A device for wide-range regulation of the beam current of a cyclotron

Abstract

The application provides a device for adjusting the beam current of a cyclotron, which is arranged between an ion source and the cyclotron and comprises a magnetic solenoid for adjusting the divergence or focusing state of the beam, and two sets of beam blockers for blocking the beam and reducing the beam current passing through, the two sets of beam blockers being arranged on the two sides of the magnetic solenoid. The application provides a novel front-end cooperative regulation architecture of'magnetic regulation + double-stage mechanical current limiting', which fundamentally resolves the contradiction between 'engineering safety' and 'control precision' in the conventional technology. The beam current is precisely adjusted by several orders of magnitude (especially in the pA level), and the performance boundary of the prior art is broken. Through the system design, the limit precision requirement of the key components is reduced, and the engineering implementation of the high-performance beam regulation system is more simple, economical and reliable.

Description

Technical Field

[0001] This invention belongs to the field of cyclotron technology, and particularly relates to a device for adjusting the beam intensity of a cyclotron over a wide range. Background Technology

[0002] Compact negative hydrogen cyclotrons are widely used in industries such as industry, nuclear medicine, and aerospace. For different applications, a wide range of accelerator beam current adjustment is required, spanning nine orders of magnitude. The goal of this wide-range adjustment of the cyclotron beam current is to control the flow rate of a "super faucet," requiring both precise output of a single drop (pA level) and the ability to generate a full-power fire-fighting jet (mA level).

[0003] Existing technologies offer two methods, but each method has serious drawbacks: Existing Technology 1: "Throttling" at the high-pressure water pipe and adjusting at the accelerator back end. The mainstream cyclotron current intensity adjustment method is a combination of adjusting ion source parameters and beam transmission line adjustment to change the beam intensity reaching the application terminal (the ion source is an external ion source independent of the main cyclotron accelerator body, and its output beam is injected into the accelerator through the transmission line). The ion source current intensity adjustment range is 100 μA~10 mA, and after passing through the cyclotron, it is extracted to about 10 μA~1 mA. Multiple online adjustment beam clamps need to be arranged on the beam transmission line to achieve a wide current intensity adjustment range of 1 pA-1 mA. The disadvantage of this method is that the beam from the ion source has high energy after being accelerated by the accelerator, and the online adjustment beam clamps on the beam transmission line need to block the 10 μA-level high-energy proton beam; on the one hand, such a high-energy beam intensity is lost in the beam clamps, resulting in a relatively serious dose and difficult maintenance in the later stage; on the other hand, the beam clamps generate a lot of heat, requiring a complex water-cooling structure, and the manufacturing of the beam clamps is a major engineering challenge.

[0004] Existing technology 2: "Flow restriction" at the source inlet (accelerator front-end adjustment - as in patent 1). Patent 1 (title: Adjustment device and method for extracting beams below nA from a cyclotron, cyclotron; publication number: CN 110891360 A) discloses a wide-range beam adjustment method for beam clamping on the injection line of a cyclotron, which can extract beams below nA. This method clamps the beam before it enters the cyclotron, avoiding the need to clamp high-current beams on the beam transmission line. However, for a single clamping device to achieve wide-range beam current adjustment, the motion control precision (0.01mm level) of the clamping device is extremely high, making it extremely difficult to achieve when facing the requirement of 1pA-level beam current intensity.

[0005] In summary: Existing technology 1, back-end throttling, solves the control precision problem because valve adjustment is relatively easy, but introduces engineering safety and complexity issues, such as high energy loss, radiation, and cooling. Existing technology 2, front-end flow limiting, solves the engineering safety problem and eliminates high energy loss, but shifts the challenge to the limits of mechanical and control precision, making it difficult to achieve stable and reliable control over a wide range, especially at extremely low flow intensities. Summary of the Invention

[0006] This invention addresses the problems existing in the prior art by proposing a device for adjusting the beam intensity of a cyclotron accelerator over a wide range. The purpose is to address the issues of back-end throttling, which would lead to engineering safety and complexity; and front-end current limiting, which would shift the challenge to the limits of mechanical and control precision, making it difficult to achieve a wide range of applications.

