Button-type signal feed-through for beam position detector and preparation method of button-type signal feed-through

Abstract

The invention provides a button type signal feed-through for a beam position detector. The button type signal feed-through comprises a shell, a composite unit and an insulator. The composite unit comprises a button electrode and an inner conductor, and the button electrode is suitable for sensing an electromagnetic field signal generated by charged particle beams in the vacuum cavity; the inner conductor vertically and integrally extends from the center of the button electrode, a flange is arranged near one end, close to the button electrode, of the inner conductor, and the inner conductor is suitable for transmitting beam electromagnetic field signals. The insulator is sleeved on the inner conductor and comprises a first section cylinder and a second section cylinder, and the front end face of the first section cylinder is welded and fixed with the flange of the inner conductor; the second section of cylinder body extends outwards in the radial direction from the rear end of the first section of cylinder body, the circumferential outer surface of the second section of cylinder body is welded and fixed with the shell, and the insulator is suitable for fixed support and electrical insulation, so that smooth transition of transmission impedance and vacuum sealing are realized. The invention further provides a preparation method of the charged particle beam position detector and a charged particle beam position detector structure.

Description

Technical Field

[0001] This invention relates to the field of particle accelerator technology, and in particular to a button-type signal feedthrough for a beam position detector in a vacuum environment, its fabrication method, and a structure for a charged particle beam position detector. Background Technology

[0002] Beam Position Monitors (BPMs) are indispensable beam diagnostic devices in particle accelerators. Their core function is to monitor the beam's positional deviation within the vacuum cavity in real time, providing crucial data for the accelerator's feedback or closed-track correction systems, thereby optimizing the beam trajectory and improving operational efficiency and stability. Among the BPM's components, the signal feedthrough, which senses the beam's electromagnetic field signal through symmetrically arranged electrodes, has become the mainstream technology for achieving high-resolution beam position measurement. However, related technologies still face the challenge of balancing structural complexity with fabrication consistency. Especially when facing the extreme conditions of next-generation accelerators (such as smaller beam size, higher resolution, better accuracy, lower permeability, and ultra-high vacuum), the limitations of traditional signal feedthrough fabrication methods become increasingly apparent.

[0003] Currently, button signal feedthroughs typically consist of four parts: a button electrode, an inner conductor, an insulator, and a housing. In terms of structural design, traditional solutions often employ a split-type needle-shaped signal feedthrough, where the button electrode is fixed to the front end of a needle-shaped conductor via welding or mechanical assembly. While this design can achieve basic signal transmission, it has significant drawbacks in practical applications: for example, the electrode welding process easily leads to deformation and surface unevenness; the gap between the needle-shaped conductor or electrode and the housing is difficult to control precisely, resulting in problems such as capacitance parameter drift and increased signal reflection. Regarding material selection, traditional signal feedthroughs typically use stainless steel for the housing and titanium alloy for the inner conductor, while the insulator relies on alumina ceramic (Al2O3). To improve brazing bond strength, nickel plating is commonly applied to the interface between the housing and the ceramic. However, the magnetism of nickel (relative permeability μ≈100~600) significantly increases the overall permeability of the signal feedthrough, interfering with the local magnetic field distribution of the beam and affecting measurement accuracy.

[0004] In summary, the shortcomings of signal feedthrough technology in terms of structural accuracy, material compatibility, and signal integrity have become key bottlenecks restricting the performance improvement of constrained flow position detectors. Summary of the Invention

[0005] In view of this, to solve at least one technical problem mentioned above and in other aspects of the related art, the present invention proposes a button-type signal feedthrough, comprising a housing, a composite unit, and an insulator. Specifically, the housing is configured to be installed in radially symmetrical detection holes in a vacuum cavity. The composite unit includes a button electrode and an inner conductor; the button electrode is suitable for sensing electromagnetic field signals generated by a charged particle beam in the vacuum cavity; the inner conductor extends vertically and integrally from the center of the button electrode, and a flange is provided near one end of the inner conductor close to the button electrode, and the inner conductor is suitable for transmitting electromagnetic field signals. The insulator is sleeved on the inner conductor and includes a first cylindrical section and a second cylindrical section: the front end face of the first cylindrical section is welded and fixed to the flange of the inner conductor; the second cylindrical section extends radially outward from the rear end of the first cylindrical section, and the circumferential outer surface of the second cylindrical section is welded and fixed to the housing, the insulator is suitable for fixed support and electrical insulation, realizing a smooth transition of transmission impedance and vacuum sealing.

[0006] According to an embodiment of the present invention, the housing includes a positioning ring disposed on the outer peripheral surface of the housing near the button electrode to position the housing relative to the detection hole. The positioning ring is suitable for determining the position of the button electrode measuring end face in the axial and circumferential directions of the vacuum cavity, thereby suppressing positional errors. A plurality of venting grooves extending in the axial direction parallel to the composite unit are formed on the positioning ring to discharge residual gas between the outer wall of the housing and the detection hole.

