed of a first zirconium metal film 21, a high-entropy ceramic tritium blocking layer 22 and a tritium-filled second zirconium metal film 23, effectively solves the problem that heat dissipation and tritium blocking performance cannot be simultaneously achieved in the prior art.

[0033] Specifically, the oxygen-free copper target base 1 provides the main heat dissipation path. The oxygen-free copper target base 1 is brazed to the oxygen-free copper target holder 3, which is then sealed to the neutron tube shell 4 via argon arc welding. This structure increases the overall heat dissipation area of ​​the prefabricated tritium target. The oxygen-free copper target holder 3 facilitates heat exchange between the neutron tube and the external environment, ensuring rapid heat dissipation. Thus, when the neutron tube operates at high temperatures, the heat generated by nuclear fusion can be guided from the oxygen-free copper target base 1 to the oxygen-free copper target holder 3, and then rapidly introduced into the external medium by the oxygen-free copper target holder 3.

[0034] Since the ductility of the oxygen-free copper target 1 and the high-entropy ceramic tritium barrier layer 22 differs significantly, a first metallic zirconium film 21 is used as a ductility transition layer before depositing the high-entropy ceramic tritium barrier layer 22. This effectively buffers the thermal expansion mismatch stress between the oxygen-free copper target 1 and the high-entropy ceramic tritium barrier layer 22, preventing the high-entropy ceramic tritium barrier layer 22 from being damaged by the thermal expansion mismatch stress, thereby protecting the integrity of the tritium barrier.

[0035] The high-entropy ceramic tritium barrier layer 22 integrates nitrides of five metal elements. Through its high-entropy effect and disordered dense lattice structure, it achieves comprehensive performance that surpasses that of traditional ceramics. Specifically, the high-entropy ceramic tritium barrier layer 22 has extremely low isotope permeability. Tritium is mainly physically adsorbed on its surface, resulting in a high diffusion energy barrier. Thus, its dense lattice forms a tritium barrier, reducing the permeation and loss of tritium.

[0036] The second zirconium metal film 23 on the surface provides a tritium binding interface, forming a high-density stable tritide. Compared with the high-purity titanium film, the zirconium metal film has better performance and tritium locking performance, thereby increasing the yield of neutron tubes.

[0037] Through the synergistic cooperation of each layer in the polycrystalline film layer 2 structure, both heat dissipation performance and tritium blocking capability are taken into account, so that the prepared pre-tritium target can be reused, improving the utilization rate of the pre-tritium target and reducing the cost of using the neutron tube.

[0038] Example 2 like Figure 5 As shown, Figure 5 This is a flowchart of a pre-fabricated tritium target manufacturing method based on a polycrystalline film provided in an embodiment of the present invention.

[0039] This embodiment provides a method for manufacturing a pre-tritium target based on a polycrystalline film, used to prepare the pre-tritium target based on a polycrystalline film of Example 1. The method includes S1 to S4, which are described in detail below: S1: Prepare oxygen-free copper target substrate and pretreat tritium target components.

[0040] In an optional embodiment, in S1, the pretreatment of the tritium target component includes: sequentially performing degreasing, pickling, neutralization, dehydration, and vacuum high-temperature degassing treatment on the oxygen-free copper target substrate in a vacuum environment.

[0041] For example, since the surface of the oxygen-free copper target substrate is prone to oxidation to form copper oxide and cuprous oxide under normal temperature conditions, it needs to be reduced with nitric acid of a certain concentration before being coated using the magnetron sputtering process. Specifically, the surface of the oxygen-free copper target substrate is first degreased with aviation gasoline, then acid-washed with nitric acid, and finally the residual nitric acid solution on the surface of the oxygen-free copper target substrate is neutralized and dehydrated. After that, it is vacuum-sealed and transferred to the next process for vacuum high-temperature degassing treatment.

[0042] Understandably, a similar pretreatment process is used for Al targets, which are also prone to oxidation at room temperature. For other targets that are not prone to oxidation, such as Cr, Ta, Ti and Zr targets, only degreasing, dehydration and vacuum high-temperature degassing treatment are required.

[0043] In an optional embodiment, the vacuum high-temperature degassing process includes: sequentially heating the oxygen-free copper target substrate from room temperature to various preset temperatures, and maintaining a constant temperature at each preset temperature. The preset temperatures are between room temperature and 850°C and increase in a stepwise manner. The preset temperatures are room temperature, 200°C, 400°C, 450°C, 700°C and 850°C, respectively. The preset temperatures and the constant temperature holding times are shown in Table 1.

