High-field multi-layer pure coil cos theta distribution bidirectional scanning magnet and use method

Abstract

The invention relates to a high-field multi-layer pure coil cos distribution bidirectional scanning magnet and a use method. The scanning magnet comprises a positioning tool; each coil layer sleeve is formed by enclosing a pair of coil layers, each coil layer is formed by winding a wire into a semi-cylindrical surface in a shape like a Chinese character'hui 'through a positioning tool, the two ends of the wire extend out of the same end part of the semi-cylindrical surface, and a pair of semi-cylindrical surfaces are enclosed and butted to form a cylindrical surface structure. According to the invention, the uniformity of the target area and range can be improved.

Description

Technical Field

[0001] This invention relates to the field of scanning magnet technology for particle accelerator terminals, specifically to a high-field multilayer pure coil cosine... Distribution of bidirectional scanning magnets and their usage. Background Technology

[0002] Scanning magnets are a special type of magnet required at the end of a particle accelerator. Their main function is to scan the beam into a square or circular field (uniform scanning) or into a discrete lattice of points in a plane (point scanning) by horizontal and vertical scanning.

[0003] Core-dominated scanning magnets present numerous problems. Considering the magnet's operating mode, core-dominated scanning magnets face the following issues: 1. Eddy current heating effect: Continuous and rapid changes in magnetic flux induce eddy currents in the core, causing continuous heating. Prolonged heat exposure can affect coil lifespan and may even burn out the coil or supporting components. 2. Eddy current magnetic effect: The magnetic field generated by eddy currents partially cancels out the main magnetic field, causing the transient magnetic field to lag behind the static main magnetic field. Furthermore, the magnetic field generated by eddy currents and the main magnetic field superimpose, negatively impacting the uniformity of the main magnetic field and causing distortion. 3. End effect: Determined by the silicon steel sheet stacking method, the eddy current thermomagnetic effect is particularly pronounced at the magnet ends. ① Magnetic field delay and distortion are more severe at the ends; ② Eddy current heating at the ends is more significant than in the core body, making it a localized heat source. 4. Noise: The noise of the scanning magnet mainly comes from coil vibration and core squealing. The core squealing noise is very significant and difficult to eliminate. Medical particle accelerator terminals are very close to patients, and the loud noise can cause discomfort.

[0004] Unidirectional scanning magnets typically need to be installed in pairs, one for horizontal scanning and one for vertical scanning. After the horizontal scanning is completed, the beam envelope widens along the horizontal direction, significantly increasing the air gap of the vertical scanning magnet. Since the magnet's power is proportional to the square of the air gap, this results in a surge in the vertical scanning magnet's power. Furthermore, installing two scanning magnets in pairs increases the installation distance and consequently, the scanning distance.

[0005] Therefore, under normal circumstances, traditional scanning magnets, due to the thermomagnetic effect of the iron core, electromagnetic noise of the iron core, and the increase in air gap caused by unidirectional scanning, will cause many problems when the main magnetic field is increased. Low-field operation will significantly increase the scanning distance or drastically limit the scanning range. For rotating gantry systems used in irradiation therapy, the increase in scanning distance will lead to a significant increase in the gantry's rotation radius and weight, significantly increasing the difficulty and additional costs of rotational positioning. Furthermore, some scholars have proposed using superconducting cable scanning magnets. This method can increase the magnetic field by increasing the scanning current; however, since scanning magnets operate in a continuously changing mode, the superconducting magnet solution is currently largely at the conceptual stage and difficult to implement in engineering. Summary of the Invention

[0006] To address the above problems, the purpose of this invention is to provide a high-field multilayer pure coil cosine... A bidirectional scanning magnet and its usage method are described. This magnet has no iron core and is only excited by water-cooled coils. To achieve a high field, a multi-layered nested coil structure is used, with horizontal and vertical coils nested sequentially to achieve bidirectional scanning. To improve the uniformity of the target area and range, the conductors in the excitation winding are arranged at a cosine angle. distributed.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: The high-field multilayer pure coil cos Distributed bidirectional scanning magnets, including: Positioning fixtures; The coil layer sleeve is formed by a pair of coil layers. Each coil layer is formed by a positioning fixture that winds a wire in a U-shape to form a semi-cylindrical surface. The two ends of the wire extend out of the same end of the semi-cylindrical surface. The pair of semi-cylindrical surfaces are joined together to form a cylindrical structure.

