A positive charge particle acceleration and focusing device

Abstract

The application discloses a positive charge particle acceleration and focusing device, and relates to the technical field of particle accelerators, which comprises an ion source device, an ion source mounting base plate and an electrode assembly, wherein the electrode assembly comprises a first cylinder electrode, a second cylinder electrode and a third cylinder electrode which are coaxially arranged in sequence; a gap is formed between the ion source mounting base plate and the first end of the first cylinder electrode, thereby forming a first electric field; a gap is formed between the second end of the first cylinder electrode and the first end of the second cylinder electrode in the axial direction, thereby forming a second electric field; a gap is formed between the second end of the second cylinder electrode and the first end of the third cylinder electrode in the axial direction, thereby forming a third electric field; the electric potential of the ion source mounting base plate is higher than that of the first cylinder electrode, and the electric potential of the second cylinder electrode is higher than that of the first cylinder electrode and the third cylinder electrode; the application greatly improves the transmission efficiency of positive charges, can rapidly increase the particle energy to more than 30keV, and has a compact structure and occupies a small space.

Description

Technical Field

[0001] This invention relates to the field of particle accelerator technology, and more specifically to a positively charged particle acceleration and focusing device. Background Technology

[0002] A particle accelerator is a device that uses electromagnetic fields to accelerate charged particles to high energies. It is not only widely used in cutting-edge scientific research such as the basic structure of matter and nuclear data measurement, but also has extremely high application value and broad market demand in many fields related to national economy and people's livelihood, such as particle medicine, material irradiation processing, clean energy, and particle imaging.

[0003] Particle acceleration requires an ultra-high vacuum environment. Some positively charged particles have low initial energy. For example, positive ions generated by ionization using a high-frequency ion source typically have an energy of less than 5 keV and a certain emission angle. The low particle energy, coupled with the fact that the beam outlet is close to the ion source inlet and the vacuum level is low, makes positively charged particles susceptible to the space charge effect during acceleration, which exacerbates divergence. Particles scattered on the vacuum wall will cause beam loss, resulting in low transmission efficiency.

[0004] To overcome the shortcomings in transmission efficiency, existing particle accelerators, such as proton therapy accelerators, can rapidly accelerate positively charged particles to higher energies using a radio frequency quadrupole field in a straight line, reducing the relative influence of space charge. Furthermore, they utilize periodic permanent magnet focusing (PPM) to minimize transmission losses, thereby improving particle transmission efficiency in the vacuum tube. However, these devices are bulky, typically occupying hundreds of square meters, and are expensive, have limited application conditions, complex structures, and high maintenance costs. In addition, the ion source itself has a limited lifespan and frequently requires disassembly and maintenance. Disassembly and maintenance of the ion source can easily affect the vacuum environment within subsequent particle accelerators, thus impacting transmission efficiency. Summary of the Invention

[0005] In view of one or more shortcomings of the prior art, the present invention provides a positively charged particle acceleration and focusing device with a compact transmission structure and small space occupation, which can realize the rapid acceleration and focusing of positively charged particles; at the same time, it isolates the vacuum, which greatly improves the transmission efficiency.

[0006] To achieve the above objectives, the present invention adopts one or more of the following technical solutions:

[0007] A positively charged particle acceleration and focusing device includes an ion source device, an ion source mounting chassis, and an electrode assembly. The ion source mounting chassis is connected to the ion source device, and there is a gap between the electrode assembly and the ion source mounting chassis. The ion source device, the ion source mounting chassis, and the electrode assembly are all provided with cavities as particle channels.

[0008] The electrode assembly includes a first cylindrical electrode, a second cylindrical electrode, and a third cylindrical electrode arranged coaxially in sequence; there is a gap between the ion source mounting chassis and the first end of the first cylindrical electrode to form a first electric field; there is a gap between the second end of the first cylindrical electrode and the first end of the second cylindrical electrode in the axial direction to form a second electric field; there is a gap between the second end of the second cylindrical electrode and the first end of the third cylindrical electrode in the axial direction to form a third electric field.

