Standing wave accelerating tube and accelerating device

Abstract

The invention provides a standing wave accelerating tube and an accelerating device, and relates to the technical field of accelerator equipment. According to the standing wave accelerating tube, the electron beam energy can be adjusted in a wide range, and the beam current loss of the electron beam can be reduced. The standing wave accelerating tube comprises an accelerating tube body, and the accelerating tube body is provided with a beam bunching cavity and an accelerating cavity set. Wherein the beam bunching cavity is communicated with the outer wall of the accelerating tube body through a beam inlet, and the beam bunching cavity is used for generating a focusing electric field in the radial direction of the beam inlet and an accelerating electric field in the axial direction of the beam inlet; the accelerating cavity assembly comprises at least two accelerating cavities, the at least two accelerating cavities are distributed in the axial direction of the beam inlet and are sequentially communicated, one of the at least two accelerating cavities adjacent to the beam bunching cavity is communicated with the beam bunching cavity, the beta value of the cavity of the accelerating cavity assembly is equal to 1, and the accelerating cavity assembly is used for generating an electric field in the axial direction.

Description

Technical Field

[0001] The present application relates to but is not limited to the technical field of accelerator equipment, and in particular to a standing wave accelerating tube and an accelerating device. Background Art

[0002] Electron accelerators are widely used in fields such as X-ray imaging, irradiation processing, and safety inspection. The acceleration structure is the core component of the electron accelerator. The electrons emitted by the electron gun are accelerated to the required energy through the acceleration structure to carry out irradiation applications or convert them into X-rays for imaging or detection.

[0003] The continuously adjustable energy of electron accelerators makes the accelerators more widely applicable. In the related art, the electron beam is decelerated and the energy of the electron beam is reduced by changing the magnitude or phase of the electric field in the acceleration structure. Although this method can reduce the energy of the electron beam, it is easy to cause a large electron beam current loss, and the range of adjusting the energy of the electron beam is limited. Summary of the invention

[0004] The present application provides a standing wave accelerating tube and an accelerating device, which can adjust the electron beam energy within a wide range and reduce the electron beam current loss.

[0005] On the one hand, the present application provides a standing wave accelerating tube, which comprises: an accelerating tube body, the accelerating tube body having a focusing cavity and an accelerating cavity group. The focusing cavity is connected to the outer wall of the accelerating tube body through a beam inlet, and the focusing cavity is used to generate a focusing electric field along the radial direction of the beam inlet and an accelerating electric field along the axial direction of the beam inlet; the accelerating cavity group comprises at least two accelerating cavities, at least two accelerating cavities are distributed along the axial direction of the beam inlet and are connected in sequence, one of the at least two accelerating cavities adjacent to the focusing cavity is connected to the focusing cavity, the cavity β value of the accelerating cavity group is equal to 1, and the accelerating cavity assembly is used to generate an electric field along the axial direction.

[0006] The standing wave accelerating tube provided by the present application, because a bunching cavity is provided in the accelerating tube body, the low-energy electron beam generated by the electron gun can be accelerated by the bunching cavity, and the electron beam can be longitudinally bunched and transversely focused by the bunching cavity, which is conducive to making the electron beam move in the accelerating tube according to a preset path. In addition, an accelerating cavity group adjacent to the bunching cavity is provided in the accelerating tube body, and the accelerating cavity group is set to include at least two accelerating cavities, and the cavity β value of the accelerating cavity group is 1. In the process of accelerating the electron beam by the accelerating cavity group, the electric field amplitude of one accelerating cavity in the accelerating cavity group can be changed, while the electric field amplitudes of the bunching cavity and other accelerating cavities in the accelerating cavity group are kept unchanged, so that the output energy of the electron beam can be continuously adjusted while maintaining the bunching effect on the electron beam. At the same time, the transverse electric field in the accelerating cavity group (the electric field along the radial direction of the beam inlet) has a focusing effect, and the accelerating cavity group composed of at least two accelerating cavities can enhance the focusing effect on the electron beam compared with a single accelerating cavity, thereby reducing the beam loss of the electron beam, which is conducive to reducing the size of the exit beam spot.

[0007] Therefore, compared with the related art, although adjusting the electric field of a single accelerating cavity can adjust the energy of the electron beam within a certain range, it is easy to cause a large electron beam current loss. The standing wave accelerating tube provided in the present application can adjust the electron beam energy within a wider range while reducing the electron beam current loss.

[0008] In a possible implementation of the present application, the accelerating chamber group includes a first accelerating chamber and a second accelerating chamber, wherein the first accelerating chamber is located in the accelerating tube body close to the focusing chamber, and the second accelerating chamber is located in the accelerating tube body far from the focusing chamber.

[0009] In a possible implementation of the present application, the cavity β value of the first accelerating cavity is greater than the cavity β value of the second accelerating cavity.

