Accelerating tube and linear accelerator comprising same

Abstract

The utility model relates to the technical field of linear accelerators, in particular to an accelerating tube and a linear accelerator comprising the same. The accelerating tube is composed of a plurality of accelerating cavities and fence pieces. Each acceleration cavity is welded with one column piece to form a complete acceleration structure, all the acceleration structures are welded to form an acceleration tube body, and each column piece is provided with a beam hole, so that all the acceleration cavities are communicated with one another to form a complete beam transmission channel; the accelerating cavity comprises a phase velocity changing section and a light velocity section; the input coupling cavity and the output coupling cavity are both of a cylindrical inner cavity structure, and cavity bodies of the other accelerating cavities are each composed of two symmetrical bowl-shaped inner cavity structures. According to the utility model, the main body part of the accelerating tube body adopts the bowl-shaped inner cavity structure, and the phase velocity change of each accelerating structure is reasonably set, so that the passing efficiency of beam current and the utilization efficiency of radio frequency power are improved while the electron beam is ensured to have good stability and better energy dispersion.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of linear accelerator, concretely relates to an accelerating tube and linear accelerator including it. BACKGROUND

[0002] With the continuous popularization of nuclear technology, irradiation technology has become an important processing method due to its unique advantages. Compared with traditional chemical treatment and heat treatment methods, irradiation technology has the characteristics of high efficiency, environmental protection, strong controllability, etc. Especially in the modification of materials, sterilization and disinfection, and food preservation, irradiation technology can significantly improve the processing effect, prolong the service life of the product, and reduce the pollution to the environment. Electron accelerators are widely used as one of the stable and reliable irradiation sources.

[0003] An electron accelerator is a device that accelerates and utilizes electrons using an electric field. It is widely used in various fields, including material modification, sterilization and disinfection, food preservation, semiconductor manufacturing, and waste treatment. By accelerating electrons and directing them to the material to be processed, the electron accelerator can achieve efficient and pollution-free irradiation processing. The existing commonly used electron accelerators can be divided into three categories according to the energy range: (1) low-energy accelerator (80keV-300keV), the main representative is the electron curtain accelerator. It is a high-voltage accelerator but does not have an accelerating tube and a scanning device, with the characteristics of simple structure, small size, and self-shielding. The beam power is generally 150kW to 200kW. This type of accelerator is mainly used for radiation processing of thin layer materials or surface coatings; (2) medium-energy accelerator (0.3MeV-5MeV), the main representative is the Denatron accelerator, with a power of several tens or even hundreds of kilowatts, mainly used in the fields of radiation crosslinking of polyethylene insulation materials of electric wires and cables and polyethylene foamed plastic materials; (3) high-energy accelerator (5MeV-10MeV), this type of accelerator is mainly an electron linear accelerator, which uses microwave acceleration particles and can be divided into traveling wave accelerators and standing wave accelerators according to the type of microwave used. This type of accelerator has high output energy and output power of several kilowatts or even tens of kilowatts, but due to the limitation of industrial radiation safety, the maximum energy is generally 10MeV. This type of accelerator is mainly used for irradiation sterilization of medical drugs and food, modification of electronic components, and tire vulcanization. Compared with the other two types of accelerators, the electron linear accelerator has the characteristics of high energy, precise control, and functional diversity, and is more widely used.

