Magnetic alloy loading cavity

Abstract

The invention belongs to the technical field of particle accelerators, and discloses a magnetic alloy loading cavity which comprises a cavity shell, an inner conductor assembly and a blind flange, the interior of the inner conductor assembly is a vacuum cavity, and two first cavities and a second cavity communicated between the two first cavities are formed between the inner conductor assembly and the cavity shell; the first cavity and the second cavity are filled with insulating gas. The inner conductor assembly comprises a vacuum pipeline, a ceramic ring and conducting rings, the conducting rings are connected to the two ends of the ceramic ring, and the vacuum pipeline is connected to the two ends of the ceramic ring through the conducting rings; the magnetic alloy loading cavity further comprises a through-wall assembly and a conductor, the through-wall assembly is connected to the peripheral side of the cavity shell so as to seal the second cavity, and the conductor sequentially penetrates through the through-wall assembly and the second cavity in an insulating mode and then is connected with the conducting ring. According to the magnetic alloy loading cavity, the structure can be kept compact under the extremely high gradient condition, sparking can be effectively restrained, and the voltage endurance capacity and the operation reliability of the magnetic alloy loading cavity are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of particle accelerator technology, and more particularly to a magnetic alloy loading cavity. Background Technology

[0002] Magnetic alloy loading cavities have important applications in particle synchrotrons, typically operating at frequencies above MHz and withstanding peak voltages on the order of kV. To ensure stable operation of the accelerating gap under high voltage and prevent cavity arcing, traditional designs often improve insulation by increasing the length of the insulating ceramic components.

[0003] However, with the increasing demands for cavity performance and compactness, it is necessary to further shorten the longitudinal dimension of the cavity. Under the new design goals, the cavity length directly limits the axial dimension of the insulating ceramic, accelerating the compression of the gap length. The length of the insulating ceramic component is also shortened accordingly. This change causes a significant increase in the voltage gradient per unit length, resulting in a significant increase in the risk of gap breakdown. Traditional single insulation methods are no longer sufficient to meet the stable operation requirements under high electric fields.

[0004] Therefore, there is an urgent need to provide a magnetic alloy loading cavity to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide a magnetic alloy loading cavity that can maintain a compact structure and effectively suppress arcing under extremely high gradient conditions, thereby significantly improving the pressure resistance and operational reliability of the magnetic alloy loading cavity.

[0006] A magnetic alloy loading cavity includes a cavity shell, an inner conductor assembly coaxially disposed inside the cavity shell, and blind flanges connecting the cavity shell and the inner conductor assembly at both axial ends. The interior of the inner conductor assembly is a vacuum cavity. Two first cavities are formed between the inner conductor assembly and the cavity shell, and a second cavity is connected between the two first cavities. Both the first cavity and the second cavity are filled with insulating gas. The inner conductor assembly includes a vacuum tube, a ceramic ring, and a conductive ring. Both ends of the ceramic ring are connected to the conductive ring, and the vacuum tube is connected to both ends of the ceramic ring through the conductive ring. The magnetic alloy loading cavity further includes a wall-penetrating assembly and a conductor. The wall-penetrating assembly is connected to the periphery of the cavity shell to seal the second cavity. The conductor passes through the wall-penetrating assembly and the second cavity in sequence and is then connected to the conductive ring.

[0007] As an optional solution, the number of the through-wall assembly and the conductor are both set to two and correspond one-to-one. The two conductors are arranged at intervals along the circular direction of the cavity shell and are respectively connected to different conductive rings. The central angle between the two conductors is 90 degrees.

[0008] As an optional solution, the through-wall assembly includes a first ceramic plate and a second ceramic plate arranged coaxially, and the conductor passes through the first ceramic plate and the second ceramic plate in sequence, forming a sealed cavity between the first ceramic plate and the second ceramic plate. The sealed cavity is filled with a cooling medium, and a medium inlet is provided on one side of the sealed cavity, and a medium outlet is provided on the other side of the sealed cavity.

