Quadrupole magnet and particle accelerator

Abstract

The utility model relates to the technical field of particle accelerators, in particular to a quadrupole magnet and a particle accelerator, the quadrupole magnet comprises a first frame, a second frame and four independent winding coils wound between the first frame and the second frame, the first frame and the second frame are symmetrically closed frames and are arranged in parallel at intervals, and the first frame and the second frame are parallel to each other. The particle beams are rotationally symmetrical around a particle beam flow channel positioned in the centers of the two frames; each independent winding coil comprises two transverse bending sections and two longitudinal acting sections, an interval space is formed between the two longitudinal acting sections of the same independent winding coil, and at least one longitudinal acting section of the other independent winding coil is arranged in the interval space; and the geometric length of the transverse bending section is expanded by increasing the extension path. Through the rotational symmetric layout of the symmetric closed frame, the extending winding path of the transverse bending section and the collaborative filling design of the multi-coil interval space, the defect of a traditional acute angle bending process is avoided, and meanwhile the limited space is utilized to the maximum extent.

Description

Technical Field

[0001] This utility model relates to the field of particle accelerator technology, specifically to a quadrupole magnet and a particle accelerator. Background Technology

[0002] In the field of medical devices (such as magnetic resonance imaging systems and proton therapy accelerators), quadrupole magnets are core components for beam focusing and precise particle trajectory control. These devices place extremely high demands on the magnet's compact size, magnetic field uniformity, and operational reliability. Especially in tumor radiotherapy, even minute deviations in the magnetic field gradient can lead to beam positioning errors, directly impacting treatment effectiveness and patient safety. However, the coil design of traditional quadrupole magnets faces significant challenges.

[0003] In traditional coil winding processes, to accommodate more turns in a small space, multiple sharp-angle bends (with inward bends at the inner ends of the bends) are often used to achieve a compact layout. However, this design has the following problems:

[0004] 1. Limited turns density: Sharp-angle bends require a bend allowance (such as a bend radius ≥ 3 times the strip thickness), which greatly reduces the actual usable space in the innermost layer of the coil, thus limiting the turns density.

[0005] 2. Brittleness risk of superconducting materials: Among superconducting materials, high-temperature superconducting tapes (such as REBCO) are essentially brittle ceramics. Sharp-angle bending can cause internal microcracks, leading to a significant degradation of the critical current density, or even local fracture failure.

[0006] Especially in the field of medical equipment, it is necessary to achieve a high-intensity magnetic field (gradient ≥100 T / m) in a limited space (such as the magnet aperture of a proton therapy rotating gantry ≤30cm). However, traditional designs are limited by bending constraints, making it difficult to balance compactness and high performance. Reducing the number of turns to shrink the volume will sacrifice the magnetic field strength; if the number of turns is increased, the magnet size needs to be enlarged, which cannot adapt to the space constraints of medical equipment.

[0007] Currently, the mainstream solutions to the above problems include:

[0008] Multilayer thin strip winding: Using multiple thin superconducting strips to replace a single thick strip can partially alleviate bending stress, but the interlayer contact resistance increases, leading to increased current loss.

[0009] Flexible substrate technology: Attaching a flexible metal substrate to the back of a superconducting tape can improve bending toughness, but the additional thickness introduced by the substrate further compresses the winding space, and the number of turns density will actually decrease.

[0010] In summary, achieving high-turn-density winding of superconducting coils within a limited space while avoiding material damage caused by sharp-angle bending has become a key bottleneck in the design of medical-grade quadrupole magnets. A novel winding structure is urgently needed that maximizes the use of limited space while adapting to the mechanical properties of superconducting materials, ensuring a dual improvement in magnetic field gradient and operational reliability. Utility Model Content

[0011] (I) The technical problem to be solved by this utility model is that in the existing quadrupole magnet design, the sharp angle bending of the coil leads to damage to the superconducting material and low utilization of the winding space. Especially in the miniaturization scenario of medical equipment, it is difficult to balance high turn density and magnetic field uniformity, resulting in insufficient magnetic field gradient and poor material reliability.

[0012] (II) Technical Solution

[0013] To address the aforementioned technical problems, one embodiment of this utility model provides a quadrupole magnet, comprising a first frame, a second frame, and four independent winding coils wound between the two frames.

[0014] The first frame and the second frame are symmetrical closed frames, parallel and spaced apart, and rotate symmetrical about the particle beam channel located at the center of the two frames.