[0004] In the related art, a low-energy large-flow forced wave accelerating tube with application number 201920891271.9 includes an accelerating tube body, input and output couplers connected to the two ends of the side of the accelerating tube body; the accelerating tube body is a disc-loaded waveguide, and seven accelerating chambers are arranged inside, adjacent accelerating chambers are separated by discs, and the length of the segmented accelerating chambers is increased by 1.2 times; the first to sixth accelerating chambers are bunching chambers, and the seventh accelerating chamber is a light speed chamber. By arranging a plurality of uniformly changing accelerating chambers in the accelerating tube, and input and output couplers at the two ends of the accelerating tube, the energy of the output electron beam can reach the megavolt level, the power is greater than 1kW, and the accelerating tube has the advantages of small size, compact structure and easy protection. However, the above structure still has the following problems: the accelerating tube body adopts a cylindrical inner cavity structure, and the stability and energy dispersion performance of the electron beam are poor. Utility model content

[0005] The utility model aims at solving one of the technical problems in the prior art. To this end, the utility model aims at providing an accelerating tube and a linear accelerator comprising the same, which combines the advantages of a bowl-shaped inner cavity structure and a cylindrical inner cavity structure, adopts a bowl-shaped inner cavity structure in the main body part of the accelerating tube body, and improves the through efficiency of the beam and the utilization efficiency of the radio frequency power by reasonably setting the phase velocity change of each accelerating structure while ensuring that the electron beam has good stability and good energy dispersion. The cylindrical inner cavity structure is retained in the input coupling cavity and the output coupling cavity to facilitate power coupling.

[0006] The utility model provides an accelerating tube in a first aspect;

[0007] The accelerating tube is composed of a plurality of accelerating chambers and a plurality of bars; each accelerating chamber is welded with a bar to form a complete accelerating structure, and all the accelerating structures are welded to form an accelerating tube body, wherein a beam hole is arranged on each bar to enable all the accelerating chambers to communicate with each other to form a complete beam transmission path; the cavity of the first accelerating chamber in the direction of electron beam movement is an input coupling cavity, and the cavity of the last accelerating chamber in the direction of electron beam movement is an output coupling cavity;

[0008] The accelerating chamber includes a variable velocity segment and a light speed segment which are sequentially communicated in the direction of electron beam movement; the variable velocity segment is used for bunching and phase slipping of the electron beam, and the light speed segment is used for improving the energy of the electron beam;

[0009] The input coupling cavity is a cylindrical inner cavity structure, the output coupling cavity is a cylindrical inner cavity structure, and the cavities of the remaining accelerating chambers are composed of two symmetrical bowl-shaped inner cavity structures.

[0010] In the first aspect of the utility model, as a kind of preferred embodiment, the number of acceleration cavity is sixty, wherein, the cavity of the first acceleration cavity to the cavity of the third acceleration cavity along the direction of electron beam motion is mainly used for bunching, the cavity of the fourth to the seventh acceleration cavity is mainly used for slip phase, the cavity of the eighth to the sixtieth acceleration cavity constitutes light speed section;The cavity of the first acceleration cavity is input coupling cavity, and the cavity of the sixtieth acceleration cavity is output coupling cavity.

[0011] In the first aspect of the utility model, as a kind of preferred embodiment, the total length of the acceleration tube body is 2043.054mm, and the thickness of the sheet is 5.5mm.

[0012] In the first aspect of the utility model, as a kind of preferred embodiment, the edge of the beam hole forms oval structure.

[0013] In the first aspect of the utility model, as a kind of preferred embodiment, the ratio of major axis and minor axis of the oval structure of the beam hole edge is 1.8:1.

[0014] In the first aspect of the utility model, as a kind of preferred embodiment, the major axis of the oval structure of the beam hole edge is 4.95mm, and the minor axis is 2.75mm.

[0015] In the first aspect of the utility model, as a kind of preferred embodiment, the aperture of the beam hole of all sheets decreases in turn.

[0016] In the first aspect of the utility model, as a kind of preferred embodiment, the cavity radius of the acceleration cavity of the phase velocity variation section gradually increases along the direction of electron beam motion, and the cavity radius of the first acceleration cavity of light speed section reaches maximum value, and the cavity radius of the acceleration cavity of light speed section gradually decreases along the direction of electron beam motion;The cavity length of the acceleration cavity of the phase velocity variation section gradually increases along the direction of electron beam motion, and the cavity length of the acceleration cavity of light speed section remains unchanged.