[0007] A device for wide-range adjustment of cyclotron beam intensity is characterized in that: the device consists of a magnetic solenoid arranged between the ion source and the cyclotron and two sets of beam clamps. The magnetic solenoid is used to adjust the divergence or focusing state of the beam, and the two sets of beam clamps are used to block the beam and reduce the beam intensity. The two sets of beam clamps are arranged on both sides of the magnetic solenoid.

[0008] Furthermore, the two sets of beam clamps have the same structure, each consisting of four movable graphite plates, referred to as the upper beam clamp, lower beam clamp, left beam clamp, and right beam clamp respectively. By adjusting the up-and-down movement of the upper and lower beam clamps and the left-and-right movement of the left and right beam clamps, the square area through which the beam passes through the slit is changed, thereby reducing the beam intensity.

[0009] Furthermore, the motion positioning accuracy requirement for these four card bundle blocks is 0.1 mm.

[0010] Furthermore, the beam is extracted from the ion current, and by adjusting the ion source parameters, the ion source can extract a current intensity of 100 μA to 10 mA.

[0011] Furthermore, the distance between the beam clamp 1 and the ion source outlet is 50cm-100cm. By adjusting the beam current through the slit area of ​​the beam clamp 1, the beam current passing through the beam clamp 1 can be reduced to a maximum of 1 / 10000 of the original.

[0012] Furthermore, the beam current passing through the beam clamp 2 can be reduced to a maximum of 1 / 10000 of its original value.

[0013] Furthermore, by adjusting the ion source to extract a minimum beam current of 100 μA, the minimum beam current after passing through clamp 1 is 100 μA / 10000=10nA, and the minimum beam current after passing through clamp 2 is 10nA / 10000=1pA. Since 90% of the beam current is lost during the injection and acceleration process in the cyclotron, meaning the cyclotron can extract a beam with a current of 1 / 10 of the injection current, when the minimum beam current after passing through clamp 2 is 10nA / 10000=1pA, a minimum beam current of 0.1pA can be extracted after injection into the cyclotron.

[0014] Furthermore, by adjusting the ion source to extract a maximum beam current of 10 mA, and increasing the beam current through the slits of clamp 1 and clamp 2 to ensure no beam loss on clamp 1 and clamp 2, a maximum beam current of 1 mA can be extracted after injection into the cyclotron.

[0015] Furthermore, the coil current of the magnetic solenoid is adjustable, which is used to adjust the envelope cross-sectional size of the beam at the position of the second clamp. Advantages and effects of the present invention

[0016] 1. Compared with previous solutions, this solution adopts a structure with dual beam clamps arranged on both sides of the magnetic solenoid, which reduces the adjustable beam current intensity from the nA level to below the pA level, meeting the irradiation requirements of aerospace chips in extreme cases and expanding the application range of accelerators; the positioning accuracy of the beam clamp movement is on the order of 0.1mm, which is an order of magnitude lower than the 0.01mm level of the traditional solution, making it easier to implement in engineering.

[0017] 2. Breakthrough Achievement in Extremely Low Beam Current Adjustment, Expanding Application Range: The lower limit of the precisely adjustable extractable beam current of the cyclotron has been significantly reduced from the nA level of existing technologies to the pA level (e.g., below 0.1 pA). This breakthrough meets the extremely demanding beam current requirements of cutting-edge applications such as aerospace chip irradiation, greatly expanding the application scenarios of cyclotrons.