[0015] Each individual winding coil includes:

[0016] Two transversely bent sections are respectively extended, wound, and fixed to the corresponding edges of the first and second frames;

[0017] Two longitudinal action sections, spanning between the transverse bending sections and extending along the axial direction of the central particle beam channel, are used to generate a quadrupole magnetic field.

[0018] In this configuration, a space is formed between two longitudinal working segments of the same independent winding coil, and at least one longitudinal working segment of another independent winding coil is provided in the space, so that the geometric length of the transverse bending segment is extended by increasing the extension path.

[0019] The rotational symmetry of the symmetrical closed frame ensures that the radial gradient of the quadrupole magnetic field is strictly symmetrical, eliminating the magnetic field distortion caused by geometric deviations in traditional asymmetrical frames, and providing a basis for the precise positioning of particle beams in medical scenarios. By extending the lateral bending segment along the edge of the frame by a preset distance before bending, the straight extension length of the bending segment is significantly increased, and the sharpness of the bending angle under limited length is reduced. This avoids the risk of microcracks or fractures caused by multiple sharp-angle bends in superconducting materials, and improves the overall magnetic field strength in a compact structure.

[0020] The synergistic effect of the above-mentioned technical features enables this invention to meet the miniaturization requirements of medical devices, avoiding mechanical damage and performance degradation of superconducting materials while achieving high gradient magnetic field output, providing a highly reliable magnet solution for applications such as precision radiotherapy for tumors.

[0021] According to one embodiment of the present invention, the symmetrical closed frame is a square frame;

[0022] The longitudinal action segments of the four independent winding coils are arranged along the four sides of the square frame, with two longitudinal action segments arranged on each side, and the two longitudinal action segments belong to different independent winding coils.

[0023] The longitudinal action segments of the opposing sides are symmetrically arranged in geometric position and current direction to generate a symmetrical quadrupole magnetic field in the central particle beam channel.

[0024] By utilizing the geometric symmetry of the square frame, the gradients of the quadrupole magnetic field in orthogonal directions (such as the X and Y axes) are strictly complementary, which not only eliminates the uneven magnetic field distribution caused by curvature differences in traditional circular or polygonal frames, but also provides a benchmark for the linear arrangement of the longitudinal action segments. By symmetrically arranging the longitudinal action segments on the opposing sides in terms of geometric position and current direction (such as the magnetic field polarities of the upper and lower side action segments being opposite, and the same for the left and right sides), a centrally symmetrical quadrupole magnetic field is generated, which effectively suppresses beam deflection or divergence caused by current path deviation. By distributing two longitudinal action segments belonging to different coils on each side, the superposition and synergy of multiple coil magnetic fields are achieved within a limited space.

[0025] It is particularly well-suited to the miniaturization needs of medical equipment. For example, in the rotating gantry of a proton therapy device, the compact layout of the square frame and the strictly symmetrical magnetic field distribution enable high-precision beam control within a limited installation space, providing a reliable guarantee for the precise irradiation of the tumor target area.

[0026] According to one embodiment of the present invention, the two longitudinal working segments of each independent winding coil are respectively arranged on two adjacent sides of the square frame;

[0027] Within the space between two longitudinal working sections of the same independent winding coil, there are two other longitudinal working sections of different independent winding coils.

[0028] By arranging the longitudinal action segments on adjacent sides, the transverse bending segment of the same coil only needs to be bent once along the edge of the frame to complete the bridging, which significantly reduces the number of bends and maximizes the straight extension length of the bending segment. This avoids stress concentration in the superconducting material caused by multiple bends. By filling the space between the two other coils with the longitudinal action segments of different coils in the same coil, the straight path is extended to improve the utilization rate of the winding space, and the overall structure volume is minimized.

[0029] This setup is particularly crucial in situations requiring high turns in small spaces: the synergy of adjacent side layouts effectively increases the straight length of the bends, thereby achieving the dual goals of high-density winding of superconducting coils and high-intensity magnetic field output within the limited installation space of medical equipment.

[0030] According to one embodiment of the present invention, both the first frame and the second frame are provided with winding grooves, the contour of which is adapted to the winding path of the transverse bending segment, in order to constrain the extension direction of the transverse bending segment and expand the bending space.

[0031] The winding groove has an opening on the side facing the opposite frame, and the axis of the opening is parallel to the axis of the central particle beam channel, which is used to extend the longitudinal action section from one side frame to the opposite side frame.

