Energy-adjustable electron linear acceleration structure

Abstract

The utility model discloses an energy-adjustable electron linear acceleration structure. An electron beam source is used for providing electron beams; the accelerating tube body comprises a bunching cavity, a plurality of first accelerating cavities and a plurality of second accelerating cavities, and the plurality of first accelerating cavities and the plurality of second accelerating cavities are arranged in a crossed manner; first microwaves are fed into the beam bunching cavity and the multiple first accelerating cavities, the power of the first microwaves is not changed, the beam bunching cavity is used for bunching electron beams generated by the electron beam source to obtain bunched electron beams, and the multiple first accelerating cavities are used for accelerating the bunched electron beams; second microwaves are fed into the multiple second accelerating cavities, the power amplitude and the relative phase difference of the second microwaves are adjusting variables, and the multiple second accelerating cavities are used for accelerating or decelerating the electron beams. The device has the advantages of high acceleration gradient, wide energy adjusting range, continuous adjustability in the energy adjusting range, high capture rate, good energy spectrum and compact structure.

Description

Technical Field

[0001] The utility model relates to the technical field of electron linear acceleration, in particular to an energy-adjustable electron linear acceleration structure. Background Art

[0002] The electron linear accelerator is a device that uses microwave electromagnetic fields to accelerate electrons. The X-rays produced by electron linear accelerator target shooting have broad application prospects, such as medical treatment, irradiation, imaging, etc.

[0003] Usually the output energy of the electron linear accelerator is fixed. However, in practical applications, it is often hoped that the energy of the electron linear accelerator can be adjusted according to demand. In order to meet the requirements of practical applications, various energy modulation methods have emerged one after another. At present, the commonly used energy modulation methods of electron linear accelerators are:

[0004] (1) Change the overall field intensity distribution of the accelerating tube. This is usually achieved by adjusting the microwave power and beam load. This method is relatively simple to implement, but in order to ensure the capture efficiency and beam energy spectrum of the bunching section, the field intensity cannot change too much, so the energy adjustment range is limited.

[0005] (2) Keep the field intensity of the focusing section basically unchanged, and change the field intensity or phase of the light-speed section alone. There are two ways to implement this scheme: one is to feed the focusing section and the light-speed section separately to achieve independent adjustment; the other is to adjust the field intensity ratio or phase relationship between the focusing section and the light-speed section through an energy switch. This method can obtain a relatively large energy adjustment range, but the microwave feeding system is relatively complex and the acceleration structure is relatively long.

[0006] (3) Changing the working mode of the accelerating tube. By adjusting the microwave frequency of the power source, the standing wave accelerating tube can work in different modes, thereby outputting electron beams of different energy levels. This adjustment method does not require an additional microwave feeding system, and the accelerating tube structure is simple. However, this method generally only provides two energy levels, and it is difficult to achieve a high capture rate for electron beams in the low energy level. Utility Model Content

[0007] The utility model aims to solve at least one of the technical problems existing in the prior art. To this end, one purpose of the utility model is to provide an energy-adjustable electron linear acceleration structure, which has a higher acceleration gradient and a wider energy adjustment range, and has the characteristics of continuous adjustment within the energy adjustment range and a higher capture rate, can obtain a better energy spectrum, and has a compact structure.

[0008] The energy-adjustable electron linear acceleration structure according to the embodiment of the utility model comprises:

[0009] An electron beam source, the electron beam source is used to provide an electron beam;

[0010] An accelerating tube body, the accelerating tube body comprising a bunching cavity, a plurality of first accelerating cavities and a plurality of second accelerating cavities, the plurality of first accelerating cavities and the plurality of second accelerating cavities being cross-arranged; the bunching cavity and the plurality of first accelerating cavities are fed with first microwaves of constant and identical power, the bunching cavity is used to bunch the electron beam generated by the electron beam source to obtain a bunched electron beam, the plurality of first accelerating cavities are used to accelerate the bunched electron beam; the plurality of second accelerating cavities are fed with second microwaves of adjustable and identical power amplitude and relative phase difference, the power amplitude and relative phase difference of the second microwaves being adjustment quantities, the plurality of second accelerating cavities are used to accelerate or decelerate the bunched electron beam.