[0044] For example, at room temperature, the surface and internal lattice of metal parts will adsorb a large amount of impurities. Directly applying magnetron sputtering coating to an oxygen-free copper target substrate will cause the target substrate to oxidize, thereby contaminating the magnetron sputtering equipment. Therefore, a vacuum high-temperature degassing treatment is required before magnetron sputtering coating. Taking oxygen-free copper as an example, considering that the melting point of oxygen-free copper is 1380℃, the degassing temperature can be set relatively high, which can both degas the parts and eliminate stress. The degassing temperature process is shown in Table 1.

[0045] Table 1. Degassing temperature process for oxygen-free copper target substrate

[0046] A stepped heating program was employed to heat the oxygen-free copper target substrate under vacuum. First, the target substrate was heated from room temperature to 200°C at a uniform rate over 30 minutes, and then held at 200°C for 10 minutes. Next, the temperature was increased to 400°C over 30 minutes, followed by a further increase to 450°C and a holding time of 10 minutes. The temperature was then further increased to 700°C over 40 minutes, followed by a holding time of 10 minutes. Finally, the temperature was raised to 850°C over 40 minutes, and then held at 850°C for a final stage of isothermal treatment for 10 minutes to ensure thorough removal of adsorbed gases and stress release. By controlling the heating rate and the holding time at each temperature plateau, efficient and thorough degassing and stress relief of the oxygen-free copper target substrate were achieved.

[0047] Similarly, pretreatment of tritium target components also includes: for easily oxidized target materials, vacuum high-temperature degassing treatment can be used. For example, for Al target materials, the Al target material is sequentially heated and cooled from room temperature in a vacuum environment, and then held at each preset temperature. The degassing temperature process is shown in Table 2. Specifically, the Al target material is placed in a vacuum environment and first heated from room temperature to 200°C at a uniform rate, which takes 30 minutes; after reaching 200°C, it is held at a constant temperature for 10 minutes; then it is heated to 400°C, which takes 30 minutes, and then held at 400°C for 120 minutes to fully remove the gas adsorbed inside the material. The cooling process then begins: first, the temperature is lowered from 400°C to 350°C over 40 minutes, and then held at 350°C for 10 minutes; next, the temperature is lowered to 200°C over another 40 minutes, and then held at 200°C for 10 minutes. Finally, the target material is allowed to cool naturally to room temperature. In this way, by controlling the temperature rise and fall steps, complete degassing of the Al target material is achieved while avoiding material damage caused by excessive thermal stress.

[0048] Table 2 Degassing temperature process for Al targets

[0049] Furthermore, in the vacuum high-temperature degassing process, the Al target material employs a stepped heating and cooling process. Specifically, after the Al target material is steppedly heated to 450℃ and thoroughly degassed at a constant temperature, a stepped cooling process is then implemented from 450℃ down to 200℃, with each preset temperature maintained at a constant temperature. This process is used because aluminum has a high coefficient of thermal expansion and is sensitive to temperature changes. Sudden heating or cooling can cause lattice distortion, affecting the structural stability of the target material and the quality of subsequent coatings. Therefore, by first heating to thoroughly degas and then slowly cooling in steps, the Al target material can gradually release the internal adsorbed gases while simultaneously releasing thermal stress, ensuring the uniformity of its microstructure. Oxygen-free copper targets, on the other hand, have excellent high-temperature performance and a low coefficient of thermal expansion, requiring no complex cooling process; direct heating and degassing is sufficient.

[0050] Understandably, the degassing temperature process can be designed for other targets that require vacuum high-temperature degassing, based on their material properties, so it will not be elaborated further.

[0051] S2: On the surface of an oxygen-free copper target, a first zirconium film, a high-entropy ceramic tritium barrier layer, and a second zirconium film are sequentially deposited using a magnetron sputtering process to form a polycrystalline film layer.

[0052] like Figure 6 As shown, Figure 6 This is a flowchart of step S2 in the pre-fabricated tritium target manufacturing method based on polycrystalline film provided in the embodiments of the present invention.

[0053] S2 includes: S2.1: Place the first set of sputtering targets, heat the oxygen-free copper target substrate to 400℃ to 450℃, and maintain the vacuum level in the cavity at 2×10⁻⁶. - ¹Pa to 3×10 - Between ¹Pa, a magnetron sputtering process is used, with pre-sputtering for 10 to 15 minutes at a sputtering power of 120W to 480W; S2.2: The first metallic zirconium film is formed by sputtering at a sputtering power of 120W to 480W for 30 to 50 minutes using a magnetron sputtering process. For example, the first set of sputtering targets uses zirconium (Zr) targets. In order to ensure the compactness and stability of the first metallic zirconium film, the metal purity of zirconium in the first set of sputtering targets is not less than 99.99%.

