A low-energy heavy ion beam current dynamic focusing device and method

Abstract

The application provides a low-energy heavy ion beam dynamic focusing device and method, and relates to the technical field of beam transmission.The device comprises: a vacuum beam pipeline for confining the transmission of an ion beam inside; at least one composite field generating module located on a beam transmission path, the composite field generating module comprising a plurality of focusing units arranged at intervals along the axial direction of the vacuum beam pipeline, for generating an independently adjustable electrostatic quadrupole field and a dynamic pulsed magnetic field inside the vacuum beam pipeline; and a beam diagnosis feedback control module electrically connected to the composite field generating module, for monitoring the spatial charge distribution, beam envelope size and position information of the ion beam in real time, and generating a control signal according to a preset algorithm to dynamically adjust the strength and distribution of the electrostatic quadrupole field and the dynamic pulsed magnetic field generated by the composite field generating module.The application can significantly improve the disturbance suppression capability and transmission efficiency of the system.

Description

Technical Field

[0001] This invention relates to the field of beam transmission technology, and in particular to a low-energy heavy ion beam dynamic focusing device and method. Background Technology

[0002] Low-energy heavy-ion accelerators play a crucial role in materials modification, biological irradiation, semiconductor ion implantation, and fundamental nuclear physics research. In these applications, the efficient and stable transmission of the beam from the ion source to the target station directly determines the performance of the entire system and the reliability of experimental results. However, due to the slow velocity and large charge of low-energy heavy ions, the Coulomb repulsion within the beam is extremely strong. This space charge effect is the fundamental reason for the beam's lateral divergence, the rapid increase in the beam envelope, and ultimately, the loss of a large number of particles due to impacts with the tube wall.

[0003] To address beam divergence caused by space charge effects, current technologies primarily focus on single-physical-field focusing and static-composite-field focusing. While pure electrostatic quadrupole lenses offer fast response times, their focusing power is relatively limited in the face of strong low-energy space charge forces. Pure magnetic lenses, though providing strong focusing power, are essentially ineffective in the extremely low-energy region below tens of keV, and the establishment and changes in the magnetic field exhibit millisecond-level lag, making it difficult to respond quickly to instantaneous beam fluctuations. Electromagnetic hybrid focusing lenses, developed to combine the advantages of both, often employ static or quasi-static composite field designs, with fixed parameters or only supporting slow switching, making it impossible to sense and respond to dynamic changes in the beam during transmission in real time.

[0004] Although some schemes attempt to introduce dynamic adjustment technology to change ion trajectories, they usually focus on "macro-adjustment" to adapt to different processing sizes. The control model is relatively simple and does not involve precise feedback based on the fusion of multiple parameters such as real-time beam envelope, divergence angle and space charge distribution. It also does not make full use of the synergistic complementary mechanism between the rapid response of the electrostatic field and the strong focusing capability of the magnetic field. Summary of the Invention

[0005] This invention provides a low-energy heavy ion beam dynamic focusing device and method to address the shortcomings of existing technologies that lack the ability to accurately sense beam states such as internal space charge distribution in real time and coordinate the control of composite electromagnetic fields to cope with space charge effects and transient disturbances, thereby achieving long-distance, efficient, stable beam transmission and high-quality maintenance.

[0006] This invention provides a low-energy heavy ion beam dynamic focusing device, comprising: Vacuum beam confinement channel is used to confine the propagation of an ion beam within it; At least one composite field generating module is located on the beam transmission path. The composite field generating module includes multiple focusing units arranged at intervals along the axial direction of the vacuum beam pipe for generating independently adjustable electrostatic quadrupole field and dynamic pulsed magnetic field within the vacuum beam pipe. The beam diagnostic feedback control module is electrically connected to the composite field generation module. It is used to monitor the space charge distribution, beam envelope size and position information of the ion beam in real time, and generate control signals according to a preset algorithm to dynamically adjust the intensity and distribution of the electrostatic quadrupole field and the dynamic pulsed magnetic field generated by the composite field generation module.

[0007] According to the low-energy heavy ion beam dynamic focusing device provided by the present invention, each focusing unit includes an electrostatic quadrupole lens and a solenoid coil or a pair of Helmholtz coils coaxial with it; within the same focusing unit, the electrodes of the electrostatic quadrupole lens and the solenoid coil or the pair of Helmholtz coils are coaxially nested and integrated in physical structure.

[0008] According to the low-energy heavy ion beam dynamic focusing device provided by the present invention, the electrostatic quadrupole lens is composed of four sets of symmetrically distributed cylindrical or curved electrodes, and each electrode is subjected to an independent controllable voltage including a DC bias component and a high-frequency modulation component. The solenoid coil or the pair of Helmholtz coils generates an axisymmetric dynamic pulsed magnetic field in the coil's axial region by receiving a programmed current drive signal from the beam diagnostic feedback control module. The intensity and spatiotemporal distribution of this magnetic field can be independently adjusted.

[0009] According to the low-energy heavy ion beam dynamic focusing device provided by the present invention, the beam diagnostic feedback control module includes: A beam position detector array, distributed at key nodes of the beam transmission path, is used to measure the lateral position and envelope size of the ion beam in real time. A space charge density estimator is used to analyze the fluctuation characteristics of the beam current or fuse data with the beam position detector array to indirectly estimate the space charge distribution inside the ion beam; The central controller has a built-in dynamic focusing algorithm model. The dynamic focusing algorithm model calculates the target values ​​of the electrostatic quadrupole gradient and the dynamic pulse magnetic field strength required to maintain the optimal transmission state by combining the lateral position, the envelope size and the space charge distribution. The digital-to-analog conversion and drive module is used to convert the digital instructions of the central controller into analog signals and amplify them to drive the high-voltage power supply and coil current source in the composite field generation module.

