Radio frequency quadrupole field accelerator and preparation process and application thereof

Abstract

The invention relates to the technical field of particle accelerators, in particular to a radio frequency quadrupole field accelerator and a preparation process and application thereof. The radio frequency quadrupole field accelerator comprises a shell and four electrode plate assemblies, each electrode plate assembly comprises a mounting part and blades, a cooling channel is arranged between each electrode plate assembly and the shell, and the four blades face each other at the axis center of the shell to form an acceleration area; the blade is formed at a time by adopting an oxygen-free copper foil with the thickness of 0.1 mm-100 mm through a plastic forming process. The core performance indexes such as the resonant frequency precision and the quality factor of the radio frequency quadrupole field accelerator can be accurately regulated and controlled according to design requirements, and in actual verification, the resonant frequency precision reaches + / -0.01%, the quality factor Q value is larger than or equal to 8000, the beam transmission efficiency is larger than or equal to 98%, the working frequency is 162.5 MHz, and the output energy is 2.5 MeV. According to the preparation process, a complex integral mechanical cutting process is avoided, and the material and processing cost is effectively reduced.

Description

Technical Field

[0001] This invention relates to the field of particle accelerator technology, and in particular to a radio frequency quadrupole accelerator, its fabrication process, and its applications. Background Technology

[0002] Radio frequency quadrupole (RFQ) accelerators are important members of the particle accelerator family, playing a crucial role in modern medical, scientific, and industrial applications. Particularly in the field of boron neutron capture therapy (BNCT), RFQ accelerators need to accelerate proton beams from low energies (approximately 35 keV) to 2.5-2.8 MeV, achieving an output current of 20 mA to meet the requirements of BNCT neutron sources.

[0003] The manufacturing of traditional RFQ accelerators faces numerous technical challenges. Firstly, material costs are high. Traditional RFQ cavities are generally made of high-purity oxygen-free copper, requiring a wall thickness of over 50mm to prevent thermal deformation. A 1-meter-long cavity consumes 3 tons of oxygen-free copper, accounting for over 50% of the material cost. Currently, the high-specification oxygen-free copper required for domestic accelerator manufacturing is primarily imported. Domestic oxygen-free copper is still in the trial stage, and its performance and stability, among other key indicators, have not yet met the requirements, thus failing to fully satisfy the manufacturing needs of accelerators. Secondly, the manufacturing process is complex. Traditional RFQs employ a monolithic machining process, requiring precision machining on a five-axis CNC machine tool. The machining accuracy requirements are extremely high, and the processing cycle can last for several weeks. Specifically, the entire material needs to be machined into four parts and then assembled into a cavity, such as... Figure 2 As shown. Experience from Lawrence Berkeley National Laboratory (LBL) in the United States shows that CNC machine tool machining accuracy can reach 0.5 mils (approximately 0.013 mm), and the average machining error of the blade tip before copper plating is 0.2-0.5 mils. Secondly, production efficiency is low. Traditional manufacturing methods rely on high-precision CNC machine tools, resulting in large equipment investments, low production efficiency, and difficulty in achieving mass production. More importantly, RFQ accelerators have previously been primarily used in scientific research. Even with recent expansion into proton and heavy ion radiotherapy, they have remained in the small-batch trial production stage, requiring continuous iteration and optimization of technical solutions. Based on this application status, the industry has generally not focused on low-cost, large-scale production technologies, nor has it conducted related process research and development—because in small-batch, non-standardized research and development production scenarios, the use of mass production processes requiring advance mold preparation is not economical, and frequent design iterations can lead to repeated mold modifications or even scrapping.

[0004] While some studies have explored composite material alternatives in existing technologies, such as the SANAEM project using 7075-T6 aluminum alloy as the RFQ cavity substrate followed by a copper coating, the bonding strength and long-term stability between the copper layer and the substrate still need verification. The integral molded RFQ developed by Lawrence Berkeley National Laboratory uses a 6061-T6 aluminum alloy substrate, undergoing zincate treatment and copper cyanide undercoating, followed by bright acid copper plating. The inner surface copper layer thickness is 1-3 mils (approximately 25-76 micrometers), and the blade tip copper layer thickness is 0.3 mils (approximately 7.6 micrometers). However, these solutions may suffer from high technical complexity, limited cost reduction, or difficulty in guaranteeing performance. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a radio frequency quadrupole accelerator and its fabrication process and application, so as to at least solve the problems of high material and processing costs and difficulty in guaranteeing accelerator performance in the prior art.

