Standing-wave electron acceleration structure with single-cycle π mode

Abstract

The present invention discloses a standing-wave electron acceleration structure of a single-cycle π mode, which includes an anode cavity, a bunching cavity, a first light-speed cavity, a coupling cavity and an end cavity arranged in sequence, and an acceleration channel is formed at the center of each cavity, and cylindrical coupling holes are provided between adjacent cavities; the bunching cavity is used to form electron bunches from the electrons passing through the anode cavity; the first light-speed cavity is used to accelerate the electrons forming bunches; the coupling cavity is connected to an external magnetron; it operates in the π mode. Compared with the acceleration structure of the π / 2 mode in the traditional technology, since the spatial harmonics in the standing-wave echo also have the effect of accelerating electrons, the purpose of enabling the standing wave to have a higher characteristic impedance in the π mode and enabling the acceleration mechanism to have a higher acceleration gradient is achieved.

Description

Technical Field

[0001] The present invention relates to the field of applications of electron linear accelerators, and particularly to a standing-wave electron acceleration structure of a single-cycle π mode applicable to irradiation and medical electron linear accelerators. Background Art

[0002] Electron linear accelerators are widely used in medical radiotherapy, industrial irradiation sterilization, etc. At present, most of the widely used electron linear accelerators are standing-wave linear accelerators with a double-cycle structure. This acceleration structure operates in the π / 2 mode, and the characteristic impedance of this operating mode is average, and it is impossible to further improve the acceleration efficiency of the accelerator.

[0003] Therefore, how to further improve the acceleration efficiency is a problem to be solved at the present stage.

[0004] The information disclosed in this background art section is only intended to deepen the understanding of the overall background art of the present invention, and should not be regarded as an admission or any form of implication that this information constitutes the prior art known to those skilled in the art. Summary of the Invention

[0005] To solve the above technical problems, the present invention proposes a standing-wave electron acceleration structure of a single-cycle π mode, so as to achieve the purpose of making the standing wave have a higher characteristic impedance in the π mode and making the acceleration mechanism have a higher acceleration gradient.

[0006] To achieve the above purpose, the technical solution of the present invention is as follows:

[0007] A standing-wave electron acceleration structure of a single-cycle π mode includes an anode cavity, a bunching cavity, a first light-speed cavity, a coupling cavity, and an end cavity arranged in sequence, and an acceleration channel is formed at the center of each cavity, and cylindrical coupling holes are provided between adjacent cavities;

[0008] The bunching cavity is used to form electron bunches from the electrons passing through the anode cavity;

[0009] The first light-speed cavity is used to speed up the electrons forming bunches;

[0010] The coupling cavity is connected to an external magnetron.

[0011] The standing-wave electron acceleration structure of a single-cycle π mode proposed by the present invention operates in the π mode. Compared with the acceleration structure in the π / 2 mode in the traditional technology, since the spatial harmonics in the standing-wave echo also have the effect of accelerating electrons, the purpose of making the standing wave have a higher characteristic impedance in the π mode and making the acceleration mechanism have a higher acceleration gradient is achieved.

[0012] Preferably, a second light-speed cavity is provided between the coupling cavity and the end cavity, and the second light-speed cavity is used to speed up the electrons passing through the coupling cavity.

[0013] Preferably, four cylindrical coupling holes are provided between adjacent cavities, and the four cylindrical coupling holes are evenly distributed in a circle around the acceleration channel. The diameter of the cylindrical coupling hole is larger than the diameter of the acceleration channel.

[0014] The present invention has the following advantages:

[0015] 1. The single-period π-mode standing-wave electron acceleration structure proposed by the present invention operates in the π mode. Compared with the acceleration structure in the π / 2 mode in the traditional technology, since the spatial harmonics in the standing-wave echo also have the effect of accelerating electrons, the standing wave has a higher characteristic impedance in the π mode and the acceleration mechanism has a higher acceleration gradient. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art.

[0017] Figure 1 It is a schematic structural diagram of the single-period π-mode standing-wave electron acceleration structure disclosed in the embodiment of the present invention;

[0018] Figure 2 It is a front view schematic diagram of the single-period π-mode standing-wave electron acceleration structure disclosed in the embodiment of the present invention;

[0019] Figure 3 For this Figure 2 The sectional view in the D-D direction;

[0020] The corresponding component names represented by the numbers and letters in the figure:

[0021] 1. Anode cavity 2. Beam bunching cavity 3. First light speed cavity 4. Coupling cavity 5. Second light speed cavity 6. End cavity

[0022] 7. Acceleration channel 8. Cylindrical coupling hole. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention.