[0009] The potential of the ion source mounting chassis is higher than the potential of the first cylindrical electrode, and the potential of the second cylindrical electrode is higher than the potentials of the first cylindrical electrode and the third cylindrical electrode.

[0010] Preferably, the absolute values ​​of the potential difference of the second electric field and the potential difference of the third electric field are the same.

[0011] Preferably, an ultra-thin vacuum valve is provided between the second end of the first cylindrical electrode and the first end of the second cylindrical electrode to control the connection and isolation between the first cylindrical electrode and the second cylindrical electrode.

[0012] Preferably, the first end of the ultrathin vacuum valve is fixedly connected to the second end of the first cylindrical electrode, and the second electric field is between the first end of the ultrathin vacuum valve and the first end of the second cylindrical electrode.

[0013] Preferably, the ultra-thin vacuum valve includes a flange, a gland, an electrode cylinder, a movable lead screw, and a baffle plate. The flange is provided with a capsule-shaped limiting groove for accommodating the baffle plate. The baffle plate is disposed in the capsule-shaped limiting groove and connected to the movable lead screw. The movable lead screw adopts a lead screw and nut structure to drive the baffle plate to move along the axis within the capsule-shaped limiting groove, thereby changing the connection and disconnection state between the first cylindrical electrode and the second cylindrical electrode.

[0014] Preferably, the first cylindrical electrode includes a conical electrode head and a cylindrical electrode base, the electrode head and the electrode base being coaxially connected and communicating; the first electric field is between the electrode head and the ion source mounting chassis, and the electrode base is fixedly connected to the ultrathin vacuum valve.

[0015] Preferably, the electrode head is threadedly connected to the electrode seat, and the electrode seat is threadedly connected to the ultra-thin vacuum valve. This allows for adjustment of the gap between the electrode head and the ion source mounting chassis, changing the spacing of the gap lens, thereby adjusting the acceleration and focusing effect of particles in the first electric field, while also facilitating installation.

[0016] Preferably, the second cylindrical electrode is fixedly connected to a second electrode base, and the third cylindrical electrode is fixedly connected to a third electrode base, wherein both the second electrode base and the third electrode base are made of metal.

[0017] Preferably, an insulating ceramic ring is provided on the outside of the electrode assembly to isolate the electrode under high voltage; the second electrode base and the third electrode base are sealed to the insulating ceramic ring through indium wire to ensure the vacuum inside the electrode assembly and provide structural support to prevent deformation of the device from affecting the focusing effect of the ion beam.

[0018] Preferably, the electrode assembly has a first flange and a second flange at both ends. The first flange is fixedly connected to the ion source mounting chassis, and the second flange is coaxially arranged with the tail end of the third cylindrical electrode. A plurality of insulating tie rods are provided between the first flange and the second flange. One end of the insulating tie rod is threaded to the first flange, and the other end is fixedly connected to the second flange by fastening bolts.

[0019] Preferably, the ion source mounting chassis and the second cylindrical electrode are respectively connected to a positive high voltage loading device, and the first cylindrical electrode and the third cylindrical electrode are grounded.

[0020] By adopting the above technical solution, the beneficial effects of the present invention are as follows:

[0021] 1. This invention accelerates positively charged particles using a first electric field, rapidly increasing particle energy to over 30keV; furthermore, the particles are first focused using the first electric field, and then focused a second time using the second and third electric fields, achieving double focusing, which significantly improves the transmission efficiency of positive charges. Moreover, the entire device has a compact transmission structure and occupies little space, which is beneficial for the subsequent design of other system functions and the optimization of the overall size.

[0022] 2. The present invention provides an ultra-thin vacuum valve between the first cylindrical electrode and the second cylindrical electrode, which can isolate the vacuum and prevent damage to the vacuum environment in the subsequent system pipeline when disassembling and assembling the ion source, thereby further ensuring the ion transmission efficiency and taking up almost no space, keeping the overall structure small in size.

