An x-ray tube anode target control method and system

Abstract

The application provides an x-ray tube anode target control method and system, which is applied to the technical field of x-ray tube anode targets and comprises the following steps: after the system is started, self-checking and calibration are performed; a small-current electron beam is used to hit the center of each unit in sequence, corresponding deflection current values are recorded, and a coordinate-to-current lookup table is established; beam spot morphology reference calibration is performed, and initial focusing parameters are recorded; an electron beam is emitted from a cathode, sequentially passes through electrostatic focusing, magnetic focusing, grating collimation and magnetic field deflection, and finally hits a target unit; a beam probe and a target surface detector collect data in real time, the detector collects data, and a control unit processes and corrects in real time; if it is detected that the beam spot diameter deviates from a threshold value, the focusing coil current is adjusted; and if it is detected that the hitting position deviates from the center of the unit, the deflection coil current is adjusted. In this way, the positioning accuracy and real-time feedback capability of the system can be improved, and precise hitting control is achieved.

Description

Technical Field

[0001] This invention relates to the field of X-ray tube anode target technology, and in particular to a method and system for controlling an X-ray tube anode target. Background Technology

[0002] With the rapid development of next-generation high-resolution medical imaging, industrial non-destructive testing, and high-end scientific research (such as materials characterization), X-ray source systems are evolving towards higher brightness, more precise control, and longer lifespan. As one of the core components of an X-ray source, the performance of the anode target directly affects the energy distribution, spatial resolution, stability, and system efficiency of X-rays. As a key interface for generating X-rays through electron beam bombardment, the design of the anode target directly affects the focusing effect of the electron beam, thermal management capabilities, material excitation efficiency, and the reliability and lifespan of the system. Traditional anode targets are mostly made of a single material, with fixed structures and limited functions, which can hardly meet the needs of modern high-precision, dynamic, and multifunctional X-ray sources. At present, traditional anode target technology, represented by fixed materials and monolithic structures, is no longer able to cope with the challenges brought about by complex application scenarios. Specifically, existing technologies mainly face four levels of systemic limitations: First, traditional electrostatic or static magnetic focusing modes cannot compensate in real time for electron beam broadening and drift caused by space charge effects, high voltage fluctuations, and thermal deformation, making it difficult for the focal size and spatial stability of the X-ray source to reach the sub-micron level, thus limiting the ultimate resolution of imaging and analysis. Secondly, at the functional level, the single, homogeneous target structure results in fixed X-ray energy spectrum, intensity, and polarization characteristics, making dynamic adaptation and optimization impossible based on the physical properties of the sample or different imaging purposes, thus hindering system flexibility and intelligence. Furthermore, at the process control level, the lack of real-time, in-situ monitoring and feedback mechanisms for the actual electron beam bombardment position and target surface state leaves the system operating in an "open-loop" or "weak feedback" state, leading to accuracy degradation over time and under varying operating conditions, making long-term reliability and repeatability difficult to guarantee. Finally, the localized high heat load generated by continuous high-power-density electron beam bombardment easily causes melting, sputtering, or structural fatigue of traditional target materials, severely limiting the equipment's duty cycle and lifespan. However, existing technologies suffer from poor dynamic stability of the electron beam during bombardment, weak system positioning accuracy and real-time feedback capabilities, and limited functional adjustability of the anode target. Based on these shortcomings, this invention provides an X-ray tube anode target control method and system. Summary of the Invention

[0003] This invention provides a method and system for controlling an anode target in an X-ray tube, which solves the technical problems of poor dynamic stability of the electron beam during bombardment, weak positioning accuracy and real-time feedback capability of the system, and weak functional adjustability of the anode target in the prior art.

[0004] According to a first aspect of the present invention, a method for controlling an anode target in an X-ray tube is provided, comprising:

[0005] After the system starts up, it performs self-test and calibration: each unit center is bombarded sequentially with a small current electron beam, the corresponding deflection current value is recorded, and a coordinate-to-current lookup table is established; beam spot morphology benchmark calibration is performed, and the initial focusing parameters are recorded;

[0006] The user selects either a fixed-point mode or a scanning mode; the electron beam is emitted from the cathode and passes through electrostatic focusing, magnetic focusing, grating collimation, and magnetic field deflection in sequence before finally bombarding the target unit; the beam probe and target detector collect data in real time, the detector array senses the precise position of the bombardment point in real time, the control unit integrates the above path sensing data, runs intelligent control algorithms, and performs real-time processing of the collected data and closed-loop correction of the control unit.

[0007] If the beam spot diameter is detected to deviate from the threshold, the focusing coil current is adjusted; if the bombardment position is detected to deviate from the center of the unit, the deflection coil current is adjusted; the system continuously outputs a stable, parameter-adjustable X-ray beam for subsequent imaging, analysis and other applications.

[0008] According to a second aspect of the present invention, an X-ray tube anode target control system is provided, comprising: an inner permanent magnet, an outer electromagnetic element, a composite high-focusing lens, a high-performance neodymium iron boron annular permanent magnet, a magnetic yoke, a double-layer electromagnetic compensation coil, a soft magnetic alloy shielding shell, an electron beam spot, a PID controller, a multi-stage electrostatic lens group, a coaxial metal ring, a cathode, a metal focusing ring, an electrostatic focusing section, and a magnetic focusing section;

[0009] The electrostatic focusing section includes a multi-stage electrostatic lens group composed of multiple coaxial metal rings. The first stage, adjacent to the cathode, is a mechanically adjustable Wehnelt electrode. Behind the cathode, two independent metal focusing rings with slightly larger inner diameters are arranged in sequence, with each ring insulated and isolated by high-purity alumina ceramic. The independent metal focusing rings include FR1 and FR2. By applying independently adjustable negative high voltages to FR1 and FR2, a nonlinear stepped potential distribution can be formed in the axial direction.

