Drift tube linear accelerator

Abstract

The present application relates to the technical field of ion accelerator, in particular to a drift tube type linear accelerator. The linear accelerator comprises: a cavity cylinder, which is a shell structure with a cavity inside; a drift tube, which is a square tube with open slots at both ends; a first cross beam and a second cross beam arranged in the cavity; wherein a plurality of drift tubes are arranged along the central axis of the cavity cylinder at intervals, the first cross beam and the second cross beam are both provided with support rods, the support rods on the first cross beam and the second cross beam are arranged alternately and connected with the drift tubes one by one; the first cross beam is connected with a positive electrode, and the second cross beam is connected with a negative electrode, for establishing a radio frequency electric field between adjacent drift tubes. In the present application, the drift tube is arranged as a square tube with open slots at both ends and mixed arrangement, so that the linear accelerator can not only keep a high acceleration gradient in the longitudinal direction, but also have a strong focusing force in the transverse direction.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ion accelerators, in particular to a drift tube type linear accelerator. BACKGROUND

[0002] The drift tube type linear accelerator (DTL) is a commonly used type of linear accelerator, and its core structure is to arrange hollow cylinders with specific lengths and inner and outer diameters at specific gap distances, and to establish a radio frequency electric field between adjacent two hollow cylinders for longitudinal acceleration and focusing of protons or heavy ions.

[0003] However, the electric field generated by this structure cannot simultaneously meet the requirements of the transverse and longitudinal transmission of the beam. In order to increase the transverse focusing force of the electric field, researchers have thought of many methods, such as sacrificing longitudinal acceleration and bunching performance to obtain transverse focusing force by changing the acceleration phase, or installing magnetic focusing elements in the cavity, but the above methods will cause the acceleration gradient of the accelerator to decrease, the power consumption to increase, and the cavity size to increase, thereby greatly increasing the stability of the accelerator and the production, operation and maintenance costs. SUMMARY

[0004] The present application aims to solve the technical problems existing in the related art. To this end, the present application provides a drift tube type linear accelerator, which optimizes the acceleration structure of the linear accelerator by adopting a half-open square drift tube combined arrangement form, so as to realize the purpose of ensuring that the accelerator has a high acceleration gradient and a strong transverse focusing force at the same time.

[0005] The present application provides a drift tube type linear accelerator, comprising:

[0006] A cavity cylinder is provided as a shell structure with an internal cavity;

[0007] A drift tube is provided as a square tube with open slots at both ends;

[0008] A first cross beam is installed at the upper part of the cavity;

[0009] A second cross beam is installed at the lower part of the cavity;

[0010] Wherein, a plurality of drift tubes are arranged at intervals along the central axis of the cavity cylinder, the first cross beam and the second cross beam are both provided with support rods, and the support rods on the first cross beam and the second cross beam are alternately arranged and connected one by one with the drift tubes;

[0011] The first cross beam is connected with a positive electrode, and the second cross beam is connected with a negative electrode, for establishing a radio frequency electric field between adjacent drift tubes;

[0012] The drift tube includes a first drift tube for transverse focusing of the beam.

[0013] One end of the first drift tube is provided with an opening on the horizontal side wall, and the other end of the first drift tube is provided with an opening on the vertical side wall, so that the two ends of the first drift tube form open grooves with different extension directions;

[0014] The drift tube further comprises a second drift tube for converging focus conversion, and the second drift tube is provided with openings at two ends of the horizontal side wall or two ends of the vertical side wall, so that the two ends of the second drift tube form open grooves with the same extension direction.

[0015] According to the drift tube linear accelerator provided by the application, the length of the drift tube gradually increases from one end of the cavity cylinder to the other end of the cavity cylinder.

[0016] According to the drift tube linear accelerator provided by the application, any two adjacent drift tubes have opposite ends with different open groove extension directions.

[0017] According to the drift tube linear accelerator provided by the application, the first drift tube is arranged in the cavity cylinder in two postures: one is that one end of the first drift tube with the open groove extending in the vertical direction faces the left end of the cavity cylinder, and the other is that one end of the first drift tube with the open groove extending in the horizontal direction faces the left end of the cavity cylinder.

