ECR ion source capable of generating high-current alpha particles and H2 < + > particles
By using variable material discharge chambers, dynamic variable multimodal constraining magnets and adjustable position solenoid coils in the ECR ion source, the problem of sharing a set of ion source system to produce α particles and H2+ particles in time is solved, and the particle production with high proportion and high stability is achieved, meeting the magnetic constraint requirements of medium-charged α particles.
Patent Information
- Application Number
- CN202411830824.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-12-09
- Filing Date
- 2024-12-12
- Publication Date
- 2025-02-25
AI Technical Summary
When using a low-frequency 2.45GHz ECR ion source system to produce α particles and H2+ particles in time, it is difficult to take into account the needs of impurity separation, increased particle proportion and engineering costs. In particular, the requirements for the magnetic constraints of ion sources in medium-charged states are stricter.
An ECR ion source including a variable material discharge cavity, a dynamic variable multimodal constrained magnet and a solenoid coil with adjustable position was designed. By adjusting the magnet system and the inner wall material of the discharge cavity, the production conditions of α particles and H2+ particles were optimized respectively.
It is achieved when producing α particles and H2+ particles, while increasing the proportion of particles, while meeting the magnetic constraint requirements of medium-charged α particles, reducing engineering costs, and improving the operating stability of the ion source.
Smart Images
Figure CN119521517A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of cyclotron accelerators, and in particular relates to an ECR ion source capable of generating high-current alpha particles and H2+ particles. Background Art
[0002] Multiply charged ions (MCIs) are necessary to increase the output energy of accelerator particles. Alpha particle accelerators are used in the production of 211At drugs. H2+ particles can also be used for accelerator debugging and high-current proton accelerators. H2+ ion beams can also be used for proton cancer treatment.
[0003] Compared with high-frequency ECR ion sources with large source sizes, it is more economical to manufacture low-frequency (such as 2.45GHz) ECR sources. The 2.45GHz ECR ion source has the advantages of compact structure, long life, stable source operation and low economic cost. The 2.45GHz ECR ion source can generate different magnetic field configurations, and the 2.45GHz ECR ion source has achieved remarkable results in generating singly charged positive ions based on the axial resonance field alone. Due to its outstanding advantages, some researchers suggest using the 2.45GHz ECR ion source to generate medium-charged ion beams.
[0004] In order to improve the output energy of accelerator particles, technical personnel in this field have tried to use a common low-frequency 2.45 GHz ECR ion source system to produce two different particles (α particles and H2+ particles) to improve the output energy of accelerator particles. Since it is very difficult to produce two different particles by using a common ion source system and mixed gas, the method of using a common ion source system to produce α particles and H2+ particles in a time-sharing manner is generally adopted.
[0005] One of the difficulties in using a common ion source system to produce α particles and H2+ particles in a time-sharing manner is that the α particles and H2+ particles produced by the ion source are not all the expected particles, and there are relatively more impurities, so the proportion of α particles and H2+ particles in the mixed beam is low. For example, when helium is passed through the ion source to produce α particles, what is actually produced is not α particles but a mixed beam, in which the proportion of α particles is at most about 10%, while He+ accounts for about 90%; when hydrogen is passed through the ion source to produce H2+ particles, what is actually produced is not just H2+ particles but a mixed beam, in which the proportion of H2+ particles in the mixed beam is only 30%-40%, while H+ and H3+ account for a relatively large proportion;
[0006] The second difficulty in sharing a set of ion source systems to produce α particles and H2+ particles in a time-sharing manner is that the production of medium-charged α particles requires more stringent ion source magnetic confinement, while the production of H2+ particles requires relatively lower ion source magnetic confinement. Therefore, sharing a set of ion source systems cannot meet the personalized needs of producing α particles.
[0007] In short, the difficulty of using a common ion source system to produce α particles and H2+ particles in a time-sharing manner is to not only meet the requirements of separating impurities with one ion source, but also to increase the ratio of α particles and H2+ particles and meet the requirements of engineering costs. Secondly, the production of medium-charged α particles places more stringent requirements on the magnetic confinement of the ion source. Summary of the invention
[0008] In view of the problems existing in the prior art, the present invention proposes an ECR ion source capable of producing high-current α particles and H2+ particles. The purpose is to solve the problem of having to take into account the need to separate impurities with one ion source, while also increasing the proportion of α particles and H2+ particles, and having more stringent requirements for the magnetic confinement of the ion source when a set of ion source system is used to produce α particles and H2+ particles in a time-sharing manner, as well as the problem of having to produce α particles in a medium-charge state.