[0018] 3. Significantly Reduced Engineering Implementation Difficulty and Precision Requirements: The motion positioning accuracy requirement of the beam clamp is relaxed from the 0.01 mm level to the 0.1 mm level, a reduction of one order of magnitude, making the design and manufacturing of the mechanical system simpler and more reliable. Adjusting the beam envelope using a magnetic solenoid compensates for the dependence on the absolute positioning accuracy of the beam clamp blocks, thereby reducing the engineering complexity of the beam clamp itself. Avoiding High-Energy Beam Processing Challenges: Beam current adjustment is completed in the low-energy range between the ion source and the accelerator, avoiding beam clamping on the high-energy beam transmission line. This fundamentally eliminates the challenges of strong radiation and shielding caused by high-energy beam losses, as well as the high heat load and complex water cooling requirements of the beam clamp, significantly reducing system operation risks and subsequent maintenance costs.

[0019] 4. Achieve ultra-wide range and continuously adjustable current output: Through the comprehensive control of coarse adjustment of ion source current, precise attenuation of two-stage beam clamps and inherent transmission efficiency of cyclotron, the system can achieve a wide range of beam current adjustment spanning nearly 10 orders of magnitude from 0.1 pA to 1 mA, with extremely high flexibility and adaptability.

[0020] In summary, this invention, through its core design of pre-positioning the adjustment stage, simultaneously achieves three major goals: "performance breakthrough, i.e., reaching the pA level," "engineering simplification, i.e., reducing accuracy and protection requirements," and "safety improvement, i.e., avoiding high-energy beam loss." This provides an efficient, reliable, and easy-to-implement solution for cyclotrons in the field of microbeam precision applications. Attached Figure Description

[0021] Figure 1 A schematic diagram of a beam current adjustment device below the nA level—a beam clamp arranged between the ion source and the accelerator—provided for the purposes of existing technology; Figure 2 This is a schematic diagram of the mechanical structure of a beam clamping device for adjusting beams below the nA level, as given in the prior art. Figure 3 This is a schematic diagram of the high-range adjustment scheme for the beam flux of the cyclotron accelerator according to the present invention. Detailed Implementation Innovation of this invention

[0022] I. Structural Innovation: Achieving Precise Current Limiting at the Front End Using a Combination of "Magnetic Solenoid + Dual Beam Clamps". A magnetic solenoid and two sets of series-connected beam clamps are innovatively integrated between the ion source and the cyclotron. The magnetic solenoid dynamically adjusts the divergence or focusing state of the beam, thereby changing its cross-sectional dimensions; the dual beam clamps attenuate the current intensity through physical obstruction. One core advantage: Avoiding the drawbacks of back-end throttling: By placing the main current intensity regulation stage upstream, the high power loss, strong radiation, and complex cooling problems caused by the high-energy beam being obstructed at the back end of the accelerator are avoided, significantly improving system safety and engineering maintainability. Another core advantage: Overcoming the bottleneck of front-end current limiting accuracy: Through the synergy of "magnetically adjusting beam size" and "dual beam clamp series current reduction", the pressure on current intensity regulation accuracy is distributed from a single mechanical motion precision to multiple adjustable dimensions. This significantly reduces the accuracy requirement for the motion positioning of a single clamping device from the traditional 0.01 mm level to the 0.1 mm level, solving the problem of the dependence of the mechanical system on the limit accuracy of stable control at extremely low flow intensities (such as the pA level).

[0023] II. Performance Breakthrough: Achieving Ultra-Wide Flux Rate Adjustment at the pA Level. Through series attenuation of a two-stage beam clamp (theoretically attenuating by one ten-thousandth per stage), combined with the initial flux of the ion source and acceleration process losses, the system achieves an ultra-wide, continuously adjustable beam output ranging from the mA level to 0.1 pA level. This precise and controllable output capability at extremely low flux rates (nA / pA level) greatly expands the application scenarios of cyclotron accelerators, meeting the needs of fields requiring extremely precise particle flux rate control, such as aerospace electronic device irradiation and precision nuclear medicine research.