[0007] According to an embodiment of the present invention, the aforementioned button-type signal feedthrough further includes a wiring port and a positioning structure. The wiring port protrudes radially along the outer circumference of the vacuum cavity, suitable for engaging with an external mating port to output the electromagnetic field signal of the beam; the positioning structure is disposed at one end of the wiring port on the outer shell and protrudes radially along the circumference to engage with the vacuum cavity, thereby limiting the position and angle of the button-type signal feedthrough on the vacuum cavity. The positioning structure is suitable for determining that the measuring end face of the button electrode is tangent to the inner wall of the vacuum cavity and suppressing angular errors.

[0008] According to an embodiment of the present invention, a groove is formed on the outer casing and between the inner conductor flange and the button electrode to form a stress groove, which is suitable for preventing welding stress concentration.

[0009] According to an embodiment of the present invention, the welding surface between the front end face of the first section of the insulator and the inner conductor flange, and the welding surface between the circumferential outer surface of the second section of the insulator and the outer shell, are metallized interfaces.

[0010] According to an embodiment of the present invention, the main component of the metallized interface material includes a molybdenum-manganese alloy.

[0011] In another aspect of the present invention, a method for preparing the aforementioned button-type signal feedthrough is also provided, comprising:

[0012] A composite unit is provided, comprising a button electrode and an inner conductor with a flange;

[0013] The ceramic material is shaped to obtain a coaxial first section and a second section of cylinder. The diameter of the second section of cylinder is larger than that of the first section of cylinder. The front end face of the first section of cylinder and the circumferential outer surface of the second section of cylinder are metallized to obtain an insulator.

[0014] Insert the composite unit with an insulator fitted onto the inner conductor into the outer shell;

[0015] The front end face of the first section of the cylinder, after metallization, is welded and fixed to the flange of the inner conductor through vacuum brazing process, and the circumferential outer surface of the second section of the cylinder, after metallization, is welded and fixed to the outer shell.

[0016] According to an embodiment of the present invention, the vacuum brazing process includes: fixing the positions of the outer shell, insulator, and composite unit with brazing material, heating to 800~1000°C in a vacuum environment and holding for 10~30 minutes, then cooling to room temperature, and plating nickel at the brazing positions of the outer shell and inner conductor, with a nickel layer thickness of less than 8μm.

[0017] In another aspect of the invention, a charged particle beam position detector is also proposed, comprising a vacuum cavity and the aforementioned button-type signal feedthroughs. The vacuum cavity is suitable for providing a vacuum-sealed environment, and multiple detection holes are symmetrically arranged and radially extended on the same radial circumference of the vacuum cavity; the multiple button-type signal feedthroughs are respectively installed in the detection holes.

[0018] According to an embodiment of the present invention, the measuring surface of the button electrode of the button-type signal feedthrough is tangent to the inner wall of the vacuum cavity.

[0019] According to embodiments of the present invention, the button electrode and inner conductor of the button-type signal feedthrough proposed in this invention adopt an integral molding structure, eliminating the deformation and gap deviation introduced by welding or assembly in traditional split components. The flange of the extended portion of the inner conductor and the flange inside the stress groove of the outer shell are precisely welded to the insulator to form a stable rigid fixed support, which not only enhances mechanical strength and stability, but also ensures the flatness of the button electrode surface, its perpendicularity to the axis, and the gap tolerance with the outer shell, thereby significantly reducing beam coupling impedance and signal measurement error, and improving the consistency of electrical parameters. The insulator consists of a first cylindrical section and a second cylindrical section, which respectively undertake the functions of fixing and supporting the inner conductor, providing electrical insulation, and vacuum sealing between the inner conductor and the outer shell, realizing a smooth transition of transmission impedance. The flange of the first cylindrical section is precisely matched with the inner conductor; the second cylindrical section extends radially and is welded to the outer shell to form a double-layer sealing interface, taking into account both vacuum sealing performance and structural stability. Attached Figure Description

[0020] Figure 1 This is an axial cross-sectional view of the button-type signal feedthrough in an embodiment of the present invention;

[0021] Figure 2 This is an axial cross-sectional view of the composite unit in an embodiment of the present invention.

[0022] Figure 3 This is a radial view of the button-shaped signal feedthrough measurement surface in an embodiment of the present invention;

[0023] Figure 4 This is an external structural diagram of the button-type signal feedthrough housing in an embodiment of the present invention;

[0024] Figure 5 This is an axial cross-sectional view of the button-type signal feedthrough housing in an embodiment of the present invention;

[0025] Figure 6 This is an axial cross-sectional view of the vacuum cavity in an embodiment of the present invention;

[0026] Figure 7 This is a cross-sectional view of the charged particle beam position detector in an embodiment of the present invention;

[0027] Figure 8 This is an axial cross-sectional view of the insulator in an embodiment of the present invention;

[0028] Figure 9 This is a temperature-time curve of vacuum brazing during the fabrication of the button-shaped signal feedthrough according to the present invention;

[0029] Figure 10 This is the time-domain signal used in the button-type signal feedthrough in this embodiment of the invention;

[0030] Figure 11 This is a simulation result diagram of the characteristic impedance time domain reflectometry (TDR) of the button-type signal feedthrough in an embodiment of the present invention.

[0031] Figure 12 This is a graph showing the test results of the button-type signal feedthrough characteristic impedance of the present invention.