[0010] In a possible implementation of the present application, the accelerating tube body further has a waveguide channel, the focusing cavity and each accelerating cavity are respectively connected to the corresponding waveguide channel, and the waveguide channel is used to connect to the waveguide.

[0011] In a possible implementation of the present application, the accelerating tube body has at least two accelerating cavity groups, which are sequentially distributed on the same side of the focusing cavity along the axial direction of the beam inlet, and two adjacent accelerating cavities in two adjacent accelerating cavity groups are connected.

[0012] In a possible implementation of the present application, the waveguide channel includes a first waveguide channel and a second waveguide channel, the focusing cavity and each second accelerating cavity are connected to the first waveguide channel, and each first accelerating cavity is connected to the second waveguide channel.

[0013] In a possible implementation of the present application, along the radial direction of the beam inlet, the first waveguide channel and the second waveguide channel are respectively located on two opposite sides of the accelerating tube body.

[0014] In a possible implementation of the present application, the accelerating tube body has at least two focusing cavities, and the at least two focusing cavities are located on the same side of the accelerating cavity group in the accelerating tube body.

[0015] In a possible implementation of the present application, each bunching cavity is connected to the same waveguide channel; or, two spaced bunching cavities are connected to the same waveguide channel.

[0016] On the other hand, the present application provides an accelerating device, which includes: an electron gun and a standing wave accelerating tube provided by any one of the above items, wherein the electron gun is connected to a beam inlet of the standing wave accelerating tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the structure of a standing wave accelerating tube provided in an embodiment of the present application;

[0018] Figure 2 A schematic cross-sectional view of the structure of the standing wave accelerating tube provided in the embodiment of the present application Figure 1 ;

[0019] Figure 3 A schematic cross-sectional view of the structure of the standing wave accelerating tube provided in the embodiment of the present application Figure 2 ;

[0020] Figure 4 A schematic diagram of the high-energy electric field distribution of the standing wave accelerating tube provided in an embodiment of the present application;

[0021] Figure 5 A schematic diagram of the low-energy electric field distribution of the standing wave accelerating tube provided in an embodiment of the present application.

[0022] Description of reference numerals:

[0023] 1-accelerating tube body; 11-bunching cavity; 12-accelerating cavity group; 121-first accelerating cavity; 122-second accelerating cavity; 13-waveguide channel; 131-first waveguide channel; 132-second waveguide channel; 133-coupling port; 14-beam inlet; X-radial; Y-axial. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the specific technical solution of the present application will be further described in detail below in conjunction with the drawings in the embodiments of the present application. The following embodiments are used to illustrate the present application, but are not used to limit the scope of the present application.

[0025] In the embodiments of the present application, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, unless otherwise specified, "multiple" means two or more.

[0026] In addition, in the embodiments of the present application, directional terms such as "up", "down", "left" and "right" are defined relative to the orientation of the components in the drawings. It should be understood that these directional terms are relative concepts. They are used for relative description and clarification, and they may change accordingly according to the changes in the orientation of the components in the drawings.

[0027] In the embodiments of the present application, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium.

[0028] In the embodiments of the present application, the terms "include", "comprises" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0029] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0030] An electron accelerator is a type of charged particle accelerator. It is a resonant accelerator that uses high microwave power to establish a longitudinal electric field in a traveling wave or standing wave acceleration structure to accelerate an electron beam. Electron accelerators are widely used in the fields of radiographic imaging, irradiation processing, safety inspection, etc. The acceleration structure is the core component of an electron accelerator. The electrons emitted by an electron gun can be accelerated to the required energy through the acceleration structure, so that the material can be irradiated by a high-energy electron beam to carry out irradiation applications, or the high-energy electron beam can be bombarded on a conversion target to generate X-rays, so that X-rays can be used for imaging or detection.

[0031] The electron accelerator's continuously adjustable energy makes it widely applicable. On the one hand, in irradiation applications, an electron beam with appropriate energy can be selected according to the thickness of the irradiated object. On the other hand, in applications such as X-ray imaging, since X-rays of different energies have different penetration depths, the most appropriate energy of X-rays can be selected according to the thickness of the object being measured (the higher the energy of the electron beam, the higher the energy of the X-rays generated) for imaging or detection. For example, for workpieces with complex structures and uneven thickness, more comprehensive information about the workpiece can be obtained by combining the X-ray detection results of different energies.

[0032] In the related art, the energy-continuously adjustable acceleration structure of the electron accelerator usually divides the acceleration process into two stages, the front and back stages, and the electron beam is decelerated by changing the magnitude of the accelerating electric field in the back stage to reduce the energy gain in the back stage, or by changing the phase of the accelerating electric field in the back stage, so as to reduce the energy of the electron beam. Since the electron beam flow is slowly accelerated or continuously decelerated in the back stage, rather than synchronously accelerated, this easily causes a large electron beam flow loss, and this method has a limited range of adjustment for the electron beam energy.

