CN-122021219-A - Calculation compensation method for isochronous magnetic field of cyclotron

CN122021219ACN 122021219 ACN122021219 ACN 122021219ACN-122021219-A

Abstract

The invention provides a calculation compensation method of an isochronous magnetic field of a cyclotron, which relates to the technical field of data processing, and the method comprises the steps of carrying out particle tracking by adopting a numerical integration method, adjusting initial parameters of particles by iterative search, and obtaining a closed orbit of charged particles when the position and the deviation between momentum of the particles after one circle of movement and the initial values are in a preset error range; based on the closed orbit, applying radial and axial micro-disturbance to the initial state of the particle, tracking the movement of the particle for multiple circles, recording oscillation data, performing fast Fourier transform analysis on the oscillation data, extracting the radial oscillation frequency and the axial oscillation frequency of the particle, calculating the cyclotron frequency of the particle according to the closed orbit, combining the radial oscillation frequency and the axial oscillation frequency, and generating parameters for evaluating and compensating the isochronous magnetic field of the cyclotron. The invention can effectively improve the running stability and the particle acceleration efficiency of the accelerator.

Inventors

GU LONG
WANG YONGQUAN
Su Xingkang
WANG GUAN
ZHANG SHIXU
QIU JING
CHEN QIJIAN

Assignees

福建睿斯科医疗技术有限公司

Dates

Publication Date: 20260512
Application Date: 20260320

Claims (10)