[0011] When the energy-adjustable electron linear acceleration structure of the embodiment of the utility model is working, the electron beam source provides an electron beam to the accelerating tube body by feeding the first microwave into the bunching cavity and the multiple first accelerating cavities and feeding the second microwave into the multiple second accelerating cavities, and the electron beam passes through the bunching cavity, the multiple first accelerating cavities arranged crosswise and the multiple second accelerating cavities in sequence, wherein the bunching cavity bunches the electron beam generated by the electron beam source to obtain a bunched electron beam, and since the power of the first microwave in the bunching cavity is constant, the capture rate and beam energy spectrum of the bunching section can be effectively guaranteed, and since the power of the first microwave in the multiple first accelerating cavities is constant, the first accelerating cavity can accelerate the bunched electron beam, and since the power amplitude and relative phase difference of the second microwave in the multiple second accelerating cavities can be continuously adjusted, the second accelerating cavity can accelerate or decelerate the bunched electron beam, so that the energy-adjustable electron linear acceleration structure of the embodiment of the utility model has a higher acceleration gradient and a wider energy adjustment range, and has the characteristics of continuous adjustment and a higher capture rate within the energy adjustment range.

[0012] In summary, the advantages of the energy-adjustable electron linear acceleration structure of the embodiment of the utility model are: it has a higher acceleration gradient and a wider energy adjustment range, and has the characteristics of continuous adjustment within the energy adjustment range and a higher capture rate, can obtain a better energy spectrum, and has a compact structure.

[0013] In some embodiments, the bunching cavity and the plurality of the first accelerating cavities are connected through a first side-coupling cavity to form a first cavity chain, the first cavity chain is connected to a first coupling waveguide, and the first coupling waveguide is used to feed the first microwave into the first cavity chain; the plurality of the second accelerating cavities are connected through a second side-coupling cavity to form a second cavity chain, the second cavity chain is connected to a second coupling waveguide, and the second coupling waveguide is used to feed the second microwave into the second cavity chain.

[0014] In some embodiments, the number of the bunching cavities is one or more.

[0015] In some embodiments, a first microwave window is disposed at an input end of the first coupling waveguide, and a second microwave window is disposed at an input end of the second coupling waveguide.

[0016] In some embodiments, an ion pump is disposed on the first coupling waveguide and / or the second coupling waveguide.

[0017] In some embodiments, a first power feeding unit is also included, and the first power feeding unit includes a first microwave power source, a power divider and a microwave amplitude and phase adjustment system, the first microwave power source is connected to the power divider, and the power divider is respectively connected to the first coupling waveguide and the second coupling waveguide, wherein the microwave amplitude and phase adjustment system is arranged between the power divider and the second coupling waveguide.

[0018] In some embodiments, the first power feeding unit also includes two first circulators and two first microwave loads, wherein one of the first circulators is arranged between the power divider and the first coupling waveguide, and one of the first microwave loads is connected to one of the first circulators; wherein another of the first circulators is arranged between the microwave amplitude and phase adjustment system and the second coupling waveguide, and wherein another of the first microwave loads is connected to another of the first circulators.

[0019] In some embodiments, a second power feeding unit is also included, and the second power feeding unit includes two second microwave power sources and a microwave power source phase locking adjustment system; one of the second microwave power sources is connected to the first coupling waveguide, and the other second microwave power source is connected to the second coupling waveguide, and the microwave power source phase locking adjustment system is arranged between the two second microwave power sources.

[0020] In some embodiments, the second power feeding unit also includes two second circulators and two second microwave loads, wherein one of the second circulators is arranged between one of the second microwave power sources and the first coupling waveguide, and one of the second microwave loads is connected to one of the second circulators; and another of the second circulators is arranged between another of the second microwave loads and the second coupling waveguide, and another of the second microwave loads is connected to another of the second circulators.

