Beam uniformity improvement method and device based on transverse excitation sweep curve

Abstract

This invention provides a method and apparatus for improving beam uniformity based on a transverse excitation amplitude modulation curve, relating to the field of particle accelerator technology. The method includes: Step S1, establishing an excitation amplitude modulation curve in polynomial function form and initializing the polynomial coefficients of the excitation amplitude modulation curve; Step S2, during beam modulation in the accelerator, the control program generates and distributes the initialized excitation amplitude modulation curve, applies a corresponding voltage value to the transverse excitation plate, records the change in the number of beam particles during extraction in the extraction line or terminal ionization chamber, and feeds the change information back to the control program; Step S3, the control program adjusts the polynomial coefficients based on the feedback results of the extracted beam; Step S4, repeating steps S2 to S3 until the measured uniformity of the extracted beam meets the predetermined requirements, then stopping the feedback and determining the optimal excitation amplitude modulation curve; Step S5, the control program adjusts the beam extraction time structure based on the optimal excitation amplitude modulation curve.

Description

Technical Field

[0001] This invention relates to the field of particle accelerator technology, and in particular to a method and device for improving beam uniformity based on transverse excitation sweep curve. Background Technology

[0002] Medical accelerators, currently the most advanced radiotherapy devices internationally, can accelerate proton beams to 230 MeV and heavy ion beams (mainly carbon ions) to 430 MeV / µs, then deliver them to various treatment terminals. Their key feature is the full utilization of the energy deposition from the inverted Bragg peak during proton / heavy ion beam penetration, minimizing damage to normal tissues. Simultaneously, they effectively break the double helix of tumor cell DNA, inhibiting recurrence. Due to minimal side effects and controllable ion beams, they also enable precise treatment of tumors in complex organs.

[0003] As a core component of medical devices, the accelerator synchrotron ring is responsible for ion beam accumulation, storage, and acceleration. The device's performance significantly impacts the beam quality at the treatment endpoint, thus placing higher demands on synchrotron ring design. After the beam is accelerated to the specified energy, considering the dose requirements of the human body, a slow extraction method is often used to transmit the beam to subsequent beamlines within the synchrotron ring. Beam extraction efficiency, uniformity, and duty cycle are important indicators for evaluating the slow extraction design of the device. Summary of the Invention

[0004] In view of the above problems, the present invention provides a method and device for improving beam uniformity based on transverse excitation sweep curve, so as to improve the uniformity of beam extraction.

[0005] The first aspect of the present invention provides a method for improving beam uniformity based on a transverse excitation amplitude modulation curve, comprising: step S1, establishing an excitation amplitude modulation curve in the form of a polynomial function, and initializing the polynomial coefficients of the excitation amplitude modulation curve; step S2, during the beam modulation process of the accelerator, the control program generates and issues the initialized excitation amplitude modulation curve, applies a corresponding voltage value to the transverse excitation plate, records the change information of the number of beam particles during the extraction process in the lead-out beam or terminal ionization chamber, and feeds back the change information to the control program; step S3, the control program adjusts the polynomial coefficients according to the feedback result of the extracted beam to update the excitation amplitude modulation curve; step S4, repeating steps S2 to S3 until the measured uniformity of the extracted beam reaches a predetermined requirement, stopping the feedback, and determining the optimal excitation amplitude modulation curve; step S5, the control program adjusts the beam extraction time structure according to the optimal excitation amplitude modulation curve.

[0006] According to an embodiment of the present invention, the polynomial function is a sixth-degree polynomial, and the excitation amplitude modulation curve is initialized as follows:

[0007] θRF-KO =A1t+A2t 2 +A3t 3 +A4t 4 +A5t 5 +A6t 6 +C

[0008] In the formula, t is the extraction time; θ RF-KO , where is the sweep kick angle of the lateral excitation; A1, A2, ..., A6, C are the polynomial coefficients to be adjusted.

[0009] According to an embodiment of the present invention, step S3 includes: step S31, the control program divides the beam extraction process into multiple extraction time periods based on the feedback result of the beam uniformity; step S32, in different extraction time periods, the slope magnitude and / or slope change degree of the excitation amplitude modulation curve are different.