[0018] According to the drift tube linear accelerator provided by the application, a plurality of first drift tubes are arranged in the same posture in series, for superimposing focusing strength in the set direction corresponding to the posture.

[0019] According to the drift tube linear accelerator provided by the application, the second drift tube is arranged between two first drift tubes with different postures to form a periodic FODO focusing structure.

[0020] According to the drift tube linear accelerator provided by the application, the first cross beam and the second cross beam both extend from the left end of the cavity cylinder to the right end of the cavity cylinder, and are symmetrically distributed relative to the central axis of the cavity cylinder.

[0021] According to the drift tube linear accelerator provided by the application, the two end faces of the cavity cylinder are respectively provided with beam holes for communicating the inside and outside of the cavity, and the central axis of the beam hole coincides with the central axis of the cavity cylinder.

[0022] The one or more technical solutions in the application have at least one of the following technical effects:

[0023] The drift tube is arranged as a square tube and open grooves are arranged at two ends of the square tube to form a semi-open square drift tube, and the linear accelerator is arranged in a mixed arrangement by opposing the drift tube, so that the linear accelerator can not only keep a high acceleration gradient in the longitudinal direction, but also has a strong focusing force in the transverse direction, thereby shortening the length of the linear accelerator and improving the extracted beam quality and transmission efficiency of the linear accelerator.

[0024] In addition to the technical problems solved by the application, the technical features of the technical solutions and the advantages brought by the technical features, other technical features of the application and the advantages brought by the technical features will be further described with reference to the drawings or understood through the practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the application or in the related art, the drawings needed to be used in the embodiments or the related art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0026] Figure 1 A perspective view of the drift tube type linear accelerator according to the embodiment of the application is provided.

[0027] Figure 2 A perspective view of the drift tube type linear accelerator according to the embodiment of the application is provided.

[0028] Figure 3 A longitudinal symmetry plane view of the drift tube type linear accelerator according to the embodiment of the application is provided.

[0029] Figure 4 A perspective view of the first drift tube according to the embodiment of the application is provided.

[0030] Figure 5 A perspective view of the second drift tube according to the embodiment of the application is provided.

[0031] Reference signs:

[0032] 10, cavity barrel; 11, beam hole; 20, first cross beam; 30, second cross beam; 40, support rod; 50, drift tube; 51, open groove; 50a, first drift tube; 50b, second drift tube. DETAILED DESCRIPTION

[0033] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be clearly described below with reference to the drawings in the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0034] In the embodiments of the present application, a drift tube type linear accelerator is introduced.

[0035] As shown in the drawings, Figures 1 to 3 The drift tube type linear accelerator mainly comprises a cavity cylinder 10, a drift tube 50, a first cross beam 20, a second cross beam 30 and a support rod 40.

[0036] The cavity cylinder 10 is arranged as a shell structure with a cavity inside. The cavity can be arranged as a cylindrical space or a cuboid space.

[0037] The drift tube 50 is arranged as a square tube with open grooves 51 at both ends. A plurality of the drift tubes 50 are arranged in the cavity in a spaced manner. The central axis of each drift tube 50 is arranged to coincide with the central axis of the cavity cylinder 10.

[0038] The first cross beam 20 is installed at the upper part of the cavity. The second cross beam 30 is installed at the lower part of the cavity.

[0039] Specifically, a plurality of the drift tubes 50 are arranged in the cavity in a spaced manner along the central axis of the cavity cylinder 10. The first cross beam 20 and the second cross beam 30 are both provided with a plurality of support rods 40. The support rods 40 on the first cross beam 20 and the second cross beam 30 are arranged alternately and connected one by one with the drift tubes 50.

[0040] Compared with the complex connection between the traditional cylindrical drift tube 50 and the support rod 40, the drift tube 50 in the present application adopts a square tube structure with more positioning planes, which is conducive to the connection and fixation with the support rod 40. A single drift tube 50 can be conveniently arranged in the cavity cylinder 10 by only one support rod 40, which can not only simplify the structure and reduce the transverse size of the cavity cylinder 10, but also facilitate collimation measurement and ensure more accurate results.