[0024] III. Engineering Optimization to Reduce Implementation Difficulty and Cost. Both sets of beam clamps have identical structures, each consisting of four independently moving graphite clamp blocks (top, bottom, left, and right), achieving beam interception by changing the slit area. This design is intuitive, reliable, and easy to manufacture, assemble, and maintain. A balance between accuracy and reliability is achieved: the required motion accuracy is reduced to 0.1 mm, significantly reducing the design and manufacturing difficulty and cost of the mechanical system. Simultaneously, the minimum beam channel size has been optimized (e.g., 0.3 mm × 0.3 mm), reducing interference with beam quality and improving device durability while ensuring ultra-low current intensity control.

[0025] In summary, this invention proposes a novel front-end collaborative control architecture of "magnetic regulation + two-stage mechanical current limiting", which fundamentally resolves the contradiction between "engineering safety" and "control precision" in traditional technologies.

[0026] It achieves precise beam tuning across multiple orders of magnitude (especially at the pA level), breaking through the performance boundaries of existing technologies. Through system design, the ultimate precision requirements of key components have been reduced, making the engineering implementation of high-performance beam tuning systems simpler, more economical, and more reliable. Design principle of the invention

[0027] 1. Dual-insurance front-end beam control: Placing the beam adjustment device between the ion source and the cyclotron avoids safety and maintenance issues caused by high-energy beam loss. A two-stage beam clamp is used in series, allowing each stage to reduce the beam current by an order of magnitude (e.g., 1 / 10000), distributing the overall accuracy requirements and reducing the single-stage positioning accuracy from 0.01 mm to 0.1 mm, significantly reducing manufacturing and control complexity.

[0028] 2. Magnetic solenoid-assisted beam morphology adjustment: A magnetic solenoid is placed between the two-stage beam clamps, and the divergence or focusing of the beam is controlled by adjusting the current. When extremely low current intensity is required, the beam diverges to increase the cross-section, thereby reducing the beam current density per unit area. This assists the beam clamps in achieving fine adjustment and reduces the dependence on the precision of mechanical movement.

[0029] 3. Achieves wide-range adjustment from pA to mA. At low current intensity: the ion source extracts a minimum of 100 μA, which is progressively reduced to the pA level via a two-stage clamping device, ultimately yielding approximately 0.1 pA. At high current intensity: the ion source extracts a maximum of 10 mA, with the clamping device fully open, ultimately yielding approximately 1 mA. Coverage range: 0.1 pA ~ 1 mA, meeting the needs of various application scenarios.

[0030] 4. This invention employs an external ion source; the accelerator's role is to increase beam energy. In principle, beam jamming to reduce the current intensity can be performed during beam injection into or after beam transport from the accelerator. Traditional methods and their disadvantages are as follows: Method 1: Reduce the beam intensity by performing multi-stage beam blocking during beam transmission after the accelerator is feasible. However, because the beam energy is high after acceleration by the accelerator, the high-energy beam needs to be blocked (by using a baffle). The disadvantage is that the radiation dose of the beam transmission line is large (radiation is generated when blocking the beam, and the higher the energy, the greater the radiation). The beam blocker structure is also complex (the beam energy is high when blocking the beam, the beam power hitting the baffle is high, the baffle generates a lot of heat, and water cooling is required).

[0031] Method 2: Beam clamping during beam injection. The injected beam is not accelerated, resulting in low beam energy, thus avoiding the problems of Method 1. However, the current method 1, using only one clamp, cannot achieve ultra-wide-range adjustment, or rather, the clamp positioning accuracy requirement is too high for large-range adjustment. Therefore, my patent proposes our solution, highlighting a wider range of flow intensity adjustment while reducing the requirement for high clamp positioning accuracy.

[0032] In summary, this invention, through front-end arrangement, dual-stage beam clamping, and magnetic field assistance, avoids high-energy beam current problems while reducing the precision requirements from "extreme" to "feasible," achieving wide-range and highly reliable beam current adjustment and improving engineering simplicity and stability.