[0009] As an alternative, the outer peripheries of the first ceramic sheet and the second ceramic sheet are brazed to a metal flange through a metallization layer, and the metallization layer together with the first ceramic sheet and the second ceramic sheet forms the sealed cavity.

[0010] As an alternative, at least one of the first ceramic sheet and the second ceramic sheet has grooves formed on its surface to increase the creepage distance.

[0011] As an alternative, the groove is filled with a dielectric material with high resistivity and high thermal conductivity.

[0012] As an optional solution, the first ceramic sheet and the second ceramic sheet have a purity of ≥99.5% and a density of ≥3.90 g / cm³. 3 High-purity, high-density alumina ceramics; Alternatively, the first ceramic sheet and the second ceramic sheet may be aluminum nitride ceramic or beryllium oxide ceramic.

[0013] As an alternative, the cooling medium is one of dry air, nitrogen, or sulfur hexafluoride gas; Alternatively, the cooling medium may be an insulating coolant.

[0014] As an optional feature, the through-wall assembly also includes sensors for monitoring the temperature or pressure within the sealed cavity.

[0015] As an optional solution, elastic sealing rings are provided between the conductor and the first ceramic sheet, as well as between the conductor and the second ceramic sheet.

[0016] The beneficial effects of this invention are: This invention provides a magnetic alloy loading cavity. During operation, the vacuum cavity inside the inner conductor assembly is in an ultra-high vacuum state, with a vacuum level reaching 1E-6 Pa. The first and second cavities outside the inner conductor assembly are filled with SF6 gas. Through conductors, the power source is fed to both ends of the ceramic ring. The magnetic alloy loading cavity provided by this invention, by maintaining an ultra-high vacuum in the vacuum cavity inside the inner conductor assembly and filling the first and second cavities outside the inner conductor assembly with SF6 insulating gas, forms a double composite insulation method. Under extremely high gradient conditions, it can maintain a compact overall structure, avoid the risk of gap breakdown, effectively suppress arcing, and significantly improve the withstand voltage and operational reliability of the magnetic alloy loading cavity, realizing a compact high gradient design for the magnetic alloy loading cavity. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the magnetic alloy loading cavity provided in an embodiment of the present invention; Figure 2 This is a cross-sectional view of the magnetic alloy loading cavity provided in an embodiment of the present invention; Figure 3 This is a cross-sectional view of the wall-penetrating component provided in an embodiment of the present invention.

[0018] In the picture: 10. Cavity shell; 11. First cavity; 12. Second cavity; 13. Third cavity; 20. Inner conductor assembly; 21. Vacuum pipe; 22. Ceramic ring; 23. Conductive ring; 24. Vacuum cavity; 30. Blind flange; 40. Through-wall assembly; 41. First ceramic plate; 42. Second ceramic plate; 43. Sealed cavity; 44. Medium inlet; 45. Medium outlet; 46. Metallization layer; 47. Metal flange; 48. Groove; 50. Conductor; 60. Magnetic alloy ring. Detailed Implementation

[0019] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar components or components having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0020] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium; or 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.

[0021] In the description of this invention, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0022] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0023] This embodiment provides a magnetic alloy loading cavity for use in a particle accelerator. Specifically, as... Figure 1 and Figure 2 As shown, the magnetic alloy loading cavity includes a cavity shell 10, an inner conductor assembly 20 coaxially disposed inside the cavity shell 10, and blind flanges 30 connecting the cavity shell 10 and the inner conductor assembly 20 at both axial ends. The inner conductor assembly 20 is tubular, and the interior of the inner conductor assembly 20 is a vacuum chamber 24. The vacuum chamber 24 is used to provide a motion environment for the particles and accelerate the particles according to the accelerating voltage.

