Method and device for precise regulation of an excitation power supply system of a complex superconducting magnet

Abstract

The application discloses a kind of complex superconducting magnet excitation power system accurate regulation method and device, the device includes upper and lower two layers annular main coils that are symmetrically arranged along the accelerator center plane, multiple circumferential uniform arrangement limit coils in each layer annular main coil, multiple pad-up coils that are arranged from small radius to large radius in each limit coil, and main circuit loop that flows through main coil, main current loop and multiple branch current loops that flow through limit coil and pad-up coil;Main current loop provides basic operating current for main coil, each limit coil and pad-up coil, and branch current loop is provided with an independent trimming power supply on each branch, and the independent trimming power supply fine tunes the current of limit coil and pad-up coil in each branch;The method comprises: using main loop power supply to power all series superconducting coils;Independently adjust the trimming power supply of superconducting coil on each branch;The application can realize independent adjustment of coil current by increasing a small amount of thermal load.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high-temperature superconducting cyclotrons, and particularly relates to a precise adjustment method and device for an excitation power supply system of a complex superconducting magnet. BACKGROUND

[0002] Isochronism is one of the important indicators for measuring the performance of a cyclotron. In a cyclotron with good isochronism, the frequency of the particles rotating in the cyclotron is consistent with the high-frequency frequency, which ensures that the particles are accelerated at the voltage peak value each time they pass through the high-frequency cavity accelerator gap, and the particles can reach the extraction position through fewer turns, thereby reducing the beam loss in the cyclotron. Generally, the magnetic field of a cyclotron cannot meet the isochronism requirement at the initial stage of magnet construction, and the magnetic field needs to be corrected by magnet processing padding.

[0003] Commonly used magnetic field padding methods for normal-temperature magnet cyclotrons include: (1) strip processing, that is, a detachable strip is installed on the side of the magnetic pole, and the magnetic field is padded by processing the width of the strip; and (2) magnetic pole side block pasting, that is, a rectangular block with different widths is pasted on the side of the magnet to correct the magnetic field.

[0004] Most superconducting cyclotrons in the world use the method of adjusting the coil and the rod to pad the magnetic field, and some use the method of processing the magnet of a conventional accelerator.

[0005] In a compact high-temperature superconducting cyclotron, the size of the accelerator has been reduced to the limit, and it is difficult to install a magnetic field adjusting rod. If the conventional magnet processing method is used for padding, the weight and size of the accelerator will be greatly increased, which is contrary to the original intention of the compact superconducting accelerator.

[0006] The problem with using an adjusting coil is that if a normal electromagnet coil scheme is used, the adjustment range is limited due to the heating of the coil in a vacuum, and if a superconducting coil scheme is used, due to the structural problems of the existing high-temperature superconducting coil, the utilization rate of the superconducting coil is not high, the cost of superconducting material is increased, or the current of the superconducting coil is too large, which increases the cost of the low-temperature system and makes manufacturing difficult. SUMMARY

[0007] In view of the deficiencies in the prior art, a precise adjustment method and device for an excitation power supply system of a complex superconducting magnet are proposed, which aims to solve the problems that if a normal electromagnet coil scheme is used, the adjustment range is limited due to the heating of the coil in a vacuum, and if a superconducting coil scheme is used, due to the structural problems of the existing high-temperature superconducting coil, the utilization rate of the superconducting coil is not high, the cost of superconducting material is increased, or the current of the superconducting coil is too large, which increases the cost of the low-temperature system.

[0008] The application proposes the following technical solutions to solve the problems in the prior art:

[0009] The application discloses a precise regulating device of an excitation power supply system of a complex superconducting magnet, and has the characteristics that the regulating device comprises two layers of annular main coils symmetrically arranged along the center plane of an accelerator, a plurality of magnetic pole coils symmetrically arranged in each layer of the annular main coils, a plurality of compensation coils arranged from a small radius to a large radius in each layer of the main coils, a main current loop flowing through the main coils, a main current loop and a micro-adjusting current loop flowing through the magnetic pole coils and the compensation coils, and a main current loop for providing basic operating currents for the main coils, the magnetic pole coils and the compensation coils; an independent micro-adjusting power supply is arranged on the micro-adjusting current loop, and the independent micro-adjusting power supply is used for micro-adjusting the currents of the magnetic pole coils and the compensation coils in the respective branches; the currents of each magnetic pole coil and each compensation coil are equal to the sum of the current of the main current loop and the current of the micro-adjusting current loop; all the main coils, the magnetic pole coils and the compensation coils of the device are arranged in a low-temperature thermostat, and the main power supply and the micro-adjusting power supply are arranged outside the low-temperature thermostat; the micro-adjusting current loop is a branch formed by two layers of compensation coils with the same radius symmetrically arranged on both sides of the center plane of the accelerator, and an independent micro-adjusting power supply is arranged on each branch, and the independent micro-adjusting power supply is used for micro-adjusting the currents of the compensation coils in the branch; the two layers of compensation coils with the same radius refer to the compensation coils in the two layers having the same radius from the center point of the accelerator, and