[0033] Based on the above principles, this invention designs a device for adjusting the beam intensity of a cyclotron accelerator over a wide range. The device consists of a magnetic solenoid arranged between the ion source and the cyclotron accelerator and two sets of beam clamps. The magnetic solenoid is used to adjust the divergence or focusing state of the beam, and the two sets of beam clamps are used to block the beam and reduce the beam intensity. The two sets of beam clamps are arranged on both sides of the magnetic solenoid.

[0034] Furthermore, the two sets of beam clamps have the same structure, each consisting of four movable graphite plates, referred to as the upper beam clamp, lower beam clamp, left beam clamp, and right beam clamp respectively. By adjusting the up-and-down movement of the upper and lower beam clamps and the left-and-right movement of the left and right beam clamps, the square area through which the beam passes through the slit is changed, thereby reducing the beam intensity.

[0035] Furthermore, the motion positioning accuracy requirement for these four card bundle blocks is 0.1 mm.

[0036] Furthermore, the beam is extracted from the ion current, and by adjusting the ion source parameters, the ion source can extract a current intensity of 100 μA to 10 mA.

[0037] Furthermore, the distance between the beam clamp 1 and the ion source outlet is 50cm-100cm. By adjusting the beam current through the slit area of ​​the beam clamp 1, the beam current passing through the beam clamp 1 can be reduced to a maximum of 1 / 10000 of the original.

[0038] Furthermore, the beam current passing through the beam clamp 2 can be reduced to a maximum of 1 / 10000 of its original value.

[0039] Furthermore, by adjusting the ion source to extract a minimum beam current of 100 μA, the minimum beam current after passing through clamp 1 is 100 μA / 10000=10nA, and the minimum beam current after passing through clamp 2 is 10nA / 10000=1pA. Since 90% of the beam current is lost during the injection and acceleration process in the cyclotron, meaning the cyclotron can extract a beam with a current of 1 / 10 of the injection current, when the minimum beam current after passing through clamp 2 is 10nA / 10000=1pA, a minimum beam current of 0.1pA can be extracted after injection into the cyclotron.

[0040] Furthermore, by adjusting the ion source to extract a maximum beam current of 10 mA, and increasing the beam current through the slits of clamp 1 and clamp 2 to ensure no beam loss on clamp 1 and clamp 2, a maximum beam current of 1 mA can be extracted after injection into the cyclotron.

[0041] Furthermore, the coil current of the magnetic solenoid is adjustable, which is used to adjust the envelope cross-sectional size of the beam at the position of the second clamp. Example 1

[0042] The ion source can extract a current intensity of 100 μA to 10 mA. When the beam from the ion source exits to the beam clamp position, the transverse interface size of the beam envelope is 30 mm × 30 mm, assuming that the beam is uniformly distributed in the transverse direction. Adjust the beam current through the slit of clamp 1 to 0.3mm × 0.3mm, and the beam current intensity is (0.3mm × 0.3mm) / (30mm × 30mm) = 1 / 10000 of the original. Adjust the current of the solenoid coil so that the beam current must be dispersed and the cross-sectional area of ​​the beam envelope at clamp 2 is 30mm × 30mm. Adjust the beam current through the slit of clamp 2 to 0.3mm × 0.3mm, and the beam current intensity is (0.3mm × 0.3mm) / (30mm × 30mm) = 1 / 10000 of the original. The beam current through clamp 2 is injected into the cyclotron with a loss of 90%, and a minimum beam current of 0.1pA can be extracted. When the beam current through the slits of clamp 1 and clamp 2 is greater than 30mm × 30mm, and the solenoid is operating in a beam-focusing state, with no beam loss on clamp 1 and clamp 2, the cyclotron can extract a maximum beam current of 1mA. That is, the cyclotron can achieve beam current intensity adjustment over a wide range of 0.1 pA to 1mA.