[0041] In addition, the first cross beam 20 and the second cross beam 30 are connected with positive electrodes and negative electrodes respectively. Specifically, the first cross beam 20 is connected with positive electrodes, the second cross beam 30 is connected with negative electrodes, or vice versa, so as to form a potential difference between two adjacent drift tubes 50, for establishing a radio frequency electric field between the adjacent drift tubes 50.

[0042] Further, the first beam 20 and the second beam 30 each extend from the left end of the cavity 10 to the right end of the cavity 10. Moreover, the first beam 20 and the second beam 30 are symmetrically arranged with respect to the central axis of the cavity 10.

[0043] For example, the first beam 20 extends downward from the top surface of the cavity, the second beam 30 extends upward from the bottom surface of the cavity, and the first beam 20 and the second beam 30 have a spacing therebetween. The drift tube 50 is suspended between the first beam 20 and the second beam 30 by the support rod 40.

[0044] The cavity 10 is provided with beam holes 11 at both ends of the cavity 10 for communicating the inside and outside of the cavity. The central axis of the beam hole 11 coincides with the central axis of the cavity 10.

[0045] Further, any two adjacent drift tubes 50 have opposite ends with different extension directions of the open slots 51.

[0046] The opposite ends of the adjacent drift tubes 50 have a potential difference and the extension directions of the open slots 51 are perpendicular to each other. The electric field formed by the potential difference has components in the beam direction and the transverse direction (i.e. the horizontal direction or the vertical direction). The linear accelerator uses the potential difference to accelerate protons or heavy ions, and the mutual perpendicularity of the open slots 51 can achieve the convergence of the beam in the transverse direction. The component of the potential difference in the transverse direction is related to the extension direction of the open slot 51.

[0047] Specifically, the drift tube 50 includes a first drift tube 50a for transverse focusing of the beam.

[0048] As shown in Figs. 1 and 2, the first drift tube 50a has an opening on the horizontal side wall at one end thereof, and an opening on the vertical side wall at the other end thereof, so that the two ends of the first drift tube 50a form open slots 51 with different extension directions. Figure 2 Figure 4 The open slots 51 at the two ends of the first drift tube 50a extend in the horizontal direction and the vertical direction, respectively, so as to separate the electric focusing forces in the horizontal and vertical directions, and to alternately converge and diverge the beam in the horizontal and vertical directions, which is beneficial to the transverse control of the beam.

[0049] Since the conventional linear accelerator uses a cylindrical drift tube 50, it is not possible to distinguish the electric focusing forces in the horizontal and vertical directions, and the beam is usually focused or diverged in the horizontal and vertical directions at the same time, which causes coupling of the transverse beam dynamics and is not conducive to envelope control and beam transmission.

[0050] ​The first drift tube 50a in the application can separate the electric focusing function in horizontal and vertical directions. That is, in a single accelerating unit, there is only focusing force in one direction and defocusing force in the other direction (horizontal focusing and vertical defocusing or horizontal defocusing and vertical focusing), which is similar to the function of a quadrupole magnet, weakens the coupling effect of the beam in two directions, helps to control the beam transverse envelope, and improves the beam quality and transmission efficiency.

[0051] Meanwhile, the drift tube 50 further comprises a second drift tube 50b for converging and diverging focus conversion.

[0052] As shown in Figure 2 and Figure 5 The second drift tube 50b is provided with an opening at both ends of the horizontal side wall or the vertical side wall, so that the two ends of the second drift tube 50b form an open slot 51 with the same extension direction.

[0053] In particular, the first drift tube 50a is arranged in the cavity 10 in two postures: one end of the first drift tube 50a with the open slot 51 extending in the vertical direction faces the left end of the cavity 10, and the other end of the first drift tube 50a with the open slot 51 extending in the horizontal direction faces the left end of the cavity 10.