[0010] The micro-adjusting current loop is a branch formed by all the magnetic pole coils symmetrically arranged on both sides of the center plane of the accelerator, and an independent micro-adjusting power supply is arranged on each branch, and the independent micro-adjusting power supply is used for micro-adjusting the currents of the magnetic pole coils in the branch.

[0011] Further, the main coils, the magnetic pole coils, the compensation coils, the low-temperature end current leads of the main current loop and the low-temperature end current leads of the micro-adjusting current loop are arranged in a 70K cold screen; the high-temperature end copper leads R5 of the main current loop and the high-temperature end copper leads R2 of the micro-adjusting current loop are arranged between the 70K screen and a 300K shell, the resistance of the external power supply cable of the main loop is R6, and the resistance of the external power supply cable of the micro-adjusting current loop is R1.

[0012] Further, the current amperage of the main current loop is dozens of times of the current amperage of the micro-adjusting current loop.

[0013] Further, when the current of the main current loop needs to reach a level of 300A, the current of the micro-adjusting current loop only needs to be less than 10A to meet the magnetic field regulating requirement.

[0014] Further, when the independent micro-adjusting power supply micro-adjusts the currents of the magnetic pole coils and the compensation coils in the branch, the micro-adjusting power supply can reversibly adjust the currents from large to small or from small to large.

[0015] Furthermore, when this independent fine-tuning power supply fine-tunes the current of the magnetic pole coil and the padding coil in the branch, it is an online adjustment.

[0016] A method for precisely adjusting the excitation power supply system of a complex superconducting magnet, characterized by:

[0017] Step 1: After the system has cooled down, power is supplied to all the superconducting coils connected in series using the main current loop power supply; these superconducting coils connected in series include all the main coils, limiting coils and padding coils connected in series.

[0018] Step 2: After the power supply current stabilizes, independently adjust the fine-tuning power supply of the superconducting coil on each branch so that the current of the superconducting coil on each branch reaches the design value; wherein, the coils of all fine-tuning circuits are independently powered to achieve the purpose of independently adjusting the coil current.

[0019] Step 3: Perform magnetic field measurements. Based on the magnetic field measurement results, adjust the fine-tuning power supply current of each superconducting coil on each branch to ensure that the magnetic field meets the isochronism requirements of the accelerator.

[0020] Step 4: Does the current magnetic field meet the isochronism requirements of the accelerator? If it does not meet the isochronism requirements, return to Step 2. If it meets the isochronism requirements, then end the magnetic field adjustment of the high-temperature superconducting cyclotron accelerator.

[0021] Advantages and effects of the invention

[0022] This invention utilizes existing coil structures to achieve isochronous regulation of the magnetic field by independently adjusting the current in the superconducting coil via a fine-tuning power supply. It offers the following advantages:

[0023] 1) This invention achieves isochronous adjustment of the magnetic field without increasing the number of coils or the amount of magnetic material, without occupying valuable central space, and has a simple mechanical structure.

[0024] 2) The coil current of this invention adopts a scheme of main current + fine-tuning current, so that the coil current can be independently adjusted by only increasing a small amount of heat load.

[0025] 3) Traditional magnetic field adjustment using ferromagnetic materials is irreversible, while this invention adjusts the magnetic field by changing the current, making it reversible.

[0026] 5. Traditional adjustments require disassembly and assembly and cannot be performed online. This invention enables online adjustment, thereby improving the debugging efficiency of the accelerator.

[0027] 6. Compared to independently powering all coils, this invention reduces the power consumption of most power supplies (previously, all power supplies needed to be 300A*10V; now, only one 300A*10V power supply is needed, and the rest can be 10A*5V). This invention also reduces the stability requirements for most power supplies (previously, all power supplies needed to achieve a stability of 10ppm; now, only one power supply needs 10ppm, and the others only need 100ppm stability). This significantly reduces power supply procurement costs. Attached Figure Description

[0028] Figure 1 This is a circuit diagram of a magnetic field conditioning device for a high-temperature superconducting cyclotron accelerator according to the present invention;

[0029] Figure 2 The first viewpoint showing the positions of the main coil, magnetic limit coil, and padding coil on both sides of the central plane of the present invention;

[0030] Figure 3 The second perspective shows the positions of the main coil, magnetic limit ring, and padding coil on both sides of the central plane of the present invention.