[0043] In this embodiment, the minimum beam current through the slit of the clamping device is 0.3mm × 0.3mm. The clamping device consists of four clamping blocks: upper, lower, left, and right. The positioning accuracy of the four clamping blocks only needs to reach 0.1mm. The principle is that the current of the magnetic solenoid between the two sets of clamping devices can be adjusted. That is, the cross-sectional size of the beam current envelope through the clamping device 2 can be adjusted by the magnetic solenoid, thereby further finely adjusting the current intensity extracted from the cyclotron without the need for high-precision positioning of the clamping blocks. This will also greatly reduce the engineering complexity of the clamping device manufacturing.

[0044] It should be emphasized that the above specific embodiments are merely explanations of the present invention and are not intended to limit the present invention. After reading this specification, those skilled in the art can make modifications to the above embodiments without contributing any inventive step, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A device for wide-range adjustment of the beam current intensity of a cyclotron accelerator, characterized in that: The device consists of a magnetic solenoid and two sets of beam clamps arranged between the ion source and the cyclotron. The magnetic solenoid is used to adjust the divergence or focusing state of the beam, and the two sets of beam clamps are used to block the beam and reduce the beam intensity. The two sets of beam clamps are arranged on both sides of the magnetic solenoid.

2. The device for wide-range adjustment of cyclotron beam current intensity according to claim 1, characterized in that: The two sets of beam clamps have the same structure, each consisting of four movable graphite plates, referred to as the upper beam clamp, lower beam clamp, left beam clamp, and right beam clamp respectively. By adjusting the up-and-down movement of the upper and lower beam clamps and the left-and-right movement of the left and right beam clamps, the square area through which the beam passes through the slit is changed, thereby reducing the beam intensity.

3. The device for wide-range adjustment of cyclotron beam current intensity according to claim 2, characterized in that: The required motion positioning accuracy for the four clip blocks is 0.1 mm.

4. The device for wide-range adjustment of cyclotron beam current intensity according to claim 1, characterized in that: The beam is drawn from the ion source, and by adjusting the ion source parameters, the ion source can draw out a current intensity of 100 μA to 10 mA.

5. The device for wide-range adjustment of cyclotron beam current intensity according to claim 4, characterized in that: The distance between the beam clamp 1 and the ion source outlet is 50cm-100cm. By adjusting the beam current through the slit area of ​​the beam clamp 1, the beam current passing through the beam clamp 1 can be reduced to a maximum of 1 / 10000 of the original.

6. The device for wide-range adjustment of cyclotron beam current intensity according to claim 1, characterized in that: Increase the current in the solenoid coil to make the beam diverge, and adjust the beam current through the slit area of ​​the beam clamp 2 so that the beam current passing through the beam clamp 2 can be reduced to 1 / 10000 of its original value.

7. The device for wide-range adjustment of cyclotron beam current intensity according to claim 1, characterized in that: Adjust the ion source to extract a minimum beam current of 100 μA. The minimum beam current after passing through clamp 1 is 100 μA / 10000=10nA, and the minimum beam current after passing through clamp 2 is 10nA / 10000=1pA. Since 90% of the beam is lost during injection and acceleration in the cyclotron, the cyclotron can extract a beam with a current of 1 / 10 of the injection current. When the minimum beam current after passing through clamp 2 is 10nA / 10000=1pA, the minimum beam current after injection into the cyclotron can be extracted to be 0.1pA.

8. The device for wide-range adjustment of cyclotron beam current intensity according to claim 7, characterized in that: Adjust the ion source to extract a maximum beam current of 10 mA, increase the beam current through the slits of clamp 1 and clamp 2 to ensure no beam loss on clamp 1 and clamp 2, and after injection into the cyclotron, a maximum beam current of 1 mA can be extracted.

9. The device for wide-range adjustment of cyclotron beam current intensity according to claim 2, characterized in that: The coil current of the magnetic solenoid is adjustable, which is used to adjust the envelope cross-sectional size of the beam at the position of the second bundle clamp.

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