Vacuum film window structure and processing method

Abstract

The present application relates to the technical field of particle therapy, and provides a vacuum film window structure and a processing method.The structure comprises a film window flange, a support mesh, a non-metallic polymer film, a film window pressing plate, a first sealing element and a second sealing element.The film window flange is provided with an annular positioning portion.The support mesh is arranged on the annular positioning portion.The non-metallic polymer film is arranged on one side of the support mesh away from the annular positioning portion, and the non-metallic polymer film is plated with a metal layer.The film window pressing plate is arranged on one side of the non-metallic polymer film away from the support mesh.The first sealing element is arranged between the periphery of the support mesh and the non-metallic polymer film, and the second sealing element is arranged between the periphery of the annular positioning portion and the periphery of the non-metallic polymer film.The non-metallic polymer film, the film plating layer and the support mesh are tightly adhered together, so that the film thickness is greatly reduced, the vacuum performance of the single-layer film is better than that of the existing double-layer structure, the energy loss, scattering and neutron yield when the beam passes through the film are reduced, and the beam quality and treatment accuracy are improved.

Description

Technical Field

[0001] This invention relates to the field of particle therapy technology, and in particular to a vacuum membrane window structure and its processing method. Background Technology

[0002] In recent years, with the rise in global cancer incidence, especially with the arrival of an aging society, the demand for highly effective cancer treatments has been increasing. Particle therapy devices, as large-scale medical devices for precision treatment, have seen rapid development. Particle therapy devices require extracting high-energy particle beams generated by accelerators to the treatment point. Currently, the mainstream beam extraction methods include membrane windows, differential beams, and plasma windows. However, in clinical treatment, the beam needs to be broadened to a larger physical cross-section through a scanning magnet system, resulting in a significant increase in the required beam extraction size. Against this backdrop, differential beams are too large and expensive, and plasma windows, with extraction sizes limited to approximately Φ10 mm, are insufficient to meet the clinical requirements for large-size beams. Therefore, membrane windows have become a feasible solution for achieving large-size beam extraction.

[0003] Currently, the treatment chamber window of the new generation of particle therapy devices has increased in size to a square of 270 mm × 270 mm. Existing treatment devices require a significant increase in the thickness of the membrane window to ensure mechanical strength to withstand atmospheric pressure and isolate the vacuum system from the atmospheric environment. This thick membrane window causes severe interactions when high-energy particle beams pass through, resulting in significant energy loss, scattering, and neutron yield, directly affecting beam quality and treatment precision. At the same time, the huge energy deposited on the thick membrane triggers significant thermal deposition effects and radiation damage, posing a serious threat to the long-term stable operation of the membrane window itself and the entire vacuum system.

[0004] Furthermore, the permeation rate of the membrane window increases significantly with the increase in the extraction size. Even with a double-layer structure, existing treatment devices still require evacuation and layered vacuuming to reduce permeation in order to barely maintain a vacuum level of 10 in the surrounding area. -7 The mbar level not only doubles the overall membrane thickness, but also causes gases with high surface adsorption energy, such as water from the air, or those that cannot be adsorbed by the ion pump, to accumulate on the inner surface of the vacuum system near the membrane window over time. This leads to a slow decrease in vacuum, which may even exceed the normal operating limit of the ion pump, causing the ion pump to shut down for protection, thereby affecting beam quality and treatment precision. Summary of the Invention

[0005] This invention provides a vacuum membrane window structure and processing method to solve the defects of existing technologies, such as excessive membrane thickness and excessive membrane permeability, which lead to insufficient beam quality and treatment precision.

[0006] This invention provides a vacuum membrane window structure, comprising:

[0007] A membrane window flange, wherein an annular positioning part is provided on one side of the membrane window flange;

[0008] A supporting mesh is disposed in the annular positioning part, and the periphery of the supporting mesh is located inside the periphery of the annular positioning part;

[0009] A non-metallic polymer film is disposed on the side of the support mesh opposite to the annular positioning part, the periphery of the non-metallic polymer film extends to the outside of the support mesh, and the surface of the non-metallic polymer film is coated with a metal layer.

[0010] A sealing assembly includes a first sealing element and a second sealing element. The first sealing element is disposed between the periphery of the supporting mesh and the non-metallic polymer film, and the second sealing element is disposed between the periphery of the annular positioning portion and the periphery of the non-metallic polymer film. The first sealing element includes four first sealing wires, which are respectively disposed in the four straight-edge regions of the annular positioning portion. Both ends of each first sealing wire extend to the outer side of the membrane window pressure plate and are connected to the outer peripheral side of the annular positioning portion or the outer peripheral side of the membrane window pressure plate by a first fastener, which is used to apply a pre-tightening force to the first sealing wire. The second sealing element includes four second sealing wires, which are respectively disposed in the four straight-edge regions of the annular positioning portion and are located outside the first sealing wires. Both ends of each second sealing wire extend to the outer side of the membrane window pressure plate and are connected to the outer peripheral side of the annular positioning portion or the outer peripheral side of the membrane window pressure plate by a second fastener, which is used to apply a pre-tightening force to the second sealing wire.

[0011] A membrane window pressure plate is disposed on the side of the non-metallic polymer film away from the supporting mesh and is fastened to the membrane window flange, so that the first sealing member presses the supporting mesh against the annular positioning part, and the second sealing member seals the periphery of the annular positioning part and the periphery of the non-metallic polymer film.