[0054] S2.3: The oxygen-free copper target substrate coated with the first metallic zirconium film is placed in a high-vacuum degassing furnace and subjected to high-temperature curing treatment at 850°C. S2.4: Place the second set of sputtering targets, and after vacuum high-temperature degassing of the oxygen-free copper target substrate coated with the first zirconium film, heat it again to 400℃ to 450℃, maintaining the vacuum level in the cavity at 2×10⁻⁶. - ¹Pa to 3×10 - Between ¹Pa, pre-sputtering is performed using magnetron sputtering process for 5 to 10 minutes; In an optional implementation, in S2, when a high-entropy ceramic tritium barrier layer is deposited using a magnetron sputtering process, the second set of sputtering targets are made of five metal elements: Al, Cr, Ta, Ti, and Zr, respectively, and magnetron sputtering is performed in a mixed atmosphere of nitrogen and argon. In this process, the purity of each individual sputtering target is no less than 99.99% for a single metal; the volume percentage of nitrogen in the mixed atmosphere is 20%, and the purity of both nitrogen and argon is no less than 99.99%. This ensures that the purity of nitrogen prevents the introduction of impurities, thus avoiding contamination of the tritium barrier layer in subsequent processes; and ensures the purity of argon, preventing instability in the generated plasma gas and avoiding issues such as sparking and target contamination.

[0055] S2.5: A high-entropy ceramic tritium barrier layer is deposited in a mixed atmosphere of nitrogen and argon using magnetron sputtering at a sputtering power of 480W. S2.6: Insert the third set of sputtering targets, maintaining a vacuum level of 2×10⁻⁶ within the cavity. - ¹Pa to 3×10 -Between ¹Pa, a magnetron sputtering process is used, with pre-sputtering for 10 to 15 minutes at a sputtering power of 120W to 480W; S2.7: Using magnetron sputtering, a second metallic zirconium film is deposited by sputtering at a sputtering power of 120W to 480W for 30 to 50 minutes to obtain a polycrystalline film layer.

[0056] For example, the third set of sputtering targets uses zirconium (Zr) targets. In order to ensure the compactness and stability of the second metallic zirconium film, the metal purity of zirconium in the third set of sputtering targets is not less than 99.99%.

[0057] To enable those skilled in the art to fully understand and implement the present invention, the specific implementation principle of this embodiment S2 is further explained below in conjunction with a specific application scenario.

[0058] like Figure 7 As shown, Figure 7 This is a process flow diagram of the pre-fabricated tritium target manufacturing method based on polycrystalline film provided in the embodiments of the present invention.

[0059] Since the ductility of the first metallic zirconium film is higher than that of the high-entropy ceramic tritium barrier layer and lower than that of the oxygen-free copper target substrate, it can protect the ceramic film formed by the high-entropy ceramic tritium barrier layer. If the high-entropy ceramic is directly deposited on the surface of the oxygen-free copper target substrate, the difference in ductility between the two will damage the high-entropy ceramic film when the oxygen-free copper target substrate is in a high-temperature working state, causing it to lose its tritium barrier function.

[0060] Based on this, in order to ensure the quality of the first zirconium metal film, the thickness of the first zirconium metal film can be maintained between 3μm and 5μm. At this time, the thickness of the first zirconium metal film can be calculated by weighing. First, the oxygen-free copper target substrate to be coated is marked. Then, a high-precision electronic balance with a measurement accuracy of 0.01mg is selected. Before the formal measurement, the balance is preheated for at least 0.5h. After calibration, the weight is weighed. Each oxygen-free copper target substrate is weighed 6 times, and the average value is taken to obtain and record the weight before coating.

[0061] The weighed oxygen-free copper target is fixed on the coating fixture. The distance between the target surface of the oxygen-free copper target and the zirconium target used for magnetron sputtering is determined. This distance can be set between 30mm and 100mm. The principle is that if the distance is too close, the zirconium metal ion sputtering will be too fast, affecting the density of the zirconium film and easily causing the transition layer to peel off. If the distance is too far, the coating efficiency will be greatly reduced, resulting in waste of zirconium metal. Therefore, preferably, the distance between the target surface of the oxygen-free copper target and the zirconium target used for magnetron sputtering is set to 50mm.

[0062] Adjust the equipment settings and evacuate until the vacuum level reaches 5×10⁻⁶. -5After Pa, heating is turned on and a secondary vacuum high-temperature degassing treatment is performed. This is because when handling oxygen-free copper target base and metallic zirconium target material, the target base or target material will inevitably be exposed to the external environment, so a secondary vacuum high-temperature degassing treatment is required.

