A method, device and electronic equipment for optimizing magnetic field of cyclotron main magnet

Abstract

The present invention provides a method, device and electronic equipment for optimizing the magnetic field of a cyclotron main magnet, and relates to the technical field of particle accelerators. A shim block is arranged on the pole face of the main magnet, and the method includes: determining the structural parameters of the pole face, and determining the structural parameters of the shim block based on the structural parameters of the pole face; dividing the pole face into at least two position areas according to the structural parameters of the shim block; determining the magnetic field variation generated by a single shim block in different position areas for each magnetic field area; determining the first current magnetic field of the main magnet and the theoretical magnetic field of the main magnet, and determining the magnetic field difference of each magnetic field area based on the first current magnetic field and the theoretical magnetic field; wherein the magnetic field area includes the position area and the central opening area of ​​the pole face; determining the number of shims set on each position area based on the magnetic field difference and the magnetic field variation, optimizing the isochronism of the magnetic field of the cyclotron main magnet, and improving the accuracy of the magnetic field distribution.

Description

Technical Field

[0001] The present invention relates to the technical field of particle accelerators, and in particular to a method, a device and an electronic device for optimizing the magnetic field of a cyclotron main magnet. Background Art

[0002] Medical isotopes are widely used in the fields of medical diagnosis and tumor treatment, especially 211 At and 225 Ac and other therapeutic isotopes for clinical diagnosis and treatment. Therapeutic isotopes and other medical isotopes can be produced based on high-current compact cyclotrons to increase the production and supply of therapeutic isotopes and other medical isotopes to meet the growing medical needs in China.

[0003] In the process of producing therapeutic isotopes and other medical isotopes by high-current compact cyclotron, the cyclotron is the core equipment of the production plan. It adopts a superconducting high-current design. During the particle acceleration process, if the particles enter the dangerous resonance area, it will cause instability in particle acceleration, thereby reducing the production efficiency of therapeutic isotopes and other medical isotopes, and even making it impossible to produce therapeutic isotopes and other medical isotopes normally.

[0004] In order to prevent particles from entering dangerous resonance areas, the magnetic field distribution of the cyclotron needs to change synchronously with the particle energy, which requires precise electromagnetic field configuration to ensure high-precision magnetic field distribution. However, the current electromagnetic field configuration method cannot meet the accuracy requirements of the magnetic field distribution. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a method, device and electronic equipment for optimizing the magnetic field of a cyclotron main magnet.

[0006] The present invention provides a method for optimizing the magnetic field of a cyclotron accelerator main magnet, wherein a shim block is arranged on the magnetic pole surface of the main magnet, comprising:

[0007] Determine the structural parameters of the magnetic pole surface, and determine the structural parameters of the shim block based on the structural parameters of the magnetic pole surface;

[0008] Dividing the magnetic pole surface into at least two position areas according to the structural parameters of the shim block;

[0009] Determine the magnetic field variation amount generated by a single shim block in different position areas for each magnetic field area; determine the first current magnetic field of the main magnet and the theoretical magnetic field of the main magnet, and determine the magnetic field difference amount of each magnetic field area based on the first current magnetic field and the theoretical magnetic field; wherein the magnetic field area includes the position area and the central opening area of ​​the magnetic pole face;

[0010] The number of the shim blocks to be arranged in each of the position areas is determined based on the magnetic field difference and the magnetic field variation, so as to optimize the isochronism of the magnetic field of the cyclotron main magnet.

[0011] According to a method for optimizing the magnetic field of a cyclotron main magnet provided by the present invention, the regional magnetic field variation of the magnetic field region is obtained by linearly superimposing the magnetic field variation generated by the shim blocks arranged on the pole faces of the magnetic poles in the magnetic field region;

[0012] Determining the number of shimming blocks to be set in each of the position areas based on the magnetic field difference and the magnetic field variation specifically includes:

[0013] Based on the difference between the magnetic field difference amount in each magnetic field region and the magnetic field variation amount in the corresponding region, multiple groups of arrangements of the shim blocks on the magnetic pole surface are obtained; each group of arrangements is the first design quantity of the shim blocks on each position region;

[0014] The arrangement in which the total number of the shim blocks arranged on the pole faces of the magnetic poles is the smallest among the multiple groups of arrangements is determined, and the number of the shim blocks set in each of the position areas is obtained.

[0015] According to a method for optimizing the magnetic field of a cyclotron main magnet provided by the present invention, determining the magnetic field variation generated by a single shim block in different position areas for each magnetic field area specifically includes:

[0016] Establishing a finite element model of the cyclotron main magnet, analyzing the finite element model to determine the simulated magnetic field variation generated by a single shim block in different position areas for each magnetic field area; determining the theoretical magnetic field variation generated by a single shim block in different position areas for each magnetic field area;

[0017] The mean square error between the theoretical magnetic field change and the simulated magnetic field change is calculated, and the mean square error is minimized to adjust the simulated magnetic field change generated by a single shim block in each magnetic field region, and obtain the magnetic field change generated by a single shim block in each magnetic field region at different position areas.

[0018] According to a method for optimizing the magnetic field of a cyclotron main magnet provided by the present invention, before obtaining the number of shimming blocks to be set in each position area, the method further comprises:

[0019] Obtaining a second design quantity of the shim blocks to be set on each of the position areas;

[0020] The quantity difference of the shim blocks in adjacent position areas is calculated, and the quantity difference is smoothed to adjust the second design quantity of the shim blocks set in each position area.

[0021] According to a method for optimizing the magnetic field of a cyclotron main magnet provided by the present invention, after smoothing the quantity difference, the method further includes:

[0022] Obtaining a third design quantity of the shim blocks to be arranged on each of the magnetic field regions;

[0023] Determine the regional magnetic field variation of each of the magnetic field regions according to a third designed number of shim blocks arranged in each of the position regions;

[0024] When the difference between the regional magnetic field variation and the corresponding magnetic field difference is within a preset range, the third design quantity is determined as the quantity of the shim blocks to be set in each of the position areas.