[0033] On this basis, the present application embodiment provides a standing wave accelerating tube, referring to Figure 1 , Figure 2 and Figure 3 , Figure 1 This is a schematic diagram of the structure of the standing wave accelerating tube provided in the embodiment of the present application. Figure 2 A schematic cross-sectional view of the structure of the standing wave accelerating tube provided in the embodiment of the present application Figure 1 , Figure 3 A schematic cross-sectional view of the structure of the standing wave accelerating tube provided in the embodiment of the present application Figure 2 The standing wave accelerating tube comprises: an accelerating tube body 1, wherein the accelerating tube body 1 has a focusing cavity 11 and an accelerating cavity group 12. The focusing cavity 11 is connected to the outer wall of the accelerating tube body 1 through a beam inlet 14, and the focusing cavity 11 is used to generate a focusing electric field along the radial direction X of the beam inlet 14 and an accelerating electric field along the axial direction Y of the beam inlet 14; the accelerating cavity group 12 comprises at least two accelerating cavities, and at least two accelerating cavities are distributed along the axial direction Y of the beam inlet 14 and are connected in sequence, and at least one of the two accelerating cavities adjacent to the focusing cavity 11 is connected to the focusing cavity 11, and the cavity β value of the accelerating cavity group 12 is equal to 1, and the accelerating cavity group 12 is used to generate an electric field along the axial direction Y.

[0034] In the embodiment of the present application, the accelerating tube body 1 can be made of materials such as copper, and the accelerating tube body 1 can be set as two plane-symmetrical parts, and structures such as the focusing cavity 11 and the accelerating cavity group 12 can be processed on each part, and then the two parts can be buckled together to obtain the standing wave accelerating tube provided in the embodiment of the present application.

[0035] In the embodiment of the present application, the focusing cavity 11 is used to accelerate the low-energy electron beam emitted by the electron gun to a speed close to the speed of light, and can make the electron beam passing through the focusing cavity 11 converge in the direction close to the axis of the focusing cavity 11 to reduce the radius of the electron beam and achieve lateral focusing of the electron beam. It can also reduce the length of each pulse bunch in the electron beam and achieve longitudinal focusing of the electron beam, so that the electron beam moves along a preset trajectory.

[0036] For example, Figure 2 and Figure 3 As shown, a beam inlet 14 can be provided on the accelerating tube body 1 , and the beam inlet 14 can be provided as a through hole matching the electron gun. For example, the beam inlet 14 can be a cylindrical through hole, and one end of the beam inlet 14 is located on the outer surface of the accelerating tube body 1 .

[0037] In another example, the focusing cavity 11 can be arranged at one end of the accelerating tube close to the beam inlet 14, and the beam inlet 14 is connected to the focusing cavity 11. For example, the focusing cavity 11 can be arranged as a cavity approximately in a cylindrical shape, and the focusing cavity 11 and the beam inlet 14 are arranged coaxially. Along the axial direction Y of the beam inlet 14, the width of the focusing cavity 11 can be set to 25 mm to 35 mm, and along the radial direction X of the beam inlet 14, the diameter of the focusing cavity 11 can be set to 70 mm to 80 mm.

[0038] In the embodiment of the present application, the accelerating cavity group 12 is used to accelerate the electron beam emitted from the focusing cavity 11 so that the electron beam obtains the required energy. Radio frequency power can be fed into the accelerating cavity group 12 to generate an accelerating electric field along the axial direction Y of the beam inlet 14 in the accelerating cavity to accelerate the electron beam.

[0039] Exemplarily, the accelerating cavity group 12 can be set to a structure including multiple accelerating cavities, and multiple accelerating cavities form one accelerating cavity group 12, and the cavity β value of the accelerating cavity group 12 (the β value of the accelerating cavity group 12) is 1, that is, the sum of the cavity β values ​​of the multiple accelerating cavities in the same accelerating cavity group 12 is 1. The cavity β value represents the relative phase velocity of the electromagnetic wave in the cavity, that is, the ratio of the phase velocity to the speed of light. Usually, in order to achieve matching acceleration of particles by the electromagnetic field, the cavity β value of a single accelerating cavity is basically close to or consistent with the ratio of the electron velocity in the cavity to the speed of light. The sum of the cavity β values ​​of the multiple accelerating cavities in the accelerating cavity group 12 is 1, and the whole can match and accelerate electron beams close to the speed of light. In this way, different RF powers can be fed to different accelerating cavities in the same accelerating cavity group 12, so that different acceleration electric fields of different intensities can be established in different accelerating cavities in the same accelerating cavity group 12.