[0063] Optionally, during the heating process, the high temperature can accelerate the movement of ions, making the deposited film layer more dense; since it is a secondary vacuum high-temperature degassing process, the degassing temperature needs to be compatible with the coating temperature, and the temperature can be set to 450℃.

[0064] For example, the degassing temperature process is shown in Table 3.

[0065] Table 3. Degassing temperature process of secondary vacuum high-temperature degassing treatment

[0066] Before the formal magnetron sputtering coating, the oxygen-free copper target substrate and the corresponding sputtering target material mounted on the coating fixture undergo a secondary vacuum high-temperature degassing treatment. This treatment employs a stepped heating and cooling process, specifically as follows: At a vacuum level of 5×10⁻⁶... -5 After Pa, heating begins. First, the temperature is raised from room temperature to 200°C, a process that takes 40 minutes. Then, the temperature is raised to 350°C, a process that takes 30 minutes, and held at 350°C for 10 minutes. Next, the temperature is raised to 400°C, a process that takes 40 minutes, and held at 400°C for 40 minutes. Finally, the temperature is raised to 450°C, a process that takes 40 minutes, and held at 450°C for an extended period of 360 minutes. The longer holding time at 450°C is necessary for two reasons: first, the need for vacuum high-temperature degassing to thoroughly remove gases re-adsorbed from atmospheric exposure; and second, to allow sufficient time for coating. If the coating process is completed during this period, cooling can be initiated earlier. After coating, the temperature is lowered from 450°C to 200°C, a cooling process that takes 60 minutes, followed by a brief holding at 200°C and then natural cooling to room temperature. The secondary vacuum high-temperature degassing process can further purify the surface of the substrate and the target material, ensuring the formation of a dense and well-bonded film.

[0067] During the constant temperature process, the equipment vacuum level was displayed as below 5×10. -5 At a pressure of 550V, pre-sputtering can be performed. At this time, the deflection voltage is set to 550V, and high-purity argon gas (the purity of the argon gas alone is not less than 99.99%) is introduced. The solenoid valve is opened to 10%, and the flow rate of the argon gas is controlled by the pressure reducing valve to maintain the vacuum level in the chamber at 2 × 10⁻⁶ Pa. - ¹Pa to 3×10 - Between ¹Pa, the preset duration is 10 minutes, and the pre-sputtering power is 120W.

[0068] Pre-sputtering can further eliminate impurities on the surface of zirconium metal, ensuring the coating effect. During this process, the operation of the equipment can be observed through the observation window on the magnetron sputtering equipment.

[0069] After pre-sputtering is completed, the first zirconium metal film can be deposited. At this time, open the baffle valve on the magnetron sputtering equipment, and simultaneously turn on the workpiece rotation and revolution functions, increase the sputtering power to 480W, adjust the sputtering coating time to 30min, and keep other parameters unchanged.

[0070] Once the equipment temperature has cooled to room temperature, the oxygen-free copper target substrate after coating is removed and weighed. The weight and thickness of the film are determined based on the weight difference before and after coating. If the thickness is insufficient, the coating needs to be removed, and the coating time parameters adjusted until the requirements are met. Afterward, the oxygen-free copper target substrate coated with the first zirconium film is placed in a high-vacuum degassing furnace and cured at 850°C. This high-temperature curing process also serves to verify the quality and thickness of the coating.

[0071] Specifically, if the coating has defects such as poor adhesion, microcracks, or severely uneven thickness, the film is prone to localized peeling, blistering, or abnormal color changes under high-temperature thermal stress, thus exposing potential quality problems. Furthermore, by measuring the weight change of the sample before and after high-temperature curing, the uniformity of the coating thickness and the consistency of the process can also be assessed. At the same time, high-temperature curing also helps stabilize the film structure and improve its bonding strength with the oxygen-free copper target substrate.

[0072] The process of depositing a high-entropy ceramic tritium barrier layer is similar to that of depositing a first metal zirconium film. In this case, the target material needs to be replaced by five metals: Al, Cr, Ta, Ti, and Zr, and the high-purity argon gas needs to be replaced by a mixture of high-purity nitrogen and high-purity argon gas. The ratio of the mixed gas is argon:nitrogen = 8:2.