[0025] According to a method for optimizing the magnetic field of a cyclotron main magnet provided by the present invention, after determining the regional magnetic field variation of each magnetic field region according to the third design number of shim blocks set in each position region, the method further comprises:

[0026] When the difference between the regional magnetic field variation and the corresponding magnetic field difference is outside the preset range, repeat the above steps of determining the number of patch blocks to be set in each position area until the difference between the regional magnetic field variation and the corresponding magnetic field difference is within the preset range.

[0027] According to a method for optimizing the magnetic field of a cyclotron main magnet provided by the present invention, the structural parameters of the shim block include the shim block width, and the structural parameters of the magnetic pole surface include the magnetic pole surface width;

[0028] The magnetic pole surface is divided into at least two position areas according to the structural parameters of the shim block, specifically including:

[0029] Determining the number of position areas on the pole face of the magnetic pole based on the ratio of the pole face width to the shim block width;

[0030] The number of position areas is divided radially from one side of the magnetic pole surface toward the other side according to the width of the shim block.

[0031] According to a method for optimizing the magnetic field of a cyclotron main magnet provided by the present invention, determining the magnetic field variation generated by a single shim block in different position areas for each magnetic field area specifically includes:

[0032] determining the original magnetic field of each of the magnetic field regions;

[0033] After determining the target position area of ​​the magnetic pole surface of the main magnet and arranging a single shim block, a second current magnetic field of each magnetic field area;

[0034] Determine the magnetic field change amount generated by a single shim block in each magnetic field area in the target position area according to the difference between the second current magnetic field and the original magnetic field;

[0035] Repeat the step of determining the amount of magnetic field change generated by a single shim block in different target position areas for each magnetic field area to determine the amount of magnetic field change generated by a single shim block in different position areas for each magnetic field area.

[0036] The present invention also provides a magnetic field optimization device for a cyclotron accelerator main magnet, wherein a shim block is arranged on the magnetic pole surface of the main magnet, comprising:

[0037] A parameter determination module, used for determining the structural parameters of the magnetic pole surface, and determining the structural parameters of the shim block based on the structural parameters of the magnetic pole surface;

[0038] A region division module, used for dividing the magnetic pole surface into at least two position regions according to the structural parameters of the shim block;

[0039] A magnetic field determination module, used to determine the magnetic field variation amount generated by a single shim block in different position areas for each magnetic field area; determine the first current magnetic field of the main magnet and the theoretical magnetic field of the main magnet, and determine the magnetic field difference amount of each magnetic field area based on the first current magnetic field and the theoretical magnetic field; wherein the magnetic field area includes the position area and the central opening area of ​​the magnetic pole face;

[0040] The quantity determination module is used to determine the quantity of the shimming blocks to be set in each of the position areas based on the magnetic field difference and the magnetic field variation, so as to optimize the isochronism of the magnetic field of the cyclotron main magnet.

[0041] The present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the magnetic field optimization method for the main magnet of a cyclotron accelerator as described above is implemented.

[0042] The magnetic field optimization method, device and electronic equipment of the cyclotron main magnet provided by the present invention determine the structural parameters of the shim block through the structural parameters of the magnetic pole surface, divide the magnetic pole surface into position areas according to the structural parameters of the shim block, determine the magnetic field change amount generated by a single shim block in different position areas for each magnetic field area, and the difference amount between the first current magnetic field of the main magnet and the theoretical magnetic field in each magnetic field area, and determine the number of shim blocks to be set in each position area based on the magnetic field difference amount and the magnetic field change amount, so that the first current magnetic field of the main magnet gradually approaches the theoretical magnetic field, which can improve the accuracy of the magnetic field of the main magnet and optimize the isochronism of the magnetic field of the cyclotron main magnet. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0044] Figure 1 This is one of the flow charts of the magnetic field optimization method of the cyclotron main magnet provided by the present invention.

[0045] Figure 2 It is a structural schematic diagram of the main magnet magnetic pole surface of the magnetic field optimization method of the cyclotron main magnet provided by the present invention.

[0046] Figure 3 It is a partial schematic diagram of the central area of ​​the magnetic field optimization method of the cyclotron main magnet provided by the present invention.

[0047] Figure 4 This is the second flow chart of the magnetic field optimization method of the cyclotron main magnet provided by the present invention.

[0048] Figure 5 It is a structural schematic diagram of the magnetic field optimization device of the cyclotron main magnet provided by the present invention.

[0049] Figure 6 It is a structural schematic diagram of the electronic device provided by the present invention. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0051] Combine the following Figure 1-Figure 6 The present invention describes a method, device and electronic equipment for optimizing the magnetic field of a cyclotron main magnet.

[0052] Figure 1 is one of the flow diagrams of the magnetic field optimization method of the cyclotron main magnet provided by the present invention, wherein a shim block is arranged on the magnetic pole surface of the main magnet, such as Figure 1 As shown, the method includes:

[0053] Step 101: Determine the structural parameters of the magnetic pole surface, and determine the structural parameters of the shim block based on the structural parameters of the magnetic pole surface.

[0054] The main magnet refers to the magnet in the central area of ​​the cyclotron that is used to provide a uniform and stable magnetic field to keep the particles synchronized with the specified phase of the high-frequency electric field during the acceleration process. The pole face refers to the working surface of the pole of the cyclotron main magnet, which faces the area where the particle movement track is located.

[0055] like Figure 2 As shown, the shim block can also be called a cutting block, a compensation magnet, etc., and refers to a magnet used to be arranged on the pole face of the main magnet to fine-tune the magnetic field generated by the main magnet. Exemplarily, the material of the shim block can be the same as that of the main magnet. After the shim block is arranged on the pole face of the main magnet, the magnetic field generated by the main magnet can present a preset gradient change from the center to the edge, so as to maintain the synchronization of the particles with the specified phase of the high-frequency electric field during the acceleration process.