[0024] like Figure 2 As shown, two annular third cavities 13 are formed within the outer shell 10, spaced apart along the axial direction. Each third cavity 13 contains multiple magnetic alloy rings 60, and the inner conductor assembly 20 coaxially passes through the multiple magnetic alloy rings 60. The magnetic alloy-loaded cavity is a type of large-scale high-power radio frequency device. It is a coaxial resonant cavity using magnetic alloy material as the inductor loading material. Due to the high permeability, high saturation magnetic flux density, high Curie temperature, and low Q value of magnetic alloy material, compared to traditional inductor-loaded high-frequency cavities, the cavity length can be shorter, the acceleration gradient can be higher, and the operating frequency band is wider. The cavity does not require tuning; that is, there is no need to wind bias windings on the magnetic alloy rings 60 or apply a DC magnetic field to change its permeability. This eliminates the need for a complex tuning control system, greatly simplifying the complex tuning control loop and making the cavity operation more stable. Therefore, it is often used in the field of high-power particle accelerators to meet the physical requirements of high beam current, short pulse width, and high stability.

[0025] Furthermore, such as Figure 2As shown, two first cavities 11 are formed between the inner conductor assembly 20 and the cavity shell 10, and a second cavity 12 is connected between the two first cavities 11. The first cavity 11 is located radially inside the third cavity 13, and the second cavity 12 is located between the two third cavities 13. The blind flanges 30 at both ends are sealed to the cavity shell 10 and the inner conductor assembly 20, so that the vacuum cavity 24 inside the inner conductor assembly 20 and the first cavity 11 and the second cavity 12 outside the inner conductor assembly 20 are both sealed spaces. The first cavity 11 and the second cavity 12 are both filled with insulating gas, which can be SF6 gas, as SF6 gas has better insulation properties.

[0026] like Figure 2 As shown, the inner conductor assembly 20 includes a vacuum pipe 21, a ceramic ring 22, and a conductive ring 23. Both ends of the ceramic ring 22 are connected to the conductive ring 23. The vacuum pipe 21 is connected to both ends of the ceramic ring 22 via the conductive ring 23. Both the ceramic ring 22 and the conductive ring 23 are located within the second cavity 12. The vacuum pipe 21 can be a stainless steel pipe, and the conductive ring 23 can be a copper ring. The magnetic alloy loading cavity also includes a through-wall assembly 40 and a conductor 50. The through-wall assembly 40 is connected to the periphery of the cavity shell 10 to seal the second cavity 12. The conductor 50 insulates through the through-wall assembly 40 and the second cavity 12 sequentially before connecting to the conductive ring 23. One end of the conductor 50 located outside the through-wall assembly 40 is connected to a power source. The conductor 50 can be a copper busbar. During operation, the vacuum chamber 24 inside the inner conductor assembly 20 is in an ultra-high vacuum state, with a vacuum degree of 1E-6Pa. The first cavity 11 and the second cavity 12 outside the inner conductor assembly 20 are filled with SF6 gas, which feeds the power source to both ends of the ceramic ring 22 through the conductor 50.

[0027] The magnetic alloy loading cavity provided in this embodiment maintains an ultra-high vacuum in the vacuum cavity 24 inside the inner conductor assembly 20, and fills the first cavity 11 and the second cavity 12 outside the inner conductor assembly 20 with SF6 insulating gas, forming a double composite insulation method. Under extremely high gradient conditions, it can maintain the overall compact structure, avoid the risk of gap breakdown, effectively suppress arcing, and significantly improve the withstand voltage and operational reliability of the magnetic alloy loading cavity, realizing a compact high gradient design for the magnetic alloy loading cavity.

[0028] In this embodiment, as Figure 1As shown, the number of through-wall components 40 and conductors 50 is set to two, and they are matched one-to-one. The two conductors 50 are arranged at intervals along the circular direction of the cavity shell 10 and are respectively connected to different conductive rings 23. The two conductors 50 represent positive and negative output electrodes, and are respectively connected to different conductive rings 23, so that the space between the two conductive rings 23 in the vacuum cavity 24 is an acceleration gap. When a particle beam is injected into the vacuum cavity 24, the charged particles are accelerated through this acceleration gap and then extracted from the vacuum cavity 24.