[0009] The present invention proposes the following technical solutions to solve the technical problems:
[0010] An ECR ion source capable of generating high-current α particles and H2+ particles comprises: a microwave system (1), a discharge cavity (2), and an extraction structure (4) arranged in sequence along the axial direction, and a magnet system (3) and an adjustment device (5) arranged in sequence along the radial direction of the discharge cavity (2); the magnet system (3) comprises a multi-peak confinement magnet (3-3) arranged outside the discharge cavity (2) and solenoid coils (3-1) and (3-2) arranged outside the multi-peak confinement magnet (3-3); the inner diameter and outer diameter of the solenoid coils (3-1) and (3-2) are the same; the invention is characterized in that:
[0011] The discharge chamber (2) is a discharge chamber (2) with variable materials; the multi-peak confinement magnet (3-3) is a dynamically variable multi-peak confinement magnet (3-3); and the solenoid coils (3-1) and (3-2) are electromagnetic coils with adjustable positions.
[0012] Furthermore, the discharge chamber (2) is a discharge chamber (2) with variable materials, that is, the material of the discharge chamber is copper or tantalum with a high recombination coefficient, and when α particles are generated, the material of the inner wall of the discharge chamber is copper, and when H2+ particles are generated, the material of the inner wall of the discharge chamber is tantalum.
[0013] Furthermore, the multi-peak confinement magnet (3-3) is a dynamically variable multi-peak confinement magnet (3-3), that is, when generating α particles, the magnet system (3) is composed of the multi-peak confinement magnet (3-3) and the solenoid coils (3-1) and (3-2); when generating H2+ particles, the magnet system (3) is only composed of the solenoid coils (3-1) and (3-2).
[0014] Furthermore, the solenoid coils (3-1) and (3-2) are electromagnetic coils with adjustable positions, that is, the solenoid coil (3-2) is arranged on an adjusting device (5), and the adjusting device (5) is composed of a retaining frame (5-1), two screws (5-2), and four nuts (5-3). Each screw (5-2) is equipped with two nuts (5-3). When the nuts (5-3) are rotated, the nuts (5-3) move axially along the screws, and the nuts (5-3) clamp the retaining frame of the solenoid coil (3-2) to limit the position of the solenoid coil (3-2).
[0015] Furthermore, the number of the dynamically variable multi-peak confinement magnets (3-3) is 12; their length is the length of the discharge chamber, and their cross-section is 9×13 mm.
[0016] Furthermore, the 12 multi-peak confinement magnets (3-3) are of N42SH grade and have a residual magnetism of 1.39T, providing a multi-peak tangent magnetic field with a maximum field strength of about 5000Gs on the wall of the discharge chamber.
[0017] Furthermore, the magnetization direction of the multi-peak confinement magnet (3-3) is along the radial direction, and two groups of multi-peak confinement magnets with opposite magnetization directions are fixed in a clip device (6), and the number of clips is 6.
[0018] Furthermore, the distance between the solenoid coils has an adjustment range of 0 to 28 mm.
[0019] Furthermore, when the solenoid coils are farthest apart, the magnetic field at the outlet is at the second peak of the double-peak magnetic field curve; the double-peak curve is a curve formed by the solenoid coils (3-1) and (3-2); the second peak of the double-peak magnetic field curve is the second peak far away from the center point of the coordinate axis of the double-peak curve.
[0020] Advantages and effects of the present invention
[0021] 1. The present invention generates α particles while taking into account H2+ particles. When generating α particles, multi-peak confinement magnets are added to enhance magnetic confinement and increase the proportion of α particles; when generating H2+ particles, multi-peak confinement magnets are removed, and the inner wall of the discharge chamber is made of tantalum with a high composite coefficient, so that the content of hydrogen molecules in the discharge chamber increases, the content of hydrogen atoms in the plasma decreases, and thus the proportion of H2+ particles increases.