[0031] Figure 4 The circuit diagram for this invention is optimized considering the resistance on the wires. Detailed Implementation

[0032] Design principle of the invention

[0033] 1. Innovation of this invention: The innovation lies in the fact that the magnetic field adjustment adopts a scheme of main current + fine-tuning current, which allows for independent adjustment of the coil current with only a small increase in heat load.

[0034] The first problem solved was the main current + fine-tuning current scheme. This resolved the issue of excessive superconducting coil current leading to excessive lead current, which increased the cost of the cryogenic system when using superconducting coils to adjust the magnetic field. In this embodiment, the main current ampere is 30 times the fine-tuning current ampere, and the fine-tuning current ampere is 1 / 30th of the main current ampere. Since the fine-tuning current is only 1 / 30th of the main current, for each coil, only a 1 / 30th increase in the original heat load is needed to achieve independent adjustment of the coil current. Therefore, the problem of excessively increased heat load on the cryogenic system due to independent adjustment of the superconducting coil current is solved.

[0035] The second problem addressed is that traditional magnetic field adjustment using ferromagnetic materials is irreversible. This irreversibility means that during the patching and repair process, only the patch itself can be cut, not added (because the material of each batch of patches is not entirely the same, and bonding two different materials together will affect the uniformity of the magnetic field). Therefore, only a small amount must be cut each time; cutting too much renders the entire patch unusable. This irreversible magnetic field patching method is time-consuming and labor-intensive. This invention employs online and reversible adjustment, effectively improving work efficiency.

[0036] 2. Design Challenges of this Invention: The challenge lies in balancing the density of the magnetic field padding with the problem of excessive thermal load on the cryogenic system caused by too many current leads in the padding coils. Ensuring the density of the magnetic field padding requires a sufficient number of padding coils along the small to large radii of each magnetic limit coil. Sparse spacing between padding coils results in uneven padding density, leading to inadequate magnetic field padding in areas without padding coils. However, increasing the density of the padding coils also increases the number of current leads. If each padding coil carries the main circuit current, the thermal load on the cryogenic system increases exponentially relative to the main circuit, resulting in excessively high costs for maintaining the cryogenic environment. This cryogenic environment refers to a cold screen environment below 70K. Since the main coil, magnetic pole coils, padding coils, main circuit current leads, and fine-tuning circuit all have their cryogenic current leads located inside the 70K cold screen, maintaining a temperature below 70K requires significantly increased cooling costs for the 70K cold screen when the current in the padding coils within the 70K cold screen overheats.

[0037] 3. Solution of this invention: All main coils, pole coils, and padding coils are connected in series. The effect of this series connection is that the main circuit current flows through the pole coils and padding coils in each branch circuit, meaning the main coils, pole coils, and padding coils share a single main circuit current. Assuming there are 8 (one group) magnetic limit coils and 56 (7 groups) padding coils in the upper and lower main coil layers, conventional methods would require 9 main circuit current leads. Using this invention, only one main circuit current lead and 8 leads representing a fraction of the main circuit current are needed. Simultaneously, independent fine-tuning circuits are added to all pole coils and padding coils. The current in these fine-tuning circuits is only a fraction of the main circuit current, sufficient to meet the difference in magnetic field padding. Furthermore, the current in the superconducting coil of the fine-tuning circuit uses a scheme of main current + fine-tuning current. Although the current in the fine-tuning circuit itself is only a fraction of the main circuit current, the superconducting coil simultaneously receives the superposition of the main circuit current and the fine-tuning circuit current, thus ensuring normal operation.