[0010] The magnetic focusing section includes a composite high-focusing lens with an inner permanent magnet and an outer electromagnetic field; a water-cooled double-layer electromagnetic compensation coil is wound on the magnetic yoke surrounding the high-performance NdFeB ring permanent magnet; the entire lens is encapsulated by a high-permeability soft magnetic alloy shielding shell; the high-performance NdFeB ring permanent magnet establishes a strong focusing field, compressing the electron beam spot to the micrometer scale; and the double-layer electromagnetic compensation coil, based on real-time feedback signals, precisely enhances or weakens the magnetic field of the high-performance NdFeB ring permanent magnet by applying forward or reverse current; the adjustment is driven by a high-speed PID controller; the grating-magnetic field deflection system, located downstream of the composite focusing module, is used to guide the focused electron beam to a designated position on the target surface, and includes a micro-aperture beam-limiting grating and a high-speed electromagnetic deflector.

[0011] Compared with existing technologies, the advantages and positive effects of this invention are:

[0012] To address the aforementioned systemic challenges, this invention proposes and constructs a "fully closed-loop intelligent anode target system" integrating electromagnetic hybrid focusing, intelligent feedback control, and a microstructure functional array. This system achieves precise constraint and active dynamic shaping of the electron beam through an integrated electrostatic-magnetic focusing composite structure; it constructs a millisecond-level response closed-loop correction loop through active dynamic focusing based on dual sensing of beam current feedback and bombardment effect, ensuring sub-micron-level positioning and dimensional stability of the beam spot on the target surface; and through a micro-area, modular "functional unit" array target design, it empowers users with the ability to control the X-ray energy spectrum, intensity, and even polarization characteristics, enabling the output of X-rays with various energies. This solution fundamentally transforms the anode target from a passive, fixed-function component into an actively controllable, intelligently adjustable component. It not only solves traditional technical bottlenecks such as focusing accuracy, single-function limitations, process oversight, and thermal management failures, but also lays a solid technical foundation for developing next-generation high-performance X-ray equipment with adaptive, reconfigurable, and long-life characteristics.

[0013] It should be understood that the description in the Summary of the Invention is not intended to limit the key or essential features of the embodiments of the present invention, nor is it intended to restrict the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0014] The above and other features, advantages, and aspects of the various embodiments of the present invention will become more apparent from the accompanying drawings and the following detailed description. The drawings are provided for a better understanding of the invention and are not intended to limit the invention. In the drawings, the same or similar reference numerals denote the same or similar elements, wherein:

[0015] Figure 1 A flowchart of an X-ray tube anode target control method according to an embodiment of the present invention is shown;

[0016] Figure 2 A schematic diagram of a grating magnetic field deflection system for an X-ray tube anode target control method according to an embodiment of the present invention is shown.

[0017] Figure 3 A schematic diagram of a functional unit array target system for an X-ray tube anode target control method according to an embodiment of the present invention is shown.

[0018] Figure 4 A schematic diagram of an intelligent sensing and feedback system for an X-ray tube anode target control method according to an embodiment of the present invention is shown.

[0019] Figure 5A structural diagram of an X-ray tube anode target control system according to an embodiment of the present invention is shown. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this embodiment clearer, the technical solutions in this embodiment will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Furthermore, the term "and / or" in this invention is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this invention generally indicates that the preceding and following related objects have an "or" relationship.

[0022] Figure 1 A flowchart of an X-ray tube anode target control method 100 in this embodiment is shown, as follows: Figure 1 As shown, method 100 includes:

[0023] S110: After the system starts up, perform self-test and calibration: bombard the center of each unit with a small current electron beam in sequence, record the corresponding deflection current value, and establish a coordinate-to-current lookup table; perform beam spot morphology benchmark calibration and record the initial focusing parameters;

[0024] Optionally, in some embodiments, recording the initial focusing parameters specifically includes the following steps:

[0025] S111: The electron beam is emitted in a low-current mode and sequentially pre-focused by an electrostatic lens and strongly focused by a compound magnetic lens; a non-interceptor capacitive probe monitors the two-dimensional density distribution, center position, and equivalent radius of the beam spot in real time; the calibration channel includes a pinhole aperture and an imaging detector, which obtains a reference morphological image by passing the electron beam through the pinhole aperture and imaging it on the imaging detector, providing a beam spot morphological image for calibrating the inversion model of the capacitive probe and ensuring metrological accuracy for subsequent monitoring; the current parameters of the focusing lens at this time are recorded as the initial focusing reference for generating an ideal beam spot;

[0026] S112: The system controls the electron beam to precisely bombard the center of multiple pre-designed functional units on the target surface with a small current in sequence.

[0027] S113: Based on feedback, dynamically adjust the deflection current of the grating-magnetic field deflection system until the beam spot precisely hits the center of each unit; record the corresponding calibrated deflection current value for the center point of each functional unit on the target surface.

