Two-half symmetrical structure low-loss ceramic dielectric auxiliary acceleration structure and method
By using a low-loss ceramic dielectric body with a two-half symmetrical structure design, the problems of current path interruption and assembly gap in dielectric-assisted acceleration structures are solved, achieving a particle acceleration effect with low loss, high stability and high reliability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-29
- Publication Date
- 2026-04-07
AI Technical Summary
Existing dielectric-assisted acceleration structures suffer from current path detours or interruptions during processing and assembly, resulting in additional ohmic losses and impedance discontinuities. Furthermore, there is a risk of partial discharge due to assembly gaps, which affects the efficiency and reliability of the accelerator.
The low-loss ceramic dielectric body, which adopts a two-half symmetrical structure design, is composed of two half-rings to ensure the continuous flow of the dominant high-frequency current. It also reduces assembly gaps through a precision positioning structure and optimized design, and is fixed by an annular mounting groove in the metal cavity and active metal brazing process.
It significantly reduces RF power loss, reduces the risk of arcing, improves the energy utilization efficiency and operational stability of the accelerator, extends equipment life, and improves beam quality and acceleration efficiency.
Smart Images
Figure CN121815530A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of particle accelerators, in particular to a two-half-symmetry low-loss ceramic medium assisted acceleration structure and method. BACKGROUND
[0002] As the core component of particle accelerators, the core function of particle acceleration structure is to provide stable and efficient acceleration field for charged particles. In the field of accelerator technology, low loss has always been a key pursuit goal, because low loss is directly related to the running efficiency, energy stability and long-term running reliability of the accelerator.
[0003] Medium assisted acceleration structure is an important technical path that has emerged in recent years. It loads low-loss dielectric material inside the traditional metal (such as copper) acceleration cavity, uses the electromagnetic field distribution characteristics of a specific acceleration mode (such as TM020-π mode), and relies on the reflection of the dielectric layer to the microwave, which can significantly reduce the power loss of the whole cavity, and then improve the overall efficiency of the acceleration structure.
[0004] However, the commonly used medium assisted acceleration structure at present adopts segmented structure to realize the loading of dielectric material in the process of processing and assembling. Specifically, the dielectric material is made into multiple independent segments, and then assembled into the metal cavity. This segmented structure has many significant shortcomings: Firstly, it will cut off the surface current of the working mode. When the acceleration cavity is working, a specific high-frequency surface current path will be formed on its inner wall. The segmented dielectric structure will physically cut off the continuous path of the current, causing the current path to be forced to detour or interrupted, resulting in additional ohmic loss and impedance discontinuity, increasing unnecessary radio frequency loss and reducing the overall efficiency of the structure.
[0005] Secondly, it introduces the risk of structural gap and sparking. There must be assembly gaps between each dielectric segment. In the high-power and strong electric field environment of the accelerator, these gaps are prone to electric field concentration, significantly increasing the risk of partial discharge (sparking). The sparking phenomenon not only affects the stability of the acceleration field and the quality of the beam, but also may cause irreversible damage to the surface of the dielectric and metal cavity, threatening the safety and life of the equipment.
[0006] Thirdly, it brings process complexity and reliability problems. Multi-segment assembly requires high precision and assembly process. Any size deviation or assembly misalignment of a segment may exacerbate the above-mentioned loss and sparking problems, reducing the consistency and long-term running reliability of the structure.
[0007] Therefore, it is of great practical significance to develop a new type of medium assisted acceleration structure that can effectively solve the above problems. SUMMARY
[0008] In view of the above problems, the application aims to provide a two-half-symmetrical low-loss ceramic medium auxiliary accelerating structure and method, which is particularly suitable for particle accelerating scenarios with high requirements for accelerating efficiency, energy stability and long-term operation reliability, and effectively reduces the RF power loss and sparking risk of the accelerating structure and improves the overall performance of the accelerator through innovative medium structure design.