[0023] 3. This invention achieves energy regulation of ions by adjusting the positive high voltage applied to the ion source mounting chassis, thereby enabling ion focusing when adjusting the positive high voltage applied to the ion source chassis and the second electrode, facilitating control of particle acceleration and focusing effect; at the same time, the first cylindrical electrode is designed as a split two-section threaded connection, which can quickly adjust the distance between the ion source mounting chassis and the first cylindrical electrode, thereby achieving the purpose of adjusting the focusing effect. Attached Figure Description

[0024] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0025] Figure 1 This is a three-dimensional structural diagram of an embodiment of the present invention. Figure 1 ;

[0026] Figure 2 This is a three-dimensional structural diagram of an embodiment of the present invention. Figure 2 ;

[0027] Figure 3 This is a perspective sectional view of an embodiment of the present invention;

[0028] Figure 4 This is a front sectional view of an embodiment of the present invention;

[0029] Figure 5 This is a schematic diagram of the structure of an ultra-thin vacuum valve according to an embodiment of the present invention.

[0030] In the figure: 1. Ion source device; 2. Ion source chassis; 3. First cylindrical electrode; 4. Second cylindrical electrode; 5. Third cylindrical electrode; 6. Ultra-thin high vacuum valve; 7. Second electrode chassis; 8. Third electrode chassis; 9. Insulating ceramic ring; 10. First flange; 11. Second flange; 12. Insulating tie rod;

[0031] 301. Electrode head; 302. Electrode holder;

[0032] 601. Flange; 602. Gland; 603. Electrode cylinder; 604. Movable lead screw; 605. Barrier plate; 606. Capsule-shaped limiting groove. Detailed Implementation

[0033] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0034] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0035] Example 1

[0036] In one typical embodiment of this application, a positively charged particle acceleration and focusing device is provided, such as... Figures 1-5 As shown, it includes an ion source device 1, an ion source mounting chassis 2, and an electrode assembly. The ion source mounting chassis 2 is connected to the ion source device 1. There is a gap between the electrode assembly and the ion source mounting chassis 2. The ion source device 1, the ion source mounting chassis 2, and the electrode assembly are all provided with cavities as particle channels.

[0037] The electrode assembly includes a first cylindrical electrode 3, a second cylindrical electrode 4, and a third cylindrical electrode 5 arranged coaxially in sequence; there is a gap between the ion source mounting chassis 2 and the first end of the first cylindrical electrode 3 to form a first electric field; there is a gap between the second end of the first cylindrical electrode 3 and the first end of the second cylindrical electrode 4 along the axial direction to form a second electric field; there is a gap between the second end of the second cylindrical electrode 4 and the first end of the third cylindrical electrode 5 along the axial direction to form a third electric field;

[0038] The potential of the ion source mounting chassis 2 is higher than that of the first cylindrical electrode 3, and the potential of the second cylindrical electrode 4 is higher than that of the first cylindrical electrode 3 and the third cylindrical electrode 5.

[0039] Using the above structure, positively charged particles are accelerated and relatively gathered when passing through the first electric field, decelerated and relatively dispersed when passing through the second electric field, and accelerated and gathered again when passing through the third electric field. This achieves the acceleration and focusing of the particle beam, effectively avoiding beam loss caused by particle dispersion, improving the transmission efficiency of particles in the vacuum tube, and increasing the energy of accelerated particles to over 30keV.

[0040] Specifically, such as Figure 3 and Figure 4 As shown, the positively charged particle acceleration and focusing device of this embodiment includes, in sequence along the axial direction, an ion source device 1, an ion source mounting chassis 2, a first cylindrical electrode 3, an ultra-thin vacuum valve 6, a second cylindrical electrode 4, and a third cylindrical electrode 5, wherein the first cylindrical electrode, the second cylindrical electrode, and the third cylindrical electrode constitute an electrode assembly. Combined with... Figure 1 and Figure 2 As shown, a first flange 10 is coaxially mounted on the outer side of the head of the first cylindrical electrode 3, and a second flange 11 is coaxially mounted on the outer side of the tail of the third cylindrical electrode 5. The first flange 10 is coaxially mounted with the ion source mounting base 2 and is fixedly connected by self-tapping screws. The second flange 11 is fixedly connected to the first flange 10 by several insulating tie rods 12. Several insulating ceramic rings 9 are coaxially mounted on the outer side of the electrode assembly. The insulating ceramic rings 9 are installed between the first flange 10 and the second flange 11, which can insulate the first mounting flange, the second flange and each electrode base, and ensure the internal vacuum environment by indium wire sealing.