[0040] Another example, such as Figure 2 and Figure 3As shown, the multiple accelerating cavities in the accelerating cavity group 12 can be sequentially distributed in the accelerating tube body 1 along the axial direction Y of the beam inlet 14. The multiple accelerating cavities in the same accelerating cavity group 12 are connected to facilitate the movement of the electron beam. For example, the accelerating cavity adjacent to the bunching cavity 11 can be connected to the bunching cavity 11, so that the electron beam in the bunching cavity 11 can enter the adjacent accelerating cavity.

[0041] In another example, the accelerating cavity may be set as a cavity approximately in a cylindrical shape, and the accelerating cavity may be coaxially arranged with the beam inlet 14. The size of the corresponding accelerating cavity may be set according to the cavity β values ​​of different accelerating cavities in the same accelerating cavity group 12. For example, along the axial direction Y of the beam inlet 14, different values ​​may be set for the widths of different accelerating cavities in the same accelerating cavity group 12, so that different accelerating cavities in the same accelerating cavity group 12 have different cavity β values.

[0042] The standing wave accelerating tube provided in the embodiment of the present application has a focusing cavity 11 in the accelerating tube body 1, so that the low-energy electron beam generated by the electron gun can be accelerated by the focusing cavity 11, and the electron beam can be longitudinally focused and transversely focused by the focusing cavity 11, which is conducive to making the electron beam move in the accelerating tube according to a preset path. In addition, an accelerating cavity group 12 adjacent to the focusing cavity 11 is provided in the accelerating tube body 1, and the accelerating cavity group 12 is configured to include at least two accelerating cavities, and the cavity β value of the accelerating cavity group is 1. In the process of accelerating the electron beam by the accelerating cavity group 12, the electric field amplitude of one accelerating cavity in the accelerating cavity group 12 can be changed, while the electric field amplitudes of the focusing cavity 11 and other accelerating cavities in the accelerating cavity group 12 are kept unchanged, so that the output energy of the electron beam can be continuously adjusted while maintaining the focusing effect on the electron beam. At the same time, the transverse electric field in the accelerating cavity group 12 (the electric field along the radial direction X of the beam inlet 14) has a focusing effect. Compared with a single accelerating cavity, the accelerating cavity group composed of at least two accelerating cavities can enhance the focusing effect on the electron beam, thereby reducing the beam loss of the electron beam and helping to reduce the size of the exit beam spot.

[0043] Therefore, compared with the related art, although adjusting the electric field of a single accelerating cavity can adjust the energy of the electron beam within a certain range, it is easy to cause a large electron beam current loss. The standing wave accelerating tube provided in the embodiment of the present application can adjust the electron beam energy within a wider range while reducing the electron beam current loss.

[0044] In some possible embodiments of the present application, Figure 2 and Figure 3As shown, the accelerating chamber group 12 includes a first accelerating chamber 121 and a second accelerating chamber 122 . The first accelerating chamber 121 is located in the accelerating tube body 1 close to the focusing chamber 11 , and the second accelerating chamber 122 is located in the accelerating tube body 1 far from the focusing chamber 11 .

[0045] In the embodiment of the present application, the accelerating chamber group 12 can be configured to include a structure of two accelerating chambers. That is, one accelerating chamber group 12 includes a first accelerating chamber 121 and a second accelerating chamber 122. For example, the first accelerating chamber 121 in the same accelerating chamber group 12 can be located in a position close to the focusing chamber 11 in the accelerating tube body 1, and the second accelerating chamber 122 can be located in a position far from the focusing chamber 11 in the accelerating tube body 1.

[0046] Exemplarily, the cavity β value of the first accelerating cavity 121 may be set to be greater than the cavity β value of the second accelerating cavity 122. The cavity β value of the first accelerating cavity 121 may also be set to be less than the cavity β value of the second accelerating cavity 122. Alternatively, the cavity β value of the first accelerating cavity 121 may also be set to be equal to the cavity β value of the second accelerating cavity 122.

[0047] In the above embodiment, since the accelerating cavity group 12 is configured to include a first accelerating cavity 121 and a second accelerating cavity 122, not only can the electric field amplitudes of the two accelerating cavities be adjusted individually to facilitate continuous adjustment of the energy of the electron beam, but also when the accelerating cavity group 12 includes two accelerating cavities, it is convenient to adjust the electric field amplitude of one of the accelerating cavities.

[0048] In some possible embodiments of the present application, Figure 2 and Figure 3 As shown, the cavity β value of the first accelerating cavity 121 is greater than the cavity β value of the second accelerating cavity 122 .

[0049] In the embodiment of the present application, the cavity β value of the first accelerating cavity 121 can be set to be greater than the cavity β value of the second accelerating cavity 122, so that the first accelerating cavity 121 has a longer acceleration time for the electron beam, while the second accelerating cavity 122 continues to accelerate and focus the electron beam.