[0009] The technical solution adopted by the application is: a two-half-symmetrical low-loss ceramic medium auxiliary accelerating structure, comprising a metal cavity and a low-loss ceramic medium body arranged in the metal cavity, the low-loss ceramic medium body is composed of at least two ceramic medium components, and the extension direction of the joint gap between the ceramic medium components is substantially parallel to the flow direction of the dominant high-frequency current on the inner surface of the accelerating structure in the working mode.
[0010] The low-loss ceramic medium body is annular, and the at least two ceramic medium components are two half-ring bodies which are symmetrically divided along a plane containing the axis of the ring and are spliced.
[0011] A precise positioning structure is arranged on the abutting surface of the two half-ring bodies, the positioning structure is a boss and groove matching structure, so as to ensure accurate alignment during assembly and form seamless cylindrical inner and outer surfaces.
[0012] The joint gap is a linear joint, and the total number of all joint gaps is N, where 2≤N≤6, preferably 2.
[0013] After splicing, the low-loss ceramic medium body does not have an insulating gap that completely blocks the flow of the dominant high-frequency current at the joint surface, so that the dominant high-frequency current can continuously flow along the inner surface of the low-loss ceramic medium body.
[0014] The inner diameter, outer diameter and axial length of the low-loss ceramic medium ring are optimized according to the electromagnetic field simulation results of the supported accelerating mode, and the accelerating mode is TM020-π mode.
[0015] The low-loss ceramic medium ring is a uniform medium ring, and the material is high-purity alumina or magnesia ceramic; or the low-loss ceramic medium ring is a composite or gradient medium ring composed of two or more low-loss ceramic materials; or microchannels for liquid cooling are integrated inside the low-loss ceramic medium ring or at the interface with the metal.
[0016] The metal cavity is designed with a corresponding annular mounting groove, the low-loss ceramic medium body is embedded in the annular mounting groove as a whole, or is fixed by press fitting after segmented assembly; a thin layer of transition material is arranged between the low-loss ceramic medium body and the metal cavity, or an active metal brazing process is used.
[0017] A method for manufacturing a two-half-symmetrical low-loss ceramic dielectric auxiliary accelerating structure, comprising: processing at least two ceramic dielectric components; assembling the components into a ceramic dielectric body in a manner that the extension direction of the splicing joint between the components is substantially parallel to the main high-frequency current flow direction of the inner surface of the accelerating structure when the accelerating structure is in operation; mounting the assembled ceramic dielectric body in a metal cavity provided with a corresponding annular mounting groove in a manner of being integrally embedded in the annular mounting groove or being segmented and fixed by pressing; and setting a thin layer of transition material or using active metal brazing process between the ceramic dielectric body and the metal cavity.
[0018] The method for manufacturing a two-half-symmetrical low-loss ceramic dielectric auxiliary accelerating structure, the at least two ceramic dielectric components are two half-ring bodies, and the medium cylindrical body is symmetrically divided along a plane containing the axis of the ring during processing; the abutting surface of the two half-ring bodies is processed with a precise positioning structure, which is a boss and groove matching structure; the inner diameter, outer diameter and axial length of the low-loss ceramic dielectric ring are optimized and designed according to the electromagnetic field simulation results of the supported accelerating mode (TM020-π mode); the low-loss ceramic dielectric ring is a uniform medium ring, the material is high-purity alumina or magnesia ceramic, or a composite or gradient medium ring, or integrated with a micro-channel for liquid cooling; and the fixing mode of mounting the assembled ceramic dielectric body in the metal cavity is one of mechanical pressing, brazing or diffusion welding, and precise fitting without adhesive.
[0019] The two-half-symmetrical low-loss ceramic dielectric auxiliary accelerating structure and method have the following advantages: The low-loss ceramic dielectric is designed to be spliced by two geometrically symmetrical halves, which fundamentally ensures that the inner wall surface current of the accelerating structure can flow along a continuous and complete path in the TM020-π mode, avoiding the interruption and disturbance of the current path caused by segmented media. Since the surface current path is continuous and uninterrupted, additional ohmic loss and parasitic mode excitation caused by current detouring or mode disturbance are avoided. Tests and simulations show that the unloaded quality factor (Q0) of the structure can be improved by more than 20% compared with the traditional segmented structure under the same operating frequency and gradient, greatly improving the energy utilization efficiency.