[0012] According to a vacuum membrane window structure provided by the present invention, the annular positioning part is an annular boss that protrudes axially from the end face of the membrane window flange, and the cross-section of the annular boss is quadrilateral.

[0013] According to a vacuum membrane window structure provided by the present invention, the first fastener is a connecting bolt connected to the outer periphery of the annular positioning part.

[0014] According to a vacuum membrane window structure provided by the present invention, the second fastener is a connecting bolt connected to the outer periphery of the annular positioning part.

[0015] According to the vacuum membrane window structure provided by the present invention, the first sealing wire is a sealing aluminum wire or a sealing silver wire, and / or,

[0016] The second sealing wire is a sealing aluminum wire or a sealing silver wire.

[0017] According to the present invention, a vacuum membrane window structure is provided, wherein the non-metallic polymer film is a Hostaphan film.

[0018] According to a vacuum membrane window structure provided by the present invention, the thickness of the non-metallic polymer film is 10μm to 75μm.

[0019] According to the present invention, a vacuum membrane window structure is provided, wherein the metal layer is an aluminum layer with a thickness of 1μm to 5μm.

[0020] According to a vacuum membrane window structure provided by the present invention, the annular positioning part is provided with rounded corners.

[0021] The present invention also provides a method for processing a vacuum membrane window structure, comprising:

[0022] Prepare a membrane window flange, a membrane window pressure plate, a first sealing element, and a second sealing element, and machine an annular positioning part on the membrane window flange;

[0023] The non-metallic polymer film, the membrane window flange, the membrane window pressure plate, the first seal and the second seal are cleaned.

[0024] The membrane window flange, the membrane window pressure plate, the first seal and the second seal are vacuum degassed after cleaning;

[0025] Metal is plated onto the surface of the cleaned non-metallic polymer film to form a metal layer on the surface of the non-metallic polymer film; the first sealing member includes four first sealing wires, which are respectively disposed in the four straight-edge areas of the annular positioning part; both ends of each first sealing wire extend to the outside of the membrane window pressure plate and are connected to the outer peripheral side of the annular positioning part or the outer peripheral side of the membrane window pressure plate by a first fastener, which is used to apply a pre-tightening force to the first sealing wire; the second sealing member includes four second sealing wires, which are respectively disposed in the four straight-edge areas of the annular positioning part and are located outside the first sealing wires; both ends of each second sealing wire extend to the outside of the membrane window pressure plate and are connected to the outer peripheral side of the annular positioning part or the outer peripheral side of the membrane window pressure plate by a second fastener, which is used to apply a pre-tightening force to the second sealing wire;

[0026] The membrane window flange, the support liner, the non-metallic polymer film, and the membrane window pressure plate are assembled in sequence, and the first sealing member is placed between the periphery of the support liner and the non-metallic polymer film, and the second sealing member is placed between the periphery of the annular positioning part and the periphery of the non-metallic polymer film.

[0027] The membrane window flange and the membrane window pressure plate are pressed together so that the first sealing member presses the support mesh against the annular positioning part, and the second sealing member seals the area between the periphery of the annular positioning part and the periphery of the non-metallic polymer film.

[0028] The vacuum membrane window structure provided by this invention features an annular positioning part on the membrane window flange, upon which a supporting mesh and a non-metallic polymer film coated with a metal layer are sequentially arranged. By tightly bonding the non-metallic polymer film, the metal layer coated on the film, and the supporting mesh together, the membrane thickness is significantly reduced, thereby reducing energy loss, scattering, and neutron yield when high-energy particle beams penetrate the membrane, improving beam quality and treatment precision. Furthermore, the metal layer enhances the gas barrier performance, thermal conductivity, and radiation damage resistance of the membrane window, effectively increasing the vacuum level, mitigating the thermal deposition effect, and enhancing radiation damage lifetime. Furthermore, the plated metal layer acts as a high-barrier barrier against gas, effectively suppressing gas permeation from non-metallic materials, enabling a single-layer non-metallic polymer film to achieve excellent vacuum sealing performance. Additionally, the periphery of the support mesh is confined to the inner side of the annular positioning section, while the periphery of the non-metallic polymer film extends outwards and covers the support mesh. When the membrane window flange and membrane window pressure plate are pressed together, the first sealing element is clamped between the edge of the support mesh and the non-metallic polymer film, firmly fixing the support mesh to the annular positioning section. This provides uniform and reliable reinforcement for the non-metallic polymer film, significantly reducing film thickness and minimizing the adverse effects caused by beam-membrane interaction. Simultaneously, a second sealing element is provided between the outer edge of the annular positioning section and the edge of the non-metallic polymer film, forming a reliable peripheral vacuum sealing interface, allowing the membrane window area to maintain a stable 10°C for a long period. -9 Ultra-high vacuum in the mbar range. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0030] Figure 1 This is an exploded view of the vacuum membrane window structure provided by the present invention.

[0031] Figure 2This is a side view of the vacuum membrane window structure provided by the present invention.

[0032] Figure 3 This is a schematic diagram of the structure of the sealing component provided by the present invention.

[0033] Figure 4 This is a schematic diagram of the structure of the second sealing element provided by the present invention.

[0034] Figure label:

[0035] 100. Membrane window flange; 110. Annular positioning part; 200. Supporting liner;

[0036] 300, Sealing assembly; 310, First seal; 311, First sealing thread; 312, First fastener; 320, Second seal; 321, Second sealing thread; 322, Second fastener;

[0037] 400. Non-metallic polymer film; 500. Membrane window pressure plate. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0039] In the description of the embodiments of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0040] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention based on the specific circumstances.