[0032] By precisely matching the contour of the winding groove with the geometry of the transverse bending section, the extension direction of the bending section is constrained and its winding space is expanded, thus avoiding the risk of inter-turn misalignment or short circuit caused by path deviation in traditional free winding. By setting the axis of the opening parallel to the axis of the central particle beam channel, it is ensured that the path of the longitudinal action section is strictly aligned when extending from one side frame to the other side frame, which not only eliminates the angular deviation in the bridging process, but also maintains the axisymmetry of the magnetic field distribution through straight extension, thereby achieving high-precision magnetic field gradient control in a limited space.

[0033] According to one embodiment of the present invention, each side of the first frame and the second frame is provided with a winding groove, and each frame has a total of four winding grooves, including two inner winding grooves and two outer winding grooves.

[0034] The inner winding groove is provided on the inner edge of two adjacent sides of the square frame, and the outer winding groove is provided on the outer edge of the other two adjacent sides;

[0035] Only one independent winding coil is wound in each winding slot, so that the transverse bending section in the inner winding slot is isolated from the transverse bending section in the outer winding slot.

[0036] By layering the winding slots on the inner and outer edges of the frame and limiting each slot to a lateral bend where only a single coil is wound, the isolation of the coil layout is further optimized. This avoids the risk of physical contact or short circuit caused by path intersections in traditional winding, maximizes the use of the frame edge space, reduces the local thickness increase caused by the original cross winding, improves the winding density, and significantly reduces the performance degradation of the material caused by complex bending.

[0037] According to one embodiment of the present invention, the winding groove at the opening is inclined relative to the side of the square frame, and the inclination angle is adapted to the thickness of the frame and the spacing between the inner and outer winding grooves.

[0038] The inclined arrangement ensures that the longitudinal action sections extending from the openings of the inner and outer winding grooves on the same frame edge are in the same plane, and the plane is parallel to the axis of the central particle beam channel.

[0039] The inclined design of the winding groove compensates for the height difference of the longitudinal action section caused by the frame thickness and the spacing between the inner and outer winding grooves. This ensures that the longitudinal action sections extending from the openings of the inner and outer winding grooves on the same frame edge are in the same plane, eliminating the magnetic field gradient tilt caused by structural misalignment in traditional designs. By setting this plane parallel to the axis of the central particle beam channel, the magnetic field distribution of the longitudinal action section is ensured to be strictly symmetrical along the axis, avoiding beam divergence or trajectory deviation caused by planar deviation, thus providing a highly reliable guarantee for the precise irradiation of the tumor target area.

[0040] According to one embodiment of the present invention, the frame further includes a sealing plate, which covers the opening side of the winding groove and is used to close the groove and limit the transverse bending section.

[0041] By adding a sealing plate covering the opening side of the winding slot, the stability and structural reliability of the coil winding are further ensured. The sealing plate isolates the coil from external physical corrosion by enclosing the slot, and its inner limiting structure, adapted to the contour of the winding slot, constrains the displacement of the lateral bending section, preventing loosening of the winding due to vibration or electromagnetic forces. This maintains the accuracy and consistency of the magnetic field distribution during long-term operation. This design is particularly important under the harsh operating conditions of medical equipment, providing double protection for the high reliability of the magnet.

[0042] According to one embodiment of the present invention, the sidewall of the bend in the winding groove is an arc-shaped sidewall, which smoothly transitions the bending path of the transverse bending segment.

[0043] By designing the sidewall of the bending section of the winding groove as an arc shape, the bending path of the transverse bending section is smoothly transitioned. This not only eliminates the stress concentration damage to the superconducting material caused by traditional sharp-angle bending, but also optimizes the winding accuracy of the bending section through continuous curvature, providing a stable guarantee for high-precision beam control in medical scenarios.

[0044] According to one embodiment of the present invention, the winding coil is a high-temperature superconducting coil.

[0045] By employing high-temperature superconducting materials to wind the coils, the energy efficiency and operational stability of the magnet are further optimized. The zero-resistance characteristic of the high-temperature superconducting coils enables lossless current transmission at liquid nitrogen temperatures (77 K), significantly reducing the complexity and energy consumption of the cooling system. Simultaneously, its high critical current density supports the generation of a high-intensity magnetic field within a compact space. Combined with the extended bending path and arc-shaped winding groove design of this invention, the brittleness of the high-temperature superconducting materials is effectively avoided. Its synergistic design with the framework and winding process of this invention provides a highly reliable and miniaturized magnet solution for precision tumor treatment.