[0010] According to the low-energy heavy ion beam dynamic focusing device provided by the present invention, the operating point voltage of the electrostatic quadrupole lens and the operating point current of the solenoid coil or the pair of Helmholtz coils are preset to a matching coupling relationship by the beam diagnostic feedback control module according to the target ion type and energy, so as to realize the synergistic superposition effect of the electrostatic quadrupole field and the dynamic pulsed magnetic field in space.

[0011] According to the low-energy heavy ion beam dynamic focusing device provided by the present invention, the vacuum beam channel is a high-vacuum stainless steel cavity, and the inner wall of the vacuum beam channel is electropolished and coated to reduce the gas desorption rate and secondary electron emission, and the interior of the vacuum beam channel maintains a density better than 1×10⁻⁶. -4 Vacuum degree in Pa.

[0012] The present invention also provides a method for dynamic focusing of low-energy heavy-ion beams, based on any of the low-energy heavy-ion beam dynamic focusing devices described above, comprising the following steps: S1. Start the beam and continuously collect real-time data on the lateral position, envelope size and space charge intensity of the ion beam through the beam diagnostic feedback control module; S2. The beam diagnostic feedback control module compares the real-time data with the ideal transmission model, calculates the error of the current beam deviating from the optimal state, and calculates a series of adjustment commands for the electrostatic quadrupole gradient and dynamic pulse magnetic field strength required to offset the error and achieve optimal focusing based on the dynamic focusing algorithm. S3. The beam diagnostic feedback control module synchronously and coordinately changes the voltage and current in all the focusing units used to generate the electrostatic quadrupole field and the dynamic pulsed magnetic field according to the adjustment command, thereby establishing a composite electromagnetic field distribution around the ion beam that is precisely matched with the current beam state and dynamically evolves. S4. Repeat steps S1 to S3 to form a closed-loop control circuit, enabling the composite field generation module to track and compensate for disturbances in the ion beam caused by space charge effect, external interference, or load changes in real time, ensuring that the ion beam remains stable throughout the transmission process.

[0013] According to the low-energy heavy ion beam dynamic focusing method provided by the present invention, in step S2, the dynamic focusing algorithm is specifically as follows: A beam envelope equation containing a space charge force term is established as the core model. The transverse position and envelope size of the ion beam measured in real time are used as boundary conditions to input the beam envelope equation. The focusing intensity required to maintain the stability of the beam envelope is solved in reverse. The focusing intensity is then decomposed into independent control components of the electrostatic quadrupole field and the dynamic pulsed magnetic field.

[0014] According to the low-energy heavy ion beam dynamic focusing method provided by the present invention, each focusing unit in the composite field generation module includes an electrostatic quadrupole lens and a solenoid coil or a pair of Helmholtz coils; in step S3, changing the voltage and current in all the focusing units used to generate the electrostatic quadrupole field and the dynamic pulsed magnetic field includes: The voltage of the electrostatic quadrupole lens and the current of the solenoid coil or the pair of Helmholtz coils are adjusted. The voltage adjustment of the electrostatic quadrupole lens specifically includes slow adjustment of a basic DC voltage component and rapid adjustment of the amplitude and phase of a high-frequency AC modulation voltage. The regulation of the current in the solenoid coil or the pair of Helmholtz coils specifically includes slow regulation of a DC current component that generates an axial focusing gradient field and rapid regulation of the amplitude and frequency of an AC oscillating current used to correct lateral deviation.

[0015] According to the low-energy heavy ion beam dynamic focusing method provided by the present invention, after step S4, it further includes: S5. Perform pre-calibration and model update offline, specifically including: During routine maintenance of the device, a calibration beam with known energy, current intensity, and emittance is injected. The preset combinations of voltage and current in the composite field generation module are actively scanned, and the corresponding beam position, envelope and divergence angle response are recorded by the beam diagnostic feedback control module. Based on the recorded response data, the actual optical parameters of the vacuum beam channel are inverted using an inverse optimization algorithm; The actual optical parameters obtained from the inversion are updated in the ideal transmission model and the dynamic focusing algorithm to correct model deviations.

[0016] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement any of the low-energy heavy ion beam dynamic focusing methods described above.

[0017] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the low-energy heavy ion beam dynamic focusing method as described above.

[0018] The present invention also provides a computer program product, including a computer program that, when executed by a processor, implements the low-energy heavy ion beam dynamic focusing method as described above.

[0019] This invention provides a low-energy heavy ion beam dynamic focusing device and method. It constrains the ion beam's propagation within a vacuum beam pipe and places at least one composite field generation module along its propagation path. Multiple focusing units spaced axially within this module generate independently adjustable electrostatic quadrupole fields and dynamic pulsed magnetic fields, thus providing a dual physical field basis for beam focusing. More importantly, this invention innovatively introduces a beam diagnostic feedback control module electrically connected to the composite field generation module. This module monitors the ion beam's space charge distribution, beam envelope size, and position information in real time, and then generates control signals based on a preset algorithm to dynamically adjust the intensity and distribution of the electrostatic quadrupole field and dynamic pulsed magnetic field in a real-time closed-loop manner. Through the synergistic effect of the above features, this device establishes a closed-loop control architecture that integrates real-time sensing and collaborative execution. It can not only acquire core state data reflecting the evolution of space charge effect in real time and accurately, but also actively and precisely regulate the electrostatic quadrupole field and dynamic pulsed magnetic field through spatiotemporal decoupling. This effectively counteracts the strong Coulomb repulsion force of low-energy heavy ions, suppresses the beam lateral divergence and rapid envelope growth caused by various complex transient disturbances, greatly reduces the loss caused by particle impact on the tube wall, and ultimately achieves a comprehensive improvement in transmission efficiency and beam quality. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of the low-energy heavy ion beam dynamic focusing device provided by the present invention.