[0056] The shim blocks are stacked and arranged on the pole faces of the main magnet, and the overall thickness of the shim blocks in each position area can be adjusted by adjusting the number of shim blocks arranged in each position area.

[0057] Structural parameters refer to parameters such as width, thickness and shape. For example, after determining the structural parameters of the pole face, the width of a single shim block can be determined according to a certain ratio based on the width of the pole face, the thickness of a single shim block can be determined according to a certain ratio based on the thickness of the pole face, and the shape of a single shim block can be determined based on the shape of the pole face, thereby determining the structural parameters of the shim block.

[0058] Step 102: Divide the magnetic pole surface into at least two position areas according to the structural parameters of the shim block.

[0059] The position area refers to the area for arranging the shim block. For example, the magnetic pole surface can be divided into a plurality of position areas from the center to the edge according to the structural parameters of the shim block. The specific number of position areas can be determined according to the uniformity and stability of the magnetic field provided by the main magnet as required, and no further limitation is made here.

[0060] Step 103, determine the magnetic field change amount generated by a single shim block in different position areas for each of the magnetic field areas; determine the first current magnetic field of the main magnet and the theoretical magnetic field of the main magnet, and determine the magnetic field difference amount of each of the magnetic field areas based on the first current magnetic field and the theoretical magnetic field; wherein the magnetic field area includes the position area and the central opening area of ​​the magnetic pole face.

[0061] The magnetic field variation is used to characterize the magnetic field variation of a magnetic field region before and after the placement of a single shim block. The first current magnetic field refers to the magnetic field distribution before the shim block is placed on the magnetic pole surface of the main magnet. It can be measured and calculated based on magnetometers, nuclear magnetic resonance, etc. The theoretical magnetic field refers to the magnetic field distribution required to determine the synchronization of particles with the specified phase of the high-frequency electric field during the acceleration process, which can be determined based on relevant physical theory calculations.

[0062] The magnetic field difference is used to characterize the similarity between the first current magnetic field and the theoretical magnetic field. The magnetic field difference can be the difference between the first current magnetic field and the theoretical magnetic field, or can be the ratio between the first current magnetic field and the theoretical magnetic field.

[0063] Exemplarily, the magnetic pole surface can be divided into a first position area and a second position area, and the amount of magnetic field change generated by a single shim block in the first position area with respect to the first position area, the amount of magnetic field change generated by a single shim block in the first position area with respect to the second position area, and the amount of magnetic field change generated by a single shim block in the first position area with respect to the central opening area of ​​the magnetic pole surface can be determined; the amount of magnetic field change generated by a single shim block in the second position area with respect to the first position area, the amount of magnetic field change generated by a single shim block in the second position area with respect to the second position area, and the amount of magnetic field change generated by a single shim block in the second position area with respect to the central opening area of ​​the magnetic pole surface can be determined.

[0064] Step 104: Determine the number of shim blocks to be set in each position area based on the magnetic field difference and the magnetic field variation, and optimize the isochronism of the magnetic field of the cyclotron main magnet.

[0065] Isochronism means that in the magnetic field of the cyclotron main magnet, the time required for particles to complete a period of motion on orbits of different radii remains constant. In other words, the particle's motion period is independent of the orbital radius of the particle's motion.

[0066] Exemplarily, after arranging different numbers of shim blocks on the pole faces of the main magnet, the change in the magnetic field difference in each magnetic field area can be simulated, and the number of shim blocks to be set in each position area can be determined by minimizing the overall magnetic field difference of the main magnet.

[0067] The magnetic field optimization method of the cyclotron main magnet provided in the embodiment of the present invention determines the structural parameters of the shim block through the structural parameters of the magnetic pole surface, divides the magnetic pole surface into position areas according to the structural parameters of the shim block, determines the magnetic field change amount generated by a single shim block in different position areas for each magnetic field area, and the difference amount between the first current magnetic field of the main magnet and the theoretical magnetic field in each magnetic field area, and determines the number of shim blocks to be set in each position area based on the magnetic field difference amount and the magnetic field change amount, so that the first current magnetic field of the main magnet gradually approaches the theoretical magnetic field, which can improve the accuracy of the magnetic field of the main magnet and optimize the isochronism of the magnetic field of the cyclotron main magnet.

[0068] Based on the above embodiment, the regional magnetic field variation of the magnetic field region is obtained by linearly superimposing the magnetic field variation generated by the shim blocks arranged on the pole faces of the magnetic poles in the magnetic field region.

[0069] It can be expressed by the following formula:

[0070]

[0071] in, is the regional magnetic field variation of the nth magnetic field region, is the magnetic field change generated by a single shim block in the mth position area in the nth magnetic field area, is the number of padding blocks in the mth location area.

[0072] It can be understood that the magnetic field variation generated by a plurality of shims arranged in a position area in a magnetic field area is also linearly superimposed.

[0073] Determining the number of shimming blocks to be set in each of the position areas based on the magnetic field difference and the magnetic field variation specifically includes:

[0074] Based on the difference between the magnetic field difference amount in each magnetic field region and the magnetic field variation amount in the corresponding region, multiple groups of arrangements of the shim blocks on the magnetic pole surface are obtained; each group of arrangements is the first design quantity of the shim blocks on each position region;

[0075] The arrangement in which the total number of the shim blocks arranged on the pole faces of the magnetic poles is the smallest among the multiple groups of arrangements is determined, and the number of the shim blocks set in each of the position areas is obtained.

[0076] The first design quantity refers to the quantity of shim blocks arranged in each position area in each group of arrangements that can meet the requirement of the difference between the magnetic field difference in each magnetic field area and the magnetic field variation in the corresponding area.