[0022] 2. By fixing one solenoid coil, changing the position of the other coil, and adjusting the axial resonant magnetic field by changing the ampere-turns, the magnetic field modulation range can cover all magnetic field configurations required for electron cyclotron resonance to occur, so as to explore the key technologies for increasing the proportion of alpha particles and H2+ particles and obtain the optimal parameter combination for ion source operation.
[0023] 3. The α particles and H2+ particles produced by the present invention will meet the development needs of subsequent cyclotron accelerators. At present, there is no independently developed α accelerator in China. An ECR ion source is used to achieve double-beam high-brightness combined injection of α particles and H2+ particles. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 It is a cross-sectional view of the basic structure of the 2.45HzECR ion source;
[0025] Figure 2 It is a schematic diagram of a clip device for placing multi-peak constraining magnets of the present invention;
[0026] Figure 3 is a schematic diagram of a regulating device between two solenoid coils;
[0027] Figure 4 Schematic diagram of the multi-peak confinement field of the ECR ion source;
[0028] Figure 5 It is a two-dimensional cross-sectional diagram of the entire magnet system in the xy plane.
[0029] Figure 6 This is a double-peak curve when the two coils are farthest apart and the excitation current is maximum.
[0030] In the figure, Φ50: inner wall of the discharge chamber; Φ53: outer wall of the discharge chamber; Φ81: inner wall of the clip; Φ85: outer wall of the clip and inner wall of the ion source outer tube (the two are tightly attached); Φ90: outer wall of the ion source outer tube; Φ106: coil shell; Φ110: inner diameter of the coil. DETAILED DESCRIPTION
[0031] Design principle of the present invention
[0032] 1. The original intention of the invention is to solve the problem of optimal proportion 。
[0033] 2. Innovations of the present invention: One of the innovations: Under different experimental conditions, the structure can be used to find the best combination of ion source operating parameters to obtain the best ratio of He2+ (α particles) and H2+ particles. Under the different experimental conditions, the structure can be used to find the best combination of ion source operating parameters, that is: when producing α particles, adjust the position of the coil and the size of the current, and use a multi-peak field to constrain, so as to obtain the best ratio of α particles; when producing H2+ particles, adjust the position of the coil and the size of the current, and replace the inner wall material of the discharge chamber with tantalum, so as to obtain the best ratio of H2+ particles. The second innovation: the optimized design of the ion source, that is, while minimizing the size and total weight of the ion source to the greatest extent, complete the design of the permanent magnetic confinement field and the layout of the two electromagnetic coils and the discharge chamber to meet the requirements of plasma generation and confinement.
[0034] 3. Design principles of the present invention: First, when generating H2+ particles, since H2+ particles only carry one unit positive charge, the effect of multi-peak field constraint can be explored by replacing the clip to see whether the current intensity of the obtained H2+ particles can be increased; in addition, the high composite coefficient tantalum material on the inner wall of the discharge chamber increases the content of hydrogen molecules in the discharge chamber, and the probability of collision between electrons and hydrogen molecules increases, thereby increasing the proportion of H2+ particles; the position of the electromagnetic coil and the change of the excitation current can be adjusted to ensure that we can obtain any desired resonant field type in order to maximize the resonant area in the discharge chamber. Second, when generating α particles, since α particles carry two units of positive charge, they need to collide twice step by step. Moreover, the ionization energy required for helium is higher than that for hydrogen, so stronger magnetic constraint is required. Modern ECR generally uses a sextupole field or an octupole field to provide radial confinement. This time, six pairs of adjacent permanent magnets with opposite magnetization directions are used to provide the required multi-peak confinement field. Six permanent magnets alone can produce strong confinement, but the regional magnetic confinement between adjacent magnets is weak, so another six magnets are added to form six pairs of enhanced magnetic confinement. The field strength of the entire discharge chamber inner wall is above 4000Gs; in addition, the position of the electromagnetic coil and the change of the excitation current can be adjusted to ensure that we can obtain any required resonance field type in order to maximize the resonance area in the discharge chamber.
