Spiral resonant cavity for superconducting cyclotron

Abstract

The invention relates to the technical field of superconducting cyclotrons, and discloses a spiral resonant cavity for a superconducting cyclotron, which comprises an upper resonant cavity body and a lower resonant cavity body, and the upper resonant cavity body is positioned right above the lower resonant cavity body; through distributed waterway design and structural optimization, the cooling system can effectively process heat generated in the accelerator; efficient heat dissipation of the system is ensured through design means such as a multi-directional cooling channel, an oxygen-free copper brazing pipeline and a double-path independent cooling pipe, excessive accumulation in a high-temperature area is avoided, and meanwhile the stability of equipment can be kept in long-time operation; the structure of the single inner rod is convenient for voltage distribution adjustment, the structure is simple and compact, and the processing complexity and the manufacturing cost are greatly reduced; a core component solution with high reliability and low operation and maintenance cost is provided for the superconducting cyclotron, and application efficiency upgrading in the fields of medical treatment, scientific research and the like is promoted.

Description

Technical Field

[0001] This invention relates to the field of superconducting cyclotron technology, and more specifically to a spiral resonant cavity for a superconducting cyclotron. Background Technology

[0002] Cyclotrons, with their high efficiency and compact design, are widely used in research fields such as medical diagnosis and treatment, material analysis and identification, material performance improvement, and nuclear physics experiments. The high-frequency system, as a key and complex subsystem of a superconducting cyclotron, affects the accelerator's stability and reliability. The high-frequency resonant cavity is a crucial component of this system, storing energy from the high-frequency power source, generating the radio frequency field required for accelerating charged particles, and providing the necessary electromagnetic field conditions for particle extraction from the central region. Its stability is directly related to the accelerator's operation. Typically, the design and structure of the high-frequency resonant cavity are primarily constrained by the design of the main magnet. Specifically, the shape and position of the resonant cavity are designed based on the particle cyclotron frequency and accelerating harmonic number, taking into account the space of the magnet valley region and the vacuum chamber boundary. The aim is to minimize power loss and improve the quality factor (Q) while meeting the voltage distribution requirements of the resonant frequency, achieving good structural strength and ease of engineering implementation. Due to differences in constraints such as resonant frequency, accelerating voltage distribution, and valley geometry, the structural designs of high-frequency resonant cavities vary considerably. To address the technical problems of existing high-frequency resonant cavities, such as complex mechanical structure, insufficient cooling efficiency, and poor maintenance convenience, this invention provides an innovative cavity structure design scheme. Summary of the Invention

[0003] This invention provides a spiral resonant cavity for a superconducting cyclotron accelerator, with a cooling system that effectively dissipates heat, prevents heat accumulation, and ensures long-term stable operation of the accelerator.

[0004] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: In a first aspect, a helical resonant cavity for a superconducting cyclotron accelerator is provided, comprising: the resonant cavity is composed of an upper resonant cavity and a lower resonant cavity, wherein the upper resonant cavity is located directly above the lower resonant cavity, and further comprising: Oxygen-free copper brazed tubing is fixed within grooves on the outer walls of the upper and lower resonant cavities; cooling channels are formed on the outer walls of the upper and lower resonant cavities; the accelerating electrode Dee plate is located between the upper and lower resonant cavities and is used to accelerate protons under the action of a high-frequency electric field; the central electrode is fixed inside the accelerating electrode Dee plate; a high-frequency spring is welded to the tail end of the accelerating electrode Dee plate and is elastically pressed against the opposite accelerating electrode Dee plate at the mid-plane of the upper and lower resonant cavities to achieve electrical continuity between the two accelerating electrode Dee plates and ensure stable transmission of high-frequency signals; a lower flange is fixed to the accelerating electrode Dee plate; and a single inner rod... Fixed above the lower flange and located within the upper and lower resonant cavity bodies; a microchannel, formed within the thin wall of the single inner rod; cooling water inlet and outlet, fixed above the single inner rod; cooling pipe, fixed above and below the accelerating electrode Dee plate and located within the single inner rod, used to directly absorb the heat deposited by the accelerating electrode Dee plate during proton acceleration; a capacitor tuning port, fixed on the upper resonant cavity body, used to achieve precise fine-tuning of the resonant frequency by adjusting the internal metal capacitor plate; an inductive coupling ring, fixed on the lower resonant cavity body, used to achieve impedance matching and power coupling between the resonant cavity and the external RF system; a coaxial feeder, fixed on the inductive coupling ring and located below the inductive coupling ring; The upper and lower resonant cavity bodies are three-step spiral structures, and the thickness of both the upper and lower resonant cavity bodies is 18mm. The inner cavities of the upper and lower resonant cavity bodies form a uniform electromagnetic field distribution channel. The cooling channel is arranged in a serpentine meandering pattern. The cooling pipes are arranged in dual independent paths.