[0032] In the accompanying drawings of this invention, the reference numerals have the following meanings:

[0033] 1-Button-type signal feedthrough; 11-Housing; 111-Vent groove; 112-Positioning ring; 113-Positioning structure; 114-First stress groove; 115-Electrical connector; 121-Button electrode; 122-Inner conductor; 123-Flange; 124-Second stress groove; 13-Insulator; 132-First metallization interface; 133-Second metallization interface; 2-Vacuum cavity; 21-Detection hole; 22-Limiting structure; P-Wiring port. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0035] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0036] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The terms “comprising,” “including,” etc., as used herein indicate the presence of features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0037] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0038] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. Where the terms "first," "second," etc., are used throughout the text, they are used only to distinguish similar objects and should not be construed as indicating or implying their relative importance, order of precedence, or implicitly specifying the number of technical features indicated. It should be understood that the data in the descriptions of "first," "second," etc., can be interchanged where appropriate.

[0039] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0040] In the description of this invention, it should be understood that the terms "longitudinal", "length", "circumferential", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the subsystem or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0041] Throughout the accompanying drawings, identical elements are represented by the same or similar reference numerals. Conventional structures or configurations may be omitted where they might cause confusion in understanding the invention. Furthermore, the shapes, dimensions, and positional relationships of the components in the drawings do not reflect actual size, scale, or actual positional relationships. Additionally, any reference symbols placed within parentheses in this invention should not be construed as limiting the scope of the invention.

[0042] Similarly, to simplify the invention and aid in understanding one or more of the various disclosed aspects, in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together into a single embodiment, figure, or description thereof. The use of terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicates that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0043] Furthermore, the technical solutions of the various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0044] In the process of realizing this invention, it was discovered that traditional split-type pin-type feedthroughs suffer from deformation and gap errors due to the assembly of multiple components. However, this invention, through integrated structural design, optimized material properties and non-magnetic selection, and precision manufacturing innovation, achieves a comprehensive breakthrough in higher consistency, better stability, lower permeability, and ultra-high vacuum compatibility. While meeting signal strength requirements, the button electrode design minimizes beam coupling impedance, and impedance matching is performed between the electrode and the signal feedthrough structure connected to the external circuit to reduce signal reflection. The core inventive concept of this invention lies in systematically solving the technical bottlenecks of traditional button-type signal feedthroughs in terms of assembly accuracy, electrical characteristics, magnetic interference, and signal transmission efficiency through integrated structure, non-magnetic materials, and collaborative process design.

[0045] Figure 1 This is an axial cross-sectional view of the button-type signal feeder 1 in an embodiment of the present invention. Figure 2 This is an axial cross-sectional view of the composite unit in an embodiment of the present invention.

[0046] This invention proposes a button-type signal feedthrough 1, such as... Figure 1 As shown, the system includes a housing 11, a composite unit, and an insulator 13. Specifically, the housing 11 is configured to be installed in detection holes 21 arranged radially symmetrically in a vacuum chamber 2. The composite unit includes a button electrode 121 and an inner conductor 122, which are integrally formed. The button electrode 121 is used to sense the electromagnetic field signal generated by the charged particle beam in the vacuum chamber 2. The inner conductor 122 extends vertically and integrally from the center of the button electrode 121, and a flange 123 is provided near one end of the inner conductor 122 close to the button electrode 121. The inner conductor 122 is used to transmit the beam electromagnetic field signal. The insulator 13 is sleeved on the inner conductor 122 and includes a first cylindrical section and a second cylindrical section: the front end face of the first cylindrical section is welded and fixed to the flange 123 of the inner conductor; the second cylindrical section extends radially outward from the rear end of the first cylindrical section, and the circumferential outer surface of the second cylindrical section is welded and fixed to the housing 11. The insulator 13 is used for fixed support and electrical insulation, realizing a smooth transition of transmission impedance and vacuum sealing.

[0047] According to embodiments of the present invention, such as Figure 2 As shown, the button electrode 121 and inner conductor 122 of the button-type signal feedthrough proposed in this invention adopt an integral molding structure, eliminating the deformation and gap deviation introduced by welding or assembly in traditional split components. The flange 123 of the extended portion of the inner conductor 122 and the flange inside the first stress groove 114 of the outer shell 11 are precisely welded to the insulator 13 to form a stable rigid fixed support, which not only enhances mechanical strength and stability, but also ensures the flatness of the electrode surface, the perpendicularity to the axis, and the gap tolerance with the outer shell, thereby significantly reducing beam coupling impedance and signal measurement error, and improving the consistency of electrical parameters. The insulator 13 consists of a first cylindrical section and a second cylindrical section, which respectively undertake the fixed support and electrical insulation of the inner conductor 122, as well as the vacuum sealing function between the inner conductor 122 and the outer shell 11, realizing a smooth transition of transmission impedance. The first cylindrical section is precisely matched with the flange 123 of the inner conductor 122; the second cylindrical section extends radially and is welded to the outer shell 11 to form a double-layer sealing interface, taking into account both vacuum sealing performance and structural stability.