[0021] In some embodiments, when the second microwave power source is a klystron, the microwave power source phase locking adjustment system is a low-level system with two output ports and an adjustable phase difference; when the second microwave power source is a magnetron, the microwave power source phase locking adjustment system is a master-slave phase-locked loop or interlocking loop with a phase shifter.

[0022] Additional aspects and advantages of the present invention will be given in part in the following description, and in part will become apparent from the following description, or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0024] Figure 1 It is a schematic diagram of the energy-adjustable electron linear acceleration structure of the utility model;

[0025] Figure 2 It is a schematic diagram of a hybrid edge-coupled double-chain structure of the utility model;

[0026] Figure 3 is a schematic diagram of a first power feeding unit of the utility model;

[0027] Figure 4 It is a schematic diagram of a second power feeding unit of the present invention.

[0028] Reference numerals:

[0029] Electron beam source 1; accelerating tube body 2; first cavity chain I; second cavity chain II; bunching cavity 201; first accelerating cavity 202; first side coupling cavity 203; first coupling waveguide 204; first microwave window 205; second accelerating cavity 206; second side coupling cavity 207; second coupling waveguide 208; second microwave window 209; ion pump 210; first power feeding unit 3; first microwave power source 301; power divider 302; microwave amplitude and phase adjustment system 303; first circulator 304; first microwave load 305; second power feeding unit 4; second microwave power source 401; microwave power source phase locking adjustment system 402; second circulator 403; second microwave load 404. DETAILED DESCRIPTION

[0030] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0031] Combine the following Figures 1 to 4 To describe the energy-adjustable electron linear acceleration structure of an embodiment of the present utility model.

[0032] like Figure 1 and Figure 2As shown, the energy-adjustable electron linear acceleration structure according to the embodiment of the utility model includes an electron beam source 1 and an acceleration tube body 2.

[0033] Specifically, the electron beam source 1 is used to provide an electron beam, which means that the electron beam source 1 is connected to the accelerating tube body 2 and is used to provide the electron beam to the accelerating tube body 2 .

[0034] The accelerating tube body 2 includes a bunching cavity 201, a plurality of first accelerating cavities 202, and a plurality of second accelerating cavities 206. The plurality of first accelerating cavities 202 and the plurality of second accelerating cavities 206 are all standard cavities, and the plurality of first accelerating cavities 202 and the plurality of second accelerating cavities 206 are arranged crosswise; the bunching cavity 201 and the plurality of first accelerating cavities 202 are fed with first microwaves of constant and identical power, the bunching cavity 201 is used to bunch the electron beam generated by the electron beam source 1 to obtain a bunched electron beam, and the plurality of first accelerating cavities 202 are used to accelerate the bunched electron beam; the plurality of second accelerating cavities 206 are fed with second microwaves of adjustable and identical power amplitude and relative phase difference, and the power amplitude and relative phase difference of the second microwaves are adjustment quantities. It should be noted that the first microwave power of the bunching cavity 201 remains unchanged, which can effectively ensure the capture rate and beam energy spectrum of the bunching section, and the first microwave power of the first accelerating cavity 202 remains unchanged, which can accelerate the bunched electron beam; the power amplitude and relative phase difference of the second microwave are adjustment quantities, wherein the microwave power amplitude can adjust the size of the electric field in the second accelerating cavity 206 and control the energy gain of the bunched electron beam, and the relative phase difference can adjust the acceleration / deceleration relationship of the bunched electron beam in the two adjacent first accelerating cavities 202 and the second accelerating cavity 206, and control the acceleration and deceleration of the bunched electron beam. In addition, a better energy spectrum can be obtained by reasonably configuring the two parameters of power amplitude and relative phase difference; a plurality of first accelerating cavities 202 and a plurality of second accelerating cavities 206 are cross-arranged, which can ensure a better electron beam energy spectrum in a wide energy adjustment range and a more compact structure.