[0006] The following is a summary of this disclosure to provide a basic understanding of some aspects. This summary is not intended to identify key or important elements, nor is it intended to limit the implementation or any aspects of the claims. Furthermore, this summary provides a simplified overview of some aspects that can be described in more detail in other parts of this disclosure.

[0007] The present invention solves the above-mentioned technical problems through the following technical means:

[0008] In a first aspect, embodiments of the present invention provide a radio frequency quadrupole accelerator, comprising a housing and four electrode assemblies located inside the housing, the four electrode assemblies being symmetrically arranged around the axial center of the housing; each electrode assembly includes a mounting portion and blades, one end of the mounting portion being fixedly mounted on the inner wall of the housing, a cooling channel being provided between the electrode assembly and the housing, and the four blades forming an acceleration zone facing each other at the axial center of the housing; the blades are formed in one piece using oxygen-free copper foil with a thickness of 0.1 mm to 100 mm through a plastic forming process.

[0009] Preferably, the shape of the blade is formed using an optimization design based on seven potential functions, as follows:

[0010] U7(r,ψ,z) = (V / 2){cos2ψ(a 01 (r / a)² + a 11 I2(kr)cos(kz) + a 21 I2(2kr)cos(2kz)) + Σᵢ₌1,3,5,7 aᵢ0I5(ikr)cos(ikz)}, where a 01=0.6~1.0, a 11 =0.1~0.3, a 21 =0.1~0.2, a 10 =0.8~1.2, a 30 =0.2~0.4, a 50 =0.05~0.15, a 70 =0.03~0.07.

[0011] Preferably, the blade is formed in one step using oxygen-free copper foil with a thickness of 3mm to 8mm through a plastic forming process, wherein the plastic forming process is at least one of CNC bending, precision stamping, spinning, or rolling.

[0012] Preferably, the cavity surface of the formed blade needs to be degreased, cleaned, acid-washed and activated, and then polished or electroplated for strengthening. The surface roughness Ra of the cavity surface of the treated blade is ≤0.1μm.

[0013] Preferably, the mounting part is fixedly mounted on the inner wall of the housing by welding, riveting, or mechanical clamping.

[0014] Preferably, a sealing gasket is provided at the connection between the mounting part and the housing, and the compression amount of the sealing gasket is 15% to 25% of the thickness of the sealing gasket.

[0015] Preferably, the cooling channel is used for the flow of cooling medium to achieve cooling inside the shell, and the cooling medium is deionized water or a 50wt% ethylene glycol aqueous solution.

[0016] Preferably, the shell is made of any one of stainless steel, aluminum alloy, titanium alloy, or oxygen-free copper.

[0017] Secondly, embodiments of the present invention provide a fabrication process for a radio frequency quadrupole accelerator. The radio frequency quadrupole accelerator includes a housing and four electrode assemblies located inside the housing. The four electrode assemblies are symmetrically arranged around the axial center of the housing. Each electrode assembly includes a mounting portion and blades. One end of the mounting portion is fixedly mounted on the inner wall of the housing. A cooling channel is provided between the electrode assembly and the housing. The fabrication process includes the following steps:

[0018] S1: Copper foil pretreatment, oxygen-free copper foil with a thickness of 0.1mm to 100mm is sequentially degreased, cleaned, acid-washed and activated, and surface polished;

[0019] S2: Electrode assembly forming: The pre-treated copper foil is formed in one step using a plastic forming process to form an integral mounting part and blade;

[0020] S3: Surface treatment of the tube cavity surface. The tube cavity surface of the formed blade is degreased, cleaned, acid-washed and activated, and then polished or electroplated to strengthen it. The surface roughness Ra of the tube cavity surface after treatment is ≤0.1μm.

[0021] S4: Shell manufacturing, using any one of stainless steel, aluminum alloy, titanium alloy, or oxygen-free copper as raw materials, and forming the shell through CNC machining;

[0022] S5: Component assembly, fixing the processed electrode blade assembly to the inner wall of the housing, ensuring that the four electrode blade assemblies are symmetrically distributed;

[0023] S6: Cooling pipe assembly installation: Install the cooling pipe assembly in the cooling channel between the blades and the inner wall of the housing.

[0024] Thirdly, embodiments of the present invention provide the application of the radio frequency quadrupole accelerator described in the first and second aspects in boron neutron capture therapy.