[0017] In the first aspect of the utility model, as a kind of preferred embodiment, the phase velocity β p of the RF field of the phase velocity variation section gradually transitions from 0.54 to 1, and the phase velocity β p of the RF field of the light speed section is 1.

[0018] The utility model discloses a second aspect provides at a kind of linear accelerator, including the accelerating tube of the utility model first aspect, input coupler skew waveguide, output coupler skew waveguide, first drift tube and second drift tube;Input coupler skew waveguide is communicated with input coupling cavity, for introducing external radio frequency power into accelerator;Output coupler skew waveguide is communicated with output coupling cavity, for guiding remaining microwave power export;First drift tube is communicated with input coupling cavity, for providing the passageway of electron beam into accelerating cavity;Second drift tube is communicated with output coupling cavity, for providing the passageway of electron beam after acceleration to leave accelerating cavity.

[0019] Compared with the prior art, the utility model has the beneficial effects that:

[0020] The embodiment adopts cylindrical inner cavity structure in input coupling cavity and output coupling cavity part, to facilitate power coupling.Bowl-shaped inner cavity structure is adopted in the main part of accelerating tube body, and the design of bowl-shaped inner cavity structure optimizes the distribution of electromagnetic field by changing the shape and size of the cavity of accelerating cavity, so as to improve shunt impedance R and quality factor Q value.Under the action of optimized electromagnetic field, microwave power can be more efficiently converted to electron beam, realizing the acceleration of electron beam.In the case of obtaining equal energy gain, since power consumption loss is reduced, the heat generated on the wall of accelerating tube body is less, so that the cooling pressure of water cooling system is reduced.Above all, the embodiment combines the advantages of bowl-shaped inner cavity structure and cylindrical inner cavity structure, adopts bowl-shaped inner cavity structure in the main part of accelerating tube body, and improves the through efficiency of beam and the utilization efficiency of radio frequency power by reasonably setting the phase velocity variation of each accelerating structure, while ensuring that electron beam has good stability and better energy dispersion;Cylindrical inner cavity structure is retained in input coupling cavity and output coupling cavity part to facilitate power coupling. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is the partial structure sectional view of the accelerating tube of the utility model;

[0022] Figure 2 It is the accelerating tube structure schematic view of the utility model;

[0023] Figure 3 It is the structure schematic view of another angle of the accelerating tube of the utility model;

[0024] Figure 4 It is the sectional view of the linear accelerator of the utility model.

[0025] In the figure: 100, accelerating tube; 10, accelerating tube body; 11, accelerating cavity; 110, cavity of accelerating cavity; 111, variable phase velocity section; 112, light velocity section; 113, input coupling cavity; 114, output coupling cavity; 20, barrier piece; 21, beam hole; 200, input coupling inclined waveguide; 300, output coupling inclined waveguide; 400, first drift tube; 500, second drift tube. DETAILED DESCRIPTION

[0026] Hereinafter, the utility model will be further described in conjunction with the drawings and specific embodiments, it should be noted that, without conflict, the following described embodiments or between the technical features can be arbitrarily combined to form a new embodiment. Except for the special description, the materials and equipment used in the embodiments can be purchased from the market. Examples of embodiments are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the drawings are exemplary and are only used to explain the present application and cannot be understood as limiting the present application.

[0027] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore cannot be understood as limiting the present application. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically specified and limited.

[0028] In the description of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected", "communicated", "connected" should be understood in a broad sense, for example, it can be fixedly connected, it can be connected through an intermediate medium, it can be internal communication of two elements or interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0029] The terms "first", "second", and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily describe a particular order or sequence. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not necessarily limit to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0030] Embodiment One

[0031] Please refer to Figures 1-4 The embodiment provides an acceleration tube 100.