[0054] Correspondingly, the second drift tube 50b is also arranged in the cavity 10 in two postures: the second drift tube 50b is arranged with the open slot 51 extending in the vertical direction, and the second drift tube 50b is arranged with the open slot 51 extending in the horizontal direction. Thus, four types of drift tubes 50 can be arranged in the cavity 10, two for converging and diverging focus in horizontal and vertical directions, and two for converging and diverging focus conversion.

[0055] A plurality of first drift tubes 50a are arranged in the same posture to superimpose the focusing strength in the set direction corresponding to the posture. Each first drift tube 50a has a focusing strength, and the continuous arrangement can superimpose the focusing strength in a specific direction. Meanwhile, by adjusting the number of continuous arrangements of the first drift tube 50a in the same posture, the cumulative electric focusing strength can be flexibly adjusted, and the parameter selection range in the beam dynamics design is expanded.

[0056] According to the type and energy of the ion beam, the number of continuous arrangements of the first drift tube 50a in the same posture can be optimized to obtain a reasonable periodic focusing structure, thereby optimizing the transverse envelope of the beam and obtaining a high-quality and high-transmission-efficiency ion beam.

[0057] Further, the second drift tube 50b is arranged between two first drift tubes 50a in different postures to form a periodic FODO focusing structure.

[0058] The periodic FODO focusing structure similar to the strong focusing principle of the accelerator can be obtained by setting a second drift tube 50b between the first drift tubes 50a in two different postures to realize a specific beam dynamics design scheme.

[0059] Specifically, the periodic FODO focusing structure refers to an important repeating unit in the design of a particle accelerator, which maintains the stable transmission of a particle beam through a series of components arranged in a specific order. The basic FODO unit is composed of a focusing magnet (F), a drift space (O), a defocusing magnet (D) and another drift space (O). In the periodic FODO structure, these basic units are repeatedly arranged along the beam path to form a chain of FODO units.

[0060] In the embodiment, the drift tube 50 is set as a square tube, and the open slots 51 are arranged at both ends to form a semi-open square drift tube 50. By mixing the square drift tubes 50, the linear accelerator can not only maintain a high acceleration gradient in the longitudinal direction, but also have strong focusing force in the transverse direction, thereby shortening the length of the linear accelerator and improving the extracted beam quality and transmission efficiency of the linear accelerator.

[0061] Based on the above embodiment, another embodiment of the present application introduces a drift tube type linear accelerator. Inside the cavity, the length of the drift tube 50 gradually increases from one end of the cavity 10 to the other end of the cavity 10.

[0062] As shown in Figure 3 , several drift tubes 50 are arranged in the cavity in the form of gradually increasing their own length from one end of the cavity 10 to the other end of the cavity 10.

[0063] Compared with the traditional cylindrical drift tube 50, if the size of the through hole for passing the beam in the drift tube 50 in the present application is the same as that of the through hole for passing the beam in the cylindrical drift tube 50, the transverse cross section of the drift tube 50 in the present application will be significantly larger than that of the cylindrical drift tube 50, so that the drift tube type linear accelerator with square tube structure has larger beam transverse acceptance, which is beneficial to improve the output current of the entire accelerator system.

[0064] In summary, the drift tube linear accelerator in the application sets the drift tube 50 as a square tube structure and arranges it in a mixed manner, forming a brand-new acceleration structure. The acceleration structure can make the drift tube linear accelerator involving protons and heavy ions have a high acceleration gradient and a stronger lateral focusing force, can freely adjust the converging and diverging effects and their intensity, is beneficial to the beam envelope control and dynamic design, and further improves the extracted beam quality and transmission efficiency of the linear accelerator. Meanwhile, the structure has a larger beam acceptance, a simpler collimation installation method, and lower production processing and operation and maintenance costs.

[0065] Meanwhile, the drift tube linear accelerator in the application will have a profound impact on the fields of proton and heavy ion tumor cancer treatment, material irradiation, radioisotope production, aerospace research and the like, and will bring huge economic benefits.