[0077] Exemplarily, based on the formula of the regional magnetic field variation of the above magnetic field region, the expression matrix of the magnetic field variation of the magnetic pole surface of the main magnet can be converted as follows:

[0078]

[0079] On the basis of determining the magnetic field difference amount of each magnetic field region, the number of shimming blocks in each position region can be adjusted in combination with the expression matrix of the regional magnetic field variation amount of each magnetic field region, so that the first current magnetic field of the main magnet approaches the theoretical magnetic field of the main magnet. Exemplarily, when the overall difference between the first current magnetic field of the main magnet and the theoretical magnetic field of the main magnet is within a preset threshold range, it can be considered that the first current magnetic field of the main magnet meets the design requirements. It can be understood that there are multiple groups of first design numbers of shimming blocks on each of the position regions, which can make the overall difference between the first current magnetic field and the theoretical magnetic field of the main magnet within a preset threshold range.

[0080] in, Indicates the magnetic field variation generated by a single shim block in the first position area in the first, second, ..., nth magnetic field areas on the magnetic pole surface; It represents the magnetic field change generated by a single shim block in the second position area in the 1st, 2nd, ..., nth magnetic field areas on the pole face. The whole can be called the contribution matrix of the shim block to the magnetic field.

[0081] The arrangement with the smallest total number of shimming blocks arranged on the pole faces of the magnetic poles in the group arrangement can be determined by the following formula, and the number of shimming blocks arranged on each position area can be obtained:

[0082]

[0083] in, A vector of the number of shim blocks describing the number of shim blocks to be set for each location region, To describe the contribution matrix of the shim block to the magnetic field, is the target vector describing the error between the simulated magnetic field change of the patch block and the theoretical magnetic field change, for The transposed matrix is ​​obtained by swapping the rows and columns.

[0084] In this embodiment, based on the difference between the magnetic field difference in each magnetic field area and the magnetic field change in the corresponding area, the manner of arranging the shim blocks on the pole surface is adjusted so that the first current magnetic field of the main magnet gradually approaches the theoretical magnetic field, thereby determining multiple groups of arrangements of the shim blocks on the pole surface, minimizing the multiple groups of arrangements, and obtaining an arrangement with the least total number of shim blocks, which can optimize the magnetic field distribution with the lowest resource consumption, and at the same time reduce the total number of shim blocks can reduce the manufacturing complexity of the main magnet.

[0085] Based on any of the above embodiments, determining the magnetic field variation amount generated by a single shim block in different position areas for each magnetic field area specifically includes:

[0086] Establishing a finite element model of the cyclotron main magnet, analyzing the finite element model to determine the simulated magnetic field variation generated by a single shim block in different position areas for each magnetic field area; determining the theoretical magnetic field variation generated by a single shim block in different position areas for each magnetic field area;

[0087] The mean square error between the theoretical magnetic field change and the simulated magnetic field change is calculated, and the mean square error is minimized to adjust the simulated magnetic field change generated by a single shim block in each magnetic field region, and obtain the magnetic field change generated by a single shim block in each magnetic field region at different position areas.

[0088] For example, a finite element model of the cyclotron main magnet can be established in the finite element analysis software Opera21 and analyzed to determine the simulated magnetic field change generated by a single shim block in different position areas for each magnetic field area, and the theoretical magnetic field change generated by a single shim block in different position areas for each magnetic field area can be determined by theoretical calculation.

[0089] The mean square error between the theoretical magnetic field variation and the simulated magnetic field variation can be calculated by the following formula:

[0090]

[0091] in, is the mean square error between the theoretical magnetic field variation and the simulated magnetic field variation, is the number of regions in the magnetic field region, is the simulated magnetic field change in the ith magnetic field region, is the theoretical magnetic field change in the i-th magnetic field region.

[0092] In this embodiment, while reflecting the nonlinear effects of the coupling effect of the electromagnetic field, the shape, size, and position of the shim block on the pole surface of the main magnet on the local and overall distribution of the magnetic field, the error between the simulated magnetic field change and the theoretical magnetic field change can be formally expressed by the mean square error, providing an optimized reference direction, combined with minimizing the mean square error, to improve the magnetic field accuracy of the optimized cyclotron main magnet.

[0093] As mentioned above, the shims are stacked and arranged on the pole surface of the main magnet. If the difference in the number of shims in adjacent position areas is too large, it will cause drastic height fluctuations between adjacent areas on the pole surface, resulting in magnetic field distortion, making it difficult for the measured data to reflect the actual distribution, increasing the complexity of magnetic field calibration, and increasing the difficulty of mechanical implementation.

[0094] To solve the above problem, based on any of the above embodiments, before obtaining the number of the shimming blocks set in each of the position areas, the method further includes:

[0095] Obtaining a second design quantity of the shim blocks to be set on each of the position areas;

[0096] The quantity difference of the shim blocks in adjacent position areas is calculated, and the quantity difference is smoothed to adjust the second design quantity of the shim blocks set in each position area.

[0097] The second design quantity refers to the number of shim blocks set in each position area after optimizing the simulated magnetic field variation generated by a single shim block in different position areas for each magnetic field area.

[0098] For example, after smoothing the quantity difference, a new quantity of shimming blocks set in each position area can be obtained, and the second design quantity in each position area can be adjusted based on the new quantity. For example, if the new quantity of shimming blocks in one position area is higher than the second design quantity, a corresponding number of shimming blocks is added, and if the new quantity of shimming blocks in another position area is lower than the second design quantity, a corresponding number of shimming blocks is extracted, and if the new quantity of shimming blocks in another position area is equal to the second design quantity, no adjustment is made.

[0099] Exemplarily, the quantity difference may be smoothed by neighbor regularization using the following formula:

[0100]

[0101] in, is the quantity difference, is the regularization parameter, Set the number of padding blocks for the jth location area, is the area number of the location area.