[0029] In the prior art, in order to achieve a high gradient, the system adopts a push-pull working mode, that is, two power sources feed power to both ends of the ceramic ring 22 respectively, and the output electrodes of the two power sources are introduced on the same straight line (for example, both at 0 degrees or 180 degrees). In the compact cavity space, the two output electrodes are too close to each other, which makes it very easy for arcing to occur between the electrodes.

[0030] To solve the above problems, such as Figure 1 As shown, in this embodiment, the central angle between the two conductors 50 is 90 degrees. For the push-pull operating mode, the two output electrodes are spatially offset by 90 degrees, which significantly increases the physical creepage distance between the two high-voltage electrodes and solves the problem of inter-electrode arcing in a compact space.

[0031] It should be noted that in this embodiment, the through-wall component 40, as a key interface component, undertakes two core functions: first, to achieve reliable sealing and isolation between the second cavity 12 and the external atmospheric environment; and second, to maintain the long-term insulation reliability of the conductor 50 where it passes through the cavity wall under high-frequency and high-voltage operating conditions.

[0032] In existing technologies, common through-wall components 40 are mostly designed based on power frequency (50Hz / 60Hz) conditions, and their material selection, structural form, and withstand voltage assessment are mainly suitable for low-frequency, high-voltage applications. However, when the operating frequency is increased to above MHz, the ceramic material of the traditional through-wall component 40 will generate significant dielectric loss under high-frequency alternating electric fields, causing local temperature rise, resulting in a decrease in the material's insulation performance, a significant reduction in withstand voltage, and a tendency to thermal breakdown. This makes it difficult to meet the stringent requirements of accelerator high-frequency loading cavities for insulation reliability, long-term stability, and power tolerance.

[0033] Therefore, such as Figure 3As shown, optionally, in this embodiment, the through-wall assembly 40 includes a first ceramic plate 41 and a second ceramic plate 42 coaxially arranged. The conductor 50 passes through the first ceramic plate 41 and the second ceramic plate 42 in sequence, forming a sealed cavity 43 between the first ceramic plate 41 and the second ceramic plate 42. The sealed cavity 43 is filled with a cooling medium. A medium inlet 44 is provided on one side of the sealed cavity 43, and a medium outlet 45 is provided on the other side of the sealed cavity 43. Specifically, the outer peripheries of the first ceramic plate 41 and the second ceramic plate 42 are brazed and sealed to a metal flange 47 through a metallization layer 46. The metal flange 47 can be selected as two flanges arranged at intervals, one above the other. The lower metal flange 47 can be connected to the outer shell 10 of the cavity. The medium inlet 44 and the medium outlet 45 are respectively provided on the metallization layer 46. The metallization layer 46, the first ceramic plate 41, and the second ceramic plate 42 together enclose the aforementioned sealed cavity 43.

[0034] Both the medium inlet 44 and the medium outlet 45 are connected to the cooling system, forming a closed-loop or unidirectional cooling channel. During operation, the cooling medium is forcibly pumped into the sealed cavity 43 through the medium inlet 44. As it flows through the inner surfaces of the first ceramic plate 41 and the second ceramic plate 42, it directly and efficiently removes the heat generated by the high-frequency dielectric loss of the ceramic plates, directly and specifically solving the problem of high-frequency loss heat generation, ensuring that the temperature rise of the through-wall assembly 40 is controllable when operating at full power. In the prior art, single-layer solid ceramic plates are mostly used, and heat dissipation relies solely on natural convection or conduction on the surface of the ceramic plates, which is inefficient and uneven. However, this application uses coaxially arranged double-layer ceramic plates, which are sealed with an outer periphery to form an annular sealed cavity 43. An external forced cooling system is connected to this sealed cavity 43 for convective heat dissipation, realizing the direct, efficient, and uniform removal of heat loss inside the through-wall assembly 40, solving the problem of thermal stress cracking caused by uneven heat dissipation at high frequencies, and realizing active control of the operating temperature.