[0022] Figure 2 This is a schematic flowchart of the low-energy heavy ion beam dynamic focusing method provided by the present invention.

[0023] Figure 3 This is a schematic diagram of the structure of the electronic device provided by the present invention.

[0024] Figure label: 1: Vacuum beam channel; 2: Composite field generation module; 21: Focusing unit; 3: Beam diagnostic feedback control module; 31: Beam position detector array; 32: Space charge density estimator; 33: Central controller; 34: Digital-to-analog conversion and drive module. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0026] The embodiments of this application involve at least one, including one or more; where "multiple" means two or more. Furthermore, it should be understood that in the description of this specification, terms such as "first" and "second" are used only for descriptive purposes and should not be construed as indicating relative importance or order. For example, "first device" and "second device" do not represent the degree of importance of the two or their order, but are merely for descriptive distinction. In the embodiments of this application, "and / or" merely describes an association relationship, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0027] The directional terms mentioned in the embodiments of this application, such as "up", "down", "left", "right", "inner", and "outer", are only for reference to the directions in the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of this application, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0028] References to "one embodiment," "in some examples," or "some embodiments" as described in this specification mean that one or more embodiments of this specification include a particular feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in some examples," "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0029] In low-energy heavy-ion accelerator systems, the efficiency and stability of the ion beam transmission from the ion source to the target directly determines the overall system performance. Due to the slow velocity and large charge of low-energy heavy ions, they are highly susceptible to strong space charge effects, leading to lateral beam divergence. While existing technologies have developed electrostatic focusing, pure magnetic focusing, and static composite field focusing techniques, they often face challenges such as insufficient electrostatic focusing force, magnetic focusing failure in the low-energy region, or the inability of static designs to respond in real-time to high-frequency transient fluctuations such as ion source state fluctuations and external electromagnetic interference.

[0030] To completely solve the control lag and model failure problems exhibited by existing technologies when dealing with complex dynamic disturbances, this application provides a low-energy heavy ion beam dynamic focusing device and method. This device deploys a composite field generation module with a coaxial nested structure within a vacuum beam channel, utilizes a beam diagnostic feedback control module with deep hardware and software integration to sense the space charge distribution and envelope state of the beam in real time, and combines a built-in envelope equation to precisely decouple the focusing control command into dual-mode independent control signals, thereby constructing a millisecond-level electrostatic and magnetic field spatiotemporal coordinated closed-loop control system.

[0031] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0032] First, combine Figure 1 The low-energy heavy ion beam dynamic focusing device provided in the embodiments of the present invention will be described in detail.

[0033] like Figure 1 As shown, this embodiment provides a low-energy heavy ion beam dynamic focusing device, specifically including: a vacuum beam pipe 1, at least one composite field generation module 2, and a beam diagnostic feedback control module 3. The vacuum beam pipe 1 is used to confine the ion beam for propagation within it. The composite field generation module 2 is located on the beam propagation path and includes multiple focusing units 21 spaced along the axial direction of the vacuum beam pipe 1, used to generate independently adjustable electrostatic quadrupole fields and dynamic pulsed magnetic fields within the vacuum beam pipe 1. The beam diagnostic feedback control module 3 is electrically connected to the composite field generation module 2, used to monitor the space charge distribution, beam envelope size, and position information of the ion beam in real time, and to generate control signals according to a preset algorithm to dynamically adjust the intensity and distribution of the electrostatic quadrupole field and dynamic pulsed magnetic field generated by the composite field generation module 2. Figure 1 The electrical connection between the mid-beam diagnostic feedback control module 3 and the composite field generation module 2 is shown by arrows.

[0034] Specifically, such as Figure 1 As shown, each focusing unit 21 includes an electrostatic quadrupole lens and a solenoid coil or a pair of Helmholtz coils coaxial with it. Within the same focusing unit 21, the electrodes of the electrostatic quadrupole lens and the solenoid coil or the pair of Helmholtz coils are coaxially nested and integrated in physical structure. This coaxial nesting structure makes the electrostatic field and magnetic field highly coincident in space, which can produce a synergistic focusing effect on the beam.

[0035] Furthermore, the electrostatic quadrupole lens consists of four sets of symmetrically distributed cylindrical or curved electrodes, each of which is subjected to an independently controllable voltage containing a DC bias component and a high-frequency modulation component. A solenoid coil or a pair of Helmholtz coils, by receiving a programmed current drive signal from the beam current diagnostic feedback control module 3, generates an axisymmetric, dynamically pulsed magnetic field in the coil's axial region, with independently adjustable intensity and spatiotemporal distribution. Specifically, such as... Figure 1 The control signal is output from the central controller 33 via the digital-to-analog converter and drive module 34 to the composite field generation module 2. Independent voltages are applied to the four sets of electrodes of the electrostatic quadrupole lens. Each voltage includes a basic DC bias for providing macroscopic focusing force and a high-frequency modulation component for rapid response to disturbances. A solenoid coil or Helmholtz coil receives a programmed current drive signal from the beam diagnostic feedback control module 3. This signal determines the magnetic field strength, spatiotemporal distribution, and pulse characteristics. A linear restoring force proportional to the radial position is provided by the electrostatic quadrupole field, achieving lateral focusing. A strong focusing force is provided by the dynamic pulsed magnetic field, compensating for the limitations of electrostatic focusing in low-energy or high-current regions. Finally, by independently adjusting the parameters of the electrostatic and magnetic fields, the focusing intensity can be rapidly adjusted for different beam states, effectively suppressing beam divergence caused by space charge effects.

