阅读说明：本技术 谐振加速腔 (Resonant accelerating cavity ) 是由 李金海 杨誉 吴青峰 朱志斌 于 2020-12-30 设计创作，主要内容包括：一种谐振加速腔,包括：腔体,腔体包括相对设置的上弧形壁部和下弧形壁部、以及相对设置的左壁部和右壁部,上弧形壁部、左壁部、下弧形壁部和右壁部依次连接并围设形成腔室,腔室内具有加速电场,其中,左壁部和右壁部之间的最大距离小于上弧形壁部和下弧形壁部之间的最大距离；一对电极板,一个电极板的一侧与左壁部连接,另一个电极板的一侧与右壁部连接,一对电极板的另外一侧相对设置且形成间隙；两个束流孔道组,分别设置在一对电极板中,两个束流孔道组的束流孔道之间一一对应；左壁部和右壁部上分别设置有与两个束流孔道组的多个束流孔道相连通的多个开孔。上述谐振加速腔,具有优化的腔体形状和尺寸,有助于改善粒子束流加速效果。(A resonant accelerating cavity, comprising: the cavity comprises an upper arc-shaped wall part and a lower arc-shaped wall part which are oppositely arranged, and a left wall part and a right wall part which are oppositely arranged, wherein the upper arc-shaped wall part, the left wall part, the lower arc-shaped wall part and the right wall part are sequentially connected and enclose to form a chamber, and an accelerating electric field is arranged in the chamber, wherein the maximum distance between the left wall part and the right wall part is smaller than the maximum distance between the upper arc-shaped wall part and the lower arc-shaped wall part; one side of one electrode plate is connected with the left wall part, one side of the other electrode plate is connected with the right wall part, and the other sides of the pair of electrode plates are oppositely arranged and form a gap; the two beam pore channel groups are respectively arranged in the pair of electrode plates, and the beam pore channels of the two beam pore channel groups are in one-to-one correspondence; the left wall part and the right wall part are respectively provided with a plurality of openings communicated with the plurality of beam channels of the two beam channel groups. The resonant acceleration cavity has the optimized cavity shape and size, and is beneficial to improving the particle beam acceleration effect.)

1. A resonant accelerating cavity, comprising:

the cavity (30) comprises an upper arc-shaped wall portion (301) and a lower arc-shaped wall portion (302) which are oppositely arranged, and a left wall portion (303) and a right wall portion (304) which are oppositely arranged, wherein the upper arc-shaped wall portion (301), the left wall portion (303), the lower arc-shaped wall portion (302) and the right wall portion (304) are sequentially connected and enclose to form a chamber (306), an accelerating electric field is arranged in the chamber (306), and the maximum distance between the left wall portion (303) and the right wall portion (304) is smaller than the maximum distance between the upper arc-shaped wall portion (301) and the lower arc-shaped wall portion (302);

a pair of electrode plates (31a, 31b) disposed in the chamber (306), one side of one of the electrode plates (31a) being connected to the left wall portion (303), one side of the other of the electrode plates (31b) being connected to the right wall portion (304), the other side of the pair of electrode plates (31a, 31b) being disposed opposite to each other with a gap (311) formed therebetween;

two beam current pore channel groups (32) respectively arranged in the pair of electrode plates (31a, 31b), wherein each beam current pore channel group (32) comprises a plurality of beam current pore channels (320), the plurality of beam current pore channels (320) are arranged at intervals in the corresponding electrode plates (31a, 31b) along the axial direction of the cavity (30), each beam current pore channel (320) penetrates through two sides of the corresponding electrode plates (31a, 31b), the beam current pore channels (320) of the two beam current pore channel groups (32) are in one-to-one correspondence,

the left wall portion (303) and the right wall portion (304) are respectively provided with a plurality of openings (308) communicated with the plurality of beam channels (320) of the two beam channel groups (32), the openings (308) are used for enabling particle beams to enter the cavity (30) or to be emitted out of the cavity (30) through the openings, and when the particle beams pass through the gap (311), the particle beams are accelerated under the action of the accelerating electric field.