[0010] According to an embodiment of the present invention, the multiple lead-out time periods include a lead-out start segment, a lead-out mid-early segment, a lead-out mid-late segment, and a lead-out end segment, wherein: in the lead-out start segment, a first sweep angle is set, and then the first sweep angle is reduced to a second sweep angle; in the lead-out mid-early segment, the slope of the excitation amplitude modulation curve fluctuates or remains stable within a first preset amplitude range; in the lead-out mid-late segment, the slope of the excitation amplitude modulation curve is gradually increased within a second preset amplitude range; in the lead-out end segment, the slope of the excitation amplitude modulation curve is gradually increased within a third preset amplitude range, wherein the third preset amplitude range is greater than the second preset amplitude range.

[0011] According to an embodiment of the present invention, the control program is included in the beam tuning software used in the accelerator's central control room.

[0012] According to an embodiment of the present invention, the method is applied in the slow-extraction mode of an accelerator, including a medical accelerator.

[0013] According to an embodiment of the present invention, in step S2, the terminal ionization chamber is placed at an external terminal connected to the accelerator.

[0014] A second aspect of the present invention provides an electronic device comprising: one or more processors; and a memory for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors cause the one or more processors to implement the method described above.

[0015] A third aspect of the present invention provides a computer-readable storage medium having executable instructions stored thereon, which, when executed by a processor, cause the processor to perform the above-described method.

[0016] Compared with the prior art, the beam uniformity improvement method and device based on the transverse excitation sweep curve provided by the present invention have at least the following beneficial effects:

[0017] (1) The present invention can effectively improve the traditional transverse excitation, making the time structure of the slow-extracted beam more uniform and improving the treatment efficiency. The actual beam adjustment process is simple and efficient, without adding any additional components.

[0018] (2) In actual accelerator operation, the excitation control program can generate different excitation curves by simply changing the polynomial coefficients, which can more effectively adjust the extraction beam time structure under different emittances. Attached Figure Description

[0019] The above and other objects, features and advantages of the present invention will become more apparent from the following description of embodiments of the invention with reference to the accompanying drawings, in which:

[0020] Figure 1 The diagram schematically illustrates the structure of the excitation element in a commonly used slow extraction scheme.

[0021] Figure 2 The excitation curves in a commonly used slow extraction scheme are illustrated, where (a) is the excitation sweep curve and (b) is the amplitude modulation curve.

[0022] Figure 3 A flowchart illustrating a method for improving beam uniformity based on a transverse excitation sweep curve according to an embodiment of the present invention is shown.

[0023] Figure 4 A flowchart illustrating the adjustment of polynomial coefficients according to an embodiment of the present invention is shown.

[0024] Figure 5 The diagram schematically illustrates a theoretical amplitude modulation curve and a polynomial form transverse excitation amplitude modulation curve according to an embodiment of the present invention, wherein (a) is the theoretical amplitude modulation curve and (b) is a polynomial form transverse excitation amplitude modulation curve.

[0025] Figure 6 The diagram schematically illustrates the extraction beam time structure under the theoretical amplitude modulation curve and the polynomial form transverse excitation amplitude modulation curve according to an embodiment of the present invention, wherein (a) is the extraction beam time structure corresponding to the theoretical amplitude modulation curve, and (b) is the extraction beam time structure corresponding to the polynomial form transverse excitation amplitude modulation curve.

[0026] Figure 7 The schematic diagram illustrates the principle of the method according to an embodiment of the present invention in actual beam tuning.

[0027] Figure 8 A block diagram of an electronic device suitable for implementing a beam uniformity improvement method based on a transverse excitation sweep curve, according to an embodiment of the present invention, is shown schematically. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and 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.

[0029] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0030] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0031] The commonly used slow extraction scheme for accelerators involves using a quadrupole magnet to adjust the horizontal operating point of the synchrotron ring to near the 1 / 3 resonance line on the extraction platform, using a hexapole magnet to form a specific triangular phase stabilization region, and then gradually increasing the oscillation amplitude of the stable particles under the action of transverse excitation (such as RF-KO, high-frequency kick-out) until extraction is finally achieved.