[0036] Preferably, the electrode surface of the electrostatic quadrupole lens is coated with a secondary electron emission suppression coating (e.g., a carbon film or a special metal oxide coating). This coating effectively suppresses secondary electron emission generated by high-energy electrons bombarding the electrode surface, thereby reducing background noise, improving the accuracy of beam diagnostics, and reducing beam quality degradation. Furthermore, since solenoid coils or Helmholtz coils generate Joule heat during long-term operation at high currents, the coils are wound with hollow wires and equipped with a water-cooling circulation system to ensure thermal stability and magnetic field uniformity. Cooling water flows through the hollow wires, carrying away heat and enabling the coils to withstand continuous high-power operation.

[0037] like Figure 1 As shown, the beam diagnostic feedback control module 3 includes: a beam position detector array 31, a space charge density estimator 32, a central controller 33, and a digital-to-analog conversion and drive module 34. Among them, Figure 1The diagram shows multiple detectors arranged along the pipeline. A beam position detector array 31 is distributed at key nodes in the beam transmission path to measure the lateral position and envelope size of the ion beam in real time. A space charge density estimator 32 is used to analyze the fluctuation characteristics of the beam current or fuse data with that of the beam position detector array 31 to indirectly estimate the space charge distribution within the ion beam. A central controller 33 incorporates a dynamic focusing algorithm model, which calculates the target values ​​of the electrostatic quadrupole gradient and dynamic pulsed magnetic field strength required to maintain optimal transmission by integrating the lateral position, envelope size, and space charge distribution. A digital-to-analog conversion and drive module 34 converts the digital instructions of the central controller 33 into analog signals and amplifies them to drive the high-voltage power supply and coil current source in the composite field generation module 2.

[0038] The beam position detector array provides geometric state information of the beam; the space charge density estimator provides the intensity distribution of the Coulomb repulsion force inside the beam; the central controller, as the decision core, calculates the optimal focusing field configuration by fusing multiple parameters; and the digital-to-analog conversion and drive module, as the execution link, converts digital commands into actual voltage and current, thus forming a complete closed loop of perception-decision-execution, enabling the system to respond to changes in beam state in real time and automatically maintain optimal focusing.

[0039] In addition, such as Figure 1 As shown, the device in this embodiment also includes the following preferred features. Based on the target ion type and energy, the operating point voltage of the electrostatic quadrupole lens and the operating point current of the solenoid coil or a pair of Helmholtz coils are preset to a matched coupling relationship by the beam current diagnostic feedback control module 3, so as to achieve a synergistic superposition effect of the electrostatic quadrupole field and the dynamic pulsed magnetic field in space.

[0040] Specifically, during system initialization or ion type switching, the central controller 33 calculates the initial voltage and current values ​​that match the current ion energy and flux intensity according to a preset lookup table or model, and outputs them to the driving power supply of the electrostatic quadrupole lens and the coil, respectively, to ensure that the electrostatic field and magnetic field cooperate with each other in space, rather than canceling each other or producing adverse coupling, thereby improving focusing efficiency, reducing adjustment time, and enabling the device to quickly adapt to the needs of different ion types and energies.

[0041] like Figure 1 As shown, vacuum beam pipe 1 is a high-vacuum stainless steel cavity. Figure 1 The inner wall of the central tube is schematically a smooth surface. Its inner wall undergoes electropolishing and plating treatment to reduce gas desorption rate and secondary electron emission. Furthermore, the internal temperature of the vacuum beam tube 1 maintains a level better than 1×10⁻⁶. -4The vacuum level is measured in Pa. Furthermore, multiple standard flange interfaces can be installed on the vacuum beam pipe 1 for mounting the probes of the composite field generation module 2 and the beam diagnostic feedback control module 3, as well as the vacuum measurement gauge and pumping device, facilitating modular assembly and maintenance. This high-vacuum environment reduces collisions between the ion beam and residual gas molecules, lowers beam scattering and energy loss, and provides a clean path for long-distance transmission.

[0042] The low-energy heavy ion beam dynamic focusing device provided in this embodiment, through the coordinated operation of the vacuum beam pipe 1, the composite field generation module 2, and the beam diagnostic feedback control module 3, constructs a hardware foundation capable of sensing the beam state in real time and dynamically adjusting the electrostatic quadrupole field and the dynamic pulsed magnetic field.

[0043] The following is combined with Figure 2 The low-energy heavy ion beam dynamic focusing method provided in the embodiments of the present invention will be described in detail.

[0044] Figure 2 The flowchart shows the low-energy heavy ion beam dynamic focusing method provided by the present invention. S1 to S4 represent the core steps, and S5, an optional offline pre-calibration step, is included.

[0045] This embodiment provides a low-energy heavy ion beam dynamic focusing method, which is implemented based on the low-energy heavy ion beam dynamic focusing device described in the above embodiment. Figure 2 As shown, the method includes the following steps: Step S1: Start the beam and continuously collect real-time data on the lateral position, envelope size, and space charge intensity of the ion beam through the beam diagnostic feedback control module.