[0048] Specifically, the first flange 123 of the inner conductor 122 and the internal flange design near the first stress groove 114 of the outer shell 11 not only serve as welding reference surfaces for the insulator 13, but also enhance structural stability through rigid fixing supports, ensuring the flatness of the button electrode surface, its perpendicularity to the axis, and the clearance tolerance with the outer shell. The insulator 13 is manufactured using an integral ceramic molding process, with the first and second cylindrical sections seamlessly connected, eliminating assembly gaps and interface leakage risks associated with split structures. The stepped structure of the insulator 13 (the diameter of the first cylindrical section is smaller than that of the second cylindrical section) corresponds to the groove structure of the composite unit, which helps prevent abrupt structural changes. This gradually changing mechanical structure has high transmission efficiency and a small change in characteristic impedance, which helps reduce signal reflection and loss.

[0049] More specifically, the rounded corners at the transition of the 13-step insulator help reduce stress concentration and prevent high-temperature stress cracks during vacuum brazing.

[0050] Figure 3 This is a radial view of the measuring surface of the button-type signal feedthrough 1 in an embodiment of the present invention. Figure 4 This is an external structural diagram of the button-type signal feedthrough housing in an embodiment of the present invention. Figure 5 This is an axial cross-sectional view of the button-type signal feedthrough housing in an embodiment of the present invention.

[0051] According to embodiments of the present invention, such as Figure 3 , Figure 4 As shown, the housing 11 includes a positioning ring 112, which is disposed on the outer peripheral surface of the housing 11 near the button electrode 121 to position the housing 11 relative to the detection hole 21. The positioning ring 112 is suitable for determining the axial and circumferential positions of the measuring end face of the button electrode 121 and the vacuum chamber 2, thereby suppressing positional errors. Multiple venting grooves 111 extending in the axial direction parallel to the composite unit are formed on the positioning ring 112 to discharge residual gas between the outer wall of the housing and the detection hole 21.

[0052] According to an embodiment of the present invention, a positioning ring 112 is disposed on the outer peripheral surface of the housing 11 near the button electrode 121. Its outer diameter is precisely matched with the inner diameter of the detection hole 21, achieving radial positioning of the housing 11 through mechanical dimensions and avoiding installation position offset. Simultaneously, the end face of the positioning structure 113 is in contact with the end face of the detection hole limiting structure 22, restricting axial displacement and ensuring that the measuring surface of the button electrode 121 is strictly tangent to the inner wall of the vacuum chamber 2, while suppressing angular errors. Multiple venting grooves 111 parallel to the axial direction of the composite unit are uniformly distributed circumferentially along the positioning ring 112, forming a gas diffusion channel to accelerate the discharge of residual gas (such as gas stored in the structural space or material venting) between the outer wall of the housing and the detection hole 21. The continuous distribution of the venting grooves 111 breaks the closed gap structure, reducing slow venting caused by local high-pressure areas formed by gas retention, ensuring an ultra-high vacuum environment within the vacuum chamber 2, and improving the accuracy of beam position measurement.

[0053] In some specific embodiments, the venting groove 111 may have a U-shaped or rectangular cross-section, and the edges of the groove are chamfered to prevent damage to the surface finish of the inner surface of the vacuum chamber.

[0054] In some specific embodiments, an electrical connector 115 is also provided on the outer peripheral surface near the terminal P. The connector can be in the form of a thread, snap-fit, or nested structure to achieve a stable and reliable electrical connection and efficient signal transmission.

[0055] In some specific embodiments, the diameter of the button electrode is adjusted according to the actual application. The specific dimensions shown in this invention are only examples and are not the only determined choices. Other electrode diameter choices should also be within the scope of protection of this patent. At the same time, the gap between the button electrode 121 and the housing 11 should be as small as possible to reduce coupling impedance. However, due to limitations in the manufacturing process, it is difficult to achieve a smaller gap while ensuring electrical characteristics.

[0056] In some specific embodiments, in the button-type signal feedthrough 1 proposed in this invention, the diameter of the button electrode 121 is 6 mm, and the gap between the button electrode 121 and the outer shell 11 is 250 μm; the composite unit and the outer shell 11 are insulated, and the insulation resistance is greater than 10 Ω. 8 The Ohm (DC500V) composite unit has a characteristic impedance of 50Ω and is vacuum-sealed via insulator 13, with a vacuum leakage rate of less than 2×10⁻⁶. -11 mbar×L / s (He).

[0057] In some specific embodiments of the present invention, the outer shell 11 is required to be non-magnetic or low-magnetic to reduce the influence on the charged beam and the nearby magnetic field. Stainless steel, titanium, etc. are commonly used. In the present invention, the outer shell 11 can be made of non-magnetic stainless steel (such as 316LN), whose low permeability (μ<1.01) helps to avoid interference with the beam and magnetic field. At the same time, the high ductility of the material supports the precision machining of the venting groove 111, ensuring dimensional accuracy and surface finish.