2. The resonant acceleration cavity of claim 1,

the left wall portion (303) and/or the right wall portion (304) are flat plate-shaped.

3. The resonant acceleration cavity of claim 1,

the left wall portion (303) and the right wall portion (304) are parallel to each other.

4. The resonant acceleration cavity of claim 3, wherein,

the pair of electrode plates (31a, 31b) is perpendicular to the left wall portion (303).

5. The resonant acceleration cavity of claim 1,

the upper arc-shaped wall part (301) and/or the lower arc-shaped wall part (302) is semicircular in cross section.

6. The resonant acceleration cavity of claim 1,

the shape of the chamber (306) is symmetrical up and down, left and right along the central line thereof.

7. The resonant acceleration cavity of claim 1,

a pair of the electrode plates (31a, 31b) are arranged coplanar.

8. The resonant acceleration cavity of claim 7, wherein,

a pair of the electrode plates (31a, 31b) is located at an intermediate position of the chamber (306).

9. The resonant acceleration cavity of claim 8, wherein,

the cross sections of the upper arc-shaped wall part (301) and the lower arc-shaped wall part (302) are semicircular and have the same size,

the size of the left wall part (303) and the right wall part (304) in the vertical direction is larger than zero and is smaller than or equal to the diameter of a semicircle formed by the section of the upper arc-shaped wall part (301).

10. The resonant acceleration cavity of claim 1,

the electrode plates (31a, 31b) have the same size along the extending direction of the beam current pore passage (320).

11. The resonant acceleration cavity of claim 1,

the motion trail of the particle beam is snakelike and is positioned on the plane of the beam channel group (32).

12. The resonant acceleration cavity of claim 1,

the particle beam has a motion trajectory which is helical and surrounds at least part of the outside of the cavity (30).

13. The resonant acceleration cavity of claim 1,

further comprises sealing members provided at both ends of the cavity (30) in the direction of axial extension to seal the chamber (306).

14. A method for accelerating a particle beam, comprising the steps of:

injecting particle beams into a cavity of the resonant acceleration cavity;

when the particle beam enters the cavity and moves to the gap between the two electrode plates along the beam pore channel, the particle beam is accelerated;

the accelerated particle beam continuously moves along the beam channel and is emitted from the cavity;

the emitted particle beam moves in a deflection way and enters the cavity again to be accelerated again;

the particle beam after multiple times of acceleration is emitted from the resonant acceleration cavity to finish acceleration;

wherein, the cavity comprises an upper arc-shaped wall part and a lower arc-shaped wall part which are oppositely arranged, and a left wall part and a right wall part which are oppositely arranged, the upper arc-shaped wall part, the left wall part, the lower arc-shaped wall part and the right wall part are sequentially connected and enclosed to form a cavity, an accelerating electric field is arranged in the cavity, wherein the maximum distance between the left wall part and the right wall part is smaller than the maximum distance between the upper arc-shaped wall part and the lower arc-shaped wall part,

two of the electrode plates are arranged in the cavity, one side of one of the electrode plates is connected with the left wall part, one side of the other electrode plate is connected with the right wall part, the other sides of the two electrode plates are oppositely arranged and form a gap,

each electrode plate is provided with a plurality of beam current pore passages, the beam current pore passages are arranged in the corresponding electrode plate at intervals along the axis direction of the cavity, each beam current pore passage penetrates through the two corresponding sides of the electrode plate, and the beam current pore passages of the two electrode plates are in one-to-one correspondence.

15. The method of claim 14, wherein,

the particle beam makes snake-shaped motion on the plane of the beam channel.

16. The method of claim 14, wherein,

the particle beam spirally moves around at least part of the outer side of the cavity.

Technical Field

The invention relates to the technical field of accelerators, in particular to a resonant acceleration cavity for accelerating particles.

Background

The existing accelerator types comprise an electron accelerator, which is widely applied to the fields of industry, agriculture, medical irradiation and the like. The electron accelerator can adopt a resonant acceleration cavity, and certain radio frequency power is input into the resonant acceleration cavity to establish an alternating electric field, so that electron beams move in the resonant acceleration cavity and are accelerated under the action of the electric field.