[0050] Exemplarily, when the operating frequency of the accelerating cavity group 12 is 2998 MHz, the cavity β value of the first accelerating cavity 121 can be 0.7, and the cavity β value of the second accelerating cavity 122 can be 0.3. Along the axial direction Y of the beam inlet 14, the width of the first accelerating cavity 121 can be set to 35 mm, and the width of the second accelerating cavity 122 can be set to 15 mm. Alternatively, the cavity β value of the first accelerating cavity 121 can be 0.6, and the cavity β value of the second accelerating cavity 122 can be 0.4. Along the axial direction Y of the beam inlet 14, the width of the first accelerating cavity 121 can be set to 30 mm, and the width of the second accelerating cavity 122 can be set to 20 mm.

[0051] In another example, the wall thickness between two adjacent accelerating cavities can be set to 2 mm to 5 mm, for example, the wall thickness between the first accelerating cavity 121 and the second accelerating cavity 122 can be set to 2 mm, 3 mm, 4 mm, or 5 mm, etc. Along the radial direction X of the beam inlet 14, the diameters of the first accelerating cavity 121 and the second accelerating cavity 122 can be set to 70 mm-80 mm. For example, the diameters of the first accelerating cavity 121 and the second accelerating cavity 122 are both set to 70 mm, 72 mm, 75 mm, 78 mm, or 80 mm, etc.

[0052] In another example, a truncated cone-shaped nose cone can be provided in each accelerating cavity, and each accelerating cavity has two opposite nose cones, and the ends with smaller diameters of the two opposite nose cones are close to each other. The axis of the nose cone is coaxial with the axis of the accelerating cavity. By providing the nose cone, the electric field in each accelerating cavity can be concentrated near the axis of the accelerating cavity between the nose cones.

[0053] In the above embodiment, since the cavity β value of the first accelerating cavity 121 is greater than the cavity β value of the second accelerating cavity 122, along the axial direction Y of the beam inlet 14, the length of the first accelerating cavity 121 can be made greater than the length of the second accelerating cavity 122, and the movement time of the electron beam in the first accelerating cavity 121 can be made greater than the movement time in the second accelerating cavity 122, so that in the process of adjusting the electric field strength in the first accelerating cavity 121, the energy of the electron beam can have a larger adjustment range.

[0054] In some possible embodiments of the present application, Figure 2 and Figure 3 As shown, the accelerating tube body 1 also has a waveguide channel 13, and the focusing cavity 11 and each accelerating cavity are respectively connected to the corresponding waveguide channel 13, and the waveguide channel 13 is used to connect with the waveguide.

[0055] In the embodiment of the present application, a waveguide channel 13 may be provided in the accelerating tube body 1 to transmit radio frequency power to the focusing cavity 11 and each accelerating cavity through the waveguide channel 13 .

[0056] For example, a waveguide channel 13 may be provided for the bunching cavity 11, and an independent waveguide channel 13 may be provided for each accelerating cavity in the accelerating cavity group 12. The bunching cavity 11 and the first accelerating cavity 121 may share the same waveguide channel 13. The bunching cavity 11 and the second accelerating cavity 122 may also share the same waveguide channel 13.

[0057] In another example, the waveguide channel 13 may be set as a blind hole with a rectangular cross section, and the waveguide channel 13 is adjacent to the corresponding bunching cavity 11 and / or the accelerating cavity, and a coupling port 133 may be set between the waveguide channel 13 and the bunching cavity 11 and the accelerating cavity. For example, the coupling port 133 may be set as a through hole with an approximately rectangular cross section, so that the corresponding waveguide channel 13 and the bunching cavity 11 are connected through the coupling port 133, and the corresponding waveguide channel 13 and the accelerating cavity are connected through the coupling port 133. In this way, the bunching cavity 11 and each accelerating cavity can be connected to the waveguide channel 13 separately.

[0058] As another example, the shape of the waveguide channel 13 may be set to a structure matching the waveguide, so as to facilitate connecting the waveguide to the waveguide channel 13 .

[0059] In the above embodiment, since the waveguide channel 13 is provided in the accelerating tube body 1, it is convenient to feed the radio frequency power into the bunching cavity 11 and each accelerating cavity through the waveguide channel 13. And the bunching cavity 11 and each accelerating cavity are respectively connected with the corresponding waveguide channel 13, so that there is no coupling between the bunching cavity 11 and each accelerating cavity, so that the radio frequency power can be separately coupled and fed into the bunching cavity 11 and each accelerating cavity, so that the bunching cavity 11 and each accelerating cavity can work at the same frequency, which is beneficial to reduce the interference between the bunching cavity 11 and each accelerating cavity, and is beneficial to improve the stability of the operation of the standing wave accelerating tube.