[0041] In embodiments of the present invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0042] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0043] The following is combined Figures 1-4 The vacuum membrane window structure of the present invention is described.

[0044] An embodiment of the first aspect of the present invention provides a vacuum membrane window structure, such as Figures 1 to 4 As shown, the vacuum membrane window structure includes a membrane window flange 100, a support mesh 200, a non-metallic polymer film 400, a membrane window pressure plate 500, and a sealing assembly 300.

[0045] The membrane window flange 100 has an annular positioning portion 110 on one side; a support mesh 200 is disposed on the annular positioning portion 110, with the periphery of the support mesh 200 located inside the periphery of the annular positioning portion 110; a non-metallic polymer film 400 is disposed on the side of the support mesh 200 away from the annular positioning portion 110, with the periphery of the non-metallic polymer film 400 extending to the outside of the support mesh 200, and the surface of the non-metallic polymer film 400 is coated with a metal layer; the sealing assembly 300 includes a first sealing element 310 and a second sealing element 320, the first sealing element 310... The first sealing element 310 is disposed between the periphery of the supporting mesh 200 and the non-metallic polymer film 400, and the second sealing element 320 is disposed between the periphery of the annular positioning part 110 and the periphery of the non-metallic polymer film 400; the membrane window pressure plate 500 is disposed on the side of the non-metallic polymer film 400 away from the supporting mesh 200 and is fastened to the membrane window flange 100, so that the first sealing element 310 presses the supporting mesh 200 against the annular positioning part 110, and the second sealing element 320 seals the periphery of the annular positioning part 110 and the periphery of the non-metallic polymer film 400.

[0046] Understandably, the membrane window flange 100 has an annular positioning part 110 on the side that mates with the membrane window pressure plate 500, providing an installation reference for the support mesh 200 and the second sealing element 320. The support mesh 200 is disposed on the annular positioning part 110, and the periphery of the support mesh 200 is confined within the periphery of the annular positioning part 110. A non-metallic polymer film 400 with a metallized surface is disposed on the support mesh 200, and the periphery of the non-metallic polymer film 400 extends to the outside of the support mesh 200. The metallized non-metallic polymer film 400 can significantly suppress gas permeation. The support mesh 200 and the non-metallic polymer film 400 are tightly bonded together, maximizing the reinforcing effect of the support mesh 200. The thickness of the non-metallic polymer film 400 can be significantly reduced, effectively reducing energy loss, scattering, and neutron yield when the high-energy particle beam penetrates the membrane, thus ensuring beam quality. Meanwhile, the non-metallic polymer film 400 with a metal coating on its surface significantly improves the film's gas barrier properties, radiation resistance, and heat deposition resistance, thereby enhancing the vacuum performance of the membrane window and its service life under harsh working conditions.

[0047] A membrane window pressure plate 500 is disposed on the side of the non-metallic polymer film 400 away from the supporting mesh 200 and is securely connected to the membrane window flange 100. A first sealing element 310 is disposed between the periphery of the supporting mesh 200 and the non-metallic polymer film 400. When the membrane window pressure plate 500 is pressed against the membrane window flange 100, the first sealing element 310 can generate sufficient clamping force to firmly fix the supporting mesh 200 onto the annular positioning part 110, providing uniform and reliable support for the large area of ​​the non-metallic polymer film 400 in the central region, effectively reducing the film thickness so that it will not rupture under atmospheric pressure difference. At the same time, a second sealing element 320 is disposed between the periphery of the annular positioning part 110 and the periphery of the non-metallic polymer film 400, and the second sealing element 320 forms an independent and reliable outer peripheral vacuum sealing interface outside the first sealing element 310. Through the above structural design, the vacuum membrane window of this embodiment can meet the requirements of the new generation of particle therapy devices for large sizes (e.g., 270 mm × 270 mm). Technical requirements for high-reliability beam extraction windows (mm).

[0048] It should be noted that in this embodiment, by fastening the membrane window pressure plate 500 and the membrane window flange 100 together, an axial compressive force is applied to the first sealing element 310 and the second sealing element 320 disposed between them. This causes the first sealing element 310 to be compressed and deformed between the periphery of the supporting mesh 200 and the non-metallic polymer film 400, achieving reliable clamping and central support of the supporting mesh 200. At the same time, the second sealing element 320 is also compressed and tightly fitted between the periphery of the annular positioning part 110 and the periphery of the non-metallic polymer film 400, forming an independent vacuum sealing interface on the outer side. Through this sealing structure formed by the plastic deformation of soft metal, supplemented by the high gas barrier performance of the metal coating, the ultra-high vacuum performance of the membrane window area can be effectively guaranteed, allowing the membrane window area to maintain a stable 10°C for a long period of time. -9 Ultra-high vacuum in the mbar range.

[0049] It should be noted that the vacuum membrane window structure of this embodiment is suitable for particle therapy devices and can meet the requirements for beam extraction with ultra-large size, ultra-thin thickness, ultra-high vacuum, and high stability and safety.