[0073] Similarly, before coating, the oxygen-free copper target substrate coated with the first zirconium film is weighed and then fixed on the coating fixture. The coating distance is set, and then the targets (Al, Cr, Ta, Ti, Zr) are placed in their respective positions in sequence. After vacuuming to the required standard, the substrate is heated. Once the constant temperature and vacuum parameters meet the requirements, pre-sputtering begins for 5 minutes. After pre-sputtering, the high-entropy ceramic tritium barrier layer is formally coated for 30 minutes. The coating process of the high-entropy ceramic tritium barrier layer adopts a five-element co-sputtering process, that is, five metal targets (Al, Cr, Ta, Ti, Zr) are sputtered simultaneously, and their particles are deposited together on the oxygen-free copper target to form a high-entropy ceramic layer.

[0074] After the coating process is complete and the magnetron sputtering equipment temperature returns to room temperature, the oxygen-free copper target is removed, and the weight and thickness of the coating are determined by a second weighing. Compared with simple metal nitride ceramics, the high-entropy ceramic tritium barrier layer made of pentaceous nitride ceramics has excellent tritium barrier performance and excellent high-temperature resistance, maintaining stable tritium barrier performance at 1000℃.

[0075] Similarly, the deposition and inspection process for the second zirconium film is similar to that of the first zirconium film or the high-entropy ceramic tritium barrier layer. The deposition thickness ranges from 3 μm to 5 μm, and the film is weighed three times after deposition. Using zirconium as the sputtering target, compared to traditional titanium films, the zirconium film exhibits better high-temperature stability and higher film density. Under the same deposition process, the density of the zirconium film is 20% higher than that of the titanium film.

[0076] S3: The oxygen-free copper target substrate coated with a polycrystalline film is purged with tritium to allow tritium to combine with the second metallic zirconium film, forming a zirconium tritide layer.

[0077] In S3, the tritium filling process adopts a stepped cooling tritium filling process, which includes: filling tritium gas at a constant temperature of 500℃ to 550℃, gradually cooling down in a cooling step of 50℃ to 100℃, maintaining a constant temperature for each cooling step for 30 to 40 minutes, until the temperature drops to 200℃ to 250℃, then recovering the tritium gas in the chamber and allowing it to cool naturally to room temperature.

[0078] Specifically, an oxygen-free copper target substrate coated with a polycrystalline film is fixed in the appropriate position and heated to 550°C. The tritium filling equipment is then evacuated and heated until a constant temperature is reached. The oxygen-free copper target substrate coated with the polycrystalline film is then filled with tritium. First, tritium gas is introduced into the tritium filling chamber of the magnetron sputtering equipment at a certain flow rate. Then, a cooling curve is set, with each step being 50°C, and each step is held constant for 30 minutes until the temperature drops to 250°C, at which point the process ends. Finally, the tritium gas in the chamber is recovered, the heating is turned off, and the magnetron sputtering equipment is allowed to cool naturally to room temperature. The pre-fabricated tritium target is then removed and placed in an isolation chamber. Four weighings are performed using an electronic balance inside the isolation chamber. Based on the weight before and after tritium filling, the mass of tritium filling is calculated, and the tritium-zirconium ratio is further obtained, ensuring that the tritium-zirconium ratio is not less than 1.6:1.

[0079] S4: The oxygen-free copper target substrate with the zirconium tritide layer is bonded to the oxygen-free copper target holder by brazing, thus completing the manufacturing of the pre-made tritium target.

[0080] It is worth noting that the pre-fabricated tritium target manufacturing method based on polycrystalline films of the present invention, through process steps including pretreatment and multilayer magnetron sputtering coating, ensures high-quality preparation of pre-fabricated tritium targets based on polycrystalline films. Specifically, the pretreatment and degassing processes provide a clean and stable substrate interface for film bonding; a first zirconium film as a transition layer, a high-entropy ceramic tritium barrier layer, and a second zirconium film as a tritium filling layer are sequentially deposited to construct a functionally distinct polycrystalline film structure. Furthermore, the step-cooling tritium filling process optimizes the diffusion and bonding process of tritium in the surface zirconium film, promotes the formation of a highly stable zirconium tritide layer, ensures the stability of the pre-fabricated tritium target under high-temperature conditions, and improves the service life of the neutron tube.

[0081] It should be noted that the magnetron sputtering process and other technologies used in the preparation of the pre-fabricated tritium target in this embodiment are all existing mature technologies, and the relevant parameter settings can be implemented with reference to existing related technologies.

[0082] The preparation method provided in Embodiment 2 of the present invention can be used to prepare the pre-fabricated tritium target based on a polycrystalline film provided in Embodiment 1, and therefore has similar beneficial effects to the device embodiment in Embodiment 1. For technical details not disclosed in the embodiments of the preparation method of the present invention, please refer to the description of the device embodiment for understanding.