[0005] Furthermore, the upper resonant cavity and the lower resonant cavity have a mirror-symmetrical structure.

[0006] Furthermore, the accelerating electrode Dee plate is a spiral-shaped oxygen-free copper component.

[0007] Furthermore, the high-frequency reed is made of oxygen-free copper and its surface is treated with silver plating.

[0008] Furthermore, the single inner rod has an oval hole shape and a hollow structure with a wall thickness of 10mm.

[0009] Furthermore, the metal capacitor plate inside the capacitor tuning port is adjustable, with an adjustment range of 0~100mm, and can achieve fine adjustment of the resonant frequency by ±0.5MHz.

[0010] Furthermore, the inductive coupling ring is adjustable and has a matching impedance of 50Ω.

[0011] Furthermore, the coaxial feeder is connected to an external radio frequency power source.

[0012] The above-described solution of the present invention has at least the following beneficial effects: Through distributed water circuit design and structural optimization, the cooling system can effectively handle the heat generated inside the accelerator. The design features such as multi-directional cooling channels, oxygen-free copper brazed pipes, and dual independent cooling pipes ensure efficient heat dissipation, avoid excessive heat accumulation in high-temperature areas, and maintain equipment stability during long-term operation. The single inner rod structure facilitates voltage distribution adjustment, and the simple and compact structure significantly reduces processing complexity and manufacturing costs. It provides a highly reliable and low-maintenance-cost core component solution for superconducting cyclotron accelerators, promoting the upgrading of application performance in fields such as medicine and scientific research. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the overall structure of a spiral resonant cavity for a superconducting cyclotron accelerator, provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of the structure of the accelerating electrode Dee plate of a helical resonant cavity for a superconducting cyclotron accelerator, provided in an embodiment of the present invention. Figure 3 A schematic diagram of a single inner rod and cross-section of a helical resonant cavity for a superconducting cyclotron accelerator is provided in an embodiment of the present invention. Figure 4 This is a schematic diagram of the structure of a cooling tube for a helical resonant cavity in a superconducting cyclotron accelerator, provided in an embodiment of the present invention. Figure 5 This is a schematic diagram of the structure of the capacitor tuning port of a spiral resonant cavity for a superconducting cyclotron accelerator, provided in an embodiment of the present invention.

[0014] Explanation of reference numerals in the attached figures: In the diagram: 1. Upper resonant cavity; 2. Lower resonant cavity; 3. Mid-plane; 4. Oxygen-free copper brazed pipe; 5. Cooling channel; 6. Accelerating electrode Dee plate; 7. Central electrode; 8. High-frequency reed; 9. Lower flange; 10. Single inner rod; 11. Microchannel; 12. Cooling water inlet and outlet; 13. Cooling pipe; 14. Capacitor tuning port; 15. Inductive coupling ring; 16. Coaxial feeder. Detailed Implementation

[0015] 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 may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0016] like Figures 1 to 5As shown, an embodiment of the present invention provides a helical resonant cavity for a superconducting cyclotron accelerator, comprising: the resonant cavity is composed of an upper resonant cavity 1 and a lower resonant cavity 2, wherein the upper resonant cavity 1 is located directly above the lower resonant cavity 2, and further comprising: Oxygen-free copper brazed pipe 4 is fixed above the upper resonant cavity 1 and inside the groove on the outer wall of the lower resonant cavity 2 to cover the high-loss areas inside the upper resonant cavity 1 and the lower resonant cavity 2; cooling channel 5 is opened on the outer wall of the upper resonant cavity 1 and the lower resonant cavity 2; accelerating electrode Dee plate 6 is located between the upper resonant cavity 1 and the lower resonant cavity 2; central electrode 7 is fixed inside the accelerating electrode Dee plate 6; high-frequency spring 8 is welded to the tail end of the accelerating electrode Dee plate 6, and is elastically pressed against the opposite accelerating electrode Dee plate 6 at the mid-plane 3 of the upper resonant cavity 1 and the lower resonant cavity 2; lower flange 9 is fixed to the accelerating electrode Dee plate 6. On the accelerating electrode Dee plate 6, an upper flange surface is provided on the side away from the accelerating electrode Dee plate 6; a single inner rod 10 is fixed above the lower flange surface 9 and located inside the upper resonant cavity 1 and the lower resonant cavity 2; a microchannel 11 is opened inside the thin wall of the single inner rod 10; a cooling water inlet / outlet 12 is fixed above the single inner rod 10; a cooling pipe 13 is fixed above and below the accelerating electrode Dee plate 6 and located inside the single inner rod 10; a capacitor tuning port 14 is fixed on the upper resonant cavity 1; an inductive coupling ring 15 is fixed on the lower resonant cavity 2; and a coaxial feed line 16 is fixed on the inductive coupling ring 15 and located below the inductive coupling ring 15.