[0050] The vacuum membrane window structure provided in this embodiment of the invention features an annular positioning part 110 on the membrane window flange 100, and a support mesh 200 and a non-metallic polymer film 400 with a metal layer on its surface arranged sequentially on the annular positioning part 110. By tightly bonding the non-metallic polymer film, the metal layer on the film, and the support mesh together, the film thickness is significantly reduced, thereby reducing energy loss, scattering, and neutron yield when high-energy particle beams penetrate the film, improving beam quality and treatment precision. Furthermore, the metal layer enhances the gas barrier performance, thermal conductivity, and radiation damage resistance of the membrane window, effectively improving the vacuum level, mitigating the thermal deposition effect, and enhancing radiation damage lifetime. Furthermore, the plated metal layer acts as a high-barrier gas barrier, effectively suppressing gas permeation from non-metallic materials, enabling a single-layer non-metallic polymer film to achieve excellent vacuum sealing performance. Additionally, the periphery of the support mesh 200 is confined within the annular positioning portion 110, while the periphery of the non-metallic polymer film 400 extends outwards and covers the support mesh 200. When the membrane window flange 100 and the membrane window pressure plate 500 are pressed together, the first sealing element 310 is clamped between the edge of the support mesh 200 and the non-metallic polymer film 400, firmly fixing the support mesh 200 to the annular positioning portion 110. This provides uniform and reliable reinforcement to the non-metallic polymer film 400, significantly reducing film thickness and minimizing the adverse effects caused by the interaction between the beam and the membrane. Simultaneously, a second sealing element 320 is provided between the outer edge of the annular positioning portion 110 and the edge of the non-metallic polymer film 400, forming a reliable peripheral vacuum sealing interface, allowing the membrane window area to maintain stable operation for a long period. -9 Ultra-high vacuum in the mbar range.

[0051] In one embodiment of the present invention, such as Figure 1 and Figure 3 As shown, the annular positioning part 110 is an annular boss that protrudes axially from the end face of the membrane flange 100, and the cross-section of the annular boss (the radial section along the membrane flange) is quadrilateral.

[0052] It is understood that the annular positioning part 110 is constructed as an annular boss protruding from the end face of the membrane window flange 100 in the axial direction. Its whole is in the shape of a closed ring, which is used to support the support mesh 200 and the non-metallic polymer film 400. The cross-section of the annular boss is quadrilateral, that is, its side wall and end face form an approximately right angle or regular rectangular geometric contour, thereby providing a clear and stable positioning reference surface and support boundary, which is conducive to assembling the support mesh 200 and cooperating with the sealing assembly 300 to achieve reliable sealing and structural fixation.

[0053] In one embodiment of the present invention, such as Figure 3As shown, the first sealing element 310 includes four first sealing wires 311, which are respectively disposed on the four straight edge areas of the annular boss. The two ends of each first sealing wire 311 extend to the outer side of the membrane window pressure plate 500 and are connected to the outer peripheral side of the annular positioning part 110 or the outer peripheral side of the membrane window pressure plate 500 through the first fastener 312. The first fastener 312 is used to apply a pre-tightening force to the first sealing wire 311. Under the pressing force applied by the membrane window pressure plate 500 to the membrane window flange 100, the force is further transmitted to the first sealing wire 311, thereby pressing the support mesh 200 against the annular positioning part 110.

[0054] Understandably, a first sealing wire 311 is arranged in each straight edge area of ​​the annular boss, so that the clamping force of each straight edge area can be applied and adjusted independently, thereby ensuring that the pressure applied to the periphery of the support mesh 200 can be precisely controlled and evenly distributed, effectively avoiding the stress concentration or pressure unevenness that may occur at the corner due to the use of a single annular sealing wire.

[0055] Both ends of each first sealing wire 311 extend to the outside of the membrane window pressure plate 500 and are connected to the first fastener 312, so that the operating end of the first fastener 312 used to tension the first sealing wire 311 is exposed to the outside, simplifying the assembly and debugging process of applying preload. Operators can easily adjust the tension or perform subsequent maintenance without disassembling the core components. The first fastener 312 applies preload to the first sealing wire 311, pressing the membrane window flange 100 and the membrane window pressure plate 500. The preload is transmitted to the lower support mesh 200 through the non-metallic polymer film 400, thereby firmly pressing and fixing the periphery of the support mesh 200 to the annular positioning part 110. This can effectively prevent the support mesh 200 from shifting, loosening or vibrating due to internal and external pressure difference in a vacuum environment or when disturbed by external forces during equipment operation, providing a stable and reliable planar support foundation for the upper fragile non-metallic polymer film 400.

[0056] For example, the four first sealing wires 311 are arranged in a "well" shape and set in the peripheral area of ​​the support mesh 200: two of the sealing wires cross the edge of the support mesh 200 in mutually perpendicular directions to form a cross structure and respectively fit into the inner side of the four straight sides of the annular positioning part 110; both ends of each first sealing wire 311 extend to the outer side of the annular positioning part 110 and are fixed to the outer periphery of the annular positioning part 110 by the first fastener 312, so as to apply a uniform clamping force to the support mesh 200 in the compressed state, and realize its reliable positioning and sealing on the annular positioning part 110.

[0057] In one embodiment of the present invention, such as Figure 3 and Figure 4As shown, the second seal 320 can have the same structure as the first seal 310. For example, the second seal 320 includes four second sealing wires 321, which are respectively disposed on the four straight-edge regions of the annular boss and located outside the first sealing wires 311. Both ends of each second sealing wire 321 extend to the outer side of the membrane window pressure plate 500 and are connected to the outer periphery of the annular positioning portion 110 or the outer periphery of the membrane window pressure plate 500 via second fasteners 322. The second fasteners 322 are used to apply a pre-tightening force to the second sealing wires 321. Under the pressing force applied by the membrane window pressure plate 500 to the membrane window flange 100, this force is further transmitted to the second sealing wires 321 to seal the periphery of the annular positioning portion 110 and the periphery of the non-metallic polymer film 400.