[0038] Based on the above principles, this invention designs a precise adjustment device for the excitation power supply system of complex superconducting magnets, such as... Figures 1-3As shown, its features are as follows: the adjustment device includes two layers of annular main coils symmetrically arranged along the central plane of the accelerator, multiple circumferentially uniformly arranged magnetic pole coils within each layer of the annular main coil, multiple padding coils arranged from small radius to large radius within each layer of the main coil, as well as a main current loop flowing through the main coils, a main current loop flowing through the magnetic pole coils and the padding coils, and their respective fine-tuning current loops; the main current loop provides the basic operating current for the main coils, each magnetic pole coil, and the padding coils, and the fine-tuning current loop is equipped with an independent fine-tuning power supply, which finely adjusts the current of the magnetic pole coils and padding coils in their respective branches; the current of each magnetic pole coil and padding coil = the current of the main current loop + the current of the fine-tuning loop; all the main coils, magnetic pole coils, and padding coils of this device are inside the cryogenic thermostat, while the main power supply and the fine-tuning power supply are outside the cryogenic thermostat.

[0039] like Figure 1 As shown, the fine-tuning current loop is formed by two layers of padding coils with the same radius symmetrically arranged on both sides of the accelerator's central plane as one branch. Each branch is equipped with an independent fine-tuning power supply, which fine-tunes the current of the padding coil on that branch. The two layers of padding coils with the same radius refer to the two layers of padding coils having the same radius from the center point of the accelerator.

[0040] like Figure 1 As shown, the fine-tuning current loop is formed by symmetrically arranging all the magnetic pole coils on both sides of the accelerator's central plane as one branch, and each branch is equipped with an independent fine-tuning power supply, which finely adjusts the current of the magnetic pole coil on that branch.

[0041] Supplementary note 1

[0042] A. As Figure 1 As shown, the central plane of the accelerator is Figure 1 The central plane of the magnet;

[0043] B. Figure 1 There are two types of branches: the one on the left is the magnetic pole coil branch; the one in the middle and on the right is the padding coil branch.

[0044] C. The magnetic pole coil branch consists of eight magnetic pole coils, including the four upper-layer magnetic pole coils and the four lower-layer magnetic pole coils, forming a single branch.

[0045] D. A branch of the padding coil consists of two layers of padding coils with the same radius on the upper and lower layers. There are seven groups of padding coils with the same radius, ranging from small to large radius, forming seven branches of the padding coil. These seven branches include four branches within each magnetic pole coil and three branches between magnetic pole coils. Figure 2 As shown.

[0046] like Figure 1 , Figure 4 As shown, the main coil, magnetic pole coil, padding coil, low-temperature current lead of the main current circuit, and low-temperature current lead of the fine-tuning current circuit are arranged inside the 70K cold screen; the high-temperature copper lead R5 of the main current circuit and the high-temperature copper lead R2 of the fine-tuning current circuit are between the 70K screen and the 300K outer shell; the resistance of the external power supply cable of the main circuit is R6, and the resistance of the external power supply cable of the fine-tuning current circuit is R1.

[0047] The current amperes in the main current loop are tens of times that in the fine-tuning current loop.

[0048] When the current in the main current loop needs to reach 300A, the current in the fine-tuning current loop only needs to be less than 10A to meet the magnetic field regulation requirements.

[0049] When this independent fine-tuning power supply fine-tunes the current of the magnetic pole coil and padding coil in the branch, it is a reversible adjustment. The fine-tuning power supply can adjust the current from large to small, and also adjust the current from small to large.

[0050] This independent fine-tuning power supply allows for online adjustment of the current in the magnetic pole coil and padding coil within the branch circuit.

[0051] A method for magnetic field conditioning in a high-temperature superconducting cyclotron accelerator, characterized by:

[0052] Step 1: After the system has cooled down, power is supplied to all the superconducting coils connected in series using the main current loop power supply; these superconducting coils connected in series include all the main coils, limiting coils and padding coils connected in series.

[0053] Step 2: After the power supply current stabilizes, independently adjust the fine-tuning power supply of the superconducting coil on each branch so that the current of the superconducting coil on each branch reaches the design value; wherein, the coils of all fine-tuning circuits are independently powered to achieve the purpose of independently adjusting the coil current.

[0054] Step 3: Perform magnetic field measurements. Based on the magnetic field measurement results, adjust the fine-tuning power supply current of each superconducting coil on each branch to ensure that the magnetic field meets the isochronism requirements of the accelerator.

[0055] Supplementary note 2

[0056] like Figure 2 As shown, this embodiment of the invention has a total of eight branches: seven padding coil branches and one magnetic pole coil branch. The seven padding coil branches consist of four within each magnetic pole coil and three between magnetic pole coils.

[0057] Step 4: Does the current magnetic field meet the isochronism requirements of the accelerator? If it does not meet the isochronism requirements, return to Step 2. If it meets the isochronism requirements, then end the magnetic field adjustment of the high-temperature superconducting cyclotron accelerator.