[0046] Another example of this invention provides a particle accelerator comprising the quadrupole magnet described in any of the preceding claims.

[0047] By integrating the high-gradient, highly uniform, and miniaturized quadrupole magnet, this particle accelerator enables more precise particle beam control in medical applications such as proton therapy, adapts to the space constraints of hospital machine rooms, and provides efficient technical support for precise clinical radiotherapy.

[0048] (III) Beneficial effects of this utility model: This utility model, through the rotational symmetry layout of the symmetrical closed frame, the extended winding path of the transverse bending section, and the collaborative filling design of the space between multiple coils, avoids the defects of the traditional acute angle bending process, maximizes the use of limited space, and realizes high-density winding and high-precision magnetic field control of superconducting coils. Attached Figure Description

[0049] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0050] Figure 1 This is a schematic diagram of the three-dimensional structure of the original winding coil;

[0051] Figure 2 A three-dimensional structural diagram of the winding coil with a circular frame, provided for one embodiment of this utility model;

[0052] Figure 3 A schematic diagram of the three-dimensional structure of a quadrupole magnet with a square frame is provided for one embodiment of this utility model;

[0053] Figure 4 A schematic diagram of the three-dimensional structure of a quadrupole magnet in an unsealed state with a square frame, as provided in one embodiment of this utility model;

[0054] Figure 5 A three-dimensional structural diagram of the winding coil with a square frame, provided for one embodiment of the present utility model;

[0055] Figure 6 for Figure 5 A three-dimensional structural diagram from another perspective;

[0056] Figure 7 A three-dimensional structural diagram of an independent winding coil with a square frame, provided for one embodiment of this utility model;

[0057] Figure 8 A three-dimensional structural diagram of a square frame provided in one embodiment of the present utility model;

[0058] Figure 9 for Figure 8 A three-dimensional structural diagram from another perspective;

[0059] Figure 10 for Figure 8 The main view;

[0060] Figure 11 for Figure 8 The left view.

[0061] Icons: 11. First frame; 12. Second frame; 13. Winding groove; 131. Opening; 132. Arc-shaped sidewall; 14. Sealing plate; 2. Winding coil; 21. Lateral bending section; 22. Longitudinal action section; 3. Central particle beam channel. Detailed Implementation

[0062] To better understand the above-mentioned objectives, features, and advantages of this utility model, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. Unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model. Specific implementation examples:

[0064] like Figure 1 As shown, in the prior art, the coil winding method of a quadrupole magnet is as follows: Figure 1As shown, the longitudinal action segments 22 are arranged closely adjacent to each other on the edge of the frame, which severely compresses the winding space of the transverse bending segments 21. Specifically, because the spacing between the adjacent longitudinal action segments 22 is too small, the transverse bending segments 21 are forced to use multiple acute-angle bends (such as right angles or acute angles), and the bending radius usually needs to be more than three times the thickness of the strip. Such acute-angle bends not only cause stress concentration inside the superconducting material, leading to microcracks or even fracture (critical current density degradation rate exceeds 30%), but also reduce the innermost winding width of the coil to less than 50% of the design value due to the space occupied by the bending allowance, limiting the number of turns per layer to less than 8 turns, and making it difficult to exceed 80 T / m in the magnetic field gradient.

[0065] like Figures 3 to 11 As shown, this embodiment provides a quadrupole magnet, which includes a first frame 11, a second frame 12, and four independent winding coils 2 wound between the two frames. The first frame 11 and the second frame 12 are symmetrical closed frames arranged in parallel intervals, and are rotationally symmetrical around the central particle beam channel 3. The symmetrical closed shape of the frame can be a circular, square, or elliptical centrosymmetric structure. In this embodiment, a square frame is preferred, as its geometric symmetry not only facilitates manufacturing but also ensures a strictly complementary distribution of the magnetic field gradient in the orthogonal directions, avoiding magnetic field distortion caused by uneven curvature. Each independent winding coil 2 is made of a high-temperature superconducting material (such as rare-earth barium copper oxide REBCO tape), which exhibits a high critical current density (and zero resistance) in the liquid nitrogen temperature range (77K), providing a basis for the generation of a high-intensity magnetic field in a compact space.