1. A method for computationally compensating for isochronous magnetic fields in a cyclotron, the method comprising: Step 1, acquiring magnetic field distribution data of a cyclotron, and performing gridding storage and interpolation processing on the magnetic field distribution data to obtain processed magnetic field data; Step 2, establishing a motion equation of the charged particles in the static magnetic field by using the processed magnetic field data, carrying out particle tracking by adopting a numerical integration method, and adjusting initial parameters of the particles by iterative search, so as to obtain a closed orbit of the charged particles when the position and the deviation between the momentum of the particles after one circle of movement and the initial values are in a preset error range; step 3, based on the closed orbit, applying radial and axial micro-disturbance to the initial state of the particles, tracking the multi-circle motion of the particles, recording oscillation data, performing fast Fourier transform analysis on the oscillation data, and extracting the radial oscillation frequency and the axial oscillation frequency of the particles; and 4, calculating the cyclotron frequency of the particles according to the closed orbit, and generating parameters for evaluating and compensating the isochronous magnetic field of the cyclotron by combining the radial oscillation frequency and the axial oscillation frequency.
2. The method for compensating for a cyclotron isochronous magnetic field according to claim 1, wherein the step of obtaining the cyclotron magnetic field distribution data, and performing gridding storage and interpolation processing on the magnetic field distribution data to obtain processed magnetic field data, comprises: based on the original magnetic field distribution data, carrying out grid division in a set coordinate system to obtain discrete magnetic field data points; and carrying out symmetrical processing on the interpolated magnetic field information to obtain processed magnetic field data.
3. The method for compensating for a cyclotron isochronous magnetic field according to claim 2, wherein the method for calculating the magnetic field information at any position in space by interpolation based on the magnetic field data points comprises the steps of: Based on the magnetic field data points, selecting four grid points adjacent to the target position as interpolation reference points, and based on the magnetic field values of the four grid points, obtaining magnetic field components of the target position by bilinear interpolation calculation; Based on the magnetic field component of the target position, expanding the magnetic field data to a complete circumference range according to the multiple rotation symmetrical structure of the cyclotron, and obtaining the processed magnetic field data by carrying out weighted average calculation on the symmetrical azimuth position.
4. A method for compensating for the calculation of an isochronous magnetic field of a cyclotron according to claim 3, wherein the steps of using the processed magnetic field data to establish an equation of motion of charged particles in a static magnetic field, performing particle tracking by a numerical integration method, and adjusting initial parameters of the particles by iterative search, and obtaining a closed orbit of the charged particles when a position and a deviation between a momentum of the particles after one movement and the initial values are within a predetermined error range, comprise: Based on the motion equation, adopting a fourth-order Longge-Kutta method to carry out numerical integration calculation on the motion track of the particles, and setting initial state parameters of the particles, including initial radius, azimuth angle and momentum according to the numerical integration calculation requirement; Tracking the single-circle movement of the particles based on the initial state parameters and the numerical integration method to obtain the position and the momentum after the movement of the particles is finished, and calculating to obtain the position deviation and the momentum deviation; Comparing the position deviation and the momentum deviation with a preset error range to obtain a deviation comparison result, adjusting initial state parameters of particles when the deviation exceeds the preset error range according to the deviation comparison result, and re-performing motion tracking; And obtaining the closed orbit of the charged particles according to the position deviation and the momentum deviation obtained after the re-motion tracking when the position deviation and the momentum deviation are both in a preset error range.
5. The method for compensating for a cyclotron isochronous magnetic field according to claim 4, wherein an equation of motion of charged particles in a static magnetic field is established based on the processed magnetic field data, a fourth-order Longer-Curie-Tata method is used to perform numerical integration calculation on a motion trajectory of particles based on the equation of motion, and initial state parameters of particles including an initial radius, an initial azimuth angle, and an initial momentum are set according to the numerical integration calculation requirement, comprising: The method comprises the steps of processing magnetic field data, establishing a motion equation of charged particles in a static magnetic field according to the processed magnetic field data, selecting a fourth-order Dragon-Kutta method as a numerical value solving method based on the motion equation, and obtaining a time step of numerical value integration according to the calculation requirement of the fourth-order Dragon-Kutta method; Discretizing a particle motion track into a series of time nodes based on time steps, and gradually calculating to obtain a particle motion state result in four stages in each step according to the time nodes; The particle motion state result is weighted and averaged to obtain the particle state of the next time node, tracking calculation is circularly executed until single-circle motion is completed, and the setting rule of the initial state parameter is determined according to the stability requirement of the numerical integration process; and setting the initial momentum of the particles according to the initial radius and the initial azimuth angle to obtain initial state parameters.
6. The method for compensating for the calculation of an isochronous magnetic field for a cyclotron according to claim 5, wherein the method for calculating and compensating for an isochronous magnetic field for a cyclotron according to claim 5, wherein the method for applying a minute disturbance in a radial direction and an axial direction to an initial state of a particle based on a closed orbit, tracking a plurality of movements of the particle and recording oscillation data, performing a fast fourier transform analysis on the oscillation data, and extracting a radial oscillation frequency and an axial oscillation frequency of the particle, comprises: performing multi-circle motion tracking of the particles based on the initial state of the particles to obtain position change data of the particles in the radial direction and the axial direction; the method comprises the steps of carrying out fast Fourier transform based on position change data to generate frequency spectrum distribution of particle oscillation, extracting main peak frequencies of radial and axial oscillation based on the frequency spectrum distribution, and obtaining radial oscillation frequency and axial oscillation frequency of particles based on the main peak frequencies.
7. The method for compensating for the calculation of the isochronous magnetic field of a cyclotron according to claim 6, wherein the performing of a fast fourier transform based on the position change data generates a spectrum distribution of the particle oscillation, extracting a main peak frequency of the radial and axial oscillation based on the spectrum distribution, and obtaining the radial oscillation frequency and the axial oscillation frequency of the particle based on the main peak frequency, comprises: Performing a fast fourier transform calculation based on the radial and axial position change data, generating a frequency component distribution of the particle oscillation; Based on the frequency component distribution, identifying the frequency component corresponding to the highest amplitude in the radial oscillation frequency spectrum to obtain the radial oscillation frequency of the particles, and based on the frequency component distribution, identifying the frequency component corresponding to the highest amplitude in the axial oscillation frequency spectrum to obtain the axial oscillation frequency of the particles.
8. The method of claim 7, wherein calculating the cyclotron isochronous magnetic field based on the closed orbit calculates the cyclotron frequency of the particles, and wherein generating parameters for evaluating and compensating the cyclotron isochronous magnetic field in combination with the radial oscillation frequency and the axial oscillation frequency comprises: calculating the time required by a single particle motion circle based on the closed orbit to obtain the convolution period of the particles; Based on the comparison of the convolution frequency and the theoretical isochronal frequency, obtaining a magnetic field isochronal deviation parameter, and based on the radial oscillation frequency and the axial oscillation frequency, calculating a beam hydrodynamic stability parameter; Based on the magnetic field isochronous bias parameter and the beam hydrodynamic stability parameter, a parameter is generated for evaluating and compensating for the cyclotron isochronous magnetic field.
9. A computing device, comprising: one or more processors; Storage means for storing one or more programs which when executed by the one or more processors cause the one or more processors to implement the method of any of claims 1 to 8.
10. A computer readable storage medium, characterized in that the computer readable storage medium has stored therein a program which, when executed by a processor, implements the method according to any of claims 1 to 8.