The existing resonant acceleration cavity is mostly a cylindrical cavity, and is characterized in that the diameter of the cavity is large, so that a beam channel is long, and the movement distance of electron beams accelerated twice is difficult to meet the acceleration phase synchronization condition (namely, the electron beams can be ensured to be continuously accelerated). If the problem is solved by reducing the diameter of the cavity, the resonant frequency is increased, and the components such as beam focusing, guiding and measuring arranged around the cavity lack installation space, so that adverse effects are brought to debugging and long-term stable operation of the accelerator.

Disclosure of Invention

To solve at least the above problems, according to one aspect of the present invention, an embodiment of the present invention provides a resonant accelerating cavity, including: the cavity comprises an upper arc-shaped wall part and a lower arc-shaped wall part which are oppositely arranged, and a left wall part and a right wall part which are oppositely arranged, wherein the upper arc-shaped wall part, the left wall part, the lower arc-shaped wall part and the right wall part are sequentially connected and enclose to form a cavity, an accelerating electric field is arranged in the cavity, and the maximum distance between the left wall part and the right wall part is smaller than the maximum distance between the upper arc-shaped wall part and the lower arc-shaped wall part; a pair of electrode plates disposed in the chamber, one side of one of the electrode plates being connected to the left wall portion, one side of the other of the electrode plates being connected to the right wall portion, the other of the electrode plates being disposed opposite to each other with a gap therebetween; the two beam pore channel groups are respectively arranged in the pair of electrode plates, each beam pore channel group comprises a plurality of beam pore channels, the beam pore channels are arranged in the corresponding electrode plates at intervals along the axis direction of the cavity, each beam pore channel penetrates through two corresponding sides of the electrode plates, the beam pore channels of the two beam pore channel groups correspond to one another one by one, a plurality of openings communicated with the beam pore channels of the two beam pore channel groups are respectively arranged on the left wall part and the right wall part, the openings are used for enabling particle beams to enter the cavity or to be emitted out of the cavity through the openings, and when the particle beams pass through the gaps, the particle beams are accelerated under the action of the accelerating electric field.

Further, the left wall portion and/or the right wall portion are flat plate-shaped.

Further, the left wall portion and the right wall portion are parallel to each other.

Further, the pair of electrode plates is perpendicular to the left wall portion.

Further, the cross section of the upper arc-shaped wall part and/or the lower arc-shaped wall part is semicircular.

Further, the shape of the cavity is symmetrical up and down and left and right along the central line of the cavity.

Further, a pair of the electrode plates are disposed coplanar.

Further, a pair of the electrode plates is located at a middle position of the chamber.

Further, the cross sections of the upper arc-shaped wall portion and the lower arc-shaped wall portion are semicircular and equal in size, and the size of the left wall portion and the size of the right wall portion in the vertical direction are larger than zero and smaller than or equal to the diameter of the semicircle formed by the cross section of the upper arc-shaped wall portion.

Further, the electrode plates have the same size along the extending direction of the beam current pore passage.

Furthermore, the motion trail of the particle beam is in a snake shape and is positioned on the plane of the beam channel group.

Further, the particle beam has a motion track which is spiral and surrounds at least part of the outer side of the cavity.

Further, the resonance acceleration cavity further comprises sealing members provided at both end portions of the cavity in the axial extending direction to seal the cavity.

According to another aspect of the present invention, an embodiment of the present invention further provides a method for accelerating a particle beam, including the following steps: injecting particle beams into a cavity of the resonant acceleration cavity; when the particle beam enters the cavity and moves to the gap between the two electrode plates along the beam pore channel, the particle beam is accelerated; the accelerated particle beam continuously moves along the beam channel and is emitted from the cavity; the emitted particle beam moves in a deflection way and enters the cavity again to be accelerated again; the particle beam after multiple times of acceleration is emitted from the resonant acceleration cavity to finish acceleration; wherein, the cavity includes relative last arc wall portion and lower arc wall portion that sets up and relative left wall portion and right wall portion that sets up, go up arc wall portion, left side wall portion, arc wall portion and right wall portion connect gradually and enclose and establish and form the cavity down, the accelerating electric field has in the cavity, wherein, the maximum distance between left side wall portion and the right wall portion is less than go up arc wall portion and the maximum distance between the arc wall portion down, two the electrode plate sets up in the cavity, one side of one the electrode plate with left wall portion is connected, another one side of electrode plate with right wall portion is connected, the relative clearance that sets up and form in the other side of two the electrode plate, every electrode plate sets up a plurality of beam pore canals, a plurality of beam pore canals are in corresponding electrode plate along the axis direction interval arrangement of cavity, each beam pore passage penetrates through two sides of the corresponding electrode plate, and the beam pore passages of the two electrode plates are in one-to-one correspondence.