[0058] Understandably, the four second sealing wires 321 can also be arranged in a "well" shape, located outside the first sealing wire 311, corresponding to the periphery of the annular positioning part 110, and in contact with the outwardly extending edge of the non-metallic polymer film 400; both ends of each second sealing wire 321 extend to the outside of the annular positioning part 110 and are fixed to the outer periphery of the annular positioning part 110 by the second fastener 322; when the membrane window pressure plate 500 and the membrane window flange 100 are pressed together, the second sealing wires 321 are compressed and deformed, thereby forming a tight fit between the periphery of the annular positioning part 110 and the periphery of the non-metallic polymer film 400, forming an independent vacuum sealing interface on the outside.

[0059] It should be noted that the second fastener 322 applies a controllable preload to the flexible second sealing wire 321. During the pressing process between the membrane window pressure plate 500 and the membrane window flange 100, the second sealing wire 321 can undergo slight plastic deformation, thereby completely filling the space between the annular positioning part 110 and the non-metallic polymer film 400, achieving metal-level airtightness. Combined with the metal coating, this ultimately ensures the vacuum performance and long-term stability of the entire vacuum membrane window structure.

[0060] In one embodiment of the present invention, the first fastener 312 is a connecting bolt connected to the outer periphery of the annular positioning part 110. By rotating the connecting bolt, it is convenient to apply and adjust the tension to the end of the first sealing wire 311 extending to the outside of the membrane window pressure plate 500, thereby achieving precise control of the pre-tightening force.

[0061] It should be noted that the second fastener 322 can also be a connecting bolt. The connecting bolt is installed on the outer periphery of the annular positioning part 110 and is used to apply a pre-tightening force to the second sealing thread 321, thereby achieving reliable fixation and sealing of the outer periphery sealing structure.

[0062] It should be noted that the first fastener 312 and the second fastener 322 can also be connecting bolts connected to the outer periphery of the membrane window pressure plate 500.

[0063] In one embodiment of the present invention, the first sealing wire 311 is a metal sealing wire, which may optionally be a sealing aluminum wire or a sealing silver wire, in order to balance good sealing performance with appropriate plastic deformation capacity.

[0064] Similarly, the second sealing wire 321 is also a metal sealing wire, and sealing aluminum wire or sealing silver wire can also be selected, so as to achieve a highly reliable vacuum sealing effect in the outer peripheral sealing area.

[0065] It should be noted that the first sealing wire 311 and the second sealing wire 321 are made of aluminum wire. Utilizing the softness and good ductility of aluminum, under the pressure applied by the membrane window pressure plate 500, the aluminum wire can undergo plastic deformation, effectively filling and pressing into the area between the membrane window flange 100 and the non-metallic polymer film 400, forming a continuous and dense metal sealing ring, achieving excellent compression and sealing effects. Furthermore, aluminum has a low outgassing rate in ultra-high vacuum environments, and as a sealing material, it will not continuously pollute the vacuum environment, helping to quickly obtain and maintain the vacuum level required for the membrane window structure over a long period.

[0066] In one embodiment of the present invention, the non-metallic polymer film 400 is a Hostaphan Polyester Film (Hostaphan film). As a high-quality biaxially oriented polyethylene terephthalate (BoPET) film, it possesses excellent mechanical strength and superior dimensional stability. This allows the film to effectively resist deformation and stretching when subjected to pressure differences between the inside and outside of a vacuum chamber, thereby ensuring the overall integrity of the membrane window structure and its long-term reliability. Simultaneously, the smooth and flat surface of the Hostaphan film greatly facilitates the uniform deposition and firm adhesion of the subsequent metal layer, avoiding uneven coating or pinhole problems caused by surface defects, thus ensuring the stable realization of the metal layer's function.

[0067] Optionally, the thickness of the Hostaphan membrane ranges from 10 μm to 75 μm. A thickness of at least 10 μm ensures sufficient structural strength and puncture resistance to withstand mechanical stresses during assembly and long-term pressure differential between the atmosphere and vacuum during operation, effectively preventing the risk of rupture or failure due to excessive membrane thickness. The upper limit of 75 μm is primarily for engineering redundancy to account for potential reverse impact loads in the event of an unexpected vacuum breach, thereby enhancing overall safety margin.

[0068] It should be noted that, based solely on theoretical calculations or ideal operating conditions, the thickness of the Hostaphan membrane can typically be controlled within the range of 10μm to 20μm to meet the requirements for core performance such as membrane window strength and vacuum sealing.

[0069] Optionally, the metal layer on the surface of the Hostaphan membrane is a low-density metal layer to reduce beam energy loss, scattering, and neutron yield.

[0070] In this embodiment, the surface of the Hostaphan membrane can be coated with an aluminum layer to form a continuous and dense aluminum layer thereon. The thickness of the aluminum layer is controlled within the range of 1 μm to 5 μm. The metallization treatment of the Hostaphan membrane not only significantly enhances its barrier properties against gas permeation, but also improves the membrane's resistance to radiation and thermal deposition, further ensuring the long-term stability and reliability of the vacuum window in an ultra-high vacuum environment.