[0058] In some specific embodiments, the button electrode 121 and the inner conductor 122 are used to measure and transmit electromagnetic field signals. Their conductivity, thermal conductivity, and coefficient of linear expansion need to be considered. Higher thermal conductivity increases heat dissipation and reduces deformation; materials such as titanium, molybdenum, stainless steel, and copper are typically chosen. In this invention, the button electrode 121 and the inner conductor 122 of the button-type signal feedthrough are made of molybdenum. Molybdenum is non-magnetic, has good electrical and thermal conductivity, and low activity. This avoids the problem of titanium vapor not escaping easily (small gap) during vacuum brazing of titanium materials, which could lead to short circuits on the vapor-deposited ceramic surface. Furthermore, it has poor machinability.

[0059] In some specific embodiments, the insulator 13 serves as a fixed support, electrical insulation, and vacuum seal. It requires overall density and uniformity. A smaller dielectric constant can increase the frequency of capturing higher-order modes and reduce tail field impedance. Commonly used materials include alumina ceramics, zirconium oxide, aluminum nitride, silicon carbide, boron carbide, and silicon dioxide. The button-type signal feedthrough insulator 13 proposed in this invention uses ceramic (99.5% aluminum oxide content). Ceramic is abundant, has stable performance, high mechanical strength, good insulation properties, and high thermal shock resistance. Furthermore, the process is simple and mature, with a short processing cycle. As the aluminum oxide content increases, the thermal conductivity also gradually increases. Higher purity results in more uniform material and a more stable dielectric constant.

[0060] According to embodiments of the present invention, such as Figure 4 , Figure 5 As shown, the aforementioned button-type signal feeder 1 also includes a wiring port P and a positioning structure 113. The wiring port P protrudes radially along the vacuum cavity 2 and is suitable for engaging with an external mating port to output a beam electromagnetic field signal; the positioning structure 113 is disposed at the front end of the wiring port P and protrudes radially to engage with the vacuum cavity 2, thereby limiting the position of the button-type signal feeder 1 on the vacuum cavity 2.

[0061] According to an embodiment of the present invention, the wiring port P extends directly radially along the vacuum cavity 2, forming the shortest connection path with the inner conductor 122, reducing parasitic capacitance and inductance in signal transmission and lowering high-frequency signal loss. The positioning structure 113 (such as a boss or a snap-fit) protrudes radially along the wiring port P and mates with the pre-machined groove on the inner wall of the vacuum cavity 2 or the detection hole 21. By limiting the circumferential and axial displacement of the signal feedthrough through mechanical dimensions, it ensures that the measuring surface of the button electrode 121 is strictly tangent to the inner wall of the vacuum cavity 2 and suppresses angular errors.

[0062] Figure 6 This is an axial cross-sectional view of the vacuum cavity 2 in an embodiment of the present invention. Figure 7 This is a cross-sectional view of the charged particle beam position detector in an embodiment of the present invention.

[0063] In some specific embodiments, such as Figure 7 As shown, the positioning structure 113 is a boss, and the inlet of the detection hole 21 of the vacuum cavity 2 is provided with a limiting structure 22. The two work together to limit the position of the button-type signal feedthrough, ensuring that the measuring end face of the button electrode is tangent to the inner wall of the vacuum cavity and suppressing angular errors.

[0064] According to an embodiment of the present invention, a first stress groove 114 is formed in the recess of the outer casing 11, and a second stress groove 124 is formed between the inner conductor flange 123 and the button electrode 121, which is suitable for preventing welding deformation and stress concentration. Figure 5 The first stress groove 114 and Figure 2 The location of the second stress groove 124 is shown schematically. More specifically, the two metallized brazing surfaces of the insulating ceramic, corresponding to the first stress groove 114 of the outer shell and the second stress groove 124 of the composite unit, are stress-relieving structures to reduce deformation and stress.

[0065] According to embodiments of the present invention, both the first stress groove 114 and the second stress groove 124 can be U-shaped or V-shaped grooves, located near the welding interface. Their arc-shaped or sharp-cornered structure can guide the dispersion of welding thermal stress along the groove body, avoiding the formation of localized high-stress zones near the weld. During welding, the solidification shrinkage of the brazing filler metal (such as gold-copper or silver-copper alloys) easily leads to interface stress concentration. The first stress groove 114 and the second stress groove 124 significantly reduce the generation of microcracks by absorbing some of the shrinkage strain, improving weld integrity and ensuring vacuum sealing performance.

[0066] Figure 8 This is an axial cross-sectional view of the insulator in an embodiment of the present invention.

[0067] According to embodiments of the present invention, such as Figure 8As shown, the welding surface (first metallization interface 132) between the front end face of the first section of the cylinder and the flange 123, and the welding surface (second metallization interface 133) between the circumferential outer surface of the second section of the cylinder and the outer shell 11 are metallization interfaces.

[0068] According to embodiments of the present invention, metallization treatment (such as the molybdenum-manganese method) forms a dense metal layer on the ceramic surface, realizing the metallurgical bonding between ceramic and metal, avoiding the interface weakening problem of traditional ceramic-metal direct welding, and greatly improving the welding strength; the metallization layer fills the micropores between ceramic and metal, forming a continuous sealing interface, ensuring the sealing performance of the component in an ultra-high vacuum environment.