[0035] When the energy adjustable electron linear acceleration structure of the embodiment of the utility model is working, the electron beam source 1 provides an electron beam to the accelerating tube body 2 by feeding the first microwave into the bunching cavity 201 and the multiple first accelerating cavities 202 and feeding the second microwave into the multiple second accelerating cavities 206. The electron beam passes through the bunching cavity 201, the multiple first accelerating cavities 202 arranged crosswise, and the multiple second accelerating cavities 206 in sequence. The bunching cavity 201 bunches the electron beam generated by the electron beam source 1 to obtain a bunched electron beam. Since the power of the first microwave in the bunching cavity 201 remains unchanged, it can effectively ensure The capture rate and beam energy spectrum of the bunching section, since the power of the first microwaves in the multiple first accelerating cavities 202 is unchanged, the first accelerating cavities 202 can accelerate the electron beam, and since the power amplitude and relative phase difference of the second microwaves in the multiple second accelerating cavities 206 can be continuously adjusted, the second accelerating cavities 206 can accelerate or decelerate the electron beam, so that the energy-adjustable electron linear acceleration structure of the embodiment of the utility model has a higher acceleration gradient and a wider energy adjustment range, and has the characteristics of continuous adjustment and a higher capture rate within the energy adjustment range.

[0036] In summary, the advantages of the energy-adjustable electron linear acceleration structure of the embodiment of the utility model are: it has a higher acceleration gradient and a wider energy adjustment range, and has the characteristics of continuous adjustment within the energy adjustment range and a higher capture rate, can obtain a better energy spectrum, and has a compact structure.

[0037] In some embodiments, Figure 1 and Figure 2As shown, the accelerating tube body 2 adopts a hybrid side-coupled double-chain structure. Specifically, the bunching cavity 201 and the plurality of first accelerating cavities 202 are connected through the first side-coupled cavity 203 to form a first cavity chain I. The first side-coupled cavity 203 plays a role in microwave power coupling between adjacent bunching cavities 201, between the bunching cavity 201 and the first accelerating cavity 202, and between adjacent first accelerating cavities 202. The first side-coupled cavity 203 used between adjacent bunching cavities 201 is a common side-coupled cavity, while the first side-coupled cavity 203 between adjacent bunching cavities 201 and the first side-coupled cavity 203 and between adjacent first accelerating cavities 202 are all cross-side coupled cavities. The first cavity chain I is connected to a first coupling waveguide 204, and the first coupling waveguide 204 is used to feed the first microwave to the first cavity chain I; multiple second accelerating cavities 206 are connected through the second side coupling cavity 207 to form a second cavity chain II, and the second side coupling cavity 207 plays a role in microwave power coupling between adjacent second accelerating cavities 206, and the second side coupling cavities 207 between adjacent second accelerating cavities 206 are all cross-side coupling cavities; the second cavity chain II is connected to a second coupling waveguide 208, and the second coupling waveguide 208 is used to feed the second microwave to the second cavity chain II. As a result, the structure is simple and compact, and it is convenient to feed the first microwave to the bunching cavity 201 and multiple first accelerating cavities 202 through the first coupling waveguide 204, and it is convenient to feed the second microwave to multiple second accelerating cavities 206 through the second coupling waveguide 208.

[0038] In some embodiments, there are one or more bunching cavities 201 to complete the bunching process of the DC electron beam. The bunching effect of multiple bunching cavities 201 is better than that of a single bunching cavity 201. If a bunching scheme with multiple bunching cavities 201 is adopted, an ordinary side coupling cavity is used between the bunching cavities 201 as the first side coupling cavity 203 for inter-cavity coupling.

[0039] In some embodiments, a first microwave window 205 is provided at the input end of the first coupling waveguide 204; a second microwave window 209 is provided at the input end of the second coupling waveguide 208; the first microwave window 205 and the second microwave window 209 isolate the internal vacuum of the accelerating tube 2 from the external environment.

[0040] In some embodiments, an ion pump 210 is disposed on the first coupling waveguide 204 and / or the second coupling waveguide 208 . The ion pump 210 can achieve the vacuum degree required in the accelerating tube 2 .