[0071] It should be noted that in existing particle therapy devices, as the beam extraction window size increases to 270 mm × 270 mm, traditional solutions require two independent membrane-membrane systems forming a sandwich structure, with an additional secondary vacuum (maintained at approximately 1 Pa) between the two systems to address the high gas permeability problem inherent in the membrane itself. This approach results in a total membrane window thickness of at least 300 μm and necessitates a complex vacuum extraction system, significantly increasing construction and operating costs. In contrast, this embodiment utilizes a single-layer 10 μm to 75 μm thick Hostaphan membrane reinforced with a high-tensile-strength mesh and coated with a 1 μm to 5 μm aluminum layer, effectively suppressing gas permeation. A single membrane-membrane system is sufficient to meet the mechanical strength and vacuum performance requirements. Simultaneously, the aluminum coating significantly enhances the membrane's heat dissipation capacity and radiation damage resistance. Combined with a simple and easily replaceable metal sealing structure, this greatly simplifies the system structure and reduces costs.

[0072] Optionally, the non-metallic polymer film 400 may have a metal layer deposited on one side or on both sides. Preferably, when a metal layer is deposited on one side, the metal layer is deposited on the side of the non-metallic polymer film 400 closest to the support mesh 200.

[0073] In one embodiment of the present invention, the corners of the annular positioning part 110 that contact the Hostaphan membrane are rounded and finely deburred. The rounded corner design effectively avoids sharp edges or micro-burrs from causing scratches, perforations, or stress concentrations to the non-metallic polymer film 400 during assembly or operation, thereby significantly improving the reliability and service life of the membrane window structure and ensuring the safety and integrity of the Hostaphan membrane when subjected to clamping force and vacuum differential pressure.

[0074] In one embodiment of the present invention, the support mesh 200 is a high tensile strength support mesh, which is five times stronger than steel and has extremely strong thermal stability and impact resistance.

[0075] Optionally, the support mesh 200 is made of KAPTON KEVLAR 49 composite material. KAPTON is a registered high-performance polyimide brand of DuPont, known for its excellent high-temperature resistance, mechanical strength, and vacuum compatibility. KEVLAR 49 is a high-modulus aramid fiber (i.e., poly(p-phenylene terephthalamide), PPTA) developed by DuPont, renowned for its extremely high tensile strength, low density, and excellent impact resistance. KAPTON KEVLAR 49 mesh refers to a composite mesh material with KEVLAR 49 fiber as the reinforcing skeleton and a surface coated or composited with KAPTON polyimide. It combines lightweight, high strength, radiation resistance, and good dimensional stability, making it particularly suitable for support applications in high-vacuum, high-energy particle beam environments. It can provide uniform and reliable central support for non-metallic polymer films 400 while reducing interference with particle beams.

[0076] In one embodiment of the present invention, the membrane window flange 100 and the membrane window pressure plate 500 are made of 304 stainless steel, which has good mechanical strength, corrosion resistance and excellent vacuum compatibility, and can work stably for a long time in a high vacuum environment. At the same time, it is easy to process and form and surface treat, ensuring that a reliable and durable sealing interface is formed when it is used with the sealing element.

[0077] Based on the vacuum membrane window structure provided in any of the above embodiments, a second aspect of the present invention proposes a method for processing a vacuum membrane window structure, the method comprising the following steps:

[0078] Step 10: Prepare membrane window flange 100, membrane window pressure plate 500, first sealing element 310 and second sealing element 320, and machine an annular positioning part 110 on membrane window flange 100.

[0079] Step 20: Clean the non-metallic polymer film 400, the membrane window flange 100, the membrane window pressure plate 500, the first seal 310, and the second seal 320.

[0080] Step 30: Vacuum degassing is performed on the cleaned membrane window flange 100, membrane window pressure plate 500, first seal 310 and second seal 320.

[0081] Step 40: Metal is deposited on the cleaned non-metallic polymer film 400 to form a metal layer on the surface of the non-metallic polymer film 400.

[0082] Step 50: Assemble the membrane window flange 100, support mesh 200, non-metallic polymer film 400 and membrane window pressure plate 500 in sequence, and place the first sealing member 310 between the periphery of the support mesh 200 and the non-metallic polymer film 400, and seal the second sealing member 320 between the periphery of the annular positioning part 110 and the periphery of the non-metallic polymer film 400.

[0083] Step 60: Tighten the membrane window flange 100 and the membrane window pressure plate 500 so that the first sealing member 310 presses the support liner 200 against the annular positioning part 110, and the second sealing member 320 seals the periphery of the annular positioning part 110 and the periphery of the non-metallic polymer film 400.

[0084] Understandably, the process involves several steps: First, a membrane window flange 100, a membrane window pressure plate 500, a first seal 310, and a second seal 320 are prepared, with an annular positioning portion 110 machined on one side of the membrane window flange 100. Then, the non-metallic polymer film 400, membrane window flange 100, membrane window pressure plate 500, first seal 310, and second seal 320 are thoroughly cleaned to remove surface contaminants. Next, the cleaned metal components (including the membrane window flange 100, membrane window pressure plate 500, first seal 310, and second seal 320) undergo vacuum degassing to remove internal gases and ensure high vacuum compatibility. Finally, a coating process is applied to the cleaned non-metallic polymer film 400 to form a metal layer (such as an aluminum layer) of controllable thickness, thereby significantly enhancing the gas permeation barrier properties of the non-metallic film and obtaining a composite non-metallic membrane with ultra-high vacuum performance. It is a polymer film; then, the membrane window flange 100, the support mesh 200, the coated non-metallic polymer film 400, and the membrane window pressure plate 500 are assembled in sequence, wherein the first sealing element 310 is placed between the periphery of the support mesh 200 and the non-metallic polymer film 400, and the second sealing element 320 is arranged between the periphery of the annular positioning part 110 and the periphery of the non-metallic polymer film 400; finally, by fastening the membrane window pressure plate 500 and the membrane window flange 100, an axial clamping force is applied, so that the first sealing element 310 firmly presses the support mesh 200 onto the annular positioning part 110, providing uniform and reliable central support for the non-metallic polymer film 400, while the second sealing element 320 forms a dense and independent outer peripheral vacuum sealing interface between the annular positioning part 110 and the edge of the non-metallic polymer film 400, ultimately achieving high reliability and ultra-high vacuum (up to 10). -9 A membrane window structure (on the order of mbar).