[0058] It should be emphasized that the above specific embodiments are merely explanations of the present invention and are not intended to limit the present invention. After reading this specification, those skilled in the art can make modifications to the above embodiments without contributing any inventive step, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A precise adjustment device for the excitation power supply system of a complex superconducting magnet, characterized in that: The adjustment device includes two layers of annular main coils symmetrically arranged along the central plane of the accelerator, multiple circumferentially uniformly arranged magnetic pole coils within each layer of the main coils, multiple padding coils arranged from small to large radius within each layer of the main coils, a main current loop flowing through the main coils, a main current loop flowing through the magnetic pole coils and the padding coils, and their respective fine-tuning current loops. The main current loop provides the basic operating current for the main coils, each magnetic pole coil, and the padding coils. The fine-tuning current loop has an independent fine-tuning power supply, which fine-tunes the current of the magnetic pole coils and padding coils in their respective branches. The current of each magnetic pole coil and padding coil = main current loop current + fine-tuning loop current. All the main coils of this device... All magnetic pole coils and padding coils are located inside the cryogenic thermostat, while the main power supply and fine-tuning power supply are located outside the cryogenic thermostat. The fine-tuning current loop is formed by two layers of padding coils with the same radius symmetrically arranged on both sides of the accelerator's central plane, each forming a branch. Each branch has an independent fine-tuning power supply, which fine-tunes the current of the padding coil on that branch. The two layers of padding coils with the same radius refer to the two layers of padding coils having the same radius from the center point of the accelerator. The fine-tuning current loop is formed by all the magnetic pole coils symmetrically arranged on both sides of the accelerator's central plane, each forming a branch. Each branch has an independent fine-tuning power supply, which fine-tunes the current of the magnetic pole coil on that branch.

2. The precise adjustment device for the excitation power supply system of a complex superconducting magnet according to claim 1, characterized in that: The main coil, magnetic pole coil, padding coil, low-temperature current lead of the main current circuit, and low-temperature current lead of the fine-tuning current circuit are arranged inside the 70K cold shield; the high-temperature copper lead R5 of the main current circuit and the high-temperature copper lead R2 of the fine-tuning current circuit are between the 70K screen and the 300K shell; the resistance of the external power supply cable of the main circuit is R6, and the resistance of the external power supply cable of the fine-tuning current circuit is R1.

3. The precise adjustment device for the excitation power supply system of a complex superconducting magnet according to claim 1, characterized in that: The current amperes in the main current loop are tens of times that in the fine-tuning current loop.

4. The precise adjustment device for the excitation power supply system of a complex superconducting magnet according to claim 3, characterized in that: When the current in the main current loop needs to reach 300A, the current in the fine-tuning current loop only needs to be less than 10A to meet the magnetic field regulation requirements.

5. The precise adjustment device for the excitation power supply system of a complex superconducting magnet according to claim 1, characterized in that: When this independent fine-tuning power supply fine-tunes the current of the magnetic pole coil and padding coil in the branch, it is a reversible adjustment. The fine-tuning power supply can adjust the current from large to small, and also adjust the current from small to large.

6. The precise adjustment device for the excitation power supply system of a complex superconducting magnet according to claim 1, characterized in that: This independent fine-tuning power supply allows for online adjustment of the current in the magnetic pole coil and padding coil within the branch circuit.

7. A method for precisely adjusting the excitation power supply system of a complex superconducting magnet, based on a device for precisely adjusting the excitation power supply system of a complex superconducting magnet according to any one of claims 1-6, characterized in that: Step 1: After the system has cooled down, power is supplied to all the superconducting coils connected in series using the main current loop power supply; these superconducting coils connected in series include all the main coils, limiting coils and padding coils connected in series. Step 2: After the power supply current stabilizes, independently adjust the fine-tuning power supply of the superconducting coil on each branch so that the current of the superconducting coil on each branch reaches the design value; wherein, the coils of all fine-tuning circuits are independently powered to achieve the purpose of independently adjusting the coil current. Step 3: Perform magnetic field measurements. Based on the magnetic field measurement results, adjust the fine-tuning power supply current of each superconducting coil on each branch to ensure that the magnetic field meets the isochronism requirements of the accelerator. Step 4: Does the current magnetic field meet the isochronism requirements of the accelerator? If it does not meet the isochronism requirements, return to Step 2. If it meets the isochronism requirements, then end the magnetic field adjustment of the high-temperature superconducting cyclotron accelerator.

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