[0032] In such Figure 1 In the commonly used slow extraction scheme shown, the voltage signal is applied to two horizontal excitation plates after passing through a power amplifier and impedance transformer, thereby forming a transverse electric field to deflect the beam. To ensure high beam extraction efficiency and uniformity, the transverse excitation mode often adopts a frequency-sweep and amplitude-sweep mode, that is, the plate voltage will vary with different frequencies and amplitudes. Figure 2 The figures show the excitation sweep curve and amplitude modulation curve, respectively. Generally, the sweep bandwidth needs to cover the cyclotron frequencies of all ions within the ring to ensure that each particle can resonate with the excitation and be extracted. The excitation amplitude gradually increases with the increase in the number of extracted particles and the decrease in the cyclic beam emittance, used to adjust beam uniformity. Transverse excitation does not change the accelerator ring optics and has a short beam cutoff time, thus it has been widely used.

[0033] Lateral excitation primarily adjusts the overall uniformity of the beam extraction through the amplitude curve, such as... Figure 2As shown in (b), the slope of the curve increases with time. In the initial extraction segment, since the beam emittance and the size of the phase-stable region are not significantly different, only a small kick angle is needed to extract the beam. As time progresses, the number of extracted particles increases, the beam emittance decreases, and the excitation kick angle needs to become increasingly larger to provide a greater kick angle to expel the particles at the center of the beam nucleus. The derivation process of this amplitude curve theoretical model is roughly as follows:

[0034] Assuming that the transverse phase space distribution of particles within the ring is Gaussian at any given moment after beam extraction, then the Rayleigh distribution function p(r) along the radial direction is:

[0035]

[0036] σ 2 =2ε rms

[0037] Where σ is the standard deviation of the Rayleigh distribution; ε rms denoted as root mean square radii; r is the radius in the Rayleigh distribution; p(r) is the corresponding Rayleigh distribution equation.

[0038] Let r0 be the boundary of the stable region in the Rayleigh distribution. A particle is considered to have been extracted when its radius r > r0. The number of extracted particles N under different number of cycles n is also discussed. ext It can be represented as:

[0039]

[0040] Where N0 is the total number of particles in the ring; σ 2 (n) represents the variance of the Rayleigh distribution at different number of cycles n.

[0041] Therefore, the beam extraction time structure can be obtained. for:

[0042]

[0043]

[0044] ΔQ=q k -q

[0045] ε x =4ε rms

[0046] Where, β x ε is the beta function at the lateral excitation position; θ is the excitation kick angle; ε x q represents the horizontal emittance of 2σ; ΔQ is the fractional difference between the operating point of the particles in the cluster and the designed operating point of the synchronization loop; k q represents the fractional part of the operating point of different particles in the cluster; q represents the fractional part of the operating point of the synchronization loop design.

[0047] Assume σ 2 (n) is directly proportional to the number of revolutions, and its growth varies with dσ. 2 (n) can be represented as:

[0048] dσ 2 (n)=kθ 2 (n)dn

[0049] Where k is a constant.

[0050] To obtain a uniform beam extraction time structure, we have:

[0051]

[0052] Among them, f rev t is the beam cyclotron frequency; ext σ0 is the beam extraction time. 2 is the square of the initial Rayleigh distribution standard deviation; cOnst represents a constant.

[0053] Finally, the functional relationship θ(n) between the excitation sweep angle and the number of revolutions (time) can be obtained as follows:

[0054]

[0055] In summary, the theoretical model of this amplitude modulation curve uses certain assumptions and undergoes some simplifications in its derivation. Therefore, the overall amplitude modulation curve cannot achieve good beam extraction uniformity. It often exhibits a phenomenon where fewer particles are extracted in the early stages, but a large number of particles are extracted in a short period due to the large kick angle at the end, resulting in overall beam inhomogeneity. Furthermore, the difference in the emitted beam also limits the amplitude modulation curve's ability to adjust beam uniformity.