[0066] like Figures 4 to 7As shown, each independent winding coil 2 includes two transverse bending sections 21 and two longitudinal action sections 22. The transverse bending sections 21 are wound along the edges of the frame, for example, between the upper edge and the left side edge of the first frame 11, through a single large curvature bend (bending radius ≥ 10 mm) wound on the two adjacent edges of the first frame 11. This extended winding path significantly increases the straight length of the bending sections, making the stress distribution of the superconducting tape at the bend more uniform, thereby reducing the critical current degradation rate to less than 20% of that of conventional acute-angle bends. The longitudinal action sections 22 span between the transverse bending sections 21, extend along the axial direction of the central particle beam channel 3, and directly act on the particle beam to generate a quadrupole magnetic field. Its arrangement is precisely designed: the two longitudinal action segments 22 of the same coil are located on two adjacent sides of the square frame (such as the upper and right sides of coil A), and the space between them is filled with the longitudinal action segments 22 of two other different coils (such as coil B and coil C). The superposition and complementarity of magnetic field components are achieved through staggered layout. For example, the longitudinal action segment 22 of coil B extends along the upper and left sides, and the longitudinal action segment 22 of coil C extends along the lower and right sides, forming a complementary magnetic field distribution. This design not only maximizes the use of the space on the side of the frame, but also increases the number of turns in a single layer to more than 6 turns.

[0067] The longitudinal action segments 22 of the four independent winding coils 2 are arranged along the four sides of the square frame, with two longitudinal action segments 22 belonging to different coils on each side. For example, one longitudinal action segment 22 of coils A and B is arranged on the upper side, with the current direction of both being the same; one longitudinal action segment 22 of coils C and D is arranged on the lower side, with the current direction being the same as the upper side. The same applies to the left and right sides, but the current direction is opposite. Through this symmetrical arrangement of the geometric positions of the opposing sides with the current direction, a strictly symmetrical quadrupole magnetic field distribution is formed within the central particle beam channel 3. This design not only suppresses beam divergence caused by current path deviation, but also increases the magnetic field gradient in the central region to over 150 T / m through the superposition of the magnetic fields of multiple coils in the space, while controlling the uniformity error to within 3%, meeting the millimeter-level accuracy requirements for beam target area positioning in proton therapy.

[0068] Furthermore, such as Figures 8 to 11As shown, each side of the first frame 11 and the second frame 12 is provided with a winding groove 13. Each frame has four winding grooves 13, including two inner winding grooves 13 and two outer winding grooves 13, which are respectively located on the inner and outer edges of the side. The inner winding grooves 13 are located on the inner side of two adjacent sides of the square frame (e.g., the inner edges of the upper and right sides), close to the central particle beam channel 3; the outer winding grooves 13 are located on the outer side of the other two adjacent sides (e.g., the outer edges of the upper and left sides), away from the beam channel. The contour of the winding groove 13 is precisely matched with the geometry of the transverse bending section 21: its U-shaped cross-section width is slightly larger than the width of the superconducting strip (e.g., when the strip width is 4mm, the groove width is 4.8mm), the depth is [not specified], and the inner sidewall is a smooth arc shape to ensure that the transverse bending section 21 is uniformly stressed after being embedded, and to avoid damage to the strip edge due to groove wall friction.

[0069] The winding groove 13 has an opening 131 on the side facing the opposite frame. The axis of the opening 131 is strictly parallel to the axis of the central particle beam channel 3, and its width matches the cross-section of the winding groove 13. Through the design of the opening 131, the longitudinal action section 22 extends from the winding groove 13 of one frame to the corresponding groove of the opposite frame. For example, the longitudinal action section 22 of coil A extends from the opening 131 of the winding groove 13 on the upper side of the first frame 11 to the winding groove 13 on the upper side of the second frame 12. The straightness deviation of its extension path is controlled within ±0.1mm to ensure the axial symmetry of the magnetic field distribution.

[0070] Isolation design of layered winding groove 13

[0071] The distance between the inner winding slot 13 and the outer winding slot 13 is 10mm (set according to the frame thickness and winding requirements), which physically isolates the transverse bending sections 21 of different coils from contacting each other. Only the transverse bending section 21 of a single coil is wound in each winding slot 13, and the slots are filled with insulating material (such as polyimide film) to further block electromagnetic interference.

