Drift tube linac and charged particle linac system

Abstract

Disclosed in the present invention are a drift tube linac and a charged particle linac system. The drift tube linac comprises an accelerator housing; a beam inlet and a beam outlet are respectively formed in end plates on two sides of the accelerator housing; supporting plates are respectively provided at the top and bottom inside the accelerator housing; a plurality of drift tubes are arranged at intervals in the axial direction between the end plates on the two sides in the accelerator housing; adjacent drift tubes are alternately fixed to the upper and lower supporting plates by means of supporting rods; hollow end drift tubes are provided on the inner sides of the end plates on the two sides; an isolation tube is connected between every two adjacent drift tubes in a vacuum sealing manner; the internal spaces of the drift tubes and the internal spaces of the isolation tubes form an acceleration area through which beams pass at an accelerated rate; the remaining space in the accelerator housing is a non-acceleration area; the acceleration area is communicated with a vacuum pump; the acceleration area is maintained in high vacuum by the vacuum pump; and the non-acceleration area is in an atmospheric pressure or dry gas atmosphere. In the present invention, the non-acceleration area works under the atmospheric pressure condition, so that the accelerator housing does not need to consider vacuum sealing requirements, thereby achieving a light weight and a simple structure.

Description

Drift tube linear accelerator and charged particle linear accelerator system Technical Field

[0001] The present invention relates to particle acceleration technology and its applications, specifically to a drift tube linear accelerator and charged particle linear accelerator system for accelerating protons, helium particles, or heavy ions. These linear accelerators can be used as linear injection accelerators in proton or heavy ion tumor treatment devices or as devices for producing radionuclides. Background Art

[0002] Proton or heavy ion devices typically used for cancer treatment require a particle accelerator to accelerate charged particles to approximately 20% to 70% of the speed of light. These accelerators typically combine a linear injection accelerator (LIA) and a synchrotron accelerator. The LIA typically consists of an ion source (such as an ECR ion source) to generate the charged particles, a radio frequency quadrupole linear accelerator (RFQ) accelerator, and a drift tube accelerator connected to the RFQ. Charged particles accelerated to the injection energy by the drift tube accelerator are then transported via a medium-energy transport line to the injection port of the synchrotron accelerator. The injected charged particles are ultimately accelerated by the synchrotron accelerator to the energy required for cancer treatment. Another type of accelerator used for radionuclide production directly utilizes the charged particles output by the drift tube accelerator for target production. A drift tube accelerator is a commonly used charged particle accelerator. It consists of two or more hollow cylindrical drift tube electrodes arranged within an accelerating resonant cavity along the beam's travel direction. High-frequency power is supplied to the accelerating resonant cavity, specifically by feeding high-power microwaves at the resonant frequency into the accelerating resonant cavity. This generates a high-frequency electric field between the drift tube electrodes, accelerating charged particles (e.g., protons or carbon ions) along the beam's travel direction as they pass through the gaps between adjacent drift tubes. As described in patent document (Announcement CN103026802B), a type of drift tube linac, called an APF-IH linac, accelerates charged particles while simultaneously accelerating them. The alternating electric field formed between the drift tubes effectively transports the particles, preventing them from diverging excessively and being lost during the acceleration process. To achieve the same goal, some drift tube linacs also incorporate focusing quadrupole magnets positioned within the accelerating cavity to prevent excessive beam divergence. In both cases, the basic principle of acceleration of charged particles by the drift tube linear accelerator is the same.