[0032] The acceleration tube 100 is composed of a plurality of acceleration cavities 11 and a plurality of plates 20; each of the acceleration cavities 11 and one of the plates 20 are welded to form a complete acceleration structure, and all the acceleration structures are welded to form an acceleration tube body 10, wherein a beam hole 21 is arranged on each of the plates 20, so that all the acceleration cavities 11 are communicated with each other to form a complete beam transmission path; wherein the cavity 110 of the first acceleration cavity in the direction of the electron beam is an input coupling cavity 113, and the cavity 110 of the last acceleration cavity in the direction of the electron beam is an output coupling cavity 114.

[0033] The acceleration tube body 10 includes a variable phase velocity section 111 and a light velocity section 112 which are communicated in sequence in the direction of the electron beam; the variable phase velocity section 111 is used for beam focusing and phase slip, and the light velocity section 112 is used for improving the energy of the electron beam.

[0034] The input coupling cavity 113 is a cylindrical inner cavity structure, the output coupling cavity 114 is a cylindrical inner cavity structure, and the cavities 110 of the remaining acceleration cavities are composed of two symmetrical bowl-shaped inner cavity structures.

[0035] On the basis of the above structure, the cylindrical inner cavity structure is adopted in the input coupling cavity 113 and the output coupling cavity 114, so as to facilitate power coupling. The bowl-shaped inner cavity structure is adopted in the main part of the acceleration tube body 10. The design of the bowl-shaped inner cavity structure optimizes the distribution of the electromagnetic field by changing the shape and size of the cavity 110 of the acceleration cavity, thereby improving the shunt impedance R and the quality factor Q value. Under the action of the optimized electromagnetic field, the microwave power can be more efficiently converted to the electron beam to realize the acceleration of the electron beam. In the case of obtaining the same energy gain, the power loss is reduced, so that the heat generated on the wall of the acceleration tube body 10 is less, thereby reducing the cooling pressure of the water cooling system. In summary, the embodiment combines the advantages of the bowl-shaped inner cavity structure and the cylindrical inner cavity structure, adopts the bowl-shaped inner cavity structure in the main part of the acceleration tube body 10, and improves the passing efficiency of the beam and the utilization efficiency of the radio frequency power by reasonably setting the phase velocity change of each acceleration structure while ensuring that the electron beam has good stability and good energy dispersion; and the cylindrical inner cavity structure is retained to facilitate power coupling.

[0036] As a preferred embodiment, the acceleration tube body 10 is welded together by a plurality of acceleration structures.

[0037] As a preferred embodiment, the number of acceleration cavities 11 is sixty, wherein the cavities 110 of the first to third acceleration cavities are mainly used for bunching along the direction of motion of the electron beam, the cavities 110 of the fourth to seventh acceleration cavities are mainly used for phase slipping, and the cavities 110 of the eighth to sixtieth acceleration cavities constitute the light speed section 112; the cavity 110 of the first acceleration cavity is the input coupling cavity 113, and the cavity 110 of the sixtieth acceleration cavity is the output coupling cavity 114.

[0038] On the basis of the above structure, the electron beam enters the input coupling cavity 113 from one end of the acceleration tube body 10, passes through the cavities 110 of the first to third acceleration cavities to form a beamlet, and the beamlet from the electron gun is formed into a plurality of beamlets with a relatively short phase length. Then, the electron beam enters the cavities 110 of the fourth to seventh acceleration cavities for phase adjustment, so that the beamlet can be located exactly at the peak phase -90° of the sinusoidal wave acceleration electric field when entering the light speed section 112. Finally, the electron beam continues to increase the energy in the light speed section 112, and the finally accelerated electron beam smoothly exits the acceleration tube body 10 through the output coupling cavity 114, providing a high-quality electron beam source for subsequent experiments or applications. In this way, the present application realizes efficient beamlet formation of the electron beam by designing the phase velocity section 111, reduces the energy dispersion of the beam at the outlet of the acceleration tube body 10, ensures that the beamlet can be located exactly at the peak phase -90° of the sinusoidal wave acceleration electric field when entering the light speed section 112, and improves the acceleration efficiency.