Further, the particle beam makes snake-shaped motion on the plane where the beam channel is located.

Further, the particle beam spirals around at least part of the outside of the cavity.

According to the resonant acceleration cavity disclosed by the embodiment of the invention, the moving distance of the electron beam accelerated twice can meet the acceleration phase synchronization condition by optimizing the shape and size of the cavity of the resonant acceleration cavity, meanwhile, the beam components are convenient to mount around the cavity, and favorable conditions are provided for debugging and long-term stable operation of the acceleration cavity.

Drawings

Other objects and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings, and may assist in a comprehensive understanding of the invention.

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention.

Fig. 1 is a schematic diagram of a resonant accelerating cavity in the prior art.

Fig. 2 is a schematic cross-sectional view of the resonant acceleration cavity of fig. 1.

Fig. 3 is a schematic structural diagram of a resonant acceleration cavity according to one embodiment of the present invention.

Fig. 4 is a schematic cross-sectional view of the resonant acceleration cavity of fig. 3.

Fig. 5 is a schematic diagram of the distribution of the electromagnetic field used by the resonant acceleration cavity of fig. 3.

Description of reference numerals:

the chambers 10, 30; electrode plates 11a, 11b, 31a, 31 b; a beam channel group 32; beam ports 120, 320; an upper arc-shaped wall portion 301; a lower arcuate wall portion 302; a left wall portion 303; a right wall portion 304; a chamber 306; an opening 308; the gap 311; an electric field 90; a magnetic field 80.

It is noted that the drawings are not necessarily to scale and are merely illustrative in nature and not intended to obscure the reader.

Detailed Description

In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs.

The resonant acceleration cavity provided by the embodiment of the invention can realize the function of an electron accelerator and support the acceleration of electron beams. By optimizing the shape and size of the cavity of the resonant acceleration cavity, on one hand, the electron beam can be ensured to be continuously accelerated in the acceleration cavity, and the installation of beam components and devices and the debugging of the acceleration cavity are facilitated, and the beam output intensity is improved; on the other hand, the radio frequency quality factor can be improved, and the radio frequency loss is reduced; on the other hand, the cavity structure is facilitated to be simplified, the mechanical processing is facilitated, and the stability of the mechanical structure is improved.

The resonant accelerating cavity provided by the embodiment of the invention can be improved aiming at the structure of the existing cylindrical resonant accelerating cavity (hereinafter referred to as cylindrical resonant cavity). As shown in fig. 1 or 2, a conventional cylindrical resonant cavity generally includes a cylindrical cavity 10, ridge-type electrode plates 11a and 11b disposed in the cavity, and beam channels 120 disposed in the electrode plates. The particle beam is injected into the cavity 10, moves along the beam channel 120, is accelerated under the action of an electric field in the cavity 10, and is ejected from the acceleration cavity after the acceleration is completed. The particle beam is, for example, an electron beam.

The particle beam is accelerated multiple times in the resonant cavity to obtain the desired particle energy. The particle beam can make spiral motion or snake motion relative to the resonant cavity. Fig. 2 shows the trajectory of the serpentine particle beam (indicated by the dashed line).