[0003] During operation, a drift tube linear accelerator (LINAC) requires maintaining a high vacuum within the accelerator chamber to prevent discharges and loss of the charged particle beam due to collisions with gas molecules. Existing drift tube LINACs, such as the alternating phase focusing (APF) drift tube accelerators disclosed in Chinese utility model patents CN216982176U and CN103026802B, comprise a first housing, a second housing, and an accelerating body. The first housing defines a first accelerating half-cavity through its inner circumferential wall, while the second housing defines a second accelerating half-cavity through its inner circumferential wall. The accelerating body is a central abacus structure integrally formed with a plate-like structure. The accelerating body includes a frame, drift tubes, and accelerating gaps arranged alternately along an axis within the frame. The accelerating body is mounted and fixed between the first and second housings via the frame, such that the first and second accelerating half-cavities are located on opposite sides of the accelerator body. The first, second, and accelerating half-cavities, combined with the accelerating gap, form the accelerating chamber of the APF drift tube accelerator. The entire interior of the accelerator is the accelerating cavity. This large volume requires work to be performed on the entire cavity during evacuation, resulting in long evacuation times and low efficiency. Maintaining a high vacuum level throughout the cavity also requires a vacuum pump with a large exhaust capacity. Furthermore, the power coupler, which provides high-power microwaves to the accelerating cavity, the cavity microwave signal pickup required for accelerator control, and the tuner, which stabilizes the resonant frequency and electric field distribution within the cavity, all require both vacuum-sealed and high-frequency-sealed structures. This structure is the primary reason for the complex manufacturing process, high cost, and susceptibility to failure of the coupler and other components. In particular, the tuner must adjust its insertion depth within the accelerating cavity while maintaining both a vacuum and high-frequency seal. Furthermore, because the entire accelerating cavity must operate under high vacuum conditions, the accelerator cavity must withstand tens or even hundreds of tons of atmospheric pressure, calculated at 1 kg per square centimeter. This inevitably results in a wall thickness of several centimeters or more, significantly increasing the weight of the accelerator and material costs. For example, Chinese invention patent application CN113784495A discloses a high-gradient, high-intensity harmonic accelerator, and Chinese invention patent CN104703380B discloses a single-cavity, multi-beam drift tube ion accelerator. Both of these devices directly install drift tubes at intervals within the accelerator cavity, and the entire internal space of the cavity is connected. Both devices suffer from the aforementioned problems of long vacuum pumping time, low efficiency, high energy consumption, and complex structure. At the same time, components such as the high-frequency power coupler, the tuner for adjusting the resonant frequency and electric field distribution, and the signal pickup installed on the accelerator need to have both vacuum sealing and high-frequency sealing structures to maintain the high vacuum state within the accelerator cavity and prevent the electromagnetic field within the cavity from leaking outside the acceleration cavity. In particular, the vacuum sealing structure of the high-frequency power coupler is particularly complex, requiring advanced ceramic-metal welding technology and a variable diameter structure to maintain impedance matching during manufacturing.At the same time, in order to maintain the vacuum inside the accelerator cavity, the accelerator shell usually requires a metal shell several centimeters thick to offset the pressure generated by the pressure difference between the inside and outside, which makes the accelerator cavity bulky and increases the manufacturing cost. Summary of the Invention

[0004] In order to solve the above-mentioned problems of existing drift tube linear accelerators, the present invention provides a new drift tube linear accelerator and charged particle linear accelerator system, which only needs to maintain a high vacuum in a limited range of space with an accelerating electric field in the accelerator cavity where the beam passes, while the rest of the accelerator cavity can operate at atmospheric pressure. The system has the advantages of simple structure, light weight, reliability, simple maintenance and low manufacturing cost.

[0005] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0006] A drift tube linear accelerator comprises a hollow accelerator shell, wherein end plates on both sides of the accelerator shell are respectively provided with a beam inlet and a beam outlet, support plates are respectively provided at the upper and lower parts of the accelerator shell, a plurality of drift tubes are axially spaced apart between the end plates on both sides of the accelerator shell, adjacent drift tubes are alternately fixed to the upper and lower support plates by support rods, hollow end drift tubes for beam passage are provided on the inner sides of the end plates on both sides, isolation tubes are vacuum-sealed and connected between all adjacent drift tubes, the isolation tubes are made of insulating and high-frequency electromagnetic wave transparent materials, from the beam inlet, the inlet end drift tube, the isolation tube, the drift tube, the isolation tube to the outlet end drift tube and the beam outlet, the internal space of the drift tube and the isolation tube forms an acceleration zone through which the beam is accelerated, a non-acceleration zone is formed between the outside of the drift tube and the isolation tube and the inner wall of the accelerator shell, a vacuum pump is provided outside the beam inlet or the beam outlet, the vacuum pump is connected to the acceleration zone, the acceleration zone is maintained at high vacuum by the vacuum pump, and the non-acceleration zone is in atmospheric pressure or dry gas atmosphere.

[0007] Preferably, the vacuum degree of the acceleration zone is higher than 10 -3 Pa.

[0008] Preferably, the non-acceleration zone is filled with an inert gas.

[0009] Preferably, the isolation tube is made of ceramic.

[0010] In another preferred embodiment, the isolation tube is made of aluminum oxide or aluminum dioxide.

[0011] Preferably, the isolation tube and the drift tube are sealed and connected via an O-ring.