[0025] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0026] (1) Reduced manufacturing costs: This invention uses oxygen-free copper foil of 0.1mm to 100mm to replace traditional copper materials with a wall thickness of more than 50mm, and the blades are formed in one piece by plastic forming process using oxygen-free copper foil, avoiding complex overall mechanical cutting process, and effectively reducing material and processing costs.

[0027] (2) Production efficiency is significantly improved. Based on the design and finalization of BNCT in the market application scenario, the manufacturing cycle is shortened from the traditional 3-4 weeks to 5-7 days (this cycle is the batch production cycle after design finalization, excluding the mold preparation time), which is 85% shorter. No expensive five-axis linkage CNC machine tool is required, only conventional bending machine or stamping equipment is needed to achieve modular batch production.

[0028] (3) Excellent performance indicators. The core performance indicators such as resonant frequency accuracy and quality factor can be precisely controlled according to design requirements. In actual verification, the resonant frequency accuracy reached ±0.01%, the quality factor Q value ≥8000, which is comparable to the traditional pure copper RFQ, the beam transmission efficiency ≥98%, the working frequency 162.5MHz (can be adjusted according to requirements), the output energy 2.5MeV (protons), and the output current intensity 20mA.

[0029] (4) The structure has obvious advantages. Through optimized design, the overall size is more compact and the volume is effectively reduced.

[0030] (5) High sealing reliability: A special sealing gasket is added at the fixed connection between the blade and the inner wall of the shell. Combined with the double sealing design of copper gasket metal seal, it can effectively avoid leakage of cooling medium and decrease in vacuum degree. The vacuum seal life is ≥5 years, reducing the frequency and cost of equipment maintenance. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the cross-section of the radio frequency quadrupole accelerator of the present invention;

[0032] Figure 2 This is a schematic diagram of a traditional RFQ accelerator.

[0033] The components include a housing 100, a mounting section 210, blades 220, an acceleration zone 300, and a cooling channel 400. Detailed Implementation

[0034] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0035] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0036] As an explanation, a traditional radio frequency quadrupole accelerator (RFQ accelerator) is designed with a high vacuum inside the accelerator housing and four accelerating electrodes inside the housing. A standing wave electromagnetic field with a specific resonant frequency is formed in the RFQ accelerator cavity using a high-frequency power coupler. Without considering the periodic modulation changes in the shape of the four electrode tips, the four electrodes of the RFQ accelerator can be regarded as electric quadrupole lenses whose electric field intensity oscillates sinusoidally with time. They have a focusing or defocusing effect on charged particles entering between the four accelerating electrodes. The focusing or defocusing depends on the velocity of the charged particles along the central axis of the RFQ accelerator and the vibration phase of the standing wave electromagnetic field when they reach a given z-direction position. Therefore, during the entire motion process, the charged particles can be focused and defocused by the electric quadrupole lenses, just like charged particles passing through a transport line composed of quadrupole electromagnets. Meanwhile, since the geometry of the electrode heads of the four electrodes has a wave-like periodic modulation change along the z-direction, the period length of the wave increases with the increase of the charged particle velocity. At the same time, since the electrode wave modulation positions of the opposing electrodes are completely consistent along the Z-direction, the wave positions between adjacent electrodes differ by half a wave period. Therefore, in addition to the above-mentioned focusing and defocusing effects on charged particles, there is also an Ez electric field component that accelerates charged particles. This can achieve velocity modulation, longitudinal focusing, and acceleration of charged particles. This is the principle of the RFQ accelerator for accelerating charged particles.

[0037] like Figure 1 As shown, the radio frequency quadrupole accelerator of this application includes a housing 100 and four electrode assemblies located inside the housing 100. The four electrode assemblies are arranged symmetrically around the axis of the housing. Each electrode assembly includes a mounting part 210 and blades 220. One end of the mounting part 210 is fixedly mounted on the inner wall of the housing 100. A cooling channel 400 is provided between the electrode assembly and the housing 100. At the axis of the housing 100, the four blades 220 face each other to form an acceleration zone 300. The blades 220 are formed in one piece using oxygen-free copper foil with a thickness of 0.1 mm to 100 mm through a plastic forming process.