[0041] In this embodiment, the ion source device is a high-frequency positive ion source, capable of ionizing and generating positive ions. The ion source device is fixedly mounted on an ion source mounting chassis, such as... Figure 1 As shown, the ion source device 1 and the ion source mounting base 2 are coaxially arranged. An O-ring is provided between the ion source device 1 and the ion source mounting base 2 for sealing, and they are connected and fixed by self-tapping screws.

[0042] like Figure 3 and Figure 4 As shown, the electrode assembly behind the ion source mounting chassis includes three cylindrical electrodes with a main metal cylinder structure. From closest to furthest from the ion source mounting chassis, they are the first cylindrical electrode 3, the second cylindrical electrode 4, and the third cylindrical electrode 5. A certain gap exists along the axial direction between the ion source mounting chassis 2 and the first cylindrical electrode 3, as well as between adjacent cylindrical electrodes. Adjacent electrodes are insulated by a vacuum gap. In this embodiment, the ion source mounting chassis 2 and the second cylindrical electrode 4 are respectively connected to a positive high-voltage loading device, while the first cylindrical electrode 3 and the third cylindrical electrode 5 are respectively grounded. A positive potential difference is formed between the ion source mounting chassis and the first cylindrical electrode, a negative potential difference is formed between the first and second cylindrical electrodes, and a positive potential difference is formed between the second and third cylindrical electrodes, thus forming a first electric field, a second electric field, and a third electric field distributed sequentially. The first electric field has a gap lens structure, which can accelerate charged particles and increase their energy, while also acting as a lateral focusing effect. The second and third electric fields form a single-lens structure, focusing only on charged particles laterally without changing their energy. Through the aforementioned combined lens structure, the positive ions generated by the ion source device undergo a first longitudinal acceleration in the first electric field as they pass through the ion source mounting chassis, while the particle beam is deflected in the X and Y directions toward the axis. After the first acceleration, the ions undergo longitudinal deceleration in the second electric field after passing through the first cylindrical electrode, while the particle beam is deflected away from the axis in the X and Y directions. Then, after passing through the second cylindrical electrode, the ions undergo a second longitudinal acceleration in the third electric field, while the particle beam is deflected in the X and Y directions toward the axis. Finally, through the aforementioned single lens structure, the positive ions generated by the ion source are rapidly accelerated and focused, significantly reducing beam loss in the vacuum channel and greatly improving transmission efficiency.

[0043] In this embodiment, the axial distance between the first cylindrical electrode 3 and the second cylindrical electrode 4 is the same as the axial distance between the second cylindrical electrode 4 and the third cylindrical electrode 5, and the absolute value of the potential difference between the second electric field and the third electric field is the same. Furthermore, in this embodiment, the inner diameters of the three cylindrical electrodes are the same; therefore, the second and third electric fields are both parallel electrostatic fields and arranged axially symmetrically. Positively charged particles are decelerated by the second electric field and accelerated by the third electric field. Finally, after the first acceleration, the particles retain the same energy and velocity after passing through the subsequent two electric fields, and the particle beam achieves lateral symmetrical focusing in the X and Y planes.