[0020] The two half-symmetrical structures of the application greatly reduce the number and length of assembly gaps between dielectric components, thereby effectively suppressing the local electric field concentration phenomenon under high electric field environment. The structural high electric field risk point is reduced from "multiple annular gaps" in the traditional multi-section structure to "one controllable longitudinal joint". The joint can be controlled at the micron level through precision machining and assembly, and its electric field enhancement factor is much lower than that of the annular gap, thereby reducing the secondary electron multiplication and radio frequency breakdown risk under high power by an order of magnitude, enhancing the stability and safety of the accelerator operation.
[0021] The two half-symmetrical structures of the application simplify the assembly process and reduce the problems of uneven stress or misalignment caused by the cumulative tolerance of multiple parts. Fewer joints also mean fewer potential air leaks and thermal contact resistance points, improving the long-term reliability of the entire accelerating cavity under vacuum and thermal cycling, and prolonging the service life of the equipment.
[0022] The "completely symmetrical half-ring body" feature in the application ensures the symmetry of the electromagnetic field in the structure, prevents the introduction of dipole modes or off-axis fields due to asymmetric dielectric, and thus guarantees the stability of beam dynamics and improves the beam quality.
[0023] The "precision butt joint positioning structure" feature in the application directly ensures that the width and straightness of the joint are controllable, which is a key process guarantee for achieving low loss and low sparking risk. Precise positioning minimizes the radio frequency impedance mutation at the joint, further optimizing the performance of the accelerating structure.
[0024] Maintaining the integrity of the accelerating mode field pattern: The "overall dielectric ring" concept (although composed of two halves, but functionally continuous) allows the dielectric to function as a complete electromagnetic boundary, effectively maintaining the field pattern distribution of the TM020-π mode and improving the acceleration efficiency. BRIEF DESCRIPTION OF DRAWINGS
[0025] Figure 1 is a structural schematic diagram of the application; Figure 2 is an exploded structural schematic diagram of the application; Figure 3 is a ceramic dielectric body structure schematic diagram in the application; Figure 4 is a ceramic dielectric body cross-section structure schematic diagram in the application; Figure 5 is a working principle schematic diagram of the application.
[0026] 1-metal cavity, 2-ceramic dielectric body, 21-upper ceramic, 22-lower ceramic. DETAILED DESCRIPTION
[0027] The two half-symmetrical structure low-loss ceramic dielectric auxiliary accelerating structure and the manufacturing method thereof will be described in detail below in combination with the accompanying drawings of the specification. In the drawings, Figures 1-2 The structure of the present application shows the assembly relationship of the low-loss ceramic dielectric ring and the metal cavity 1. Figures 3-4 It is a schematic diagram of the ceramic dielectric body structure in the present application, Figure 5 It is a schematic diagram of the working principle, which presents the current and electric field distribution of the accelerating structure when it is working. The following will be described through specific embodiments: Embodiment 1: Two half-symmetrical structure low-loss ceramic dielectric auxiliary accelerating structure As shown in the figure, Figures 1-5 The embodiment provides a two half-symmetrical structure low-loss ceramic dielectric auxiliary accelerating structure, which comprises a metal cavity 1 and a low-loss ceramic dielectric body 2 arranged in the metal cavity 1.
[0028] In the embodiment, the low-loss ceramic dielectric body 2 is annular and is composed of two half-ring bodies, which comprise an upper ceramic 21 and a lower ceramic 22. The two half-ring bodies are symmetrically divided along a plane containing the axis of the ring, which comprises a cylindrical ceramic dielectric ring. The dividing plane is perpendicular to the axis of the accelerator to ensure that the two halves are completely consistent in geometry, size and mass.
[0029] In the embodiment, a precise positioning structure is arranged on the abutting surface of the two half-ring bodies, which adopts a boss and groove matching structure. During processing, the size and shape of the boss and groove are accurately controlled so that they can be accurately aligned during assembly to form seamless cylindrical inner and outer surfaces. This positioning structure ensures that the split ceramic dielectric ring has high dimensional accuracy and assembly quality.