[0102] In this embodiment, the height fluctuation between adjacent position areas is formally expressed by the quantitative difference. By minimizing the quantitative difference, the height between adjacent position areas can be made as small as possible, thereby improving the smoothness between adjacent position areas after shim blocks are set on the pole faces of the magnetic poles, reducing the complexity of the magnetic field calibration, and improving the operability of the mechanical implementation.

[0103] In one embodiment, the mean square error minimization process between the theoretical magnetic field variation and the simulated magnetic field variation and the minimization process of the difference in the number of shim blocks in adjacent position areas may be performed simultaneously.

[0104] The mean square error between the theoretical magnetic field variation and the simulated magnetic field variation, as well as the difference in the number of shim blocks in adjacent position areas, can be reflected based on the following formula:

[0105]

[0106] in, is the magnetic field loss function of the main magnet.

[0107] In this embodiment, by minimizing the magnetic field loss function of the main magnet, the error between the simulated magnetic field change and the theoretical magnetic field change, as well as the difference in the number of shim blocks in adjacent position areas can be balanced, thereby satisfying the accuracy of magnetic field optimization and the operability of mechanical implementation as a whole, making the magnetic pole surface of the main magnet more stable and effective in practical applications.

[0108] Based on any of the above embodiments, after smoothing the quantity difference, the method further includes:

[0109] Obtaining a third design quantity of the shim blocks to be set on each of the position areas;

[0110] Determine the regional magnetic field variation of each of the magnetic field regions according to a third designed number of shim blocks arranged in each of the position regions;

[0111] When the difference between the regional magnetic field variation and the corresponding magnetic field difference is within a preset range, the third design quantity is determined as the quantity of the shim blocks to be set in each of the position areas.

[0112] The third design quantity refers to the number of shim blocks set in each magnetic field area after optimizing the simulated magnetic field change generated by a single shim block in different position areas for each magnetic field area and the difference in the number of shim blocks in adjacent position areas.

[0113] Based on any of the above embodiments, after determining the regional magnetic field variation of each of the magnetic field regions according to the third designed number of shim blocks set in each of the position regions, the method further includes:

[0114] When the difference between the regional magnetic field variation and the corresponding magnetic field difference is outside the preset range, repeat the above steps of determining the number of patch blocks to be set in each position area until the difference between the regional magnetic field variation and the corresponding magnetic field difference is within the preset range.

[0115] It can be understood that the specific range of the preset range can be determined according to the magnetic field accuracy required to be provided by the main magnet, and the embodiment of the present invention does not specifically limit this.

[0116] Compared with the traditional empirical calculation method, in this embodiment, on the basis of optimizing the simulated magnetic field change generated by a single shim block in different position areas for each magnetic field area, as well as the difference in the number of shim blocks in adjacent position areas, the setting scheme of the shim blocks on the pole faces of the main magnet is repeatedly iterated and improved, so that the current magnetic field of the main magnet gradually approaches the theoretical magnetic field until the adjusted magnetic field isochronism meets the physical design requirements of the main magnet, thereby improving the accuracy of the magnetic field design.

[0117] Based on any of the above embodiments, the structural parameters of the shim block include the shim block width, and the structural parameters of the magnetic pole surface include the magnetic pole surface width.

[0118] In this embodiment, the width of each shim block is the same. The width of the shim block can be set according to the design requirements, and the embodiment of the present invention does not specifically limit this. For example, when the width of the magnetic pole face is 250mm, the width of the shim block can be determined to be 10mm.

[0119] Further, such as Figure 3 As shown, the central section of the cyclotron main magnet, such as the 0-10 mm section, generally needs to be opened to install other systems. Therefore, shims are generally not arranged in the central section of the main magnet, but the shims generate magnetic field changes in the central section of the main magnet. Exemplarily, the magnetic field area may include the position area corresponding to the 0-10 mm section and the 25 position areas divided on the pole face of the magnetic pole; the position area does not include the area corresponding to the 0-10 mm section, but only includes the 25 position areas divided on the pole face of the magnetic pole. .

[0120] The magnetic pole face is divided into at least two position areas according to the structural parameters of the shim block, specifically including: determining the number of position areas on the magnetic pole face based on the ratio of the width of the magnetic pole face to the width of the shim block; dividing the number of position areas radially from one side of the magnetic pole face to the other side according to the width of the shim block. In this way, the width of the shim block can be made the same as the width of the position area, avoiding the gap between the shim blocks after the shim blocks are placed on the adjacent position areas, resulting in local magnetic field distortion, thereby improving the uniformity of magnetic field distribution and facilitating the operability of mechanical realization such as processing and installation.

[0121] The pole face width of the magnetic pole refers to the radial width of the pole face of the magnetic pole. Exemplarily, the shape of the shim block and the shape of the position area on the pole face of the magnetic pole may also be the same.

[0122] Based on any of the above embodiments, determining the magnetic field variation amount generated by a single shim block in different position areas for each magnetic field area specifically includes:

[0123] determining the original magnetic field of each of the magnetic field regions;

[0124] After determining the target position area of ​​the magnetic pole surface of the main magnet and arranging a single shim block, a second current magnetic field of each magnetic field area;

[0125] Determine the magnetic field change amount generated by a single shim block in each magnetic field area in the target position area according to the difference between the second current magnetic field and the original magnetic field;

[0126] Repeat the step of determining the amount of magnetic field change generated by a single shim block in different target position areas for each magnetic field area to determine the amount of magnetic field change generated by a single shim block in different position areas for each magnetic field area.