[0072] Planar compensation of inclined winding groove 13

[0073] like Figure 4 and Figure 8 As shown, the winding groove 13 at the opening 131 is inclined relative to the edge of the square frame. The inclination angle is calculated using the frame thickness and the distance between the inner and outer winding grooves 13. This inclined design ensures that the longitudinal action sections 22 extending from the opening 131 of the inner and outer winding grooves 13 on the same frame edge are in the same plane, and this plane is parallel to the axis of the central particle beam channel 3. Figure 8For example, the longitudinal action section 22 of the inner winding groove 13 extends downward at 15°, and the path of the outer winding groove 13 extends upward at 15°. After bridging, the two are on the same horizontal plane, eliminating the height difference caused by the frame thickness and ensuring that the magnetic field gradient direction is strictly distributed along the axial direction.

[0074] The curved sidewall 132 and the sealing plate 14 limit the movement.

[0075] like Figure 3 As shown, the sidewall of the bend in the winding groove 13 is designed with an arc shape (radius ≥ 10 mm), smoothly transitioning the bending path of the transverse bending section 21 and avoiding stress concentration caused by sharp-angle bends. For example, the transverse bending section 21 naturally turns along the arc-shaped sidewall 132 at the bend, increasing the bending radius to more than 3 times that of the traditional design, and the critical current degradation rate is ≤ 5%. The frame also includes a sealing plate 14, which is fixed to the opening 131 of the winding groove 13 by bolts. The inner side of the sealing plate has a limiting protrusion (height 1 mm) that matches the U-shaped contour of the winding groove 13, and the displacement of the transverse bending section 21 after insertion is ≤ 0.2 mm. The sealing plate 14 is made of G10 glass fiber and coated with polytetrafluoroethylene (friction coefficient ≤ 0.1), which not only seals the groove (dustproof and moistureproof) but also ensures winding stability through the limiting structure, adapting to the high-frequency vibration environment of medical equipment (such as the rotation condition of a proton therapy gantry).

[0076] The quadrupole magnet in this embodiment is used in particle accelerators in the medical field (such as proton therapy systems). Its core function is to focus and guide charged particle beams (such as proton beams). The specific working principle is as follows:

[0077] Generation of quadrupole magnetic fields

[0078] By symmetrically arranging four independently wound coils 2 and controlling the current direction, a strictly complementary quadrupole magnetic field is generated within the central particle beam channel 3. (Using a square frame as an example:)

[0079] Current direction rule: The longitudinal action segments 22 of adjacent sides have opposite current directions, forming a magnetic field gradient distribution in orthogonal directions.

[0080] Magnetic field gradient effect: When a particle beam passes through a magnetic field, the laterally deflected particles are subjected to the magnetic field gradient force, thereby achieving beam focusing and divergence angle suppression.

[0081] Coil layout and magnetic field superposition

[0082] Coordinated arrangement of longitudinal action segments 22: Two longitudinal action segments 22 of the same coil are placed on adjacent sides (such as the upper side and the right side), and the magnetic field components generated by them are superimposed in the central region to enhance the local magnetic field strength;

[0083] Space filling effect: The space is filled with the working section of other coils. Through the complementarity of the magnetic field components of multiple coils, the magnetic field blind zone is eliminated and the gradient is ensured to be linearly distributed.

[0084] Structural innovation ensures magnetic field accuracy

[0085] Guiding and isolation of winding slot 13: The physical isolation design of inner and outer winding slot 13 avoids the current path crossing of different coils and suppresses electromagnetic coupling (coupling degree ≤5%).

[0086] Planar consistency of inclined opening 131: By setting the inclined position of the winding groove 13, it is ensured that the longitudinal action section 22 is in the same plane after bridging, and this plane is parallel to the beam channel axis, avoiding the tilting of the magnetic field direction due to structural misalignment.

[0087] Stability control of sealing plate 14: Sealing plate 14 constrains the displacement of the transverse bending section 21 through a limiting structure (displacement ≤0.2mm under vibration), ensuring the stability of the magnetic field distribution during long-term operation of the coil.

[0088] Energy efficiency advantages of high-temperature superconducting materials

[0089] High-temperature superconducting coils (such as REBCO tape) achieve zero-resistance operation in the liquid nitrogen temperature range (77 K), increasing magnetic field generation efficiency to more than three times that of conventional conductors. Combined with a single large-curvature bending process (bending radius ≥10 mm), its critical current degradation rate is ≤5%, maintaining consistent magnetic field output even in intermittent operation modes of medical equipment (such as fractional proton irradiation).