[0056] In view of this, in order to address the problem that the current excitation amplitude modulation curve cannot meet the requirements of beam uniformity under different beam emittance, this invention proposes a beam uniformity improvement method based on the transverse excitation amplitude modulation curve. It introduces a polynomial form of excitation amplitude modulation curve to improve beam extraction uniformity. At the same time, the curve form is more flexible and variable, and it is more in line with the beam distribution in different extraction time loops.

[0057] Figure 3 A flowchart illustrating a method for improving beam uniformity based on a transverse excitation sweep curve according to an embodiment of the present invention is shown.

[0058] like Figure 3 As shown, the beam uniformity improvement method based on the transverse excitation sweep curve according to this embodiment may include steps S1 to S5.

[0059] Step S1: Establish the excitation amplitude modulation curve in the form of a polynomial function and initialize the polynomial coefficients of the excitation amplitude modulation curve.

[0060] In this embodiment of the invention, the polynomial function is a sixth-degree polynomial, and the excitation amplitude modulation curve is initialized as follows:

[0061] θ RF-KO =A1t+A2t 2 +A3t 3 +A4t 4 +A5t 5 +A6t 6 +C

[0062] In the formula, t is the extraction time; θ RF-KO , where is the sweep kick angle of the lateral excitation; A1, A2, ..., A6, C are the polynomial coefficients to be adjusted.

[0063] Step S2: During the beam tuning process of the accelerator, the control program generates and sends out the initial excitation amplitude modulation curve, applies the corresponding voltage value to the transverse excitation plate, records the change information of the number of beam particles during the extraction process in the lead-out beamline or terminal ionization chamber, and feeds the change information back to the control program.

[0064] Step S3: The control program adjusts the polynomial coefficients based on the feedback results of the extracted beam to update the excitation amplitude modulation curve.

[0065] Figure 4 A flowchart illustrating the adjustment of polynomial coefficients according to an embodiment of the present invention is shown.

[0066] like Figure 4 As shown, in this embodiment of the invention, step S3 may further include steps S31 to S32.

[0067] Step S31: Based on the feedback results of the beam uniformity, the control program divides the beam extraction process into multiple extraction time periods.

[0068] Step S32: During different extraction time periods, the slope of the excitation amplitude modulation curve is made to be different and / or the degree of slope change is different.

[0069] In this embodiment of the invention, the multiple lead-out time periods include a lead-out start segment, a lead-out early segment, a lead-out mid-late segment, and a lead-out end segment, wherein:

[0070] In the initial section, a first sweep kick angle is set, and then the first sweep kick angle is reduced to a second sweep kick angle;

[0071] In the initial stage of the excitation amplitude modulation curve, the slope of the curve is made to fluctuate or remain stable within the first preset amplitude range.

[0072] In the later stage of the excitation, the slope of the excitation amplitude curve is gradually increased within the second preset amplitude range;

[0073] In the final stage, the slope of the excitation amplitude curve is gradually increased by a third preset amplitude range, wherein the third preset amplitude range is greater than the second preset amplitude range.

[0074] The embodiments of the present invention propose a polynomial-based transverse excitation amplitude modulation curve form through particle tracking simulation and related calculations, replacing the traditional theoretical amplitude modulation curve.

[0075] Figure 5 The diagram schematically illustrates a theoretical amplitude modulation curve and a polynomial form transverse excitation amplitude modulation curve according to an embodiment of the present invention, wherein (a) is the theoretical amplitude modulation curve and (b) is a polynomial form transverse excitation amplitude modulation curve.

[0076] Specifically, such as Figure 5 The figures show two types of amplitude modulation (AM) curves. The biggest difference is that the slope of the polynomial function form AM curve changes throughout the extraction process, no longer continuously increasing. Based on the different extraction time periods, the beam can be divided into the following four stages:

[0077] (1) Initial stage of extraction: At this time, the beam emittance is close to the area of ​​the stable region. The excitation will first increase the beam emittance with a large kick angle (i.e., the first sweep kick angle) so that the particles reach the boundary of the stable region. Then the excitation kick angle can be reduced (i.e., the first sweep kick angle is reduced to the second sweep kick angle), so that the particles are extracted under the resonance effect of the excitation.