[0039] As a preferred embodiment, the total length of the acceleration tube body 10 is 2043.054mm, and the thickness of the barrier sheet 20 is 5.5mm.

[0040] On the basis of the above structure, the reasonable total length of the acceleration tube body 10 can ensure that the electron beam obtains sufficient energy during the acceleration process, while maintaining the compactness and cost-effectiveness of the accelerator. The appropriate thickness of the barrier sheet 20 can reduce the phase velocity of the electromagnetic field, improve the mechanical strength, facilitate the chamfering of the beam hole 21, and be conducive to reducing the breakdown voltage.

[0041] As a preferred embodiment, the edge of the beam hole 21 forms an elliptical structure.

[0042] On the basis of the above structure, the elliptical structure can effectively reduce the ratio of the surface electric field to the acceleration gradient. At the same time, the design of the elliptical structure also helps to reduce the surface electric field strength, reduce the discharge or breakdown phenomenon that may be caused by high surface electric field, and further improve the stability and reliability of the acceleration tube 100.

[0043] As a preferred embodiment, the ratio of the major axis to the minor axis of the elliptical structure of the beam hole edge is 1.8:1. The major axis of the elliptical structure of the beam hole edge is 4.95 mm, and the minor axis is 2.75 mm.

[0044] On the basis of the above structure, by accurately designing the major axis, the minor axis and the ratio of the major axis to the minor axis of the elliptical structure of the beam hole edge, the distribution and intensity of the electromagnetic field can be optimized, so that the electron beam receives more uniform and stable acceleration force during the acceleration process.

[0045] As a preferred embodiment, the aperture of the beam hole 21 of all the segments 20 decreases in turn. As a preferred embodiment, the radius of the cavity 110 of the acceleration cavity of the variable phase velocity section 111 increases along the movement direction of the electron beam in turn, the radius of the cavity 110 of the first acceleration cavity of the light velocity section 112 reaches the maximum value, and the radius of the cavity 110 of the acceleration cavity of the light velocity section 112 decreases along the movement direction of the electron beam in turn; the length of the cavity 110 of the acceleration cavity of the variable phase velocity section 111 gradually increases along the movement direction of the electron beam, and the length of the cavity 110 of the acceleration cavity of the light velocity section 112 remains unchanged.

[0046] On the basis of the above structure, in the variable phase velocity section 111, the radius of the cavity 110 of the acceleration cavity gradually increases, and the length also gradually increases, which is helpful for the adjustment of the phase velocity and the maintenance of the resonance frequency.

[0047] As a preferred embodiment, the phase velocity βp of the RF field of the variable phase velocity section 111 gradually transitions from 0.54 to 1, and the phase velocity βp of the RF field of the light velocity section 112 is 1.

[0048] Embodiment Two

[0049] Please refer to Figures 1-4 The embodiment provides a linear accelerator, which comprises the acceleration tube 100, the input coupler skew waveguide 200, the output coupler skew waveguide 300, the first drift tube 400 and the second drift tube 500 of embodiment one.

[0050] The input coupler skew waveguide 200 is in communication with the input coupling cavity, and is used for introducing external radio frequency power into the accelerator.

[0051] The output coupler skew waveguide 300 is in communication with the output coupling cavity, and is used for leading out the remaining microwave power.

[0052] The first drift tube 400 is in communication with the input coupling cavity, and is used for providing a channel for the electron beam to enter the acceleration cavity.

[0053] The second drift tube 500 is in communication with the output coupling cavity, and is used for providing a channel for the accelerated electron beam to exit the acceleration cavity.

[0054] While only certain components and embodiments have been described and shown, many modifications and changes can occur to those skilled in the art (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, changes in material, colors, orientations, locations, and the like). Some features are shown in various drawings in different positions and / or at various orientations for purposes of illustration only and not by way of limitation.