[0028] It should be noted that, in this embodiment, the grating-magnetic field deflection system is responsible for guiding the precisely focused electron beam with micrometer-level positioning accuracy and microsecond-level response speed to any designated functional unit on the anode target surface. The grating-magnetic field deflection system consists of a front-mounted micro-aperture beam-limiting grating and a rear-mounted high-speed electromagnetic deflector, and achieves precise and stable mapping from digital coordinates to physical position through intelligent control algorithms. The core of the micro-aperture beam-limiting grating is a precision through-hole processed on a high-purity tungsten sheet using microelectromechanical systems (MEMS) technology. This grating is located approximately 2 to 5 millimeters behind the composite magnetic lens, and its key function is to limit the final divergence angle of the electron beam; for example, an aperture... The 100-micrometer, 200-micrometer thick grating can limit the divergence half-angle of the electron beam to within approximately 14 degrees, thereby ensuring high collimation of the electron beam entering the deflection region and providing a clear "starting point" for subsequent high-precision deflection. At the same time, the physical position of the grating strictly defines the "virtual rotation center" of the electron beam deflection, which effectively avoids the influence of charge accumulation and thermal deformation on the reference stability. In this embodiment, the electromagnetic deflection unit is actually composed of two pairs of orthogonally placed saddle-shaped air-core coils, which control the deflection in the X and Y directions respectively. The coils are wound with low-inductance Litz wire and the double-wire parallel winding and reverse connection method ensures the generation of a uniform transverse deflection magnetic field. Each pair of coils is supplied with an equal and opposite current. Based on the Lorentz force principle, the electron beam is deflected linearly in the target plane in proportion to the current. To ensure the long-term stability of the magnetic field output, a microchannel active water cooling system is embedded inside the coil frame to control the operating temperature fluctuation within ±0.5℃, fundamentally suppressing the deflection error caused by thermal drift of the coil resistance. Before operation, a precise "coordinate-current" mapping model is established through a fully automated calibration process. Using feedback from the in-situ detector on the target surface, the current is dynamically adjusted to ensure that the electron beam accurately hits multiple reference points. A surface fitting algorithm is used to generate a continuous control function covering the entire target surface. During operation, the control unit supports multiple scanning modes. In "fixed-point mode," it can complete positioning switching within 10 microseconds based on the target unit coordinates. In "scanning mode," it can automatically generate continuous current waveforms based on the grating or vector path, driving the electron beam to perform high-speed, coherent scanning. Furthermore, the system is deeply integrated into the overall dual feedback loop, enabling it not only to execute preset paths but also to receive real-time position deviation signals from the target bombardment effect loop, dynamically fine-tuning the deflection current to actively compensate for all mechanical and thermal drift, ultimately achieving a positioning accuracy better than ±5 micrometers and extremely high repeatability. The intelligent sensing and feedback system upgrades traditional unidirectional electron beam emission to a dynamic interactive process with real-time sensing and intelligent adjustment. Advanced algorithms achieve collaborative optimization control, ensuring long-term stability and precise controllability of X-ray output characteristics from the source. A non-interceptor capacitive probe is located at the entrance of the deflection zone behind the grating.The probe consists of four precision-machined fan-shaped copper electrodes arranged in a circular cavity, with each electrode isolated by an extremely narrow insulating gap. Its working principle is based on electrostatic induction: when a collimated electron beam passes through the center of the probe at high speed, the charge distribution within the beam induces different amounts of charge on the four electrodes. By measuring the amplitude and phase difference of the induced current on each electrode and applying an inversion algorithm based on Maxwell's equations, the two-dimensional density distribution of the electron beam cross-section, the geometric center coordinates (Xb, Yb), and the equivalent radius (Rb) can be calculated in real time, with a position resolution of up to 1 micrometer and an update frequency of up to 1 MHz. An independent calibration channel is connected in parallel next to the capacitive probe. The system consists of a tungsten sheet with a Φ10-micron through-hole (serving as a pinhole aperture) and a high-speed, low-noise electron-bombardment CMOS camera behind it. The system can periodically (e.g., every 8 hours) or on command switch the electron beam path to image through the pinhole. The beam spot fluorescence image captured by the camera provides absolute reference morphological information for periodically calibrating the inversion model parameters of the capacitance probe, eliminating drift errors that may exist during long-term operation, and ensuring metrological-grade accuracy of beam monitoring. The target bombardment effect sensing unit integrates four miniaturized silicon PIN diode detectors at the perimeter of each functional unit using microfabrication technology. When the electron beam bombards a unit on the target surface... The generated backscattered electrons are asymmetrically collected by four detectors around them. The signal generation and high-precision positioning principle is as follows: the signal intensity received by each detector is strictly negatively correlated with its distance from the center of the electron beam spot. Let the signals from the four detectors be I1, I2, I3, and I4. By calculating their relative intensity ratios (e.g., (I1-I3) / (I1+I3) corresponds to the X-direction deviation, and (I2-I4) / (I2+I4) corresponds to the Y-direction deviation), the two-dimensional offset (Δx, Δy) of the electron beam spot center relative to the geometric center of the functional unit can be directly calculated with sub-micron accuracy. Simultaneously, by determining whether any detector signal drops sharply... The system can determine whether the beam spot is about to cross the unit boundary; to ensure that the electron beam accurately hits the center of the target functional unit, the input is the offset (Δx, Δy) provided by the target detector array; a lightweight convolutional neural network model is deployed in the FPGA; the network takes the raw signals or the intensity ratio of the preprocessed signals from the four detectors as input; after training, the CNN can not only output high-precision offsets, but also identify the offset patterns—for example, whether it is random instantaneous jitter, systematic drift caused by local overheating and expansion of the target surface, or regular deviation caused by deflection coil gain error; according to the error patterns identified by the CNN, the control algorithm adopts different strategies.For random jitter, a Kalman filter is used to smooth the deflection current and then fine-tune it. For systematic thermal drift, a bias signal is synchronously output to the deflection control module, and the "coordinate-current" mapping table of that unit is updated. For regular deviations, the gain parameters of the deflection coil are adjusted. The beam position (Xb, Yb) provided by the beam loop and the bombardment point deviation (Δx, Δy) provided by the target loop are jointly fed into a state observer. This observer can decouple and estimate whether the source of the error is the deflection system, mechanical deformation, or the coupling effect of the two, thus providing the most fundamental correction command. When the system performs a rapid scan, the fusion controller calculates the dynamic error caused by speed in advance according to the preset scan trajectory and injects it as a feedforward signal into both the focusing loop and the deflection loop. This signal is then superimposed on the real-time feedback signal to achieve smooth trajectory tracking. When the system detects sudden external electromagnetic interference or internal cooling fluctuations, the fusion controller can temporarily increase the sampling frequency and control bandwidth of both closed loops and activate a preset enhanced anti-interference algorithm mode to ensure the output stability of the system under transient interference. After system startup, self-testing and calibration are performed first: each unit center is bombarded sequentially with a small-current electron beam, the corresponding deflection current value is recorded, and a "coordinate-current" lookup table is established. Beam spot morphology benchmark calibration is performed, and the initial focusing parameters are recorded. Users select the operating mode via the host computer software: Point-based mode: Input the row and column number of the target cell, and the system calls the corresponding deflection current to position the electron beam at the center of that cell; Scanning mode: Set the scanning path (e.g., row scan, spiral scan), and the system automatically switches the deflection current sequentially to achieve dynamic imaging; The electron beam is emitted from the cathode, passing through electrostatic focusing, magnetic focusing, grating collimation, and magnetic field deflection in sequence, finally bombarding the target cell; The beam probe and target detector collect data in real time, implementing real-time data processing and closed-loop correction of the control unit; If the beam spot diameter deviates from the threshold, the focusing coil current is adjusted; If the bombardment position deviates from the center of the cell, the deflection coil current is adjusted; The correction cycle time is short, ensuring stability during long-term operation; The system continuously outputs a stable, parameter-adjustable X-ray beam for subsequent imaging, analysis, and other applications (see appendix for details). Figure 2 Appendix Figure 3 and appendix Figure 4 , attached Figure 2 A grating in the middle, B grounding to prevent charge; attached Figure 3 C. High thermal conductivity diamond / pyrolytic graphite, liquid-cooled contact on the back, laser-polished coated bearing surface; D. High atomic number material W / Au / Re; E. Medium to low atomic number material Mo / Ag / Cu; F. Composite material structure nanoporous tungsten / W-Si multilayer film / W-Cu gradient; G. Electron beam-guided bombardment of multilayer film with polarization output; H. Generation of characteristic X-rays; J. Thickness-adjustable strength. Figure 4K is a non-interceptor capacitive probe consisting of four fan-shaped copper electrodes, used to detect differences in induced charge and calculate the beam center and cross-sectional shape; a tungsten aperture and camera achieve visual calibration of the beam spot morphology; L is beam loop control, using the capacitive probe signal and algorithm to adjust the magnetic moment coil current and maintain the beam spot diameter; D is high atomic number material W / Au / Re; E is medium to low atomic number material Mo / Ag / Cu; F is a composite material structure nanoporous tungsten / W-Si multilayer film / W-Cu gradient; G is electron beam positioning bombardment of multilayer film polarization output; H generates characteristic X-rays).