[0046] Specifically, after being extracted from the ion source, the beam propagates along the vacuum beam pipe 1. The beam position detector array 31 measures the lateral position of the beam in real time. , and envelope size , ,in, , These are the two directions perpendicular to the transverse (cross-section) of the beam. For the direction of beam transmission (beam axis), The time parameter is used; the space charge density estimator 32 indirectly estimates the space charge density by analyzing the fluctuation characteristics of the beam current or fusing it with position detector data. And the corresponding space charge force intensity. These data are transmitted to the central controller 33 in real time.

[0047] By acquiring the current state of the beam, it serves as the basis for subsequent dynamic focusing adjustments. In particular, the real-time data on the space charge force intensity is dynamic disturbance information that cannot be obtained in existing static schemes. It provides high-frequency, multi-dimensional input parameters for closed-loop control, enabling the system to sense the instantaneous changes in the space charge effect.

[0048] Step S2: The beam diagnostic feedback control module compares the real-time data with the ideal transmission model, calculates the error of the current beam deviating from the optimal state, and calculates a series of adjustment commands for the electrostatic quadrupole gradient and dynamic pulse magnetic field strength required to offset the error and achieve optimal focusing based on the dynamic focusing algorithm.

[0049] Specifically, the central controller 33 receives real-time data from step S1 and compares it point-by-point with the internally stored ideal transmission model (such as the beam envelope evolution curve under conditions of no space charge effect or emittance matching) to obtain the error vector of the current beam deviating from the optimal state. Then, the central controller 33 executes a dynamic focusing algorithm and, based on the dynamic focusing algorithm, calculates a series of adjustment commands for the electrostatic field gradient and magnetic field strength required to offset this error and achieve optimal focusing. Specifically, the dynamic focusing algorithm includes: establishing a beam envelope equation containing a space charge force term as the core model, inputting the real-time measured beam radius and position as boundary conditions into the equation, solving in reverse to obtain the focusing intensity required to maintain the stability of the beam envelope, and decomposing the focusing intensity into independent control components for the electrostatic quadrupole field and the dynamic pulsed magnetic field. This embodiment solves the problem of how to deduce the control quantity from the beam state by transforming the abstract requirement for maintaining stable focusing into specific field parameters, such as the electrostatic quadrupole field gradient and the dynamic pulsed magnetic field strength. Compared with traditional PID control or fixed models, this algorithm can accurately compensate for the nonlinear effects of the space charge effect, and is especially suitable for low-energy heavy ion strong space charge scenarios.

[0050] More specifically, the core algorithm model is based on the beam envelope equation (an extended form of the KV envelope model) that includes a space charge force term: (1); (2), in, , The beam is respectively in , The radius of the envelope (half-width) of the direction. , The total focusing intensity function is derived from the electrostatic quadrupole gradient. With magnetic field focusing intensity synthesis: (3), (4), The electrostatic field of the quadrupole , Direction provides focusing with opposite signs; a uniform axial magnetic field provides focusing with the same signs, where... , Geometric reactivity, obtained from diagnostic data. , This is a space charge repulsion term, related to the space charge density. Proportional: (5); (6), in, For local beam current, denoted as ionic axial velocity.

[0051] Solution process: Real-time measurements , , Substitute these boundary conditions into the envelope equation; then solve in reverse order for the required solution. , The distribution causes the envelope evolution to converge to the beam at... x, y Target stable radius in the direction , The total focused intensity is decomposed into electrostatic field gradients. With magnetic field strength The independent control components are further converted into electrode voltages. With coil current The set value.

[0052] S3: The beam diagnostic feedback control module synchronously and coordinately changes the voltage and current used to generate the electrostatic quadrupole field and dynamic pulsed magnetic field in all focusing units according to the adjustment command, thereby establishing a composite electromagnetic field distribution around the ion beam that is precisely matched to the current beam state and dynamically evolves.

[0053] Specifically, the digital-to-analog converter and drive module 34 converts the digital instructions output by the central controller 33 into analog voltage and current signals, which drive the high-voltage power supply of the electrostatic quadrupole lens and the current source of the solenoid coil (or Helmholtz coil), respectively. Voltage regulation of the electrostatic quadrupole lens includes slow regulation of a fundamental DC voltage component and rapid regulation of the amplitude and phase of a high-frequency AC modulated voltage; current regulation of the solenoid coil or a pair of Helmholtz coils includes slow regulation of a DC current component that generates an axial focusing gradient field and rapid regulation of the amplitude and frequency of an AC oscillating current used to correct lateral deviation.

[0054] It is worth noting that high-frequency disturbances are caused by instantaneous fluctuations in space charge, while low-frequency lateral deviations are caused by mechanical or magnetic field instabilities. The DC component provides macroscopic focusing force to maintain the basic envelope of the beam. The high-frequency modulation component and the AC oscillation current are used to suppress disturbances at different time scales. The rapid response of the electrostatic field (microsecond level) and the strong focusing capability of the magnetic field (millisecond-level adjustment) complement each other in space and time. When the beam load changes abruptly (e.g., from 5mA to 20mA), the high-frequency modulation mode can quickly compensate for drastic changes in space charge force at 50kHz, while the AC oscillation current corrects the lateral deviation at 500Hz, reducing the beam lateral position jitter amplitude to ±30μm and maintaining the divergence angle at ≤0.5mrad, thus avoiding beam wall collision losses.

[0055] In detail, the digital-to-analog conversion and drive module 34 synchronously and coordinately changes the electrode voltage of the electrostatic quadrupole lens and the current of the solenoid coil in all focusing units 21 according to the adjustment command, thereby establishing a dynamically evolving composite electromagnetic field distribution around the beam that precisely matches the current beam state.