[0083] Example 3 To further verify the advantages of the pre-fabricated tritium target based on polycrystalline film of the present invention in balancing heat dissipation and tritium blocking performance, this embodiment sets up two comparative structures, corresponding to two common pre-fabricated tritium target structures: one is to use pure metallic molybdenum as the target substrate, and then fill it with tritium after coating its surface with a titanium film to form a tritium-titanium target; the other is to use metallic oxygen-free copper as the target substrate, and then fill it with tritium after coating it with a titanium film.

[0084] It should be noted that in the field of tritium target technology, heat dissipation performance is mainly characterized by the thermal conductivity of the target substrate material and the temperature rise of the target surface, while tritium blocking performance is mainly characterized by the tritium retention rate. The following comparative examples all use the same oxygen-free copper target substrate size, the same magnetron sputtering process parameters, and the same tritium filling process conditions as in Example 1 to ensure the scientific validity of the comparison.

[0085] In prefabricated tritium targets, achieving both efficient heat dissipation and effective tritium blocking is challenging. Heat dissipation capacity primarily depends on the thermal conductivity of the target substrate material: oxygen-free copper has a thermal conductivity of approximately 390 W / (m·K), while pure molybdenum has a thermal conductivity of approximately 138 W / (m·K), indicating that copper substrates offer significantly better heat dissipation than molybdenum substrates. However, oxygen-free copper itself has extremely high permeability to tritium isotopes, providing almost no tritium blocking capability; while molybdenum, although having poor thermal conductivity, possesses a dense lattice structure that provides some physical barrier effect against tritium. Both copper-based and molybdenum-based titanium-coated solutions rely on the surface titanium film as a tritium reservoir layer. However, titanium films are prone to microscopic defects at high temperatures, and the thermal expansion coefficients of the titanium film and the substrate material are mismatched, easily leading to stress damage during thermal cycling. Therefore, existing solutions struggle to simultaneously achieve efficient heat dissipation and long-term tritium blocking. The following verification is conducted using Comparative Examples 1 and 2, and compared with the embodiments of this invention.

[0086] Comparative Example 1: Pure metallic molybdenum with a purity of ≥99.95% was used as the target substrate. A titanium film with a thickness of 5μm was deposited on the substrate by magnetron sputtering. The deposition process parameters were the same as those for the zirconium film in Example 1. After being filled with tritium, the titanium film was converted into a titanium tritide layer to form a pre-made tritium target.

[0087] The performance of the pre-fabricated tritium target of Comparative Example 1 was tested, and the results are as follows: the thermal conductivity of the target substrate is 138 W / (m·K); under continuous deuterium ion beam bombardment with a beam current density of 10 mA / cm² and an energy of 120 keV, the steady-state temperature rise of the target surface is 180 °C; the initial tritium-to-titanium atomic ratio is 1.5:1; after being kept at 300 °C for 24 h, the tritium retention rate is about 82%; after thermal cycling from room temperature to 500 °C for 10 cycles, slight oxidation and microcracks appear on the surface of the titanium film, and the tritium retention rate decreases to 65%.

[0088] Comparative Example 2: Oxygen-free copper with a purity of ≥99.998% was used as the target substrate. A titanium film with a thickness of 5μm was deposited on the substrate by magnetron sputtering. The deposition and tritium filling process was the same as that of Comparative Example 1. After tritium filling, a titanium tritide layer was formed, and a pre-made tritium target was obtained.

[0089] The performance of the pre-fabricated tritium target of Comparative Example 2 was tested, and the results are as follows: the thermal conductivity of the target substrate is 390 W / (m·K); under the same deuterium ion beam bombardment conditions as Comparative Example 1, the steady-state temperature rise of the target surface is 95℃, and the heat dissipation performance is significantly better than that of Comparative Example 1; the initial tritium-to-titanium atomic ratio is approximately 1.5:1; after being kept at a constant temperature of 300℃ for 24 hours, due to the almost non-blocking effect of the copper substrate on tritium, a large amount of tritium is lost through the substrate, and the tritium retention rate is approximately 75%; after 10 cycles from room temperature to 500℃, the titanium film shows local peeling, and the tritium retention rate decreases to 52%.