[0069] According to an embodiment of the present invention, the two metallized brazing surfaces of the insulating ceramic, corresponding to the first stress groove 114 of the outer shell and the second stress groove 124 of the composite unit, are both for reducing deformation and stress.

[0070] According to an embodiment of the present invention, the main component of the metallized interface material is a molybdenum-manganese alloy. Specifically, the molybdenum-manganese alloy may also be doped with other modifying elements.

[0071] In another aspect of the present invention, a method for preparing the aforementioned button-type signal feedthrough 1 is also provided, comprising the following steps S101-S104:

[0072] Step S101: Provide a composite unit, the composite unit including a button electrode 121 and an inner conductor 122 having a flange 123;

[0073] Step S102: Shape a ceramic material (e.g., alumina ceramic) to obtain a coaxial first section and second section of cylinder. The diameter of the second section of cylinder is larger than that of the first section of cylinder. Metallize the front end face of the first section of cylinder and the circumferential outer surface of the second section of cylinder to obtain insulator 13.

[0074] Step S103: Insert the composite unit with an insulator on the inner conductor into the outer shell 11;

[0075] Step S104: Prepare the outer shell 11, and fix the front end face of the metallized first section of the cylinder to the inner conductor 122 by vacuum brazing, and fix the circumferential outer surface of the metallized second section of the cylinder to the outer shell 11 to obtain the button-type signal feedthrough 1.

[0076] According to embodiments of the present invention, the preparation method proposed in this invention achieves a unified approach of high-precision processing, lower welding stress, and non-magnetic performance through the integrated structure of the button electrode 121 and the inner conductor 122, the metallization of the insulator 13, and the synergistic optimization of vacuum brazing process. This systematically overcomes the limitations of traditional processes in terms of assembly errors, poor electrical characteristics, sealing failure, and magnetic interference.

[0077] In some specific embodiments, after step S102 is completed, nickel may be plated at the ceramic metallization interface corresponding to the composite unit and the shell, and the nickel layer thickness is controlled to be less than 8 μm.

[0078] In some specific embodiments, the outer shell 11 may be formed using a flanged structure.

[0079] Specifically, the integrated molding of the button electrode 121 and the inner conductor 122 (such as CNC turning or powder metallurgy) eliminates the assembly errors of traditional split structures, ensuring the flatness of the electrode surface. Alumina ceramic is processed into a coaxial first section (smaller diameter) and second section (larger diameter) using isostatic pressing or grinding processes, naturally adapting to impedance matching requirements with its stepped structure. The front end face of the first section and the circumferential outer surface of the second section are metallized using a molybdenum-manganese method, forming a first metallization interface 132 and a second metallization interface 133, respectively. The metallization layer enhances the wettability between the ceramic and the metal, and by staggering the welding interface direction, welding thermal stress is buffered, preventing interface cracking. The metallization interfaces are welded in a vacuum environment using brazing filler metal with gold-copper or silver-copper as the main components. The nickel layer thickness is controlled through a nickel plating process at the composite unit and shell welding interface to avoid magnetic contamination introduced by traditional nickel plating processes, ensuring that the overall relative permeability μ of the component is less than 1.02, guaranteeing the accuracy of beam current measurement.

[0080] In some specific embodiments, the main process methods for forming the first metallization interface 132 and the second metallization interface 133 include the molybdenum-manganese method, direct copper plating method, active metal brazing method, thick film metallization technology, chemical plating metallization method, and DBA method. This invention selects the mature and widely used molybdenum-manganese method. In the molybdenum-manganese method, manganese is oxidized to MnO in hydrogen gas containing more than 0.001% water by volume. This oxidation is completed at around 800°C. At high temperatures, it dissolves into the glass phase, reducing its viscosity. This low-viscosity glass phase penetrates into the voids of the molybdenum layer on one hand and into the ceramic body on the other. Due to the dissolution and recrystallization process of Al2O3 in the glass phase, large corundum crystals often precipitate at the interface. MnO can not only dissolve into the glass phase but also react with Al2O3 to form manganese aluminum spinel or with SiO2 to form rhodochrosite. Molybdenum begins to sinter at high temperatures, forming a porous sintered layer, while the surface of molybdenum is slightly oxidized in moist hydrogen. This trace amount of oxide can dissolve in the glass phase that penetrates into the pores of the metallization layer, giving the glass phase good wettability to molybdenum. The molybdenum particles encapsulated in the glassy material are well sintered and gradually migrate towards the ceramic body. After cooling, the metal phase layer is tightly bonded to the ceramic body through the filtration zone. Due to the high-temperature reaction described above, an intermediate layer of a certain thickness is formed between the alumina ceramic and the molybdenum-manganese metallization layer. When the metallization layer thickness is about 50 μm, the intermediate layer thickness is about 30 μm. As the metallization layer thickness increases, the intermediate layer also thickens.

[0081] Figure 9 This is a temperature-time curve relationship diagram of vacuum brazing during the preparation of the button-type signal feeder 1 in this invention.