[0030] In the embodiment, the inner diameter, outer diameter and axial length of the low-loss ceramic dielectric ring are optimized according to the electromagnetic field simulation results of the supported acceleration mode (TM020-π mode). Through professional electromagnetic field simulation software, the performance of the accelerating structure under different size parameters is simulated to determine the optimal inner diameter, outer diameter and axial length, so as to improve the efficiency of the accelerating structure.
[0031] In the embodiment, the low-loss ceramic dielectric ring can adopt a uniform dielectric ring, and the material is selected from high-purity alumina or magnesia ceramic. These two materials have the advantages of low loss and high dielectric constant, which can meet the requirements of the dielectric material for the accelerating structure. A composite or gradient dielectric ring can also be used, which is composed of two or more low-loss ceramic materials. Through the combination of different materials, the performance of the dielectric ring is further optimized. In addition, microchannels for liquid cooling can be integrated inside the low-loss ceramic dielectric ring or at the interface with the metal to solve the heat dissipation problem of the accelerating structure under high power working.
[0032] In this embodiment, the split seams are linear seams, and the total number of all split seams is 2. This design greatly reduces the discontinuous points that may cause electric field distortion and concentration, making the axial electric field (Ez) more uniform and concentrated at the acceleration gap. At the same time, the split low-loss ceramic dielectric body 2 has no insulating gap at the split surface that completely blocks the flow of dominant high-frequency current, allowing the dominant high-frequency current to flow continuously along the inner surface of the low-loss ceramic dielectric body 2, avoiding additional ohmic loss and parasitic mode excitation caused by current detouring or mode disturbance.
[0033] In this embodiment, the metal cavity 1 is usually made of oxygen-free copper or other materials, which has good electrical conductivity and mechanical properties. The metal cavity 1 is designed with a corresponding annular mounting groove for mounting the low-loss ceramic dielectric body 2. During assembly, the two half ceramic rings are precisely matched to form a complete dielectric ring, which is then embedded in the mounting groove of the metal cavity 1. Alternatively, the segmented assembly can be fixed by pressing. Between the low-loss ceramic dielectric body 2 and the metal cavity 1, a thin layer of transition material such as molybdenum sheet is provided as needed to improve the mechanical bonding and thermal conductivity between the two; Active metal brazing process can also be used to firmly connect the ceramic dielectric body 2 and the metal cavity 1 while maintaining the necessary RF contact.
[0034] Example 2: Deformation classified by split plane direction As described in Example 1, although axial splitting is the optimal implementation, in some special space-constrained cavities, the dielectric ring can also be split along a plane at an angle to the axis. This includes some irregularly shaped accelerating cavities, which can better adapt to the structure of the cavity by using oblique splitting (or oblique splitting). At this time, the shape of the interface needs to be specially optimized, and through precise geometric design and processing, the path change of the current when crossing the seam is minimized, and the influence on the continuity of the current is minimized.
[0035] In addition to the two-half structure, this embodiment can be extended to a complete dielectric ring composed of multiple (more than two) sector blocks. This includes four 90-degree sector blocks, but the seams are all axial. As long as the split seam does not constitute a ring-shaped interception of the surface current, it can be considered as an equivalent deformation of the present application.
[0036] In both embodiments 1 and 2, there are multiple installation methods, including fixing the low-loss ceramic medium body 2 in the metal cavity 1 by interference fit or external flange compression. This fixing method is simple and reliable, with low cost, and is suitable for some occasions where the assembly precision is not very high. The two halves of the ceramic ring are first connected to the metal part through soldering, and then assembled as a whole or vice versa. Brazing and diffusion welding can provide a more secure connection and ensure good contact between the ceramic medium body 2 and the metal cavity 1, suitable for high-power and high-reliability accelerating structures. In the case of ultra-high vacuum and precision machining, the position is maintained by the self-positioning structure and the cavity constraint. This fixing method requires very high machining precision, but can avoid the impurities and performance effects that adhesives may bring, and is suitable for accelerating structures with very high vacuum and cleanliness requirements.