[0060] In some possible embodiments of the present application, Figure 2 and Figure 3 As shown, the accelerating tube body 1 has at least two accelerating cavity groups 12, which are sequentially distributed on the same side of the focusing cavity 11 along the axial direction Y of the beam inlet 14, and two adjacent accelerating cavities in two adjacent accelerating cavity groups 12 are connected.

[0061] In the embodiment of the present application, a plurality of accelerating cavity groups 12 may be provided in the accelerating tube body 1. For example, along the axial direction Y of the beam inlet 14, at least two accelerating cavity groups 12 may be arranged in sequence on the same side of the focusing cavity 11.

[0062] Exemplarily, when the accelerating cavity group 12 includes the first accelerating cavity 121 and the second accelerating cavity 122, the first accelerating cavity 121 and the second accelerating cavity 122 can be alternately distributed on the same side of the focusing cavity 11. A through hole for electron beam movement can be provided between the second accelerating cavity 122 and the first accelerating cavity 121 in two adjacent accelerating cavity groups 12, so that two adjacent accelerating cavities in two adjacent accelerating cavity groups 12 are connected.

[0063] In another example, each accelerating cavity in the plurality of accelerating cavity groups 12 may be coaxially arranged with the beam inlet 14. For example, two accelerating cavity groups 12, three accelerating cavity groups 12, or more accelerating cavity groups 12 may be arranged in the standing wave accelerating tube, and the specific number of the accelerating cavity groups 12 is not limited in the embodiment of the present application.

[0064] In the above embodiment, since there are at least two accelerating chamber groups 12 in the accelerating tube body 1, the lateral focusing effect on the electron beam can be enhanced by increasing the number of accelerating chamber groups 12, thereby better reducing the loss of the electron beam flow and reducing the size of the exit beam spot.

[0065] In some possible embodiments of the present application, Figure 2 and Figure 3 As shown, the waveguide channel 13 includes a first waveguide channel 131 and a second waveguide channel 132 , the focusing cavity 11 and each second accelerating cavity 122 are connected to the first waveguide channel 131 , and each first accelerating cavity 121 is connected to the second waveguide channel 132 .

[0066] In the embodiment of the present application, when the accelerating cavity group 12 includes a first accelerating cavity 121 and a second accelerating cavity 122, and the standing wave accelerating tube has multiple accelerating cavity groups 12, each first accelerating cavity 121 can be connected to the same waveguide channel 13, and each second accelerating cavity 122 can be connected to another waveguide channel 13.

[0067] Exemplarily, when the first accelerating cavity 121 in the accelerating cavity group 12 is located near the bunching cavity 11, and the second accelerating cavity 122 is located far away from the bunching cavity 11, the same first waveguide channel 131 can be provided for the bunching cavity 11 and each second accelerating cavity 122, and the same second waveguide channel 132 can be provided for each first accelerating cavity 121. That is, the first waveguide channel 131 and the second waveguide channel 132 are provided on the accelerating tube body 1, and a coupling port 133 is provided between the bunching cavity 11 and the first waveguide channel 131, and a coupling port 133 is provided between each second accelerating cavity 122 and the first waveguide channel 131. And a coupling port 133 is provided between each first accelerating cavity 121 and the second waveguide channel 132.

[0068] In the above embodiment, since each first accelerating cavity 121 is connected to the second waveguide channel 132, the electric field amplitude in each first accelerating cavity 121 can be adjusted synchronously by adjusting the RF power fed into the second waveguide channel 132, and the electric field amplitude in each first accelerating cavity 121 can be made to have the same strength. At the same time, the focusing cavity 11 and each second accelerating cavity 122 are connected to the second waveguide channel 132, and the electric field amplitude in the focusing cavity 11 and each second accelerating cavity 122 can be adjusted synchronously by adjusting the RF power fed into the first waveguide channel 131, and the electric field amplitude in each first accelerating cavity 121 can be made to have the same strength.

[0069] In some possible embodiments of the present application, Figure 2 and Figure 3 As shown, along the radial direction X of the beam inlet 14 , the first waveguide channel 131 and the second waveguide channel 132 are respectively located on two opposite sides of the accelerating tube body 1 .

[0070] In the embodiment of the present application, the first waveguide channel 131 and the second waveguide channel 132 can be arranged as far apart as possible in the accelerating tube body 1. For example, along the radial direction X of the beam inlet 14, the first waveguide channel 131 and the second waveguide channel 132 can be respectively located on opposite sides of the accelerating tube body 1.

[0071] Exemplarily, along the radial direction X of the beam entrance 14 , the first waveguide channel 131 and the second waveguide channel 132 can be located on the same diameter of the beam entrance 14 , so that the first waveguide channel 131 and the second waveguide channel 132 can be located on opposite sides of the radial direction X of the focusing cavity 11 .