[0012] Furthermore, it also includes at least one high-frequency power coupler. The accelerator shell is provided with a through coupler connection port. The high-frequency power coupler is high-frequency sealed and installed at the coupler connection port, communicating with the non-acceleration area.

[0013] Furthermore, the high-frequency power coupler includes a power coupler outer conductor, a power coupler inner conductor and a power coupler coupler ring. The power coupler inner conductor is coaxially installed in the inner cavity of the power coupler outer conductor. The power coupler coupler ring is connected to the power coupler inner conductor. The inner diameter of the power coupler outer conductor and the outer diameter of the power coupler inner conductor form a coaxial structure with uniform impedance from the inlet end to the outlet end. The inner surface of the power coupler inner conductor and the outer surface of the power coupler outer conductor are tightly connected.

[0014] Furthermore, the accelerator housing is provided with a plurality of signal pickup ports and tuner installation ports.

[0015] A charged particle linear accelerator system including the above-mentioned drift tube linear accelerator also includes an ion source and an RFQ linear accelerator. The ion source and the RFQ linear accelerator are connected via a low-energy transport line pipeline. The rear end of the RFQ linear accelerator is connected to the drift tube linear accelerator via a vacuum beam pipeline. The RFQ linear accelerator is connected to a radio frequency power source A, and the drift tube linear accelerator is connected to a radio frequency power source B.

[0016] The beneficial effects of the present invention are:

[0017] In the present invention, an isolation tube made of an insulating material that is easily permeable to high-frequency microwaves is added between each pair of adjacent drift tubes in the cavity of the drift tube linear accelerator. The isolation tube is also hollow in structure, and a charged particle beam can exit the drift tube, enter the isolation tube, and then enter the next drift tube. The isolation tube and the drift tube are closely connected to form a vacuum seal, forming an independent acceleration zone space inside the drift tube pipeline and the isolation tube pipeline. The acceleration zone space is connected to the beam inlet and beam outlet of the acceleration cavity. In this way, the drift tube and the space between the outside of the isolation tube and the inner wall of the acceleration cavity form a non-acceleration zone. When the accelerator is working, it is only necessary to use a vacuum pump to evacuate the acceleration area from the beam inlet or beam outlet end of the acceleration cavity and maintain a high vacuum degree to ensure that the charged particles in the acceleration area are accelerated smoothly; the non-acceleration area can work under non-high vacuum conditions such as atmospheric pressure conditions, so the accelerator shell does not need to consider the mechanical deformation caused by the pressure difference, eliminating the vacuum sealing requirements and vacuum exhaust requirements, which can greatly reduce the accelerator shell wall thickness and simplify the accelerator shell manufacturing process, achieving lightweight and simplified structure; the high-frequency power coupler and the operating frequency and electric field distribution tuner that must be installed on the accelerator shell no longer need to consider vacuum sealing, and only need to meet high-frequency sealing requirements, thereby greatly simplifying the structure and processing costs, as well as the manufacturing cycle, and also facilitating the maintenance and repair of the accelerator, solving the problems faced by linear accelerators with existing technologies, and can provide a drift tube linear accelerator with light weight, simple structure, reliable performance, easy maintenance, easy manufacturing and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0019] FIG1 is a cross-sectional view of a drift tube linear accelerator according to the present invention;

[0020] FIG2 is a schematic diagram of a three-dimensional structure of a central cross section of a drift tube linear accelerator according to the present invention;

[0021] FIG3 is a second schematic diagram of the central cross-sectional three-dimensional structure of the drift tube linear accelerator of the present invention;

[0022] FIG4 is a schematic diagram of a three-dimensional structure of a central cross section of a drift tube and an isolation tube in the present invention;

[0023] FIG5 is a cross-sectional schematic diagram of a high frequency power coupler of the present invention;

[0024] FIG6 is a schematic diagram of the structure of a charged particle linear accelerator system according to the present invention;

[0025] FIG7 is a schematic diagram of the electric field distribution in the drift tube gap.