Description

Calculation compensation method for isochronous magnetic field of cyclotron Technical Field The invention relates to the technical field of data processing, in particular to a calculation compensation method of an isochronous magnetic field of a cyclotron. Background In the design and optimization of isochronous cyclotrons, accurate modeling and isochronous verification of magnetic fields are key links, some isochronous magnetic field calculation methods commonly used in engineering at present can face challenges in determining initial conditions, for example, some existing methods solve closed orbits of charged particles based on simplified orbit models (such as circular orbit approximation), such methods can generally meet requirements in the case of relatively smooth magnetic field distribution and small deviation of particle orbits, however, in practical accelerator design, the actual orbit shape of particle motion can be relatively complex, especially for magnetic fields with strong focusing sector magnetic poles or high flutter characteristics. Under the condition, the initial assumption based on the simplified model may deviate from the actual condition, so that errors can occur in the calculation of the closed orbit, or the problem of poor convergence is faced in the iterative solving process, which limits the applicability of the method under the complex magnetic field structure to a certain extent and also influences the calculation accuracy of key kinetic parameters such as the follow-up convolution frequency, oscillation characteristics and the like. Disclosure of Invention The invention aims to solve the technical problem of providing a calculation compensation method for an isochronous magnetic field of a cyclotron, which can effectively improve the running stability and the particle acceleration efficiency of the accelerator. In order to solve the technical problems, the technical scheme of the invention is as follows: in a first aspect, a method of computing compensation of a cyclotron isochronous magnetic field, the method comprising: Step 1, acquiring magnetic field distribution data of a cyclotron, and performing gridding storage and interpolation processing on the magnetic field distribution data to obtain processed magnetic field data; Step 2, establishing a motion equation of the charged particles in the static magnetic field by using the processed magnetic field data, carrying out particle tracking by adopting a numerical integration method, and adjusting initial parameters of the particles by iterative search, so as to obtain a closed orbit of the charged particles when the position and the deviation between the momentum of the particles after one circle of movement and the initial values are in a preset error range; step 3, based on the closed orbit, applying radial and axial micro-disturbance to the initial state of the particles, tracking the multi-circle motion of the particles, recording oscillation data, performing fast Fourier transform analysis on the oscillation data, and extracting the radial oscillation frequency and the axial oscillation frequency of the particles; and 4, calculating the cyclotron frequency of the particles according to the closed orbit, and generating parameters for evaluating and compensating the isochronous magnetic field of the cyclotron by combining the radial oscillation frequency and the axial oscillation frequency. In a second aspect, a computing device includes: one or more processors; And a storage means for storing one or more programs that, when executed by the one or more processors, cause the one or more processors to implement the method. In a third aspect, a computer readable storage medium has a program stored therein, which when executed by a processor, implements the method. The scheme of the invention at least comprises the following beneficial effects: The method comprises the steps of restraining initial parameters through physical characteristics of particle motion, combining rules that a closed orbit is located in a magnetic field intensity maximum area and radial momentum is zero, reducing the searching range of the initial parameters, dynamically adjusting parameters based on deviation feedback, such as adjusting the initial radius according to position deviation, fine adjusting the initial momentum according to momentum deviation, reducing iteration times, improving solving efficiency of the closed orbit, automatically introducing influence of magnetic field nonlinearity on oscillation through multi-circle actual track tracking, and enabling a calculation result of oscillation frequency to be more fit with an actual magnetic field environment without additionally establishing a nonlinear correction model, and improving calculation accuracy. Drawings Fig. 1 is a flowchart of a method for calculating and compensating an isochronous magnetic field of a cyclotron according to an embodiment of the present invention. FIG. 2 is a schem