[0008] The high-field multilayer pure coil cos The distributed bidirectional scanning magnets are preferably arranged in a single coil layer, which is formed by a pair of coil layers arranged in the X direction.

[0009] The high-field multilayer pure coil cos The distributed bidirectional scanning magnets are preferably provided. The coil sleeve consists of two layers. The first layer of the coil sleeve is formed by a pair of coil layers arranged in the X direction. The second layer of the coil sleeve is formed by a pair of coil layers arranged in the Y direction. The second layer of the coil sleeve is fitted over the first layer of the coil sleeve.

[0010] The high-field multilayer pure coil cos The distributed bidirectional scanning magnets are preferably provided. The coil layers are multiple layers, and the coil layers are alternately nested in the winding direction according to the XYYXYXXY pattern. The mating surfaces of a pair of semi-cylindrical surfaces on adjacent coil layers are perpendicular to each other.

[0011] The high-field multilayer pure coil cos The coil layer has a double-layer structure, preferably with bidirectional scanning magnets distributed in the coil layer.

[0012] The high-field multilayer pure coil cos The bidirectional scanning magnet is distributed, and preferably, both ends of the wire are connected to copper busbar connectors.

[0013] The high-field multilayer pure coil cos The bidirectional scanning magnet is distributed. Preferably, the positioning fixture includes a winding mold and a positioning pad. The winding mold is used to wind the coil layer, and the positioning pad is used to isolate adjacent wires on the coil layer to determine the position of the wires.

[0014] The high-field multilayer pure coil cos The winding mold preferably includes a base, a winding base column, a limiting plate, a limiting clamp, and a fixing component, and is equipped with a bidirectional scanning magnet. The winding base post is disposed on the upper surface of the base to form a raised structure; The limiting plate is disposed on the top of the winding base column and is fixed to the base by a number of fasteners; The two limiting clamps are respectively sleeved on the outside of the winding base column and fixed to the base, and are used to limit the winding coil in the height direction.

[0015] This invention also provides a high-field multilayer pure coil cos The method for using a distributed bidirectional scanning magnet includes the following steps: Using a single-layer unidirectional magnet with a single coil layer, it is possible to achieve scanning of the magnetic field in the Y direction and the X direction, or scanning of the magnetic field in the X direction and the Y direction. Using a multi-layer bidirectional magnet with two or more coil layers, high-field bidirectional scanning can be achieved.

[0016] The method of use, preferably, involves achieving a magnetic field in the Y direction, scanning in the X direction, and a conductor angle distribution that conforms to... If a magnetic field is achieved in the X direction and scanning is performed in the Y direction, the wire distribution should conform to... Where N is the total number of conductors in the corresponding 1 / 4 quadrant; i is the conductor number; .

[0017] The present invention has the following advantages due to the adoption of the above technical solutions: (1) The bidirectional scanning scheme itself can reduce the air gap of the magnet, thereby reducing the cost of power supply and magnet.

[0018] (2) By adopting a multi-layer structure, a higher magnetic field can be achieved. In the example, the magnetic field is 6 kGauss. Compared with the traditional 2 kGauss scanning magnet, the scanning distance is shortened by 2 / 3. If bidirectional integration is considered, the installation distance is reduced by at least 1 / 2.

[0019] (3) Since the present invention uses pure coils, it completely solves the problems of noise, heat generation and delay and distortion of dynamic magnetic field caused by iron core; at the same time, the pure coil design can greatly reduce the magnet inductance. In the example of the present invention, although the number of turns is large, the inductance is similar to that of traditional scanning magnets, so the inductance voltage is not significantly increased, and the power supply design difficulty and cost are not increased.

[0020] (4) Achieving lightweight design: Two traditional scanning magnets with a magnetic field of 2kGauss and an effective length of 500mm weigh about 760kg. This invention increases the magnetic field to 6kGauss, while the weight is only 140kg, thus achieving lightweight design of the magnet.