[0127] Exemplarily, each position area may be numbered 1, 2, ..., m from one side of the magnetic pole surface to the other side. The magnetic field distribution when no shim block is set on the magnetic pole surface of the main magnet may be obtained by means of a magnetometer, nuclear magnetic resonance, etc., to determine the original magnetic field of each magnetic field area; a single shim block is sequentially arranged in the first position area, the magnetic field distribution is simulated and calculated, and the second current magnetic field of each magnetic field area is determined to obtain the magnetic field variation generated by the single shim block in the first position area in each magnetic field area; a single shim block is arranged in the second position area, the magnetic field distribution is simulated and calculated, and the second current magnetic field of each magnetic field area is determined to obtain the magnetic field variation generated by the single shim block in the second position area in each magnetic field area; until a single shim block is arranged in the mth position area, the magnetic field distribution is simulated and calculated, and the second current magnetic field of each magnetic field area is determined to obtain the magnetic field variation generated by the single shim block in the mth position area in each magnetic field area.

[0128] Figure 4 is a schematic diagram of the architecture of the data query method provided by the present invention, such as Figure 4 As shown, in order to specifically illustrate the function of the magnetic field optimization method for the cyclotron main magnet provided by this embodiment, a specific example is provided below.

[0129] The structural parameters of the shim block include the shim block width, and the structural parameters of the magnetic pole face include the magnetic pole face width.

[0130] A method for optimizing the magnetic field of a cyclotron main magnet, comprising:

[0131] Determine the number of position areas on the pole face of the magnetic pole based on the ratio of the width of the pole face of the magnetic pole to the width of the shim block; divide the number of position areas radially from one side of the pole face of the magnetic pole toward the other side according to the width of the shim block;

[0132] Determine the original magnetic field of each magnetic field region; determine the second current magnetic field of each magnetic field region after a single shim block is arranged in the target position region of the magnetic pole face of the main magnet; determine the magnetic field change amount generated by the single shim block in the target position region for each magnetic field region based on the difference between the second current magnetic field and the original magnetic field; repeat the steps of determining the magnetic field change amount generated by the single shim block in different target position regions for each magnetic field region, and determine the magnetic field change amount generated by the single shim block in different position regions for each magnetic field region;

[0133] Determine a first current magnetic field of the main magnet and a theoretical magnetic field of the main magnet, and determine a magnetic field difference amount of each magnetic field region based on the first current magnetic field and the theoretical magnetic field;

[0134] Based on the difference between the magnetic field difference amount in each magnetic field area and the magnetic field change amount in the corresponding area, multiple groups of arrangements of shimming blocks arranged on the pole surface of the magnetic pole are obtained; each group of arrangements is a first design number of shimming blocks on each position area; the arrangement with the smallest total number of shimming blocks arranged on the pole surface of the magnetic pole is determined among the multiple groups of arrangements, and the number of shimming blocks set on each position area is obtained;

[0135] Obtaining a second design number of shimming blocks set on each position area; calculating a difference in the number of shimming blocks on adjacent position areas, and smoothing the difference in the number to adjust the second design number of shimming blocks set on each position area; obtaining a third design number of shimming blocks set on each position area;

[0136] Determine whether the difference between the regional magnetic field change and the corresponding magnetic field difference is within a preset range, for example, whether the magnetic field error is within 5 Gauss: when the difference between the regional magnetic field change and the corresponding magnetic field difference is within the preset range, determine the third design quantity as the number of shim blocks to be set in each position area; when the difference between the regional magnetic field change and the corresponding magnetic field difference is outside the preset range, repeat the above step of determining the number of shim blocks to be set in each position area until the difference between the regional magnetic field change and the corresponding magnetic field difference is within the preset range.

[0137] The magnetic field optimization device for a cyclotron main magnet provided by the present invention is described below. The magnetic field optimization device for a cyclotron main magnet described below and the magnetic field optimization method for a cyclotron main magnet described above can be referred to each other.

[0138] Figure 5 : is a schematic diagram of the flow of the magnetic field optimization device of the cyclotron main magnet provided by the present invention, wherein a shim block is arranged on the magnetic pole surface of the main magnet, such as Figure 5 As shown, the device comprises:

[0139] A parameter determination module, used for determining the structural parameters of the magnetic pole surface, and determining the structural parameters of the shim block based on the structural parameters of the magnetic pole surface;

[0140] A region division module, used for dividing the magnetic pole surface into at least two position regions according to the structural parameters of the shim block;

[0141] A magnetic field determination module, used to determine the magnetic field variation amount generated by a single shim block in different position areas for each magnetic field area; determine the first current magnetic field of the main magnet and the theoretical magnetic field of the main magnet, and determine the magnetic field difference amount of each magnetic field area based on the first current magnetic field and the theoretical magnetic field; wherein the magnetic field area includes the position area and the central opening area of ​​the magnetic pole face;

[0142] The quantity determination module is used to determine the quantity of the shimming blocks to be set in each of the position areas based on the magnetic field difference and the magnetic field variation, so as to optimize the isochronism of the magnetic field of the cyclotron main magnet.

[0143] Based on any of the above embodiments, the regional magnetic field variation of the magnetic field region is obtained by linearly superposing the magnetic field variation generated by the shim blocks arranged on the pole faces of the magnetic poles in the magnetic field region;

[0144] Quantity determination module, specifically used for:

[0145] Based on the difference between the magnetic field difference amount in each magnetic field region and the magnetic field variation amount in the corresponding region, multiple groups of arrangements of the shim blocks on the magnetic pole surface are obtained; each group of arrangements is the first design quantity of the shim blocks on each position region;

[0146] The arrangement in which the total number of the shim blocks arranged on the pole faces of the magnetic poles is the smallest among the multiple groups of arrangements is determined, and the number of the shim blocks set in each of the position areas is obtained.

[0147] Based on any of the above embodiments, the magnetic field determination module is specifically used to:

[0148] Establishing a finite element model of the cyclotron main magnet, analyzing the finite element model to determine the simulated magnetic field variation generated by a single shim block in different position areas for each magnetic field area; determining the theoretical magnetic field variation generated by a single shim block in different position areas for each magnetic field area;

[0149] The mean square error between the theoretical magnetic field change and the simulated magnetic field change is calculated, and the mean square error is minimized to adjust the simulated magnetic field change generated by a single shim block in each magnetic field region, and obtain the magnetic field change generated by a single shim block in each magnetic field region at different position areas.