[0056] Adjustment strategy: Electrostatic quadrupole lens voltage adjustment, specifically: (7), in, This is the voltage adjustment function for the electrostatic quadrupole lens. Basic DC bias (slow adjustment, used for macroscopic focusing force matching). It is a high-frequency modulation component (fast response, suppressing high-frequency disturbances). For high-frequency adjustment, amplitude With phase It is calculated in real time by a feedback algorithm.

[0057] Solenoid / Helmholtz coil current adjustment: (8), in, This is the current regulation function for the solenoid / Helmholtz coil. To generate the DC component of the axially focused gradient field (slow adjustment); To correct the alternating current of lateral deviation, The frequency and amplitude of the alternating oscillating current. With frequency Determined based on the error signal.

[0058] S4: Repeat steps S1 to S3 to form a closed-loop control circuit, enabling the composite field generation module to track and compensate for disturbances in the ion beam caused by space charge effect, external interference or load changes in real time, and ensuring that the ion beam remains stable throughout the transmission process.

[0059] Specifically, S1-S3 are executed cyclically with a set sampling period (e.g., 0.5ms). Within each cycle, the central controller 33 utilizes an FPGA (Field-Programmable Gate Array) for high-speed computation, performing numerical integration and inverse solving of the envelope equation, and updating the output voltage and current commands. The closed-loop control loop continues to operate until the beam transmission ends. Through high-speed iteration, the response speed of the control system exceeds the rate of change of the disturbance, achieving real-time tracking and active compensation.

[0060] This embodiment forms a high-speed closed-loop control circuit by repeating steps S1 to S3, enabling the device to track and compensate for any disturbances in the beam caused by space charge effect, external interference, or load changes in real time. This ensures that the beam maintains a stable state with high density and small divergence angle throughout the entire transmission process, ultimately achieving high-efficiency and high-quality transmission.

[0061] Optional step S5: Following step S4, offline pre-calibration and model update are also performed. Specifically: During routine maintenance of the device, such as automatically entering offline pre-calibration mode every 24 hours, a calibration beam with known energy, current intensity, and emittance is injected.

[0062] The preset combination of voltage and current in the active scanning composite field generation module (i.e., the scanning matrix of voltage and coil current of the electrostatic quadrupole lens) is used, while the corresponding beam position, envelope and divergence angle response are recorded by the beam diagnostic feedback control module.

[0063] Based on the recorded response data, the actual optical parameters of the vacuum beam channel, including the equivalent field gradient, aberration coefficients, and drift length of each focusing unit, are derived through inverse optimization algorithms such as least squares or genetic algorithms.

[0064] The actual parameters obtained from the inversion are updated into the ideal transport model and the dynamic focusing algorithm to correct model biases.

[0065] Specifically, the central controller 33 executes a calibration procedure, sequentially changing the voltage and coil current of the electrostatic quadrupole lens, and reading the outputs of the beam position detector array 31 and the space charge density estimator 32 under each combination. Then, an inverse optimization algorithm is used to fit the set of optical parameters that best matches the measured response. Finally, these parameters are written to the model storage area, replacing the original theoretical or old values.

[0066] By compensating for changes in actual optical parameters caused by electrode contamination, coil aging, and vacuum drift during long-term equipment operation, the consistency between the model and the physical system is ensured. Long-term stability of closed-loop control is maintained, eliminating the need for frequent manual calibration; for industrial applications such as ion implantation and material modification, this significantly reduces equipment downtime for maintenance.

[0067] In some possible embodiments of the present invention, the sampling and control cycle of the closed-loop control loop is 0.5ms. The central controller 33 uses an FPGA to implement high-speed computation, which can complete the numerical integration and inverse solution of the envelope equations (1)-(6) in each cycle. For a typical 80keV argon ion beam (the charge of the ion beam...) mass number ), axial velocity When the peak beam current Initial envelope radius At that time, space charge repulsion term Reachable At this point, the electrostatic field gradient output by the algorithm Approximately magnetic field focusing intensity Approximately DC bias voltage of corresponding electrode Solenoid DC current This parameter combination effectively suppressed beam envelope growth over a 1m transmission distance, significantly improved beam transmission efficiency, and achieved stable transmission of high-quality beams.

[0068] To address the drastic changes in space charge force caused by sudden beam load changes (e.g., a jump from 5 mA to 20 mA), the control strategy activates the high-frequency modulation mode of equations (7)-(8): the electrostatic quadrupole lens. Frequency Amplitude The sine wave is used for rapid disturbance suppression; the solenoid coil's Frequency Amplitude The alternating current swing is used to correct envelope asymmetry caused by instantaneous lateral offset. Under sudden load, this dual-band coordinated regulation can reduce the beam lateral position jitter amplitude to ±30μm, while maintaining the divergence angle. 0.5 mrad to avoid beam wall collision loss caused by excessive local space charge. The system automatically enters offline pre-calibration mode every 24 hours, and performs parameter inversion and model update according to equations (1)-(6) to ensure long-term stability and accuracy.

[0069] By solving the focusing requirements in real time using the envelope equation containing the space charge term, the fast-response electrostatic field and the strong but slow magnetic field are allocated in a coordinated manner according to time and space. Furthermore, high-frequency / low-frequency dual-mode modulation is used to suppress disturbances at different time scales. Combined with periodic model calibration, this achieves high stability and high transmission efficiency of low-energy heavy ion beams over long distances.

[0070] The low-energy heavy ion beam dynamic focusing device and method provided by this invention achieves the following beneficial effects by constructing a composite dynamic focusing architecture of an electrostatic quadrupole field + a dynamic pulsed magnetic field and introducing a closed-loop control algorithm based on multi-parameter real-time feedback: Significantly improves transmission efficiency: Real-time compensation for beam divergence caused by space charge effect effectively reduces beam wall impact loss, significantly improving beam transmission efficiency under typical operating conditions.