[0066] In the description of the embodiments of the application, it should be noted that the orientations or positional relationships indicated by the terms “center”, “longitudinal”, “lateral”, “upper”, “lower”, “front”, “rear”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inner”, “outer” and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the embodiments of the application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the embodiments of the application. In addition, the terms “first”, “second”, “third” are only for the purpose of description and cannot be understood as indicating or implying relative importance.

[0067] In the description of the embodiments of the application, it should be noted that, unless otherwise explicitly specified and limited, the terms “connected” and “connected” should be understood in a broad sense, for example, can be fixedly connected, can be detachably connected, or integrally connected; can be mechanically connected, or electrically connected; can be directly connected, or indirectly connected through an intermediate medium. For those skilled in the art, the specific meanings of the above terms in the embodiments of the application can be understood according to the specific circumstances.

[0068] In the embodiments of the application, unless otherwise explicitly specified and limited, the first feature is “on” or “under” the second feature, which can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature can be directly above or obliquely above the second feature, or only means that the horizontal height of the first feature is higher than that of the second feature. The first feature can be directly below or obliquely below the second feature, or only means that the horizontal height of the first feature is less than that of the second feature.

[0069] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In the present specification, the illustrative description of the above terms is not limited to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, different embodiments or examples described in the present specification and the features of different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0070] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A drift tube type linear accelerator characterized by, The utility model relates to a cavity tube (10) is provided with the cavity in the inside, the drift tube (50) is provided with the open slot (51) in both ends, the first crossbeam (20) is installed in the upper portion of the cavity, the second crossbeam (30) is installed in the lower portion of the cavity, wherein a plurality of the drift tube (50) is arranged along the central axis of the cavity tube (10) in the cavity, the first crossbeam (20) and the second crossbeam (30) are provided with the support (40), the support (40) on the first crossbeam (20) and the second crossbeam (30) are arranged alternately and are connected with the drift tube (50) one by one, the first crossbeam (20) is connected with the positive electrode, the second crossbeam (30) is connected with the negative electrode, and the radio frequency electric field is established between adjacent the drift tube (50), the drift tube (50) includes the first drift tube (50a) for the lateral focusing of beam current, one end of the first drift tube (50a) is provided with the aperture on the horizontal side wall, the other end of the first drift tube (50a) is provided with the aperture on the vertical side wall, the two ends of the first drift tube (50a) form the open slot (51) with different extension directions, the first drift tube (50a) is provided in the cavity tube (10) in two postures: one is that the one end of the first drift tube (50a) with the open slot (51) extending in the vertical direction faces the left end of the cavity tube (10), and the other is that the one end of the first drift tube (50a) with the open slot (51) extending in the horizontal direction faces the left end of the cavity tube (10), the drift tube (50) further includes the second drift tube (50b) for converging focus conversion, the second drift tube (50b) is provided with the aperture in both ends of the horizontal side wall or both ends of the vertical side wall, and the two ends of the second drift tube (50b) form the open slot (51) with the same extension direction, the second drift tube (50b) is arranged between the two first drift tubes (50a) with different postures to form the periodic FODO focusing structure, the length of the drift tube (50) gradually increases from one end of the cavity tube (10) to the other end of the cavity tube (10), any adjacent two drift tubes (50) have different end portions as opposite ends, a plurality of the first drift tubes (50a) are arranged continuously in the same posture, and the focusing intensity is superimposed in the set direction corresponding to the posture, the first crossbeam (20) and the second crossbeam (30) extend from the left end of the cavity tube (10) to the right end of the cavity tube (10) and are symmetrically distributed relative to the central axis of the cavity tube (10), the two end faces of the cavity tube (10) are respectively provided with the beam hole (11) for communicating inside and outside the cavity, and the central axis of the beam hole (11) coincides with the central axis of the cavity tube (10). ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2. The drift tube linear accelerator of claim 1, wherein, ​ 3. The drift tube linear accelerator of claim 2, wherein, ​ 4. The drift tube linear accelerator of claim 3, wherein, ​ 5. The drift tube linear accelerator of claim 4, wherein, ​ 6. The drift tube linear accelerator of claim 5, wherein, ​

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