[0090] The pre-fabricated tritium target (first zirconium film / high-entropy ceramic tritium barrier layer / second zirconium film, with a tritium-to-zirconium atomic ratio ≥1.6:1 after tritium filling) prepared in Example 1 of this invention was compared with the comparative example, and the results are as follows: The target substrate of this invention has a thermal conductivity of 390 W / (m·K). Under continuous deuterium ion beam bombardment under the same conditions, the steady-state temperature rise of the target surface is 95℃~100℃, which is comparable to the heat dissipation performance of Comparative Example 2 and significantly better than Comparative Example 1. After being held at a constant temperature of 300℃ for 24 hours, the tritium retention rate is ≥95%. After thermal cycling from room temperature to 500℃ for 10 cycles, the three-layer film structure remains intact without cracking or peeling, and the tritium retention rate is still ≥90%. Under continuous bombardment for 100 hours, the neutron yield decay rate is <5%.

[0091] The comparative results show that, in terms of heat dissipation performance, the target surface temperature rise of Comparative Example 2 (using an oxygen-free copper target substrate) and the embodiment of the present invention is only about half that of Comparative Example 1, demonstrating superior heat dissipation performance. This indicates that the present invention maintains excellent heat dissipation capabilities without sacrificing tritium blocking performance. Regarding tritium blocking performance, while Comparative Example 1 exhibits some tritium blocking capability, its poor thermal conductivity of the molybdenum substrate makes the titanium film susceptible to damage at high temperatures. Comparative Example 2, due to the lack of tritium blocking capability of the copper substrate, has the lowest tritium retention rate. The present invention, by introducing a high-entropy ceramic tritium blocking layer, forms a highly efficient tritium permeation barrier between the copper substrate and the tritium storage layer, increasing the tritium retention rate at a constant temperature of 300℃ to over 95%, and maintaining over 90% after thermal cycling, far superior to the comparative examples.

[0092] The performance comparison above shows that neither of the two ratios can simultaneously achieve efficient heat dissipation and long-term tritium blocking. The pre-fabricated tritium target of this invention, through a polycrystalline film composed of a first zirconium film, a high-entropy ceramic tritium blocking layer, and a second zirconium film, maintains the excellent heat dissipation performance of oxygen-free copper while increasing the high-temperature tritium retention rate to over 95%, and its thermal cycling stability is significantly better than existing solutions. This allows the prepared pre-fabricated tritium target to be reused, improving its utilization rate and reducing the cost of using neutron tubes.

[0093] It should be noted that, in this document, relational terms such as "first" and "second" 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 are intended to cover non-exclusive inclusion, such that an article or device comprising a list of elements includes not only those elements but also other elements not expressly listed. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device comprising said element. Terms such as "connected" or "linked" are not limited to physical or mechanical connections but can include electrical connections, whether direct or indirect. The orientations or positional relationships indicated by terms such as "upper," "lower," "left," and "right" are based on the orientations or positional relationships shown in the accompanying drawings and are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention.

[0094] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A pre-fabricated tritium target based on a polycrystalline film, characterized in that, include: Oxygen-free copper target; A polycrystalline film is deposited on the first surface of the oxygen-free copper target substrate; The polycrystalline film layer comprises: a first zirconium metal film, a high-entropy ceramic tritium barrier layer, and a second zirconium metal film, which are sequentially deposited from the inside to the outside; An oxygen-free copper target holder is fixed to the second surface of the oxygen-free copper target base; The oxygen-free copper target substrate provides the main heat dissipation path, the first zirconium metal film forms an ductile transition layer to buffer the thermal stress between the oxygen-free copper target substrate and the high-entropy ceramic tritium barrier layer, the high-entropy ceramic tritium barrier layer provides a tritium barrier, and the second zirconium metal film, as a tritium-filled layer, combines with tritium to form a zirconium tritide layer.

2. The pre-fabricated tritium target based on a polycrystalline film according to claim 1, characterized in that, The high-entropy ceramic tritium barrier layer is a pentagonal nitride ceramic with the chemical formula (AlCrTaTiZr)N.

3. The pre-fabricated tritium target based on a polycrystalline film according to claim 1, characterized in that, The first zirconium film, the high-entropy ceramic tritium barrier layer, and the second zirconium film have the same thickness, ranging from 3 μm to 5 μm.

4. The pre-fabricated tritium target based on a polycrystalline film according to claim 1, characterized in that, In the tritium-filled zirconium tritide layer formed by the second zirconium metal film, the atomic ratio of tritium to zirconium is not less than 1.6:

1.

5. The pre-fabricated tritium target based on a polycrystalline film according to claim 1, characterized in that, The first surface of the oxygen-free copper target substrate is concave, and the first zirconium metal film, the high-entropy ceramic tritium barrier layer, and the second zirconium metal film are sequentially deposited on the concave surface of the oxygen-free copper target substrate. The second surface of the oxygen-free copper target base is disposed opposite to the first surface, and the second surface of the oxygen-free copper target base is bonded to the oxygen-free copper target holder by brazing; the oxygen-free copper target holder is sealed to the neutron tube shell by argon arc welding.