[0029] S120: The user selects either a fixed-point mode or a scanning mode; the electron beam is emitted from the cathode, passing through electrostatic focusing, magnetic focusing, grating collimation, and magnetic field deflection in sequence, finally bombarding the target unit; the beam probe and target detector collect data in real time, the detector array senses the precise position of the bombardment point in real time, and the control unit integrates the above path sensing data and runs an intelligent control algorithm; the non-interceptor beam probe located in the optical path monitors the beam spot shape and position in real time, while the miniature detector array around each unit of the target surface senses the precise position of the bombardment point in real time; the control unit integrates the path sensing data and runs an intelligent control algorithm (including PID, feedforward compensation, and CNN-based pattern recognition) to implement real-time processing of the collected data and closed-loop correction of the control unit;

[0030] Optionally, in some embodiments, real-time processing of the acquired data and closed-loop calibration of the control unit are implemented, specifically including the following steps:

[0031] S121: The user selects the working mode and sets parameters through the host computer. If the fixed-point mode is selected, the target cell row and column number is entered, and the system calls the corresponding deflection current to position the electron beam at the center of the cell. If the scanning mode is selected, the scanning path is set, and the system automatically switches the deflection current in sequence to form dynamic imaging. If the row and column coordinates of the target functional cell are entered, the system will call the corresponding deflection current parameters from the lookup table. If the scanning path is set, the system will automatically generate a continuous deflection current waveform sequence.

[0032] S122: The electron beam emitted from the cathode undergoes large-scale, low-power pre-focusing and preliminary shaping through a multi-stage electrostatic lens group; the electron beam enters a composite strong focusing lens with an inner permanent magnet and an outer electromagnetic coil; the permanent magnet provides a powerful basic focusing field, compressing the beam spot to the micrometer level; the electromagnetic coil is finely adjusted according to real-time feedback.

[0033] S123: The focused electron beam passes through the micro-aperture beam-limiting grating, and its divergence angle is strictly limited, defining a clear virtual rotation center of deflection; the high-speed electromagnetic deflector generates a precise transverse magnetic field according to the received current command, guiding the highly collimated electron beam to the specified coordinate point on the target surface.

[0034] S124: Throughout the bombardment process, the capacitive probe continuously monitors the real-time shape and center position of the electron beam in flight at a frequency of up to 1MHz; the PIN diode detector array on the target surface synchronously senses the submicron level deviation of the actual bombardment point of the electron beam spot relative to the geometric center of the functional unit.