[0078] (2) Leading out the middle and early stages: Since there are still many particle beams in the synchronization loop and a large number of particles at the boundary of the phase stable region, the excitation kick angle is still small and the slope of the curve changes slowly.

[0079] In other words, during the initial stage of the excitation amplitude modulation curve, the slope can be made to fluctuate or remain stable within a first preset amplitude range. This first preset amplitude range is a relatively small upper and lower range, which can be set according to experimental or simulation conditions; the present invention does not impose any specific limitations.

[0080] (3) Extraction of the middle and rear sections: The beam emission decreases and the excitation kick angle gradually increases (that is, the slope gradually increases within the second preset amplitude range), so that the particles near the beam nucleus gradually move to the boundary of the phase stable region and are extracted.

[0081] (4) Leading to the final stage: The number of particles in the ring is the smallest and the emission is the smallest, so a larger excitation kick angle is required. In this stage, the kick angle slope will increase sharply (that is, the slope will gradually increase within the third preset amplitude range).

[0082] The third preset amplitude range is greater than the second preset amplitude range, ensuring that the increase in the final stage of the lead-in is greater than that in the middle and later stages of the lead-in.

[0083] Therefore, compared to the theoretical excitation curve, the slope of the polynomial curve changes more slowly in the middle section of the beam extraction, and the slope does not increase continuously. Simultaneously, the kick angle exhibits a greater increase within a narrower range at the extraction end. This is particularly effective in improving the uniformity of slow extraction of low-emittance beams.

[0084] Step S4: Repeat steps S2 to S3 until the uniformity of the extracted beam reaches the predetermined requirement, then stop the feedback and determine the optimal excitation amplitude modulation curve.

[0085] Step S5: The control program adjusts the beam extraction time structure according to the optimal excitation amplitude modulation curve.

[0086] The embodiments of the present invention provide a scheme to improve the uniformity of the slow-extraction beam in an accelerator. By changing the high-voltage curve waveform of the slow-extraction excitation plate loading, the number of extracted particles in different time loops can be adjusted, thereby improving the uniformity of beam extraction.

[0087] The applicant also conducted simulation verification of the beam uniformity improvement method based on the transverse excitation sweep curve of the present invention.

[0088] Figure 6 The diagram schematically illustrates the extraction beam time structure under the theoretical amplitude modulation curve and the polynomial form transverse excitation amplitude modulation curve according to an embodiment of the present invention, wherein (a) is the extraction beam time structure corresponding to the theoretical amplitude modulation curve, and (b) is the extraction beam time structure corresponding to the polynomial form transverse excitation amplitude modulation curve.

[0089] like Figure 6 The figure shows the simulated beam time structure of a 300 MeV proton beam in a synchrotron ring during a slow extraction of 0.18 s. It can be seen that the macroscopic uniformity of the beam extraction is better under the polynomial form of transverse excitation amplitude modulation curve, while the theoretical amplitude modulation curve has a larger extraction of a large number of particles due to the increased kick angle in the middle and later stages, resulting in poorer beam uniformity.

[0090] Furthermore, by adjusting the polynomial coefficients multiple times, the applicant can determine the optimal excitation amplitude curve.

[0091] For example, the polynomial coefficients of the optimal excitation amplitude modulation curve, with time (in seconds) on the horizontal axis and the excitation kick angle (in mrad) on the vertical axis, can take the following values: A1 = 0.00102, A2 = 0.0823, A3 = 0.1778, A4 = -19.65, A5 = 158.24, A6 = -359.53, C = 0.00044. It should be noted that the polynomial coefficients of the optimal excitation amplitude modulation curve are not necessarily this set of parameters, but are adjusted and varied according to factors such as the type and energy of particles in the actual accelerator operation. This invention does not impose any specific limitations on this.

[0092] Based on the above publicly available information. Figure 7 The schematic diagram illustrates the principle of the method according to an embodiment of the present invention in actual beam tuning.