[0071] Improve beam quality: Dynamically adjust the distribution and intensity of the composite field, actively suppress emissivity growth, correct beam deflection angle and position, and obtain a smaller, more uniform and more stable terminal beam spot.

[0072] Strong adaptability: The control system based on real-time monitoring and algorithm calculation can automatically adapt to changes in ion type, energy, and flux intensity, as well as parameter drift caused by long-term operation of the equipment.

[0073] High stability and reliability: Through offline pre-calibration and model update mechanisms (e.g., automatic calibration every 24 hours), control accuracy is ensured during long-term operation, reducing manual intervention.

[0074] Figure 3 An example is a schematic diagram of the physical structure of an electronic device, such as... Figure 3As shown, the electronic device may include: a processor 310, a communication interface 320, a memory 330, and a communication bus 340. The processor 310, communication interface 320, and memory 330 communicate with each other via the communication bus 340. The processor 310 can call logic instructions in the memory 330 to execute a low-energy heavy ion beam dynamic focusing method. This method includes: S1, starting the beam and continuously acquiring real-time data on the lateral position, envelope size, and space charge force intensity of the ion beam through the beam diagnostic feedback control module; S2, the beam diagnostic feedback control module compares the real-time data with an ideal transmission model, calculates the error of the current beam deviating from the optimal state, and calculates, based on the dynamic focusing algorithm, a series of adjustments to the electrostatic quadrupole gradient and dynamic pulsed magnetic field intensity required to offset the error and achieve optimal focusing. Instruction S3: The beam diagnostic feedback control module, according to the adjustment instruction, synchronously and coordinately changes the voltage and current in all the focusing units used to generate the electrostatic quadrupole field and the dynamic pulsed magnetic field, thereby establishing a composite electromagnetic field distribution around the ion beam that precisely matches the current beam state and dynamically evolves; S4: Repeat steps S1 to S3 to form a closed-loop control circuit, enabling the composite field generation module to track and compensate for disturbances in the ion beam caused by space charge effect, external interference, or load changes in real time, ensuring that the ion beam remains stable throughout the transmission process.

[0075] Furthermore, the logical instructions in the aforementioned memory 330 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, essentially, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0076] On the other hand, the present invention also provides a computer program product, which includes a computer program that can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the low-energy heavy ion beam dynamic focusing method provided by the above methods. The method includes: S1, starting the beam and continuously collecting real-time data of the lateral position, envelope size, and space charge intensity of the ion beam through the beam diagnostic feedback control module; S2, the beam diagnostic feedback control module compares the real-time data with the ideal transmission model, calculates the error of the current beam deviating from the optimal state, and calculates the amount of data to offset the error based on the dynamic focusing algorithm. S1) The beam diagnostic feedback control module adjusts the voltage and current used to generate the electrostatic quadrupole field and the dynamic pulsed magnetic field in all the focusing units according to the adjustment instructions, thereby establishing a composite electromagnetic field distribution around the ion beam that is precisely matched with the current beam state and dynamically evolves; S2) Steps S1 to S3 are repeated to form a closed-loop control loop, enabling the composite field generation module to track and compensate for disturbances in the ion beam caused by space charge effect, external interference or load changes in real time, ensuring that the ion beam remains stable throughout the transmission process.

[0077] In another aspect, the present invention also provides a non-transitory computer-readable storage medium storing a computer program thereon. When executed by a processor, the computer program implements the low-energy heavy ion beam dynamic focusing method provided by the methods described above. The method includes: S1, starting the beam and continuously acquiring real-time data of the lateral position, envelope size, and space charge intensity of the ion beam through the beam diagnostic feedback control module; S2, the beam diagnostic feedback control module compares the real-time data with an ideal transmission model, calculates the error of the current beam deviating from the optimal state, and calculates a series of steps required to offset the error and achieve optimal focusing based on the dynamic focusing algorithm. S3. The beam diagnostic feedback control module, according to the adjustment command, synchronously and coordinately changes the voltage and current in all the focusing units used to generate the electrostatic quadrupole field and the dynamic pulsed magnetic field, thereby establishing a composite electromagnetic field distribution around the ion beam that precisely matches the current beam state and evolves dynamically; S4. Repeat steps S1 to S3 to form a closed-loop control circuit, enabling the composite field generation module to track and compensate for disturbances in the ion beam caused by space charge effect, external interference, or load changes in real time, ensuring that the ion beam remains stable throughout the transmission process.

[0078] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0079] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low-energy heavy ion beam dynamic focusing device, characterized in that, include: Vacuum beam confinement channel is used to confine the propagation of an ion beam within it; At least one composite field generating module is located on the beam transmission path. The composite field generating module includes multiple focusing units arranged at intervals along the axial direction of the vacuum beam pipe for generating independently adjustable electrostatic quadrupole field and dynamic pulsed magnetic field within the vacuum beam pipe. The beam diagnostic feedback control module is electrically connected to the composite field generation module. It is used to monitor the space charge distribution, beam envelope size and position information of the ion beam in real time, and generate control signals according to a preset algorithm to dynamically adjust the intensity and distribution of the electrostatic quadrupole field and the dynamic pulsed magnetic field generated by the composite field generation module.

2. The low-energy heavy ion beam dynamic focusing device according to claim 1, characterized in that, Each of the focusing units includes an electrostatic quadrupole lens and a solenoid coil or a pair of Helmholtz coils coaxial with it; within the same focusing unit, the electrodes of the electrostatic quadrupole lens and the solenoid coil or the pair of Helmholtz coils are physically integrated coaxially.