[0037] Embodiment 3: Method for manufacturing a two-half symmetrical structure low-loss ceramic medium auxiliary accelerating structure This embodiment provides a method for manufacturing a two-half symmetrical structure low-loss ceramic medium auxiliary accelerating structure, the specific steps are as follows: S1, machining ceramic medium parts According to the design requirements, at least two ceramic medium parts are machined. In this embodiment, two half-ring bodies are machined, and the medium cylindrical body is symmetrically divided along the plane containing the axis of the ring. During machining, high-precision machining equipment and processes are used to ensure the dimensional accuracy and surface quality of the two half-ring bodies. This includes using a numerical control machining center for cutting and polishing to ensure the flatness and perpendicularity of the split surface.
[0038] Then, a precise positioning structure is machined on the abutting surface of the two half-ring bodies, using a boss and groove matching structure. Through precise molds and machining processes, the size tolerance of the boss and groove is controlled within a very small range to ensure accurate alignment during assembly.
[0039] According to the electromagnetic field simulation results of the supported acceleration mode (TM020-π mode), the inner diameter, outer diameter and axial length of the low-loss ceramic medium ring are optimized and designed, and are machined according to the designed size. At the same time, according to the actual needs, select the appropriate ceramic material, such as high-purity alumina or magnesia ceramic, or prepare a composite or gradient medium ring, which can also integrate micro-channels for liquid cooling.
[0040] S2, split and assemble the ceramic medium body 2 The two half-ring bodies are assembled into the ceramic dielectric body 2 in such a way that the extension direction of the spliced joint between the components is approximately parallel to the direction of the dominant high-frequency current flow of the inner surface when the accelerating structure is in operation. During the splicing process, the positioning structure on the butt joint surface is used for accurate positioning to ensure that the two half-ring bodies can be tightly attached to form a seamless cylindrical inner surface and outer surface. The splicing quality is checked by visual inspection and measurement tools to ensure that the width and straightness of the spliced joint meet the design requirements.
[0041] S3, installing the ceramic dielectric body 2 The assembled ceramic dielectric body 2 is installed in the metal cavity 1. The metal cavity 1 is provided with a corresponding annular mounting groove, and the installation can be performed by embedding the whole into the annular mounting groove or by assembling and pressing and fixing in sections. During the installation process, attention should be paid to protect the surfaces of the ceramic dielectric body 2 and the metal cavity 1 to avoid scratching and collision.
[0042] S4, interface processing According to the needs, a thin layer of transition material or an active metal brazing process is provided between the ceramic dielectric body 2 and the metal cavity 1. In this embodiment, a thin layer of transition material such as a molybdenum sheet is used, which is placed between the ceramic dielectric body 2 and the metal cavity 1, and then tightly contacted through pressing and other methods to improve the mechanical bonding and heat conduction performance between the two. When using the active metal brazing process, the appropriate filler metal and welding parameters are selected to firmly connect the ceramic dielectric body 2 and the metal cavity 1 together while maintaining the necessary radio frequency contact.
[0043] Through the above embodiments and manufacturing methods, the two half-symmetrical structure low-loss ceramic dielectric auxiliary accelerating structure of the present application can realize the particle acceleration function of low loss, high stability and high reliability, and provides an effective solution for the development of particle accelerator technology. Those skilled in the art should understand that the above embodiments are only used to illustrate the present application and should not be considered as limiting the present application, and various changes and modifications can be made to the above embodiments without departing from the spirit and scope of the present application.
Claims
1. A low-loss ceramic dielectric-assisted acceleration structure with a two-half symmetrical structure, comprising a metal cavity and a low-loss ceramic dielectric body disposed therein, characterized in that, The low-loss ceramic dielectric body is composed of at least two ceramic dielectric components joined together, and the extension direction of the joint between the ceramic dielectric components is approximately parallel to the flow direction of the dominant high-frequency current on the inner surface of the acceleration structure in the working mode.