[0035] Based on the above principle, the present invention designs an ECR ion source capable of generating strong current α particles and H2+ particles, such as Figure 1-5 As shown, it comprises: a microwave system 1, a discharge cavity 2, and an extraction structure 4 arranged in sequence along the axial direction, and a magnet system 3 and an adjustment device 5 arranged in sequence along the radial direction of the discharge cavity 2; the magnet system 3 comprises a multi-peak confinement magnet 3-3 arranged outside the discharge cavity 2 and solenoid coils 3-1 and 3-2 arranged outside the multi-peak confinement magnet 3-3; the inner diameter and outer diameter of the solenoid coils 3-1 and 3-2 are the same; its characteristics are:
[0036] The discharge chamber 2 is a discharge chamber 2 with variable materials; the multi-peak confinement magnet 3-3 is a dynamically variable multi-peak confinement magnet 3-3; and the solenoid coils 3-1 and 3-2 are electromagnetic coils with adjustable positions.
[0037] Furthermore, the discharge chamber 2 is a discharge chamber 2 with variable materials, that is, the material of the discharge chamber is copper or tantalum with a high composite coefficient, the material of the inner wall of the discharge chamber is copper when generating α particles, and the material of the inner wall of the discharge chamber is copper when generating H2 + When the particles are formed, the material of the inner wall of the discharge chamber is tantalum.
[0038] Furthermore, the multi-peak confinement magnet 3-3 is a dynamically variable multi-peak confinement magnet 3-3, that is, when generating α particles, the magnet system 3 is composed of the multi-peak confinement magnet 3-3 and the solenoid coils 3-1 and 3-2. +When the particles are formed, the magnetic system 3 is composed only of the solenoid coils 3-1 and 3-2.
[0039] Furthermore, the solenoid coils 3-1 and 3-2 are electromagnetic coils with adjustable positions, that is, the solenoid coil 3-2 is arranged on the adjusting device 5, and the adjusting device 5 is composed of a retaining frame 5-1, two screws 5-2, and four nuts 5-3. Each screw 5-2 is equipped with two nuts 5-3. When the nut 5-3 is rotated, the nut 5-3 moves axially along the screw. The nut 5-3 clamps the retaining frame of the solenoid coil 3-2 to limit the position of the solenoid coil 3-2.
[0040] Furthermore, if Figure 4 As shown, the number of the dynamically variable multi-peak confinement magnets 3-3 is 12; their length is the length of the discharge chamber, and their cross-section is 9×13 mm.
[0041] Furthermore, if Figure 4 As shown, the 12 multi-peak confinement magnets (3-3) are of N42SH grade with a residual magnetism of 1.39T, and provide a multi-peak tangent magnetic field with a maximum field strength of about 5000Gs on the wall of the discharge chamber.
[0042] Furthermore, if Figure 2 As shown, the magnetization direction of the multi-peak confinement magnet 3-3 is along the radial direction, and two groups of multi-peak confinement magnets with opposite magnetization directions are fixed in a clip device 6, and the number of clips is 6.
[0043] Furthermore, if Figure 3 As shown, the distance between the solenoid coils has an adjustment range of 0 to 28 mm.
[0044] Furthermore, if Figure 6 As shown, when the solenoid coils are farthest apart, the magnetic field at the outlet is at the second peak of the double-peak magnetic field curve; the double-peak curve is the curve formed by the solenoid coils 3-1 and 3-2; the second peak of the double-peak magnetic field curve is the second peak far away from the center point of the coordinate axis of the double-peak curve.
[0045] Embodiment 1
[0046] like Figure 1 As shown, the structure of the ECR ion source that can produce α particles and H2+ particles is: 1: microwave system; 2: discharge cavity; 3: magnet system (including solenoid coils 3-1, 3-2 and multi-peak confinement magnet 3-3); 4: extraction structure; 5: adjustment device.
[0047] 2.45GHz microwaves are fed into the discharge cavity through the microwave system to generate plasma by resonance heating. The multi-peak confinement magnet provides a radial confinement magnetic field to confine the plasma, and α particles and H2+ particles are extracted through the extraction structure.
[0048] like Figure 2 As shown, the multi-peak confinement field is provided by 6 pairs of permanent magnets with magnetization directions along the radial direction. The magnets with opposite magnetization directions are arranged alternately and fixed in the water cooling tank between the discharge chamber and the solenoid coil by the clip 6. The magnetic field on the inner wall of the discharge chamber is close to 5000Gs.
[0049] like Figure 3 As shown, the adjustment device 5 between the two solenoid coils of the present invention changes the distance between the two solenoid coils through the adjustment device 5 to achieve an adjustment range of the axial resonant magnetic field of 800 to 1000 Gs.