[0038] The housing 100 is constructed from a sealed vacuum chamber using a metal material whose performance meets design requirements. The shape of the housing 100 includes, but is not limited to, circles and regular polygons. The materials used to manufacture the housing include, but are not limited to, stainless steel, aluminum alloy, titanium alloy, or oxygen-free copper, with 316L stainless steel being the preferred choice. End plates are provided at both ends of the housing 100 along its axial direction. The thickness of the housing 100 and the end plates are designed according to usage requirements. The housing 100 and the end plates are fixed by welding or bolting. The blade 220 is formed in one piece using oxygen-free copper foil with a thickness of 0.1mm to 100mm through a plastic forming process. Preferably, the blade 220 is formed using oxygen-free copper foil with a thickness of 3mm to 8mm, and the copper foil purity is ≥99.95%. Theoretically, a copper foil thickness greater than four times the skin depth at the corresponding operating frequency can meet the requirements for RF current transmission. A thickness range of 0.1mm to 100mm can fully cover the wide range of application requirements for different power and frequency RFQs, while also taking into account the mechanical strength, temperature deformation control, and long-term stability requirements in various scenarios. Plastic forming processes include CNC bending, precision stamping, spinning, and rolling. During the forming process, reinforcing structures such as ribs and tubes can be added according to mechanical performance requirements to enhance the bending and deformation resistance of the blade 220.

[0039] The shape of blade 220 is formed by an optimization design based on 7 potential functions, as follows:

[0040] U7(r,ψ,z) = (V / 2){cos2ψ(a 01 (r / a)² + a 11 I2(kr)cos(kz) + a 21 I2(2kr)cos(2kz)) + Σᵢ₌1,3,5,7 aᵢ0I5(ikr)cos(ikz)}, where a 01 =0.6~1.0, a 11 =0.1~0.3, a 21 =0.1~0.2, a 10 =0.8~1.2, a 30 =0.2~0.4, a 50 =0.05~0.15, a 70 =0.03~0.07. When using the above-mentioned optimized design of the blade 220 shape based on 7 potential functions, the coefficients can be optimized through finite element simulation tools, which can improve the acceleration efficiency by more than 15%.

[0041] After the blade 220 is formed, the cavity surface needs to be degreased, cleaned, acid-washed and activated, and then polished or electroplated to strengthen it. The surface roughness Ra of the cavity surface of the blade 220 after treatment is ≤0.1μm (the specific accuracy is adjusted according to the design requirements) to improve the conductivity and surface smoothness.

[0042] The mounting part 210 is fixed to the inner wall of the housing 100 by laser welding, micro-beam plasma arc welding, copper rivet riveting or elastic clamp mechanical clamping. The spacing between the fixing points is determined according to the design requirements.

[0043] A sealing gasket is provided at the connection between the mounting section 210 and the housing 100. The sealing gasket is made of fluororubber or metal-coated gasket to ensure the isolation and sealing between the cooling channel 400 and the vacuum chamber, and to prevent the leakage of cooling medium from affecting the vacuum environment. The compression amount of the sealing gasket is determined according to the characteristics of the sealing material, and preferably the compression amount is 15% to 25% of the thickness of the sealing gasket.

[0044] The cooling pipe assembly is used to circulate the cooling medium to achieve cooling inside the shell 100. The cooling pipe assembly includes a cooling channel 400 located between the blade 220 and the inner wall of the shell 100. The cross-sectional shape of the cooling channel 400 can be rectangular or circular. The channel size, cooling medium type and flow rate are determined according to design requirements. Preferably, the channel width is 10mm to 100mm, the height is 5mm to 50mm, the cooling medium is deionized water (resistivity ≥10MΩ·cm) or 50wt% ethylene glycol aqueous solution, the flow rate is 5L / min to 20L / min, the pressure loss is <0.5MPa, and the inlet and outlet temperature difference is <5℃.

[0045] In specific implementation, for example, the cooling channel 400 is set as a rectangular cross section with a channel size of 10mm×3mm. Deionized water with a resistivity of 15MΩ·cm is used as the cooling medium, and the flow rate of the cooling medium is controlled at 10 L / min. Four temperature sensors are evenly arranged. After running continuously for 2 hours at an input power of 20kW, the test results show that: the highest temperature of the cavity is 28℃, which meets the temperature control design requirements; the temperature uniformity is ±1.5℃; and the inlet and outlet temperature difference is 3.2℃.