[0021] (5) Under the combined effect of the above factors, by increasing the magnetic field and realizing bidirectional scanning, the scanning distance is greatly reduced, and the weight and volume of the medical rotating gantry can be reduced to about 1 / 4. Its positioning difficulty is significantly reduced and its positional accuracy is significantly improved. By adopting a pure coil design, there is no need to consider the dynamic magnetic field delay and distortion caused by the iron core, and the positional accuracy of particle scanning will be further improved. Attached Figure Description

[0022] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. In the drawings: Figure 1 This is a two-dimensional distribution diagram of a single-layer unidirectional conductor according to the present invention; Figure 2 This is a two-dimensional distribution diagram of the single-layer bidirectional conductor of the present invention; Figure 3 This is a comparison diagram of the XYYXYXXY nesting method of the present invention and the traditional XYXYXYXY nesting method, wherein (a) is a schematic diagram of the traditional XYXYXYXY nesting method and (b) is a schematic diagram of the XYYXYXXY nesting method; Figure 4 This is a schematic diagram of the coil layer structure of the present invention; Figure 5 This is a cross-section and a simplified three-dimensional model diagram of the present invention; Figure 6 This is a schematic diagram of the winding mold of the positioning tooling of the present invention; Figure 7 This is a schematic diagram of the position pad of the positioning tooling of the present invention; Figure 8 This is a schematic diagram of the single-layer coil winding of the present invention.

[0023] The markings in the attached diagram are as follows: 1-Coil layer sleeve; 101-Coil layer; 2-Positioning fixture; 201-Winding mold; 201-1-Base; 201-2-Winding base column; 201-3-Limiting plate; 201-4-Limiting clamp; 201-5-Fixing component; 202-Positioning pad. Detailed Implementation

[0024] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0025] This invention provides a high-field multilayer pure coil cos A bidirectional scanning magnet is distributed, which contains no iron core and is only excited by water-cooled coils; to achieve a high field, a multi-layered nested coil structure is used; bidirectional scanning is achieved by sequentially nesting horizontal and vertical coils; to improve the uniformity of the target area and range, the conductors in the excitation winding are arranged at a cosine angle. distributed.

[0026] like Figures 1 to 3 As shown, the high-field multilayer pure coil cosine provided by this invention Distributed bidirectional scanning magnets, including: positioning fixture 2 (see Figure 6 and Figure 7 ); Coil layer sleeve 1, each coil layer sleeve 1 is formed by a pair of coil layers 101, and each coil layer 101 is formed by the positioning fixture 2 by winding the wire in a U-shape to form a semi-cylindrical surface (see Figure 4 The two ends of the conductor extend into the same semi-cylindrical surface, and the two semi-cylindrical surfaces meet to form a cylindrical structure. Its three-dimensional model is as follows: Figure 5 As shown.

[0027] In the above embodiments, preferably, as follows: Figure 1 As shown, the coil layer 1 is a single layer, and the single coil layer is formed by a pair of coil layers 101 arranged in the X direction.

[0028] In the above embodiments, preferably, as follows: Figure 2 As shown, the coil layer sleeve 1 has two layers. The first layer of the coil layer sleeve 1 is formed by a pair of coil layers 101 arranged in the X direction; the second layer of the coil layer sleeve 1 is formed by a pair of coil layers 101 arranged in the Y direction; the second layer of the coil layer sleeve 1 is sleeved outside the first layer of the coil layer sleeve 1.

[0029] In the above embodiments, preferably, the coil layer sleeve 1 is multi-layered, and several coil layer sleeves 1 are nested alternately in the winding direction according to the XYYXYXXY pattern; the mating surfaces of a pair of semi-cylindrical surfaces on adjacent coil layer sleeves 1 are perpendicular to each other.

[0030] It should be noted that in the XYYXYXXY pattern described in this invention, X refers to a coil layer enclosed by a pair of coil layers arranged in the X direction; Y refers to a coil layer enclosed by a pair of coil layers arranged in the Y direction.