3. The low-energy heavy ion beam dynamic focusing device according to claim 2, characterized in that, The electrostatic quadrupole lens is composed of four sets of symmetrically distributed cylindrical or curved electrodes, each electrode being subjected to an independent controllable voltage containing a DC bias component and a high-frequency modulation component. The solenoid coil or the pair of Helmholtz coils generates an axisymmetric dynamic pulsed magnetic field in the coil's axial region by receiving a programmed current drive signal from the beam diagnostic feedback control module. The intensity and spatiotemporal distribution of this magnetic field can be independently adjusted.

4. The low-energy heavy ion beam dynamic focusing device according to claim 1, characterized in that, The beam diagnostic feedback control module includes: A beam position detector array, distributed at key nodes of the beam transmission path, is used to measure the lateral position and envelope size of the ion beam in real time. A space charge density estimator is used to analyze the fluctuation characteristics of the beam current or fuse data with the beam position detector array to indirectly estimate the space charge distribution inside the ion beam; The central controller has a built-in dynamic focusing algorithm model. The dynamic focusing algorithm model calculates the target values ​​of the electrostatic quadrupole gradient and the dynamic pulse magnetic field strength required to maintain the optimal transmission state by combining the lateral position, the envelope size and the space charge distribution. The digital-to-analog conversion and drive module is used to convert the digital instructions of the central controller into analog signals and amplify them to drive the high-voltage power supply and coil current source in the composite field generation module.

5. The low-energy heavy ion beam dynamic focusing device according to claim 2, characterized in that, The operating point voltage of the electrostatic quadrupole lens and the operating point current of the solenoid coil or the pair of Helmholtz coils are preset to a matching coupling relationship by the beam diagnostic feedback control module according to the target ion type and energy, so as to realize the synergistic superposition effect of the electrostatic quadrupole field and the dynamic pulsed magnetic field in space.

6. The low-energy heavy ion beam dynamic focusing device according to claim 1, characterized in that, The vacuum beam pipe is a high-vacuum stainless steel cavity. The inner wall of the vacuum beam pipe is electropolished and coated to reduce gas desorption rate and secondary electron emission. Furthermore, the internal temperature of the vacuum beam pipe maintains a level better than 1×10⁻⁶. -4 Vacuum degree in Pa.

7. A method for dynamic focusing of a low-energy heavy ion beam, characterized in that, The method based on the low-energy heavy ion beam dynamic focusing device according to any one of claims 1 to 6 includes the following steps: S1. Start the beam and continuously collect real-time data on the lateral position, envelope size and space charge intensity of the ion beam through the beam diagnostic feedback control module; S2. The beam diagnostic feedback control module compares the real-time data with the ideal transmission model, calculates the error of the current beam deviating from the optimal state, and calculates a series of adjustment commands for the electrostatic quadrupole gradient and dynamic pulse magnetic field strength required to offset the error and achieve optimal focusing based on the dynamic focusing algorithm. S3. The beam diagnostic feedback control module synchronously and coordinately changes the voltage and current in all the focusing units used to generate the electrostatic quadrupole field and the dynamic pulsed magnetic field according to the adjustment command, thereby establishing a composite electromagnetic field distribution around the ion beam that is precisely matched with the current beam state and dynamically evolves. S4. Repeat steps S1 to S3 to form a closed-loop control circuit, enabling the composite field generation module to track and compensate for disturbances in the ion beam caused by space charge effect, external interference, or load changes in real time, ensuring that the ion beam remains stable throughout the transmission process.

8. The low-energy heavy ion beam dynamic focusing method according to claim 7, characterized in that, In step S2, the dynamic focusing algorithm is specifically as follows: A beam envelope equation containing a space charge force term is established as the core model. The transverse position and envelope size of the ion beam measured in real time are used as boundary conditions to input the beam envelope equation. The focusing intensity required to maintain the stability of the beam envelope is solved in reverse. The focusing intensity is then decomposed into independent control components of the electrostatic quadrupole field and the dynamic pulsed magnetic field.

9. The low-energy heavy ion beam dynamic focusing method according to claim 7, characterized in that, Each focusing unit in the composite field generation module includes an electrostatic quadrupole lens and a solenoid coil or a pair of Helmholtz coils. In step S3, changing the voltage and current in all the focusing units used to generate the electrostatic quadrupole field and the dynamic pulsed magnetic field includes: The voltage of the electrostatic quadrupole lens and the current of the solenoid coil or the pair of Helmholtz coils are adjusted. The voltage adjustment of the electrostatic quadrupole lens specifically includes slow adjustment of a basic DC voltage component and rapid adjustment of the amplitude and phase of a high-frequency AC modulation voltage. The regulation of the current in the solenoid coil or the pair of Helmholtz coils specifically includes slow regulation of a DC current component that generates an axial focusing gradient field and rapid regulation of the amplitude and frequency of an AC oscillating current used to correct lateral deviation.

10. The low-energy heavy ion beam dynamic focusing method according to claim 7, characterized in that, Following step S4, the following is also included: S5. Perform pre-calibration and model update offline, specifically including: During routine maintenance of the device, a calibration beam with known energy, current intensity, and emittance is injected. The preset combinations of voltage and current in the composite field generation module are actively scanned, and the corresponding beam position, envelope and divergence angle response are recorded by the beam diagnostic feedback control module. Based on the recorded response data, the actual optical parameters of the vacuum beam channel are inverted using an inverse optimization algorithm; The actual optical parameters obtained from the inversion are updated in the ideal transmission model and the dynamic focusing algorithm to correct model deviations.

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