[0082] According to an embodiment of the present invention, the vacuum brazing process includes: fixing the positions of the outer shell 11 (the brazing material includes, but is not limited to, gold-copper or silver-copper, and may optionally incorporate other elements for modification), the composite unit, and the insulator 13 using brazing material, such as... Figure 9 As shown, the temperature is raised to 800~1000℃ in a vacuum environment and held for 10~30 minutes, and then cooled to room temperature. The nickel plating at the brazing positions of the outer shell 11 and the inner conductor 122 should have a nickel layer thickness of less than 8μm.

[0083] According to embodiments of the present invention, brazing under vacuum protection effectively isolates oxygen and reactive gases, prevents oxidation of the welding interface, ensures the fluidity and cleanliness of the brazing filler material, and reduces defects such as porosity and slag inclusions. Brazing materials with gold-copper or silver-copper as the main component possess excellent performance, suitable melting point, good wetting and gap-filling ability, and exhibit excellent strength, conductivity, and corrosion resistance of both the brazing material and the brazing interface. They are suitable for high-temperature (800~1000℃) and vacuum (<10℃) environments. -4The brazing environment (Pa) ensures the long-term reliability of the weld under extreme conditions (such as high-temperature baking at 220℃). The 800~1000℃ heating range is adapted to the melting characteristics of gold-copper or silver-copper based brazing fillers (e.g., the melting point of gold-copper based brazing fillers is 850~910℃, and the melting point of silver-copper based brazing fillers is 780~850℃, both lower than the base material), ensuring that the brazing filler fully melts and wets the base material, while avoiding grain coarsening or deformation caused by overheating of the base material. The 10~30 minute holding time balances the requirements of brazing filler diffusion and interfacial reaction, promoting the formation of metallurgical bonding while avoiding excessive reaction leading to the formation of brittle phases. During the slow cooling from high temperature to room temperature, a gradient cooling strategy (such as programmed temperature control) effectively disperses thermal stress, preventing interfacial cracking or deformation between the ceramic insulator 13 and the metal shell 11 due to thermal expansion mismatch.

[0084] In some specific embodiments, the nickel plating thickness at the brazing location is strictly limited to less than 8 μm, significantly reducing the magnetic contribution of nickel and ensuring that the overall relative permeability μ of the signal feedthrough is less than 1.02, thus avoiding interference with the beam current and magnetic field. The thin nickel layer can reduce the interfacial stress caused by the difference in thermal expansion coefficients between the ceramic and the substrate (such as stainless steel), enhance the bonding strength between the two, reduce the risk of welding hot cracking, and improve long-term stability.

[0085] Figure 6 This is an axial cross-sectional view of the vacuum cavity 2 in an embodiment of the present invention. Figure 7 This is a cross-sectional view of the charged particle beam position detector in an embodiment of the present invention.

[0086] In another aspect of the invention, a charged particle beam detector, such as... Figure 6 , Figure 7 As shown, it includes a vacuum chamber 2 and the aforementioned button-type signal feeders 1. The vacuum chamber 2 is suitable for sensing the passage of charged particle beams and providing a vacuum-sealed environment free from gas interference. Multiple detection holes 21 are symmetrically arranged and radially extended on the same radial circumference of the vacuum chamber 2; the multiple button-type signal feeders 1 are respectively installed in the detection holes 21.

[0087] In some specific embodiments, such as Figure 6 , Figure 7The vacuum cavity 2 shown has four symmetrically arranged and radially extending detection holes 21 on the same radial circumference. Four button-shaped signal feeders 1 are installed in the detection holes 21 and are symmetrically distributed at 90° around the circumference of the vacuum cavity 2, forming two pairs of orthogonal measurement channels (horizontal X, vertical Y). Differential signal processing is used to eliminate common-mode noise and improve the position resolution to the 10nm level. The positioning structure 113 (such as an annular boss and snap-fit ​​design) limits the position of the signal feeders by mechanical dimensions. Combined with the rigid fixing support of the flange 123 of the inner conductor 122 and the inner flange near the first stress groove of the outer shell 11, as well as the corresponding stress groove structure, it suppresses signal drift caused by structural or thermal deformation during the operation of the charged particle beam position detector.

[0088] In some specific embodiments, the detection holes 21 can be arranged symmetrically along the center of the vacuum cavity 2, and the spacing angle or the number of detection holes 21 is not limited.

[0089] In some specific embodiments, the radially protruding structure of the wiring port P is plug-and-play with external electronics systems, shortening the signal transmission path and reducing the influence of parasitic parameters.

[0090] According to an embodiment of the present invention, the measuring surface of the button electrode 121 of the button-type signal feed 1 is tangent to the inner wall of the vacuum cavity 2.

[0091] According to an embodiment of the present invention, the measuring surface of the button electrode 121 is tangent to the inner wall of the vacuum cavity 2, so that it is directly exposed to the transient electromagnetic field generated by the charged particle beam, reducing signal attenuation and distortion in the transmission path and improving sensing sensitivity. The tangent design avoids the existence of tail field impedance or dielectric gap between the electrode and the inner wall of the cavity, preventing signal noise introduced by gap capacitance or parasitic inductance, and ensuring high-fidelity capture of the original electromagnetic field signal.

[0092] It should be noted that the described embodiments are merely some, not all, of the embodiments of the present invention. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are all within the scope of protection of the present invention.

[0093] The button-type signal feeder 1 proposed in this invention was tested.