[0085] In this embodiment, the vacuum membrane window structure processing method includes the following steps:

[0086] S1. According to the designed dimensions, the membrane window flange 100 and the membrane window pressure plate 500 are machined by CNC machine tools; wherein, the annular positioning part 110 is machined on the membrane window flange 100.

[0087] S2. The roughness of the sealing surface of the annular positioning part 110 (the surface that mates with the non-metallic polymer film 400 and the second sealing element 320) is processed by a CNC machine tool so that the roughness of the sealing surface is better than 0.8 μm.

[0088] S3. The edges of the ring positioning part 110 that are in contact with the Hostaphan film are rounded by a CNC machine tool and then finely deburred to prevent the non-metallic polymer film 400 from being scratched or damaged when it deforms.

[0089] It should be noted that, in order to ensure assembly accuracy and overall performance, the dimensions and geometric tolerances of the membrane window flange 100 and the membrane window pressure plate 500 need to be inspected. This measurement work is completed by a high-precision coordinate measuring machine to verify whether its key dimensions, positioning surfaces and installation datums meet the design requirements, thereby ensuring that each component can be accurately positioned during the assembly process, achieving reliable sealing, uniform clamping force distribution and stable vacuum and mechanical properties.

[0090] S4. Process the first seal 310 and the second seal 320.

[0091] Specifically, eight sealing aluminum wires made of high-quality pure aluminum are cut, of which four sealing aluminum wires (first sealing wire 311) are used as the first sealing element 310, and the remaining four sealing aluminum wires (second sealing wire 321) are used as the second sealing element 320.

[0092] S5. Perform ultrasonic cleaning on the processed non-metallic polymer film 400, membrane window flange 100, membrane window pressure plate 500, first seal 310 and second seal 320 to remove the oil stains adsorbed on the surface.

[0093] S6. Vacuum degassing is performed on the cleaned membrane window flange 100, membrane window pressure plate 500, first seal 310 and second seal 320.

[0094] Specifically, the cleaned membrane window flange 100 and membrane window pressure plate 500 need to be subjected to a vacuum degree better than 1×10 -3 Vacuum degassing is performed in a high-temperature furnace with a temperature of up to 1000℃. The holding time is calculated based on the wall thickness of the workpiece, usually 1 hour per millimeter of wall thickness, in order to effectively remove the gas (especially hydrogen) adsorbed inside the material and the residual impurities on the surface, thereby improving its ultra-high vacuum compatibility.

[0095] For the first seal 310 and the second seal 320 (i.e., the sealing aluminum wire) after cleaning, the vacuum degree is better than 1×10-3 The aluminum is kept at 400℃ for 1 hour under the condition of Pa. This heat treatment process eliminates the internal residual stress and improves the plasticity and ductility of the pure aluminum material. This ensures that the sealing aluminum wire is not easy to break during the pre-assembly process and can fully fit the sealing surface of the membrane window flange 100 and the surface of the non-metallic polymer film 400 during subsequent compression sealing, forming a reliable and dense vacuum sealing interface.

[0096] S7. A multi-target DC magnetron sputtering coating machine is used to coat the cleaned non-metallic polymer film 400 with aluminum to form a metal layer on the surface of the non-metallic polymer film 400.

[0097] S8. Cut the KEVLAR 49 fiber lining according to the assembly dimensions required by the design to obtain a support lining 200 that fits the annular positioning part 110.

[0098] S9. Assemble the membrane window flange 100, the support mesh 200, the non-metallic polymer film 400, and the membrane window pressure plate 500 in sequence from vacuum to atmosphere.

[0099] Meanwhile, four first sealing wires 311 are disposed around the periphery of the support mesh 200 and between the non-metallic polymer film 400. Each first sealing wire 311 extends an annular positioning portion 110 at both ends and is wound around a first fastener 312 connected to the outer periphery of the annular positioning portion 110, so that the support mesh 200 is fixed to the sealing surface of the annular positioning portion 110 by the four first sealing wires 311; and the first sealing wires 311 are pre-tightened by rotating the first fastener 312 to strengthen the positioning of the support mesh 200.

[0100] Four second sealing wires 321 are disposed between the periphery of the annular positioning part 110 and the periphery of the non-metallic polymer film 400. The two ends of each second sealing wire 321 are connected to the outer periphery of the annular positioning part 110 by a second fastener 322. The second sealing wires 321 can also be pre-tightened by rotating the second fastener 322 to enhance the seal between the periphery of the annular positioning part 110 and the periphery of the non-metallic polymer film 400.

[0101] It should be noted that the first sealing wire 311 is located between the support liner 200 and the non-metallic polymer film 400, which can buffer the adverse effects of the support liner 200 on the non-metallic polymer film 400 during the pressing process.