[0017] Specifically, the upper resonant cavity 1 and the lower resonant cavity 2 have a mirror-symmetrical structure. The upper resonant cavity 1 and the lower resonant cavity 2 have a three-step spiral structure, and their outer contours are basically completely matched with the geometry of the valley region of the main magnet. The thickness of the upper resonant cavity 1 and the lower resonant cavity 2 is 18mm. The inner cavities of the upper resonant cavity 1 and the lower resonant cavity 2 form a uniform electromagnetic field distribution channel. The mid-plane 3 of the upper resonant cavity 1 and the lower resonant cavity 2 are mechanically connected by a high-frequency reed 8 to achieve electrical continuity. The mid-plane 3 is a symmetrical plane of the upper resonant cavity 1 and the lower resonant cavity 2. The high-frequency resonant cavity consists of two independent spiral structures, which are installed in a set of opposite valley regions of the main magnet.

[0018] More specifically, the cooling channel 5 is arranged in a serpentine, meandering pattern; the accelerating electrode Dee plate 6 is a spiral-shaped oxygen-free copper component, and the end of the accelerating electrode Dee plate 6 near the center area is bolted to the center area electrode 7 to ensure mechanical stability; the high-frequency spring 8 is made of oxygen-free copper and has a silver-plated surface treatment; the single inner rod 10 has an oval hole shape and a hollow structure with a wall thickness of 10mm; the cooling pipe 13 is set up with dual independent channels; the metal capacitor plate in the capacitor tuning port 14 is adjustable, with an adjustment range of 0~100mm and can achieve resonant frequency ±0.5MHz fine adjustment, and the adjustable metal capacitor plate is driven by a stepper motor; the inductive coupling ring 15 is adjustable and has a matching impedance of 50Ω, and the coaxial feed line 16 is connected to an external RF power source.

[0019] Working principle, taking the above resonant cavity 1 as an example, the resonant cavity mainly includes: a spiral cavity shell, an accelerating electrode Dee plate 6, a central region electrode 7, a single inner rod 10, a microchannel 11, a cooling water inlet and outlet 12, and a cooling pipe 13; The upper resonant cavity 1 conforms to the geometry of the valley region of the main magnet and is a three-step spiral shape. The thickness of the upper resonant cavity 1 is 18mm. The inner cavity shape is basically consistent with the outer shell shape. The shell has an independent outer wall water cooling structure, namely oxygen-free copper brazed pipe 4 and cooling channel 5, which have sufficient contact surface with the heat generation area and good cooling effect. The accelerating electrode Dee plate 6 is spiral-shaped and is connected to the central electrode 7 near the center area by bolts, which facilitates the disassembly and replacement of the central electrode 7. A high-frequency spring 8 is welded to the tail of the accelerating electrode Dee plate 6, which mechanically overlaps with the accelerating electrode Dee plate 6 on the other side at the mid-plane 3 to achieve electrical connection.

[0020] The single inner rod 10 is a hollow structure with a wall thickness of 10mm. Both ends are flange faces. The upper flange face is connected to the top of the outer shell of the cavity by bolts, and the lower flange face 9 is connected to the acceleration electrode Dee plate 6. It has high-frequency transition and water channel sealing treatment. The thin wall of the single inner rod 10 has microchannels 11, and the cooling water inlet and outlet 12 are located on the upper flange face of the single inner rod 10.

[0021] The accelerating electrode Dee plate 6 has two cooling pipes 13 inside. The water inlet and outlet both pass through the hollow area of ​​the single inner rod 10, and the water interface is made on the upper flange surface.

[0022] The acceleration gap between the resonant cavity shell and the accelerating electrode Dee plate 6 is not equal, which is a variable gap structure. The capacitance distribution is adjusted to match the resonant frequency, while improving the quality factor Q value.

[0023] The upper resonant cavity 1 and the lower resonant cavity 2 have a variable gap, which is more in line with the magnetic pole surface and suppresses the axial electric field component near the acceleration gap.