[0044] like Figure 3 and Figure 4 As shown, the first cylindrical electrode 3 includes a conical electrode head 301 and a cylindrical electrode base 302. The electrode head 301 and the electrode base 302 are coaxially arranged and fixedly connected. The small-diameter end of the electrode head 301 is close to the ion source mounting base 2, and the large-diameter end of the electrode head 301 is connected to the electrode base 302, forming a continuous particle channel of conical and cylindrical components inside. In this embodiment, the ion source mounting base 2 and the small-diameter end of the electrode head 301 are coaxially arranged with an axial gap of 10mm. A positive voltage of 0-30kV is applied to the ion source mounting base, and the first cylindrical electrode is grounded, thereby forming a positive potential difference between the ion source mounting base and the first cylindrical electrode. When positively charged particles pass through the first electric field, they undergo the first longitudinal acceleration, and the first lateral focusing of the ion beam is achieved through electrostatic focusing.

[0045] In this embodiment, the outer wall of the electrode head 301 is machined with external threads, and the inner wall of the electrode seat 302 is machined with internal threads. The electrode head 301 and the electrode seat 302 are threadedly connected. The gap between the ion source mounting base and the first cylindrical electrode can be adjusted by the thread, thereby achieving the purpose of adjusting the focusing effect. In addition, the detachable structure of the threaded connection is convenient for assembly and disassembly.

[0046] like Figure 4 As shown, the ultra-thin vacuum valve 6 is coaxially mounted between the first cylindrical electrode 3 and the second cylindrical electrode 4. One end of the ultra-thin vacuum valve 6 is threadedly connected to the electrode seat 302 of the first cylindrical electrode 3, and the other end is close to the second cylindrical electrode 4, with a gap between them along the axial direction. In this embodiment, the ultra-thin vacuum valve 6 is an ultra-thin vacuum gate valve, the structure of which includes a flange 601, a gland 602, an electrode cylinder 603, a movable screw 604, and a baffle plate 605. The flange 601 has a cavity at its axial center, and a capsule-shaped limiting groove 606 communicating with the cavity is provided on one side of the cavity to accommodate the baffle plate 605. The baffle plate 605 is disposed in the capsule-shaped limiting groove 606 and connected to the movable screw 604. The movable screw 604 adopts a screw-nut structure, which can drive the baffle plate to move linearly along the radial direction of the flange within the capsule-shaped limiting groove, thereby changing the connection and disconnection state between the first cylindrical electrode and the second cylindrical electrode. Specifically, when the baffle plate moves to the flange axis, it seals the cavity, thereby blocking the particle channel and achieving vacuum isolation. When the baffle plate moves away from the flange axis, ions can pass through the cavity and enter the second electric field. In this embodiment, the ultra-thin vacuum valve isolates the vacuum by moving the baffle plate through a movable screw, which effectively avoids the impact of ion source disassembly and assembly on the vacuum environment, ensuring the ultra-vacuum environment of the particle channel and thus improving particle transport efficiency. At the same time, the ultra-thin vacuum valve has a small thickness, does not increase the overall device volume, and can maintain a compact structure and small size.

[0047] Combination Figure 5 As shown, a pressure cap 602 is provided on one side of the capsule-shaped limiting groove 606, and the shape of the pressure cap 602 matches the shape of the barrier plate 605. In this embodiment, the barrier plate 605 is an irregular cylinder, and the top surface of the cylinder forms a slope, so that the thickness of the cylinder gradually increases from left to right in the radial direction. The bottom surface of the pressure cap 602 forms a slope, so that the thickness of the pressure cap gradually decreases from left to right in the radial direction. The slope of the top surface of the barrier plate and the slope of the bottom surface of the pressure cap match, thereby ensuring that the barrier plate can cooperate with the pressure cap to seal the cavity of the ultra-thin vacuum valve and achieve vacuum isolation.

[0048] The pressure cap 602 is disposed on one side of the capsule-shaped limiting groove 606 and is fixedly connected to the flange 601 by self-tapping screws. The end of the pressure cap 602 away from the capsule-shaped limiting groove is machined with external threads, which can be threadedly connected to the first cylindrical electrode 3 for easy installation and fixation. An electrode cylinder 603 is disposed on the other side of the capsule-shaped limiting groove. The electrode cylinder 603 is fixedly connected to the flange 601 by self-tapping screws. The inner diameter of the electrode cylinder 603 is the same as the inner diameter of the first cylindrical electrode 3 and the second cylindrical electrode 4.