[0035] It should be noted that, in this embodiment, the electron beam is precisely positioned to a target unit through a deflection system; different material units generate different characteristic X-ray spectra after being bombarded; the output intensity of X-rays is adjusted by thickness variation; the traditional unidirectional electron beam emission is upgraded to a dynamic interactive process with real-time sensing and intelligent adjustment; collaborative optimization control is achieved through advanced algorithms, thereby ensuring the long-term stability and precise controllability of X-ray output characteristics from the source; the multilayer film structure unit can generate partially polarized X-ray output based on the Bragg diffraction principle; a functional unit array target design composed of micro-areas and multiple materials is adopted; the substrate: high thermal conductivity diamond or pyrolytic graphite material is used, and the back side is in direct contact with the liquid cooling system to ensure efficient heat dissipation. The substrate surface is laser polished and coated to form a highly flat bearing surface. Functional units: Array-like units are fabricated on the substrate using microfabrication processes such as photolithography, sputtering, and electroplating. The unit materials are designed according to different needs: high atomic number materials such as tungsten (W), gold (Au), and rhenium (Re) are used to generate high-energy characteristic X-rays; medium and low atomic number materials such as molybdenum (Mo), silver (Ag), and copper (Cu) are used for conventional energy dispersive spectroscopy analysis; composite material structures such as nanoporous tungsten (porosity 20-40%), W / Si multilayer films, and gradient composition materials (such as W-Cu gradient) are used to control the X-ray energy spectrum, intensity, and polarization characteristics. Functional implementation: The electron beam is precisely positioned to a target unit through a deflection system; different material units produce different characteristic X-ray spectra after being bombarded; the output intensity of X-rays is adjusted by thickness variation; multilayer film structure units can generate partially polarized X-ray output based on the Bragg diffraction principle.

[0036] S130: If the beam spot diameter is detected to deviate from the threshold, the focusing coil current is adjusted; if the bombardment position is detected to deviate from the center of the unit, the deflection coil current is adjusted; the correction cycle time is short, ensuring stability under long-term operation; the system continuously outputs a stable, parameter-adjustable X-ray beam for subsequent imaging, analysis and other applications.

[0037] Optionally, in some embodiments, adjusting the deflection coil current specifically includes the following steps:

[0038] S131: The deviation between the beam spot size measured in real time by the capacitor probe and the set value is used as input; the digital PID combined with the feedforward compensation algorithm calculates the current correction amount required for the fine-tuning coil in the composite magnetic lens, actively offsetting the beam spot widening or jitter caused by space charge effect, high voltage fluctuation, etc., and dynamically stabilizing the beam spot diameter fluctuation within the set threshold.

[0039] S132: The bombardment point offset provided by the PIN diode detector is used as input; a lightweight convolutional neural network model deployed on FPGA identifies error patterns, and the control algorithm adopts different strategies according to the preset strategy, and fine-tunes the deflection current in real time to ensure that the bombardment point is always locked at the center of the target.

[0040] S133: Comprehensively analyzes the error information from the focusing ring and deflection ring, determines the root cause of the error, and issues a correction command; during high-speed scanning, the controller will pre-calculate and inject dynamic error feedforward signals according to the preset trajectory to achieve smooth trajectory tracking;

[0041] S134: When a sudden interference is detected, the controller can temporarily increase the control bandwidth of the dual loop and start the enhanced anti-interference mode; based on the calibration result, it outputs an electron beam probe that meets the preset standard.

[0042] It should be noted that, in this embodiment, the grating-magnetic field deflection system is responsible for guiding the precisely focused electron beam with micrometer-level positioning accuracy and microsecond-level response speed to any designated functional unit on the anode target surface. This system consists of a front-mounted micro-aperture beam-limiting grating and a rear-mounted high-speed electromagnetic deflector, achieving precise and stable mapping from digital coordinates to physical position through intelligent control algorithms. The core of the micro-aperture beam-limiting grating is a precision through-hole processed on a high-purity tungsten sheet using microelectromechanical systems (MEMS) technology. This grating is located approximately 2 to 5 millimeters behind the composite magnetic lens, and its key function is to limit the final divergence angle of the electron beam. For example, a grating with an aperture of 100 micrometers and a thickness of 200 micrometers can limit the divergence half-angle of the electron beam to within approximately 14 degrees, thereby ensuring high collimation of the electron beam entering the deflection region, which is crucial for subsequent... The high-precision deflection provides a clear "starting point"; at the same time, the physical position of the grating strictly defines the "virtual rotation center" of the electron beam deflection, which effectively avoids the influence of charge accumulation and thermal deformation on the reference stability; the electromagnetic deflection unit is actually composed of two pairs of orthogonally placed saddle-shaped air-core coils, which control the deflection in the X and Y directions respectively; the coils are wound with low-inductance Litz wire, and the double-wire parallel winding and reverse connection method ensures the generation of a uniform transverse deflection magnetic field; each pair of coils is supplied with current of equal magnitude and opposite direction, and according to the Lorentz force principle, the electron beam generates a linear deflection in the target plane that is proportional to the current. To ensure long-term stability of the magnetic field output, a microchannel active water-cooling system is embedded inside the coil frame, controlling operating temperature fluctuations within ±0.5℃, fundamentally suppressing deflection errors caused by thermal drift of the coil resistance. The deflection control mechanism involves establishing a precise "coordinate-current" mapping model through a fully automated calibration process before operation. Utilizing feedback from the in-situ detector on the target surface, the current is dynamically adjusted to ensure the electron beam accurately hits multiple reference points. A surface fitting algorithm is then used to generate a continuous control function covering the entire target surface. During operation, the control unit supports multiple scanning modes. In "fixed-point mode," positioning switching can be completed within 10 microseconds based on the target unit coordinates. In "scanning mode," a continuous current waveform is automatically generated based on the grating or vector path, driving the electron beam for high-speed, continuous scanning. Furthermore, the system is deeply integrated into the overall dual feedback loop, which not only executes the preset path, but also receives the real-time position deviation signal from the target bombardment effect loop, and dynamically fine-tunes the deflection current, thereby actively compensating for all mechanical and thermal drift, and ultimately achieving a positioning accuracy of better than ±5 micrometers and extremely high repeatability.