[0026] The accompanying drawings are described as follows: 0-drift tube linear accelerator 1-accelerator housing 2-support plate 3-drift tube 4-support rod 5-isolation tube 6-acceleration area 7-non-acceleration area 8-high-frequency power coupler 11-beam inlet 12-beam outlet 13-coupler connection port 14-signal pickup port 15-vacuum pump 81-power coupler outer conductor 82-power coupler inner conductor 83-power coupler coupler ring 100-linear acceleration system 101-ion source 102-low energy transport line pipeline 103-RFQ linear accelerator 104-RF power source A 105-RF power source B 106-beam monitor 107-other accelerators or beam application ends DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application for protection, but merely represents the selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0028] Example 1

[0029] The present embodiment discloses a drift tube linear accelerator 0, as shown in Figures 1 to 5, comprising a hollow accelerator housing 1, with beam inlets 11 and beam outlets 12 respectively provided on the end plates on both sides of the accelerator housing 1, support plates 2 respectively provided on the upper and lower sides of the accelerator housing 1, a plurality of drift tubes 3 are axially spaced between the end plates on both sides of the accelerator housing 1, adjacent drift tubes 3 are alternately fixed on the upper and lower support plates 2 by support rods 4, hollow end drift tubes for beam passage are provided on the inner sides of the end plates on both sides, and the end drift tubes are connected to the drift tube 3 and the adjacent drift tubes by an isolation tube 5, and the isolation tube 5 adopts an insulating, high-frequency electric The accelerator is made of a material that is transparent to magnetic waves, and the connection between the isolation tube 5 and the drift tube 3 is a vacuum-tight connection. From the beam inlet 11, the beam passes through the drift tube at the inlet end, the isolation tube, the drift tube, the isolation tube, and the beam outlet 12 at the outlet end plate in sequence. The internal space of the drift tube 3 and the isolation tube 5 forms an acceleration zone 6 through which the beam is accelerated. A non-acceleration zone 7 is formed between the outside of the drift tube 3 and the isolation tube 5 and the inner wall of the accelerator housing 1. A vacuum pump 15 is provided outside the beam inlet 11 or the beam outlet 12. The vacuum pump 15 is connected to the acceleration zone 6. The acceleration zone 6 is maintained at a high vacuum by the vacuum pump 15 to provide normal acceleration of the charged particle beam. The non-acceleration zone 7 is in an atmospheric pressure or dry gas atmosphere.

[0030] During operation, the vacuum pump 15 evacuates the acceleration zone 6. The vacuum degree of the acceleration zone 6 is higher than that of the non-acceleration zone 7. Preferably, the vacuum degree of the acceleration zone 6 is higher than 10 -3 Pa, the air pressure of the non-acceleration zone 7 is atmospheric pressure or dry gas atmosphere. Preferably, the non-acceleration zone 7 is filled with an inert gas.

[0031] Preferably, the isolation tube 5 is made of ceramic, alumina or aluminum oxide.

[0032] Furthermore, it also includes at least one high-frequency power coupler 8. The accelerator housing 1 is provided with a through coupler connection port 13. The high-frequency power coupler 8 is high-frequency sealed and installed at the coupler connection port 13, communicating with the non-acceleration zone 7. The high-frequency power coupler 8 is made of metal material and includes a power coupler outer conductor 81, a power coupler inner conductor 82, and a power coupler coupler ring 83. The power coupler inner conductor 82 is coaxially installed in the inner cavity of the power coupler outer conductor 81. The power coupler coupler ring 83 connects the power coupler inner conductor 82. The inner diameter of the power coupler outer conductor 81 and the outer diameter of the power coupler inner conductor 82 form a coaxial structure with uniform impedance from the inlet end to the outlet end. The inner surface of the power coupler inner conductor 82 and the outer surface of the power coupler outer conductor 81 are tightly connected. At the same time, the high-frequency power coupler 8 in the present invention does not have a vacuum-sealed ceramic component, that is, no vacuum-sealed structure is required between the power coupler inner conductor 82 and the power coupler outer conductor 81.

[0033] The accelerator housing 1 is also provided with a plurality of signal pickup ports 14 and a tuner installation port.

[0034] Example 2

[0035] This embodiment discloses a charged particle linear accelerator system 100, as shown in Figure 6. In addition to the aforementioned drift tube linear accelerator 0, it also includes an ion source 101 and an RFQ linear accelerator 103. Ion source 101 is a charged particle generator. Ion source 101 and RFQ linear accelerator 103 are connected via a low-energy transport line 102. The rear end of RFQ linear accelerator 103 is connected to drift tube linear accelerator 0 via a vacuum beam line. RFQ linear accelerator 103 is connected to RF power source A 104, while drift tube linear accelerator 0 is connected to RF power source B 105. In operation, the rear end of this embodiment's linear accelerator system 100 is connected to a beam monitor 106, which is then connected to other accelerators or a beam application terminal 107.