[0090] Workflow Example (Proton Therapy Scenario)

[0091] Beam injection: The proton beam is injected from the accelerator into the central particle beam channel 3;

[0092] Magnetic field focusing: The gradient force of the quadrupole magnetic field acts on the proton beam, causing the laterally deflected protons to converge toward the center of the channel, compressing the divergence angle to less than 0.1 milliradians;

[0093] Target localization: The focused beam is guided by a subsequent magnet to accurately irradiate the tumor target area (localization error ≤1mm).

[0094] This embodiment achieves high-density layout, high-precision magnetic field control, and high-reliability operation of superconducting coils in a medical-grade miniaturized setting through a symmetrical frame, extended winding path, and layered slot design, providing core technical support for precision radiotherapy.

[0095] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A quadrupole magnet, comprising a first frame, a second frame, and four independent winding coils wound between the two frames, characterized in that: The first frame and the second frame are symmetrical closed frames, parallel and spaced apart, and rotate symmetrical about the particle beam channel located at the center of the two frames. Each individual winding coil includes: Two transversely bent sections are respectively extended, wound, and fixed to the corresponding edges of the first and second frames; Two longitudinal action sections, spanning between the transverse bending sections and extending along the axial direction of the central particle beam channel, are used to generate a quadrupole magnetic field. In this configuration, a space is formed between two longitudinal working segments of the same independent winding coil, and at least one longitudinal working segment of another independent winding coil is provided in the space, so that the geometric length of the transverse bending segment is extended by increasing the extension path.

2. The quadrupole magnet according to claim 1, characterized in that, The symmetrical closed frame is a square frame; The longitudinal action segments of the four independent winding coils are arranged along the four sides of the square frame, with two longitudinal action segments arranged on each side, and the two longitudinal action segments belong to different independent winding coils. The longitudinal action segments of the opposing sides are symmetrically arranged in geometric position and current direction to generate a symmetrical quadrupole magnetic field in the central particle beam channel.

3. The quadrupole magnet according to claim 2, characterized in that, The two longitudinal working segments of each independent winding coil are respectively arranged on two adjacent sides of the square frame; Within the space between two longitudinal working sections of the same independent winding coil, there are two other longitudinal working sections of different independent winding coils.

4. The quadrupole magnet according to claim 3, characterized in that, Both the first frame and the second frame are provided with winding grooves. The contour of the winding grooves is adapted to the winding path of the transverse bending segment, which is used to constrain the extension direction of the transverse bending segment and expand the bending space. The winding groove has an opening on the side facing the opposite frame, and the axis of the opening is parallel to the axis of the central particle beam channel, which is used to extend the longitudinal action section from one side frame to the opposite side frame.

5. The quadrupole magnet according to claim 4, characterized in that, Each edge of the first frame and the second frame is provided with a winding groove. Each frame has a total of four winding grooves, including two inner winding grooves and two outer winding grooves. The inner winding groove is provided on the inner edge of two adjacent sides of the square frame, and the outer winding groove is provided on the outer edge of the other two adjacent sides; Only one independent winding coil is wound in each winding slot, so that the transverse bending section in the inner winding slot is isolated from the transverse bending section in the outer winding slot.

6. The quadrupole magnet according to claim 5, characterized in that, The winding groove at the opening is inclined relative to the edge of the square frame, and the inclination angle is adapted to the thickness of the frame and the spacing between the inner and outer winding grooves. The inclined arrangement ensures that the longitudinal action sections extending from the openings of the inner and outer winding grooves on the same frame edge are in the same plane, and the plane is parallel to the axis of the central particle beam channel.

7. The quadrupole magnet according to claim 5, characterized in that, The frame also includes a sealing plate that covers the opening side of the winding groove to close the groove and limit the transverse bending section.

8. The quadrupole magnet according to claim 5, characterized in that, The sidewall at the bend of the winding groove is an arc-shaped sidewall, which smoothly transitions the bending path of the transverse bending section.

9. The quadrupole magnet according to any one of claims 1 to 8, characterized in that, The winding coil is a high-temperature superconducting coil.

10. A particle accelerator, characterized in that, Includes a quadrupole magnet as described in any one of claims 1 to 9, the quadrupole magnet being used for focusing and guiding a particle beam.

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