6. A method for manufacturing a pre-tritium target based on a polycrystalline film, used to prepare a pre-tritium target based on a polycrystalline film as described in any one of claims 1 to 5, characterized in that, The methods include: S1: Prepare oxygen-free copper target substrate and pretreat tritium target components; S2: On the surface of the oxygen-free copper target substrate, a first zirconium film, a high-entropy ceramic tritium barrier layer and a second zirconium film are sequentially deposited using a magnetron sputtering process to form a polycrystalline film layer. S3: The oxygen-free copper target substrate coated with the polycrystalline film is subjected to tritium purging treatment, so that tritium combines with the second metallic zirconium film to form a zirconium tritide layer; S4: The oxygen-free copper target substrate with the zirconium tritide layer is bonded to the oxygen-free copper target holder by brazing, thus completing the manufacturing of the pre-made tritium target.

7. The method for manufacturing a pre-tritium target based on a polycrystalline film according to claim 6, characterized in that, In S1, the pretreatment of the tritium target component includes: sequentially performing degreasing, pickling, neutralization, dehydration and vacuum high-temperature degassing treatment on the oxygen-free copper target substrate; The vacuum high-temperature degassing process includes: sequentially heating the oxygen-free copper target substrate from room temperature to various preset temperatures in a vacuum environment, and maintaining the temperature at each preset temperature. Each preset temperature is between room temperature and 850°C and increases sequentially in steps. The preset temperatures are room temperature, 200°C, 400°C, 450°C, 700°C and 850°C.

8. The method for manufacturing a pre-tritium target based on a polycrystalline film according to claim 7, characterized in that, S2 include: S2.1: Place the first set of sputtering targets, heat the oxygen-free copper target substrate to 400°C to 450°C, and maintain the vacuum level in the cavity at 2×10⁻⁶. - ¹Pa to 3×10 - Between ¹Pa, a magnetron sputtering process is used, with pre-sputtering for 10 to 15 minutes at a sputtering power of 120W to 480W; S2.2: The first metallic zirconium film is formed by sputtering at a sputtering power of 120W to 480W for 30 to 50 minutes using a magnetron sputtering process. S2.3: The oxygen-free copper target substrate coated with the first metal zirconium film is placed in a high vacuum degassing furnace and subjected to high-temperature curing treatment at 850°C. S2.4: Place the second set of sputtering targets, and after vacuum high-temperature degassing of the oxygen-free copper target substrate coated with the first zirconium film, heat it again to 400℃ to 450℃, maintaining the vacuum level in the cavity at 2×10⁻⁶. - ¹Pa to 3×10 - Between ¹Pa, pre-sputtering is performed using magnetron sputtering process for 5 to 10 minutes; S2.5: A high-entropy ceramic tritium barrier layer is deposited in a mixed atmosphere of nitrogen and argon using magnetron sputtering at a sputtering power of 480W. S2.6: Insert the third set of sputtering targets, maintaining a vacuum level of 2×10⁻⁶ within the cavity. - ¹Pa to 3×10 - Between ¹Pa, a magnetron sputtering process is used, with pre-sputtering for 10 to 15 minutes at a sputtering power of 120W to 480W; S2.7: Using magnetron sputtering, a second metallic zirconium film is deposited by sputtering at a sputtering power of 120W to 480W for 30 to 50 minutes to obtain a polycrystalline film layer.

9. The method for manufacturing a pre-tritium target based on a polycrystalline film according to claim 8, characterized in that, In S2, when the high-entropy ceramic tritium barrier layer is deposited using magnetron sputtering, independent sputtering targets made of five metal elements, namely Al, Cr, Ta, Ti and Zr, are used, and magnetron sputtering is performed in a mixed atmosphere of nitrogen and argon. The purity of each individual sputtering target is not less than 99.99% for a single metal; the volume percentage of nitrogen in the mixed atmosphere is 20%, and the purity of both nitrogen and argon is not less than 99.99% for a single gas.

10. The method for manufacturing a pre-tritium target based on a polycrystalline film according to claim 6, characterized in that, In S3, the tritium filling process adopts a stepped cooling tritium filling process, including: filling tritium gas at a constant temperature of 500°C to 550°C, gradually cooling down in a cooling step of 50°C to 100°C, maintaining the temperature at each cooling step for 30 to 40 minutes, until the temperature drops to 200°C to 250°C, then recovering the tritium gas in the cavity and allowing it to cool naturally to room temperature.

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