[0150] Based on any of the above embodiments, the magnetic field optimization device for the cyclotron main magnet further includes a smoothing processing module for:

[0151] Obtaining a second design quantity of the shim blocks to be set on each of the position areas;

[0152] The quantity difference of the shim blocks in adjacent position areas is calculated, and the quantity difference is smoothed to adjust the second design quantity of the shim blocks set in each position area.

[0153] Based on any of the above embodiments, the magnetic field optimization device for the cyclotron main magnet further includes a verification module, which is used to:

[0154] Obtaining a third design quantity of the shim blocks to be set on each of the position areas;

[0155] Determine the regional magnetic field variation of each of the magnetic field regions according to a third designed number of shim blocks arranged in each of the position regions;

[0156] When the difference between the regional magnetic field variation and the corresponding magnetic field difference is within a preset range, the third design quantity is determined as the quantity of the shim blocks to be set in each of the position areas.

[0157] Based on any of the above embodiments, the verification module is further used for:

[0158] When the difference between the regional magnetic field variation and the corresponding magnetic field difference is outside the preset range, repeat the above steps of determining the number of patch blocks to be set in each position area until the difference between the regional magnetic field variation and the corresponding magnetic field difference is within the preset range.

[0159] Based on any of the above embodiments, the structural parameters of the shim block include the shim block width, and the structural parameters of the magnetic pole surface include the magnetic pole surface width;

[0160] The area division module is specifically used for:

[0161] Determining the number of position areas on the pole face of the magnetic pole based on the ratio of the pole face width to the shim block width;

[0162] The number of position areas is divided radially from one side of the magnetic pole surface toward the other side according to the width of the shim block.

[0163] Based on any of the above embodiments, the magnetic field determination module is specifically used to:

[0164] determining the original magnetic field of each of the magnetic field regions;

[0165] After determining the target position area of ​​the magnetic pole surface of the main magnet and arranging a single shim block, a second current magnetic field of each magnetic field area;

[0166] Determine the magnetic field change amount generated by a single shim block in each magnetic field area in the target position area according to the difference between the second current magnetic field and the original magnetic field;

[0167] Repeat the step of determining the amount of magnetic field change generated by a single shim block in different target position areas for each magnetic field area to determine the amount of magnetic field change generated by a single shim block in different position areas for each magnetic field area.

[0168] Figure 6 An example of a structural diagram of an electronic device is shown in FIG. Figure 6 As shown, the electronic device may include: a processor (processor) 610 , a communication interface (Communications Interface) 620 , a memory (memory) 630 and a communication bus 640 , wherein the processor 610 , the communication interface 620 , and the memory 630 communicate with each other through the communication bus 640 . The processor 610 can call the logic instructions in the memory 630 to execute the magnetic field optimization method of the cyclotron main magnet, which method includes: determining the structural parameters of the magnetic pole surface, and determining the structural parameters of the shim block based on the structural parameters of the magnetic pole surface; dividing the magnetic pole surface into at least two position areas according to the structural parameters of the shim block; determining the magnetic field change amount generated by a single shim block in different position areas for each magnetic field area; determining the first current magnetic field of the main magnet and the theoretical magnetic field of the main magnet, and determining the magnetic field difference amount of each magnetic field area based on the first current magnetic field and the theoretical magnetic field; wherein the magnetic field area includes the position area and the central opening area of ​​the magnetic pole surface; determining the number of shim blocks to be set in each position area based on the magnetic field difference amount and the magnetic field change amount, so as to optimize the isochronism of the magnetic field of the cyclotron main magnet.

[0169] In addition, the logic instructions in the above-mentioned memory 630 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0170] On the other hand, the present invention also provides a computer program product, which includes a computer program, which can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the magnetic field optimization method of the cyclotron main magnet provided by the above methods, the method including: determining the structural parameters of the magnetic pole surface, and determining the structural parameters of the shim block based on the structural parameters of the magnetic pole surface; dividing the magnetic pole surface into at least two position areas according to the structural parameters of the shim block; determining the magnetic field change amount generated by a single shim block in different position areas for each magnetic field area; determining the first current magnetic field of the main magnet and the theoretical magnetic field of the main magnet, and determining the magnetic field difference amount of each magnetic field area based on the first current magnetic field and the theoretical magnetic field; wherein the magnetic field area includes the position area and the central opening area of ​​the magnetic pole surface; determining the number of shim blocks to be set on each position area based on the magnetic field difference amount and the magnetic field change amount, so as to optimize the isochronism of the magnetic field of the cyclotron main magnet.

[0171] On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to execute the magnetic field optimization method of the cyclotron main magnet provided by the above-mentioned methods, the method comprising: determining the structural parameters of the magnetic pole surface, and determining the structural parameters of the shim block based on the structural parameters of the magnetic pole surface; dividing the magnetic pole surface into at least two position areas according to the structural parameters of the shim block; determining the magnetic field change amount generated by a single shim block in different position areas for each of the magnetic field areas; determining the first current magnetic field of the main magnet and the theoretical magnetic field of the main magnet, and determining the magnetic field difference amount of each of the magnetic field areas based on the first current magnetic field and the theoretical magnetic field; wherein the magnetic field area includes the position area and the central opening area of ​​the magnetic pole surface; determining the number of the shim blocks to be set in each of the position areas based on the magnetic field difference amount and the magnetic field change amount, so as to optimize the isochronism of the magnetic field of the cyclotron main magnet.