[0093] like Figure 7 As shown, in the actual accelerator beam tuning process, the control program generates and sends the waveform file of the excitation amplitude modulation curve based on the input initial 6th-order polynomial coefficients. The transverse excitation plate is loaded with the corresponding voltage value for beam extraction. The change in the number of particles in the beam during the entire extraction process is recorded through the ionization chamber placed in the subsequent beamline or terminal, and the data is fed back to the transverse excitation. The control program further reads, analyzes, and adjusts the coefficients, regenerates the waveform file of the excitation amplitude modulation curve, and sends it back for the next slow extraction. This process is repeated iteratively until the extracted beam meets a certain uniformity, at which point the feedback ends, and the 6th-order polynomial coefficients are finally determined.

[0094] Through the embodiments of the present invention, the method mainly uses the feedback signal of the ionization chamber to iteratively iterate the excitation curve coefficients to find the optimal excitation curve under the corresponding emittance. It optimizes the macroscopic uniformity of the extracted beam based on excitation feedback and is simple to operate.

[0095] The above is merely an illustrative example, and the embodiments of the present invention are not limited thereto. For example, in some embodiments, such as Figure 7 As shown, the control program is set within the beam tuning software used in the accelerator's central control room.

[0096] In some embodiments, such as Figure 7 As shown, in step S2, the terminal ionization chamber is placed at the external terminal connected to the accelerator.

[0097] In some embodiments, the method is applied in an accelerator slow-extraction excitation mode, the accelerator including a medical accelerator.

[0098] The embodiments of the present invention aim to further regulate the beam extraction time structure by changing the slow extraction excitation mode of the accelerator, so as to make the number of extracted particles more uniform at different times, which is beneficial to improving the beam quality of the medical accelerator treatment terminal.

[0099] Through the embodiments of the present invention, this method can effectively improve traditional transverse excitation, making the temporal structure of the slow-extracted beam more uniform, improving treatment efficiency. The actual beam tuning process is simple and efficient, without adding any additional components. Furthermore, in actual accelerator operation, the excitation control program only needs to change the polynomial coefficients to generate different excitation curves, enabling more effective adjustment of the extracted beam temporal structure under different emittances.

[0100] Figure 8 A block diagram of an electronic device suitable for implementing a beam uniformity improvement method based on a transverse excitation sweep curve, according to an embodiment of the present invention, is shown schematically.

[0101] like Figure 8 As shown, an electronic device 800 according to an embodiment of the present invention includes a processor 801, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 802 or a program loaded from a storage portion 808 into a random access memory (RAM) 803. The processor 801 may include, for example, a general-purpose microprocessor (e.g., a CPU), an instruction set processor and / or an associated chipset and / or a special-purpose microprocessor (e.g., an application-specific integrated circuit (ASIC)), etc. The processor 801 may also include onboard memory for caching purposes. The processor 801 may include a single processing unit or multiple processing units for performing different actions of the method flow according to an embodiment of the present invention.

[0102] RAM 803 stores various programs and data required for the operation of electronic device 800. Processor 801, ROM 802, and RAM 803 are interconnected via bus 804. Processor 801 executes various operations of the method flow according to embodiments of the present invention by executing programs in ROM 802 and / or RAM 803. It should be noted that the programs may also be stored in one or more memories other than ROM 802 and RAM 803. Processor 801 may also execute various operations of the method flow according to embodiments of the present invention by executing programs stored in said one or more memories.

[0103] According to an embodiment of the present invention, the electronic device 800 may further include an input / output (I / O) interface 805, which is also connected to a bus 804. The electronic device 800 may also include one or more of the following components connected to the I / O interface 805: an input section 806 including a keyboard, mouse, etc.; an output section 807 including a cathode ray tube (CRT), liquid crystal display (LCD), etc., and a speaker, etc.; a storage section 808 including a hard disk, etc.; and a communication section 809 including a network interface card such as a LAN card, modem, etc. The communication section 809 performs communication processing via a network such as the Internet. A drive 810 is also connected to the I / O interface 805 as needed. A removable medium 811, such as a disk, optical disk, magneto-optical disk, semiconductor memory, etc., is installed on the drive 810 as needed so that computer programs read from it can be installed into the storage section 808 as needed.