[0046] In some embodiments, the radio frequency quadrupole accelerator of this application further includes a radial support structure and an axial support structure. The radial support uses stainless steel or titanium alloy support rods (to meet vacuum compatibility requirements). The diameter of the support rod and the spacing between support points are adjusted according to the thickness and weight of the blade 220, preferably with a diameter of 10mm to 20mm and a spacing between support points of 150mm to 300mm (for 3mm to 8mm blades 220, a diameter of 10mm to 12mm and a spacing between support points of 200mm to 250mm are used). The radial support rod is set as an adjustable structure, and the support force is adjusted by a threaded adjustment device. The preload is determined according to the thickness and weight of the blade 220, preferably with a preload of 80 to 300N (for 3mm to 8mm blades 220, the preload is 80 to 150N). Under the action of vacuum pressure difference, the maximum deformation of the cavity and the positional offset of the blade 220 are controlled according to design requirements, preferably with the maximum deformation of the cavity not exceeding 0.1mm and the positional offset of the blade 220 not exceeding 0.02mm. The axial support adopts an external support frame, which is fixed to the foundation by support legs. The support structure design needs to be verified by finite element mechanical simulation to ensure the structural stability in a vacuum environment.

[0047] In specific implementation, for example, the radial support uses a 316L stainless steel rod with a diameter of 1212mm and a support point spacing of 2250mm (to meet the weight support requirements of the 3-8mm preferred range blade 220). The radial support rod is equipped with a threaded adjustment device and a preload of 120N. The axial support adopts a rectangular structure with a support leg spacing of 1000mm. Performance testing, under a vacuum pressure difference of 100kPa (approximately 1 atmosphere), through finite element analysis and actual testing, showed that the maximum deformation of the cavity was 0.08mm (less than the design requirement of 0.1mm), the blade 220 position offset was 0.015mm (less than the design requirement of 0.02mm), and the structural natural frequency was ≥50Hz (avoiding resonance and meeting design requirements).

[0048] In some embodiments, the radio frequency quadrupole accelerator of this application can be designed in axial segments according to design requirements. The axial length of each segment is preferably 0.5 to 1.5 m. Each segment is fixedly connected by a standard flange interface. The connection accuracy is determined according to design requirements, and preferably ±0.02 mm.

[0049] On the other hand, the fabrication process of the radio frequency quadrupole accelerator of this application includes the following steps:

[0050] S1: Copper foil pretreatment, oxygen-free copper foil with a thickness of 0.1mm to 100mm is sequentially degreased, cleaned, acid-washed and activated, and surface polished.

[0051] S2: Electrode assembly forming. Oxygen-free copper foil is formed in one step using plastic forming processes such as CNC bending, precision stamping, or roll forming. During forming, reinforcing structures such as ridges and tubes are added according to mechanical performance requirements. Forming accuracy is determined according to design requirements, with an optimal forming accuracy of ±0.05mm and a surface roughness Ra≤0.1μm. The bending process uses a CNC bending machine. The bending angle accuracy and bending radius are adjusted according to the copper foil thickness, with an optimal bending angle accuracy of ±0.1° and a bending radius of 3mm~15mm. The stamping process uses precision stamping dies. The stamping speed and stamping force are determined according to the copper foil thickness, with an optimal stamping speed of 1mm / s~8mm / s and a stamping force of 50 tons~1000 tons (suitable for forming requirements across the entire thickness range of 0.1mm~100mm). The formed blade 220 needs to be dimensionally inspected using a coordinate measuring machine, with a core dimension inspection accuracy of ±0.01mm.

[0052] S3: Surface treatment of the tube cavity surface. The tube cavity surface of the formed blade 220 is subjected to degreasing cleaning, acid pickling activation, surface polishing or electroplating strengthening, etc. The surface roughness Ra of the tube cavity surface of the treated blade 220 is ≤0.1μm.

[0053] S4: Shell 100 is manufactured using any one of stainless steel, aluminum alloy, titanium alloy, or oxygen-free copper as raw material, and formed by CNC machining.

[0054] S5: Component assembly. The processed electrode blade components are fixedly installed on the inner wall of the housing 100 by welding, riveting or mechanical clamping, etc., to ensure that the four electrode blade components are symmetrically distributed.

[0055] S6: Cooling pipe assembly installation. Install the cooling pipe assembly in the cooling channel 400 between the blade 220 and the inner wall of the housing 100. After installation, perform a pressure test. The test pressure and holding time are determined according to design requirements. The preferred test pressure is 0.5 to 1.0 MPa, and the holding time is not less than 30 minutes.