[0036] The use process of the present invention is:

[0037] During use, as shown in FIG6 , the charged particle generator ion source 101 of the linear accelerator system, the low-energy transport line pipeline 102 between the ion source 101 and the RFQ linear accelerator 103, the RFQ linear accelerator 103, and the drift tube linear accelerator 0 are connected by a vacuum beam pipeline. A vacuum pump is used to evacuate the vacuum beam pipeline of the entire system, the cavity of the RFQ linear accelerator 103, and the acceleration zone of the drift tube linear accelerator 0, and maintain the vacuum level within the operating range of the linear accelerator system. A coaxial microwave feeder connects the high-frequency power source B105 to the drift tube linear accelerator's power coupler 8. The coaxial microwave inner conductor and the power coupler's inner conductor are directly connected, all the way to the power coupler's coupling ring, operating at the same pressure (atmospheric pressure). The tuner mounted on the accelerator housing 1 only requires high-frequency sealing, not vacuum sealing. Therefore, its insertion depth within the accelerating cavity can be easily adjusted to adjust or stabilize the accelerator's resonant frequency. Heat generated by the accelerator cavity itself can also be easily dissipated via cooling water pipes laid within the accelerator housing, maintaining the accelerator's resonant frequency at a stable operating frequency. Because only the acceleration zone 6 is in a high vacuum state, the accelerator housing 2 is not deformed by vacuum extraction. It can be made of thinner oxygen-free copper (OFCu), using less material, resulting in lower cost and lighter weight.

[0038] Then, the various control systems and power supply systems are activated. The electric field distribution in the drift tube gap is shown in Figure 7. The charged particle beam accelerated by the RFQ linear accelerator enters the beam inlet of the drift tube linear accelerator. Passing through the acceleration gaps between drift tubes within the acceleration zone, the charged particles are accelerated by the high-frequency electric field between the drift tubes. Finally, the charged particles enter the beam exit pipe, completing their acceleration. It is important to note that the inner diameter of the isolation tubes between adjacent drift tubes can be larger than the outer diameter of the drift tubes. The vacuum seal interface between the isolation tubes and the drift tubes can also be positioned radially outward from the drift tubes, as close as possible to the drift tube support rods. This ensures that the walls of the isolation tubes are essentially located in a spatial location unaffected by the accelerating electric field between the drift tubes. Because the electric field distribution within the drift tube accelerator cavity is concentrated near the gaps between each pair of adjacent drift tubes, while the high-frequency magnetic field is concentrated elsewhere, this arrangement ensures that the isolation tubes are located where the electric field is negligible or negligible, preventing sparking. Because the isolation tube is constructed of a ceramic material with excellent high-frequency electromagnetic wave transmission properties, such as aluminum oxide ceramic, which has a dielectric constant (ε) as high as 9, high-frequency electromagnetic waves can easily penetrate the isolation tube wall and enter the acceleration zone, forming the high-frequency electric field between the drift tubes necessary to accelerate charged particles. The vacuum seal between the isolation tube and the drift tube can be achieved using sealing structures such as O-rings, adhesive bonding, or silver strip welding, all of which achieve the same desired effects and achieve the desired effects of the present invention.

[0039] In the present invention, an isolation tube made of an insulating material that is easily permeable to high-frequency microwaves is added between each pair of adjacent drift tubes in the cavity of the drift tube linear accelerator. The isolation tube is also hollow in structure, and a charged particle beam can exit the drift tube, enter the isolation tube, and then enter the next drift tube. The isolation tube and the drift tube are closely connected to form a vacuum seal, forming an independent acceleration zone space inside the drift tube pipeline and the isolation tube pipeline. The acceleration zone space is connected to the beam inlet and beam outlet of the acceleration cavity. In this way, the drift tube and the space between the outside of the isolation tube and the inner wall of the acceleration cavity form a non-acceleration zone. When the accelerator is working, it is only necessary to use a vacuum pump to evacuate the acceleration area from the beam inlet end or the beam outlet end of the acceleration cavity, and maintain a high vacuum degree to ensure that the charged particles in the acceleration area are smoothly accelerated; the non-acceleration area can operate under non-high vacuum conditions such as atmospheric pressure conditions, so the accelerator shell does not need to consider the mechanical deformation caused by the pressure difference, eliminating the vacuum sealing requirements and vacuum exhaust requirements, which can greatly reduce the wall thickness of the accelerator shell and simplify the accelerator shell manufacturing process, achieving lightweight and simplified structure; the vacuum exhaust pump system can be simplified, reducing the time for gas cleaning and vacuuming before the accelerator is used, and reducing energy consumption; the high-frequency power coupler and the operating frequency and electric field distribution tuner that must be installed on the accelerator shell no longer need to consider vacuum sealing, and only high-frequency sealing is required, thereby greatly simplifying the structure and processing cost, as well as the manufacturing cycle, and also facilitating the maintenance and repair of the accelerator, solving the problems faced by linear accelerators with existing technologies, and providing a drift tube linear accelerator with light weight, simple structure, reliable performance, easy maintenance, easy manufacturing and low cost.