[0043] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the described module can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0044] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, because according to the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are all optional embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0045] The above is an introduction to the method embodiments. The following describes the solution of the present invention further through device embodiments.

[0046] Figure 5 A block diagram of an X-ray tube anode target control system according to an embodiment of the present invention is shown. The system includes: an inner permanent magnet 1, an outer electromagnetic element 2, a composite high-focusing lens 3, a high-performance neodymium iron boron ring permanent magnet 4, a magnetic yoke 5, a double-layer electromagnetic compensation coil 6, a soft magnetic alloy shielding shell 7, an electron beam spot 8, a PID controller 9, a multi-stage electrostatic lens group 10, a coaxial metal ring 11, a cathode 12, a metal focusing ring 13, an electrostatic focusing section 14, and a magnetic focusing section 15;

[0047] The electrostatic focusing section 14 includes a multi-stage electrostatic lens group 10 composed of multiple coaxial metal rings 11. The first stage, adjacent to the cathode 12, is a mechanically adjustable Wehnelt electrode, which applies an independently programmable negative bias voltage. This is responsible for controlling the effective emission area of ​​the cathode and initially focusing the beam. Behind the cathode 12, two independent metal focusing rings 13 with slightly larger inner diameters are arranged in sequence, and the rings are insulated and isolated by high-purity alumina ceramic. The independent metal focusing rings 13 include FR1 and FR2. By applying independently adjustable negative high voltages to FR1 and FR2 respectively, a nonlinear stepped potential distribution can be formed in the axial direction.

[0048] The magnetic focusing section 15 includes a composite high-focusing lens 3 consisting of an inner permanent magnet 1 and an outer electromagnetic element 2. Its physical structure is based on a high-performance neodymium iron boron ring permanent magnet 4, which can provide a stable axial focusing magnetic field of up to about 0.3T. A water-cooled double-layer electromagnetic compensation coil 6 is precisely wound on the magnetic yoke 5 surrounding the high-performance neodymium iron boron ring permanent magnet 4. The entire lens is encapsulated by a high-permeability soft magnetic alloy shielding shell 7 to isolate external interference and constrain the internal magnetic field. Its dynamic control mechanism is based on the principle of permanent magnet main focusing and electromagnetic fine adjustment: the high-performance neodymium iron boron ring permanent magnet 4 establishes a strong focusing field, compressing the electron beam spot 8 to the micrometer level; while the double-layer electromagnetic compensation coil 6, based on real-time feedback signals, finely enhances or weakens the magnetic field of the high-performance neodymium iron boron ring permanent magnet 4 by passing forward or reverse current. The adjustment is driven by a high-speed PID controller 9, which can respond to beam current changes within 100 microseconds and offset beam spot broadening or drift caused by space charge repulsion, high voltage fluctuations, or thermal deformation in real time.

[0049] In this embodiment, high thermal conductivity diamond or pyrolytic graphite material is used, with the back side in direct contact with the liquid cooling system to ensure efficient heat dissipation. The substrate surface is laser polished and coated to form a highly flat bearing surface; array-type units are fabricated on the substrate using micro-machining processes such as photolithography, sputtering, and electroplating. The composite focusing module of this invention is a precision electro-optical system integrating multi-segment independently controllable electrostatic lenses and permanent magnet-electromagnetic composite magnetic lenses. Its core design concept lies in adopting a hierarchical control mechanism: firstly, the electrostatic lens is used for large-scale, low-power pre-focusing and preliminary beam morphology shaping; then, the composite magnetic lens is used for high-intensity, high-precision, and dynamically fine-tunable final focusing. The two-stage system works closely together in axial space to form a closed-loop control of the high current density electron beam from emission to target bombardment. The electrostatic focusing part is specifically embodied in a multi-stage electrostatic lens group. This part is an innovation based on the traditional Wehnelt electrode, consisting of multiple coaxial metal rings. The first stage, adjacent to the cathode, is a mechanically adjustable Wehnelt electrode (typically ranging from Φ1.0mm to Φ3.0mm), which applies an independently programmable negative bias voltage (typically ranging from -100V to -500V) to control the effective emission area of ​​the cathode and initially converge the beam. Behind it, two independent metal focusing rings (FR1 and FR2) with slightly larger inner diameters are arranged sequentially, with each ring insulated by high-purity alumina ceramic. By applying independently adjustable negative high voltages to FR1 and FR2, a nonlinear stepped potential distribution can be formed along the axis. This multi-stage electric field structure can generate multiple consecutive converging forces on the traveling electron beam, achieving a smoother pre-focusing effect with less aberration than single-stage focusing, and effectively pre-adjusting the position and size of the electron beam to provide optimal incident conditions for the subsequent magnetic lens. The core of the magnetic focusing section is a composite strong focusing lens with an inner permanent magnet and an outer electromagnetic field. Its physical structure is based on a high-performance neodymium iron boron ring permanent magnet, which can provide a stable axial focusing magnetic field of up to approximately 0.3T. The system is based on a fundamental principle: a double-layered electromagnetic compensation coil with a water-cooled structure is precisely wound on the magnetic yoke surrounding the permanent magnet; the entire lens is encapsulated in a high-permeability soft magnetic alloy shielding shell to isolate external interference and constrain the internal magnetic field; its dynamic control mechanism is based on the principle of "permanent magnet main focusing, electromagnetic fine adjustment": the permanent magnet establishes a strong focusing field, compressing the electron beam spot to the micrometer level; while the electromagnetic coil, based on real-time feedback signals, finely "enhances" or "weakens" the magnetic field of the permanent magnet by passing forward or reverse current; this adjustment is driven by a high-speed PID controller, which can respond to beam current changes within 100 microseconds, and in real time cancel out beam spot broadening or drift caused by space charge repulsion, high voltage fluctuations, or thermal deformation; through the synergistic mechanism of "electrostatic preforming, strong magnetic focusing, and electromagnetic dynamic phase locking", the system ultimately achieves dynamic stabilization of the beam spot diameter within 30 micrometers and long-term stability better than ±5 micrometers, providing a highly stable and size-controllable electron beam probe for the entire system, laying the foundation for high-resolution imaging and accurate material analysis.