[0072] In the above embodiment, since the first waveguide channel 131 and the second waveguide channel 132 are respectively located on opposite sides of the accelerating tube body 1 along the radial direction X of the beam inlet 14, the first waveguide channel 131 and the second waveguide channel 132 can have a larger spacing in the accelerating tube body 1, thereby reducing the mutual influence between the radio frequency powers respectively fed into the first waveguide channel 131 and the second waveguide channel 132.

[0073] In some possible embodiments of the present application, the accelerating tube body 1 has at least two focusing cavities 11 , and the at least two focusing cavities 11 are located on the same side of the accelerating cavity group 12 in the accelerating tube body 1 .

[0074] In the embodiment of the present application, a plurality of focusing cavities 11 may be provided in the accelerating tube body 1, and the plurality of focusing cavities 11 may be connected in sequence. For example, along the axial direction Y of the beam inlet 14, two, three, or four focusing cavities 11 may be provided between the beam inlet 14 and the accelerating cavity group 12, and the plurality of focusing cavities 11 may be adjacent to each other in sequence.

[0075] For example, along the axial direction Y of the beam inlet 14, the width of each beam-forming cavity 11 can be set to 25 mm to 35 mm, such as the width of the beam-forming cavity 11 can be 25 mm, 28 mm, 30 mm, 32 mm or 35 mm, etc.; along the radial direction X of the beam inlet 14, the diameter of each beam-forming cavity 11 can be set to 70 mm-80 mm, such as the diameter of the beam-forming cavity 11 can be 70 mm, 72 mm, 75 mm, 77 mm or 80 mm, etc. Alternatively, the plurality of beam-forming cavities 11 can be set to approximately cylindrical cavities with different widths. The specific structure of the plurality of beam-forming cavities 11 is not limited in the present embodiment.

[0076] In the above embodiment, since a plurality of focusing cavities 11 are provided in the accelerating tube body 1, the low-energy electron beam can be accelerated and focused multiple times in sequence through the plurality of focusing cavities 11, which is beneficial to improving the convergence degree of the electron beam and reducing the beam spot size of the electron beam.

[0077] In some possible embodiments of the present application, each beam-forming cavity 11 is connected to the same waveguide channel 13 ; or, two spaced beam-forming cavities 11 are connected to the same waveguide channel 13 .

[0078] In the embodiment of the present application, when a plurality of focusing cavities 11 are provided in the accelerating tube body 1, the plurality of focusing cavities 11 can be connected to the waveguide channel 13 in different ways.

[0079] Exemplarily, multiple bunching cavities 11 and multiple second accelerating cavities 122 may be connected to the first waveguide channel 131 , or multiple bunching cavities 11 and multiple first accelerating cavities 121 may be connected to the second waveguide channel 132 , so that multiple bunching cavities 11 are connected to the same waveguide channel 13 .

[0080] In another example, along the axial direction Y of the beam inlet 14, two spaced bunching cavities 11 can be connected to the same waveguide channel 13, that is, two adjacent bunching cavities 11 can be connected to different waveguide channels 13. For example, the first bunching cavity 11 adjacent to the first accelerating cavity 121 can be connected to the first waveguide channel 131, the second bunching cavity 11 adjacent to the first bunching cavity 11 can be connected to the second waveguide channel 132, and the third bunching cavity 11 adjacent to the second bunching cavity 11 and far away from the first bunching cavity 11 can be connected to the first waveguide channel 131.

[0081] In the above embodiment, since each bunching cavity 11 is connected to the same waveguide channel 13, the electric field in the multiple bunching cavities 11 can be synchronously adjusted by adjusting the RF power fed into the waveguide channel 13. When two spaced bunching cavities 11 are connected to the same waveguide channel 13, the electric fields in the multiple bunching cavities 11 can be controlled separately, which is conducive to improving the flexibility of accelerating and focusing the electron beam.

[0082] The following is an explanation of the application of the standing wave accelerating tube provided in the embodiment of the present application, referring to Figure 4 and Figure 5 , Figure 4 A schematic diagram of the high-energy electric field distribution of a standing wave accelerating tube provided in an embodiment of the present application, Figure 5 A schematic diagram of the low-energy electric field distribution of the standing wave accelerating tube provided in an embodiment of the present application. Figure 4 and Figure 5 The abscissa in represents the position of the focusing cavity 11 and each accelerating cavity in the accelerating tube body 1, and the ordinate represents the electric field amplitude in the corresponding focusing cavity 11 and accelerating cavity.

[0083] like Figure 4 As shown, when the standing wave accelerating tube provided in the embodiment of the present application is used to accelerate a low-energy electron beam to a higher energy, for example, to accelerate the electron beam to 3MeV, a relatively large RF power can be fed into both the first waveguide channel 131 and the second waveguide channel 132, so that an accelerating electric field can be provided in the bunching cavity 11 and each accelerating cavity. Then, when the electron beam passes through the bunching cavity 11 and each accelerating cavity in turn, the electron beam can be continuously accelerated to accelerate the electron beam to a higher energy.