[0049] In this embodiment, as Figure 4 As shown, the second electric field is between the electrode cylinder 603 of the ultra-thin vacuum valve and the second cylindrical electrode 4, with a gap of 10 mm. The third electric field is between the second cylindrical electrode 4 and the third cylindrical electrode 5, with a gap of 10 mm. The second cylindrical electrode 4 is connected to a positive 0-30kV high-voltage loading device, while the first cylindrical electrode 3 and the third cylindrical electrode 5 are grounded. Positively charged particles accelerated by the first electric field decelerate longitudinally when passing through the second electric field, causing the ion beam to diverge laterally. Upon passing through the third electric field, they accelerate longitudinally back to their pre-deceleration velocity, and the ion beam becomes laterally focused. This entire acceleration and focusing process effectively avoids beam loss caused by particles diverging onto the vacuum wall within the particle channel, significantly improving particle transport efficiency.

[0050] As shown in the figure, the main bodies of both the second cylindrical electrode 4 and the third cylindrical electrode 5 are designed as cylinders with a diameter of 80 mm and a length of 80 mm. A second electrode base 7 is coaxially fixed to the outside of the second cylindrical electrode 4, and a third electrode base 8 is coaxially fixed to the outside of the third cylindrical electrode 5. The second and third cylindrical electrodes are installed and fixed using these bases. Several ventilation holes are provided on both the second and third electrode bases 7 and 8, which can be connected to external gas pipes for vacuuming, creating a vacuum environment for the ion channel within the particle acceleration and focusing device of this embodiment. The second electrode base is welded to the outer surface of the second cylindrical electrode, and the third electrode base is welded to the outer surface of the third cylindrical electrode.

[0051] In this embodiment, as Figures 1-3As shown, four identical insulating ceramic rings 9 are coaxially arranged on the outer periphery of the electrode assembly. These rings are used to fill the spaces between the first flange and the ultra-thin vacuum valve, between the ultra-thin vacuum valve and the second electrode base, between the second electrode base and the second flange, and between adjacent electrode bases. This isolates the electrodes under high pressure and provides structural support. Indium wires are used between each insulating ceramic ring and the adjacent structure to achieve a vacuum seal.

[0052] In this embodiment, combined with Figures 1-3 As shown, the first flange 10 and the second flange 11 are evenly provided with several corresponding threaded holes. The first flange 10 and the second flange 11 are fixedly connected by several parallel insulating rods 12. The first end of the insulating rod 12 is threaded to the first flange 10, and the second end is fixedly connected to the second flange 11 by fastening bolts and nuts. A flat washer is provided between the nut and the second flange 11 to protect the connection surface. With the above structure, the first flange, the insulating rods and the second flange are pressed and fixed by the fastening bolts and nuts, which allows the first flange and the second flange to press the insulating ceramic ring and the indium wire on the electrode base plate in the middle from both sides, improving the stability of the insulation seal.

[0053] In this embodiment, the insulating tie rod is made of G10 material, which can withstand great force without being damaged or deformed, and is not permeable by water vapor or liquid. It has the characteristics of insulation, acid and alkali resistance, and light weight. The insulating tie rod is connected between the first flange and the second flange and is used to tighten the indium wire and fix the electrode base, insulating ceramic ring and other components, effectively realizing the vacuum sealing of the internal ion channel.

[0054] The positively charged particle acceleration and focusing device in this embodiment can adjust the particle acceleration energy by adjusting the positive high voltage applied to the ion source mounting chassis, and can jointly adjust the focusing effect of positive ions by adjusting the positive high voltage applied to the ion source chassis and the second cylindrical electrode; at the same time, the vacuum isolation within the electrode assembly is achieved through an ultra-thin vacuum valve, which can effectively ensure that the internal vacuum environment is not disrupted. Using the above scheme, the transmission efficiency of positively charged particles within the vacuum channel is significantly improved.