[0104] The present invention also provides a computer-readable storage medium, which may be included in the device / apparatus / system described in the above embodiments; or it may exist independently and not assembled into the device / apparatus / system. The computer-readable storage medium carries one or more programs, which, when executed, implement the beam uniformity improvement method based on the transverse excitation sweep curve according to embodiments of the present invention.

[0105] According to embodiments of the present invention, a computer-readable storage medium may be a non-volatile computer-readable storage medium, such as including, but not limited to: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In the present invention, a computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. For example, according to embodiments of the present invention, a computer-readable storage medium may include ROM 802 and / or RAM 803 and / or one or more memories other than ROM 802 and RAM 803 described above.

[0106] The accompanying drawings show some block diagrams and / or flowcharts. It should be understood that some blocks or combinations thereof in the block diagrams and / or flowcharts can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that when executed by the processor, these instructions can create means for implementing the functions / operations described in these block diagrams and / or flowcharts.

[0107] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified. Furthermore, the word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0108] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for improving beam uniformity based on transverse excitation sweeping curve, characterized in that, The method comprises: Step S1, establishing an excitation amplitude modulation curve in the form of a polynomial function, initializing polynomial coefficients of the excitation amplitude modulation curve, the polynomial function being a sixth-degree polynomial, and the excitation amplitude modulation curve being initialized as: wherein is the lead time; is the lateral excitation swath kick angle; is the polynomial coefficient to be adjusted; Step S2, during a beam modulation process of an accelerator, a control program generates and issues the initialized excitation amplitude modulation curve, loads corresponding voltage values on transverse excitation plates, records variation information of beam particle numbers in a beam extraction process by an extraction beam line or a terminal ionization chamber, and feeds back the variation information to the control program; Step S3, the control program adjusts the polynomial coefficients according to feedback results of the extraction beam, to update the excitation amplitude modulation curve; Step S4, repeating the steps S2-S3 until a uniformity of the measured extraction beam reaches a predetermined requirement, stopping feedback, and determining an optimal excitation amplitude modulation curve; Step S5, the control program adjusts a beam extraction time structure according to the optimal excitation amplitude modulation curve; The step S3 comprises: Step S31, the control program divides a beam extraction process into multiple extraction time periods according to feedback results of the uniformity of the extraction beam; Step S32, in different extraction time periods, the slope of the excitation amplitude modulation curve is different in size and / or degree of change; The multiple extraction time periods comprise an extraction start period, an extraction middle front period, an extraction middle rear period, and an extraction end period, wherein: In the extraction start period, a first amplitude kick angle is set, and then the first amplitude kick angle is reduced to a second amplitude kick angle; In the extraction middle front period, the slope of the excitation amplitude modulation curve fluctuates in a first preset amplitude range or remains unchanged; In the extraction middle rear period, the slope of the excitation amplitude modulation curve is gradually increased in a second preset amplitude range; In the extraction end period, the slope of the excitation amplitude modulation curve is gradually increased in a third preset amplitude range, and the third preset amplitude range is greater than the second preset amplitude range.

2. The beam uniformity enhancement method based on transverse excitation scanning curve according to claim 1, characterized in that, The control program is contained in beam modulation software used in a central control room of an accelerator.

3. The beam uniformity enhancement method based on transverse excitation scanning curve according to claim 1, characterized in that, The method is applied to a slow extraction excitation working mode of an accelerator, and the accelerator comprises a medical accelerator.

4. The beam uniformity enhancement method based on transverse excitation scanning curve according to claim 1, characterized in that, In the step S2, the terminal ionization chamber is placed at an external terminal connected to the accelerator.

5. An electronic device, comprising: The method comprises: One or more processors; A memory for storing one or more programs, When the one or more programs are executed by the one or more processors, the one or more processors implement the method in any one of claims 1 to 4.

6. A computer-readable storage medium, characterized in that, Executable instructions are stored thereon, and the instructions are executed by a processor to make the processor implement the method in any one of claims 1 to 4.

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