[0084] like Figure 5 As shown, when the standing wave accelerating tube provided in the embodiment of the present application is used to accelerate the low-energy electron beam to a lower energy, for example, the electron beam is accelerated to 0.5 MeV. At this time, the RF power fed into the second waveguide channel 132 can be reduced, and the electric field amplitude in each first accelerating cavity 121 with a larger cavity β value can be changed, while the accelerating electric field in the bunching cavity 11 and the second accelerating cavity 122 with a smaller cavity β value remains unchanged. When the electron beam passes through the bunching cavity 11, the electron beam can still be accelerated and bunched normally, but after the electron beam enters the accelerating cavity group 12 from the bunching cavity 11, the energy obtained by the electron beam when passing through the first accelerating cavity 121 will be reduced due to the reduction of the electric field amplitude in the first accelerating cavity 121 in each accelerating cavity group 12. Therefore, by adjusting the RF power fed into the second waveguide channel 132, it is possible to accelerate the electron beam to different energies.

[0085] In addition, an embodiment of the present application further provides an accelerating device, which includes: an electron gun and a standing wave accelerating tube provided by any one of the above embodiments.

[0086] In the embodiment of the present application, the electron gun is used to generate an electron beam flow, and the electron gun can be connected to the beam inlet 14 of the standing wave accelerating tube so that the electron beam flow generated by the electron gun enters the standing wave accelerating tube, and the electron beam is accelerated by the standing wave accelerating tube.

[0087] The accelerating device provided in the embodiment of the present application includes the standing wave accelerating tube provided in any one of the above embodiments. Therefore, while adjusting the electron beam energy within a wider range, the electron beam current loss can be reduced.

[0088] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent pipe or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A standing wave accelerating tube, characterized in that: include: An accelerating tube body, wherein the accelerating tube body comprises a focusing cavity and an accelerating cavity group; The focusing cavity is connected to the outer wall of the accelerating tube body through a beam inlet, and the focusing cavity is used to generate a focusing electric field along the radial direction of the beam inlet and an accelerating electric field along the axial direction of the beam inlet; The accelerating cavity group includes at least two accelerating cavities, at least two of which are distributed along the axial direction of the beam inlet and are connected in sequence, at least one of the two accelerating cavities adjacent to the bunching cavity is connected to the bunching cavity, the cavity β value of the accelerating cavity group is equal to 1, and the accelerating cavity assembly is used to generate an electric field along the axial direction.

2. The standing wave accelerating tube according to claim 1, characterized in that: The accelerating chamber group comprises a first accelerating chamber and a second accelerating chamber, wherein the first accelerating chamber is located in the accelerating tube body close to the focusing chamber, and the second accelerating chamber is located in the accelerating tube body far from the focusing chamber.

3. The standing wave accelerating tube according to claim 2, characterized in that: The cavity β value of the first accelerating cavity is greater than the cavity β value of the second accelerating cavity.

4. The standing wave accelerating tube according to claim 2, characterized in that: The accelerating tube body also has a waveguide channel. The focusing cavity and each accelerating cavity are respectively communicated with the corresponding waveguide channel. The waveguide channel is used to connect with the waveguide.

5. The standing wave accelerating tube according to claim 4, characterized in that: The accelerating tube body has at least two accelerating cavity groups, which are sequentially distributed on the same side of the focusing cavity along the axial direction of the beam inlet, and two adjacent accelerating cavities in two adjacent accelerating cavity groups are connected.

6. The standing wave accelerating tube according to claim 5, characterized in that: The waveguide channel includes a first waveguide channel and a second waveguide channel. The bunching cavity and each of the second accelerating cavities are communicated with the first waveguide channel, and each of the first accelerating cavities is communicated with the second waveguide channel.

7. The standing wave accelerating tube according to claim 6, characterized in that: Along the radial direction of the beam inlet, the first waveguide channel and the second waveguide channel are respectively located on two opposite sides of the accelerating tube body.

8. The standing wave accelerating tube according to any one of claims 4 to 7, characterized in that: The accelerating tube body has at least two focusing cavities, and the at least two focusing cavities are located on the same side of the accelerating cavity group in the accelerating tube body.

9. The standing wave accelerating tube according to claim 8, characterized in that: Each of the bunching cavities is connected to the same waveguide channel; Alternatively, the two spaced-apart bunching cavities are connected to the same waveguide channel.

10. An acceleration device, characterized in that: include: Electron gun; The standing wave accelerating tube according to any one of claims 1 to 9, wherein the electron gun is connected to a beam inlet of the standing wave accelerating tube.

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