[0055] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Those skilled in the art should understand that the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A positively charged particle acceleration and focusing device, characterized in that, The device includes an ion source device, an ion source mounting chassis, and an electrode assembly. The ion source mounting chassis is connected to the ion source device, and there is a gap between the electrode assembly and the ion source mounting chassis. The ion source device, the ion source mounting chassis, and the electrode assembly are all provided with cavities as particle channels. The electrode assembly includes a first cylindrical electrode, a second cylindrical electrode, and a third cylindrical electrode arranged coaxially in sequence, and the first cylindrical electrode, the second cylindrical electrode, and the third cylindrical electrode have the same inner diameter; the first cylindrical electrode includes a conical electrode head and a cylindrical electrode seat, and the electrode head and the electrode seat are coaxially connected and communicate with each other; A gap exists between the ion source mounting chassis and the electrode head, forming a first electric field; an ultra-thin vacuum valve is provided between the electrode base and the first end of the second cylindrical electrode to control the connection and isolation between the first and second cylindrical electrodes; the first end of the ultra-thin vacuum valve is fixedly connected to the electrode base, and a gap exists along the axial direction between the second end of the ultra-thin vacuum valve and the first end of the second cylindrical electrode, forming a second electric field; a gap exists along the axial direction between the second end of the second cylindrical electrode and the first end of the third cylindrical electrode, forming a third electric field. The potential of the ion source mounting chassis is higher than the potential of the first cylindrical electrode, and the potential of the second cylindrical electrode is higher than the potentials of the first cylindrical electrode and the third cylindrical electrode.

2. The positively charged particle acceleration and focusing device as described in claim 1, characterized in that, The absolute value of the potential difference of the second electric field is the same as that of the potential difference of the third electric field.

3. The positively charged particle acceleration and focusing device as described in claim 1, characterized in that, The ultra-thin vacuum valve includes a flange, a gland, an electrode cylinder, a movable lead screw, and a baffle plate. The flange has a capsule-shaped limiting groove for accommodating the baffle plate. The baffle plate is disposed in the capsule-shaped limiting groove and connected to the movable lead screw. The movable lead screw adopts a lead screw and nut structure to drive the baffle plate to move along the axis within the capsule-shaped limiting groove, thereby changing the connection and disconnection state between the first cylindrical electrode and the second cylindrical electrode.

4. The positively charged particle acceleration and focusing device as described in claim 1, characterized in that, The electrode head is threadedly connected to the electrode seat, and the electrode seat is threadedly connected to the ultra-thin vacuum valve.

5. The positively charged particle acceleration and focusing device as described in claim 1, characterized in that, The second cylindrical electrode is fixedly connected to a second electrode base, and the third cylindrical electrode is fixedly connected to a third electrode base. Both the second electrode base and the third electrode base are made of metal.

6. The positively charged particle acceleration and focusing device as described in claim 5, characterized in that, An insulating ceramic ring is provided on the outside of the electrode assembly. The second electrode base and the third electrode base are sealed to the insulating ceramic ring by indium wire to ensure the vacuum inside the electrode assembly and provide structural support, so as to prevent the device from deforming and affecting the focusing effect of the ion beam.

7. The positively charged particle acceleration and focusing device as described in claim 1, characterized in that, The electrode assembly is provided with a first flange and a second flange at both ends. The first flange is fixedly connected to the ion source mounting chassis, and the second flange is coaxially arranged with the tail end of the third cylindrical electrode. A plurality of insulating tie rods are provided between the first flange and the second flange. One end of the insulating tie rod is threaded to the first flange, and the other end is fixedly connected to the second flange by fastening bolts.

8. The positively charged particle acceleration and focusing device as described in claim 2, characterized in that, The ion source mounting chassis and the second cylindrical electrode are respectively connected to a positive high voltage loading device, and the first cylindrical electrode and the third cylindrical electrode are grounded.

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