[0050] It should be emphasized that the above specific embodiments are merely explanations of the present invention, and they are not limitations of the present invention. After reading this specification, those skilled in the art can make modifications to the above embodiments without any creative contribution as needed, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.
Claims
1. An ECR ion source capable of generating high-current α particles and H2+ particles, comprising: A microwave system (1), a discharge cavity (2), and an extraction structure (4) are sequentially arranged along the axial direction, and a magnet system (3) and an adjustment device (5) are sequentially arranged along the radial direction of the discharge cavity (2); the magnet system (3) comprises a multi-peak confinement magnet (3-3) arranged outside the discharge cavity (2) and solenoid coils (3-1) and (3-2) arranged outside the multi-peak confinement magnet (3-3); the inner diameter and outer diameter of the solenoid coils (3-1) and (3-2) are the same; and the characteristics are: The discharge chamber (2) is a discharge chamber (2) with variable materials; the multi-peak confinement magnet (3-3) is a dynamically variable multi-peak confinement magnet (3-3); and the solenoid coils (3-1) and (3-2) are electromagnetic coils with adjustable positions.
2. An ECR ion source capable of generating high-current α particles and H2+ particles according to claim 1, characterized in that: The discharge chamber (2) is a discharge chamber (2) with variable materials, that is, the material of the discharge chamber is copper or tantalum with a high recombination coefficient, the material of the inner wall of the discharge chamber is copper when α particles are generated, and the material of the inner wall of the discharge chamber is copper when H2 is generated. + When the particles are formed, the material of the inner wall of the discharge chamber is tantalum.
3. An ECR ion source capable of generating high-current α particles and H2+ particles according to claim 1, characterized in that: The multi-peak confinement magnet (3-3) is a dynamically variable multi-peak confinement magnet (3-3), that is, when generating α particles, the magnet system (3) is composed of the multi-peak confinement magnet (3-3) and the solenoid coils (3-1) and (3-2). + When the particles are formed, the magnetic system (3) is composed only of the solenoid coils (3-1) and (3-2).
4. The ECR ion source capable of generating high-current α particles and H2+ particles according to claim 1, characterized in that: The solenoid coils (3-1) and (3-2) are electromagnetic coils with adjustable positions, that is, the solenoid coil (3-2) is arranged on an adjusting device (5), and the adjusting device (5) is composed of a retaining frame (5-1), two screw rods (5-2), and four nuts (5-3). Each screw rod (5-2) is equipped with two nuts (5-3). When the nuts (5-3) are rotated, the nuts (5-3) move axially along the screw rods. The nuts (5-3) clamp the retaining frame of the solenoid coil (3-2) to limit the position of the solenoid coil (3-2).
5. The ECR ion source capable of generating high-current α particles and H2+ particles according to claim 1, characterized in that: The number of the dynamically variable multi-peak confinement magnets (3-3) is 12; their length is the length of the discharge chamber, and their cross-section is 9×13 mm.
6. An ECR ion source capable of generating high-current α particles and H2+ particles according to claim 5, characterized in that: The 12 multi-peak confinement magnets (3-3) are of N42SH grade and have a residual magnetism of 1.39T. They provide a multi-peak tangent magnetic field with a maximum field strength of about 5000Gs on the wall of the discharge chamber.
7. The ECR ion source capable of generating high-current α particles and H2+ particles according to claim 1, characterized in that: The magnetization direction of the multi-peak confinement magnet (3-3) is along the radial direction, and two groups of multi-peak confinement magnets with opposite magnetization directions are fixed in a clip device (6), and the number of clips is 6.
8. The ECR ion source capable of generating high-current α particles and H2+ particles according to claim 1, characterized in that: The distance between the solenoid coils has an adjustment range of 0 to 28 mm.
9. The ECR ion source capable of generating high-current α particles and H2+ particles according to claim 1, characterized in that: When the solenoid coils are farthest apart, the magnetic field at the outlet is at the second peak of the double-peak magnetic field curve; the double-peak curve is a curve formed by the solenoid coils (3-1) and (3-2); the second peak of the double-peak magnetic field curve is the second peak far away from the center point of the coordinate axis of the double-peak curve.