[0094] Figure 10 This refers to the time-domain signal used in the button-type signal feeder 1 in this embodiment of the invention. Figure 11 This is a simulation result diagram of the characteristic impedance time domain reflectometry (TDR) of the button-type signal feedthrough 1 in this embodiment of the invention. Figure 12 This is a graph showing the test results of the characteristic impedance of the button-type signal feedthrough 1 of this invention.

[0095] like Figure 10 As shown, during actual testing, the button-type signal feeder 1 in this embodiment of the invention meets the technical requirements and has a relatively fast detection sensitivity. Figure 11 , Figure 12 As can be seen from the comparison, the characteristic impedance of the button-type signal feedthrough 1 in the embodiment of the present invention is approximately the same as that of the TDR simulation results. The simulation model is consistent with the impedance of the actual product, indicating that the manufacturing process (such as precision machining, vacuum brazing, material treatment, etc.) and structural design of the button-type signal feedthrough 1 proposed in this invention have strict quality control capabilities. This not only verifies the closed-loop reliability from theoretical design to engineering implementation, but also demonstrates the comprehensive advantages of the component in precision manufacturing, signal transmission, and environmental tolerance.

[0096] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A button-type signal feeder, comprising: The outer casing is configured to be installed in the detection holes arranged radially symmetrically within the vacuum chamber; Composite unit, including: Button electrodes are suitable for sensing electromagnetic field signals generated by a beam of charged particles in the vacuum cavity; and An inner conductor extends vertically and integrally from the center of the button electrode, and a flange is provided near one end of the inner conductor close to the button electrode; and An insulator, sleeved on the inner conductor, and comprising: The first cylindrical section, the front end face of which is welded and fixed to the flange of the inner conductor; and The second cylindrical section extends radially outward from the rear end of the first cylindrical section. The circumferential outer surface of the second cylindrical section is welded and fixed to the outer shell. The insulator is suitable for fixed support and electrical insulation, realizing a smooth transition of transmission impedance and vacuum sealing.

2. The button-type signal feeder according to claim 1, wherein, The outer casing includes: A positioning ring is disposed on the outer peripheral surface of the housing near the button electrode to position the housing relative to the detection hole. The positioning ring is suitable for determining the axial and circumferential positions of the button electrode measuring end face in the vacuum cavity, thereby suppressing positional errors. Multiple venting grooves extending parallel to the axial direction of the composite unit are formed on the positioning ring to discharge residual gas between the outer wall of the housing and the detection hole.

3. The button-type signal feeder according to claim 1 further includes: The wiring port protrudes radially along the outer circumference of the vacuum cavity and is suitable for connection with external mating ports to output the beam electromagnetic field signal; A positioning structure is provided at one end of the wiring port of the housing and protrudes radially along the circumference to engage with the vacuum cavity, thereby limiting the position and angle of the button-type signal feed in the radial direction of the vacuum cavity; the positioning structure is suitable for determining that the measuring end face of the button electrode is tangent to the inner wall of the vacuum cavity and suppressing angular errors.

4. The button-type signal feeder according to claim 1, wherein, The groove on the outer casing and the stress groove formed between the inner conductor flange and the button electrode are designed to prevent welding stress concentration.

5. The button-type signal feeder according to claim 1, wherein, The welding surface between the front end face of the first cylindrical section and the inner conductor flange, and the welding surface between the circumferential outer surface of the second cylindrical section and the outer shell, are metallized interfaces.

6. The button-type signal feedthrough according to claim 5, wherein, The material of the metallized interface includes a molybdenum-manganese alloy.

7. A method for preparing a button-type signal feedthrough as described in any one of claims 1-6, comprising: A composite unit is provided, the composite unit comprising a button electrode and an inner conductor having a flange; A first cylindrical section and a second cylindrical section are obtained by shaping ceramic material. The diameter of the second cylindrical section is larger than that of the first cylindrical section. The front end face of the first cylindrical section and the circumferential outer surface of the second cylindrical section are metallized to obtain an insulator. Insert the composite unit with an insulator fitted onto the inner conductor into the outer shell; The front end face of the first section of the metallized cylinder is welded and fixed to the flange of the inner conductor by vacuum brazing, and the circumferential outer surface of the second section of the metallized cylinder is welded and fixed to the outer shell.

8. The method according to claim 7, wherein, The vacuum brazing process includes: fixing the positions of the outer shell, the insulator, and the composite unit with brazing material; heating the temperature to 800~1000℃ in a vacuum environment and holding it for 10~30 minutes; then cooling it to room temperature; and plating nickel at the brazing positions of the outer shell and the inner conductor, with the nickel layer thickness being less than 8μm.

9. A charged particle beam position detector structure, comprising: A vacuum chamber, suitable for providing a vacuum-sealed environment, wherein multiple detection holes are symmetrically arranged and radially extended on the same radial circumference; Multiple button-type signal feeders as described in any one of claims 1-6 are respectively installed in the detection hole.

10. The charged particle beam position detector structure according to claim 9, wherein, The measuring surface of the button electrode of the button-type signal feedthrough is tangent to the inner wall of the vacuum cavity.

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