[0035] Specifically, by adopting the aforementioned through-wall component 40, three major effects can be achieved: First, uniform heat dissipation. Since the cooling medium in the sealed cavity 43 has a large contact area with both ceramic plates (heating elements), heat is dissipated synchronously and uniformly, fundamentally avoiding the huge radial temperature difference and thermal stress caused by uneven heat dissipation on the inner and outer surfaces of traditional solid or single-layer ceramic plates. Second, thermal stress elimination. The uniform temperature field ensures uniform thermal expansion of the ceramic plates, effectively preventing ceramic cracking or brazing seal failure caused by thermal stress concentration, greatly improving the mechanical reliability and lifespan of the through-wall component 40. Finally, active temperature control capability. By adjusting the flow rate and velocity of the cooling system, the operating temperature of the through-wall component 40 can be actively controlled, ensuring that it always operates within the optimal temperature range and maintains stable performance.

[0036] In one optional embodiment, the cooling system may be a forced air cooling system, and the cooling medium is not limited to dry air. It may also be nitrogen (N2), sulfur hexafluoride (SF6) or other fluorinated inert gases with better insulation properties to further enhance the insulation of the sealed cavity 43 itself. No specific limitation is made here.

[0037] In another alternative embodiment, the cooling system may also be a forced liquid cooling system, and the cooling medium may be an insulating coolant, such as a fluorinated liquid. The forced liquid cooling system may include a micro-circulation pump and a radiator, which has higher heat dissipation efficiency, but the system is more complex.

[0038] In another alternative embodiment, the sealed cavity 43 may not be completely sealed. It may be designed to allow a small amount of cooling gas to seep in or out, forming a slight positive pressure, which can both dissipate heat and prevent external contaminants from entering.

[0039] In this embodiment, the ceramic sheet is configured as two layers (first ceramic sheet 41 and second ceramic sheet 42). In other optional embodiments, the ceramic sheet can also be configured as two or more layers to form two or more series-connected sealed cooling cavities, which are suitable for through-wall components 40 with higher voltage levels and longer lengths, and realize graded management of voltage gradient and heat.

[0040] In the existing technology, the wall-penetrating components 40 designed based on power frequency conditions have no special requirements for the purity, density and high-frequency loss characteristics of ceramics, and often use low-cost, general-performance industrial ceramics.

[0041] In this embodiment, the first ceramic sheet 41 and the second ceramic sheet 42 can be made of materials with a purity ≥99.5% and a density ≥3.90 g / cm³. 3 The high purity and high density of alumina ceramics ensure that there are very few impurity ions at the grain boundaries, thereby directly reducing ion polarization loss and conductivity loss under high frequency electric fields. The high density significantly reduces the micropores inside the ceramic sheet, eliminates the hidden danger of internal partial discharge, and directly improves the breakdown voltage threshold of the ceramic sheet, laying the foundation for high voltage and high frequency operation.

[0042] In other alternative embodiments, in addition to the high-purity alumina ceramics described above, the first ceramic sheet 41 and the second ceramic sheet 42 may also be made of aluminum nitride ceramics or beryllium oxide ceramics. Aluminum nitride ceramics are also an option due to their higher thermal conductivity, and are particularly suitable for applications with extremely high thermal management requirements. Although beryllium oxide ceramics have extremely high thermal conductivity, they require special treatment due to their toxicity. Other options, such as lead zirconate titanate-based composite ceramics, can also achieve low losses at specific frequencies through formulation adjustments.