[0172] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0173] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0174] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for optimizing the magnetic field of a cyclotron main magnet, characterized in that: The shim block is arranged on the magnetic pole surface of the main magnet, including: Determine the structural parameters of the magnetic pole surface, and determine the structural parameters of the shim block based on the structural parameters of the magnetic pole surface; Dividing the magnetic pole surface into at least two position areas according to the structural parameters of the shim block; Determine the magnetic field variation amount generated by a single shim block in each magnetic field area at different position areas; determine the first current magnetic field of the main magnet and the theoretical magnetic field of the main magnet, and determine the magnetic field difference amount of each magnetic field area based on the first current magnetic field and the theoretical magnetic field; wherein the magnetic field area includes the position area and the central opening area of ​​the magnetic pole face; The number of the shim blocks to be arranged in each of the position areas is determined based on the magnetic field difference and the magnetic field variation, so as to optimize the isochronism of the magnetic field of the cyclotron main magnet.

2. The method for optimizing the magnetic field of a cyclotron main magnet according to claim 1, characterized in that: The regional magnetic field variation of the magnetic field region is obtained by linearly superposing the magnetic field variation generated by the shim blocks arranged on the pole faces of the magnetic poles in the magnetic field region; Determining the number of shimming blocks to be set in each of the position areas based on the magnetic field difference and the magnetic field variation specifically includes: Based on the difference between the magnetic field difference amount in each magnetic field region and the magnetic field variation amount in the corresponding region, multiple groups of arrangements of the shim blocks on the magnetic pole surface are obtained; each group of arrangements is the first design quantity of the shim blocks on each position region; The arrangement in which the total number of the shim blocks arranged on the pole faces of the magnetic poles is the smallest among the multiple groups of arrangements is determined, and the number of the shim blocks set in each of the position areas is obtained.

3. The method for optimizing the magnetic field of a cyclotron main magnet according to claim 1, characterized in that: Determining the amount of change in magnetic field generated by a single shim block in different position areas for each magnetic field area specifically includes: Establishing a finite element model of the cyclotron main magnet, analyzing the finite element model to determine the simulated magnetic field variation generated by a single shim block in different position areas for each magnetic field area; determining the theoretical magnetic field variation generated by a single shim block in different position areas for each magnetic field area; The mean square error between the theoretical magnetic field change and the simulated magnetic field change is calculated, and the mean square error is minimized to adjust the simulated magnetic field change generated by a single shim block in each magnetic field region, and obtain the magnetic field change generated by a single shim block in each magnetic field region at different position areas.

4. The method for optimizing the magnetic field of a cyclotron main magnet according to claim 2, characterized in that: Before obtaining the number of the shimming blocks set in each of the location areas, the method further includes: Obtaining a second design quantity of the shim blocks to be set on each of the position areas; The quantity difference of the shim blocks in adjacent position areas is calculated, and the quantity difference is smoothed to adjust the second design quantity of the shim blocks set in each position area.

5. The method for optimizing the magnetic field of a cyclotron main magnet according to claim 4, characterized in that: After smoothing the quantity difference, the method further includes: Obtaining a third design quantity of the shim blocks to be set on each of the position areas; Determine the regional magnetic field variation of each of the magnetic field regions according to a third designed number of shim blocks arranged in each of the position regions; When the difference between the regional magnetic field variation and the corresponding magnetic field difference is within a preset range, the third design quantity is determined as the quantity of the shim blocks to be set in each of the position areas.

6. The method for optimizing the magnetic field of a cyclotron main magnet according to claim 5, characterized in that: After determining the regional magnetic field variation of each magnetic field region according to the third designed number of shim blocks arranged in each position region, the method further comprises: When the difference between the regional magnetic field variation and the corresponding magnetic field difference is outside the preset range, repeat the above steps of determining the number of patch blocks to be set in each position area until the difference between the regional magnetic field variation and the corresponding magnetic field difference is within the preset range.

7. The method for optimizing the magnetic field of a cyclotron main magnet according to claim 1, characterized in that: The structural parameters of the shim block include the shim block width, and the structural parameters of the magnetic pole face include the magnetic pole face width; The magnetic pole surface is divided into at least two position areas according to the structural parameters of the shim block, specifically including: Determining the number of position areas on the pole face of the magnetic pole based on the ratio of the pole face width to the shim block width; The number of position areas is divided radially from one side of the magnetic pole surface toward the other side according to the width of the shim block.

8. The method for optimizing the magnetic field of a cyclotron main magnet according to claim 1, characterized in that: Determining the amount of change in magnetic field generated by a single shim block in different position areas for each magnetic field area specifically includes: determining the original magnetic field of each of the magnetic field regions; After determining the target position area of ​​the magnetic pole surface of the main magnet and arranging a single shim block, a second current magnetic field of each magnetic field area; Determine the magnetic field change amount generated by a single shim block in each magnetic field area in the target position area according to the difference between the second current magnetic field and the original magnetic field; Repeat the step of determining the amount of magnetic field change generated by a single shim block in different target position areas for each magnetic field area to determine the amount of magnetic field change generated by a single shim block in different position areas for each magnetic field area.

9. A magnetic field optimization device for a cyclotron main magnet, characterized in that: The shim block is arranged on the magnetic pole surface of the main magnet, including: A parameter determination module, used for determining the structural parameters of the magnetic pole surface, and determining the structural parameters of the shim block based on the structural parameters of the magnetic pole surface; A region division module, used for dividing the magnetic pole surface into at least two position regions according to the structural parameters of the shim block; A magnetic field determination module, used to determine the magnetic field variation amount generated by a single shim block in different position areas for each magnetic field area; determine the first current magnetic field of the main magnet and the theoretical magnetic field of the main magnet, and determine the magnetic field difference amount of each magnetic field area based on the first current magnetic field and the theoretical magnetic field; wherein the magnetic field area includes the position area and the central opening area of ​​the magnetic pole face; The quantity determination module is used to determine the quantity of the shimming blocks to be set in each of the position areas based on the magnetic field difference and the magnetic field variation, so as to optimize the isochronism of the magnetic field of the cyclotron main magnet.

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the magnetic field optimization method for the cyclotron main magnet according to any one of claims 1 to 8 is implemented.

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