[0024] The upper resonant cavity 1 has a capacitor tuning port 14 at the top, and the capacitor tuning method is adopted.

[0025] A power coupling port is arranged at the bottom of the lower resonant cavity 2, symmetrical to the frequency tuning port of the upper resonant cavity 1, using an inductive coupling ring 15.

[0026] The inner surface of the resonant cavity is rounded to avoid arcing caused by defects such as burrs.

[0027] For components requiring electrical connection, metal springs or braided meshes are designed for overlapping.

[0028] The oxygen-free copper brazed pipe 4 and cooling channel 5 are the core components of the cooling system, directly acting on the upper resonant cavity 1 and the lower resonant cavity 2, ensuring that the cooling water can fully contact the outer shell and internal areas of the resonant cavity where high losses may occur. The oxygen-free copper brazed pipe 4 is fixed to the outside of the cavity, and the precise welding technology improves the heat conduction efficiency, avoids the generation of hot spots due to heat concentration, and the flow of coolant can continuously and effectively remove heat. The cooling channel 5 has a serpentine design, which increases the contact area and flow path of the cooling water, allowing the coolant to contact a larger surface area for a long time, avoiding local overheating and ensuring the cooling effect.

[0029] Cooling pipes 13 are positioned above and below the accelerating electrode Dee plate 6, effectively absorbing the heat generated during proton acceleration. Microchannels 11 are opened inside the single inner rod 10, and cooling water inlets and outlets are located above the single inner rod 10. This means that water can flow through the thin-walled area of ​​the inner rod, using the inner rod as a heat conduction path to enhance heat transfer and dissipation. The design of dual independent cooling pipes 13 further ensures the redundancy and stability of the cooling system. Cooling pipes 13 have two cooling paths. Under normal operation, both need to be used simultaneously. However, if one cooling path fails, the other path can still continue to work for short-term use. But repairs should be carried out as soon as possible to ensure that both cooling pipes 13 can be used simultaneously to avoid cooling system failure.

[0030] Because both the inner and outer walls of the upper resonant cavity 1 and the lower resonant cavity 2 are designed for cooling water flow, this structure avoids the accumulation of heat in local areas and achieves uniform heat distribution and dissipation. The efficiency of the cooling system in heat dissipation is supported by the oxygen-free copper brazed pipes 4 and the cooling channels 5. Copper has excellent thermal conductivity, which can quickly conduct heat and disperse it into the cooling water flow, ensuring that the various components of the accelerator will not be damaged due to overheating.

[0031] The water system is distributed and can cover the entire heating area of ​​the cavity. In particular, through the hollow structure of the microchannel 11 and the single inner rod 10, the cooling water can flow evenly through the entire cooling area, avoiding heat concentration in a certain part. The cooling system of the accelerating electrode Dee plate 6 is finely designed. Not only does cooling water flow through the inside and outside of the accelerating electrode Dee plate 6, but a high-frequency spring 8 is also welded to the tail end of the accelerating electrode Dee plate 6 to ensure that the current does not cause excessive local temperature rise, thereby affecting the normal operation of the equipment.

[0032] The single inner rod 10 adopts an oval hole design and a hollow structure with a wall thickness of 10mm. This structural design not only ensures mechanical stability inside the accelerator, but also makes it compact, easy to integrate and install, and avoids the extra space occupation caused by overly complex structures. This hollow structure design is relatively simple and reduces the processing requirements for complex shapes during the manufacturing process. Compared with other structures that may require more machining, it reduces processing steps and lowers the manufacturing difficulty.

[0033] In the design of the single inner rod 10, the microchannel 11 is located inside the thin wall of the single inner rod 10, and a cooling water inlet and outlet 12 are provided. Through this structure, the setting of the coolant flow path plays a cooling role. Due to the hollow structure of the single inner rod 10 itself, the single inner rod 10 is connected to the lower flange 9 of the accelerating electrode Dee plate 6 by bolts to maintain a stable voltage distribution, thereby realizing the adjustment of the voltage distribution. Through this simple structure and adjustment method, the adjustment of the voltage distribution becomes more direct and easier, without the need for overly complex circuit adjustment or design.