[0043] In summary, in this embodiment, by selecting high-purity, high-density alumina ceramic as the insulating body, its dielectric loss at high frequencies is reduced, and the breakdown voltage of the ceramic sheet is increased. By adopting a double-ceramic-sheet composite structure, a sealed cavity 43 is formed between the two ceramic sheets, and a cooling system is introduced to force convection heat dissipation of the sealed cavity 43, ensuring uniform temperature distribution of the ceramic sheets and avoiding thermal stress cracking due to local overheating. This significantly reduces the dielectric loss and temperature rise of the through-wall assembly 40 under high-frequency operating conditions. Therefore, through the coordinated optimization of the ceramic material selection and structural design of the through-wall assembly 40, low loss, high withstand voltage, uniform heat dissipation, and reliable sealing of the through-wall assembly 40 under high voltage and high frequency conditions are achieved. It is especially suitable for special occasions in particle accelerators where the magnetic alloy loading cavity requires high frequency, high voltage, and high reliability.

[0044] In existing technologies, the surfaces of ceramic sheets are mostly smooth planes or simple umbrella-shaped structures, without sophisticated design to address the concentration of surface electric fields under high frequency and high voltage. In this embodiment, however, at least one of the first ceramic sheet 41 and the second ceramic sheet 42 has a groove 48 formed on its surface to increase the creepage distance. By designing a specific type of groove 48 on the surface of the ceramic sheet, the actual creepage distance on the ceramic sheet surface is increased. When there is a risk of surface discharge, the discharge development path is repeatedly "torsionalized" and "stretched" by the groove 48, extending the surface flashover path and significantly improving the surface flashover voltage of the ceramic sheet. This feature specifically addresses the surface discharge problem caused by the concentration of edge electric fields in the conductor 50 under high voltage and high frequency, and is key to improving the insulation capability of the through-wall assembly 40.

[0045] In addition, it should be noted that by combining high-purity dense ceramic material and the groove 48 on the surface of the ceramic sheet, the breakdown voltage and surface flashover voltage of the through-wall component 40 are significantly improved, which multiplies its insulation safety margin under MHz high frequency and tens of kilovolt high voltage, fundamentally reducing the risk of thermal breakdown and electrical breakdown, and enhancing the insulation stability and reliability of the through-wall component 40 under harsh electric field conditions.

[0046] In this embodiment, grooves 48 are formed on both sides of the first ceramic sheet 41 and the second ceramic sheet 42. Optionally, the grooves 48 can be concentric annular grooves, spiral grooves, or a series of radially distributed array grooves. The grooves 48 are not limited to mechanical engraving; they can also be made by laser ablation, abrasion, or molding. The shape of the grooves 48 can be optimized using electric field simulation software to form a personalized array of grooves with non-uniformity, varying depth, or curvature, in order to achieve optimal field strength homogenization.

[0047] Optionally, the groove 48 may be filled with a dielectric material with high resistivity and high thermal conductivity. Specifically, the groove 48 may be filled or coated with silicone grease or epoxy composite material with high resistivity and high thermal conductivity to further improve electric field uniformity and heat dissipation.

[0048] Optionally, the through-wall assembly 40 also includes a sensor for monitoring the temperature or pressure within the sealed cavity 43. The sensor enables active control of the operating temperature or pressure within the sealed cavity 43, ensuring it always operates within the optimal temperature or pressure range and maintains stable performance.

[0049] Optionally, elastic sealing rings are provided between the conductor 50 and the first ceramic plate 41, and between the conductor 50 and the second ceramic plate 42. The elastic sealing rings can provide auxiliary sealing and stress buffering. Optionally, the elastic sealing rings can be made of fluororubber O-rings resistant to high and low temperatures.

[0050] Alternatively, in addition to the aforementioned elastic sealing ring, a fully rigid seal can be achieved by glass sealing or secondary brazing on the entire outer side of the through-wall assembly 40, which is suitable for environments with extremely strict requirements for gas purity or vacuum environments.

[0051] Optionally, an equalizing ring may be installed at the end of conductor 50 to further improve the electric field distribution and suppress corona discharge.