[0024] The present invention provides a single-period π-mode standing-wave electron acceleration structure, which operates in the π mode. Compared with the acceleration structure in the π / 2 mode in the traditional technology, since the spatial harmonics in the standing-wave echo also have the effect of accelerating electrons, the standing wave has a higher characteristic impedance in the π mode and the acceleration mechanism has a higher acceleration gradient.

[0025] The present invention will be further described in detail below with reference to the embodiments and the specific implementation manners.

[0026] As shown Figures 1 - 3 in the figure, a standing-wave electron acceleration structure of a single-cycle π mode includes an anode cavity 1, a bunching cavity 2, a first light-speed cavity 3, a coupling cavity 4, a second light-speed cavity 5, and an end cavity 6 (collectively referred to as the acceleration cavity) arranged in sequence. An acceleration channel 7 is formed at the center of each cavity, and cylindrical coupling holes 8 are provided between adjacent cavities;

[0027] The bunching cavity is used to form electron bunches from the electrons passing through the anode cavity;

[0028] The first light-speed cavity and the second light-speed cavity are used to speed up the electrons forming bunches;

[0029] The coupling cavity is connected to an external magnetron.

[0030] The specific usage steps of the present invention are as follows: Again, as shown Figure 1 and Figure 2 in the figure, the present invention adopts a single-cycle structure, and adjacent acceleration cavities are directly coupled, and it operates in the π mode through frequency adjustment. A total of four cylindrical coupling channels are symmetrically placed in the vertical and horizontal directions of the acceleration channel to meet the requirements of power coupling of the acceleration cavity (at the same time, those skilled in the art can increase or decrease the number of acceleration cavities according to the requirements of the required accelerated electron energy).

[0031] Electrons are incident from the left side of the anode cavity 1 by an electron gun. The electrons form bunches after passing through the bunching cavity 2, and then are accelerated through the first light-speed cavity 3. When the electrons pass through the light-speed cavity, their energy approaches the speed of light. Then they enter the coupling cavity 4 (the coupling cavity 4 is connected to an external magnetron or klystron, and the external power is injected into the accelerator through the coupling cavity). The coupled electrons enter the second light-speed cavity 5 for further acceleration, and finally are emitted from the end cavity 6 at the end of the acceleration structure. The electron acceleration process in the π mode is completed.

[0032] As shown Figure 3 in the figure, due to the small radius of the acceleration channel 7, its resonance frequency is lower than the cut-off frequency of the acceleration cavity, and microwave power cannot be transmitted. Therefore, power is transmitted through 4 externally added symmetric cylindrical coupling holes 8. The radius of the cylindrical coupling holes should be larger than the radius of the acceleration channel to make the resonance frequency higher than the cut-off frequency and meet the requirements of the electron acceleration structure.

[0033] The present invention provides a standing-wave electron linear accelerator structure with a single-cycle structure. The accelerator operates in the π mode, and adjacent two acceleration cavities are connected by four symmetric coupling holes with a phase difference of π, which can meet the requirement that electrons always maintain forward acceleration, and this working mode has a relatively high characteristic impedance, which can improve the acceleration efficiency of the accelerator.

[0034] The above are only the preferred embodiments of the standing-wave electron acceleration structure of the single-cycle π mode disclosed in the present invention. It should be noted that for those of ordinary skill in the art, without departing from the inventive concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A standing-wave electron acceleration structure with a single-cycle π mode, characterized in that, it includes an anode cavity, a bunching cavity, a first light-speed cavity, a coupling cavity and an end cavity arranged in sequence, and an acceleration channel is formed at the center of each cavity. Cylindrical coupling holes are provided between adjacent cavities; four cylindrical coupling holes are provided between adjacent cavities, and the four cylindrical coupling holes are evenly distributed in a circle around the acceleration channel. The diameter of the cylindrical coupling hole is larger than the diameter of the acceleration channel; the bunching cavity is used to form electron bunches from the electrons passing through the anode cavity; the first light-speed cavity is used to increase the speed of the electrons forming bunches; the coupling cavity is connected to an external magnetron; a second light-speed cavity is provided between the coupling cavity and the end cavity, and the second light-speed cavity is used to increase the speed of the electrons passing through the coupling cavity.

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