[0055] The above embodiments are only preferred embodiments of the present application, and cannot be used to limit the scope of protection of the present application. Any non-essential changes and replacements made by those skilled in the art on the basis of the present application shall fall within the scope of protection of the present application.

Claims

1. An accelerator tube, characterized in that, the accelerator tube is composed of a plurality of accelerating cavities and a plurality of bars; each of the accelerating cavities is welded with one of the bars to form a complete accelerating structure, and all the accelerating structures are welded to form an accelerator tube body, wherein a beam hole is arranged on each of the bars to make all the accelerating cavities communicate with each other to form a complete beam transmission path; wherein the cavity of the first accelerating cavity in the direction of electron beam movement is an input coupling cavity, and the cavity of the last accelerating cavity in the direction of electron beam movement is an output coupling cavity; the accelerator tube body comprises a variable phase velocity section and a light velocity section which are sequentially communicated in the direction of electron beam movement; the variable phase velocity section is used for bunching and phase slipping of the electron beam, and the light velocity section is used for increasing the energy of the electron beam; the input coupling cavity is a cylindrical inner cavity structure, the output coupling cavity is a cylindrical inner cavity structure, and the cavities of the remaining accelerating cavities are composed of two symmetrical bowl-shaped inner cavity structures.

2. The accelerator tube of claim 1, wherein the number of the accelerating cavities is sixty, wherein the cavities of the first to third accelerating cavities in the direction of electron beam movement are mainly used for bunching, the cavities of the fourth to seventh accelerating cavities are mainly used for phase slipping, and the cavities of the eighth to sixtieth accelerating cavities constitute the light velocity section; the cavity of the first accelerating cavity is the input coupling cavity, and the cavity of the sixtieth accelerating cavity is the output coupling cavity.

3. The accelerator tube of claim 2, wherein the total length of the accelerator tube body is 2043.054 mm, and the thickness of the bar is 5.5 mm.

4. The accelerator tube of claim 2, wherein the edge of the beam hole forms an elliptical structure.

5. The accelerator tube of claim 4, wherein the ratio of the major axis to the minor axis of the elliptical structure of the edge of the beam hole is 1.8:

1.

6. The accelerator tube of claim 5, wherein the major axis of the elliptical structure of the edge of the beam hole is 4.95 mm, and the minor axis is 2.75 mm.

7. The accelerator tube of claim 2 wherein, the aperture of the beam hole of all the bars decreases in turn.

8. The accelerator tube of claim 7 wherein, the cavity radius of the accelerating cavities of the variable phase velocity section increases in turn in the direction of electron beam movement, the cavity radius of the first accelerating cavity of the light velocity section reaches a maximum value, and the cavity radius of the accelerating cavities of the light velocity section decreases in turn in the direction of electron beam movement; the cavity length of the accelerating cavities of the variable phase velocity section gradually increases in the direction of electron beam movement, and the cavity length of the accelerating cavities of the light velocity section remains unchanged.

9. The accelerator tube of claim 2 wherein, the phase velocity β of the RF field of the phase-velocity section p gradually transitions from 0.54 to 1, the phase velocity β of the RF field of the light-velocity section p is 1.

10. A linear accelerator characterized by, the accelerator tube, the input coupling inclined waveguide, the output coupling inclined waveguide, the first drift tube and the second drift tube according to any one of claims 1-9; the input coupling inclined waveguide is communicated with the input coupling cavity and is used for introducing external radio frequency power into the accelerator; the output coupling inclined waveguide is communicated with the output coupling cavity and is used for leading out the remaining microwave power; the first drift tube is communicated with the input coupling cavity and is used for providing a channel for the electron beam to enter the accelerating cavity; the second drift tube is communicated with the output coupling cavity and is used for providing a channel for the accelerated electron beam to exit the accelerating cavity.

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