Referring to fig. 1, under a certain resonant frequency, the diameter of the cavity of the cylindrical resonant cavity is large, so that the corresponding beam pore channel is long, and therefore, it is difficult to make the moving distance of the two adjacent accelerated particle beams satisfy the acceleration phase synchronization condition. The acceleration phase synchronization refers to a path that a particle beam moving from the center of the acceleration gap is ejected from the acceleration cavity, deflected by 180 degrees and then enters the acceleration cavity to move to the center of the acceleration gap, wherein the path is equal to half of the wavelength of a radio frequency field in vacuum, namely the diameter of a cavity of a resonant cavity is required to be less than half of the wavelength of the radio frequency field in vacuum, namely the length of a beam channel in an electrode plate is required to be less than one fourth of the wavelength of the radio frequency field in vacuum. Because the beam channel is long, and the particle beam needs to deflect 180 degrees after being accelerated and emitted out of the cavity for one time so as to enter the cavity again, the path of the particle beam moving in the beam channel and the path of the particle beam deflecting and moving outside the cavity are difficult to meet the acceleration phase synchronization condition. On the basis, if the diameter of the cavity is reduced so as to reduce the length of the beam channel to overcome the problem, the resonant frequency is correspondingly increased, and the radio frequency wavelength is reduced at the moment, and in this case, the movement path of the particle beam may still fail to meet the above condition. Once again, even if the above conditions are met, the reduction in the diameter of the cavity results in a corresponding reduction in the available space around the cavity, which is detrimental to the mounting of the beam components (e.g., for components used to deflect particles, turning of the tube requires a certain turning radius and mechanical space in the engineering).

In addition, the long length of the beam channel also easily causes the large transverse envelope of the particle beam in the transmission process, which leads to the loss of beam intensity/density, thus being not beneficial to the improvement of beam output intensity or power.

In view of the above, it is necessary to optimize the shape and size of the cavity of the cylindrical resonant cavity, and by optimizing the mechanical parameters, the moving distance of the two adjacent accelerated particle beams can satisfy the acceleration phase synchronization condition while the resonant frequency is unchanged, and at the same time, the intensity/power of the output particle beam is improved.

Referring to fig. 3 to 5, the resonant acceleration cavity according to the embodiment of the present invention uses a resonant cavity different from the above-mentioned cylindrical cavity, which includes a cavity 30, a pair of electrode plates 31a, 31b, and a beam channel group 32/beam channels 320. The working principle of the resonant cavity is the same as that of the cylindrical resonant cavity, and the particle beam is continuously accelerated under the action of an alternating electric field established by the resonant cavity and finally emitted from the accelerating cavity.

The cavity 30 comprises an upper arc-shaped wall part 301 and a lower arc-shaped wall part 302 which are oppositely arranged, and a left wall part 303 and a right wall part 304 which are oppositely arranged, wherein the upper arc-shaped wall part 301, the left wall part 303, the lower arc-shaped wall part 302 and the right wall part 304 are sequentially connected and enclose to form a chamber 306, and an accelerating electric field is arranged in the chamber 306, wherein the maximum distance between the left wall part 303 and the right wall part 304 is smaller than the maximum distance between the upper arc-shaped wall part 301 and the lower arc-shaped wall part 302. As shown in fig. 1 and 3, the cavity 30 can reduce the maximum distance between the left wall 303 and the right wall 304 while improving the shape of the cavity compared with the existing cylindrical cavity 10, so as to shorten the moving path of the particle beam in the cavity, i.e. reduce the length of the beam channel.

Further, a pair of electrode plates 31a and 31b are provided in the chamber 306, one side of one electrode plate 31a is connected to the left wall portion 303, one side of the other electrode plate 31b is connected to the right wall portion 304, and the other sides of the pair of electrode plates 31a and 31b are disposed to face each other with a gap 311 formed therebetween.

The electrode plate is a metal electrode plate and is used for building a cross-over variable electric field in the resonant cavity. In some embodiments, the electromagnetic field mode established within the resonant cavity is TE₁₁₀As shown in fig. 5, the electric field 90 is distributed primarily between the gap formed by the two electrode plates, and the magnetic field 80 is spatially distributed within the chamber around the two electrode plates. The direction of the electric field is parallel to the paper and the direction of the magnetic field comprises components parallel to the paper and perpendicular to the paper. Acceleration is obtained when the particle beam moves to the gap between the two electrode plates.