[0031] In this configuration, the radius and number of turns of the X-direction coil are always smaller than those of the Y-direction coil in the next layer. This results in a significantly smaller total inductance for the X-direction coil compared to the Y-direction coil. Traditional XY-type power supplies would require two different specifications, and the inductor voltage of the Y-direction power supply would be excessively high. By using a nested XYYXYXXY type configuration, the inductance will be between that of the XYXY type X or Y-direction coils, allowing the use of the same excitation power supply specification, and with a lower inductor voltage than the former Y-direction power supply.

[0032] In the above embodiments, preferably, the coil layer 101 has a double-layer structure.

[0033] In the above embodiments, preferably, copper busbar connectors are connected to both ends of the conductor.

[0034] In the above embodiments, preferably, the positioning fixture 2 includes a winding mold 201 and a positioning pad 202. The winding mold 201 is used to wind the coil layer 101, and the positioning pad 202 is used to isolate adjacent wires on the coil layer 101 to determine the position of the wires.

[0035] In the above embodiments, preferably, as follows: Figure 6 As shown, the winding mold 201 includes: a base 201-1, a winding base post 201-2, a limiting plate 201-3, a limiting clamp 201-4, and a fixing member 201-5; the winding base post 201-2 is disposed on the upper surface of the base 201-1 to form a protruding structure; the limiting plate 201-3 is disposed on the top of the winding base post 201-2 and is fixed to the base 201-1 by a plurality of fixing members 201-5; The two limiting clamps 201-4 are respectively sleeved on the winding base post 201-2 and fixed to the base 201-1, used to limit the winding coil in the height direction. The process of winding the coil using the winding mold 201 is as follows: Figure 8 As shown.

[0036] This invention also provides a high-field multilayer pure coil cos The method for using a distributed bidirectional scanning magnet includes the following steps: like Figure 1 As shown, a single-layer unidirectional magnet with a single coil layer can achieve scanning of the magnetic field in the Y direction and the X direction, or scanning of the magnetic field in the X direction and the Y direction. like Figure 2 and Figure 3 As shown in (b), a multi-layer bidirectional magnet with two or more coil layers can achieve high-field bidirectional scanning.

[0037] In the above embodiments, preferably, If a magnetic field is achieved in the Y direction and scanning is performed in the X direction, the angular distribution of the conductor conforms to... ; If a magnetic field is achieved in the X direction and scanning is performed in the Y direction, the conductor distribution should conform to... ; Where N is the total number of conductors in the corresponding 1 / 4 quadrant; i is the conductor number; .

[0038] It should be noted that: Figure 1 This is a single-layer, unidirectional two-dimensional model diagram, capable of realizing the magnetic field in the Y direction and scanning in the X direction. The angular distribution of each conductor conforms to... ,by Figure 1 For example, N=6, which is the total number of wires in the 1 / 4 quadrant of this layer, and i=3 is the third wire; if a magnetic field is achieved in the X direction and scanning is performed in the Y direction, the wire distribution conforms to... . Figure 2 This illustrates a single-layer bidirectional scanning 2D model. High-field bidirectional scanning is achieved by nesting the XYYXYXXY method sequentially. (Example...) Figure 3 As shown in (b).

[0039] Figure 5 This diagram illustrates a 3D model of a unidirectional 4-layer and bidirectional 8-layer scanning magnet. The ends employ a close-packed structure, which is the simplest to fabricate. The uniformity of the integrated magnetic field can be adjusted by the position of the end conductors. Multi-layered structures are necessary to achieve high fields, but as the radius increases, the contribution of the outer conductors to the central magnetic field gradually decreases. The actual number of layers needs to be calculated using simulation based on the aperture and the target magnetic field. In this embodiment, the aperture is 60mm, and the highest magnetic field is 6kGauss. Furthermore, cooling for this type of multi-layered structure requires special attention. Each layer typically has two cooling water channels. To achieve effective cooling, the wire gauge of each layer needs to be calculated. In this example, the water-cooled wire specifications and hydroelectric parameters are shown in Tables 1-4. I, L, R, U, P, Φ, a, V, Qm, ΔT, Phm, n, J, and Cu represent the coil current, conductor length, voltage, DC power, conductor aperture, side length of the square copper wire, water velocity, flow rate, number of water channels, and weight of the Cu wire, respectively. Table 1. Wire gauge and total inductance of each layer in traditional XYXY type layout.