[0056] If mass production is required, blade 220 molds will be prepared. Based on the design shape and size of blade 220, precision stamping molds or bending molds will be manufactured using CNC machining. The mold material will be Cr12MoV alloy tool steel, which will be quenched and tempered. The working surface of the mold will be polished and nitrided to ensure that the mold hardness is ≥HRC60, the surface roughness Ra≤0.02μm, and the mold service life is ≥100,000 cycles, meeting the mold precision and durability requirements for large-scale production.

[0057] The radio frequency quadrupole accelerator and its fabrication process of this application will be described below through Examples 1-2:

[0058] Example 1

[0059] This embodiment provides a 162.5MHz RFQ accelerator for boron neutron capture therapy (BNCT). Its technical parameters are designed and determined according to the needs of BNCT treatment: operating frequency 162.5MHz, input energy 35keV (protons), output energy 2.5MeV (protons), output current 20mA, number of accelerator units 180, and cavity length 3.2m.

[0060] The housing 100 of the radio frequency quadrupole accelerator in this embodiment is made of 316L stainless steel (the material properties meet the design requirements for vacuum sealing and structural support), with a wall thickness of 8 mm and an end plate thickness of 15 mm. The blades 220 are made of 4 mm thick high-purity oxygen-free copper foil with a purity ≥99.95%. The cooling medium is deionized water with a resistivity ≥10 MΩ·cm. Copper gaskets and fluororubber gaskets are used for sealing; the copper gaskets are used for metal sealing, and the fluororubber gaskets are used at the connection between the blade mounting part 210 and the inner wall of the housing 100.

[0061] The fabrication process of the radio frequency quadrupole accelerator in this embodiment is as follows:

[0062] S0: Mold preparation. The blade 220 stamping die is made of Cr12MoV alloy tool steel. The die is quenched and tempered, and the working surface is polished and nitrided. The die hardness is HRC62 and the surface roughness is Ra=0.01μm. The die size is machined according to the shape optimized by the 220 blade 7 potential function. The die gap is 0.02mm to ensure forming accuracy.

[0063] S1: Copper foil pretreatment. The oxygen-free copper foil with a thickness of 4mm is subjected to surface treatment, including degreasing and cleaning, pickling and activation, and surface polishing. The surface roughness of the treated copper foil is Ra=0.08μm to ensure the quality of subsequent forming and welding.

[0064] S2: Blade 220 forming is achieved through a one-time bending process using a CNC bending machine. During the forming process, three reinforcing ribs (isosceles triangle cross-section, 5mm high, 8mm base width) are added along the length of blade 220 to enhance its resistance to deformation. The bending angle accuracy is ±0.1°, and the bending radius is 5mm (suitable for forming 4mm thick copper foil). The shape of blade 220 adopts an optimized design based on seven potential functions. The potential function parameters are: a 01 =0.8, a 11 =0.2, a 21 =0.15, a 10 =1.0, a 30 =0.3, a 50 =0.1, a 70 =0.05. The shape error of the formed blade 220 is ≤±0.05mm, and the surface is free of defects such as cracks and wrinkles.

[0065] S3: Surface treatment of the tube surface: According to the design requirements, the tube surface of the formed blade 220 is electrochemically polished, and the surface roughness Ra=0.06μm after treatment, which improves the efficiency of radio frequency current transmission.

[0066] S4: The housing 100 is manufactured from 3mm thick 316L stainless steel sheet (can be made into a circle or regular polygon according to requirements), and is automatically argon arc welded. The weld is inspected by X-ray. The end plate is machined by CNC machining center, the flange surface flatness is ≤0.05mm, and the sealing surface roughness Ra≤1.6μm.

[0067] S5: Component assembly. A dedicated positioning fixture is used to ensure that the four blades 220 are symmetrically distributed, with a blade spacing error of ≤±0.05mm. A fluororubber sealing gasket (2mm thick, 0.4mm compressed) is laid on the connection surface between the blade 220 and the housing 100. The blades 220 are fixed by laser welding with a welding power of 150W, a welding speed of 8mm / s, and a weld point spacing of 100mm.

[0068] S6: Cooling system installation, forming a cooling channel 400 between the blade 220 and the inner wall of the housing 100. The channel has a rectangular cross-section, 10mm wide and 3mm high. This structure is consistent with... Figure 1 The water cooling piping between the blade 220 and the tube wall is consistent with the standard. The inlet and outlet pipes are made of φ10mm stainless steel and connected via compression fittings. After installation, the cooling system undergoes a pressure test at 0.8MPa for 30 minutes.