[0034] The design of the single inner rod 10 adopts a hollow oval hole structure, rather than a complex multi-layered or multi-support structure. During manufacturing, only a cylinder with a wall thickness of 10mm and flange faces at both ends need to be machined. Compared with other complex shapes, the manufacturing process is much simpler. Since the structure of the single inner rod 10 itself has multiple functions such as cooling, water channels, and mechanical support, no additional components need to be designed, avoiding the increase of parts and the complexity of the later assembly process. During the machining process, the simplicity of the hollow structure and flange face design allows the machining process to be reduced to basic turning, drilling and other conventional processes, without the need for high-precision complex milling or welding processes. This greatly reduces the time and cost in the production process.

[0035] The hollow structure not only provides sufficient strength to support the entire system's operational requirements but also effectively reduces material usage, further lowering manufacturing costs. Meanwhile, the use of oxygen-free copper ensures excellent electrical and thermal conductivity, resulting in a design that is both structurally simple and high-performing. The single inner rod 10 achieves a balance between good performance and low manufacturing costs through its simple structure and superior functionality. This design eliminates the need for complex external voltage regulation equipment; instead, it utilizes a simple built-in structure to achieve voltage regulation and cooling functions, thus avoiding expensive design and high-cost manufacturing materials.

[0036] The single inner rod 10, with its simple hollow structure and reasonable design, not only makes voltage distribution adjustment more convenient, but also significantly reduces processing complexity and manufacturing costs by reducing the number of parts and processing steps, thus possessing the advantage of high cost performance.

[0037] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A helical resonator cavity for a superconducting cyclotron, comprising: The resonant cavity is composed of an upper resonant cavity and a lower resonant cavity, and the upper resonant cavity is located directly above the lower resonant cavity, characterized in that it further comprises: The oxygen-free copper brazing pipeline is fixed in the groove on the outer wall of the upper resonant cavity and the lower resonant cavity; the cooling channel is arranged on the outer wall of the upper resonant cavity and the lower resonant cavity; the accelerating electrode Dee plate is located between the upper resonant cavity and the lower resonant cavity and is used for accelerating protons under the action of a high-frequency electric field; the central zone electrode is fixed in the accelerating electrode Dee plate; the high-frequency reed is welded at the tail end of the accelerating electrode Dee plate and is elastically pressed at the median plane of the upper resonant cavity and the lower resonant cavity with the opposite accelerating electrode Dee plate, so as to realize the electrical continuity of the two accelerating electrode Dee plates and ensure the stable transmission of the high-frequency signal; the lower flange surface is fixed on the accelerating electrode Dee plate; the single inner rod is fixed above the lower flange surface and is located in the upper resonant cavity and the lower resonant cavity; the microchannel is arranged in the thin wall of the single inner rod; the cooling water inlet and outlet are fixed above the single inner rod; the cooling pipe is fixed above and below the accelerating electrode Dee plate and is located in the single inner rod, so as to directly absorb the heat generated by the accelerating electrode Dee plate in the proton acceleration process; the capacitance tuning port is fixed on the upper resonant cavity and is used for realizing the accurate fine tuning of the resonant frequency by adjusting the internal metal capacitor plate; the inductive coupling ring is fixed on the lower resonant cavity and is used for realizing the impedance matching and power coupling of the resonant cavity and the external radio frequency system; the coaxial feeder is fixed on the inductive coupling ring and is located below the inductive coupling ring. The upper resonant cavity and the lower resonant cavity are three-step spiral structures, the thickness of the upper resonant cavity and the lower resonant cavity is 18 mm, and the inner cavities of the upper resonant cavity and the lower resonant cavity form uniform electromagnetic field distribution channels; the cooling channel is arranged in a serpentine shape; the cooling pipe is arranged in a double-path independent manner.

2. The helical resonator cavity for a superconducting cyclotron according to claim 1, wherein The upper resonant cavity and the lower resonant cavity are mirror-symmetric structures.

3. The helical resonator cavity for a superconducting cyclotron of claim 1, wherein, The accelerating electrode Dee plate is a spiral oxygen-free copper component.

4. The helical resonator cavity of claim 1, wherein, The high-frequency reed is made of oxygen-free copper and is treated by silver plating on the surface.

5. The helical resonator cavity of claim 1, wherein, The single inner rod is in the shape of a waist-round hole and has a hollow structure with a wall thickness of 10 mm.

6. The helical resonator cavity of claim 1, wherein, The metal capacitor plate in the capacitance tuning port is adjustable, and the adjustment range is 0-100 mm and the resonant frequency is fine tuned by ±0.5 MHz.

7. The helical resonator cavity of claim 1, wherein, The inductive coupling ring is adjustable, and the matching impedance is 50Ω.

8. The helical resonator cavity for superconducting cyclotrons according to claim 1, characterized in that, The coaxial feeder is connected with an external radio frequency power source.

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