2. The low-loss ceramic dielectric-assisted acceleration structure with a two-half symmetrical structure according to claim 1, characterized in that, The low-loss ceramic dielectric body is ring-shaped, and the at least two ceramic dielectric components are two semi-rings, which are symmetrically divided and joined along a plane containing the axis of the ring.
3. The low-loss ceramic dielectric-assisted acceleration structure with a two-half symmetrical structure according to claim 2, characterized in that, The mating surfaces of the two semi-rings are provided with a precision positioning structure, which is a boss and groove matching structure to ensure accurate alignment during assembly and form a seamless cylindrical inner and outer surface.
4. The low-loss ceramic dielectric-assisted acceleration structure with a two-half symmetrical structure according to claim 2, characterized in that, The splicing seam is a straight joint, and the total number of all splicing seams is N, where 2≤N≤6, preferably 2.
5. The low-loss ceramic dielectric-assisted acceleration structure with a two-half symmetrical structure according to claim 2, characterized in that, The assembled low-loss ceramic dielectric body has no insulating gap at the splicing surface that completely blocks the flow of the dominant high-frequency current, allowing the dominant high-frequency current to flow continuously along the inner surface of the low-loss ceramic dielectric body.
6. The low-loss ceramic dielectric-assisted acceleration structure with a two-half symmetrical structure according to claim 2, characterized in that, The inner diameter, outer diameter, and axial length of the low-loss ceramic dielectric ring are optimized based on the electromagnetic field simulation results of the supported acceleration mode, which is the TM020-π mode.
7. The low-loss ceramic dielectric-assisted acceleration structure with a two-half symmetrical structure according to claim 2, characterized in that, The low-loss ceramic dielectric ring is a uniform dielectric ring made of high-purity alumina or magnesium oxide ceramic; or the low-loss ceramic dielectric ring is a composite or gradient dielectric ring composed of two or more low-loss ceramic materials; or microchannels for liquid cooling are integrated inside the low-loss ceramic dielectric ring or at the interface with the metal.
8. The low-loss ceramic dielectric-assisted acceleration structure with a two-half symmetrical structure according to any one of claims 1-7, characterized in that, The metal cavity is designed with a corresponding annular mounting groove, and the low-loss ceramic dielectric body is integrally embedded in the annular mounting groove, or is assembled in sections and then pressed together for fixation; a thin layer of transition material is provided between the low-loss ceramic dielectric body and the metal cavity, or an active metal brazing process is used.
9. A method for manufacturing a low-loss ceramic dielectric-assisted acceleration structure with a two-half symmetrical structure, characterized in that, include: At least two ceramic dielectric components were manufactured; The components are assembled into a ceramic dielectric body in such a way that the extension direction of the splicing seam between the components is approximately parallel to the direction of the dominant high-frequency current flow on the inner surface of the acceleration structure during operation. The assembled ceramic dielectric body is installed in the metal cavity, which is provided with a corresponding annular mounting groove. The installation method is either to embed the whole into the annular mounting groove or to fix it by pressing after segmented assembly. A thin layer of transition material or an active metal brazing process is provided between the ceramic dielectric body and the metal cavity as needed.
10. The method for manufacturing a low-loss ceramic dielectric-assisted acceleration structure with a two-half symmetrical structure according to claim 9, characterized in that, The at least two ceramic dielectric components are two semi-rings, and the dielectric cylinder is symmetrically divided along the plane containing the axis of the ring during processing; The mating surfaces of the two semi-rings are machined with a precision positioning structure, which is a boss and groove mating structure. The inner diameter, outer diameter, and axial length of the low-loss ceramic dielectric ring are optimized based on the electromagnetic field simulation results of the supported acceleration mode (TM020-π mode). The low-loss ceramic dielectric ring is a uniform dielectric ring made of high-purity alumina or magnesium oxide ceramic, or a composite or gradient dielectric ring, or integrated with microchannels for liquid cooling. The method of fixing the assembled ceramic dielectric body into the metal cavity is one of mechanical clamping, brazing or diffusion welding, or adhesive-free precision fitting.