[0102] S10 connects the membrane window flange 100 and the membrane window pressure plate 500, continuously pressing them together. During this pressing process, the annular positioning part 110 of the membrane window flange 100, the second sealing wire 321, and the non-metallic polymer film 400 together form the sealing surface of the entire membrane window. Simultaneously, the first sealing wire 311 continuously positions the support mesh 200 to ensure it can withstand the atmospheric pressure transmitted from the non-metallic polymer film 400. After assembly, helium mass spectrometry leak detection is performed, and the overall leakage rate of the membrane window is found to be better than 5 × 10⁻⁶. -10 mbar·L / s (mbar·liter per second) meets the stringent sealing requirements of ultra-high vacuum applications.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A vacuum membrane window structure, characterized in that, include: A membrane window flange, wherein an annular positioning part is provided on one side of the membrane window flange; A supporting mesh is disposed in the annular positioning part, and the periphery of the supporting mesh is located inside the periphery of the annular positioning part; A non-metallic polymer film is disposed on the side of the support mesh opposite to the annular positioning part, the periphery of the non-metallic polymer film extends to the outside of the support mesh, and the surface of the non-metallic polymer film is coated with a metal layer. A sealing assembly includes a first sealing element and a second sealing element, wherein the first sealing element is disposed between the periphery of the supporting mesh and the non-metallic polymer film, and the second sealing element is disposed between the periphery of the annular positioning portion and the periphery of the non-metallic polymer film. A membrane window pressure plate is disposed on the side of the non-metallic polymer film away from the supporting mesh and is fastened to the membrane window flange, so that the first sealing member presses the supporting mesh against the annular positioning part, and the second sealing member seals the area between the periphery of the annular positioning part and the periphery of the non-metallic polymer film. The first sealing element includes four first sealing wires, which are respectively disposed in the four straight-edge areas of the annular positioning part. Both ends of each first sealing wire extend to the outer side of the membrane window pressure plate and are connected to the outer periphery of the annular positioning part or the outer periphery of the membrane window pressure plate via first fasteners. The first fasteners are used to apply a pre-tightening force to the first sealing wires. The second sealing element includes four second sealing wires, which are respectively disposed in the four straight-edge areas of the annular positioning part and located outside the first sealing wires. Both ends of each second sealing wire extend to the outer side of the membrane window pressure plate and are connected to the outer periphery of the annular positioning part or the outer periphery of the membrane window pressure plate via second fasteners. The second fasteners are used to apply a pre-tightening force to the second sealing wires.

2. The vacuum membrane window structure according to claim 1, characterized in that, The annular positioning part is an annular boss that protrudes axially from the end face of the membrane window flange, and the cross-section of the annular boss is quadrilateral.

3. The vacuum membrane window structure according to claim 1, characterized in that, The first fastener is a connecting bolt connected to the outer periphery of the annular positioning part.

4. The vacuum membrane window structure according to claim 1, characterized in that, The second fastener is a connecting bolt connected to the outer periphery of the annular positioning part.

5. The vacuum membrane window structure according to claim 1, characterized in that, The first sealing wire is a sealing aluminum wire or a sealing silver wire, and / or, The second sealing wire is a sealing aluminum wire or a sealing silver wire.

6. The vacuum membrane window structure according to any one of claims 1 to 5, characterized in that, The non-metallic polymer film is a Hostaphan film.

7. The vacuum membrane window structure according to claim 6, characterized in that, The thickness of the non-metallic polymer film is 10 μm to 75 μm.

8. The vacuum membrane window structure according to claim 6, characterized in that, The metal layer is an aluminum layer with a thickness of 1μm to 5μm.

9. The vacuum membrane window structure according to any one of claims 1 to 5, characterized in that, The annular positioning part is provided with rounded corners.

10. A method for processing a vacuum membrane window structure, characterized in that, include: Prepare a membrane window flange, a membrane window pressure plate, a first sealing element, and a second sealing element, and machine an annular positioning part on the membrane window flange; The non-metallic polymer film, the membrane window flange, the membrane window pressure plate, the first seal and the second seal are cleaned. Vacuum degassing is performed on the cleaned membrane window flange, the membrane window pressure plate, the first seal, and the second seal. Metal is plated onto the surface of the cleaned non-metallic polymer film to form a metal layer on the surface of the non-metallic polymer film. The membrane window flange, supporting mesh, non-metallic polymer film, and membrane window pressure plate are assembled sequentially. The first sealing element is positioned between the periphery of the supporting mesh and the non-metallic polymer film, and the second sealing element is positioned between the periphery of the annular positioning portion and the periphery of the non-metallic polymer film. The first sealing element comprises four first sealing wires, each corresponding to one of the four straight-edge regions of the annular positioning portion. Both ends of each first sealing wire extend to the outer side of the membrane window pressure plate and are connected to the outer periphery of the annular positioning portion or the membrane window pressure plate via a first fastener. The first fastener applies a pre-tightening force to the first sealing wire. The second sealing element comprises four second sealing wires, each corresponding to one of the four straight-edge regions of the annular positioning portion and located outside the first sealing wires. Both ends of each second sealing wire extend to the outer side of the membrane window pressure plate and are connected to the outer periphery of the annular positioning portion or the membrane window pressure plate via a second fastener. The second fastener applies a pre-tightening force to the second sealing wire. The membrane window flange and the membrane window pressure plate are pressed together so that the first sealing member presses the support mesh against the annular positioning part, and the second sealing member seals the area between the periphery of the annular positioning part and the periphery of the non-metallic polymer film.

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