[0052] In summary, the above-described through-wall component 40 is suitable for high-frequency environments above MHz and high-voltage environments of tens of kilovolts, and has low loss, high pressure resistance, excellent heat dissipation characteristics and reliable sealing performance, breaking through the technical bottleneck of the performance and reliability of the magnetic alloy loading cavity and even the entire accelerator system.

[0053] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A magnetic alloy loading cavity, characterized in that, The device includes a cavity shell (10), an inner conductor assembly (20) coaxially disposed inside the cavity shell (10), and blind flanges (30) connecting the cavity shell (10) and the inner conductor assembly (20) at both axial ends. The interior of the inner conductor assembly (20) is a vacuum chamber (24). Two first cavities (11) are formed between the inner conductor assembly (20) and the cavity shell (10), and a second cavity (12) is connected between the two first cavities (11). Both the first cavity (11) and the second cavity (12) are filled with insulating gas. The inner conductor assembly (20) includes a vacuum tube (21), a ceramic ring (22) and a conductive ring (23). The conductive ring (23) is connected to both ends of the ceramic ring (22). The vacuum tube (21) is connected to both ends of the ceramic ring (22) through the conductive ring (23). The magnetic alloy loading cavity also includes a wall-penetrating assembly (40) and a conductor (50). The wall-penetrating assembly (40) is connected to the periphery of the cavity shell (10) to seal the second cavity (12). The conductor (50) passes through the wall-penetrating assembly (40) and the second cavity (12) in sequence and is then connected to the conductive ring (23).

2. The magnetic alloy loading cavity according to claim 1, characterized in that, The number of the through-wall assembly (40) and the conductor (50) are both set to two and they are matched one-to-one. The two conductors (50) are arranged at intervals along the circular direction of the cavity shell (10) and are respectively connected to different conductive rings (23). The central angle between the two conductors (50) is 90 degrees.

3. The magnetic alloy loading cavity according to claim 1, characterized in that, The through-wall assembly (40) includes a first ceramic plate (41) and a second ceramic plate (42) arranged coaxially. The conductor (50) passes through the first ceramic plate (41) and the second ceramic plate (42) in sequence. A sealed cavity (43) is formed between the first ceramic plate (41) and the second ceramic plate (42). The sealed cavity (43) is filled with a cooling medium. A medium inlet (44) is provided on one side of the sealed cavity (43), and a medium outlet (45) is provided on the other side of the sealed cavity (43).

4. The magnetic alloy loading cavity according to claim 3, characterized in that, The outer periphery of the first ceramic piece (41) and the second ceramic piece (42) are brazed to the metal flange (47) through a metallization layer (46), and the metallization layer (46) together with the first ceramic piece (41) and the second ceramic piece (42) form the sealed cavity (43).

5. The magnetic alloy loading cavity according to claim 3, characterized in that, At least one of the first ceramic sheet (41) and the second ceramic sheet (42) has a groove (48) formed on its surface to increase the creepage distance.

6. The magnetic alloy loading cavity according to claim 5, characterized in that, The groove (48) is filled with a dielectric material with high resistivity and high thermal conductivity.

7. The magnetic alloy loading cavity according to claim 3, characterized in that, The first ceramic sheet (41) and the second ceramic sheet (42) have a purity ≥ 99.5% and a density ≥ 3.90 g / cm³. 3 High-purity, high-density alumina ceramics; Alternatively, the first ceramic sheet (41) and the second ceramic sheet (42) may be aluminum nitride ceramic or beryllium oxide ceramic.

8. The magnetic alloy loading cavity according to claim 3, characterized in that, The cooling medium is one of dry air, nitrogen, or sulfur hexafluoride gas; Alternatively, the cooling medium may be an insulating coolant.

9. The magnetic alloy loading cavity according to claim 3, characterized in that, The through-wall assembly (40) also includes sensors for monitoring the temperature or pressure within the sealed cavity (43).

10. The magnetic alloy loading cavity according to claim 3, characterized in that, An elastic sealing ring is provided between the conductor (50) and the first ceramic sheet (41) and between the conductor (50) and the second ceramic sheet (42).

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