[0069] S7: Vacuum sealing treatment. The assembled cavity is vacuum sealed using copper gaskets, achieving a vacuum level of 1×10⁻⁻. 6 Pa, sealing leakage rate ≤1×10⁻ 9 Pa·m³ / s; Vacuum leak detection is performed using a helium mass spectrometer to ensure that the sealing performance meets the standards.

[0070] The following quality checks were also performed during the preparation process of this embodiment:

[0071] ① Raw material testing: The purity of the copper foil was verified to be 99.99% by spectral analysis, and the thickness uniformity error was ±0.5μm; the mechanical properties of 316L stainless steel were tested, with a yield strength ≥205MPa and a tensile strength ≥515MPa.

[0072] ② Process inspection: After the blade is formed, it is measured by a coordinate measuring machine, and the core size error is ±0.008mm; after welding, it is tested by ultrasonic testing and there are no defects such as incomplete penetration or porosity.

[0073] ③ Finished product inspection: Electrical performance tests such as resonant frequency and quality factor are qualified; vacuum leakage rate is 5×10⁻¹. 0 Pa·m³ / s, which meets the design requirements.

[0074] The performance test results of the radio frequency quadrupole accelerator in this embodiment are as follows: resonant frequency 162.5000±0.0016MHz (accuracy 0.001%, meeting design requirements), quality factor Q=8750 (better than design requirements), insertion loss ≤0.5dB, voltage standing wave ratio ≤1.15, power loss 45kW (at 20kW input power), temperature distribution: maximum cavity temperature 28℃, temperature uniformity ±1.5℃.

[0075] Example 2

[0076] The radio frequency quadrupole accelerator in this embodiment adopts a modular design. The standard module length is determined to be 1.0m for mass production adaptability, and it can be combined into RFQ accelerators of different lengths as needed. The module types include acceleration modules, transition modules, and terminal modules. Each module is fixedly connected by a standardized flange interface with a connection accuracy of ±0.02mm.

[0077] The processing materials for the radio frequency quadrupole accelerator in this embodiment are the same as those in Embodiment 1. The mass production process for the radio frequency quadrupole accelerator in this embodiment is as follows:

[0078] (1) Module prefabrication

[0079] ① Blade manufacturing: mass production is carried out using stamping dies. Four blades can be produced in a single stamping. The precision of the die is determined according to the blade forming design requirements. During the forming process, the tube structure is reinforced by integral forming with the die to improve mechanical properties.

[0080] ② Shell manufacturing uses automated production lines, including laser cutting, bending, welding and other processes. The processing accuracy is controlled according to the frame support and sealing design requirements.

[0081] ③ Cooling system: The cooling pipes use standardized components that can be quickly assembled. The precision of the components is determined according to the design requirements of the cooling flow rate.

[0082] (2) Quality control

[0083] ① Dimensional inspection: A coordinate measuring machine is used, and the inspection accuracy is determined according to the design requirements of each component. The core dimension inspection accuracy is ±0.01mm. At the same time, surface roughness inspection is carried out to ensure that the blade cavity surface Ra≤0.1μm.

[0084] ② Electrical testing, testing resonant frequency and quality factor, with a pass rate of ≥99%.

[0085] ③ Vacuum testing: Each module undergoes a vacuum test individually, using a helium mass spectrometer leak detector to check the leakage rate, ensuring a vacuum level ≤1×10⁻ 6 Pa, sealing leakage rate ≤1×10⁻ 9 Pa·m³ / s (meets vacuum transport design requirements).

[0086] (3) On-site assembly

[0087] The modular design facilitates transportation, with each module weighing ≤50kg. Standardized flange interfaces enable secure connections between modules, reducing connection time between modules to ≤30 minutes and overall system debugging time to ≤8 hours. This embodiment reduces the production cycle of the RF quadrupole accelerator from design to delivery to 2 weeks.

[0088] The foregoing description includes examples from this specification. Of course, for the purposes of describing this specification, it is impossible to describe every conceivable combination of components or methods; however, those skilled in the art will understand that many other combinations and arrangements are possible. Therefore, this specification is intended to cover all such changes, modifications, and variations that fall within the spirit and scope of the appended claims. Furthermore, with regard to the use of the term "comprising" in the detailed description or claims, the term is intended to be inclusive in a manner similar to the term "including," as interpreted when "comprising" is used as a transitional word in the claims.