[0050] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the described module can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0051] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this invention does not impose any limitations on them.

[0052] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for controlling an anode target in an X-ray tube, characterized in that, include: After the system starts up, it performs self-test and calibration: each unit center is bombarded sequentially with a small current electron beam, the corresponding deflection current value is recorded, and a coordinate-to-current lookup table is established. The beam spot morphology benchmark calibration and initial focusing parameters are recorded, including the following steps: An electron beam is emitted in a low-current mode, sequentially pre-focused by an electrostatic lens and strongly focused by a compound magnetic lens; a non-interceptor capacitive probe monitors the two-dimensional density distribution, center position, and equivalent radius of the beam spot in real time; the calibration channel includes a pinhole aperture and an imaging detector, and a benchmark morphology image is obtained by passing the electron beam through the pinhole aperture and imaging it on the imaging detector, providing a beam spot morphology image; the current parameters of the focusing lens are recorded as the initial focusing benchmark for generating an ideal beam spot; the system controls the electron beam to precisely bombard the centers of multiple pre-designed functional units on the target surface with a low current; based on feedback, the deflection current of the grating-magnetic field deflection system is dynamically adjusted until the beam spot accurately hits the center of each unit; for the center point of each functional unit on the target surface, the corresponding calibrated deflection current value is recorded; The user selects either a fixed-point mode or a scanning mode; the electron beam is emitted from the cathode and passes through electrostatic focusing, magnetic focusing, grating collimation and magnetic field deflection in sequence before finally bombarding the target unit; the beam probe and target detector collect data in real time, the detector array senses the precise position of the bombardment point in real time, and the control unit fuses the path sensing data and runs an intelligent control algorithm. If the beam spot diameter is detected to deviate from the threshold, the focusing coil current is adjusted; if the bombardment position is detected to deviate from the center of the unit, the deflection coil current is adjusted; the system continuously outputs a stable, parameter-adjustable X-ray beam. Implementing real-time processing of acquired data and closed-loop calibration of the control unit includes the following steps: Users select the working mode and set parameters via the host computer. If the fixed-point mode is selected, the target cell row and column number is entered, and the system calls the corresponding deflection current to position the electron beam at the center of the cell. If the scanning mode is selected, the scanning path is set, and the system automatically switches the deflection current in sequence to form dynamic imaging. If the row and column coordinates of the target functional cell are entered, the system will call the corresponding deflection current parameters from the lookup table. If the scanning path is set, the system will automatically generate a continuous deflection current waveform sequence. The electron beam emitted from the cathode undergoes large-scale, low-power pre-focusing and preliminary shaping through a multi-stage electrostatic lens group; the electron beam enters a composite strong focusing lens with an inner permanent magnet and an outer electromagnetic coil; the permanent magnet provides a powerful basic focusing field, compressing the beam spot to the micrometer level; and the electromagnetic coil is finely adjusted according to real-time feedback. The focused electron beam passes through a micro-aperture beam-limiting grating, and its divergence angle is strictly limited, defining a clear virtual center of deflection. The high-speed electromagnetic deflector generates a precise transverse magnetic field according to the received current command, guiding the highly collimated electron beam to the specified coordinate point on the target surface. Throughout the bombardment process, the capacitive probe continuously monitors the real-time morphology and center position of the electron beam in flight at a frequency of 1MHz; the PIN diode detector array on the target surface synchronously senses the submicron-level deviation of the actual bombardment point of the electron beam spot relative to the geometric center of the functional unit.

2. The X-ray tube anode target control method according to claim 1, characterized in that, The grating-magnetic field deflection system guides a focused electron beam to any designated functional unit on the anode target surface with micron-level positioning accuracy and microsecond-level response speed. The grating-magnetic field deflection system consists of a front-mounted micro-aperture beam-limiting grating and a rear-mounted high-speed electromagnetic deflector, achieving precise and stable mapping from digital coordinates to physical position. The core of the micro-aperture beam-limiting grating is a precision through-hole processed on a high-purity tungsten sheet using microelectromechanical systems (MEMS) technology. The micro-aperture beam-limiting grating is located 2 to 5 millimeters behind the composite magnetic lens, limiting the final divergence angle of the electron beam.

3. The X-ray tube anode target control method according to claim 2, characterized in that, The electromagnetic deflection unit of the grating-magnetic field deflection system consists of two pairs of orthogonally placed saddle-shaped air-core coils, which control the deflection in the X and Y directions respectively. The saddle-shaped air-core coils are wound with low-inductance Litz wire and generate a transverse deflection magnetic field by double-wire parallel winding and reverse connection. Each pair of saddle-shaped air-core coils is supplied with currents of equal magnitude and opposite direction. According to the Lorentz force principle, the electron beam produces a linear deflection in the target plane that is proportional to the current. Before operation, a coordinate-current mapping model is established through a fully automated calibration process. The current is dynamically adjusted using feedback from the in-situ detector on the target surface to ensure that the electron beam accurately hits multiple reference points. A surface fitting algorithm is used to generate a continuous control function covering the entire target surface.