Further, the two beam path sets 32 are respectively disposed in the pair of electrode plates 31a and 31b, each beam path set 32 includes a plurality of beam paths 320, the plurality of beam paths 320 are arranged at intervals in the corresponding electrode plates 31a and 31b along the axial direction of the cavity 30, each beam path 320 penetrates through two sides of the corresponding electrode plates 31a and 31b, and the beam paths 320 of the two beam path sets 32 are in one-to-one correspondence. The beam channel group 32/beam channel 320 is used for transmitting the particle beam, and in order to accelerate the particle beam in the resonant cavity for multiple times, a plurality of beam channels 320 are provided, and the arrangement direction of the plurality of beam channels 320 is along the axial direction of the cavity 30, so that the particle beam can perform overall snake-like motion or spiral motion, and fig. 2 shows the snake-like motion trajectory of the particle beam. The beam channels 320 of the two beam channel groups 32 have the same channel size and are aligned, which is beneficial to the efficient transmission of particle beams.

Further, the left wall 303 and the right wall 304 are respectively provided with a plurality of openings 308 communicated with the plurality of beam ducts 320 of the two beam duct groups 32, and the openings 308 are used for enabling the particle beam to enter the cavity 30 or to exit the cavity 30 through the openings 308.

In some embodiments, the acceleration chamber has a more optimized chamber shape and/or size. As shown in fig. 3, the resonant acceleration cavity 300a further optimizes the shape of the left wall 303 and/or the right wall 304. The left wall portion 303 and/or the right wall portion 304 may have a flat plate shape. Such a configuration is very advantageous for machining, and also for mounting of the electrode plates, since one side of the electrode plates 31a, 31b is connected to the left wall portion 303 and the right wall portion 304, respectively.

When the left wall portion 303 and the right wall portion 304 each have a flat plate shape, the left wall portion 303 and the right wall portion 304 may be further parallel to each other. At this time, the distance between the left wall portion 303 and the right wall portion 304 is uniform.

Further, the electrode plates 31a, 31b may be provided to be installed perpendicularly to the left and right wall portions 303, 304, respectively.

The shape of the left wall 303 and/or the right wall 304 may be a curved surface or an irregular plane, and may be set according to actual requirements.

In some embodiments, the resonant acceleration cavity 300a further optimizes the shape of the upper and/or lower curved wall portions 301, 302. The upper and/or lower arcuate wall portions 301, 302 may be semi-circular in cross-section. Such a configuration makes it easy to determine the dimensions of the arc, and based on that, the dimensions of the cavity 30, which in turn affects the resonant frequency, the radio frequency quality factor, etc.

The radio frequency quality factor, also known as the Q value, reflects the relationship between the resonant cavity energy storage and loss. The resonant accelerating cavity provided by the embodiment of the invention can realize the purpose of improving the Q value under the condition of optimizing the shape and size of the cavity. By increasing the Q value, the accelerating electric field established at the same rf power loss on the cavity wall of the resonant cavity is made higher, thereby optimizing particle acceleration.

To further understand the Q value, the description is made in conjunction with the shape and size of the resonant cavity.

As shown in fig. 3 or 4, the electrode plates 31a and 31b divide the interior of the chamber 30 into upper and lower two-part spaces. Taking the upper space or the lower space as an example, when the cross-sectional area defined by the semicircular cavity wall, the left cavity wall, the right cavity wall and the two electrode plates is constant and the circumference of the composition is smaller, the Q value can be higher. In particular, the Q value is related to cavity wall loss (cavity wall loss is related to resistivity, path through which current flows, etc.). When the cross-sectional area is constant, the smaller the circumference formed by the cavity wall through which the current flows, the smaller the cavity wall loss, and the Q value increases accordingly. Alternatively, it is also understood that when the perimeter formed by the cavity wall through which the current flows is constant, the larger the cross-sectional area is, the higher the Q value is.

However, in the cavity configuration in fig. 1, it is difficult to satisfy the above conditions to improve the Q value. As shown in fig. 3 or 4, the overall shape of the cavity 30 according to the embodiment of the present invention is approximately racetrack-shaped, and on the basis, the Q value is improved by optimizing the size of the cavity 30.