[0089] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A radio frequency quadrupole accelerator characterized by, The application relates to a radio frequency quadrupole field accelerator, which comprises a shell and four electrode sheet assemblies arranged symmetrically around the axial center of the shell; the electrode sheet assembly comprises a mounting part and a blade, one end of the mounting part is fixedly mounted on the inner wall of the shell, a cooling channel is arranged between the electrode sheet assembly and the shell, and four blades are oppositely arranged at the axial center of the shell to form an acceleration area; the blade is integrally formed by plastic forming process of oxygen-free copper foil with a thickness of 0.1mm-100mm.

2. A radio frequency quadrupole accelerator according to claim 1 wherein, The shape of the blade is formed by an optimized design based on seven potential functions, and the optimized design based on the seven potential functions is as follows: U7(r,ψ,z) = (V / 2){cos2ψ(a 01 (r / a)² + a 11 I2(kr)cos(kz) + a 21 I2(2kr)cos(2kz)) +Σᵢ₌1,3,5,7 aᵢ0I5(ikr)cos(ikz)}, among them a 01 =0.6~1.0,a 11 =0.1~0.3,a 21 =0.1~0.2,a 10 =0.8~1.2,a 30 =0.2~0.4,a 50 =0.05~0.15,a 70 =0.03~0.

07.

3. A radio frequency quadrupole accelerator according to claim 1 wherein, The blade is integrally formed by plastic forming process of oxygen-free copper foil with a thickness of 3mm-8mm, and the plastic forming process is at least one of numerical control bending, precision stamping, spinning or rolling.

4. A radio frequency quadrupole accelerator according to claim 3 wherein, The lumen surface of the formed blade needs to be subjected to degreasing cleaning, pickling activation, surface polishing or electroplating strengthening treatment, and the surface roughness Ra of the lumen surface of the treated blade is less than or equal to 0.1mu m.

5. A radio frequency quadrupole accelerator according to claim 1 wherein, The mounting part is fixedly mounted on the inner wall of the shell by welding, riveting or mechanical clamping.

6. A radio frequency quadrupole accelerator according to claim 5 wherein, A sealing gasket is arranged at the connecting position of the mounting part and the shell, and the compression amount of the sealing gasket is 15%-25% of the thickness of the sealing gasket.

7. A radio frequency quadrupole accelerator according to claim 1 wherein, The cooling channel is used for flowing of cooling medium to realize temperature reduction in the shell, and the cooling medium is deionized water or 50wt% ethylene glycol aqueous solution.

8. A radio frequency quadrupole accelerator according to claim 1 wherein, The preparation material of the shell is any one of stainless steel, aluminum alloy, titanium alloy and oxygen-free copper.

9. A process for the preparation of a radio frequency quadrupole accelerator, characterized in that, The radio frequency quadrupole field accelerator comprises a shell and four electrode sheet assemblies arranged symmetrically around the axial center of the shell, the electrode sheet assembly comprises a mounting part and a blade, one end of the mounting part is fixedly mounted on the inner wall of the shell, and a cooling channel is arranged between the electrode sheet assembly and the shell; the preparation process comprises the following steps: S1: copper foil pretreatment, oxygen-free copper foil with a thickness of 0.1mm-100mm is subjected to degreasing cleaning, pickling activation and surface polishing treatment in sequence; S2: electrode sheet assembly forming, the pretreated copper foil is integrally formed by plastic forming process to form an integrated mounting part and blade; S3: lumen surface treatment, the lumen surface of the formed blade is subjected to degreasing cleaning, pickling activation, surface polishing or electroplating strengthening treatment, and the surface roughness Ra of the lumen surface of the treated blade is less than or equal to 0.1mu m; S4: shell manufacturing, any one of stainless steel, aluminum alloy, titanium alloy and oxygen-free copper is used as a raw material to manufacture the shell by numerical control machining; S5: assembly assembly, the treated electrode leaf assembly is fixedly mounted on the inner wall of the shell to ensure that the four electrode leaf assemblies are symmetrically distributed; S6: cooling pipeline assembly installation, a cooling pipeline assembly is installed in the cooling channel between the blade and the inner wall of the shell.

10. Application of the radio frequency quadrupole field accelerator according to claims 1-9 in boron neutron capture therapy.

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