[0041] In some embodiments, Figure 3As shown, it also includes a first power feeding unit 3, which includes a first microwave power source 301, a power divider 302 and a microwave amplitude and phase adjustment system 303. The first microwave power source 301 can be a klystron or a magnetron; the first microwave power source 301 is connected to the power divider 302, and the power divider 302 is respectively connected to the first coupling waveguide 204 and the second coupling waveguide 208, wherein the microwave amplitude and phase adjustment system 303 is arranged between the power divider 302 and the second coupling waveguide 208.

[0042] When the first power feeding unit 3 is working, the microwave output by the first microwave power source 301 is divided into two microwaves through the power divider 302, for example, it can be evenly divided into two microwaves; one of the microwaves keeps the microwave power unchanged and is directly fed into the first coupling waveguide 204 as the first microwave, and the other microwave is fed into the second coupling waveguide 208 as the second microwave after the microwave power amplitude and relative phase difference are adjusted by the microwave amplitude and phase adjustment system 303.

[0043] The first power feeding unit 3 has a simple structure and can make the energy-adjustable electron linear acceleration structure have a higher acceleration gradient and a wider energy adjustment range, and has the characteristics of continuous adjustment and a higher capture rate within the energy adjustment range, so as to obtain a better energy spectrum.

[0044] In some embodiments, the first power feeding unit 3 further includes two first circulators 304 and two first microwave loads 305, wherein one of the first circulators 304 is arranged between the power distributor 302 and the first coupling waveguide 204, and one of the first microwave loads 305 is connected to one of the first circulators 304; wherein another first circulator 304 is arranged between the microwave amplitude and phase adjustment system 303 and the second coupling waveguide 208, and wherein another first microwave load 305 is connected to another of the first circulators 304. By arranging the first circulator 304 and the first microwave load 305, it is possible to prevent the reflected microwave power from returning to the first microwave power source 301, and to input the reflected microwave power into the first microwave load 305.

[0045] In some embodiments, Figure 4 As shown, it also includes a second power feeding unit 4, which includes two second microwave power sources 401 and a microwave power source phase locking adjustment system 402; the two second microwave power sources 401 can both be klystrons or magnetrons, one of the second microwave power sources 401 is connected to the first coupling waveguide 204, and the other second microwave power source 401 is connected to the second coupling waveguide 208, and the microwave power source phase locking adjustment system 402 is arranged between the two second microwave power sources 401.

[0046] When the second power feeding unit 4 is working, the microwave power source phase locking adjustment system 402 makes the microwave output by one of the second microwave power sources 401 have a specific phase difference, and makes the microwave output by another second microwave power source 401 have an adjustable phase difference; the microwave with a specific phase difference output by one of the second microwave power sources 401 is used as the first microwave and fed into the first coupling waveguide 204, and the microwave with an adjustable phase difference output by another second microwave power source 401 is used as the second microwave and fed into the second coupling waveguide 208.

[0047] The second power feed unit 4 has a simple structure and can make the energy-adjustable electron linear acceleration structure have a higher acceleration gradient and a wider energy adjustment range, and has the characteristics of continuous adjustment and a higher capture rate within the energy adjustment range, so as to obtain a better energy spectrum.

[0048] In some embodiments, the second power feeding unit 4 further includes two second circulators 403 and two second microwave loads 404, wherein one second circulator 403 is arranged between one of the second microwave power sources 401 and the first coupling waveguide 204, and one of the second microwave loads 404 is connected to one of the second circulators 403; wherein another second circulator 403 is arranged between another of the second microwave loads 404 and the second coupling waveguide 208, and wherein another of the second microwave loads 404 is connected to another of the second circulators 403. By arranging the second circulator 403 and the second microwave load 404, it is possible to prevent the reflected microwave power from returning to the second microwave power source 401, and to input the reflected microwave power into the second microwave load 404.

[0049] In some embodiments, when the second microwave power source 401 is a klystron, the microwave power source phase locking adjustment system 402 is a low-level system with two output ports and an adjustable phase difference; when the second microwave power source 401 is a magnetron, the microwave power source phase locking adjustment system 402 is a master-slave phase-locked loop or interlocking loop with a phase shifter.