As shown in fig. 4, the resonance acceleration chamber 300b has a chamber body 30, and the upper arc-shaped wall portion 301 and the lower arc-shaped wall portion 302 are each semicircular in cross section and equal in size, while the left wall portion 303 and the right wall portion 304 are each flat plate-shaped and equal in size.

Further, the electrode plates 31a, 31b are disposed perpendicularly to the left wall portion 303 and the right wall portion 304, and the electrode plates 31a, 31b are disposed at the middle position of the chamber 306 such that the chamber 306 is vertically symmetrical with respect to the electrode plates 31a, 31 b. The thicknesses of the two electrode plates 31a, 31b may be uniform such that the two electrode plates 31a, 31b are disposed coplanar along a horizontal plane.

As can be seen from the above, it is advantageous to increase the Q value if the circumference surrounded by the upper and lower chamber walls is made smaller or the cross-sectional area surrounded by the upper and lower chamber walls is made larger, with the plane where the electrode plates 31a and 31b are located as a boundary (ignoring the thickness of the electrode plates). As shown in fig. 4, when the radius of the semicircular cavity wall is R and the size of the flat cavity wall in the vertical direction is H, the Q value can be increased as much as possible when a certain relationship is satisfied between H and R.

Assuming that the perimeter of the upper/lower partial cavity wall enclosure is C and the cross-sectional area of the upper/lower partial cavity wall enclosure is S, H can be further expressed as:

H＝C-πR-2αR------------------------------------------------------(1)

in the formula (1), α R (0 ≤ α ≤ 1) represents the length of the beam channel in one electrode plate.

Further, S can be represented as:

S＝HR+πR²/2＝CR-πR²/2-2αR²----------------------------------------(2)

assuming that C is constant, to make S larger, it should be satisfied:

dS/dR＝0----------------------------------------------------------(3)

calculated according to the above formulas (1) to (3):

R＝C/(π+4α)-------------------------------------------------------(4)

the compound represented by formula (4) is substituted for formula (1):

H＝2Cα/(π+4α)-----------------------------------------------------(5)

further, by comparing the formula (4) and the formula (5), the relationship between H and R is:

H＝2αR------------------------------------------------------------(6)

that is, when the relationship of the above formula (6) is satisfied between H and R, the Q value can be increased as much as possible. That is, the dimensions of the left wall portion 303 and the right wall portion 304 in the vertical direction are made larger than zero and equal to or smaller than the diameter of the semicircle formed by the cross section of the upper arc-shaped wall portion 301.

As shown in fig. 4, in some embodiments, when the size of the gap 311 between the electrode plates 31a and 31b is small relative to the length dimension of the beam passage 320 (i.e., the dimension of the beam passage 320 in the extending direction), α in the above equation (6) may be 1, and the relationship between H and R may be:

H＝2R-------------------------------------------------------------(7)

thus, in the embodiment of fig. 4, the cross-sectional shape of the cavity 30 is: the upper and lower parts are two semicircles, and the middle part connected with the upper and lower semicircles is rectangular or square.

From the above, by optimizing the shape and size of the cavity 30, compared with the cylindrical cavity 10, under the condition that the diameter of the cavity is reduced and thus the length of the beam channel 320 is reduced, it can be ensured that the moving distance of the electron beam accelerated twice adjacent to each other meets the acceleration phase synchronization condition. Further optimizing the sizes of H and R is also beneficial to improving the Q value.

It should be noted that the length of the beam passage 320 is a dimension of the beam passage 320 in the extending direction, and may also be understood as a width dimension of the electrode plates 31a and 31 b.

In some embodiments, the two electrode plates 31a and 31b have equal width dimensions, so that the moving distance of two adjacent accelerated electron beams easily satisfies the acceleration phase synchronization condition.