4. The X-ray tube anode target control method according to claim 2, characterized in that, The non-interceptor capacitive probe of the grating-magnetic field deflection system is located at the entrance of the deflection region behind the grating. The non-interceptor capacitive probe consists of four fabricated fan-shaped copper electrodes surrounding a circular cavity, with each electrode isolated by an extremely narrow insulating gap. When the collimated electron beam passes through the center of the probe at high speed, the charge distribution inside the beam induces different amounts of charge on the four electrodes. By measuring the amplitude and phase difference of the induced current on each electrode, the two-dimensional density distribution, geometric center coordinates, and equivalent radius of the electron beam cross-section are calculated in real time. An independent calibration channel is connected in parallel next to the non-interceptor capacitive probe. The calibration channel consists of a tungsten sheet with a Φ10-micron through-hole and an electron bombardment CMOS camera behind it. The electron beam path is switched periodically or on command, and imaging is performed through the pinhole. The beam spot fluorescence image captured by the camera provides absolute reference morphological information for periodically calibrating the inversion model parameters of the capacitive probe.

5. The X-ray tube anode target control method according to claim 1, characterized in that, The target bombardment effect sensing unit integrates four miniaturized silicon PIN diode detectors at the perimeter of each functional unit using microfabrication technology. When an electron beam bombards a functional unit on the target surface, the resulting backscattered electrons are asymmetrically collected by the four detectors around it. The signal intensity received by each detector is strictly negatively correlated with its distance from the center of the electron beam spot. Let the signals of the four detectors be I1, I2, I3, and I4. By calculating their relative intensity ratio, the two-dimensional offset of the electron beam spot center relative to the geometric center of the functional unit is calculated. At the same time, by judging whether there is a sharp drop in the detector signal, it is determined whether the beam spot is about to cross the unit boundary.

6. The X-ray tube anode target control method according to claim 5, characterized in that, The electron beam hits the center of the target functional unit, with the input being the offset provided by the target detector array. A lightweight convolutional neural network model is deployed in the FPGA. The FPGA takes the raw signals or the intensity ratio of the preprocessed signals from the four detectors as input. Based on the error patterns identified by the convolutional neural network model, the control algorithm adopts different strategies. For random jitter, a Kalman filter is used to smooth the signal and then a fine-tuning amount of the deflection current is given. For systematic thermal drift, a bias signal is synchronously output to the deflection control module, and the coordinate-current mapping table of the functional unit is updated. For regular deviations, the gain parameters of the deflection coil are adjusted. The deviation between the beam position provided by the beam loop and the bombardment point provided by the target loop is sent to a state observer. The source of the error is decoupled and estimated to be the deflection system, mechanical deformation, or the coupling effect of both, and the most fundamental correction command is given.

7. The X-ray tube anode target control method according to claim 1, characterized in that, Adjusting the deflection coil current includes the following steps: The deviation between the beam spot size measured in real time by the capacitor probe and the set value is used as input; the digital PID combined with the feedforward compensation algorithm calculates the current correction required for the fine-tuning coil in the composite magnetic lens, actively counteracts the beam spot widening or jitter caused by space charge effect, high voltage fluctuation, etc., and dynamically stabilizes the beam spot diameter fluctuation within the set threshold. The impact point offset provided by the PIN diode detector is used as input; a lightweight convolutional neural network model deployed on an FPGA identifies error patterns, and the control algorithm adopts different strategies according to the preset strategy, and fine-tunes the deflection current in real time to ensure that the impact point is always locked at the center of the target. By comprehensively analyzing the error information from the focusing ring and deflection ring, determining the root cause of the error, and issuing a correction command, the controller will pre-calculate and inject dynamic error feedforward signals based on the preset trajectory during high-speed scanning to achieve smooth trajectory tracking. When a sudden interference is detected, the controller can temporarily increase the control bandwidth of the dual loop and start the enhanced anti-interference mode; based on the calibration results, it outputs an electron beam probe that meets the preset standard.

8. An X-ray tube anode target control system, used to implement the X-ray tube anode target control method according to any one of claims 1-7, characterized in that, include: Internal permanent magnet, external electromagnetic, composite high-focusing lens, high-performance neodymium iron boron ring permanent magnet, magnetic yoke, double-layer electromagnetic compensation coil, soft magnetic alloy shielding shell, electron beam spot, PID controller, multi-stage electrostatic lens group, coaxial metal ring, cathode, metal focusing ring, electrostatic focusing part and magnetic focusing part; The electrostatic focusing section includes a multi-stage electrostatic lens group composed of multiple coaxial metal rings. The first stage, adjacent to the cathode, is a mechanically adjustable Wehnelt electrode. Behind the cathode, two independent metal focusing rings with slightly larger inner diameters are arranged in sequence, with each ring insulated and isolated by high-purity alumina ceramic. The independent metal focusing rings include FR1 and FR2. By applying independently adjustable negative high voltages to FR1 and FR2, a nonlinear stepped potential distribution can be formed in the axial direction. The magnetic focusing section includes a composite high-focusing lens with an inner permanent magnet and an outer electromagnetic field; a water-cooled double-layer electromagnetic compensation coil is wound on the magnetic yoke surrounding the high-performance NdFeB ring permanent magnet; the entire lens is encapsulated by a high-permeability soft magnetic alloy shielding shell; the high-performance NdFeB ring permanent magnet establishes a strong focusing field, compressing the electron beam spot to the micrometer scale; and the double-layer electromagnetic compensation coil, based on real-time feedback signals, strengthens or weakens the magnetic field of the high-performance NdFeB ring permanent magnet by applying forward or reverse current; the adjustment is driven by a high-speed PID controller; the grating-magnetic field deflection system, located downstream of the composite focusing module, is used to guide the focused electron beam to a designated position on the target surface, and includes a micro-aperture beam-limiting grating and a high-speed electromagnetic deflector.

Images