[0040] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A drift tube linear accelerator, characterized in that: It includes a hollow accelerator housing (1). Beam inlets (11) and beam outlets (12) are respectively provided on the two end plates of the accelerator housing (1). Support plates (2) are respectively provided above and below inside the accelerator housing (1). A plurality of drift tubes (3) are axially spaced between the two end plates inside the accelerator housing (1). Adjacent drift tubes (3) are alternately fixed on the upper and lower support plates (2) through support rods (4). End drift tubes for beam passage are provided inside the two end plates on both sides and are hollow. All adjacent drift tubes (3) are vacuum-sealed and connected with isolation tubes (5). The isolation tubes (5) are made of insulating and high-frequency electromagnetic wave-transmitting materials. From the beam inlet, the inlet end drift tube, the isolation tube, the drift tube, the isolation tube to the outlet end drift tube and the beam outlet, an acceleration region (6) for the beam to accelerate through is formed in the internal spaces of the drift tubes (3) and the isolation tubes (5). A non-acceleration region (7) is formed between the outside of the drift tubes (3) and the isolation tubes (5) and the inner wall of the accelerator housing (1). A vacuum pump (15) is provided outside the beam inlet (11) or the beam outlet (12). The vacuum pump (15) is connected to the acceleration region (6). The acceleration region (6) is maintained at a high vacuum by the vacuum pump (15). The non-acceleration region (7) is in an atmospheric pressure or dry gas atmosphere.

2. The drift tube linear accelerator according to claim 1, wherein: The vacuum degree of the acceleration region (6) is higher than 10 -3 Pa.

3. The drift tube linear accelerator according to claim 1, characterized in that: An inert gas is filled in the non-acceleration region (7).

4. The drift tube linear accelerator according to claim 1, wherein: The isolation tube (5) is made of ceramic.

5. The drift tube linear accelerator according to claim 1, wherein: The isolation tube (5) is made of aluminum trioxide or alumina.

6. The drift tube linear accelerator according to claim 1, wherein: The isolation tube (5) is sealed and connected to the drift tube (3) through an O-ring seal.

7. The drift tube linear accelerator according to claim 1, characterized in that: It further includes at least one high-frequency power coupler (8). A through coupler connection port (13) is provided on the accelerator housing (1). The high-frequency power coupler (8) is installed at the coupler connection port (13) in a high-frequency sealed manner and is connected to the non-acceleration region (7).

8. The drift tube linear accelerator according to claim 7, wherein: The high-frequency power coupler (8) includes a power coupler outer conductor (81), a power coupler inner conductor (82) and a power coupler coupler ring (83). The power coupler inner conductor (82) is coaxially installed in the inner cavity of the power coupler outer conductor (81). The power coupler coupler ring (83) is connected to the power coupler inner conductor (82). The inner diameter of the power coupler outer conductor (81) and the outer diameter of the power coupler inner conductor (82) are of a coaxial structure with uniform impedance from the inlet end to the outlet end. The inner surface of the power coupler inner conductor (82) and the outer surface of the power coupler outer conductor (81) are tightly connected.

9. The drift tube linear accelerator according to claim 7, characterized in that: A plurality of signal pick-up ports (14) and tuner installation ports are further provided on the accelerator housing (1).

10. A charged particle linear accelerator system comprising the drift tube linear accelerator according to any one of claims 1-9, characterized in that: It further includes an ion source (101) and an RFQ linear accelerator (103). The ion source (101) is connected to the RFQ linear accelerator (103) through a low-energy transport line pipe (102). The rear end of the RFQ linear accelerator (103) is connected to a drift tube linear accelerator through a vacuum beam pipe. The RFQ linear accelerator (103) is connected to a radio frequency power source A (104), and the drift tube linear accelerator is connected to a radio frequency power source B (105).

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