In some embodiments, the particle beam may have a serpentine or spiral motion profile. When the particle beam has a serpentine motion trajectory, a duct for guiding and deflecting the particle beam, which is communicated with the opening 308, may be disposed at the outer side of the left wall 303 and the right wall 304 of the cavity 30 near the opening 308, so that the particle beam performs a 180-degree deflection motion at this position. When the particle beam has a spiral motion trajectory, a member for focusing, guiding, and deflecting the particle beam may be disposed around at least a portion of the cavity 30 to assist the particle beam in making a spiral motion.

In some embodiments, the resonant acceleration cavity 300a/300b may further include sealing members disposed at both ends of the cavity 30 in the axial extension direction to seal the cavity 306, so that a sealed space is formed in the cavity 30, in which a vacuum pump or the like may be used to provide a vacuum environment required for the particle beam to move. The sealing member is, for example, a flange assembly.

The Q values that can be obtained for the optimized cavities are described below with reference to specific embodiments. Taking the resonant accelerating cavity 300b shown in fig. 4 as an example, different Q values can be obtained according to different mechanical parameter optimizations.

Example 1:

the mechanical parameters are as follows: the resonance frequency was 100MHz, the gap between the electrode plates 31a, 31b was 200mm in size, the length of the cavity 30 (i.e., the dimension extending in the axial direction) was 2m, and R was 341 mm.

The Q value was calculated to be 50000 based on the above mechanical parameters.

Example 2:

the mechanical parameters are as follows: the resonance frequency was 100MHz, the gap between the electrode plates 31a, 31b was 80mm in size, the length of the cavity 30 (i.e., the dimension extending in the axial direction) was 2m, and R was 265 mm.

The Q value was 37000 calculated from the above mechanical parameters.

The cavity 30 of the embodiment of the present application has a higher Q value than the cylindrical cavity 10 (in this configuration, it can obtain a Q value of about 30000).

According to another aspect of the present invention, an embodiment of the present invention further provides a method for accelerating a particle beam, including the following steps: injecting particle beams into a cavity of the resonant acceleration cavity; when the particle beam enters the cavity and moves to the gap between the two electrode plates along the beam pore channel, the particle beam is accelerated; the accelerated particle beam continuously moves along the beam channel and is emitted from the cavity; the emitted particle beam moves in a deflection way and enters the cavity again to be accelerated again; the particle beam after multiple times of acceleration is emitted from the resonant acceleration cavity to finish acceleration; wherein the cavity comprises an upper arc-shaped wall part and a lower arc-shaped wall part which are oppositely arranged, and a left wall part and a right wall part which are oppositely arranged, the upper arc-shaped wall part, the left wall part, the lower arc-shaped wall part and the right wall part are sequentially connected and enclosed to form a chamber, an accelerating electric field is arranged in the chamber, the maximum distance between the left wall and the right wall is smaller than the maximum distance between the upper arc-shaped wall and the lower arc-shaped wall, the two electrode plates are arranged in the cavity, one side of one electrode plate is connected with the left wall, one side of the other electrode plate is connected with the right wall, the other sides of the two electrode plates are oppositely arranged and form a gap, each electrode plate is provided with a plurality of beam channels, the beam channels are arranged in the corresponding electrode plate at intervals along the axis direction of the cavity, each beam channel penetrates through the two sides of the corresponding electrode plate, and the beam channels of the two electrode plates are in one-to-one correspondence.

In some embodiments, the particle beam moves in a serpentine shape in a plane in which the beam channel is located.

In some embodiments, the particle beam spirals around the outside of at least part of the cavity.

The above method can be implemented based on the resonant acceleration cavity in fig. 3 or 4 for accelerating e.g. an electron beam current.

The resonant accelerating cavity in fig. 3 or 4 has improved cavity shape and size, which is beneficial to improving the output intensity and power of particle beam and improving the beam transmission effect.

For the description of the structure of the acceleration cavity and the process of the particle beam movement, the same contents and technical effects can be referred to the foregoing, and are not described herein again.

It should also be noted that, in the case of the embodiments of the present invention, features of the embodiments and examples may be combined with each other to obtain a new embodiment without conflict.

The above description is only an embodiment of the present invention, but the scope of the present invention is not limited thereto, and the scope of the present invention is subject to the scope of the claims.