[0040] Table 2 X / Y parameters under traditional XYXY arrangement

[0041] Table 3. Wire gauge and total inductance of each layer in the XYYXYXXY type layout of this invention.

[0042] Table 4. X / Y Direction Parameters for XYYXYXXY Type Layout

[0043] The conductors in this invention have a special positional distribution and a multi-layered structure. Their positional accuracy is directly related to the uniformity of the magnetic field. To achieve high-precision positioning that is easy to implement, the design is as follows: Figure 6-8 The winding mold and positioning pads shown are made of Peek material (3D printed). After the single-layer winding is manufactured, the layers are nested together with the positioning pads, and then the whole assembly is cast. The positioning pads ensure the positional accuracy of individual wires, and the winding mold ensures the concentricity of each layer of coils in the overall assembly.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-field multi-layer pure coil cos A distributed two-way scanning magnet characterized in that, The application relates to a coil layer set and a positioning tool. The coil layer set is formed by a pair of coil layers, each of which is formed by a wire wound in a semicylindrical shape by the positioning tool, and the two ends of the wire extend from the same end of the semicylindrical shape, and the pair of semicylindrical shapes are connected to form a cylindrical structure. The coil layer set is one layer, and the coil layer set of the one layer is formed by a pair of X-direction coil layers.

2. The high-field multi-layer pure coil cos A distributed two-way scanning magnet characterized by The coil layer set is two layers, the coil layer set of the first layer is formed by a pair of X-direction coil layers, the coil layer set of the second layer is formed by a pair of Y-direction coil layers, and the coil layer set of the second layer is sleeved outside the coil layer set of the first layer.

3. The high-field multi-layer pure coil cos A distributed two-way scanning magnet characterized by The coil layer set is multiple layers, and the coil layer sets are alternately nested in the winding direction according to the rule of XYYXYXXY.

4. The high-field multi-layer pure coil cos A distributed two-way scanning magnet characterized by The connecting surfaces of the pair of semicylindrical shapes on adjacent coil layer sets are perpendicular to each other. The coil layer is a double-layer structure.

5. The high-field multi-layer pure coil cos according to claim 1 A distributed two-way scanning magnet characterized by The two ends of the wire are respectively connected with copper bar joints.

6. The high-field multi-layer pure coil cos of claim 1 A distributed two-way scanning magnet characterized by The positioning tool comprises a winding die and a position cushion block, the winding die is used for winding the coil layer, and the position cushion block is used for isolating adjacent wires on the coil layer to determine the wire position.

7. The high-field multi-layer pure coil cos of claim 1 A distributed two-way scanning magnet characterized by The winding die comprises a base, a winding base column, a limiting plate, a limiting hoop and a fixing piece.

8. The high-field multi-layer pure coil cos of claim 6 A distributed two-way scanning magnet characterized by The winding base column is arranged on the upper surface of the base to form a convex structure. The limiting plate is arranged on the top of the winding base column and is fixed with the base through the fixing pieces. Two limiting hoops are respectively sleeved outside the winding base column and are fixed with the base to limit the wound coil in the height direction. The application relates to a coil layer set and a positioning tool.

9. A high-field multi-layer pure coil cos based on any one of claims 1 to 8 Method of using a distributed bi-directional scanning magnet, characterized in that The single-layer single-direction magnet with the one-layer coil layer set can realize Y-direction magnetic field and X-direction scanning or X-direction magnetic field and Y-direction scanning. The multi-layer double-direction magnet with the two-layer or more coil layer sets can realize high-field double-direction scanning.

10. The use method according to claim 9, characterized in that, ​ If the Y direction magnetic field is implemented, the X direction scanning, the wire angle distribution conforms to ; If the X-direction magnetic field is implemented, the Y-direction scanning, and the wire distribution conforms to ; Wherein, N is the total number of conductors in the layer 1 / 4 quadrant; i is the serial number of the conductor; .

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