[0050] In the description of the utility model specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In the utility model specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0051] Although the embodiments of the present invention have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. An energy-adjustable electron linear acceleration structure, characterized in that: include: An electron beam source, the electron beam source is used to provide an electron beam; An accelerating tube body, the accelerating tube body comprising a bunching cavity, a plurality of first accelerating cavities and a plurality of second accelerating cavities, the plurality of first accelerating cavities and the plurality of second accelerating cavities being arranged crosswise; the bunching cavity and the plurality of first accelerating cavities are fed with first microwaves of constant power and the same, the bunching cavity is used to bunch the electron beam generated by the electron beam source to obtain a bunched electron beam, and the plurality of first accelerating cavities are used to accelerate the bunched electron beam; The plurality of second accelerating cavities are fed with the same second microwaves with adjustable power amplitude and relative phase difference, and the plurality of second accelerating cavities are used to accelerate or decelerate the bunched electron beam.

2. The energy adjustable electron linear acceleration structure according to claim 1, characterized in that The bunching cavity and the plurality of the first accelerating cavities are connected through a first side coupling cavity to form a first cavity chain, the first cavity chain is connected to a first coupling waveguide, and the first coupling waveguide is used to feed the first microwave into the first cavity chain; the plurality of the second accelerating cavities are connected through a second side coupling cavity to form a second cavity chain, the second cavity chain is connected to a second coupling waveguide, and the second coupling waveguide is used to feed the second microwave into the second cavity chain.

3. The energy-adjustable electron linear acceleration structure according to claim 2, characterized in that: The number of the bunching cavities is one or more.

4. The energy-adjustable electron linear acceleration structure according to claim 2, characterized in that: The input end of the first coupling waveguide is provided with a first microwave window, and the input end of the second coupling waveguide is provided with a second microwave window.

5. The energy-adjustable electron linear acceleration structure according to claim 2, characterized in that: An ion pump is provided on the first coupling waveguide and / or the second coupling waveguide.

6. The energy-adjustable electron linear acceleration structure according to any one of claims 2 to 5, characterized in that: It also includes a first power feeding unit, which includes a first microwave power source, a power divider and a microwave amplitude and phase adjustment system, the first microwave power source is connected to the power divider, and the power divider is respectively connected to the first coupling waveguide and the second coupling waveguide, wherein the microwave amplitude and phase adjustment system is arranged between the power divider and the second coupling waveguide.

7. The energy-adjustable electron linear acceleration structure according to claim 6, characterized in that: The first power feeding unit also includes two first circulators and two first microwave loads, wherein one of the first circulators is arranged between the power divider and the first coupling waveguide, and one of the first microwave loads is connected to one of the first circulators; and another of the first circulators is arranged between the microwave amplitude and phase adjustment system and the second coupling waveguide, and another of the first microwave loads is connected to another of the first circulators.

8. The energy-adjustable electron linear acceleration structure according to any one of claims 2 to 5, characterized in that: It also includes a second power feeding unit, which includes two second microwave power sources and a microwave power source phase locking adjustment system; one of the second microwave power sources is connected to the first coupling waveguide, and the other of the second microwave power sources is connected to the second coupling waveguide, and the microwave power source phase locking adjustment system is arranged between the two second microwave power sources.

9. The energy-adjustable electron linear acceleration structure according to claim 8, characterized in that: The second power feeding unit also includes two second circulators and two second microwave loads, wherein one of the second circulators is arranged between one of the second microwave power sources and the first coupling waveguide, and one of the second microwave loads is connected to one of the second circulators; and another of the second circulators is arranged between another of the second microwave loads and the second coupling waveguide, and another of the second microwave loads is connected to another of the second circulators.

10. The energy-adjustable electron linear acceleration structure according to claim 8, characterized in that: When the second microwave power source is a klystron, the microwave power source phase locking adjustment system is a low-level system with two output ports and an adjustable phase difference; when the second microwave power source is a magnetron, the microwave power source phase locking adjustment system is a master-slave phase-locked loop or an interlocking loop with a phase shifter.

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